]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/net/necp_client.c
xnu-6153.121.1.tar.gz
[apple/xnu.git] / bsd / net / necp_client.c
index 83666005b0843f3088f60ab9b832f37e0cb0ae66..0b3ef6782936a213c787e89565fea1a25a2aeaa0 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2017 Apple Inc. All rights reserved.
+ * Copyright (c) 2015-2019 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
@@ -41,6 +41,7 @@
 #include <net/ntstat.h>
 
 #include <netinet/in_pcb.h>
+#include <netinet/in_var.h>
 #include <netinet/ip.h>
 #include <netinet/ip6.h>
 #include <netinet/mp_pcb.h>
@@ -66,6 +67,8 @@
 #include <sys/codesign.h>
 #include <libkern/section_keywords.h>
 
+#include <os/refcnt.h>
+
 
 /*
  * NECP Client Architecture
 
 extern u_int32_t necp_debug;
 
-// proc_best_name() is declared here in advance of it landing in a header file.
-// See comment in kern_proc.c
-extern char *proc_best_name(proc_t p);
-
-static int noop_read(struct fileproc *, struct uio *, int, vfs_context_t);
-static int noop_write(struct fileproc *, struct uio *, int, vfs_context_t);
-static int noop_ioctl(struct fileproc *, unsigned long, caddr_t,
-               vfs_context_t);
 static int necpop_select(struct fileproc *, int, void *, vfs_context_t);
 static int necpop_close(struct fileglob *, vfs_context_t);
-static int necpop_kqfilter(struct fileproc *, struct knote *,
-               struct kevent_internal_s *kev, vfs_context_t);
+static int necpop_kqfilter(struct fileproc *, struct knote *, struct kevent_qos_s *);
 
 // Timer functions
 static int necp_timeout_microseconds = 1000 * 100; // 100ms
@@ -169,6 +163,8 @@ static int necp_socket_flow_count = 0;
 static int necp_if_flow_count = 0;
 static int necp_observer_message_limit = 256;
 
+os_refgrp_decl(static, necp_client_refgrp, "NECPClientRefGroup", NULL);
+
 SYSCTL_INT(_net_necp, NECPCTL_CLIENT_FD_COUNT, client_fd_count, CTLFLAG_LOCKED | CTLFLAG_RD, &necp_client_fd_count, 0, "");
 SYSCTL_INT(_net_necp, NECPCTL_OBSERVER_FD_COUNT, observer_fd_count, CTLFLAG_LOCKED | CTLFLAG_RD, &necp_observer_fd_count, 0, "");
 SYSCTL_INT(_net_necp, NECPCTL_CLIENT_COUNT, client_count, CTLFLAG_LOCKED | CTLFLAG_RD, &necp_client_count, 0, "");
@@ -176,48 +172,63 @@ SYSCTL_INT(_net_necp, NECPCTL_SOCKET_FLOW_COUNT, socket_flow_count, CTLFLAG_LOCK
 SYSCTL_INT(_net_necp, NECPCTL_IF_FLOW_COUNT, if_flow_count, CTLFLAG_LOCKED | CTLFLAG_RD, &necp_if_flow_count, 0, "");
 SYSCTL_INT(_net_necp, NECPCTL_OBSERVER_MESSAGE_LIMIT, observer_message_limit, CTLFLAG_LOCKED | CTLFLAG_RW, &necp_observer_message_limit, 256, "");
 
-#define NECP_MAX_CLIENT_LIST_SIZE              1024 * 1024 // 1MB
+#define NECP_MAX_CLIENT_LIST_SIZE               1024 * 1024 // 1MB
+#define NECP_MAX_AGENT_ACTION_SIZE              256
 
 extern int tvtohz(struct timeval *);
 extern unsigned int get_maxmtu(struct rtentry *);
 
 // Parsed parameters
-#define NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR                                0x00001
-#define NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR                       0x00002
-#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF                       0x00004
-#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF                     0x00008
-#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE           0x00010
-#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE         0x00020
-#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT                    0x00040
-#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT          0x00080
-#define NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT           0x00100
-#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE       0x00200
-#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE     0x00400
-#define NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE      0x00800
-#define NECP_PARSED_PARAMETERS_FIELD_FLAGS                                     0x01000
-#define NECP_PARSED_PARAMETERS_FIELD_IP_PROTOCOL                       0x02000
-#define NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_PID                     0x04000
-#define NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_UUID                    0x08000
-#define NECP_PARSED_PARAMETERS_FIELD_TRAFFIC_CLASS                     0x10000
-#define NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT                                0x20000
-
-#define NECP_MAX_PARSED_PARAMETERS 16
+#define NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR                         0x00001
+#define NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR                        0x00002
+#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF                        0x00004
+#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF                      0x00008
+#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE            0x00010
+#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE          0x00020
+#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT                     0x00040
+#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT           0x00080
+#define NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT            0x00100
+#define NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT                      0x00200
+#define NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE        0x00400
+#define NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE      0x00800
+#define NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE       0x01000
+#define NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT_TYPE         0x02000
+#define NECP_PARSED_PARAMETERS_FIELD_FLAGS                                      0x04000
+#define NECP_PARSED_PARAMETERS_FIELD_IP_PROTOCOL                        0x08000
+#define NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_PID                      0x10000
+#define NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_UUID                     0x20000
+#define NECP_PARSED_PARAMETERS_FIELD_TRAFFIC_CLASS                      0x40000
+#define NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT                         0x80000
+#define NECP_PARSED_PARAMETERS_FIELD_DELEGATED_UPID                                             0x100000
+#define NECP_PARSED_PARAMETERS_FIELD_ETHERTYPE                                             0x200000
+#define NECP_PARSED_PARAMETERS_FIELD_TRANSPORT_PROTOCOL                        0x400000
+#define NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR_PREFERENCE                                              0x800000
+
+
+#define NECP_MAX_INTERFACE_PARAMETERS 16
+#define NECP_MAX_AGENT_PARAMETERS 4
 struct necp_client_parsed_parameters {
        u_int32_t valid_fields;
        u_int32_t flags;
+       u_int64_t delegated_upid;
        union necp_sockaddr_union local_addr;
        union necp_sockaddr_union remote_addr;
        u_int32_t required_interface_index;
-       char prohibited_interfaces[IFXNAMSIZ][NECP_MAX_PARSED_PARAMETERS];
+       char prohibited_interfaces[NECP_MAX_INTERFACE_PARAMETERS][IFXNAMSIZ];
        u_int8_t required_interface_type;
-       u_int8_t prohibited_interface_types[NECP_MAX_PARSED_PARAMETERS];
-       struct necp_client_parameter_netagent_type required_netagent_types[NECP_MAX_PARSED_PARAMETERS];
-       struct necp_client_parameter_netagent_type prohibited_netagent_types[NECP_MAX_PARSED_PARAMETERS];
-       struct necp_client_parameter_netagent_type preferred_netagent_types[NECP_MAX_PARSED_PARAMETERS];
-       uuid_t required_netagents[NECP_MAX_PARSED_PARAMETERS];
-       uuid_t prohibited_netagents[NECP_MAX_PARSED_PARAMETERS];
-       uuid_t preferred_netagents[NECP_MAX_PARSED_PARAMETERS];
-       u_int16_t ip_protocol;
+       u_int8_t local_address_preference;
+       u_int8_t prohibited_interface_types[NECP_MAX_INTERFACE_PARAMETERS];
+       struct necp_client_parameter_netagent_type required_netagent_types[NECP_MAX_AGENT_PARAMETERS];
+       struct necp_client_parameter_netagent_type prohibited_netagent_types[NECP_MAX_AGENT_PARAMETERS];
+       struct necp_client_parameter_netagent_type preferred_netagent_types[NECP_MAX_AGENT_PARAMETERS];
+       struct necp_client_parameter_netagent_type avoided_netagent_types[NECP_MAX_AGENT_PARAMETERS];
+       uuid_t required_netagents[NECP_MAX_AGENT_PARAMETERS];
+       uuid_t prohibited_netagents[NECP_MAX_AGENT_PARAMETERS];
+       uuid_t preferred_netagents[NECP_MAX_AGENT_PARAMETERS];
+       uuid_t avoided_netagents[NECP_MAX_AGENT_PARAMETERS];
+       u_int8_t ip_protocol;
+       u_int8_t transport_protocol;
+       u_int16_t ethertype;
        pid_t effective_pid;
        uuid_t effective_uuid;
        u_int32_t traffic_class;
@@ -225,25 +236,28 @@ struct necp_client_parsed_parameters {
 
 static bool
 necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_parameters,
-                                                                  u_int *return_ifindex);
+    u_int *return_ifindex, bool *validate_agents);
 
 static bool
 necp_ifnet_matches_local_address(struct ifnet *ifp, struct sockaddr *sa);
 
 static bool
 necp_ifnet_matches_parameters(struct ifnet *ifp,
-                                                         struct necp_client_parsed_parameters *parsed_parameters,
-                                                         u_int32_t *preferred_count, bool ignore_require_if);
+    struct necp_client_parsed_parameters *parsed_parameters,
+    u_int32_t override_flags,
+    u_int32_t *preferred_count,
+    bool secondary_interface,
+    bool require_scoped_field);
 
 static const struct fileops necp_fd_ops = {
-       .fo_type = DTYPE_NETPOLICY,
-       .fo_read = noop_read,
-       .fo_write = noop_write,
-       .fo_ioctl = noop_ioctl,
-       .fo_select = necpop_select,
-       .fo_close = necpop_close,
+       .fo_type     = DTYPE_NETPOLICY,
+       .fo_read     = fo_no_read,
+       .fo_write    = fo_no_write,
+       .fo_ioctl    = fo_no_ioctl,
+       .fo_select   = necpop_select,
+       .fo_close    = necpop_close,
+       .fo_drain    = fo_no_drain,
        .fo_kqfilter = necpop_kqfilter,
-       .fo_drain = NULL,
 };
 
 struct necp_client_assertion {
@@ -253,6 +267,8 @@ struct necp_client_assertion {
 
 struct necp_client_flow_header {
        struct necp_tlv_header outer_header;
+       struct necp_tlv_header flow_id_tlv_header;
+       uuid_t flow_id;
        struct necp_tlv_header flags_tlv_header;
        u_int32_t flags_value;
        struct necp_tlv_header interface_tlv_header;
@@ -272,23 +288,75 @@ struct necp_client_nexus_flow_header {
        u_int8_t tfo_cookie_value[NECP_TFO_COOKIE_LEN_MAX];
 } __attribute__((__packed__));
 
+
+struct necp_client_flow {
+       LIST_ENTRY(necp_client_flow) flow_chain;
+       unsigned invalid : 1;
+       unsigned nexus : 1; // If true, flow is a nexus; if false, flow is attached to socket
+       unsigned socket : 1;
+       unsigned viable : 1;
+       unsigned assigned : 1;
+       unsigned has_protoctl_event : 1;
+       unsigned check_tcp_heuristics : 1;
+       unsigned _reserved : 1;
+       union {
+               uuid_t nexus_agent;
+               struct {
+                       void *socket_handle;
+                       necp_client_flow_cb cb;
+               };
+       } u;
+       uint32_t interface_index;
+       uint16_t interface_flags;
+       uint32_t necp_flow_flags;
+       struct necp_client_flow_protoctl_event protoctl_event;
+       union necp_sockaddr_union local_addr;
+       union necp_sockaddr_union remote_addr;
+
+       size_t assigned_results_length;
+       u_int8_t *assigned_results;
+};
+
+struct necp_client_flow_registration {
+       RB_ENTRY(necp_client_flow_registration) fd_link;
+       RB_ENTRY(necp_client_flow_registration) global_link;
+       RB_ENTRY(necp_client_flow_registration) client_link;
+       LIST_ENTRY(necp_client_flow_registration) collect_stats_chain;
+       uuid_t registration_id;
+       u_int32_t flags;
+       unsigned flow_result_read : 1;
+       unsigned defunct : 1;
+       void *interface_handle;
+       necp_client_flow_cb interface_cb;
+       struct necp_client *client;
+       LIST_HEAD(_necp_registration_flow_list, necp_client_flow) flow_list;
+       u_int64_t last_interface_details __attribute__((aligned(sizeof(u_int64_t))));
+};
+
+static int necp_client_flow_id_cmp(struct necp_client_flow_registration *flow0, struct necp_client_flow_registration *flow1);
+
+RB_HEAD(_necp_client_flow_tree, necp_client_flow_registration);
+RB_PROTOTYPE_PREV(_necp_client_flow_tree, necp_client_flow_registration, client_link, necp_client_flow_id_cmp);
+RB_GENERATE_PREV(_necp_client_flow_tree, necp_client_flow_registration, client_link, necp_client_flow_id_cmp);
+
+#define NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT 4
+#define NECP_CLIENT_MAX_INTERFACE_OPTIONS 16
+
+#define NECP_CLIENT_INTERFACE_OPTION_EXTRA_COUNT (NECP_CLIENT_MAX_INTERFACE_OPTIONS - NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT)
+
 struct necp_client {
        RB_ENTRY(necp_client) link;
        RB_ENTRY(necp_client) global_link;
-       LIST_ENTRY(necp_client) collect_stats_chain;
 
        decl_lck_mtx_data(, lock);
        decl_lck_mtx_data(, route_lock);
-       uint32_t reference_count;
+       os_refcnt_t reference_count;
 
        uuid_t client_id;
        unsigned result_read : 1;
-       unsigned flow_result_read : 1;
        unsigned allow_multiple_flows : 1;
+       unsigned legacy_client_is_flow : 1;
 
-       unsigned defunct : 1;
-       unsigned background : 1;
-       unsigned background_update : 1;
        unsigned platform_binary : 1;
 
        size_t result_length;
@@ -296,16 +364,26 @@ struct necp_client {
 
        necp_policy_id policy_id;
 
-       u_int16_t ip_protocol;
+       u_int8_t ip_protocol;
        int proc_pid;
 
-       LIST_HEAD(_necp_client_flow_list, necp_client_flow) flow_list;
+       u_int64_t delegated_upid;
+
+       struct _necp_client_flow_tree flow_registrations;
        LIST_HEAD(_necp_client_assertion_list, necp_client_assertion) assertion_list;
 
        struct rtentry *current_route;
 
-       void *interface_handle;
-       void (*interface_cb)(void *handle, int action, struct necp_client_flow *flow);
+       struct necp_client_interface_option interface_options[NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT];
+       struct necp_client_interface_option *extra_interface_options;
+       u_int8_t interface_option_count; // Number in interface_options + extra_interface_options
+
+       struct necp_client_result_netagent failed_trigger_agent;
+
+       void *agent_handle;
+
+       uuid_t override_euuid;
+
 
        size_t parameters_length;
        u_int8_t parameters[0];
@@ -320,8 +398,9 @@ struct necp_client {
 #define NECP_CLIENT_ROUTE_UNLOCK(_c) lck_mtx_unlock(&_c->route_lock)
 
 static void necp_client_retain_locked(struct necp_client *client);
-static void necp_client_retain(struct necp_client *client);
+
 static bool necp_client_release_locked(struct necp_client *client);
+static bool necp_client_release(struct necp_client *client);
 
 static void
 necp_client_add_assertion(struct necp_client *client, uuid_t netagent_uuid);
@@ -329,18 +408,22 @@ necp_client_add_assertion(struct necp_client *client, uuid_t netagent_uuid);
 static bool
 necp_client_remove_assertion(struct necp_client *client, uuid_t netagent_uuid);
 
-LIST_HEAD(_necp_client_list, necp_client);
-static struct _necp_client_list necp_collect_stats_client_list;
+LIST_HEAD(_necp_flow_registration_list, necp_client_flow_registration);
+static struct _necp_flow_registration_list necp_collect_stats_flow_list;
 
-struct necp_client_defunct {
-       LIST_ENTRY(necp_client_defunct) chain;
+struct necp_flow_defunct {
+       LIST_ENTRY(necp_flow_defunct) chain;
 
-       uuid_t client_id;
+       uuid_t flow_id;
        uuid_t nexus_agent;
+       void *agent_handle;
        int proc_pid;
+       u_int32_t flags;
+       struct necp_client_agent_parameters close_parameters;
+       bool has_close_parameters;
 };
 
-LIST_HEAD(_necp_client_defunct_list, necp_client_defunct);
+LIST_HEAD(_necp_flow_defunct_list, necp_flow_defunct);
 
 static int necp_client_id_cmp(struct necp_client *client0, struct necp_client *client1);
 
@@ -352,7 +435,16 @@ RB_HEAD(_necp_client_global_tree, necp_client);
 RB_PROTOTYPE_PREV(_necp_client_global_tree, necp_client, global_link, necp_client_id_cmp);
 RB_GENERATE_PREV(_necp_client_global_tree, necp_client, global_link, necp_client_id_cmp);
 
+RB_HEAD(_necp_fd_flow_tree, necp_client_flow_registration);
+RB_PROTOTYPE_PREV(_necp_fd_flow_tree, necp_client_flow_registration, fd_link, necp_client_flow_id_cmp);
+RB_GENERATE_PREV(_necp_fd_flow_tree, necp_client_flow_registration, fd_link, necp_client_flow_id_cmp);
+
+RB_HEAD(_necp_client_flow_global_tree, necp_client_flow_registration);
+RB_PROTOTYPE_PREV(_necp_client_flow_global_tree, necp_client_flow_registration, global_link, necp_client_flow_id_cmp);
+RB_GENERATE_PREV(_necp_client_flow_global_tree, necp_client_flow_registration, global_link, necp_client_flow_id_cmp);
+
 static struct _necp_client_global_tree necp_client_global_tree;
+static struct _necp_client_flow_global_tree necp_client_flow_global_tree;
 
 struct necp_client_update {
        TAILQ_ENTRY(necp_client_update) chain;
@@ -363,13 +455,22 @@ struct necp_client_update {
        struct necp_client_observer_update update;
 };
 
+
+#define NAIF_ATTACHED   0x1     // arena is attached to list
+#define NAIF_REDIRECT   0x2     // arena mmap has been redirected
+#define NAIF_DEFUNCT    0x4     // arena is now defunct
+
 struct necp_fd_data {
        u_int8_t necp_fd_type;
        LIST_ENTRY(necp_fd_data) chain;
        struct _necp_client_tree clients;
+       struct _necp_fd_flow_tree flows;
        TAILQ_HEAD(_necp_client_update_list, necp_client_update) update_list;
        int update_count;
        int flags;
+
+       unsigned background : 1;
+
        int proc_pid;
        decl_lck_mtx_data(, fd_lock);
        struct selinfo si;
@@ -383,25 +484,33 @@ struct necp_fd_data {
 static LIST_HEAD(_necp_fd_list, necp_fd_data) necp_fd_list;
 static LIST_HEAD(_necp_fd_observer_list, necp_fd_data) necp_fd_observer_list;
 
-#define        NECP_CLIENT_FD_ZONE_MAX                 128
-#define        NECP_CLIENT_FD_ZONE_NAME                "necp.clientfd"
+#define NECP_CLIENT_FD_ZONE_MAX                 128
+#define NECP_CLIENT_FD_ZONE_NAME                "necp.clientfd"
+
+static unsigned int necp_client_fd_size;        /* size of zone element */
+static struct zone *necp_client_fd_zone;        /* zone for necp_fd_data */
 
-static unsigned int necp_client_fd_size;       /* size of zone element */
-static struct zone *necp_client_fd_zone;       /* zone for necp_fd_data */
+#define NECP_FLOW_ZONE_NAME                                     "necp.flow"
+#define NECP_FLOW_REGISTRATION_ZONE_NAME        "necp.flowregistration"
 
-#define        NECP_FLOW_ZONE_MAX                      512
-#define        NECP_FLOW_ZONE_NAME                     "necp.flow"
+static unsigned int necp_flow_size;             /* size of necp_client_flow */
+static struct mcache *necp_flow_cache;  /* cache for necp_client_flow */
 
-static unsigned int necp_flow_size;                    /* size of zone element */
-static struct zone *necp_flow_zone;                    /* zone for necp_client_flow */
+static unsigned int necp_flow_registration_size;        /* size of necp_client_flow_registration */
+static struct mcache *necp_flow_registration_cache;     /* cache for necp_client_flow_registration */
 
-static lck_grp_attr_t  *necp_fd_grp_attr       = NULL;
-static lck_attr_t              *necp_fd_mtx_attr       = NULL;
-static lck_grp_t               *necp_fd_mtx_grp        = NULL;
+#define NECP_ARENA_INFO_ZONE_MAX                128
+#define NECP_ARENA_INFO_ZONE_NAME               "necp.arenainfo"
+
+
+static  lck_grp_attr_t  *necp_fd_grp_attr       = NULL;
+static  lck_attr_t              *necp_fd_mtx_attr       = NULL;
+static  lck_grp_t               *necp_fd_mtx_grp        = NULL;
 
 decl_lck_rw_data(static, necp_fd_lock);
 decl_lck_rw_data(static, necp_observer_lock);
 decl_lck_rw_data(static, necp_client_tree_lock);
+decl_lck_rw_data(static, necp_flow_tree_lock);
 decl_lck_rw_data(static, necp_collect_stats_list_lock);
 
 #define NECP_STATS_LIST_LOCK_EXCLUSIVE() lck_rw_lock_exclusive(&necp_collect_stats_list_lock)
@@ -411,6 +520,12 @@ decl_lck_rw_data(static, necp_collect_stats_list_lock);
 #define NECP_CLIENT_TREE_LOCK_EXCLUSIVE() lck_rw_lock_exclusive(&necp_client_tree_lock)
 #define NECP_CLIENT_TREE_LOCK_SHARED() lck_rw_lock_shared(&necp_client_tree_lock)
 #define NECP_CLIENT_TREE_UNLOCK() lck_rw_done(&necp_client_tree_lock)
+#define NECP_CLIENT_TREE_ASSERT_LOCKED() LCK_RW_ASSERT(&necp_client_tree_lock, LCK_RW_ASSERT_HELD)
+
+#define NECP_FLOW_TREE_LOCK_EXCLUSIVE() lck_rw_lock_exclusive(&necp_flow_tree_lock)
+#define NECP_FLOW_TREE_LOCK_SHARED() lck_rw_lock_shared(&necp_flow_tree_lock)
+#define NECP_FLOW_TREE_UNLOCK() lck_rw_done(&necp_flow_tree_lock)
+#define NECP_FLOW_TREE_ASSERT_LOCKED() LCK_RW_ASSERT(&necp_flow_tree_lock, LCK_RW_ASSERT_HELD)
 
 #define NECP_FD_LIST_LOCK_EXCLUSIVE() lck_rw_lock_exclusive(&necp_fd_lock)
 #define NECP_FD_LIST_LOCK_SHARED() lck_rw_lock_shared(&necp_fd_lock)
@@ -424,7 +539,8 @@ decl_lck_rw_data(static, necp_collect_stats_list_lock);
 
 // Take NECP_FD_LIST_LOCK when accessing or modifying the necp_fd_list
 // Take NECP_CLIENT_TREE_LOCK when accessing or modifying the necp_client_global_tree
-// Take NECP_STATS_LIST_LOCK when accessing or modifying the necp_collect_stats_client_list
+// Take NECP_FLOW_TREE_LOCK when accessing or modifying the necp_client_flow_global_tree
+// Take NECP_STATS_LIST_LOCK when accessing or modifying the necp_collect_stats_flow_list
 // Take NECP_FD_LOCK when accessing or modifying an necp_fd_data entry
 // Take NECP_CLIENT_LOCK when accessing or modifying a single necp_client
 // Take NECP_CLIENT_ROUTE_LOCK when accessing or modifying a client's route
@@ -434,37 +550,15 @@ decl_lck_rw_data(static, necp_collect_stats_list_lock);
 // 2. NECP_FD_LOCK (any)
 // 3. NECP_CLIENT_TREE_LOCK
 // 4. NECP_CLIENT_LOCK (any)
-// 5. NECP_STATS_LIST_LOCK
-// 6. NECP_CLIENT_ROUTE_LOCK (any)
+// 5. NECP_FLOW_TREE_LOCK
+// 6. NECP_STATS_LIST_LOCK
+// 7. NECP_CLIENT_ROUTE_LOCK (any)
 
 static thread_call_t necp_client_update_tcall;
 
 
 /// NECP file descriptor functions
 
-static int
-noop_read(struct fileproc *fp, struct uio *uio, int flags, vfs_context_t ctx)
-{
-#pragma unused(fp, uio, flags, ctx)
-       return (ENXIO);
-}
-
-static int
-noop_write(struct fileproc *fp, struct uio *uio, int flags,
-                  vfs_context_t ctx)
-{
-#pragma unused(fp, uio, flags, ctx)
-       return (ENXIO);
-}
-
-static int
-noop_ioctl(struct fileproc *fp, unsigned long com, caddr_t data,
-                  vfs_context_t ctx)
-{
-#pragma unused(fp, com, data, ctx)
-       return (ENOTTY);
-}
-
 static void
 necp_fd_notify(struct necp_fd_data *fd_data, bool locked)
 {
@@ -485,6 +579,19 @@ necp_fd_notify(struct necp_fd_data *fd_data, bool locked)
        }
 }
 
+static inline bool
+necp_client_has_unread_flows(struct necp_client *client)
+{
+       NECP_CLIENT_ASSERT_LOCKED(client);
+       struct necp_client_flow_registration *flow_registration = NULL;
+       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+               if (!flow_registration->flow_result_read) {
+                       return true;
+               }
+       }
+       return false;
+}
+
 static int
 necp_fd_poll(struct necp_fd_data *fd_data, int events, void *wql, struct proc *p, int is_kevent)
 {
@@ -504,11 +611,11 @@ necp_fd_poll(struct necp_fd_data *fd_data, int events, void *wql, struct proc *p
                        bool has_unread_clients = FALSE;
                        RB_FOREACH(client, _necp_client_tree, &fd_data->clients) {
                                NECP_CLIENT_LOCK(client);
-                               if (!client->result_read || !client->flow_result_read) {
+                               if (!client->result_read || necp_client_has_unread_flows(client)) {
                                        has_unread_clients = TRUE;
                                }
                                NECP_CLIENT_UNLOCK(client);
-                               if (has_unread_clients)  {
+                               if (has_unread_clients) {
                                        break;
                                }
                        }
@@ -519,35 +626,123 @@ necp_fd_poll(struct necp_fd_data *fd_data, int events, void *wql, struct proc *p
                }
        }
 
-       return (revents);
+       return revents;
+}
+
+static inline void
+necp_generate_client_id(uuid_t client_id, bool is_flow)
+{
+       uuid_generate_random(client_id);
+
+       if (is_flow) {
+               client_id[9] |= 0x01;
+       } else {
+               client_id[9] &= ~0x01;
+       }
+}
+
+static inline bool
+necp_client_id_is_flow(uuid_t client_id)
+{
+       return client_id[9] & 0x01;
+}
+
+static struct necp_client *
+necp_find_client_and_lock(uuid_t client_id)
+{
+       NECP_CLIENT_TREE_ASSERT_LOCKED();
+
+       struct necp_client *client = NULL;
+
+       if (necp_client_id_is_flow(client_id)) {
+               NECP_FLOW_TREE_LOCK_SHARED();
+               struct necp_client_flow_registration find;
+               uuid_copy(find.registration_id, client_id);
+               struct necp_client_flow_registration *flow = RB_FIND(_necp_client_flow_global_tree, &necp_client_flow_global_tree, &find);
+               if (flow != NULL) {
+                       client = flow->client;
+               }
+               NECP_FLOW_TREE_UNLOCK();
+       } else {
+               struct necp_client find;
+               uuid_copy(find.client_id, client_id);
+               client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
+       }
+
+       if (client != NULL) {
+               NECP_CLIENT_LOCK(client);
+       }
+
+       return client;
+}
+
+static struct necp_client_flow_registration *
+necp_client_find_flow(struct necp_client *client, uuid_t flow_id)
+{
+       NECP_CLIENT_ASSERT_LOCKED(client);
+       struct necp_client_flow_registration *flow = NULL;
+
+       if (necp_client_id_is_flow(flow_id)) {
+               struct necp_client_flow_registration find;
+               uuid_copy(find.registration_id, flow_id);
+               flow = RB_FIND(_necp_client_flow_tree, &client->flow_registrations, &find);
+       } else {
+               flow = RB_ROOT(&client->flow_registrations);
+       }
+
+       return flow;
 }
 
 static struct necp_client *
-necp_client_fd_find_client_and_lock(struct necp_fd_data *client_fd, uuid_t client_id)
+necp_client_fd_find_client_unlocked(struct necp_fd_data *client_fd, uuid_t client_id)
 {
-       struct necp_client find;
        NECP_FD_ASSERT_LOCKED(client_fd);
-       uuid_copy(find.client_id, client_id);
-       struct necp_client *client = RB_FIND(_necp_client_tree, &client_fd->clients, &find);
+       struct necp_client *client = NULL;
+
+       if (necp_client_id_is_flow(client_id)) {
+               struct necp_client_flow_registration find;
+               uuid_copy(find.registration_id, client_id);
+               struct necp_client_flow_registration *flow = RB_FIND(_necp_fd_flow_tree, &client_fd->flows, &find);
+               if (flow != NULL) {
+                       client = flow->client;
+               }
+       } else {
+               struct necp_client find;
+               uuid_copy(find.client_id, client_id);
+               client = RB_FIND(_necp_client_tree, &client_fd->clients, &find);
+       }
+
+       return client;
+}
 
+static struct necp_client *
+necp_client_fd_find_client_and_lock(struct necp_fd_data *client_fd, uuid_t client_id)
+{
+       struct necp_client *client = necp_client_fd_find_client_unlocked(client_fd, client_id);
        if (client != NULL) {
                NECP_CLIENT_LOCK(client);
        }
 
-       return (client);
+       return client;
 }
 
 static inline int
 necp_client_id_cmp(struct necp_client *client0, struct necp_client *client1)
 {
-       return (uuid_compare(client0->client_id, client1->client_id));
+       return uuid_compare(client0->client_id, client1->client_id);
+}
+
+static inline int
+necp_client_flow_id_cmp(struct necp_client_flow_registration *flow0, struct necp_client_flow_registration *flow1)
+{
+       return uuid_compare(flow0->registration_id, flow1->registration_id);
 }
 
 static int
 necpop_select(struct fileproc *fp, int which, void *wql, vfs_context_t ctx)
 {
 #pragma unused(fp, which, wql, ctx)
-       return (0);
+       return 0;
        struct necp_fd_data *fd_data = NULL;
        int revents = 0;
        int events = 0;
@@ -555,27 +750,27 @@ necpop_select(struct fileproc *fp, int which, void *wql, vfs_context_t ctx)
 
        fd_data = (struct necp_fd_data *)fp->f_fglob->fg_data;
        if (fd_data == NULL) {
-               return (0);
+               return 0;
        }
 
        procp = vfs_context_proc(ctx);
 
        switch (which) {
-               case FREAD: {
-                       events = POLLIN;
-                       break;
-               }
+       case FREAD: {
+               events = POLLIN;
+               break;
+       }
 
-               default: {
-                       return (1);
-               }
+       default: {
+               return 1;
+       }
        }
 
        NECP_FD_LOCK(fd_data);
        revents = necp_fd_poll(fd_data, events, wql, procp, 0);
        NECP_FD_UNLOCK(fd_data);
 
-       return ((events & revents) ? 1 : 0);
+       return (events & revents) ? 1 : 0;
 }
 
 static void
@@ -597,9 +792,8 @@ necp_fd_knread(struct knote *kn, long hint)
 }
 
 static int
-necp_fd_knrprocess(struct knote *kn, struct filt_process_s *data, struct kevent_internal_s *kev)
+necp_fd_knrprocess(struct knote *kn, struct kevent_qos_s *kev)
 {
-#pragma unused(data)
        struct necp_fd_data *fd_data;
        int revents;
        int res;
@@ -610,14 +804,14 @@ necp_fd_knrprocess(struct knote *kn, struct filt_process_s *data, struct kevent_
        revents = necp_fd_poll(fd_data, POLLIN, NULL, current_proc(), 1);
        res = ((revents & POLLIN) != 0);
        if (res) {
-               *kev = kn->kn_kevent;
+               knote_fill_kevent(kn, kev, 0);
        }
        NECP_FD_UNLOCK(fd_data);
-       return (res);
+       return res;
 }
 
 static int
-necp_fd_knrtouch(struct knote *kn, struct kevent_internal_s *kev)
+necp_fd_knrtouch(struct knote *kn, struct kevent_qos_s *kev)
 {
 #pragma unused(kev)
        struct necp_fd_data *fd_data;
@@ -626,12 +820,10 @@ necp_fd_knrtouch(struct knote *kn, struct kevent_internal_s *kev)
        fd_data = (struct necp_fd_data *)kn->kn_hook;
 
        NECP_FD_LOCK(fd_data);
-       if ((kn->kn_status & KN_UDATA_SPECIFIC) == 0)
-               kn->kn_udata = kev->udata;
        revents = necp_fd_poll(fd_data, POLLIN, NULL, current_proc(), 1);
        NECP_FD_UNLOCK(fd_data);
 
-       return ((revents & POLLIN) != 0);
+       return (revents & POLLIN) != 0;
 }
 
 SECURITY_READ_ONLY_EARLY(struct filterops) necp_fd_rfiltops = {
@@ -644,25 +836,22 @@ SECURITY_READ_ONLY_EARLY(struct filterops) necp_fd_rfiltops = {
 
 static int
 necpop_kqfilter(struct fileproc *fp, struct knote *kn,
-               __unused struct kevent_internal_s *kev, vfs_context_t ctx)
+    __unused struct kevent_qos_s *kev)
 {
-#pragma unused(fp, ctx)
        struct necp_fd_data *fd_data = NULL;
        int revents;
 
        if (kn->kn_filter != EVFILT_READ) {
                NECPLOG(LOG_ERR, "bad filter request %d", kn->kn_filter);
-               kn->kn_flags = EV_ERROR;
-               kn->kn_data = EINVAL;
-               return (0);
+               knote_set_error(kn, EINVAL);
+               return 0;
        }
 
-       fd_data = (struct necp_fd_data *)kn->kn_fp->f_fglob->fg_data;
+       fd_data = (struct necp_fd_data *)fp->f_fglob->fg_data;
        if (fd_data == NULL) {
                NECPLOG0(LOG_ERR, "No channel for kqfilter");
-               kn->kn_flags = EV_ERROR;
-               kn->kn_data = ENOENT;
-               return (0);
+               knote_set_error(kn, ENOENT);
+               return 0;
        }
 
        NECP_FD_LOCK(fd_data);
@@ -674,55 +863,49 @@ necpop_kqfilter(struct fileproc *fp, struct knote *kn,
 
        NECP_FD_UNLOCK(fd_data);
 
-       return ((revents & POLLIN) != 0);
+       return (revents & POLLIN) != 0;
 }
 
+#define INTERFACE_FLAGS_SHIFT   32
+#define INTERFACE_FLAGS_MASK    0xffff
+#define INTERFACE_INDEX_SHIFT   0
+#define INTERFACE_INDEX_MASK    0xffffffff
 
-static bool
-necp_set_client_defunct(struct necp_client *client)
+static uint64_t
+combine_interface_details(uint32_t interface_index, uint16_t interface_flags)
 {
-       bool updated = FALSE;
-       u_int32_t flags = 0;
-       u_int32_t value_size = 0;
-
-       client->defunct = TRUE;
-
-       u_int8_t *flags_pointer = necp_buffer_get_tlv_value(client->result, 0, &value_size);
-       if (flags_pointer && value_size == sizeof(flags)) {
-               memcpy(&flags, flags_pointer, value_size);
-
-               flags |= NECP_CLIENT_RESULT_FLAG_DEFUNCT;
-
-               (void)necp_buffer_write_tlv_if_different(client->result, NECP_CLIENT_RESULT_FLAGS,
-                                                                                                sizeof(flags), &flags, &updated, client->result, sizeof(client->result));
-       }
-
-       return (updated);
+       return ((uint64_t)interface_flags & INTERFACE_FLAGS_MASK) << INTERFACE_FLAGS_SHIFT |
+              ((uint64_t)interface_index & INTERFACE_INDEX_MASK) << INTERFACE_INDEX_SHIFT;
 }
 
+
 static void
-necp_defunct_client_for_policy(struct necp_client *client,
-                                                          struct _necp_client_defunct_list *defunct_list)
+necp_defunct_flow_registration(struct necp_client *client,
+    struct necp_client_flow_registration *flow_registration,
+    struct _necp_flow_defunct_list *defunct_list)
 {
-       if (!client->defunct) {
+       NECP_CLIENT_ASSERT_LOCKED(client);
+
+       if (!flow_registration->defunct) {
                bool needs_defunct = false;
                struct necp_client_flow *search_flow = NULL;
-               LIST_FOREACH(search_flow, &client->flow_list, flow_chain) {
+               LIST_FOREACH(search_flow, &flow_registration->flow_list, flow_chain) {
                        if (search_flow->nexus &&
-                               !uuid_is_null(search_flow->u.nexus_agent) &&
-                               search_flow->requested_nexus) {
-
+                           !uuid_is_null(search_flow->u.nexus_agent)) {
                                // Save defunct values for the nexus
                                if (defunct_list != NULL) {
                                        // Sleeping alloc won't fail; copy only what's necessary
-                                       struct necp_client_defunct *client_defunct = _MALLOC(sizeof (struct necp_client_defunct),
-                                                                                                                                                M_NECP, M_WAITOK | M_ZERO);
-                                       uuid_copy(client_defunct->nexus_agent, search_flow->u.nexus_agent);
-                                       uuid_copy(client_defunct->client_id, client->client_id);
-                                       client_defunct->proc_pid = client->proc_pid;
-
+                                       struct necp_flow_defunct *flow_defunct = _MALLOC(sizeof(struct necp_flow_defunct),
+                                           M_NECP, M_WAITOK | M_ZERO);
+                                       uuid_copy(flow_defunct->nexus_agent, search_flow->u.nexus_agent);
+                                       uuid_copy(flow_defunct->flow_id, ((flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_USE_CLIENT_ID) ?
+                                           client->client_id :
+                                           flow_registration->registration_id));
+                                       flow_defunct->proc_pid = client->proc_pid;
+                                       flow_defunct->agent_handle = client->agent_handle;
+                                       flow_defunct->flags = flow_registration->flags;
                                        // Add to the list provided by caller
-                                       LIST_INSERT_HEAD(defunct_list, client_defunct, chain);
+                                       LIST_INSERT_HEAD(defunct_list, flow_defunct, chain);
                                }
 
                                needs_defunct = true;
@@ -730,12 +913,25 @@ necp_defunct_client_for_policy(struct necp_client *client,
                }
 
                if (needs_defunct) {
+
                        // Only set defunct if there was some assigned flow
-                       client->defunct = true;
+                       flow_registration->defunct = true;
                }
        }
 }
 
+static void
+necp_defunct_client_for_policy(struct necp_client *client,
+    struct _necp_flow_defunct_list *defunct_list)
+{
+       NECP_CLIENT_ASSERT_LOCKED(client);
+
+       struct necp_client_flow_registration *flow_registration = NULL;
+       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+               necp_defunct_flow_registration(client, flow_registration, defunct_list);
+       }
+}
+
 static void
 necp_client_free(struct necp_client *client)
 {
@@ -743,6 +939,9 @@ necp_client_free(struct necp_client *client)
 
        NECP_CLIENT_UNLOCK(client);
 
+       FREE(client->extra_interface_options, M_NECP);
+       client->extra_interface_options = NULL;
+
        lck_mtx_destroy(&client->route_lock, necp_fd_mtx_grp);
        lck_mtx_destroy(&client->lock, necp_fd_mtx_grp);
 
@@ -754,33 +953,35 @@ necp_client_retain_locked(struct necp_client *client)
 {
        NECP_CLIENT_ASSERT_LOCKED(client);
 
-       client->reference_count++;
-       ASSERT(client->reference_count != 0);
+       os_ref_retain_locked(&client->reference_count);
 }
 
-static void
-necp_client_retain(struct necp_client *client)
-{
-       NECP_CLIENT_LOCK(client);
-       necp_client_retain_locked(client);
-       NECP_CLIENT_UNLOCK(client);
-}
 
 static bool
 necp_client_release_locked(struct necp_client *client)
 {
        NECP_CLIENT_ASSERT_LOCKED(client);
 
-       uint32_t old_ref = client->reference_count;
-
-       ASSERT(client->reference_count != 0);
-       if (--client->reference_count == 0) {
+       os_ref_count_t count = os_ref_release_locked(&client->reference_count);
+       if (count == 0) {
                necp_client_free(client);
        }
 
-       return (old_ref == 1);
+       return count == 0;
 }
 
+static bool
+necp_client_release(struct necp_client *client)
+{
+       bool last_ref;
+
+       NECP_CLIENT_LOCK(client);
+       if (!(last_ref = necp_client_release_locked(client))) {
+               NECP_CLIENT_UNLOCK(client);
+       }
+
+       return last_ref;
+}
 
 static void
 necp_client_update_observer_add_internal(struct necp_fd_data *observer_fd, struct necp_client *client)
@@ -793,7 +994,7 @@ necp_client_update_observer_add_internal(struct necp_fd_data *observer_fd, struc
        }
 
        struct necp_client_update *client_update = _MALLOC(sizeof(struct necp_client_update) + client->parameters_length,
-                                                                                                          M_NECP, M_WAITOK | M_ZERO);
+           M_NECP, M_WAITOK | M_ZERO);
        if (client_update != NULL) {
                client_update->update_length = sizeof(struct necp_client_observer_update) + client->parameters_length;
                uuid_copy(client_update->client_id, client->client_id);
@@ -819,7 +1020,7 @@ necp_client_update_observer_update_internal(struct necp_fd_data *observer_fd, st
        }
 
        struct necp_client_update *client_update = _MALLOC(sizeof(struct necp_client_update) + client->result_length,
-                                                                                                          M_NECP, M_WAITOK | M_ZERO);
+           M_NECP, M_WAITOK | M_ZERO);
        if (client_update != NULL) {
                client_update->update_length = sizeof(struct necp_client_observer_update) + client->result_length;
                uuid_copy(client_update->client_id, client->client_id);
@@ -845,7 +1046,7 @@ necp_client_update_observer_remove_internal(struct necp_fd_data *observer_fd, st
        }
 
        struct necp_client_update *client_update = _MALLOC(sizeof(struct necp_client_update),
-                                                                                                          M_NECP, M_WAITOK | M_ZERO);
+           M_NECP, M_WAITOK | M_ZERO);
        if (client_update != NULL) {
                client_update->update_length = sizeof(struct necp_client_observer_update);
                uuid_copy(client_update->client_id, client->client_id);
@@ -917,34 +1118,39 @@ necp_client_update_observer_remove(struct necp_client *client)
 }
 
 static void
-necp_destroy_client(struct necp_client *client, pid_t pid, bool abort)
+necp_destroy_client_flow_registration(struct necp_client *client,
+    struct necp_client_flow_registration *flow_registration,
+    pid_t pid, bool abort)
 {
-       NECP_CLIENT_ASSERT_UNLOCKED(client);
-
-       necp_client_update_observer_remove(client);
-
-       NECP_CLIENT_LOCK(client);
+       NECP_CLIENT_ASSERT_LOCKED(client);
 
-       // Free route
-       NECP_CLIENT_ROUTE_LOCK(client);
-       if (client->current_route != NULL) {
-               rtfree(client->current_route);
-               client->current_route = NULL;
-       }
-       NECP_CLIENT_ROUTE_UNLOCK(client);
+       bool has_close_parameters = false;
+       struct necp_client_agent_parameters close_parameters = {};
+       memset(close_parameters.u.close_token, 0, sizeof(close_parameters.u.close_token));
 
-       // Remove flow assignments
        struct necp_client_flow *search_flow = NULL;
        struct necp_client_flow *temp_flow = NULL;
-       LIST_FOREACH_SAFE(search_flow, &client->flow_list, flow_chain, temp_flow) {
+       LIST_FOREACH_SAFE(search_flow, &flow_registration->flow_list, flow_chain, temp_flow) {
                if (search_flow->nexus &&
-                       !uuid_is_null(search_flow->u.nexus_agent) &&
-                       search_flow->requested_nexus) {
+                   !uuid_is_null(search_flow->u.nexus_agent)) {
                        // Note that if we had defuncted the client earlier, this would result in a harmless ENOENT
-                       int netagent_error = netagent_client_message(search_flow->u.nexus_agent, client->client_id, pid,
-                           abort ? NETAGENT_MESSAGE_TYPE_ABORT_NEXUS : NETAGENT_MESSAGE_TYPE_CLOSE_NEXUS);
+                       u_int8_t message_type = (abort ? NETAGENT_MESSAGE_TYPE_ABORT_NEXUS :
+                           NETAGENT_MESSAGE_TYPE_CLOSE_NEXUS);
+                       if (((flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_BROWSE) ||
+                           (flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_RESOLVE)) &&
+                           !(flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_ALLOW_NEXUS)) {
+                               message_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
+                       }
+                       int netagent_error = netagent_client_message_with_params(search_flow->u.nexus_agent,
+                           ((flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_USE_CLIENT_ID) ?
+                           client->client_id :
+                           flow_registration->registration_id),
+                           pid, client->agent_handle,
+                           message_type,
+                           has_close_parameters ? &close_parameters : NULL,
+                           NULL, 0);
                        if (netagent_error != 0 && netagent_error != ENOENT) {
-                               NECPLOG(LOG_ERR, "necp_client_remove close nexus error (%d)", netagent_error);
+                               NECPLOG(LOG_ERR, "necp_client_remove close nexus error (%d) MESSAGE TYPE %u", netagent_error, message_type);
                        }
                        uuid_clear(search_flow->u.nexus_agent);
                }
@@ -958,17 +1164,49 @@ necp_destroy_client(struct necp_client *client, pid_t pid, bool abort)
                } else {
                        OSDecrementAtomic(&necp_if_flow_count);
                }
-               zfree(necp_flow_zone, search_flow);
+               mcache_free(necp_flow_cache, search_flow);
+       }
+
+       RB_REMOVE(_necp_client_flow_tree, &client->flow_registrations, flow_registration);
+       flow_registration->client = NULL;
+
+       mcache_free(necp_flow_registration_cache, flow_registration);
+}
+
+static void
+necp_destroy_client(struct necp_client *client, pid_t pid, bool abort)
+{
+       NECP_CLIENT_ASSERT_UNLOCKED(client);
+
+       necp_client_update_observer_remove(client);
+
+       NECP_CLIENT_LOCK(client);
+
+       // Free route
+       NECP_CLIENT_ROUTE_LOCK(client);
+       if (client->current_route != NULL) {
+               rtfree(client->current_route);
+               client->current_route = NULL;
+       }
+       NECP_CLIENT_ROUTE_UNLOCK(client);
+
+       // Remove flow assignments
+       struct necp_client_flow_registration *flow_registration = NULL;
+       struct necp_client_flow_registration *temp_flow_registration = NULL;
+       RB_FOREACH_SAFE(flow_registration, _necp_client_flow_tree, &client->flow_registrations, temp_flow_registration) {
+               necp_destroy_client_flow_registration(client, flow_registration, pid, abort);
        }
 
+
        // Remove agent assertions
        struct necp_client_assertion *search_assertion = NULL;
        struct necp_client_assertion *temp_assertion = NULL;
        LIST_FOREACH_SAFE(search_assertion, &client->assertion_list, assertion_chain, temp_assertion) {
-               int netagent_error = netagent_client_message(search_assertion->asserted_netagent, client->client_id, pid, NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT);
+               int netagent_error = netagent_client_message(search_assertion->asserted_netagent, client->client_id, pid,
+                   client->agent_handle, NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT);
                if (netagent_error != 0) {
                        NECPLOG((netagent_error == ENOENT ? LOG_DEBUG : LOG_ERR),
-                                       "necp_client_remove unassert agent error (%d)", netagent_error);
+                           "necp_client_remove unassert agent error (%d)", netagent_error);
                }
                LIST_REMOVE(search_assertion, assertion_chain);
                FREE(search_assertion, M_NECP);
@@ -1008,6 +1246,16 @@ necpop_close(struct fileglob *fg, vfs_context_t ctx)
 
                NECP_FD_LOCK(fd_data);
                pid_t pid = fd_data->proc_pid;
+
+               struct necp_client_flow_registration *flow_registration = NULL;
+               struct necp_client_flow_registration *temp_flow_registration = NULL;
+               RB_FOREACH_SAFE(flow_registration, _necp_fd_flow_tree, &fd_data->flows, temp_flow_registration) {
+                       NECP_FLOW_TREE_LOCK_EXCLUSIVE();
+                       RB_REMOVE(_necp_client_flow_global_tree, &necp_client_flow_global_tree, flow_registration);
+                       NECP_FLOW_TREE_UNLOCK();
+                       RB_REMOVE(_necp_fd_flow_tree, &fd_data->flows, flow_registration);
+               }
+
                struct necp_client *client = NULL;
                struct necp_client *temp_client = NULL;
                RB_FOREACH_SAFE(client, _necp_client_tree, &fd_data->clients, temp_client) {
@@ -1049,7 +1297,7 @@ necpop_close(struct fileglob *fg, vfs_context_t ctx)
                }
        }
 
-       return (error);
+       return error;
 }
 
 /// NECP client utilities
@@ -1057,8 +1305,8 @@ necpop_close(struct fileglob *fg, vfs_context_t ctx)
 static inline bool
 necp_address_is_wildcard(const union necp_sockaddr_union * const addr)
 {
-       return ((addr->sa.sa_family == AF_INET && addr->sin.sin_addr.s_addr == INADDR_ANY) ||
-                       (addr->sa.sa_family == AF_INET6 && IN6_IS_ADDR_UNSPECIFIED(&addr->sin6.sin6_addr)));
+       return (addr->sa.sa_family == AF_INET && addr->sin.sin_addr.s_addr == INADDR_ANY) ||
+              (addr->sa.sa_family == AF_INET6 && IN6_IS_ADDR_UNSPECIFIED(&addr->sin6.sin6_addr));
 }
 
 static int
@@ -1079,259 +1327,484 @@ necp_find_fd_data(int fd, struct necp_fd_data **fd_data)
        }
        *fd_data = (struct necp_fd_data *)fp->f_fglob->fg_data;
 
+       if ((*fd_data)->necp_fd_type != necp_fd_type_client) {
+               // Not a client fd, ignore
+               fp_drop(p, fd, fp, 1);
+               error = EINVAL;
+               goto done;
+       }
+
 done:
        proc_fdunlock(p);
-       return (error);
+       return error;
 }
 
 
-static void
-necp_client_add_socket_flow(struct necp_client *client, struct inpcb *inp)
-{
-       struct necp_client_flow *new_flow = zalloc(necp_flow_zone);
-       if (new_flow == NULL) {
-               NECPLOG0(LOG_ERR, "Failed to allocate socket flow");
-               return;
-       }
-
-       memset(new_flow, 0, sizeof(*new_flow));
-
-       new_flow->socket = TRUE;
-       new_flow->u.socket_handle = inp;
-       new_flow->u.cb = inp->necp_cb;
-
-       OSIncrementAtomic(&necp_socket_flow_count);
-
-       LIST_INSERT_HEAD(&client->flow_list, new_flow, flow_chain);
-}
-
-static void
-necp_client_add_interface_flow(struct necp_client *client, uint32_t interface_index)
+static struct necp_client_flow *
+necp_client_add_interface_flow(struct necp_client_flow_registration *flow_registration,
+    uint32_t interface_index)
 {
-       struct necp_client_flow *new_flow = zalloc(necp_flow_zone);
+       struct necp_client_flow *new_flow = mcache_alloc(necp_flow_cache, MCR_SLEEP);
        if (new_flow == NULL) {
                NECPLOG0(LOG_ERR, "Failed to allocate interface flow");
-               return;
+               return NULL;
        }
 
        memset(new_flow, 0, sizeof(*new_flow));
 
        // Neither nexus nor socket
        new_flow->interface_index = interface_index;
-       new_flow->u.socket_handle = client->interface_handle;
-       new_flow->u.cb = client->interface_cb;
+       new_flow->u.socket_handle = flow_registration->interface_handle;
+       new_flow->u.cb = flow_registration->interface_cb;
 
        OSIncrementAtomic(&necp_if_flow_count);
 
-       LIST_INSERT_HEAD(&client->flow_list, new_flow, flow_chain);
+       LIST_INSERT_HEAD(&flow_registration->flow_list, new_flow, flow_chain);
+
+       return new_flow;
 }
 
-static void
-necp_client_add_interface_flow_if_needed(struct necp_client *client, uint32_t interface_index)
+static struct necp_client_flow *
+necp_client_add_interface_flow_if_needed(struct necp_client *client,
+    struct necp_client_flow_registration *flow_registration,
+    uint32_t interface_index)
 {
        if (!client->allow_multiple_flows ||
-               interface_index == IFSCOPE_NONE) {
+           interface_index == IFSCOPE_NONE) {
                // Interface not set, or client not allowed to use this mode
-               return;
+               return NULL;
        }
 
        struct necp_client_flow *flow = NULL;
-       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
+       LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
                if (!flow->nexus && !flow->socket && flow->interface_index == interface_index) {
                        // Already have the flow
                        flow->invalid = FALSE;
-
-                       flow->u.socket_handle = client->interface_handle;
-                       flow->u.cb = client->interface_cb;
-                       return;
+                       flow->u.socket_handle = flow_registration->interface_handle;
+                       flow->u.cb = flow_registration->interface_cb;
+                       return NULL;
                }
        }
-
-       necp_client_add_interface_flow(client, interface_index);
-}
-
-static bool
-necp_client_flow_is_viable(proc_t proc, struct necp_client *client,
-                                               struct necp_client_flow *flow)
-{
-       struct necp_aggregate_result result;
-       bool ignore_address = (client->allow_multiple_flows && !flow->nexus && !flow->socket);
-
-       flow->necp_flow_flags = 0;
-       int error = necp_application_find_policy_match_internal(proc, client->parameters,
-                                                                                                                       (u_int32_t)client->parameters_length,
-                                                                                                                       &result, &flow->necp_flow_flags,
-                                                                                                                       flow->interface_index,
-                                                                                                                       &flow->local_addr, &flow->remote_addr, NULL, ignore_address);
-
-       return (error == 0 &&
-                       result.routed_interface_index != IFSCOPE_NONE &&
-                       result.routing_result != NECP_KERNEL_POLICY_RESULT_DROP);
+       return necp_client_add_interface_flow(flow_registration, interface_index);
 }
 
-static bool
-necp_client_update_flows(proc_t proc, struct necp_client *client)
+static void
+necp_client_add_interface_option_if_needed(struct necp_client *client,
+    uint32_t interface_index,
+    uint32_t interface_generation,
+    uuid_t *nexus_agent)
 {
-       bool client_updated = FALSE;
-       struct necp_client_flow *flow = NULL;
-       struct necp_client_flow *temp_flow = NULL;
-       LIST_FOREACH_SAFE(flow, &client->flow_list, flow_chain, temp_flow) {
-               // Check policy result for flow
-               int old_flags = flow->necp_flow_flags;
-               bool viable = necp_client_flow_is_viable(proc, client, flow);
-
-               // TODO: Defunct nexus flows that are blocked by policy
+       if (interface_index == IFSCOPE_NONE ||
+           (client->interface_option_count != 0 && !client->allow_multiple_flows)) {
+               // Interface not set, or client not allowed to use this mode
+               return;
+       }
 
-               if (flow->viable != viable) {
-                       flow->viable = viable;
-                       client_updated = TRUE;
-               }
+       if (client->interface_option_count >= NECP_CLIENT_MAX_INTERFACE_OPTIONS) {
+               // Cannot take any more interface options
+               return;
+       }
 
-               if ((old_flags & (NECP_CLIENT_RESULT_FLAG_HAS_IPV4 | NECP_CLIENT_RESULT_FLAG_HAS_IPV6)) !=
-                   (flow->necp_flow_flags & (NECP_CLIENT_RESULT_FLAG_HAS_IPV4 | NECP_CLIENT_RESULT_FLAG_HAS_IPV6))) {
-                       client_updated = TRUE;
+       // Check if already present
+       for (u_int32_t option_i = 0; option_i < client->interface_option_count; option_i++) {
+               if (option_i < NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT) {
+                       struct necp_client_interface_option *option = &client->interface_options[option_i];
+                       if (option->interface_index == interface_index) {
+                               if (nexus_agent == NULL) {
+                                       return;
+                               }
+                               if (uuid_compare(option->nexus_agent, *nexus_agent) == 0) {
+                                       return;
+                               }
+                               if (uuid_is_null(option->nexus_agent)) {
+                                       uuid_copy(option->nexus_agent, *nexus_agent);
+                                       return;
+                               }
+                               // If we get to this point, this is a new nexus flow
+                       }
+               } else {
+                       struct necp_client_interface_option *option = &client->extra_interface_options[option_i - NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT];
+                       if (option->interface_index == interface_index) {
+                               if (nexus_agent == NULL) {
+                                       return;
+                               }
+                               if (uuid_compare(option->nexus_agent, *nexus_agent) == 0) {
+                                       return;
+                               }
+                               if (uuid_is_null(option->nexus_agent)) {
+                                       uuid_copy(option->nexus_agent, *nexus_agent);
+                                       return;
+                               }
+                               // If we get to this point, this is a new nexus flow
+                       }
                }
+       }
 
-               if (flow->viable && client_updated && (flow->socket || (!flow->socket && !flow->nexus)) && flow->u.cb) {
-                       flow->u.cb(flow->u.socket_handle, NECP_CLIENT_CBACTION_VIABLE, flow);
+       // Add a new entry
+       if (client->interface_option_count < NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT) {
+               // Add to static
+               struct necp_client_interface_option *option = &client->interface_options[client->interface_option_count];
+               option->interface_index = interface_index;
+               option->interface_generation = interface_generation;
+               if (nexus_agent != NULL) {
+                       uuid_copy(option->nexus_agent, *nexus_agent);
+               } else {
+                       uuid_clear(option->nexus_agent);
                }
+               client->interface_option_count++;
+       } else {
+               // Add to extra
+               if (client->extra_interface_options == NULL) {
+                       client->extra_interface_options = _MALLOC(sizeof(struct necp_client_interface_option) * NECP_CLIENT_INTERFACE_OPTION_EXTRA_COUNT, M_NECP, M_WAITOK | M_ZERO);
+               }
+               if (client->extra_interface_options != NULL) {
+                       struct necp_client_interface_option *option = &client->extra_interface_options[client->interface_option_count - NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT];
+                       option->interface_index = interface_index;
+                       option->interface_generation = interface_generation;
+                       if (nexus_agent != NULL) {
+                               uuid_copy(option->nexus_agent, *nexus_agent);
+                       } else {
+                               uuid_clear(option->nexus_agent);
+                       }
+                       client->interface_option_count++;
+               }
+       }
+}
+
+static bool
+necp_client_flow_is_viable(proc_t proc, struct necp_client *client,
+    struct necp_client_flow *flow)
+{
+       struct necp_aggregate_result result;
+       bool ignore_address = (client->allow_multiple_flows && !flow->nexus && !flow->socket);
+
+       flow->necp_flow_flags = 0;
+       int error = necp_application_find_policy_match_internal(proc, client->parameters,
+           (u_int32_t)client->parameters_length,
+           &result, &flow->necp_flow_flags, NULL,
+           flow->interface_index,
+           &flow->local_addr, &flow->remote_addr, NULL, NULL,
+           NULL, ignore_address, true, NULL);
+
+       // Check for blocking agents
+       for (int i = 0; i < NECP_MAX_NETAGENTS; i++) {
+               if (uuid_is_null(result.netagents[i])) {
+                       // Passed end of valid agents
+                       break;
+               }
+
+               u_int32_t flags = netagent_get_flags(result.netagents[i]);
+               if ((flags & NETAGENT_FLAG_REGISTERED) &&
+                   !(flags & NETAGENT_FLAG_VOLUNTARY) &&
+                   !(flags & NETAGENT_FLAG_ACTIVE) &&
+                   !(flags & NETAGENT_FLAG_SPECIFIC_USE_ONLY)) {
+                       // A required agent is not active, cause the flow to be marked non-viable
+                       return false;
+               }
+       }
 
-               if (!flow->viable || flow->invalid) {
-                       if (client_updated && (flow->socket || (!flow->socket && !flow->nexus)) && flow->u.cb) {
-                               flow->u.cb(flow->u.socket_handle, NECP_CLIENT_CBACTION_NONVIABLE, flow);
+       return error == 0 &&
+              result.routed_interface_index != IFSCOPE_NONE &&
+              result.routing_result != NECP_KERNEL_POLICY_RESULT_DROP;
+}
+
+static void
+necp_flow_add_interface_flows(proc_t proc,
+    struct necp_client *client,
+    struct necp_client_flow_registration *flow_registration,
+    bool send_initial)
+{
+       // Traverse all interfaces and add a tracking flow if needed
+       for (u_int32_t option_i = 0; option_i < client->interface_option_count; option_i++) {
+               if (option_i < NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT) {
+                       struct necp_client_interface_option *option = &client->interface_options[option_i];
+                       struct necp_client_flow *flow = necp_client_add_interface_flow_if_needed(client, flow_registration, option->interface_index);
+                       if (flow != NULL && send_initial) {
+                               flow->viable = necp_client_flow_is_viable(proc, client, flow);
+                               if (flow->viable && flow->u.cb) {
+                                       bool viable = flow->viable;
+                                       flow->u.cb(flow_registration->interface_handle, NECP_CLIENT_CBACTION_INITIAL, flow->interface_index, flow->necp_flow_flags, &viable);
+                                       flow->viable = viable;
+                               }
+                       }
+               } else {
+                       struct necp_client_interface_option *option = &client->extra_interface_options[option_i - NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT];
+                       struct necp_client_flow *flow = necp_client_add_interface_flow_if_needed(client, flow_registration, option->interface_index);
+                       if (flow != NULL && send_initial) {
+                               flow->viable = necp_client_flow_is_viable(proc, client, flow);
+                               if (flow->viable && flow->u.cb) {
+                                       bool viable = flow->viable;
+                                       flow->u.cb(flow_registration->interface_handle, NECP_CLIENT_CBACTION_INITIAL, flow->interface_index, flow->necp_flow_flags, &viable);
+                                       flow->viable = viable;
+                               }
                        }
-                       // The callback might change the viable-flag of the
-                       // flow depending on its policy. Thus, we need to
-                       // check again the flags after the callback.
                }
+       }
+}
 
+static bool
+necp_client_update_flows(proc_t proc,
+    struct necp_client *client,
+    struct _necp_flow_defunct_list *defunct_list)
+{
+       NECP_CLIENT_ASSERT_LOCKED(client);
 
-               // Handle flows that no longer match
-               if (!flow->viable || flow->invalid) {
-                       // Drop them as long as they aren't assigned data
-                       if (!flow->requested_nexus && !flow->assigned) {
-                               if (flow->assigned_results != NULL) {
-                                       FREE(flow->assigned_results, M_NETAGENT);
-                                       flow->assigned_results = NULL;
-                                       client_updated = TRUE;
+       bool client_updated = FALSE;
+       struct necp_client_flow *flow = NULL;
+       struct necp_client_flow *temp_flow = NULL;
+       struct necp_client_flow_registration *flow_registration = NULL;
+       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+               if (flow_registration->interface_cb != NULL) {
+                       // Add any interface flows that are not already tracked
+                       necp_flow_add_interface_flows(proc, client, flow_registration, false);
+               }
+
+               LIST_FOREACH_SAFE(flow, &flow_registration->flow_list, flow_chain, temp_flow) {
+                       // Check policy result for flow
+                       int old_flags = flow->necp_flow_flags;
+                       bool viable = necp_client_flow_is_viable(proc, client, flow);
+
+                       // TODO: Defunct nexus flows that are blocked by policy
+
+                       if (flow->viable != viable) {
+                               flow->viable = viable;
+                               client_updated = TRUE;
+                       }
+
+                       if ((old_flags & NECP_CLIENT_RESULT_FLAG_FORCE_UPDATE) !=
+                           (flow->necp_flow_flags & NECP_CLIENT_RESULT_FLAG_FORCE_UPDATE)) {
+                               client_updated = TRUE;
+                       }
+
+                       if (flow->viable && client_updated && (flow->socket || (!flow->socket && !flow->nexus)) && flow->u.cb) {
+                               bool flow_viable = flow->viable;
+                               flow->u.cb(flow->u.socket_handle, NECP_CLIENT_CBACTION_VIABLE, flow->interface_index, flow->necp_flow_flags, &flow_viable);
+                               flow->viable = flow_viable;
+                       }
+
+                       if (!flow->viable || flow->invalid) {
+                               if (client_updated && (flow->socket || (!flow->socket && !flow->nexus)) && flow->u.cb) {
+                                       bool flow_viable = flow->viable;
+                                       flow->u.cb(flow->u.socket_handle, NECP_CLIENT_CBACTION_NONVIABLE, flow->interface_index, flow->necp_flow_flags, &flow_viable);
+                                       flow->viable = flow_viable;
                                }
-                               LIST_REMOVE(flow, flow_chain);
-                               if (flow->socket) {
-                                       OSDecrementAtomic(&necp_socket_flow_count);
-                               } else {
-                                       OSDecrementAtomic(&necp_if_flow_count);
+                               // The callback might change the viable-flag of the
+                               // flow depending on its policy. Thus, we need to
+                               // check the flags again after the callback.
+                       }
+
+                       (void)defunct_list;
+
+                       // Handle flows that no longer match
+                       if (!flow->viable || flow->invalid) {
+                               // Drop them as long as they aren't assigned data
+                               if (!flow->nexus && !flow->assigned) {
+                                       if (flow->assigned_results != NULL) {
+                                               FREE(flow->assigned_results, M_NETAGENT);
+                                               flow->assigned_results = NULL;
+                                               client_updated = TRUE;
+                                       }
+                                       LIST_REMOVE(flow, flow_chain);
+                                       if (flow->socket) {
+                                               OSDecrementAtomic(&necp_socket_flow_count);
+                                       } else {
+                                               OSDecrementAtomic(&necp_if_flow_count);
+                                       }
+                                       mcache_free(necp_flow_cache, flow);
                                }
-                               zfree(necp_flow_zone, flow);
                        }
                }
        }
 
-       return (client_updated);
+       return client_updated;
 }
 
 static void
 necp_client_mark_all_nonsocket_flows_as_invalid(struct necp_client *client)
 {
+       struct necp_client_flow_registration *flow_registration = NULL;
        struct necp_client_flow *flow = NULL;
-       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-               if (!flow->socket) { // Socket flows are not marked as invalid
-                       flow->invalid = TRUE;
+       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+               LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
+                       if (!flow->socket) { // Socket flows are not marked as invalid
+                               flow->invalid = TRUE;
+                       }
                }
        }
+
+       // Reset option count every update
+       client->interface_option_count = 0;
 }
 
-static bool
-necp_netagent_applies_to_client(__unused struct necp_client *client,
-                                                               const struct necp_client_parsed_parameters *parameters,
-                                                               uuid_t netagent_uuid, bool allow_nexus,
-                                                               uint32_t interface_index, u_int16_t interface_flags)
+static inline bool
+necp_netagent_is_required(const struct necp_client_parsed_parameters *parameters,
+    uuid_t *netagent_uuid)
 {
-#pragma unused(interface_index, interface_flags)
-       bool applies = FALSE;
-       u_int32_t flags = netagent_get_flags(netagent_uuid);
-       if (!(flags & NETAGENT_FLAG_REGISTERED)) {
-               // Unregistered agents never apply
-               return (applies);
-       }
+       // Specific use agents only apply when required
+       bool required = false;
+       if (parameters != NULL) {
+               // Check required agent UUIDs
+               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                       if (uuid_is_null(parameters->required_netagents[i])) {
+                               break;
+                       }
+                       if (uuid_compare(parameters->required_netagents[i], *netagent_uuid) == 0) {
+                               required = true;
+                               break;
+                       }
+               }
 
-       if (!allow_nexus &&
-               (flags & NETAGENT_FLAG_NEXUS_PROVIDER)) {
-               // Hide nexus providers unless allowed
-               // Direct interfaces and direct policies are allowed to use a nexus
-               // Delegate interfaces or re-scoped interfaces are not allowed
-               return (applies);
-       }
+               if (!required) {
+                       // Check required agent types
+                       bool fetched_type = false;
+                       char netagent_domain[NETAGENT_DOMAINSIZE];
+                       char netagent_type[NETAGENT_TYPESIZE];
+                       memset(&netagent_domain, 0, NETAGENT_DOMAINSIZE);
+                       memset(&netagent_type, 0, NETAGENT_TYPESIZE);
 
-       if (flags & NETAGENT_FLAG_SPECIFIC_USE_ONLY) {
-               // Specific use agents only apply when required
-               bool required = FALSE;
-               if (parameters != NULL) {
-                       // Check required agent UUIDs
-                       for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
-                               if (uuid_is_null(parameters->required_netagents[i])) {
+                       for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                               if (strlen(parameters->required_netagent_types[i].netagent_domain) == 0 ||
+                                   strlen(parameters->required_netagent_types[i].netagent_type) == 0) {
                                        break;
                                }
-                               if (uuid_compare(parameters->required_netagents[i], netagent_uuid) == 0) {
-                                       required = TRUE;
-                                       break;
-                               }
-                       }
 
-                       if (!required) {
-                               // Check required agent types
-                               bool fetched_type = FALSE;
-                               char netagent_domain[NETAGENT_DOMAINSIZE];
-                               char netagent_type[NETAGENT_TYPESIZE];
-                               memset(&netagent_domain, 0, NETAGENT_DOMAINSIZE);
-                               memset(&netagent_type, 0, NETAGENT_TYPESIZE);
-
-                               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
-                                       if (strlen(parameters->required_netagent_types[i].netagent_domain) == 0 ||
-                                               strlen(parameters->required_netagent_types[i].netagent_type) == 0) {
+                               if (!fetched_type) {
+                                       if (netagent_get_agent_domain_and_type(*netagent_uuid, netagent_domain, netagent_type)) {
+                                               fetched_type = TRUE;
+                                       } else {
                                                break;
                                        }
+                               }
 
-                                       if (!fetched_type) {
-                                               if (netagent_get_agent_domain_and_type(netagent_uuid, netagent_domain, netagent_type)) {
-                                                       fetched_type = TRUE;
-                                               } else {
-                                                       break;
-                                               }
-                                       }
-
-                                       if ((strlen(parameters->required_netagent_types[i].netagent_domain) == 0 ||
-                                                strncmp(netagent_domain, parameters->required_netagent_types[i].netagent_domain, NETAGENT_DOMAINSIZE) == 0) &&
-                                               (strlen(parameters->required_netagent_types[i].netagent_type) == 0 ||
-                                                strncmp(netagent_type, parameters->required_netagent_types[i].netagent_type, NETAGENT_TYPESIZE) == 0)) {
-                                               required = TRUE;
-                                               break;
-                                       }
+                               if ((strlen(parameters->required_netagent_types[i].netagent_domain) == 0 ||
+                                   strncmp(netagent_domain, parameters->required_netagent_types[i].netagent_domain, NETAGENT_DOMAINSIZE) == 0) &&
+                                   (strlen(parameters->required_netagent_types[i].netagent_type) == 0 ||
+                                   strncmp(netagent_type, parameters->required_netagent_types[i].netagent_type, NETAGENT_TYPESIZE) == 0)) {
+                                       required = true;
+                                       break;
                                }
                        }
                }
+       }
+
+       return required;
+}
+
+static bool
+necp_netagent_applies_to_client(struct necp_client *client,
+    const struct necp_client_parsed_parameters *parameters,
+    uuid_t *netagent_uuid, bool allow_nexus,
+    uint32_t interface_index, uint32_t interface_generation)
+{
+#pragma unused(interface_index, interface_generation)
+       bool applies = FALSE;
+       u_int32_t flags = netagent_get_flags(*netagent_uuid);
+       if (!(flags & NETAGENT_FLAG_REGISTERED)) {
+               // Unregistered agents never apply
+               return applies;
+       }
+
+       const bool is_nexus_agent = ((flags & NETAGENT_FLAG_NEXUS_PROVIDER) ||
+           (flags & NETAGENT_FLAG_NEXUS_LISTENER) ||
+           (flags & NETAGENT_FLAG_CUSTOM_ETHER_NEXUS) ||
+           (flags & NETAGENT_FLAG_CUSTOM_IP_NEXUS) ||
+           (flags & NETAGENT_FLAG_INTERPOSE_NEXUS));
+       if (is_nexus_agent) {
+               if (!allow_nexus) {
+                       // Hide nexus providers unless allowed
+                       // Direct interfaces and direct policies are allowed to use a nexus
+                       // Delegate interfaces or re-scoped interfaces are not allowed
+                       return applies;
+               }
+
+               if ((parameters->flags & NECP_CLIENT_PARAMETER_FLAG_CUSTOM_ETHER) &&
+                   !(flags & NETAGENT_FLAG_CUSTOM_ETHER_NEXUS)) {
+                       // Client requested a custom ether nexus, but this nexus isn't one
+                       return applies;
+               }
+
+               if ((parameters->flags & NECP_CLIENT_PARAMETER_FLAG_CUSTOM_IP) &&
+                   !(flags & NETAGENT_FLAG_CUSTOM_IP_NEXUS)) {
+                       // Client requested a custom IP nexus, but this nexus isn't one
+                       return applies;
+               }
+
+               if ((parameters->flags & NECP_CLIENT_PARAMETER_FLAG_INTERPOSE) &&
+                   !(flags & NETAGENT_FLAG_INTERPOSE_NEXUS)) {
+                       // Client requested an interpose nexus, but this nexus isn't one
+                       return applies;
+               }
 
-               applies = required;
+               if (!(parameters->flags & NECP_CLIENT_PARAMETER_FLAG_CUSTOM_ETHER) &&
+                   !(parameters->flags & NECP_CLIENT_PARAMETER_FLAG_CUSTOM_IP) &&
+                   !(parameters->flags & NECP_CLIENT_PARAMETER_FLAG_INTERPOSE) &&
+                   !(flags & NETAGENT_FLAG_NEXUS_PROVIDER)) {
+                       // Client requested default parameters, but this nexus isn't generic
+                       return applies;
+               }
+       }
+
+       if (uuid_compare(client->failed_trigger_agent.netagent_uuid, *netagent_uuid) == 0) {
+               if (client->failed_trigger_agent.generation == netagent_get_generation(*netagent_uuid)) {
+                       // If this agent was triggered, and failed, and hasn't changed, keep hiding it
+                       return applies;
+               } else {
+                       // Mismatch generation, clear out old trigger
+                       uuid_clear(client->failed_trigger_agent.netagent_uuid);
+                       client->failed_trigger_agent.generation = 0;
+               }
+       }
+
+       if (flags & NETAGENT_FLAG_SPECIFIC_USE_ONLY) {
+               // Specific use agents only apply when required
+               applies = necp_netagent_is_required(parameters, netagent_uuid);
        } else {
                applies = TRUE;
        }
 
 
-       return (applies);
+       return applies;
 }
 
 static void
-necp_client_add_agent_flows_for_interface(struct necp_client *client,
-                                                                                 const struct necp_client_parsed_parameters *parsed_parameters,
-                                                                                 ifnet_t ifp)
+necp_client_add_agent_interface_options(struct necp_client *client,
+    const struct necp_client_parsed_parameters *parsed_parameters,
+    ifnet_t ifp)
 {
        if (ifp != NULL && ifp->if_agentids != NULL) {
                for (u_int32_t i = 0; i < ifp->if_agentcount; i++) {
                        if (uuid_is_null(ifp->if_agentids[i])) {
                                continue;
                        }
-                       u_int16_t if_flags = nstat_ifnet_to_flags(ifp);
                        // Relies on the side effect that nexus agents that apply will create flows
-                       (void)necp_netagent_applies_to_client(client, parsed_parameters, ifp->if_agentids[i], TRUE, ifp->if_index, if_flags);
+                       (void)necp_netagent_applies_to_client(client, parsed_parameters, &ifp->if_agentids[i], TRUE,
+                           ifp->if_index, ifnet_get_generation(ifp));
+               }
+       }
+}
+
+static void
+necp_client_add_browse_interface_options(struct necp_client *client,
+    const struct necp_client_parsed_parameters *parsed_parameters,
+    ifnet_t ifp)
+{
+       if (ifp != NULL && ifp->if_agentids != NULL) {
+               for (u_int32_t i = 0; i < ifp->if_agentcount; i++) {
+                       if (uuid_is_null(ifp->if_agentids[i])) {
+                               continue;
+                       }
+
+                       u_int32_t flags = netagent_get_flags(ifp->if_agentids[i]);
+                       if ((flags & NETAGENT_FLAG_REGISTERED) &&
+                           (flags & NETAGENT_FLAG_ACTIVE) &&
+                           (flags & NETAGENT_FLAG_SUPPORTS_BROWSE) &&
+                           (!(flags & NETAGENT_FLAG_SPECIFIC_USE_ONLY) ||
+                           necp_netagent_is_required(parsed_parameters, &ifp->if_agentids[i]))) {
+                               necp_client_add_interface_option_if_needed(client, ifp->if_index, ifnet_get_generation(ifp), &ifp->if_agentids[i]);
+
+                               // Finding one is enough
+                               break;
+                       }
                }
        }
 }
@@ -1340,18 +1813,35 @@ static inline bool
 necp_client_address_is_valid(struct sockaddr *address)
 {
        if (address->sa_family == AF_INET) {
-               return (address->sa_len == sizeof(struct sockaddr_in));
+               return address->sa_len == sizeof(struct sockaddr_in);
        } else if (address->sa_family == AF_INET6) {
-               return (address->sa_len == sizeof(struct sockaddr_in6));
+               return address->sa_len == sizeof(struct sockaddr_in6);
+       } else {
+               return FALSE;
+       }
+}
+
+static inline bool
+necp_client_endpoint_is_unspecified(struct necp_client_endpoint *endpoint)
+{
+       if (necp_client_address_is_valid(&endpoint->u.sa)) {
+               if (endpoint->u.sa.sa_family == AF_INET) {
+                       return endpoint->u.sin.sin_addr.s_addr == INADDR_ANY;
+               } else if (endpoint->u.sa.sa_family == AF_INET6) {
+                       return IN6_IS_ADDR_UNSPECIFIED(&endpoint->u.sin6.sin6_addr);
+               } else {
+                       return TRUE;
+               }
        } else {
-               return (FALSE);
+               return TRUE;
        }
 }
 
+
 static int
 necp_client_parse_parameters(u_int8_t *parameters,
-                                                        u_int32_t parameters_size,
-                                                        struct necp_client_parsed_parameters *parsed_parameters)
+    u_int32_t parameters_size,
+    struct necp_client_parsed_parameters *parsed_parameters)
 {
        int error = 0;
        size_t offset = 0;
@@ -1361,12 +1851,19 @@ necp_client_parse_parameters(u_int8_t *parameters,
        u_int32_t num_required_agents = 0;
        u_int32_t num_prohibited_agents = 0;
        u_int32_t num_preferred_agents = 0;
+       u_int32_t num_avoided_agents = 0;
        u_int32_t num_required_agent_types = 0;
        u_int32_t num_prohibited_agent_types = 0;
        u_int32_t num_preferred_agent_types = 0;
+       u_int32_t num_avoided_agent_types = 0;
+       u_int8_t *resolver_tag = NULL;
+       u_int32_t resolver_tag_length = 0;
+       u_int8_t *client_hostname = NULL;
+       u_int32_t hostname_length = 0;
+       uuid_t parent_id = {};
 
        if (parsed_parameters == NULL) {
-               return (EINVAL);
+               return EINVAL;
        }
 
        memset(parsed_parameters, 0, sizeof(struct necp_client_parsed_parameters));
@@ -1385,211 +1882,286 @@ necp_client_parse_parameters(u_int8_t *parameters,
                        u_int8_t *value = necp_buffer_get_tlv_value(parameters, offset, NULL);
                        if (value != NULL) {
                                switch (type) {
-                                       case NECP_CLIENT_PARAMETER_BOUND_INTERFACE: {
-                                               if (length <= IFXNAMSIZ && length > 0) {
-                                                       ifnet_t bound_interface = NULL;
-                                                       char interface_name[IFXNAMSIZ];
-                                                       memcpy(interface_name, value, length);
-                                                       interface_name[length - 1] = 0; // Make sure the string is NULL terminated
-                                                       if (ifnet_find_by_name(interface_name, &bound_interface) == 0) {
-                                                               parsed_parameters->required_interface_index = bound_interface->if_index;
-                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF;
-                                                               ifnet_release(bound_interface);
-                                                       }
+                               case NECP_CLIENT_PARAMETER_BOUND_INTERFACE: {
+                                       if (length <= IFXNAMSIZ && length > 0) {
+                                               ifnet_t bound_interface = NULL;
+                                               char interface_name[IFXNAMSIZ];
+                                               memcpy(interface_name, value, length);
+                                               interface_name[length - 1] = 0;         // Make sure the string is NULL terminated
+                                               if (ifnet_find_by_name(interface_name, &bound_interface) == 0) {
+                                                       parsed_parameters->required_interface_index = bound_interface->if_index;
+                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF;
+                                                       ifnet_release(bound_interface);
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_LOCAL_ADDRESS: {
-                                               if (length >= sizeof(struct necp_policy_condition_addr)) {
-                                                       struct necp_policy_condition_addr *address_struct = (struct necp_policy_condition_addr *)(void *)value;
-                                                       if (necp_client_address_is_valid(&address_struct->address.sa)) {
-                                                               memcpy(&parsed_parameters->local_addr, &address_struct->address, sizeof(address_struct->address));
-                                                               if (!necp_address_is_wildcard(&parsed_parameters->local_addr)) {
-                                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR;
-                                                               }
-                                                               if ((parsed_parameters->local_addr.sa.sa_family == AF_INET && parsed_parameters->local_addr.sin.sin_port) ||
-                                                                       (parsed_parameters->local_addr.sa.sa_family == AF_INET6 && parsed_parameters->local_addr.sin6.sin6_port)) {
-                                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT;
-                                                               }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_LOCAL_ADDRESS: {
+                                       if (length >= sizeof(struct necp_policy_condition_addr)) {
+                                               struct necp_policy_condition_addr *address_struct = (struct necp_policy_condition_addr *)(void *)value;
+                                               if (necp_client_address_is_valid(&address_struct->address.sa)) {
+                                                       memcpy(&parsed_parameters->local_addr, &address_struct->address, sizeof(address_struct->address));
+                                                       if (!necp_address_is_wildcard(&parsed_parameters->local_addr)) {
+                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR;
                                                        }
-                                               }
-                                               break;
-                                       }
-                                       case NECP_CLIENT_PARAMETER_LOCAL_ENDPOINT: {
-                                               if (length >= sizeof(struct necp_client_endpoint)) {
-                                                       struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
-                                                       if (necp_client_address_is_valid(&endpoint->u.sa)) {
-                                                               memcpy(&parsed_parameters->local_addr, &endpoint->u.sa, sizeof(union necp_sockaddr_union));
-                                                               if (!necp_address_is_wildcard(&parsed_parameters->local_addr)) {
-                                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR;
-                                                               }
-                                                               if ((parsed_parameters->local_addr.sa.sa_family == AF_INET && parsed_parameters->local_addr.sin.sin_port) ||
-                                                                       (parsed_parameters->local_addr.sa.sa_family == AF_INET6 && parsed_parameters->local_addr.sin6.sin6_port)) {
-                                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT;
-                                                               }
+                                                       if ((parsed_parameters->local_addr.sa.sa_family == AF_INET && parsed_parameters->local_addr.sin.sin_port) ||
+                                                           (parsed_parameters->local_addr.sa.sa_family == AF_INET6 && parsed_parameters->local_addr.sin6.sin6_port)) {
+                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT;
                                                        }
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_REMOTE_ADDRESS: {
-                                               if (length >= sizeof(struct necp_policy_condition_addr)) {
-                                                       struct necp_policy_condition_addr *address_struct = (struct necp_policy_condition_addr *)(void *)value;
-                                                       if (necp_client_address_is_valid(&address_struct->address.sa)) {
-                                                               memcpy(&parsed_parameters->remote_addr, &address_struct->address, sizeof(address_struct->address));
-                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR;
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_LOCAL_ENDPOINT: {
+                                       if (length >= sizeof(struct necp_client_endpoint)) {
+                                               struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
+                                               if (necp_client_address_is_valid(&endpoint->u.sa)) {
+                                                       memcpy(&parsed_parameters->local_addr, &endpoint->u.sa, sizeof(union necp_sockaddr_union));
+                                                       if (!necp_address_is_wildcard(&parsed_parameters->local_addr)) {
+                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR;
                                                        }
-                                               }
-                                               break;
-                                       }
-                                       case NECP_CLIENT_PARAMETER_REMOTE_ENDPOINT: {
-                                               if (length >= sizeof(struct necp_client_endpoint)) {
-                                                       struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
-                                                       if (necp_client_address_is_valid(&endpoint->u.sa)) {
-                                                               memcpy(&parsed_parameters->remote_addr, &endpoint->u.sa, sizeof(union necp_sockaddr_union));
-                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR;
+                                                       if ((parsed_parameters->local_addr.sa.sa_family == AF_INET && parsed_parameters->local_addr.sin.sin_port) ||
+                                                           (parsed_parameters->local_addr.sa.sa_family == AF_INET6 && parsed_parameters->local_addr.sin6.sin6_port)) {
+                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_PORT;
                                                        }
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PROHIBIT_INTERFACE: {
-                                               if (num_prohibited_interfaces >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length <= IFXNAMSIZ && length > 0) {
-                                                       memcpy(parsed_parameters->prohibited_interfaces[num_prohibited_interfaces], value, length);
-                                                       parsed_parameters->prohibited_interfaces[num_prohibited_interfaces][length - 1] = 0; // Make sure the string is NULL terminated
-                                                       num_prohibited_interfaces++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF;
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_REMOTE_ADDRESS: {
+                                       if (length >= sizeof(struct necp_policy_condition_addr)) {
+                                               struct necp_policy_condition_addr *address_struct = (struct necp_policy_condition_addr *)(void *)value;
+                                               if (necp_client_address_is_valid(&address_struct->address.sa)) {
+                                                       memcpy(&parsed_parameters->remote_addr, &address_struct->address, sizeof(address_struct->address));
+                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR;
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_REQUIRE_IF_TYPE: {
-                                               if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(u_int8_t)) {
-                                                       memcpy(&parsed_parameters->required_interface_type, value, sizeof(u_int8_t));
-                                                       if (parsed_parameters->required_interface_type) {
-                                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE;
-                                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_REMOTE_ENDPOINT: {
+                                       if (length >= sizeof(struct necp_client_endpoint)) {
+                                               struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
+                                               if (necp_client_address_is_valid(&endpoint->u.sa)) {
+                                                       memcpy(&parsed_parameters->remote_addr, &endpoint->u.sa, sizeof(union necp_sockaddr_union));
+                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR;
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PROHIBIT_IF_TYPE: {
-                                               if (num_prohibited_interface_types >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(u_int8_t)) {
-                                                       memcpy(&parsed_parameters->prohibited_interface_types[num_prohibited_interface_types], value, sizeof(u_int8_t));
-                                                       num_prohibited_interface_types++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE;
-                                               }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PROHIBIT_INTERFACE: {
+                                       if (num_prohibited_interfaces >= NECP_MAX_INTERFACE_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_REQUIRE_AGENT: {
-                                               if (num_required_agents >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(uuid_t)) {
-                                                       memcpy(&parsed_parameters->required_netagents[num_required_agents], value, sizeof(uuid_t));
-                                                       num_required_agents++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT;
-                                               }
-                                               break;
+                                       if (length <= IFXNAMSIZ && length > 0) {
+                                               memcpy(parsed_parameters->prohibited_interfaces[num_prohibited_interfaces], value, length);
+                                               parsed_parameters->prohibited_interfaces[num_prohibited_interfaces][length - 1] = 0;         // Make sure the string is NULL terminated
+                                               num_prohibited_interfaces++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PROHIBIT_AGENT: {
-                                               if (num_prohibited_agents >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(uuid_t)) {
-                                                       memcpy(&parsed_parameters->prohibited_netagents[num_prohibited_agents], value, sizeof(uuid_t));
-                                                       num_prohibited_agents++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT;
-                                               }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_REQUIRE_IF_TYPE: {
+                                       if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PREFER_AGENT: {
-                                               if (num_preferred_agents >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(uuid_t)) {
-                                                       memcpy(&parsed_parameters->preferred_netagents[num_preferred_agents], value, sizeof(uuid_t));
-                                                       num_preferred_agents++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT;
+                                       if (length >= sizeof(u_int8_t)) {
+                                               memcpy(&parsed_parameters->required_interface_type, value, sizeof(u_int8_t));
+                                               if (parsed_parameters->required_interface_type) {
+                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE;
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_REQUIRE_AGENT_TYPE: {
-                                               if (num_required_agent_types >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
-                                                       memcpy(&parsed_parameters->required_netagent_types[num_required_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
-                                                       num_required_agent_types++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE;
-                                               }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PROHIBIT_IF_TYPE: {
+                                       if (num_prohibited_interface_types >= NECP_MAX_INTERFACE_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PROHIBIT_AGENT_TYPE: {
-                                               if (num_prohibited_agent_types >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
-                                                       memcpy(&parsed_parameters->prohibited_netagent_types[num_prohibited_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
-                                                       num_prohibited_agent_types++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE;
-                                               }
+                                       if (length >= sizeof(u_int8_t)) {
+                                               memcpy(&parsed_parameters->prohibited_interface_types[num_prohibited_interface_types], value, sizeof(u_int8_t));
+                                               num_prohibited_interface_types++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_REQUIRE_AGENT: {
+                                       if (num_required_agents >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PREFER_AGENT_TYPE: {
-                                               if (num_preferred_agent_types >= NECP_MAX_PARSED_PARAMETERS) {
-                                                       break;
-                                               }
-                                               if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
-                                                       memcpy(&parsed_parameters->preferred_netagent_types[num_preferred_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
-                                                       num_preferred_agent_types++;
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE;
-                                               }
+                                       if (length >= sizeof(uuid_t)) {
+                                               memcpy(&parsed_parameters->required_netagents[num_required_agents], value, sizeof(uuid_t));
+                                               num_required_agents++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PROHIBIT_AGENT: {
+                                       if (num_prohibited_agents >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_FLAGS: {
-                                               if (length >= sizeof(u_int32_t)) {
-                                                       memcpy(&parsed_parameters->flags, value, sizeof(parsed_parameters->flags));
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_FLAGS;
-                                               }
+                                       if (length >= sizeof(uuid_t)) {
+                                               memcpy(&parsed_parameters->prohibited_netagents[num_prohibited_agents], value, sizeof(uuid_t));
+                                               num_prohibited_agents++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PREFER_AGENT: {
+                                       if (num_preferred_agents >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_IP_PROTOCOL: {
-                                               if (length >= sizeof(parsed_parameters->ip_protocol)) {
-                                                       memcpy(&parsed_parameters->ip_protocol, value, sizeof(parsed_parameters->ip_protocol));
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_IP_PROTOCOL;
-                                               }
+                                       if (length >= sizeof(uuid_t)) {
+                                               memcpy(&parsed_parameters->preferred_netagents[num_preferred_agents], value, sizeof(uuid_t));
+                                               num_preferred_agents++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_AVOID_AGENT: {
+                                       if (num_avoided_agents >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_PID: {
-                                               if (length >= sizeof(parsed_parameters->effective_pid)) {
-                                                       memcpy(&parsed_parameters->effective_pid, value, sizeof(parsed_parameters->effective_pid));
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_PID;
-                                               }
+                                       if (length >= sizeof(uuid_t)) {
+                                               memcpy(&parsed_parameters->avoided_netagents[num_avoided_agents], value, sizeof(uuid_t));
+                                               num_avoided_agents++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_REQUIRE_AGENT_TYPE: {
+                                       if (num_required_agent_types >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_APPLICATION: {
-                                               if (length >= sizeof(parsed_parameters->effective_uuid)) {
-                                                       memcpy(&parsed_parameters->effective_uuid, value, sizeof(parsed_parameters->effective_uuid));
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_UUID;
-                                               }
+                                       if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
+                                               memcpy(&parsed_parameters->required_netagent_types[num_required_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
+                                               num_required_agent_types++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PROHIBIT_AGENT_TYPE: {
+                                       if (num_prohibited_agent_types >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       case NECP_CLIENT_PARAMETER_TRAFFIC_CLASS: {
-                                               if (length >= sizeof(parsed_parameters->traffic_class)) {
-                                                       memcpy(&parsed_parameters->traffic_class, value, sizeof(parsed_parameters->traffic_class));
-                                                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_TRAFFIC_CLASS;
-                                               }
+                                       if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
+                                               memcpy(&parsed_parameters->prohibited_netagent_types[num_prohibited_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
+                                               num_prohibited_agent_types++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PREFER_AGENT_TYPE: {
+                                       if (num_preferred_agent_types >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
-                                       default: {
+                                       if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
+                                               memcpy(&parsed_parameters->preferred_netagent_types[num_preferred_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
+                                               num_preferred_agent_types++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_AVOID_AGENT_TYPE: {
+                                       if (num_avoided_agent_types >= NECP_MAX_AGENT_PARAMETERS) {
                                                break;
                                        }
+                                       if (length >= sizeof(struct necp_client_parameter_netagent_type)) {
+                                               memcpy(&parsed_parameters->avoided_netagent_types[num_avoided_agent_types], value, sizeof(struct necp_client_parameter_netagent_type));
+                                               num_avoided_agent_types++;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT_TYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_FLAGS: {
+                                       if (length >= sizeof(u_int32_t)) {
+                                               memcpy(&parsed_parameters->flags, value, sizeof(parsed_parameters->flags));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_FLAGS;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_IP_PROTOCOL: {
+                                       if (length == sizeof(u_int16_t)) {
+                                               u_int16_t large_ip_protocol = 0;
+                                               memcpy(&large_ip_protocol, value, sizeof(large_ip_protocol));
+                                               parsed_parameters->ip_protocol = (u_int8_t)large_ip_protocol;
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_IP_PROTOCOL;
+                                       } else if (length >= sizeof(parsed_parameters->ip_protocol)) {
+                                               memcpy(&parsed_parameters->ip_protocol, value, sizeof(parsed_parameters->ip_protocol));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_IP_PROTOCOL;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_TRANSPORT_PROTOCOL: {
+                                       if (length >= sizeof(parsed_parameters->transport_protocol)) {
+                                               memcpy(&parsed_parameters->transport_protocol, value, sizeof(parsed_parameters->transport_protocol));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_TRANSPORT_PROTOCOL;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PID: {
+                                       if (length >= sizeof(parsed_parameters->effective_pid)) {
+                                               memcpy(&parsed_parameters->effective_pid, value, sizeof(parsed_parameters->effective_pid));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_PID;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_DELEGATED_UPID: {
+                                       if (length >= sizeof(parsed_parameters->delegated_upid)) {
+                                               memcpy(&parsed_parameters->delegated_upid, value, sizeof(parsed_parameters->delegated_upid));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_DELEGATED_UPID;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_ETHERTYPE: {
+                                       if (length >= sizeof(parsed_parameters->ethertype)) {
+                                               memcpy(&parsed_parameters->ethertype, value, sizeof(parsed_parameters->ethertype));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_ETHERTYPE;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_APPLICATION: {
+                                       if (length >= sizeof(parsed_parameters->effective_uuid)) {
+                                               memcpy(&parsed_parameters->effective_uuid, value, sizeof(parsed_parameters->effective_uuid));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_EFFECTIVE_UUID;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_TRAFFIC_CLASS: {
+                                       if (length >= sizeof(parsed_parameters->traffic_class)) {
+                                               memcpy(&parsed_parameters->traffic_class, value, sizeof(parsed_parameters->traffic_class));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_TRAFFIC_CLASS;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_RESOLVER_TAG: {
+                                       if (length > 0) {
+                                               resolver_tag = (u_int8_t *)value;
+                                               resolver_tag_length = length;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_DOMAIN: {
+                                       if (length > 0) {
+                                               client_hostname = (u_int8_t *)value;
+                                               hostname_length = length;
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_PARENT_ID: {
+                                       if (length == sizeof(parent_id)) {
+                                               uuid_copy(parent_id, value);
+                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_PARAMETER_LOCAL_ADDRESS_PREFERENCE: {
+                                       if (length >= sizeof(parsed_parameters->local_address_preference)) {
+                                               memcpy(&parsed_parameters->local_address_preference, value, sizeof(parsed_parameters->local_address_preference));
+                                               parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR_PREFERENCE;
+                                       }
+                                       break;
+                               }
+                               default: {
+                                       break;
+                               }
                                }
                        }
                }
@@ -1597,15 +2169,31 @@ necp_client_parse_parameters(u_int8_t *parameters,
                offset += sizeof(struct necp_tlv_header) + length;
        }
 
-       return (error);
+       if (resolver_tag != NULL) {
+               union necp_sockaddr_union remote_addr;
+               memcpy(&remote_addr, &parsed_parameters->remote_addr, sizeof(remote_addr));
+               remote_addr.sin.sin_port = 0;
+               const bool validated = necp_validate_resolver_answer(parent_id,
+                   client_hostname, hostname_length,
+                   (u_int8_t *)&remote_addr, sizeof(remote_addr),
+                   resolver_tag, resolver_tag_length);
+               if (!validated) {
+                       error = EAUTH;
+                       NECPLOG(LOG_ERR, "Failed to validate answer for hostname %s", client_hostname);
+               }
+       }
+
+       return error;
 }
 
 static int
 necp_client_parse_result(u_int8_t *result,
-                                                u_int32_t result_size,
-                                                union necp_sockaddr_union *local_address,
-                                                union necp_sockaddr_union *remote_address)
+    u_int32_t result_size,
+    union necp_sockaddr_union *local_address,
+    union necp_sockaddr_union *remote_address,
+    void **flow_stats)
 {
+#pragma unused(flow_stats)
        int error = 0;
        size_t offset = 0;
 
@@ -1617,27 +2205,27 @@ necp_client_parse_result(u_int8_t *result,
                        u_int8_t *value = necp_buffer_get_tlv_value(result, offset, NULL);
                        if (value != NULL) {
                                switch (type) {
-                                       case NECP_CLIENT_RESULT_LOCAL_ENDPOINT: {
-                                               if (length >= sizeof(struct necp_client_endpoint)) {
-                                                       struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
-                                                       if (local_address != NULL && necp_client_address_is_valid(&endpoint->u.sa)) {
-                                                               memcpy(local_address, &endpoint->u.sa, endpoint->u.sa.sa_len);
-                                                       }
+                               case NECP_CLIENT_RESULT_LOCAL_ENDPOINT: {
+                                       if (length >= sizeof(struct necp_client_endpoint)) {
+                                               struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
+                                               if (local_address != NULL && necp_client_address_is_valid(&endpoint->u.sa)) {
+                                                       memcpy(local_address, &endpoint->u.sa, endpoint->u.sa.sa_len);
                                                }
-                                               break;
                                        }
-                                       case NECP_CLIENT_RESULT_REMOTE_ENDPOINT: {
-                                               if (length >= sizeof(struct necp_client_endpoint)) {
-                                                       struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
-                                                       if (remote_address != NULL && necp_client_address_is_valid(&endpoint->u.sa)) {
-                                                               memcpy(remote_address, &endpoint->u.sa, endpoint->u.sa.sa_len);
-                                                       }
+                                       break;
+                               }
+                               case NECP_CLIENT_RESULT_REMOTE_ENDPOINT: {
+                                       if (length >= sizeof(struct necp_client_endpoint)) {
+                                               struct necp_client_endpoint *endpoint = (struct necp_client_endpoint *)(void *)value;
+                                               if (remote_address != NULL && necp_client_address_is_valid(&endpoint->u.sa)) {
+                                                       memcpy(remote_address, &endpoint->u.sa, endpoint->u.sa.sa_len);
                                                }
-                                               break;
-                                       }
-                                       default: {
-                                               break;
                                        }
+                                       break;
+                               }
+                               default: {
+                                       break;
+                               }
                                }
                        }
                }
@@ -1645,40 +2233,117 @@ necp_client_parse_result(u_int8_t *result,
                offset += sizeof(struct necp_tlv_header) + length;
        }
 
-       return (error);
+       return error;
 }
 
-int
-necp_client_register_socket_flow(pid_t pid, uuid_t client_id, struct inpcb *inp)
+static struct necp_client_flow_registration *
+necp_client_create_flow_registration(struct necp_fd_data *fd_data, struct necp_client *client)
+{
+       NECP_FD_ASSERT_LOCKED(fd_data);
+       NECP_CLIENT_ASSERT_LOCKED(client);
+
+       struct necp_client_flow_registration *new_registration = mcache_alloc(necp_flow_registration_cache, MCR_SLEEP);
+       if (new_registration == NULL) {
+               return NULL;
+       }
+
+       memset(new_registration, 0, sizeof(*new_registration));
+
+       new_registration->last_interface_details = combine_interface_details(IFSCOPE_NONE, NSTAT_IFNET_IS_UNKNOWN_TYPE);
+
+       necp_generate_client_id(new_registration->registration_id, true);
+       LIST_INIT(&new_registration->flow_list);
+
+       // Add registration to client list
+       RB_INSERT(_necp_client_flow_tree, &client->flow_registrations, new_registration);
+
+       // Add registration to fd list
+       RB_INSERT(_necp_fd_flow_tree, &fd_data->flows, new_registration);
+
+       // Add registration to global tree for lookup
+       NECP_FLOW_TREE_LOCK_EXCLUSIVE();
+       RB_INSERT(_necp_client_flow_global_tree, &necp_client_flow_global_tree, new_registration);
+       NECP_FLOW_TREE_UNLOCK();
+
+       new_registration->client = client;
+
+       // Start out assuming there is nothing to read from the flow
+       new_registration->flow_result_read = true;
+
+       return new_registration;
+}
+
+static void
+necp_client_add_socket_flow(struct necp_client_flow_registration *flow_registration,
+    struct inpcb *inp)
+{
+       struct necp_client_flow *new_flow = mcache_alloc(necp_flow_cache, MCR_SLEEP);
+       if (new_flow == NULL) {
+               NECPLOG0(LOG_ERR, "Failed to allocate socket flow");
+               return;
+       }
+
+       memset(new_flow, 0, sizeof(*new_flow));
+
+       new_flow->socket = TRUE;
+       new_flow->u.socket_handle = inp;
+       new_flow->u.cb = inp->necp_cb;
+
+       OSIncrementAtomic(&necp_socket_flow_count);
+
+       LIST_INSERT_HEAD(&flow_registration->flow_list, new_flow, flow_chain);
+}
+
+static int
+necp_client_register_socket_inner(pid_t pid, uuid_t client_id, struct inpcb *inp, bool is_listener)
 {
        int error = 0;
+       struct necp_fd_data *client_fd = NULL;
        bool found_client = FALSE;
 
-       NECP_CLIENT_TREE_LOCK_SHARED();
-
-       struct necp_client find;
-       uuid_copy(find.client_id, client_id);
-       struct necp_client *client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
-       if (client != NULL) {
-               NECP_CLIENT_LOCK(client);
+       NECP_FD_LIST_LOCK_SHARED();
+       LIST_FOREACH(client_fd, &necp_fd_list, chain) {
+               NECP_FD_LOCK(client_fd);
+               struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
+               if (client != NULL) {
+                       if (!pid || client->proc_pid == pid) {
+                               if (is_listener) {
+                                       found_client = TRUE;
+                               } else {
+                                       // Find client flow and assign from socket
+                                       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                                       if (flow_registration != NULL) {
+                                               // Found the right client and flow registration, add a new flow
+                                               found_client = TRUE;
+                                               necp_client_add_socket_flow(flow_registration, inp);
+                                       } else if (RB_EMPTY(&client->flow_registrations) && !necp_client_id_is_flow(client_id)) {
+                                               // No flows yet on this client, add a new registration
+                                               flow_registration = necp_client_create_flow_registration(client_fd, client);
+                                               if (flow_registration == NULL) {
+                                                       error = ENOMEM;
+                                               } else {
+                                                       // Add a new flow
+                                                       found_client = TRUE;
+                                                       necp_client_add_socket_flow(flow_registration, inp);
+                                               }
+                                       }
+                               }
+                       }
 
-               if (!pid || client->proc_pid == pid) {
-                       // Found the right client!
-                       found_client = TRUE;
-                       necp_client_add_socket_flow(client, inp);
+                       NECP_CLIENT_UNLOCK(client);
                }
+               NECP_FD_UNLOCK(client_fd);
 
-               NECP_CLIENT_UNLOCK(client);
+               if (found_client) {
+                       break;
+               }
        }
-
-       NECP_CLIENT_TREE_UNLOCK();
+       NECP_FD_LIST_UNLOCK();
 
        if (!found_client) {
                error = ENOENT;
        } else {
-               /*
-                * Count the sockets that have the NECP client UUID set
-                */
+               // Count the sockets that have the NECP client UUID set
                struct socket *so = inp->inp_socket;
                if (!(so->so_flags1 & SOF1_HAS_NECP_CLIENT_UUID)) {
                        so->so_flags1 |= SOF1_HAS_NECP_CLIENT_UUID;
@@ -1686,66 +2351,209 @@ necp_client_register_socket_flow(pid_t pid, uuid_t client_id, struct inpcb *inp)
                }
        }
 
-       return (error);
+       return error;
+}
+
+int
+necp_client_register_socket_flow(pid_t pid, uuid_t client_id, struct inpcb *inp)
+{
+       return necp_client_register_socket_inner(pid, client_id, inp, false);
+}
+
+int
+necp_client_register_socket_listener(pid_t pid, uuid_t client_id, struct inpcb *inp)
+{
+       return necp_client_register_socket_inner(pid, client_id, inp, true);
 }
 
+
 static void
-necp_client_add_multipath_cb(struct necp_client *client, struct mppcb *mpp)
+necp_client_add_multipath_interface_flows(struct necp_client_flow_registration *flow_registration,
+    struct necp_client *client,
+    struct mppcb *mpp)
 {
-       struct necp_client_flow *flow = NULL;
+       flow_registration->interface_handle = mpp;
+       flow_registration->interface_cb = mpp->necp_cb;
+
+       proc_t proc = proc_find(client->proc_pid);
+       if (proc == PROC_NULL) {
+               return;
+       }
+
+       // Traverse all interfaces and add a tracking flow if needed
+       necp_flow_add_interface_flows(proc, client, flow_registration, true);
+
+       proc_rele(proc);
+       proc = PROC_NULL;
+}
+
+int
+necp_client_register_multipath_cb(pid_t pid, uuid_t client_id, struct mppcb *mpp)
+{
+       int error = 0;
+       struct necp_fd_data *client_fd = NULL;
+       bool found_client = FALSE;
+
+       NECP_FD_LIST_LOCK_SHARED();
+       LIST_FOREACH(client_fd, &necp_fd_list, chain) {
+               NECP_FD_LOCK(client_fd);
+               struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
+               if (client != NULL) {
+                       if (!pid || client->proc_pid == pid) {
+                               struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                               if (flow_registration != NULL) {
+                                       // Found the right client and flow registration, add a new flow
+                                       found_client = TRUE;
+                                       necp_client_add_multipath_interface_flows(flow_registration, client, mpp);
+                               } else if (RB_EMPTY(&client->flow_registrations) && !necp_client_id_is_flow(client_id)) {
+                                       // No flows yet on this client, add a new registration
+                                       flow_registration = necp_client_create_flow_registration(client_fd, client);
+                                       if (flow_registration == NULL) {
+                                               error = ENOMEM;
+                                       } else {
+                                               // Add a new flow
+                                               found_client = TRUE;
+                                               necp_client_add_multipath_interface_flows(flow_registration, client, mpp);
+                                       }
+                               }
+                       }
+
+                       NECP_CLIENT_UNLOCK(client);
+               }
+               NECP_FD_UNLOCK(client_fd);
+
+               if (found_client) {
+                       break;
+               }
+       }
+       NECP_FD_LIST_UNLOCK();
+
+       if (!found_client && error == 0) {
+               error = ENOENT;
+       }
+
+       return error;
+}
+
+#define NETAGENT_DOMAIN_RADIO_MANAGER   "WirelessRadioManager"
+#define NETAGENT_TYPE_RADIO_MANAGER     "WirelessRadioManager:BB Manager"
+
+static int
+necp_client_lookup_bb_radio_manager(struct necp_client *client,
+    uuid_t netagent_uuid)
+{
+       char netagent_domain[NETAGENT_DOMAINSIZE];
+       char netagent_type[NETAGENT_TYPESIZE];
+       struct necp_aggregate_result result;
+       proc_t proc;
+       int error;
+
+       proc = proc_find(client->proc_pid);
+       if (proc == PROC_NULL) {
+               return ESRCH;
+       }
+
+       error = necp_application_find_policy_match_internal(proc, client->parameters, (u_int32_t)client->parameters_length,
+           &result, NULL, NULL, 0, NULL, NULL, NULL, NULL, NULL, true, true, NULL);
+
+       proc_rele(proc);
+       proc = PROC_NULL;
+
+       if (error) {
+               return error;
+       }
+
+       for (int i = 0; i < NECP_MAX_NETAGENTS; i++) {
+               if (uuid_is_null(result.netagents[i])) {
+                       // Passed end of valid agents
+                       break;
+               }
+
+               memset(&netagent_domain, 0, NETAGENT_DOMAINSIZE);
+               memset(&netagent_type, 0, NETAGENT_TYPESIZE);
+               if (netagent_get_agent_domain_and_type(result.netagents[i], netagent_domain, netagent_type) == FALSE) {
+                       continue;
+               }
 
-       client->interface_handle = mpp;
-       client->interface_cb = mpp->necp_cb;
+               if (strncmp(netagent_domain, NETAGENT_DOMAIN_RADIO_MANAGER, NETAGENT_DOMAINSIZE) != 0) {
+                       continue;
+               }
 
-       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-               if (flow->nexus || flow->socket) {
+               if (strncmp(netagent_type, NETAGENT_TYPE_RADIO_MANAGER, NETAGENT_TYPESIZE) != 0) {
                        continue;
                }
 
-               flow->u.socket_handle = mpp;
-               flow->u.cb = mpp->necp_cb;
+               uuid_copy(netagent_uuid, result.netagents[i]);
+
+               break;
+       }
+
+       return 0;
+}
+
+static int
+necp_client_assert_bb_radio_manager_common(struct necp_client *client, bool assert)
+{
+       uuid_t netagent_uuid;
+       uint8_t assert_type;
+       int error;
+
+       error = necp_client_lookup_bb_radio_manager(client, netagent_uuid);
+       if (error) {
+               NECPLOG0(LOG_ERR, "BB radio manager agent not found");
+               return error;
+       }
 
-               if (flow->viable && flow->u.cb) {
-                       flow->u.cb(mpp, NECP_CLIENT_CBACTION_INITIAL, flow);
+       // Before unasserting, verify that the assertion was already taken
+       if (assert == FALSE) {
+               assert_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
+
+               if (!necp_client_remove_assertion(client, netagent_uuid)) {
+                       return EINVAL;
                }
+       } else {
+               assert_type = NETAGENT_MESSAGE_TYPE_CLIENT_ASSERT;
        }
+
+       error = netagent_client_message(netagent_uuid, client->client_id, client->proc_pid, client->agent_handle, assert_type);
+       if (error) {
+               NECPLOG0(LOG_ERR, "netagent_client_message failed");
+               return error;
+       }
+
+       // Only save the assertion if the action succeeded
+       if (assert == TRUE) {
+               necp_client_add_assertion(client, netagent_uuid);
+       }
+
+       return 0;
 }
 
 int
-necp_client_register_multipath_cb(pid_t pid, uuid_t client_id, struct mppcb *mpp)
+necp_client_assert_bb_radio_manager(uuid_t client_id, bool assert)
 {
+       struct necp_client *client;
        int error = 0;
-       bool found_client = FALSE;
 
        NECP_CLIENT_TREE_LOCK_SHARED();
 
-       struct necp_client find;
-       uuid_copy(find.client_id, client_id);
-       struct necp_client *client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
-       if (client != NULL) {
-               NECP_CLIENT_LOCK(client);
+       client = necp_find_client_and_lock(client_id);
 
-               if (!pid || client->proc_pid == pid) {
-                       // Found the right client!
-                       found_client = TRUE;
-                       necp_client_add_multipath_cb(client, mpp);
-               }
+       if (client) {
+               // Found the right client!
+               error = necp_client_assert_bb_radio_manager_common(client, assert);
 
                NECP_CLIENT_UNLOCK(client);
+       } else {
+               NECPLOG0(LOG_ERR, "Couldn't find client");
+               error = ENOENT;
        }
 
        NECP_CLIENT_TREE_UNLOCK();
 
-       if (!found_client) {
-               error = ENOENT;
-       }
-
-       return (error);
+       return error;
 }
 
-#define        NETAGENT_DOMAIN_NETEXT  "NetworkExtension"
-#define        NETAGENT_TYPE_PATHCTRL  "PathController"
-
 static int
 necp_client_unregister_socket_flow(uuid_t client_id, void *handle)
 {
@@ -1760,22 +2568,26 @@ necp_client_unregister_socket_flow(uuid_t client_id, void *handle)
 
                struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
                if (client != NULL) {
-                       // Found the right client!
-                       found_client = TRUE;
+                       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                       if (flow_registration != NULL) {
+                               // Found the right client and flow!
+                               found_client = TRUE;
 
-                       // Remove flow assignment
-                       struct necp_client_flow *search_flow = NULL;
-                       struct necp_client_flow *temp_flow = NULL;
-                       LIST_FOREACH_SAFE(search_flow, &client->flow_list, flow_chain, temp_flow) {
-                               if (search_flow->socket && search_flow->u.socket_handle == handle) {
-                                       if (search_flow->assigned_results != NULL) {
-                                               FREE(search_flow->assigned_results, M_NETAGENT);
-                                               search_flow->assigned_results = NULL;
+                               // Remove flow assignment
+                               struct necp_client_flow *search_flow = NULL;
+                               struct necp_client_flow *temp_flow = NULL;
+                               LIST_FOREACH_SAFE(search_flow, &flow_registration->flow_list, flow_chain, temp_flow) {
+                                       if (search_flow->socket && search_flow->u.socket_handle == handle) {
+                                               if (search_flow->assigned_results != NULL) {
+                                                       FREE(search_flow->assigned_results, M_NETAGENT);
+                                                       search_flow->assigned_results = NULL;
+                                               }
+                                               client_updated = TRUE;
+                                               flow_registration->flow_result_read = FALSE;
+                                               LIST_REMOVE(search_flow, flow_chain);
+                                               OSDecrementAtomic(&necp_socket_flow_count);
+                                               mcache_free(necp_flow_cache, search_flow);
                                        }
-                                       client_updated = TRUE;
-                                       LIST_REMOVE(search_flow, flow_chain);
-                                       OSDecrementAtomic(&necp_socket_flow_count);
-                                       zfree(necp_flow_zone, search_flow);
                                }
                        }
 
@@ -1783,7 +2595,6 @@ necp_client_unregister_socket_flow(uuid_t client_id, void *handle)
                }
 
                if (client_updated) {
-                       client->flow_result_read = FALSE;
                        necp_fd_notify(client_fd, true);
                }
                NECP_FD_UNLOCK(client_fd);
@@ -1798,7 +2609,7 @@ necp_client_unregister_socket_flow(uuid_t client_id, void *handle)
                error = ENOENT;
        }
 
-       return (error);
+       return error;
 }
 
 static int
@@ -1809,28 +2620,27 @@ necp_client_unregister_multipath_cb(uuid_t client_id, void *handle)
 
        NECP_CLIENT_TREE_LOCK_SHARED();
 
-       struct necp_client find;
-       uuid_copy(find.client_id, client_id);
-       struct necp_client *client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
+       struct necp_client *client = necp_find_client_and_lock(client_id);
        if (client != NULL) {
-               NECP_CLIENT_LOCK(client);
-
-               // Found the right client!
-               found_client = TRUE;
+               struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+               if (flow_registration != NULL) {
+                       // Found the right client and flow!
+                       found_client = TRUE;
 
-               // Remove flow assignment
-               struct necp_client_flow *search_flow = NULL;
-               struct necp_client_flow *temp_flow = NULL;
-               LIST_FOREACH_SAFE(search_flow, &client->flow_list, flow_chain, temp_flow) {
-                       if (!search_flow->socket && !search_flow->nexus &&
-                               search_flow->u.socket_handle == handle) {
-                               search_flow->u.socket_handle = NULL;
-                               search_flow->u.cb = NULL;
+                       // Remove flow assignment
+                       struct necp_client_flow *search_flow = NULL;
+                       struct necp_client_flow *temp_flow = NULL;
+                       LIST_FOREACH_SAFE(search_flow, &flow_registration->flow_list, flow_chain, temp_flow) {
+                               if (!search_flow->socket && !search_flow->nexus &&
+                                   search_flow->u.socket_handle == handle) {
+                                       search_flow->u.socket_handle = NULL;
+                                       search_flow->u.cb = NULL;
+                               }
                        }
-               }
 
-               client->interface_handle = NULL;
-               client->interface_cb = NULL;
+                       flow_registration->interface_handle = NULL;
+                       flow_registration->interface_cb = NULL;
+               }
 
                NECP_CLIENT_UNLOCK(client);
        }
@@ -1841,7 +2651,7 @@ necp_client_unregister_multipath_cb(uuid_t client_id, void *handle)
                error = ENOENT;
        }
 
-       return (error);
+       return error;
 }
 
 int
@@ -1867,58 +2677,68 @@ necp_client_assign_from_socket(pid_t pid, uuid_t client_id, struct inpcb *inp)
 
                struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
                if (client != NULL) {
-                       // Found the right client!
-                       found_client = TRUE;
-
-                       struct necp_client_flow *flow = NULL;
-                       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-                               if (flow->socket && flow->u.socket_handle == inp) {
-                                       // Release prior results and route
-                                       if (flow->assigned_results != NULL) {
-                                               FREE(flow->assigned_results, M_NETAGENT);
-                                               flow->assigned_results = NULL;
-                                       }
+                       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                       if (flow_registration == NULL && RB_EMPTY(&client->flow_registrations) && !necp_client_id_is_flow(client_id)) {
+                               // No flows yet on this client, add a new registration
+                               flow_registration = necp_client_create_flow_registration(client_fd, client);
+                               if (flow_registration == NULL) {
+                                       error = ENOMEM;
+                               }
+                       }
+                       if (flow_registration != NULL) {
+                               // Found the right client and flow!
+                               found_client = TRUE;
 
-                                       ifnet_t ifp = NULL;
-                                       if ((inp->inp_flags & INP_BOUND_IF) && inp->inp_boundifp) {
-                                               ifp = inp->inp_boundifp;
-                                       } else {
-                                               ifp = inp->inp_last_outifp;
-                                       }
+                               struct necp_client_flow *flow = NULL;
+                               LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
+                                       if (flow->socket && flow->u.socket_handle == inp) {
+                                               // Release prior results and route
+                                               if (flow->assigned_results != NULL) {
+                                                       FREE(flow->assigned_results, M_NETAGENT);
+                                                       flow->assigned_results = NULL;
+                                               }
 
-                                       if (ifp != NULL) {
-                                               flow->interface_index = ifp->if_index;
-                                       } else {
-                                               flow->interface_index = IFSCOPE_NONE;
-                                       }
+                                               ifnet_t ifp = NULL;
+                                               if ((inp->inp_flags & INP_BOUND_IF) && inp->inp_boundifp) {
+                                                       ifp = inp->inp_boundifp;
+                                               } else {
+                                                       ifp = inp->inp_last_outifp;
+                                               }
 
-                                       if (inp->inp_vflag & INP_IPV4) {
-                                               flow->local_addr.sin.sin_family = AF_INET;
-                                               flow->local_addr.sin.sin_len = sizeof(struct sockaddr_in);
-                                               flow->local_addr.sin.sin_port = inp->inp_lport;
-                                               memcpy(&flow->local_addr.sin.sin_addr, &inp->inp_laddr, sizeof(struct in_addr));
-
-                                               flow->remote_addr.sin.sin_family = AF_INET;
-                                               flow->remote_addr.sin.sin_len = sizeof(struct sockaddr_in);
-                                               flow->remote_addr.sin.sin_port = inp->inp_fport;
-                                               memcpy(&flow->remote_addr.sin.sin_addr, &inp->inp_faddr, sizeof(struct in_addr));
-                                       } else if (inp->inp_vflag & INP_IPV6) {
-                                               in6_ip6_to_sockaddr(&inp->in6p_laddr, inp->inp_lport, &flow->local_addr.sin6, sizeof(flow->local_addr));
-                                               in6_ip6_to_sockaddr(&inp->in6p_faddr, inp->inp_fport, &flow->remote_addr.sin6, sizeof(flow->remote_addr));
-                                       }
+                                               if (ifp != NULL) {
+                                                       flow->interface_index = ifp->if_index;
+                                               } else {
+                                                       flow->interface_index = IFSCOPE_NONE;
+                                               }
 
-                                       flow->viable = necp_client_flow_is_viable(proc, client, flow);
+                                               if (inp->inp_vflag & INP_IPV4) {
+                                                       flow->local_addr.sin.sin_family = AF_INET;
+                                                       flow->local_addr.sin.sin_len = sizeof(struct sockaddr_in);
+                                                       flow->local_addr.sin.sin_port = inp->inp_lport;
+                                                       memcpy(&flow->local_addr.sin.sin_addr, &inp->inp_laddr, sizeof(struct in_addr));
+
+                                                       flow->remote_addr.sin.sin_family = AF_INET;
+                                                       flow->remote_addr.sin.sin_len = sizeof(struct sockaddr_in);
+                                                       flow->remote_addr.sin.sin_port = inp->inp_fport;
+                                                       memcpy(&flow->remote_addr.sin.sin_addr, &inp->inp_faddr, sizeof(struct in_addr));
+                                               } else if (inp->inp_vflag & INP_IPV6) {
+                                                       in6_ip6_to_sockaddr(&inp->in6p_laddr, inp->inp_lport, &flow->local_addr.sin6, sizeof(flow->local_addr));
+                                                       in6_ip6_to_sockaddr(&inp->in6p_faddr, inp->inp_fport, &flow->remote_addr.sin6, sizeof(flow->remote_addr));
+                                               }
 
-                                       uuid_t empty_uuid;
-                                       uuid_clear(empty_uuid);
-                                       flow->assigned = TRUE;
-                                       flow->assigned_results = necp_create_nexus_assign_message(empty_uuid, 0, NULL, 0,
-                                                                                                                                                         (struct necp_client_endpoint *)&flow->local_addr,
-                                                                                                                                                         (struct necp_client_endpoint *)&flow->remote_addr,
-                                                                                                                                                         0, &flow->assigned_results_length);
-                                       client->flow_result_read = FALSE;
-                                       client_updated = TRUE;
-                                       break;
+                                               flow->viable = necp_client_flow_is_viable(proc, client, flow);
+
+                                               uuid_t empty_uuid;
+                                               uuid_clear(empty_uuid);
+                                               flow->assigned = TRUE;
+                                               flow->assigned_results = necp_create_nexus_assign_message(empty_uuid, 0, NULL, 0,
+                                                   (struct necp_client_endpoint *)&flow->local_addr,
+                                                   (struct necp_client_endpoint *)&flow->remote_addr,
+                                                   NULL, 0, NULL, &flow->assigned_results_length);
+                                               flow_registration->flow_result_read = FALSE;
+                                               client_updated = TRUE;
+                                               break;
+                                       }
                                }
                        }
 
@@ -1932,19 +2752,72 @@ necp_client_assign_from_socket(pid_t pid, uuid_t client_id, struct inpcb *inp)
                proc_rele(proc);
                proc = PROC_NULL;
 
-               if (found_client) {
-                       break;
+               if (found_client) {
+                       break;
+               }
+       }
+       NECP_FD_LIST_UNLOCK();
+
+       if (error == 0) {
+               if (!found_client) {
+                       error = ENOENT;
+               } else if (!client_updated) {
+                       error = EINVAL;
+               }
+       }
+
+       return error;
+}
+
+bool
+necp_socket_is_allowed_to_recv_on_interface(struct inpcb *inp, ifnet_t interface)
+{
+       if (interface == NULL ||
+           inp == NULL ||
+           !(inp->inp_flags2 & INP2_EXTERNAL_PORT) ||
+           uuid_is_null(inp->necp_client_uuid)) {
+               // If there's no interface or client ID to check,
+               // or if this is not a listener, pass.
+               // Outbound connections will have already been
+               // validated for policy.
+               return TRUE;
+       }
+
+       // Only filter out listener sockets (no remote address specified)
+       if ((inp->inp_vflag & INP_IPV4) &&
+           inp->inp_faddr.s_addr != INADDR_ANY) {
+               return TRUE;
+       }
+       if ((inp->inp_vflag & INP_IPV6) &&
+           !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
+               return TRUE;
+       }
+
+       bool allowed = TRUE;
+
+       NECP_CLIENT_TREE_LOCK_SHARED();
+
+       struct necp_client *client = necp_find_client_and_lock(inp->necp_client_uuid);
+       if (client != NULL) {
+               struct necp_client_parsed_parameters *parsed_parameters = NULL;
+
+               MALLOC(parsed_parameters, struct necp_client_parsed_parameters *, sizeof(*parsed_parameters), M_NECP, (M_WAITOK | M_ZERO));
+               if (parsed_parameters != NULL) {
+                       int error = necp_client_parse_parameters(client->parameters, (u_int32_t)client->parameters_length, parsed_parameters);
+                       if (error == 0) {
+                               if (!necp_ifnet_matches_parameters(interface, parsed_parameters, 0, NULL, true, false)) {
+                                       allowed = FALSE;
+                               }
+                       }
+                       FREE(parsed_parameters, M_NECP);
                }
-       }
-       NECP_FD_LIST_UNLOCK();
 
-       if (!found_client) {
-               error = ENOENT;
-       } else if (!client_updated) {
-               error = EINVAL;
+               NECP_CLIENT_UNLOCK(client);
        }
 
-       return (error);
+       NECP_CLIENT_TREE_UNLOCK();
+
+       return allowed;
 }
 
 int
@@ -1968,22 +2841,25 @@ necp_update_flow_protoctl_event(uuid_t netagent_uuid, uuid_t client_id,
 
                struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
                if (client != NULL) {
-                       /* Found the right client! */
-                       found_client = TRUE;
+                       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                       if (flow_registration != NULL) {
+                               // Found the right client and flow!
+                               found_client = TRUE;
 
-                       struct necp_client_flow *flow = NULL;
-                       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-                               // Verify that the client nexus agent matches
-                               if (flow->nexus &&
-                                   uuid_compare(flow->u.nexus_agent,
-                                   netagent_uuid) == 0) {
-                                       flow->has_protoctl_event = TRUE;
-                                       flow->protoctl_event.protoctl_event_code = protoctl_event_code;
-                                       flow->protoctl_event.protoctl_event_val = protoctl_event_val;
-                                       flow->protoctl_event.protoctl_event_tcp_seq_num = protoctl_event_tcp_seq_number;
-                                       client->flow_result_read = FALSE;
-                                       client_updated = TRUE;
-                                       break;
+                               struct necp_client_flow *flow = NULL;
+                               LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
+                                       // Verify that the client nexus agent matches
+                                       if (flow->nexus &&
+                                           uuid_compare(flow->u.nexus_agent,
+                                           netagent_uuid) == 0) {
+                                               flow->has_protoctl_event = TRUE;
+                                               flow->protoctl_event.protoctl_event_code = protoctl_event_code;
+                                               flow->protoctl_event.protoctl_event_val = protoctl_event_val;
+                                               flow->protoctl_event.protoctl_event_tcp_seq_num = protoctl_event_tcp_seq_number;
+                                               flow_registration->flow_result_read = FALSE;
+                                               client_updated = TRUE;
+                                               break;
+                                       }
                                }
                        }
 
@@ -2009,11 +2885,18 @@ necp_update_flow_protoctl_event(uuid_t netagent_uuid, uuid_t client_id,
        } else if (!client_updated) {
                error = EINVAL;
        }
-       return (error);
+       return error;
 }
 
 static bool
-necp_assign_client_result_locked(struct proc *proc, struct necp_fd_data *client_fd, struct necp_client *client, uuid_t netagent_uuid, u_int8_t *assigned_results, size_t assigned_results_length)
+necp_assign_client_result_locked(struct proc *proc,
+    struct necp_fd_data *client_fd,
+    struct necp_client *client,
+    struct necp_client_flow_registration *flow_registration,
+    uuid_t netagent_uuid,
+    u_int8_t *assigned_results,
+    size_t assigned_results_length,
+    bool notify_fd)
 {
        bool client_updated = FALSE;
 
@@ -2021,19 +2904,20 @@ necp_assign_client_result_locked(struct proc *proc, struct necp_fd_data *client_
        NECP_CLIENT_ASSERT_LOCKED(client);
 
        struct necp_client_flow *flow = NULL;
-       LIST_FOREACH(flow, &client->flow_list, flow_chain) {
+       LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
                // Verify that the client nexus agent matches
                if (flow->nexus &&
-                       uuid_compare(flow->u.nexus_agent, netagent_uuid) == 0) {
+                   uuid_compare(flow->u.nexus_agent, netagent_uuid) == 0) {
                        // Release prior results and route
                        if (flow->assigned_results != NULL) {
                                FREE(flow->assigned_results, M_NETAGENT);
                                flow->assigned_results = NULL;
                        }
 
+                       void *nexus_stats = NULL;
                        if (assigned_results != NULL && assigned_results_length > 0) {
                                int error = necp_client_parse_result(assigned_results, (u_int32_t)assigned_results_length,
-                                                                                                &flow->local_addr, &flow->remote_addr);
+                                   &flow->local_addr, &flow->remote_addr, &nexus_stats);
                                VERIFY(error == 0);
                        }
 
@@ -2042,23 +2926,23 @@ necp_assign_client_result_locked(struct proc *proc, struct necp_fd_data *client_
                        flow->assigned = TRUE;
                        flow->assigned_results = assigned_results;
                        flow->assigned_results_length = assigned_results_length;
-                       client->flow_result_read = FALSE;
+                       flow_registration->flow_result_read = FALSE;
                        client_updated = TRUE;
                        break;
                }
        }
 
-       if (client_updated) {
+       if (client_updated && notify_fd) {
                necp_fd_notify(client_fd, true);
        }
 
        // if not updated, client must free assigned_results
-       return (client_updated);
+       return client_updated;
 }
 
 int
 necp_assign_client_result(uuid_t netagent_uuid, uuid_t client_id,
-                                                 u_int8_t *assigned_results, size_t assigned_results_length)
+    u_int8_t *assigned_results, size_t assigned_results_length)
 {
        int error = 0;
        struct necp_fd_data *client_fd = NULL;
@@ -2076,11 +2960,14 @@ necp_assign_client_result(uuid_t netagent_uuid, uuid_t client_id,
                NECP_FD_LOCK(client_fd);
                struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
                if (client != NULL) {
-                       // Found the right client!
-                       found_client = TRUE;
-
-                       if (necp_assign_client_result_locked(proc, client_fd, client, netagent_uuid, assigned_results, assigned_results_length)) {
-                               client_updated = TRUE;
+                       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+                       if (flow_registration != NULL) {
+                               // Found the right client and flow!
+                               found_client = TRUE;
+                               if (necp_assign_client_result_locked(proc, client_fd, client, flow_registration, netagent_uuid,
+                                   assigned_results, assigned_results_length, true)) {
+                                       client_updated = TRUE;
+                               }
                        }
 
                        NECP_CLIENT_UNLOCK(client);
@@ -2104,60 +2991,216 @@ necp_assign_client_result(uuid_t netagent_uuid, uuid_t client_id,
                error = EINVAL;
        }
 
-       return (error);
+       return error;
 }
 
 /// Client updating
 
 static bool
-necp_update_client_result(proc_t proc,
-                                                 struct necp_fd_data *client_fd,
-                                                 struct necp_client *client,
-                                                 struct _necp_client_defunct_list *defunct_list)
+necp_update_parsed_parameters(struct necp_client_parsed_parameters *parsed_parameters,
+    struct necp_aggregate_result *result)
 {
-       struct necp_client_result_netagent netagent;
-       struct necp_aggregate_result result;
-       struct necp_client_parsed_parameters *parsed_parameters = NULL;
-       u_int32_t flags = 0;
-       struct rtentry *route = NULL;
+       if (parsed_parameters == NULL ||
+           result == NULL) {
+               return false;
+       }
 
-       NECP_CLIENT_ASSERT_LOCKED(client);
+       bool updated = false;
+       for (int i = 0; i < NECP_MAX_NETAGENTS; i++) {
+               if (uuid_is_null(result->netagents[i])) {
+                       // Passed end of valid agents
+                       break;
+               }
 
-       MALLOC(parsed_parameters, struct necp_client_parsed_parameters *, sizeof(*parsed_parameters), M_NECP, (M_WAITOK | M_ZERO));
-       if (parsed_parameters == NULL) {
-           NECPLOG0(LOG_ERR, "Failed to allocate parsed parameters");
-           return (FALSE);
-       }
+               if (!(result->netagent_use_flags[i] & NECP_AGENT_USE_FLAG_SCOPE)) {
+                       // Not a scoped agent, ignore
+                       continue;
+               }
 
-       // Nexus flows will be brought back if they are still valid
-       necp_client_mark_all_nonsocket_flows_as_invalid(client);
+               // This is a scoped agent. Add it to the required agents.
+               if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT) {
+                       // Already some required agents, add this at the end
+                       for (int j = 0; j < NECP_MAX_AGENT_PARAMETERS; j++) {
+                               if (uuid_compare(parsed_parameters->required_netagents[j], result->netagents[i]) == 0) {
+                                       // Already required, break
+                                       break;
+                               }
+                               if (uuid_is_null(parsed_parameters->required_netagents[j])) {
+                                       // Add here
+                                       memcpy(&parsed_parameters->required_netagents[j], result->netagents[i], sizeof(uuid_t));
+                                       updated = true;
+                                       break;
+                               }
+                       }
+               } else {
+                       // No required agents yet, add this one
+                       parsed_parameters->valid_fields |= NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT;
+                       memcpy(&parsed_parameters->required_netagents[0], result->netagents[i], sizeof(uuid_t));
+                       updated = true;
+               }
+
+               // Remove requirements for agents of the same type
+               if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE) {
+                       char remove_agent_domain[NETAGENT_DOMAINSIZE] = { 0 };
+                       char remove_agent_type[NETAGENT_TYPESIZE] = { 0 };
+                       if (netagent_get_agent_domain_and_type(result->netagents[i], remove_agent_domain, remove_agent_type)) {
+                               for (int j = 0; j < NECP_MAX_AGENT_PARAMETERS; j++) {
+                                       if (strlen(parsed_parameters->required_netagent_types[j].netagent_domain) == 0 &&
+                                           strlen(parsed_parameters->required_netagent_types[j].netagent_type) == 0) {
+                                               break;
+                                       }
 
-       int error = necp_client_parse_parameters(client->parameters, (u_int32_t)client->parameters_length, parsed_parameters);
-       if (error != 0) {
-               FREE(parsed_parameters, M_NECP);
-               return (FALSE);
+                                       if (strncmp(parsed_parameters->required_netagent_types[j].netagent_domain, remove_agent_domain, NETAGENT_DOMAINSIZE) == 0 &&
+                                           strncmp(parsed_parameters->required_netagent_types[j].netagent_type, remove_agent_type, NETAGENT_TYPESIZE) == 0) {
+                                               updated = true;
+
+                                               if (j == NECP_MAX_AGENT_PARAMETERS - 1) {
+                                                       // Last field, just clear and break
+                                                       memset(&parsed_parameters->required_netagent_types[NECP_MAX_AGENT_PARAMETERS - 1], 0, sizeof(struct necp_client_parameter_netagent_type));
+                                                       break;
+                                               } else {
+                                                       // Move the parameters down, clear the last entry
+                                                       memmove(&parsed_parameters->required_netagent_types[j],
+                                                           &parsed_parameters->required_netagent_types[j + 1],
+                                                           sizeof(struct necp_client_parameter_netagent_type) * (NECP_MAX_AGENT_PARAMETERS - (j + 1)));
+                                                       memset(&parsed_parameters->required_netagent_types[NECP_MAX_AGENT_PARAMETERS - 1], 0, sizeof(struct necp_client_parameter_netagent_type));
+                                                       // Continue, don't increment but look at the new shifted item instead
+                                                       continue;
+                                               }
+                                       }
+
+                                       // Increment j to look at the next agent type parameter
+                                       j++;
+                               }
+                       }
+               }
        }
 
-       // Update saved IP protocol
-       client->ip_protocol = parsed_parameters->ip_protocol;
+       if (updated &&
+           parsed_parameters->required_interface_index != IFSCOPE_NONE &&
+           (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF) == 0) {
+               // A required interface index was added after the fact. Clear it.
+               parsed_parameters->required_interface_index = IFSCOPE_NONE;
+       }
+
+
+       return updated;
+}
+
+static inline bool
+necp_agent_types_match(const char *agent_domain1, const char *agent_type1,
+    const char *agent_domain2, const char *agent_type2)
+{
+       return (strlen(agent_domain1) == 0 ||
+              strncmp(agent_domain2, agent_domain1, NETAGENT_DOMAINSIZE) == 0) &&
+              (strlen(agent_type1) == 0 ||
+              strncmp(agent_type2, agent_type1, NETAGENT_TYPESIZE) == 0);
+}
+
+static inline bool
+necp_calculate_client_result(proc_t proc,
+    struct necp_client *client,
+    struct necp_client_parsed_parameters *parsed_parameters,
+    struct necp_aggregate_result *result,
+    u_int32_t *flags,
+    u_int32_t *reason,
+    struct necp_client_endpoint *v4_gateway,
+    struct necp_client_endpoint *v6_gateway,
+    uuid_t *override_euuid)
+{
+       struct rtentry *route = NULL;
 
        // Check parameters to find best interface
+       bool validate_agents = false;
        u_int matching_if_index = 0;
-       if (necp_find_matching_interface_index(parsed_parameters, &matching_if_index)) {
+       if (necp_find_matching_interface_index(parsed_parameters, &matching_if_index, &validate_agents)) {
                if (matching_if_index != 0) {
                        parsed_parameters->required_interface_index = matching_if_index;
                }
                // Interface found or not needed, match policy.
-               error = necp_application_find_policy_match_internal(proc, client->parameters,
-                                                                                                                       (u_int32_t)client->parameters_length,
-                                                                                                                       &result, &flags, matching_if_index,
-                                                                                                                       NULL, NULL, &route, false);
+               memset(result, 0, sizeof(*result));
+               int error = necp_application_find_policy_match_internal(proc, client->parameters,
+                   (u_int32_t)client->parameters_length,
+                   result, flags, reason, matching_if_index,
+                   NULL, NULL,
+                   v4_gateway, v6_gateway,
+                   &route, false, true,
+                   override_euuid);
                if (error != 0) {
                        if (route != NULL) {
                                rtfree(route);
                        }
-                       FREE(parsed_parameters, M_NECP);
-                       return (FALSE);
+                       return FALSE;
+               }
+
+               if (validate_agents) {
+                       bool requirement_failed = FALSE;
+                       if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT) {
+                               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                                       if (uuid_is_null(parsed_parameters->required_netagents[i])) {
+                                               break;
+                                       }
+
+                                       bool requirement_found = FALSE;
+                                       for (int j = 0; j < NECP_MAX_NETAGENTS; j++) {
+                                               if (uuid_is_null(result->netagents[j])) {
+                                                       break;
+                                               }
+
+                                               if (uuid_compare(parsed_parameters->required_netagents[i], result->netagents[j]) == 0) {
+                                                       requirement_found = TRUE;
+                                                       break;
+                                               }
+                                       }
+
+                                       if (!requirement_found) {
+                                               requirement_failed = TRUE;
+                                               break;
+                                       }
+                               }
+                       }
+
+                       if (!requirement_failed && parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE) {
+                               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                                       if (strlen(parsed_parameters->required_netagent_types[i].netagent_domain) == 0 &&
+                                           strlen(parsed_parameters->required_netagent_types[i].netagent_type) == 0) {
+                                               break;
+                                       }
+
+                                       bool requirement_found = FALSE;
+                                       for (int j = 0; j < NECP_MAX_NETAGENTS; j++) {
+                                               if (uuid_is_null(result->netagents[j])) {
+                                                       break;
+                                               }
+
+                                               char policy_agent_domain[NETAGENT_DOMAINSIZE] = { 0 };
+                                               char policy_agent_type[NETAGENT_TYPESIZE] = { 0 };
+
+                                               if (netagent_get_agent_domain_and_type(result->netagents[j], policy_agent_domain, policy_agent_type)) {
+                                                       if (necp_agent_types_match(parsed_parameters->required_netagent_types[i].netagent_domain,
+                                                           parsed_parameters->required_netagent_types[i].netagent_type,
+                                                           policy_agent_domain, policy_agent_type)) {
+                                                               requirement_found = TRUE;
+                                                               break;
+                                                       }
+                                               }
+                                       }
+
+                                       if (!requirement_found) {
+                                               requirement_failed = TRUE;
+                                               break;
+                                       }
+                               }
+                       }
+
+                       if (requirement_failed) {
+                               // Agent requirement failed. Clear out the whole result, make everything fail.
+                               memset(result, 0, sizeof(*result));
+                               if (route != NULL) {
+                                       rtfree(route);
+                               }
+                               return TRUE;
+                       }
                }
 
                // Reset current route
@@ -2169,15 +3212,82 @@ necp_update_client_result(proc_t proc,
                NECP_CLIENT_ROUTE_UNLOCK(client);
        } else {
                // Interface not found. Clear out the whole result, make everything fail.
-               memset(&result, 0, sizeof(result));
+               memset(result, 0, sizeof(*result));
+       }
+
+       return TRUE;
+}
+
+#define NECP_PARSED_PARAMETERS_REQUIRED_FIELDS (NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF |             \
+                                                                                               NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE |          \
+                                                                                               NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT |           \
+                                                                                               NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE)
+
+static bool
+necp_update_client_result(proc_t proc,
+    struct necp_fd_data *client_fd,
+    struct necp_client *client,
+    struct _necp_flow_defunct_list *defunct_list)
+{
+       struct necp_client_result_netagent netagent;
+       struct necp_aggregate_result result;
+       struct necp_client_parsed_parameters *parsed_parameters = NULL;
+       u_int32_t flags = 0;
+       u_int32_t reason = 0;
+
+       NECP_CLIENT_ASSERT_LOCKED(client);
+
+       MALLOC(parsed_parameters, struct necp_client_parsed_parameters *, sizeof(*parsed_parameters), M_NECP, (M_WAITOK | M_ZERO));
+       if (parsed_parameters == NULL) {
+               NECPLOG0(LOG_ERR, "Failed to allocate parsed parameters");
+               return FALSE;
+       }
+
+       // Nexus flows will be brought back if they are still valid
+       necp_client_mark_all_nonsocket_flows_as_invalid(client);
+
+       int error = necp_client_parse_parameters(client->parameters, (u_int32_t)client->parameters_length, parsed_parameters);
+       if (error != 0) {
+               FREE(parsed_parameters, M_NECP);
+               return FALSE;
+       }
+
+       // Update saved IP protocol
+       client->ip_protocol = parsed_parameters->ip_protocol;
+
+       // Calculate the policy result
+       struct necp_client_endpoint v4_gateway = {};
+       struct necp_client_endpoint v6_gateway = {};
+       uuid_t override_euuid;
+       uuid_clear(override_euuid);
+       if (!necp_calculate_client_result(proc, client, parsed_parameters, &result, &flags, &reason, &v4_gateway, &v6_gateway, &override_euuid)) {
+               FREE(parsed_parameters, M_NECP);
+               return FALSE;
+       }
+
+       if (necp_update_parsed_parameters(parsed_parameters, &result)) {
+               // Changed the parameters based on result, try again (only once)
+               if (!necp_calculate_client_result(proc, client, parsed_parameters, &result, &flags, &reason, &v4_gateway, &v6_gateway, &override_euuid)) {
+                       FREE(parsed_parameters, M_NECP);
+                       return FALSE;
+               }
+       }
+
+       if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) &&
+           parsed_parameters->required_interface_index != IFSCOPE_NONE &&
+           (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF) == 0) {
+               // Listener should not apply required interface index if
+               parsed_parameters->required_interface_index = IFSCOPE_NONE;
        }
 
        // Save the last policy id on the client
        client->policy_id = result.policy_id;
+       uuid_copy(client->override_euuid, override_euuid);
 
        if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_MULTIPATH) ||
-               ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) &&
-                result.routing_result != NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED)) {
+           (parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_BROWSE) ||
+           ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) &&
+           result.routing_result != NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED)) {
                client->allow_multiple_flows = TRUE;
        } else {
                client->allow_multiple_flows = FALSE;
@@ -2185,23 +3295,20 @@ necp_update_client_result(proc_t proc,
 
        // If the original request was scoped, and the policy result matches, make sure the result is scoped
        if ((result.routing_result == NECP_KERNEL_POLICY_RESULT_NONE ||
-                result.routing_result == NECP_KERNEL_POLICY_RESULT_PASS) &&
-               result.routed_interface_index != IFSCOPE_NONE &&
-               parsed_parameters->required_interface_index == result.routed_interface_index) {
+           result.routing_result == NECP_KERNEL_POLICY_RESULT_PASS) &&
+           result.routed_interface_index != IFSCOPE_NONE &&
+           parsed_parameters->required_interface_index == result.routed_interface_index) {
                result.routing_result = NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED;
                result.routing_result_parameter.scoped_interface_index = result.routed_interface_index;
        }
 
        if (defunct_list != NULL &&
-               result.routing_result == NECP_KERNEL_POLICY_RESULT_DROP) {
+           result.routing_result == NECP_KERNEL_POLICY_RESULT_DROP) {
                // If we are forced to drop the client, defunct it if it has flows
                necp_defunct_client_for_policy(client, defunct_list);
        }
 
        // Recalculate flags
-       if (client->defunct) {
-               flags |= NECP_CLIENT_RESULT_FLAG_DEFUNCT;
-       }
        if (parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) {
                // Listeners are valid as long as they aren't dropped
                if (result.routing_result != NECP_KERNEL_POLICY_RESULT_DROP) {
@@ -2215,62 +3322,102 @@ necp_update_client_result(proc_t proc,
        bool updated = FALSE;
        u_int8_t *cursor = client->result;
        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_FLAGS, sizeof(flags), &flags, &updated, client->result, sizeof(client->result));
+       if (reason != 0) {
+               cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_REASON, sizeof(reason), &reason, &updated, client->result, sizeof(client->result));
+       }
        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_CLIENT_ID, sizeof(uuid_t), client->client_id, &updated,
-                                                                                               client->result, sizeof(client->result));
+           client->result, sizeof(client->result));
        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_POLICY_RESULT, sizeof(result.routing_result), &result.routing_result, &updated,
-                                                                                               client->result, sizeof(client->result));
+           client->result, sizeof(client->result));
        if (result.routing_result_parameter.tunnel_interface_index != 0) {
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_POLICY_RESULT_PARAMETER,
-                                                                                                       sizeof(result.routing_result_parameter), &result.routing_result_parameter, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   sizeof(result.routing_result_parameter), &result.routing_result_parameter, &updated,
+                   client->result, sizeof(client->result));
        }
        if (result.filter_control_unit != 0) {
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_FILTER_CONTROL_UNIT,
-                                                                                                       sizeof(result.filter_control_unit), &result.filter_control_unit, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   sizeof(result.filter_control_unit), &result.filter_control_unit, &updated,
+                   client->result, sizeof(client->result));
        }
        if (result.routed_interface_index != 0) {
                u_int routed_interface_index = result.routed_interface_index;
                if (result.routing_result == NECP_KERNEL_POLICY_RESULT_IP_TUNNEL &&
-                       parsed_parameters->required_interface_index != IFSCOPE_NONE &&
-                       parsed_parameters->required_interface_index != result.routed_interface_index) {
+                   (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_REQUIRED_FIELDS) &&
+                   parsed_parameters->required_interface_index != IFSCOPE_NONE &&
+                   parsed_parameters->required_interface_index != result.routed_interface_index) {
                        routed_interface_index = parsed_parameters->required_interface_index;
                }
 
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE_INDEX,
-                                                                                                       sizeof(routed_interface_index), &routed_interface_index, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   sizeof(routed_interface_index), &routed_interface_index, &updated,
+                   client->result, sizeof(client->result));
        }
        if (client_fd && client_fd->flags & NECP_OPEN_FLAG_BACKGROUND) {
                u_int32_t effective_traffic_class = SO_TC_BK_SYS;
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_EFFECTIVE_TRAFFIC_CLASS,
-                                                                                                       sizeof(effective_traffic_class), &effective_traffic_class, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   sizeof(effective_traffic_class), &effective_traffic_class, &updated,
+                   client->result, sizeof(client->result));
        }
-       if (client->background_update) {
-               u_int32_t background = client->background;
-               cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_TRAFFIC_MGMT_BG,
-                                                                                                       sizeof(background), &background, &updated,
-                                                                                                       client->result, sizeof(client->result));
-               if (updated) {
-                       client->background_update = 0;
+
+       if (client_fd->background) {
+               bool has_assigned_flow = FALSE;
+               struct necp_client_flow_registration *flow_registration = NULL;
+               struct necp_client_flow *search_flow = NULL;
+               RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+                       LIST_FOREACH(search_flow, &flow_registration->flow_list, flow_chain) {
+                               if (search_flow->assigned) {
+                                       has_assigned_flow = TRUE;
+                                       break;
+                               }
+                       }
+               }
+
+               if (has_assigned_flow) {
+                       u_int32_t background = client_fd->background;
+                       cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_TRAFFIC_MGMT_BG,
+                           sizeof(background), &background, &updated,
+                           client->result, sizeof(client->result));
                }
        }
+
+       bool write_v4_gateway = !necp_client_endpoint_is_unspecified(&v4_gateway);
+       bool write_v6_gateway = !necp_client_endpoint_is_unspecified(&v6_gateway);
+
        NECP_CLIENT_ROUTE_LOCK(client);
        if (client->current_route != NULL) {
                const u_int32_t route_mtu = get_maxmtu(client->current_route);
                if (route_mtu != 0) {
                        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_EFFECTIVE_MTU,
-                                                                                                               sizeof(route_mtu), &route_mtu, &updated,
-                                                                                                               client->result, sizeof(client->result));
+                           sizeof(route_mtu), &route_mtu, &updated,
+                           client->result, sizeof(client->result));
+               }
+               bool has_remote_addr = parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REMOTE_ADDR;
+               if (has_remote_addr && client->current_route->rt_gateway != NULL) {
+                       if (client->current_route->rt_gateway->sa_family == AF_INET) {
+                               write_v6_gateway = false;
+                       } else if (client->current_route->rt_gateway->sa_family == AF_INET6) {
+                               write_v4_gateway = false;
+                       }
                }
        }
        NECP_CLIENT_ROUTE_UNLOCK(client);
 
+       if (write_v4_gateway) {
+               cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_GATEWAY,
+                   sizeof(struct necp_client_endpoint), &v4_gateway, &updated,
+                   client->result, sizeof(client->result));
+       }
+
+       if (write_v6_gateway) {
+               cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_GATEWAY,
+                   sizeof(struct necp_client_endpoint), &v6_gateway, &updated,
+                   client->result, sizeof(client->result));
+       }
+
        if (result.mss_recommended != 0) {
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_RECOMMENDED_MSS,
-                                                                                                       sizeof(result.mss_recommended), &result.mss_recommended, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   sizeof(result.mss_recommended), &result.mss_recommended, &updated,
+                   client->result, sizeof(client->result));
        }
 
        for (int i = 0; i < NECP_MAX_NETAGENTS; i++) {
@@ -2279,9 +3426,9 @@ necp_update_client_result(proc_t proc,
                }
                uuid_copy(netagent.netagent_uuid, result.netagents[i]);
                netagent.generation = netagent_get_generation(netagent.netagent_uuid);
-               if (necp_netagent_applies_to_client(client, parsed_parameters, netagent.netagent_uuid, TRUE, 0, 0)) {
+               if (necp_netagent_applies_to_client(client, parsed_parameters, &netagent.netagent_uuid, TRUE, 0, 0)) {
                        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_NETAGENT, sizeof(netagent), &netagent, &updated,
-                                                                                                               client->result, sizeof(client->result));
+                           client->result, sizeof(client->result));
                }
        }
 
@@ -2293,21 +3440,22 @@ necp_update_client_result(proc_t proc,
        if (result.routed_interface_index != IFSCOPE_NONE && result.routed_interface_index <= (u_int32_t)if_index) {
                direct_interface = ifindex2ifnet[result.routed_interface_index];
        } else if (parsed_parameters->required_interface_index != IFSCOPE_NONE &&
-                          parsed_parameters->required_interface_index <= (u_int32_t)if_index) {
+           parsed_parameters->required_interface_index <= (u_int32_t)if_index) {
                // If the request was scoped, but the route didn't match, still grab the agents
                direct_interface = ifindex2ifnet[parsed_parameters->required_interface_index];
        } else if (result.routed_interface_index == IFSCOPE_NONE &&
-                          result.routing_result == NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED &&
-                          result.routing_result_parameter.scoped_interface_index != IFSCOPE_NONE) {
+           result.routing_result == NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED &&
+           result.routing_result_parameter.scoped_interface_index != IFSCOPE_NONE) {
                direct_interface = ifindex2ifnet[result.routing_result_parameter.scoped_interface_index];
        }
        if (direct_interface != NULL) {
                delegate_interface = direct_interface->if_delegated.ifp;
        }
        if (result.routing_result == NECP_KERNEL_POLICY_RESULT_IP_TUNNEL &&
-               parsed_parameters->required_interface_index != IFSCOPE_NONE &&
-               parsed_parameters->required_interface_index != result.routing_result_parameter.tunnel_interface_index &&
-               parsed_parameters->required_interface_index <= (u_int32_t)if_index) {
+           (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_REQUIRED_FIELDS) &&
+           parsed_parameters->required_interface_index != IFSCOPE_NONE &&
+           parsed_parameters->required_interface_index != result.routing_result_parameter.tunnel_interface_index &&
+           parsed_parameters->required_interface_index <= (u_int32_t)if_index) {
                original_scoped_interface = ifindex2ifnet[parsed_parameters->required_interface_index];
        }
        // Add interfaces
@@ -2316,21 +3464,31 @@ necp_update_client_result(proc_t proc,
                interface_struct.index = original_scoped_interface->if_index;
                interface_struct.generation = ifnet_get_generation(original_scoped_interface);
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE, sizeof(interface_struct), &interface_struct, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   client->result, sizeof(client->result));
        }
        if (direct_interface != NULL) {
                struct necp_client_result_interface interface_struct;
                interface_struct.index = direct_interface->if_index;
                interface_struct.generation = ifnet_get_generation(direct_interface);
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE, sizeof(interface_struct), &interface_struct, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   client->result, sizeof(client->result));
+
+               // Set the delta time since interface up/down
+               struct timeval updown_delta = {};
+               if (ifnet_updown_delta(direct_interface, &updown_delta) == 0) {
+                       u_int32_t delta = updown_delta.tv_sec;
+                       bool ignore_updated = FALSE;
+                       cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE_TIME_DELTA,
+                           sizeof(delta), &delta, &ignore_updated,
+                           client->result, sizeof(client->result));
+               }
        }
        if (delegate_interface != NULL) {
                struct necp_client_result_interface interface_struct;
                interface_struct.index = delegate_interface->if_index;
                interface_struct.generation = ifnet_get_generation(delegate_interface);
                cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE, sizeof(interface_struct), &interface_struct, &updated,
-                                                                                                       client->result, sizeof(client->result));
+                   client->result, sizeof(client->result));
        }
 
        // Update multipath/listener interface flows
@@ -2338,22 +3496,50 @@ necp_update_client_result(proc_t proc,
                // Get multipath interface options from ordered list
                struct ifnet *multi_interface = NULL;
                TAILQ_FOREACH(multi_interface, &ifnet_ordered_head, if_ordered_link) {
-                       if (necp_ifnet_matches_parameters(multi_interface, parsed_parameters, NULL, true)) {
+                       if (necp_ifnet_matches_parameters(multi_interface, parsed_parameters, 0, NULL, true, false)) {
                                // Add multipath interface flows for kernel MPTCP
-                               necp_client_add_interface_flow_if_needed(client, multi_interface->if_index);
+                               necp_client_add_interface_option_if_needed(client, multi_interface->if_index,
+                                   ifnet_get_generation(multi_interface), NULL);
 
                                // Add nexus agents for multipath
-                               necp_client_add_agent_flows_for_interface(client, parsed_parameters, multi_interface);
+                               necp_client_add_agent_interface_options(client, parsed_parameters, multi_interface);
                        }
                }
-       } else if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) &&
-                          result.routing_result != NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED) {
-               // Get listener interface options from global list
-               struct ifnet *listen_interface = NULL;
-               TAILQ_FOREACH(listen_interface, &ifnet_head, if_link) {
-                       if (necp_ifnet_matches_parameters(listen_interface, parsed_parameters, NULL, false)) {
+       } else if (parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) {
+               if (result.routing_result == NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED) {
+                       if (direct_interface != NULL) {
+                               // If scoped, only listen on that interface
                                // Add nexus agents for listeners
-                               necp_client_add_agent_flows_for_interface(client, parsed_parameters, listen_interface);
+                               necp_client_add_agent_interface_options(client, parsed_parameters, direct_interface);
+
+                               // Add interface option in case it is not a nexus
+                               necp_client_add_interface_option_if_needed(client, direct_interface->if_index,
+                                   ifnet_get_generation(direct_interface), NULL);
+                       }
+               } else {
+                       // Get listener interface options from global list
+                       struct ifnet *listen_interface = NULL;
+                       TAILQ_FOREACH(listen_interface, &ifnet_head, if_link) {
+                               if ((listen_interface->if_flags & (IFF_UP | IFF_RUNNING)) &&
+                                   necp_ifnet_matches_parameters(listen_interface, parsed_parameters, 0, NULL, true, false)) {
+                                       // Add nexus agents for listeners
+                                       necp_client_add_agent_interface_options(client, parsed_parameters, listen_interface);
+                               }
+                       }
+               }
+       } else if (parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_BROWSE) {
+               if (result.routing_result == NECP_KERNEL_POLICY_RESULT_SOCKET_SCOPED) {
+                       if (direct_interface != NULL) {
+                               // Add browse option if it has an agent
+                               necp_client_add_browse_interface_options(client, parsed_parameters, direct_interface);
+                       }
+               } else {
+                       // Get browse interface options from global list
+                       struct ifnet *browse_interface = NULL;
+                       TAILQ_FOREACH(browse_interface, &ifnet_head, if_link) {
+                               if (necp_ifnet_matches_parameters(browse_interface, parsed_parameters, 0, NULL, true, false)) {
+                                       necp_client_add_browse_interface_options(client, parsed_parameters, browse_interface);
+                               }
                        }
                }
        }
@@ -2366,12 +3552,12 @@ necp_update_client_result(proc_t proc,
                                if (uuid_is_null(original_scoped_interface->if_agentids[i])) {
                                        continue;
                                }
-                               u_int16_t if_flags = nstat_ifnet_to_flags(original_scoped_interface);
                                uuid_copy(netagent.netagent_uuid, original_scoped_interface->if_agentids[i]);
                                netagent.generation = netagent_get_generation(netagent.netagent_uuid);
-                               if (necp_netagent_applies_to_client(client, parsed_parameters, netagent.netagent_uuid, FALSE, original_scoped_interface->if_index, if_flags)) {
+                               if (necp_netagent_applies_to_client(client, parsed_parameters, &netagent.netagent_uuid, FALSE,
+                                   original_scoped_interface->if_index, ifnet_get_generation(original_scoped_interface))) {
                                        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_NETAGENT, sizeof(netagent), &netagent, &updated,
-                                                                                                                               client->result, sizeof(client->result));
+                                           client->result, sizeof(client->result));
                                }
                        }
                }
@@ -2384,12 +3570,12 @@ necp_update_client_result(proc_t proc,
                                if (uuid_is_null(direct_interface->if_agentids[i])) {
                                        continue;
                                }
-                               u_int16_t if_flags = nstat_ifnet_to_flags(direct_interface);
                                uuid_copy(netagent.netagent_uuid, direct_interface->if_agentids[i]);
                                netagent.generation = netagent_get_generation(netagent.netagent_uuid);
-                               if (necp_netagent_applies_to_client(client, parsed_parameters, netagent.netagent_uuid, TRUE, direct_interface->if_index, if_flags)) {
+                               if (necp_netagent_applies_to_client(client, parsed_parameters, &netagent.netagent_uuid, TRUE,
+                                   direct_interface->if_index, ifnet_get_generation(direct_interface))) {
                                        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_NETAGENT, sizeof(netagent), &netagent, &updated,
-                                                                                                                               client->result, sizeof(client->result));
+                                           client->result, sizeof(client->result));
                                }
                        }
                }
@@ -2402,12 +3588,12 @@ necp_update_client_result(proc_t proc,
                                if (uuid_is_null(delegate_interface->if_agentids[i])) {
                                        continue;
                                }
-                               u_int16_t if_flags = nstat_ifnet_to_flags(delegate_interface);
                                uuid_copy(netagent.netagent_uuid, delegate_interface->if_agentids[i]);
                                netagent.generation = netagent_get_generation(netagent.netagent_uuid);
-                               if (necp_netagent_applies_to_client(client, parsed_parameters, netagent.netagent_uuid, FALSE, delegate_interface->if_index, if_flags)) {
+                               if (necp_netagent_applies_to_client(client, parsed_parameters, &netagent.netagent_uuid, FALSE,
+                                   delegate_interface->if_index, ifnet_get_generation(delegate_interface))) {
                                        cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_NETAGENT, sizeof(netagent), &netagent, &updated,
-                                                                                                                               client->result, sizeof(client->result));
+                                           client->result, sizeof(client->result));
                                }
                        }
                }
@@ -2415,6 +3601,19 @@ necp_update_client_result(proc_t proc,
        }
        ifnet_head_done();
 
+       // Add interface options
+       for (u_int32_t option_i = 0; option_i < client->interface_option_count; option_i++) {
+               if (option_i < NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT) {
+                       struct necp_client_interface_option *option = &client->interface_options[option_i];
+                       cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE_OPTION, sizeof(*option), option, &updated,
+                           client->result, sizeof(client->result));
+               } else {
+                       struct necp_client_interface_option *option = &client->extra_interface_options[option_i - NECP_CLIENT_INTERFACE_OPTION_STATIC_COUNT];
+                       cursor = necp_buffer_write_tlv_if_different(cursor, NECP_CLIENT_RESULT_INTERFACE_OPTION, sizeof(*option), option, &updated,
+                           client->result, sizeof(client->result));
+               }
+       }
+
        size_t new_result_length = (cursor - client->result);
        if (new_result_length != client->result_length) {
                client->result_length = new_result_length;
@@ -2422,7 +3621,7 @@ necp_update_client_result(proc_t proc,
        }
 
        // Update flow viability/flags
-       if (necp_client_update_flows(proc, client)) {
+       if (necp_client_update_flows(proc, client, defunct_list)) {
                updated = TRUE;
        }
 
@@ -2432,43 +3631,51 @@ necp_update_client_result(proc_t proc,
        }
 
        FREE(parsed_parameters, M_NECP);
-       return (updated);
+       return updated;
 }
 
 static inline void
-necp_defunct_client_fd_locked(struct necp_fd_data *client_fd, struct _necp_client_defunct_list *defunct_list)
+necp_defunct_client_fd_locked(struct necp_fd_data *client_fd, struct _necp_flow_defunct_list *defunct_list, struct proc *proc)
 {
+#pragma unused(proc)
        bool updated_result = FALSE;
        struct necp_client *client = NULL;
 
        NECP_FD_ASSERT_LOCKED(client_fd);
+
        RB_FOREACH(client, _necp_client_tree, &client_fd->clients) {
+               struct necp_client_flow_registration *flow_registration = NULL;
+
                NECP_CLIENT_LOCK(client);
-               if (!client->defunct) {
-                       updated_result = necp_set_client_defunct(client);
 
-                       // Prepare close events to be sent to the nexus to effectively remove the flows
-                       struct necp_client_flow *search_flow = NULL;
-                       LIST_FOREACH(search_flow, &client->flow_list, flow_chain) {
+               // Prepare close events to be sent to the nexus to effectively remove the flows
+               struct necp_client_flow *search_flow = NULL;
+               RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+                       LIST_FOREACH(search_flow, &flow_registration->flow_list, flow_chain) {
                                if (search_flow->nexus &&
-                                       !uuid_is_null(search_flow->u.nexus_agent) &&
-                                       search_flow->requested_nexus) {
-
-                                       struct necp_client_defunct *client_defunct;
-
+                                   !uuid_is_null(search_flow->u.nexus_agent)) {
                                        // Sleeping alloc won't fail; copy only what's necessary
-                                       client_defunct = _MALLOC(sizeof (struct necp_client_defunct), M_NECP, M_WAITOK | M_ZERO);
-                                       uuid_copy(client_defunct->nexus_agent, search_flow->u.nexus_agent);
-                                       uuid_copy(client_defunct->client_id, client->client_id);
-                                       client_defunct->proc_pid = client->proc_pid;
-
+                                       struct necp_flow_defunct *flow_defunct = _MALLOC(sizeof(struct necp_flow_defunct), M_NECP, M_WAITOK | M_ZERO);
+                                       uuid_copy(flow_defunct->nexus_agent, search_flow->u.nexus_agent);
+                                       uuid_copy(flow_defunct->flow_id, ((flow_registration->flags & NECP_CLIENT_FLOW_FLAGS_USE_CLIENT_ID) ?
+                                           client->client_id :
+                                           flow_registration->registration_id));
+                                       flow_defunct->proc_pid = client->proc_pid;
+                                       flow_defunct->agent_handle = client->agent_handle;
+                                       flow_defunct->flags = flow_registration->flags;
                                        // Add to the list provided by caller
-                                       LIST_INSERT_HEAD(defunct_list, client_defunct, chain);
+                                       LIST_INSERT_HEAD(defunct_list, flow_defunct, chain);
+
+                                       flow_registration->defunct = true;
+                                       flow_registration->flow_result_read = false;
+                                       updated_result = true;
                                }
                        }
                }
                NECP_CLIENT_UNLOCK(client);
        }
+
+
        if (updated_result) {
                necp_fd_notify(client_fd, true);
        }
@@ -2476,8 +3683,8 @@ necp_defunct_client_fd_locked(struct necp_fd_data *client_fd, struct _necp_clien
 
 static inline void
 necp_update_client_fd_locked(struct necp_fd_data *client_fd,
-                                                        proc_t proc,
-                                                        struct _necp_client_defunct_list *defunct_list)
+    proc_t proc,
+    struct _necp_flow_defunct_list *defunct_list)
 {
        struct necp_client *client = NULL;
        bool updated_result = FALSE;
@@ -2497,11 +3704,11 @@ necp_update_client_fd_locked(struct necp_fd_data *client_fd,
 
 static void
 necp_update_all_clients_callout(__unused thread_call_param_t dummy,
-                                                               __unused thread_call_param_t arg)
+    __unused thread_call_param_t arg)
 {
        struct necp_fd_data *client_fd = NULL;
 
-       struct _necp_client_defunct_list defunct_list;
+       struct _necp_flow_defunct_list defunct_list;
        LIST_INIT(&defunct_list);
 
        NECP_FD_LIST_LOCK_SHARED();
@@ -2525,22 +3732,34 @@ necp_update_all_clients_callout(__unused thread_call_param_t dummy,
 
        // Handle the case in which some clients became newly defunct
        if (!LIST_EMPTY(&defunct_list)) {
-               struct necp_client_defunct *client_defunct = NULL;
-               struct necp_client_defunct *temp_client_defunct = NULL;
+               struct necp_flow_defunct *flow_defunct = NULL;
+               struct necp_flow_defunct *temp_flow_defunct = NULL;
 
                // For each newly defunct client, send a message to the nexus to remove the flow
-               LIST_FOREACH_SAFE(client_defunct, &defunct_list, chain, temp_client_defunct) {
-                       if (!uuid_is_null(client_defunct->nexus_agent)) {
-                               int netagent_error = netagent_client_message(client_defunct->nexus_agent,
-                                                                                                                        client_defunct->client_id,
-                                                                                                                        client_defunct->proc_pid,
-                                                                                                                        NETAGENT_MESSAGE_TYPE_ABORT_NEXUS);
+               LIST_FOREACH_SAFE(flow_defunct, &defunct_list, chain, temp_flow_defunct) {
+                       if (!uuid_is_null(flow_defunct->nexus_agent)) {
+                               u_int8_t message_type = NETAGENT_MESSAGE_TYPE_ABORT_NEXUS;
+                               if (((flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_BROWSE) ||
+                                   (flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_RESOLVE)) &&
+                                   !(flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_ALLOW_NEXUS)) {
+                                       message_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
+                               }
+                               int netagent_error = netagent_client_message_with_params(flow_defunct->nexus_agent,
+                                   flow_defunct->flow_id,
+                                   flow_defunct->proc_pid,
+                                   flow_defunct->agent_handle,
+                                   message_type,
+                                   flow_defunct->has_close_parameters ? &flow_defunct->close_parameters : NULL,
+                                   NULL, 0);
                                if (netagent_error != 0) {
-                                       NECPLOG((netagent_error == ENOENT ? LOG_DEBUG : LOG_ERR), "necp_update_client abort nexus error (%d)", netagent_error);
+                                       char namebuf[MAXCOMLEN + 1];
+                                       (void) strlcpy(namebuf, "unknown", sizeof(namebuf));
+                                       proc_name(flow_defunct->proc_pid, namebuf, sizeof(namebuf));
+                                       NECPLOG((netagent_error == ENOENT ? LOG_DEBUG : LOG_ERR), "necp_update_client abort nexus error (%d) for pid %d %s", netagent_error, flow_defunct->proc_pid, namebuf);
                                }
                        }
-                       LIST_REMOVE(client_defunct, chain);
-                       FREE(client_defunct, M_NECP);
+                       LIST_REMOVE(flow_defunct, chain);
+                       FREE(flow_defunct, M_NECP);
                }
        }
        ASSERT(LIST_EMPTY(&defunct_list));
@@ -2549,100 +3768,86 @@ necp_update_all_clients_callout(__unused thread_call_param_t dummy,
 void
 necp_update_all_clients(void)
 {
-       if (necp_client_update_tcall == NULL) {
-               // Don't try to update clients if the module is not initialized
-               return;
-       }
-
-       uint64_t deadline = 0;
-       uint64_t leeway = 0;
-       clock_interval_to_deadline(necp_timeout_microseconds, NSEC_PER_USEC, &deadline);
-       clock_interval_to_absolutetime_interval(necp_timeout_leeway_microseconds, NSEC_PER_USEC, &leeway);
-
-       thread_call_enter_delayed_with_leeway(necp_client_update_tcall, NULL,
-                                                                                 deadline, leeway, THREAD_CALL_DELAY_LEEWAY);
+       necp_update_all_clients_immediately_if_needed(false);
 }
 
 void
-necp_set_client_as_background(proc_t proc,
-                                                         struct fileproc *fp,
-                                                         bool background)
+necp_update_all_clients_immediately_if_needed(bool should_update_immediately)
 {
-       bool updated_result = FALSE;
-       struct necp_client *client = NULL;
-
-       if (proc == PROC_NULL) {
-               NECPLOG0(LOG_ERR, "NULL proc");
-               return;
-       }
-
-       if (fp == NULL) {
-               NECPLOG0(LOG_ERR, "NULL fp");
+       if (necp_client_update_tcall == NULL) {
+               // Don't try to update clients if the module is not initialized
                return;
        }
 
-       struct necp_fd_data *client_fd = (struct necp_fd_data *)fp->f_fglob->fg_data;
-       if (client_fd == NULL) {
-               NECPLOG0(LOG_ERR, "Could not find client structure for backgrounded client");
-               return;
-       }
+       uint64_t deadline = 0;
+       uint64_t leeway = 0;
 
-       if (client_fd->necp_fd_type != necp_fd_type_client) {
-               // Not a client fd, ignore
-               NECPLOG0(LOG_ERR, "Not a client fd, ignore");
-               return;
+       uint32_t timeout_to_use = necp_timeout_microseconds;
+       uint32_t leeway_to_use = necp_timeout_leeway_microseconds;
+       if (should_update_immediately) {
+               timeout_to_use = 1000 * 10; // 10ms
+               leeway_to_use = 1000 * 10; // 10ms;
        }
 
-       NECP_FD_LOCK(client_fd);
-
-       RB_FOREACH(client, _necp_client_tree, &client_fd->clients) {
-               NECP_CLIENT_LOCK(client);
-
-               bool has_assigned_flow = FALSE;
-               struct necp_client_flow *search_flow = NULL;
-               LIST_FOREACH(search_flow, &client->flow_list, flow_chain) {
-                       if (search_flow->assigned) {
-                               has_assigned_flow = TRUE;
-                               break;
-                       }
-               }
-
-               if (has_assigned_flow) {
-                       client->background = background;
-                       client->background_update = TRUE;
-                       updated_result = TRUE;
-               }
+       clock_interval_to_deadline(timeout_to_use, NSEC_PER_USEC, &deadline);
+       clock_interval_to_absolutetime_interval(leeway_to_use, NSEC_PER_USEC, &leeway);
 
-               NECP_CLIENT_UNLOCK(client);
-       }
-       if (updated_result) {
-               necp_update_client_fd_locked(client_fd, proc, NULL);
-       }
-       NECP_FD_UNLOCK(client_fd);
+       thread_call_enter_delayed_with_leeway(necp_client_update_tcall, NULL,
+           deadline, leeway, THREAD_CALL_DELAY_LEEWAY);
 }
 
-void
-necp_defunct_client(proc_t proc,
-                                       struct fileproc *fp)
+bool
+necp_set_client_as_background(proc_t proc,
+    struct fileproc *fp,
+    bool background)
 {
-       struct _necp_client_defunct_list defunct_list;
-
        if (proc == PROC_NULL) {
-               NECPLOG0(LOG_ERR, "NULL proc passed to set as background");
-               return;
+               NECPLOG0(LOG_ERR, "NULL proc");
+               return FALSE;
        }
 
        if (fp == NULL) {
-               NECPLOG0(LOG_ERR, "NULL fp passed to set as background");
-               return;
+               NECPLOG0(LOG_ERR, "NULL fp");
+               return FALSE;
        }
 
        struct necp_fd_data *client_fd = (struct necp_fd_data *)fp->f_fglob->fg_data;
        if (client_fd == NULL) {
                NECPLOG0(LOG_ERR, "Could not find client structure for backgrounded client");
-               return;
+               return FALSE;
+       }
+
+       if (client_fd->necp_fd_type != necp_fd_type_client) {
+               // Not a client fd, ignore
+               NECPLOG0(LOG_ERR, "Not a client fd, ignore");
+               return FALSE;
        }
 
+       client_fd->background = background;
+
+       return TRUE;
+}
+
+void
+necp_fd_memstatus(proc_t proc, uint32_t status,
+    struct necp_fd_data *client_fd)
+{
+#pragma unused(proc, status, client_fd)
+       ASSERT(proc != PROC_NULL);
+       ASSERT(client_fd != NULL);
+
+       // Nothing to reap for the process or client for now,
+       // but this is where we would trigger that in future.
+}
+
+void
+necp_fd_defunct(proc_t proc, struct necp_fd_data *client_fd)
+{
+       struct _necp_flow_defunct_list defunct_list;
+
+       ASSERT(proc != PROC_NULL);
+       ASSERT(client_fd != NULL);
+
        if (client_fd->necp_fd_type != necp_fd_type_client) {
                // Not a client fd, ignore
                return;
@@ -2653,26 +3858,35 @@ necp_defunct_client(proc_t proc,
 
        // Need to hold lock so ntstats defunct the same set of clients
        NECP_FD_LOCK(client_fd);
-       necp_defunct_client_fd_locked(client_fd, &defunct_list);
+       necp_defunct_client_fd_locked(client_fd, &defunct_list, proc);
        NECP_FD_UNLOCK(client_fd);
 
        if (!LIST_EMPTY(&defunct_list)) {
-               struct necp_client_defunct *client_defunct = NULL;
-               struct necp_client_defunct *temp_client_defunct = NULL;
+               struct necp_flow_defunct *flow_defunct = NULL;
+               struct necp_flow_defunct *temp_flow_defunct = NULL;
 
                // For each defunct client, remove flow from the nexus
-               LIST_FOREACH_SAFE(client_defunct, &defunct_list, chain, temp_client_defunct) {
-                       if (!uuid_is_null(client_defunct->nexus_agent)) {
-                               int netagent_error = netagent_client_message(client_defunct->nexus_agent,
-                                                                                                                        client_defunct->client_id,
-                                                                                                                        client_defunct->proc_pid,
-                                                                                                                        NETAGENT_MESSAGE_TYPE_ABORT_NEXUS);
+               LIST_FOREACH_SAFE(flow_defunct, &defunct_list, chain, temp_flow_defunct) {
+                       if (!uuid_is_null(flow_defunct->nexus_agent)) {
+                               u_int8_t message_type = NETAGENT_MESSAGE_TYPE_ABORT_NEXUS;
+                               if (((flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_BROWSE) ||
+                                   (flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_RESOLVE)) &&
+                                   !(flow_defunct->flags & NECP_CLIENT_FLOW_FLAGS_ALLOW_NEXUS)) {
+                                       message_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
+                               }
+                               int netagent_error = netagent_client_message_with_params(flow_defunct->nexus_agent,
+                                   flow_defunct->flow_id,
+                                   flow_defunct->proc_pid,
+                                   flow_defunct->agent_handle,
+                                   message_type,
+                                   flow_defunct->has_close_parameters ? &flow_defunct->close_parameters : NULL,
+                                   NULL, 0);
                                if (netagent_error != 0) {
                                        NECPLOG((netagent_error == ENOENT ? LOG_DEBUG : LOG_ERR), "necp_defunct_client abort nexus error (%d)", netagent_error);
                                }
                        }
-                       LIST_REMOVE(client_defunct, chain);
-                       FREE(client_defunct, M_NECP);
+                       LIST_REMOVE(flow_defunct, chain);
+                       FREE(flow_defunct, M_NECP);
                }
        }
        ASSERT(LIST_EMPTY(&defunct_list));
@@ -2690,17 +3904,17 @@ necp_client_remove_agent_from_result(struct necp_client *client, uuid_t netagent
 
                size_t tlv_total_length = (sizeof(struct necp_tlv_header) + length);
                if (type == NECP_CLIENT_RESULT_NETAGENT &&
-                       length == sizeof(struct necp_client_result_netagent) &&
-                       (offset + tlv_total_length) <= client->result_length) {
+                   length == sizeof(struct necp_client_result_netagent) &&
+                   (offset + tlv_total_length) <= client->result_length) {
                        struct necp_client_result_netagent *value = ((struct necp_client_result_netagent *)(void *)
-                                                                                                                necp_buffer_get_tlv_value(result_buffer, offset, NULL));
+                           necp_buffer_get_tlv_value(result_buffer, offset, NULL));
                        if (uuid_compare(value->netagent_uuid, netagent_uuid) == 0) {
                                // Found a netagent to remove
                                // Shift bytes down to remove the tlv, and adjust total length
                                // Don't adjust the current offset
                                memmove(result_buffer + offset,
-                                               result_buffer + offset + tlv_total_length,
-                                               client->result_length - (offset + tlv_total_length));
+                                   result_buffer + offset + tlv_total_length,
+                                   client->result_length - (offset + tlv_total_length));
                                client->result_length -= tlv_total_length;
                                memset(result_buffer + client->result_length, 0, sizeof(client->result) - client->result_length);
                                continue;
@@ -2712,7 +3926,7 @@ necp_client_remove_agent_from_result(struct necp_client *client, uuid_t netagent
 }
 
 void
-necp_force_update_client(uuid_t client_id, uuid_t remove_netagent_uuid)
+necp_force_update_client(uuid_t client_id, uuid_t remove_netagent_uuid, u_int32_t agent_generation)
 {
        struct necp_fd_data *client_fd = NULL;
 
@@ -2723,10 +3937,12 @@ necp_force_update_client(uuid_t client_id, uuid_t remove_netagent_uuid)
                NECP_FD_LOCK(client_fd);
                struct necp_client *client = necp_client_fd_find_client_and_lock(client_fd, client_id);
                if (client != NULL) {
+                       client->failed_trigger_agent.generation = agent_generation;
+                       uuid_copy(client->failed_trigger_agent.netagent_uuid, remove_netagent_uuid);
                        if (!uuid_is_null(remove_netagent_uuid)) {
                                necp_client_remove_agent_from_result(client, remove_netagent_uuid);
                        }
-                       client->flow_result_read = FALSE;
+                       client->result_read = FALSE;
                        // Found the client, break
                        updated_result = TRUE;
                        NECP_CLIENT_UNLOCK(client);
@@ -2747,26 +3963,33 @@ necp_force_update_client(uuid_t client_id, uuid_t remove_netagent_uuid)
 
 /// Interface matching
 
-#define NECP_PARSED_PARAMETERS_INTERESTING_IFNET_FIELDS (NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR |                             \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF |                   \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE |                 \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE |               \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT |                  \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT |                \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT |                 \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE |             \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE |   \
-                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE)
-
-#define NECP_PARSED_PARAMETERS_SCOPED_IFNET_FIELDS (NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR |                  \
-                                                                                                       NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE |          \
-                                                                                                       NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT |           \
-                                                                                                       NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT |          \
-                                                                                                       NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE |      \
-                                                                                                       NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE)
-
-#define NECP_PARSED_PARAMETERS_PREFERRED_IFNET_FIELDS (NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT | \
-                                                                                                          NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE)
+#define NECP_PARSED_PARAMETERS_INTERESTING_IFNET_FIELDS (NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR |                              \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF |                   \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE |                 \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE |               \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT |                  \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT |                \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT |                 \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT |                   \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE |             \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE |   \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE |    \
+                                                                                                                NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT_TYPE)
+
+#define NECP_PARSED_PARAMETERS_SCOPED_FIELDS (NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR |                 \
+                                                                                         NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE |                \
+                                                                                         NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT |         \
+                                                                                         NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT |                \
+                                                                                         NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE |    \
+                                                                                         NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE)
+
+#define NECP_PARSED_PARAMETERS_SCOPED_IFNET_FIELDS (NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR |           \
+                                                                                                       NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE)
+
+#define NECP_PARSED_PARAMETERS_PREFERRED_FIELDS (NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT |                 \
+                                                                                                NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT |                   \
+                                                                                                NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE |    \
+                                                                                                NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT_TYPE)
 
 static bool
 necp_ifnet_matches_type(struct ifnet *ifp, u_int8_t interface_type, bool check_delegates)
@@ -2774,15 +3997,14 @@ necp_ifnet_matches_type(struct ifnet *ifp, u_int8_t interface_type, bool check_d
        struct ifnet *check_ifp = ifp;
        while (check_ifp) {
                if (if_functional_type(check_ifp, TRUE) == interface_type) {
-                       return (TRUE);
+                       return TRUE;
                }
                if (!check_delegates) {
                        break;
                }
                check_ifp = check_ifp->if_delegated.ifp;
-
        }
-       return (FALSE);
+       return FALSE;
 }
 
 static bool
@@ -2791,14 +4013,14 @@ necp_ifnet_matches_name(struct ifnet *ifp, const char *interface_name, bool chec
        struct ifnet *check_ifp = ifp;
        while (check_ifp) {
                if (strncmp(check_ifp->if_xname, interface_name, IFXNAMSIZ) == 0) {
-                       return (TRUE);
+                       return TRUE;
                }
                if (!check_delegates) {
                        break;
                }
                check_ifp = check_ifp->if_delegated.ifp;
        }
-       return (FALSE);
+       return FALSE;
 }
 
 static bool
@@ -2812,7 +4034,7 @@ necp_ifnet_matches_agent(struct ifnet *ifp, uuid_t *agent_uuid, bool check_deleg
                        for (u_int32_t index = 0; index < check_ifp->if_agentcount; index++) {
                                if (uuid_compare(check_ifp->if_agentids[index], *agent_uuid) == 0) {
                                        ifnet_lock_done(check_ifp);
-                                       return (TRUE);
+                                       return TRUE;
                                }
                        }
                }
@@ -2823,11 +4045,11 @@ necp_ifnet_matches_agent(struct ifnet *ifp, uuid_t *agent_uuid, bool check_deleg
                }
                check_ifp = check_ifp->if_delegated.ifp;
        }
-       return (FALSE);
+       return FALSE;
 }
 
 static bool
-necp_necp_ifnet_matches_agent_type(struct ifnet *ifp, const char *agent_domain, const char *agent_type, bool check_delegates)
+necp_ifnet_matches_agent_type(struct ifnet *ifp, const char *agent_domain, const char *agent_type, bool check_delegates)
 {
        struct ifnet *check_ifp = ifp;
 
@@ -2843,13 +4065,10 @@ necp_necp_ifnet_matches_agent_type(struct ifnet *ifp, const char *agent_domain,
                                char if_agent_type[NETAGENT_TYPESIZE] = { 0 };
 
                                if (netagent_get_agent_domain_and_type(check_ifp->if_agentids[index], if_agent_domain, if_agent_type)) {
-                                       if ((strlen(agent_domain) == 0 ||
-                                                strncmp(if_agent_domain, agent_domain, NETAGENT_DOMAINSIZE) == 0) &&
-                                               (strlen(agent_type) == 0 ||
-                                                strncmp(if_agent_type, agent_type, NETAGENT_TYPESIZE) == 0)) {
-                                                       ifnet_lock_done(check_ifp);
-                                                       return (TRUE);
-                                               }
+                                       if (necp_agent_types_match(agent_domain, agent_type, if_agent_domain, if_agent_type)) {
+                                               ifnet_lock_done(check_ifp);
+                                               return TRUE;
+                                       }
                                }
                        }
                }
@@ -2860,7 +4079,7 @@ necp_necp_ifnet_matches_agent_type(struct ifnet *ifp, const char *agent_domain,
                }
                check_ifp = check_ifp->if_delegated.ifp;
        }
-       return (FALSE);
+       return FALSE;
 }
 
 static bool
@@ -2886,125 +4105,172 @@ necp_ifnet_matches_local_address(struct ifnet *ifp, struct sockaddr *sa)
                ifaddr_release(ifa);
        }
 
-       return (matched_local_address);
+       return matched_local_address;
 }
 
 static bool
 necp_interface_type_is_primary_eligible(u_int8_t interface_type)
 {
        switch (interface_type) {
-               // These types can never be primary, so a client requesting these types is allowed
-               // to match an interface that isn't currently eligible to be primary (has default
-               // route, dns, etc)
-               case IFRTYPE_FUNCTIONAL_WIFI_AWDL:
-               case IFRTYPE_FUNCTIONAL_INTCOPROC:
-                       return false;
-               default:
-                       break;
+       // These types can never be primary, so a client requesting these types is allowed
+       // to match an interface that isn't currently eligible to be primary (has default
+       // route, dns, etc)
+       case IFRTYPE_FUNCTIONAL_WIFI_AWDL:
+       case IFRTYPE_FUNCTIONAL_INTCOPROC:
+               return false;
+       default:
+               break;
        }
        return true;
 }
 
 #define NECP_IFP_IS_ON_ORDERED_LIST(_ifp) ((_ifp)->if_ordered_link.tqe_next != NULL || (_ifp)->if_ordered_link.tqe_prev != NULL)
 
+// Secondary interface flag indicates that the interface is being
+// used for multipath or a listener as an extra path
 static bool
 necp_ifnet_matches_parameters(struct ifnet *ifp,
-                                                         struct necp_client_parsed_parameters *parsed_parameters,
-                                                         u_int32_t *preferred_count, bool ignore_require_if)
+    struct necp_client_parsed_parameters *parsed_parameters,
+    u_int32_t override_flags,
+    u_int32_t *preferred_count,
+    bool secondary_interface,
+    bool require_scoped_field)
 {
+       bool matched_some_scoped_field = FALSE;
+
        if (preferred_count) {
                *preferred_count = 0;
        }
 
+       if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IF) {
+               if (parsed_parameters->required_interface_index != ifp->if_index) {
+                       return FALSE;
+               }
+       }
+
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR) {
                if (!necp_ifnet_matches_local_address(ifp, &parsed_parameters->local_addr.sa)) {
-                       return (FALSE);
+                       return FALSE;
+               }
+               if (require_scoped_field) {
+                       matched_some_scoped_field = TRUE;
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_FLAGS) {
-               if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_EXPENSIVE) &&
-                       IFNET_IS_EXPENSIVE(ifp)) {
-                       return (FALSE);
+               if (override_flags != 0) {
+                       if ((override_flags & NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_EXPENSIVE) &&
+                           IFNET_IS_EXPENSIVE(ifp)) {
+                               return FALSE;
+                       }
+                       if ((override_flags & NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_CONSTRAINED) &&
+                           IFNET_IS_CONSTRAINED(ifp)) {
+                               return FALSE;
+                       }
+               } else {
+                       if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_EXPENSIVE) &&
+                           IFNET_IS_EXPENSIVE(ifp)) {
+                               return FALSE;
+                       }
+                       if ((parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_CONSTRAINED) &&
+                           IFNET_IS_CONSTRAINED(ifp)) {
+                               return FALSE;
+                       }
                }
        }
 
-       if (!ignore_require_if &&
+       if ((!secondary_interface || // Enforce interface type if this is the primary interface
+           !(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_FLAGS) ||      // or if there are no flags
+           !(parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_ONLY_PRIMARY_REQUIRES_TYPE)) &&      // or if the flags don't give an exception
            (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE) &&
-               !necp_ifnet_matches_type(ifp, parsed_parameters->required_interface_type, FALSE)) {
-               return (FALSE);
+           !necp_ifnet_matches_type(ifp, parsed_parameters->required_interface_type, FALSE)) {
+               return FALSE;
+       }
+
+       if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE) {
+               if (require_scoped_field) {
+                       matched_some_scoped_field = TRUE;
+               }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IFTYPE) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_INTERFACE_PARAMETERS; i++) {
                        if (parsed_parameters->prohibited_interface_types[i] == 0) {
                                break;
                        }
 
                        if (necp_ifnet_matches_type(ifp, parsed_parameters->prohibited_interface_types[i], TRUE)) {
-                               return (FALSE);
+                               return FALSE;
                        }
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_IF) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_INTERFACE_PARAMETERS; i++) {
                        if (strlen(parsed_parameters->prohibited_interfaces[i]) == 0) {
                                break;
                        }
 
                        if (necp_ifnet_matches_name(ifp, parsed_parameters->prohibited_interfaces[i], TRUE)) {
-                               return (FALSE);
+                               return FALSE;
                        }
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                        if (uuid_is_null(parsed_parameters->required_netagents[i])) {
                                break;
                        }
 
                        if (!necp_ifnet_matches_agent(ifp, &parsed_parameters->required_netagents[i], FALSE)) {
-                               return (FALSE);
+                               return FALSE;
+                       }
+
+                       if (require_scoped_field) {
+                               matched_some_scoped_field = TRUE;
                        }
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                        if (uuid_is_null(parsed_parameters->prohibited_netagents[i])) {
                                break;
                        }
 
                        if (necp_ifnet_matches_agent(ifp, &parsed_parameters->prohibited_netagents[i], TRUE)) {
-                               return (FALSE);
+                               return FALSE;
                        }
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_AGENT_TYPE) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                        if (strlen(parsed_parameters->required_netagent_types[i].netagent_domain) == 0 &&
-                               strlen(parsed_parameters->required_netagent_types[i].netagent_type) == 0) {
+                           strlen(parsed_parameters->required_netagent_types[i].netagent_type) == 0) {
                                break;
                        }
 
-                       if (!necp_necp_ifnet_matches_agent_type(ifp, parsed_parameters->required_netagent_types[i].netagent_domain, parsed_parameters->required_netagent_types[i].netagent_type, FALSE)) {
-                               return (FALSE);
+                       if (!necp_ifnet_matches_agent_type(ifp, parsed_parameters->required_netagent_types[i].netagent_domain, parsed_parameters->required_netagent_types[i].netagent_type, FALSE)) {
+                               return FALSE;
+                       }
+
+                       if (require_scoped_field) {
+                               matched_some_scoped_field = TRUE;
                        }
                }
        }
 
        if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PROHIBITED_AGENT_TYPE) {
-               for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+               for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                        if (strlen(parsed_parameters->prohibited_netagent_types[i].netagent_domain) == 0 &&
-                               strlen(parsed_parameters->prohibited_netagent_types[i].netagent_type) == 0) {
+                           strlen(parsed_parameters->prohibited_netagent_types[i].netagent_type) == 0) {
                                break;
                        }
 
-                       if (necp_necp_ifnet_matches_agent_type(ifp, parsed_parameters->prohibited_netagent_types[i].netagent_domain, parsed_parameters->prohibited_netagent_types[i].netagent_type, TRUE)) {
-                               return (FALSE);
+                       if (necp_ifnet_matches_agent_type(ifp, parsed_parameters->prohibited_netagent_types[i].netagent_domain, parsed_parameters->prohibited_netagent_types[i].netagent_type, TRUE)) {
+                               return FALSE;
                        }
                }
        }
@@ -3012,36 +4278,73 @@ necp_ifnet_matches_parameters(struct ifnet *ifp,
        // Checked preferred properties
        if (preferred_count) {
                if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT) {
-                       for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+                       for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                                if (uuid_is_null(parsed_parameters->preferred_netagents[i])) {
                                        break;
                                }
 
                                if (necp_ifnet_matches_agent(ifp, &parsed_parameters->preferred_netagents[i], TRUE)) {
                                        (*preferred_count)++;
+                                       if (require_scoped_field) {
+                                               matched_some_scoped_field = TRUE;
+                                       }
                                }
                        }
                }
 
                if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_PREFERRED_AGENT_TYPE) {
-                       for (int i = 0; i < NECP_MAX_PARSED_PARAMETERS; i++) {
+                       for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
                                if (strlen(parsed_parameters->preferred_netagent_types[i].netagent_domain) == 0 &&
-                                       strlen(parsed_parameters->preferred_netagent_types[i].netagent_type) == 0) {
+                                   strlen(parsed_parameters->preferred_netagent_types[i].netagent_type) == 0) {
+                                       break;
+                               }
+
+                               if (necp_ifnet_matches_agent_type(ifp, parsed_parameters->preferred_netagent_types[i].netagent_domain, parsed_parameters->preferred_netagent_types[i].netagent_type, TRUE)) {
+                                       (*preferred_count)++;
+                                       if (require_scoped_field) {
+                                               matched_some_scoped_field = TRUE;
+                                       }
+                               }
+                       }
+               }
+
+               if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT) {
+                       for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                               if (uuid_is_null(parsed_parameters->avoided_netagents[i])) {
+                                       break;
+                               }
+
+                               if (!necp_ifnet_matches_agent(ifp, &parsed_parameters->avoided_netagents[i], TRUE)) {
+                                       (*preferred_count)++;
+                               }
+                       }
+               }
+
+               if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_AVOIDED_AGENT_TYPE) {
+                       for (int i = 0; i < NECP_MAX_AGENT_PARAMETERS; i++) {
+                               if (strlen(parsed_parameters->avoided_netagent_types[i].netagent_domain) == 0 &&
+                                   strlen(parsed_parameters->avoided_netagent_types[i].netagent_type) == 0) {
                                        break;
                                }
 
-                               if (necp_necp_ifnet_matches_agent_type(ifp, parsed_parameters->preferred_netagent_types[i].netagent_domain, parsed_parameters->preferred_netagent_types[i].netagent_type, TRUE)) {
+                               if (!necp_ifnet_matches_agent_type(ifp, parsed_parameters->avoided_netagent_types[i].netagent_domain,
+                                   parsed_parameters->avoided_netagent_types[i].netagent_type, TRUE)) {
                                        (*preferred_count)++;
                                }
                        }
                }
        }
 
-       return (TRUE);
+       if (require_scoped_field) {
+               return matched_some_scoped_field;
+       }
+
+       return TRUE;
 }
 
 static bool
-necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_parameters, u_int *return_ifindex)
+necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_parameters,
+    u_int *return_ifindex, bool *validate_agents)
 {
        struct ifnet *ifp = NULL;
        u_int32_t best_preferred_count = 0;
@@ -3050,36 +4353,47 @@ necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_
 
        if (parsed_parameters->required_interface_index != 0) {
                *return_ifindex = parsed_parameters->required_interface_index;
-               return (TRUE);
+               return TRUE;
+       }
+
+       // Check and save off flags
+       u_int32_t flags = 0;
+       bool has_prohibit_flags = FALSE;
+       if (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_FLAGS) {
+               flags = parsed_parameters->flags;
+               has_prohibit_flags = (parsed_parameters->flags &
+                   (NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_EXPENSIVE |
+                   NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_CONSTRAINED));
        }
 
-       if (!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_INTERESTING_IFNET_FIELDS)) {
-               return (TRUE);
+       if (!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_INTERESTING_IFNET_FIELDS) &&
+           !has_prohibit_flags) {
+               return TRUE;
        }
 
-       has_preferred_fields = (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_PREFERRED_IFNET_FIELDS);
+       has_preferred_fields = (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_PREFERRED_FIELDS);
 
        // We have interesting parameters to parse and find a matching interface
        ifnet_head_lock_shared();
 
-       if (!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_SCOPED_IFNET_FIELDS)) {
+       if (!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_SCOPED_FIELDS) &&
+           !has_preferred_fields) {
                // We do have fields to match, but they are only prohibitory
                // If the first interface in the list matches, or there are no ordered interfaces, we don't need to scope
                ifp = TAILQ_FIRST(&ifnet_ordered_head);
-               if (ifp == NULL || necp_ifnet_matches_parameters(ifp, parsed_parameters, NULL, false)) {
+               if (ifp == NULL || necp_ifnet_matches_parameters(ifp, parsed_parameters, 0, NULL, false, false)) {
                        // Don't set return_ifindex, so the client doesn't need to scope
                        ifnet_head_done();
-                       return (TRUE);
+                       return TRUE;
                }
        }
 
        // First check the ordered interface list
        TAILQ_FOREACH(ifp, &ifnet_ordered_head, if_ordered_link) {
                u_int32_t preferred_count = 0;
-               if (necp_ifnet_matches_parameters(ifp, parsed_parameters, &preferred_count, false)) {
+               if (necp_ifnet_matches_parameters(ifp, parsed_parameters, flags, &preferred_count, false, false)) {
                        if (preferred_count > best_preferred_count ||
-                               *return_ifindex == 0) {
-
+                           *return_ifindex == 0) {
                                // Everything matched, and is most preferred. Return this interface.
                                *return_ifindex = ifp->if_index;
                                best_preferred_count = preferred_count;
@@ -3089,23 +4403,36 @@ necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_
                                }
                        }
                }
+
+               if (has_prohibit_flags &&
+                   ifp == TAILQ_FIRST(&ifnet_ordered_head)) {
+                       // This was the first interface. From here on, if the
+                       // client prohibited either expensive or constrained,
+                       // don't allow either as a secondary interface option.
+                       flags |= (NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_EXPENSIVE |
+                           NECP_CLIENT_PARAMETER_FLAG_PROHIBIT_CONSTRAINED);
+               }
        }
 
+       bool is_listener = ((parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_FLAGS) &&
+           (parsed_parameters->flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER));
+
        // Then check the remaining interfaces
-       if ((parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_SCOPED_IFNET_FIELDS) &&
-               ((!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE)) ||
-                !necp_interface_type_is_primary_eligible(parsed_parameters->required_interface_type)) &&
-               *return_ifindex == 0) {
+       if ((parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_SCOPED_FIELDS) &&
+           ((!(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_REQUIRED_IFTYPE)) ||
+           !necp_interface_type_is_primary_eligible(parsed_parameters->required_interface_type) ||
+           (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR) ||
+           is_listener) &&
+           (*return_ifindex == 0 || has_preferred_fields)) {
                TAILQ_FOREACH(ifp, &ifnet_head, if_link) {
                        u_int32_t preferred_count = 0;
                        if (NECP_IFP_IS_ON_ORDERED_LIST(ifp)) {
                                // This interface was in the ordered list, skip
                                continue;
                        }
-                       if (necp_ifnet_matches_parameters(ifp, parsed_parameters, &preferred_count, false)) {
+                       if (necp_ifnet_matches_parameters(ifp, parsed_parameters, flags, &preferred_count, false, true)) {
                                if (preferred_count > best_preferred_count ||
-                                       *return_ifindex == 0) {
-
+                                   *return_ifindex == 0) {
                                        // Everything matched, and is most preferred. Return this interface.
                                        *return_ifindex = ifp->if_index;
                                        best_preferred_count = preferred_count;
@@ -3120,14 +4447,22 @@ necp_find_matching_interface_index(struct necp_client_parsed_parameters *parsed_
 
        ifnet_head_done();
 
-       if ((parsed_parameters->valid_fields == (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_PREFERRED_IFNET_FIELDS)) &&
-               best_preferred_count == 0) {
+       if ((parsed_parameters->valid_fields == (parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_PREFERRED_FIELDS)) &&
+           best_preferred_count == 0) {
                // If only has preferred fields, and nothing was found, clear the interface index and return TRUE
                *return_ifindex = 0;
-               return (TRUE);
+               return TRUE;
+       }
+
+       if (*return_ifindex == 0 &&
+           !(parsed_parameters->valid_fields & NECP_PARSED_PARAMETERS_SCOPED_IFNET_FIELDS)) {
+               // Has required fields, but not including specific interface fields. Pass for now, and check
+               // to see if agents are satisfied by policy.
+               *validate_agents = TRUE;
+               return TRUE;
        }
 
-       return (*return_ifindex != 0);
+       return *return_ifindex != 0;
 }
 
 
@@ -3135,7 +4470,7 @@ static int
 necp_skywalk_priv_check_cred(proc_t p, kauth_cred_t cred)
 {
 #pragma unused(p, cred)
-       return (0);
+       return 0;
 }
 
 /// System calls
@@ -3149,9 +4484,10 @@ necp_open(struct proc *p, struct necp_open_args *uap, int *retval)
        struct fileproc *fp = NULL;
        int fd = -1;
 
-       if (uap->flags & NECP_OPEN_FLAG_OBSERVER) {
+       if (uap->flags & NECP_OPEN_FLAG_OBSERVER ||
+           uap->flags & NECP_OPEN_FLAG_PUSH_OBSERVER) {
                if (necp_skywalk_priv_check_cred(p, kauth_cred_get()) != 0 &&
-                       priv_check_cred(kauth_cred_get(), PRIV_NET_PRIVILEGED_NETWORK_STATISTICS, 0) != 0) {
+                   priv_check_cred(kauth_cred_get(), PRIV_NET_PRIVILEGED_NETWORK_STATISTICS, 0) != 0) {
                        NECPLOG0(LOG_ERR, "Client does not hold necessary entitlement to observe other NECP clients");
                        error = EACCES;
                        goto done;
@@ -3173,6 +4509,7 @@ necp_open(struct proc *p, struct necp_open_args *uap, int *retval)
        fd_data->necp_fd_type = necp_fd_type_client;
        fd_data->flags = uap->flags;
        RB_INIT(&fd_data->clients);
+       RB_INIT(&fd_data->flows);
        TAILQ_INIT(&fd_data->update_list);
        lck_mtx_init(&fd_data->fd_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
        klist_init(&fd_data->si.si_note);
@@ -3227,10 +4564,15 @@ done:
                }
        }
 
-       return (error);
+       return error;
 }
 
-static int
+// All functions called directly from necp_client_action() to handle one of the
+// types should be marked with NECP_CLIENT_ACTION_FUNCTION. This ensures that
+// necp_client_action() does not inline all the actions into a single function.
+#define NECP_CLIENT_ACTION_FUNCTION __attribute__((noinline))
+
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_add(struct proc *p, struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -3238,16 +4580,16 @@ necp_client_add(struct proc *p, struct necp_fd_data *fd_data, struct necp_client
 
        if (fd_data->flags & NECP_OPEN_FLAG_PUSH_OBSERVER) {
                NECPLOG0(LOG_ERR, "NECP client observers with push enabled may not add their own clients");
-               return (EINVAL);
+               return EINVAL;
        }
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t) ||
-               uap->buffer_size == 0 || uap->buffer_size > NECP_MAX_CLIENT_PARAMETERS_SIZE || uap->buffer == 0) {
-               return (EINVAL);
+           uap->buffer_size == 0 || uap->buffer_size > NECP_MAX_CLIENT_PARAMETERS_SIZE || uap->buffer == 0) {
+               return EINVAL;
        }
 
        if ((client = _MALLOC(sizeof(struct necp_client) + uap->buffer_size, M_NECP,
-                                                 M_WAITOK | M_ZERO)) == NULL) {
+           M_WAITOK | M_ZERO)) == NULL) {
                error = ENOMEM;
                goto done;
        }
@@ -3260,15 +4602,17 @@ necp_client_add(struct proc *p, struct necp_fd_data *fd_data, struct necp_client
 
        lck_mtx_init(&client->lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
        lck_mtx_init(&client->route_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
-       necp_client_retain(client); // Hold our reference until close
+
+       os_ref_init(&client->reference_count, &necp_client_refgrp); // Hold our reference until close
 
        client->parameters_length = uap->buffer_size;
        client->proc_pid = fd_data->proc_pid; // Save off proc pid in case the client will persist past fd
+       client->agent_handle = (void *)fd_data;
        client->platform_binary = ((csproc_get_platform_binary(p) == 0) ? 0 : 1);
 
-       uuid_generate_random(client->client_id);
+       necp_generate_client_id(client->client_id, false);
        LIST_INIT(&client->assertion_list);
-       LIST_INIT(&client->flow_list);
+       RB_INIT(&client->flow_registrations);
 
        error = copyout(client->client_id, uap->client_id, sizeof(uuid_t));
        if (error) {
@@ -3276,6 +4620,7 @@ necp_client_add(struct proc *p, struct necp_fd_data *fd_data, struct necp_client
                goto done;
        }
 
+
        necp_client_update_observer_add(client);
 
        NECP_FD_LOCK(fd_data);
@@ -3299,15 +4644,80 @@ done:
        }
        *retval = error;
 
-       return (error);
+       return error;
 }
 
-static int
-necp_client_remove(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
+static NECP_CLIENT_ACTION_FUNCTION int
+necp_client_claim(struct proc *p, struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
+       uuid_t client_id = {};
        struct necp_client *client = NULL;
-       struct necp_client *temp_client = NULL;
+
+       if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t)) {
+               error = EINVAL;
+               goto done;
+       }
+
+       error = copyin(uap->client_id, client_id, sizeof(uuid_t));
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_claim copyin client_id error (%d)", error);
+               goto done;
+       }
+
+       u_int64_t upid = proc_uniqueid(p);
+
+       NECP_FD_LIST_LOCK_SHARED();
+
+       struct necp_fd_data *find_fd = NULL;
+       LIST_FOREACH(find_fd, &necp_fd_list, chain) {
+               NECP_FD_LOCK(find_fd);
+               struct necp_client *find_client = necp_client_fd_find_client_and_lock(find_fd, client_id);
+               if (find_client != NULL) {
+                       if (find_client->delegated_upid == upid) {
+                               // Matched the client to claim; remove from the old fd
+                               client = find_client;
+                               RB_REMOVE(_necp_client_tree, &find_fd->clients, client);
+                               necp_client_retain_locked(client);
+                       }
+                       NECP_CLIENT_UNLOCK(find_client);
+               }
+               NECP_FD_UNLOCK(find_fd);
+
+               if (client != NULL) {
+                       break;
+               }
+       }
+
+       NECP_FD_LIST_UNLOCK();
+
+       if (client == NULL) {
+               error = ENOENT;
+               goto done;
+       }
+
+       client->proc_pid = fd_data->proc_pid; // Transfer client to claiming pid
+
+       // Add matched client to our fd and re-run result
+       NECP_FD_LOCK(fd_data);
+       RB_INSERT(_necp_client_tree, &fd_data->clients, client);
+       NECP_CLIENT_LOCK(client);
+       (void)necp_update_client_result(current_proc(), fd_data, client, NULL);
+       NECP_CLIENT_UNLOCK(client);
+       NECP_FD_UNLOCK(fd_data);
+
+       necp_client_release(client);
+
+done:
+       *retval = error;
+
+       return error;
+}
+
+static NECP_CLIENT_ACTION_FUNCTION int
+necp_client_remove(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
+{
+       int error = 0;
        uuid_t client_id = {};
        struct ifnet_stats_per_flow flow_ifnet_stats = {};
 
@@ -3326,77 +4736,93 @@ necp_client_remove(struct necp_fd_data *fd_data, struct necp_client_action_args
                error = copyin(uap->buffer, &flow_ifnet_stats, uap->buffer_size);
                if (error) {
                        NECPLOG(LOG_ERR, "necp_client_remove flow_ifnet_stats copyin error (%d)", error);
-                       // Not fatal
+                       // Not fatal; make sure to zero-out stats in case of partial copy
+                       memset(&flow_ifnet_stats, 0, sizeof(flow_ifnet_stats));
+                       error = 0;
                }
        } else if (uap->buffer != 0) {
                NECPLOG(LOG_ERR, "necp_client_remove unexpected parameters length (%zu)", uap->buffer_size);
        }
 
-       struct _necp_client_tree clients_to_close;
-       RB_INIT(&clients_to_close);
        NECP_FD_LOCK(fd_data);
+
        pid_t pid = fd_data->proc_pid;
-       RB_FOREACH_SAFE(client, _necp_client_tree, &fd_data->clients, temp_client) {
-               if (uuid_compare(client->client_id, client_id) == 0) {
-                       NECP_CLIENT_TREE_LOCK_EXCLUSIVE();
-                       RB_REMOVE(_necp_client_global_tree, &necp_client_global_tree, client);
-                       NECP_CLIENT_TREE_UNLOCK();
-                       RB_REMOVE(_necp_client_tree, &fd_data->clients, client);
-                       RB_INSERT(_necp_client_tree, &clients_to_close, client);
+       struct necp_client *client = necp_client_fd_find_client_unlocked(fd_data, client_id);
+       if (client != NULL) {
+               // Remove any flow registrations that match
+               struct necp_client_flow_registration *flow_registration = NULL;
+               struct necp_client_flow_registration *temp_flow_registration = NULL;
+               RB_FOREACH_SAFE(flow_registration, _necp_fd_flow_tree, &fd_data->flows, temp_flow_registration) {
+                       if (flow_registration->client == client) {
+                               NECP_FLOW_TREE_LOCK_EXCLUSIVE();
+                               RB_REMOVE(_necp_client_flow_global_tree, &necp_client_flow_global_tree, flow_registration);
+                               NECP_FLOW_TREE_UNLOCK();
+                               RB_REMOVE(_necp_fd_flow_tree, &fd_data->flows, flow_registration);
+                       }
                }
+               // Remove client from lists
+               NECP_CLIENT_TREE_LOCK_EXCLUSIVE();
+               RB_REMOVE(_necp_client_global_tree, &necp_client_global_tree, client);
+               NECP_CLIENT_TREE_UNLOCK();
+               RB_REMOVE(_necp_client_tree, &fd_data->clients, client);
        }
 
 
        NECP_FD_UNLOCK(fd_data);
 
-       RB_FOREACH_SAFE(client, _necp_client_tree, &clients_to_close, temp_client) {
-               RB_REMOVE(_necp_client_tree, &clients_to_close, client);
+       if (client != NULL) {
+               ASSERT(error == 0);
                necp_destroy_client(client, pid, true);
+       } else {
+               error = ENOENT;
+               NECPLOG(LOG_ERR, "necp_client_remove invalid client_id (%d)", error);
        }
 done:
        *retval = error;
 
-       return (error);
+       return error;
 }
 
-static int
+
+// Don't inline the function since it includes necp_client_parsed_parameters on the stack
+static __attribute__((noinline)) int
 necp_client_check_tcp_heuristics(struct necp_client *client, struct necp_client_flow *flow, u_int32_t *flags, u_int8_t *tfo_cookie, u_int8_t *tfo_cookie_len)
 {
        struct necp_client_parsed_parameters parsed_parameters;
        int error = 0;
 
        error = necp_client_parse_parameters(client->parameters,
-                                           (u_int32_t)client->parameters_length,
-                                           &parsed_parameters);
+           (u_int32_t)client->parameters_length,
+           &parsed_parameters);
        if (error) {
                NECPLOG(LOG_ERR, "necp_client_parse_parameters error (%d)", error);
-               return (error);
+               return error;
        }
 
        if ((flow->remote_addr.sa.sa_family != AF_INET &&
-                flow->remote_addr.sa.sa_family != AF_INET6) ||
-               (flow->local_addr.sa.sa_family != AF_INET &&
-                flow->local_addr.sa.sa_family != AF_INET6)) {
-               return (EINVAL);
+           flow->remote_addr.sa.sa_family != AF_INET6) ||
+           (flow->local_addr.sa.sa_family != AF_INET &&
+           flow->local_addr.sa.sa_family != AF_INET6)) {
+               return EINVAL;
        }
 
        NECP_CLIENT_ROUTE_LOCK(client);
 
        if (client->current_route == NULL) {
-           error = ENOENT;
-           goto do_unlock;
+               error = ENOENT;
+               goto do_unlock;
        }
 
        bool check_ecn = false;
        do {
                if ((parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_ECN_ENABLE) ==
-                       NECP_CLIENT_PARAMETER_FLAG_ECN_ENABLE) {
+                   NECP_CLIENT_PARAMETER_FLAG_ECN_ENABLE) {
                        check_ecn = true;
                        break;
                }
 
                if ((parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_ECN_DISABLE) ==
-                       NECP_CLIENT_PARAMETER_FLAG_ECN_DISABLE) {
+                   NECP_CLIENT_PARAMETER_FLAG_ECN_DISABLE) {
                        break;
                }
 
@@ -3412,25 +4838,24 @@ necp_client_check_tcp_heuristics(struct necp_client *client, struct necp_client_
 
                bool inbound = ((parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) == 0);
                if ((inbound && tcp_ecn_inbound == 1) ||
-                       (!inbound && tcp_ecn_outbound == 1)) {
+                   (!inbound && tcp_ecn_outbound == 1)) {
                        check_ecn = true;
                }
        } while (false);
 
        if (check_ecn) {
                if (tcp_heuristic_do_ecn_with_address(client->current_route->rt_ifp,
-                                                       (union sockaddr_in_4_6 *)&flow->local_addr)) {
+                   (union sockaddr_in_4_6 *)&flow->local_addr)) {
                        *flags |= NECP_CLIENT_RESULT_FLAG_ECN_ENABLED;
                }
        }
 
        if ((parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_TFO_ENABLE) ==
-               NECP_CLIENT_PARAMETER_FLAG_TFO_ENABLE) {
-
+           NECP_CLIENT_PARAMETER_FLAG_TFO_ENABLE) {
                if (!tcp_heuristic_do_tfo_with_address(client->current_route->rt_ifp,
-                                                       (union sockaddr_in_4_6 *)&flow->local_addr,
-                                                       (union sockaddr_in_4_6 *)&flow->remote_addr,
-                                                       tfo_cookie, tfo_cookie_len)) {
+                   (union sockaddr_in_4_6 *)&flow->local_addr,
+                   (union sockaddr_in_4_6 *)&flow->remote_addr,
+                   tfo_cookie, tfo_cookie_len)) {
                        *flags |= NECP_CLIENT_RESULT_FLAG_FAST_OPEN_BLOCKED;
                        *tfo_cookie_len = 0;
                }
@@ -3441,191 +4866,281 @@ necp_client_check_tcp_heuristics(struct necp_client *client, struct necp_client_
 do_unlock:
        NECP_CLIENT_ROUTE_UNLOCK(client);
 
-       return (error);
+       return error;
+}
+
+static size_t
+necp_client_calculate_flow_tlv_size(struct necp_client_flow_registration *flow_registration)
+{
+       size_t assigned_results_size = 0;
+       struct necp_client_flow *flow = NULL;
+       LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
+               if (flow->assigned) {
+                       size_t header_length = 0;
+                       if (flow->nexus) {
+                               header_length = sizeof(struct necp_client_nexus_flow_header);
+                       } else {
+                               header_length = sizeof(struct necp_client_flow_header);
+                       }
+                       assigned_results_size += (header_length + flow->assigned_results_length);
+
+                       if (flow->has_protoctl_event) {
+                               assigned_results_size += sizeof(struct necp_client_flow_protoctl_event_header);
+                       }
+               }
+       }
+       return assigned_results_size;
+}
+
+static int
+necp_client_fillout_flow_tlvs(struct necp_client *client,
+    bool client_is_observed,
+    struct necp_client_flow_registration *flow_registration,
+    struct necp_client_action_args *uap,
+    size_t *assigned_results_cursor)
+{
+       int error = 0;
+       struct necp_client_flow *flow = NULL;
+       LIST_FOREACH(flow, &flow_registration->flow_list, flow_chain) {
+               if (flow->assigned) {
+                       // Write TLV headers
+                       struct necp_client_nexus_flow_header header = {};
+                       u_int32_t length = 0;
+                       u_int32_t flags = 0;
+                       u_int8_t tfo_cookie_len = 0;
+                       u_int8_t type = 0;
+
+                       type = NECP_CLIENT_RESULT_FLOW_ID;
+                       length = sizeof(header.flow_header.flow_id);
+                       memcpy(&header.flow_header.flow_id_tlv_header.type, &type, sizeof(type));
+                       memcpy(&header.flow_header.flow_id_tlv_header.length, &length, sizeof(length));
+                       uuid_copy(header.flow_header.flow_id, flow_registration->registration_id);
+
+                       if (flow->nexus) {
+                               if (flow->check_tcp_heuristics) {
+                                       u_int8_t tfo_cookie[NECP_TFO_COOKIE_LEN_MAX];
+                                       tfo_cookie_len = NECP_TFO_COOKIE_LEN_MAX;
+
+                                       if (necp_client_check_tcp_heuristics(client, flow, &flags,
+                                           tfo_cookie, &tfo_cookie_len) != 0) {
+                                               tfo_cookie_len = 0;
+                                       } else {
+                                               flow->check_tcp_heuristics = FALSE;
+
+                                               if (tfo_cookie_len != 0) {
+                                                       type = NECP_CLIENT_RESULT_TFO_COOKIE;
+                                                       length = tfo_cookie_len;
+                                                       memcpy(&header.tfo_cookie_tlv_header.type, &type, sizeof(type));
+                                                       memcpy(&header.tfo_cookie_tlv_header.length, &length, sizeof(length));
+                                                       memcpy(&header.tfo_cookie_value, tfo_cookie, tfo_cookie_len);
+                                               }
+                                       }
+                               }
+                       }
+
+                       size_t header_length = 0;
+                       if (flow->nexus) {
+                               if (tfo_cookie_len != 0) {
+                                       header_length = sizeof(struct necp_client_nexus_flow_header) - (NECP_TFO_COOKIE_LEN_MAX - tfo_cookie_len);
+                               } else {
+                                       header_length = sizeof(struct necp_client_nexus_flow_header) - sizeof(struct necp_tlv_header) - NECP_TFO_COOKIE_LEN_MAX;
+                               }
+                       } else {
+                               header_length = sizeof(struct necp_client_flow_header);
+                       }
+
+                       type = NECP_CLIENT_RESULT_FLAGS;
+                       length = sizeof(header.flow_header.flags_value);
+                       memcpy(&header.flow_header.flags_tlv_header.type, &type, sizeof(type));
+                       memcpy(&header.flow_header.flags_tlv_header.length, &length, sizeof(length));
+                       if (flow->assigned) {
+                               flags |= NECP_CLIENT_RESULT_FLAG_FLOW_ASSIGNED;
+                       }
+                       if (flow->viable) {
+                               flags |= NECP_CLIENT_RESULT_FLAG_FLOW_VIABLE;
+                       }
+                       if (flow_registration->defunct) {
+                               flags |= NECP_CLIENT_RESULT_FLAG_DEFUNCT;
+                       }
+                       flags |= flow->necp_flow_flags;
+                       memcpy(&header.flow_header.flags_value, &flags, sizeof(flags));
+
+                       type = NECP_CLIENT_RESULT_INTERFACE;
+                       length = sizeof(header.flow_header.interface_value);
+                       memcpy(&header.flow_header.interface_tlv_header.type, &type, sizeof(type));
+                       memcpy(&header.flow_header.interface_tlv_header.length, &length, sizeof(length));
+
+                       struct necp_client_result_interface interface_struct;
+                       interface_struct.generation = 0;
+                       interface_struct.index = flow->interface_index;
+
+                       memcpy(&header.flow_header.interface_value, &interface_struct, sizeof(interface_struct));
+                       if (flow->nexus) {
+                               type = NECP_CLIENT_RESULT_NETAGENT;
+                               length = sizeof(header.agent_value);
+                               memcpy(&header.agent_tlv_header.type, &type, sizeof(type));
+                               memcpy(&header.agent_tlv_header.length, &length, sizeof(length));
+
+                               struct necp_client_result_netagent agent_struct;
+                               agent_struct.generation = 0;
+                               uuid_copy(agent_struct.netagent_uuid, flow->u.nexus_agent);
+
+                               memcpy(&header.agent_value, &agent_struct, sizeof(agent_struct));
+                       }
+
+                       // Don't include outer TLV header in length field
+                       type = NECP_CLIENT_RESULT_FLOW;
+                       length = (header_length - sizeof(struct necp_tlv_header) + flow->assigned_results_length);
+                       if (flow->has_protoctl_event) {
+                               length += sizeof(struct necp_client_flow_protoctl_event_header);
+                       }
+                       memcpy(&header.flow_header.outer_header.type, &type, sizeof(type));
+                       memcpy(&header.flow_header.outer_header.length, &length, sizeof(length));
+
+                       error = copyout(&header, uap->buffer + client->result_length + *assigned_results_cursor, header_length);
+                       if (error) {
+                               NECPLOG(LOG_ERR, "necp_client_copy assigned results tlv_header copyout error (%d)", error);
+                               return error;
+                       }
+                       *assigned_results_cursor += header_length;
+
+                       if (flow->assigned_results && flow->assigned_results_length) {
+                               // Write inner TLVs
+                               error = copyout(flow->assigned_results, uap->buffer + client->result_length + *assigned_results_cursor,
+                                   flow->assigned_results_length);
+                               if (error) {
+                                       NECPLOG(LOG_ERR, "necp_client_copy assigned results copyout error (%d)", error);
+                                       return error;
+                               }
+                       }
+                       *assigned_results_cursor += flow->assigned_results_length;
+
+                       /* Read the protocol event and reset it */
+                       if (flow->has_protoctl_event) {
+                               struct necp_client_flow_protoctl_event_header protoctl_event_header = {};
+
+                               type = NECP_CLIENT_RESULT_PROTO_CTL_EVENT;
+                               length = sizeof(protoctl_event_header.protoctl_event);
+
+                               memcpy(&protoctl_event_header.protoctl_tlv_header.type, &type, sizeof(type));
+                               memcpy(&protoctl_event_header.protoctl_tlv_header.length, &length, sizeof(length));
+                               memcpy(&protoctl_event_header.protoctl_event, &flow->protoctl_event,
+                                   sizeof(flow->protoctl_event));
+
+                               error = copyout(&protoctl_event_header, uap->buffer + client->result_length + *assigned_results_cursor,
+                                   sizeof(protoctl_event_header));
+
+                               if (error) {
+                                       NECPLOG(LOG_ERR, "necp_client_copy protocol control event results"
+                                           " tlv_header copyout error (%d)", error);
+                                       return error;
+                               }
+                               *assigned_results_cursor += sizeof(protoctl_event_header);
+                               flow->has_protoctl_event = FALSE;
+                               flow->protoctl_event.protoctl_event_code = 0;
+                               flow->protoctl_event.protoctl_event_val = 0;
+                               flow->protoctl_event.protoctl_event_tcp_seq_num = 0;
+                       }
+               }
+       }
+       if (!client_is_observed) {
+               flow_registration->flow_result_read = TRUE;
+       }
+       return 0;
 }
 
 static int
-necp_client_copy_internal(struct necp_client *client, bool client_is_observed, struct necp_client_action_args *uap, int *retval)
+necp_client_copy_internal(struct necp_client *client, uuid_t client_id, bool client_is_observed, struct necp_client_action_args *uap, int *retval)
 {
+       NECP_CLIENT_ASSERT_LOCKED(client);
        int error = 0;
        // Copy results out
        if (uap->action == NECP_CLIENT_ACTION_COPY_PARAMETERS) {
                if (uap->buffer_size < client->parameters_length) {
-                       error = EINVAL;
-                       goto done;
+                       return EINVAL;
                }
                error = copyout(client->parameters, uap->buffer, client->parameters_length);
                if (error) {
                        NECPLOG(LOG_ERR, "necp_client_copy parameters copyout error (%d)", error);
-                       goto done;
+                       return error;
                }
                *retval = client->parameters_length;
        } else if (uap->action == NECP_CLIENT_ACTION_COPY_UPDATED_RESULT &&
-                          client->result_read && client->flow_result_read) {
+           client->result_read && !necp_client_has_unread_flows(client)) {
                // Copy updates only, but nothing to read
                // Just return 0 for bytes read
                *retval = 0;
        } else if (uap->action == NECP_CLIENT_ACTION_COPY_RESULT ||
-                          uap->action == NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) {
+           uap->action == NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) {
                size_t assigned_results_size = 0;
-               struct necp_client_flow *flow = NULL;
-               LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-                       if (flow->nexus || (flow->socket && flow->assigned)) {
-                               size_t header_length = 0;
-                               if (flow->nexus) {
-                                       header_length = sizeof(struct necp_client_nexus_flow_header);
-                               } else {
-                                       header_length = sizeof(struct necp_client_flow_header);
-                               }
-                               assigned_results_size += (header_length + flow->assigned_results_length);
 
-                               if (flow->has_protoctl_event) {
-                                       assigned_results_size += sizeof(struct necp_client_flow_protoctl_event_header);
+               bool some_flow_is_defunct = false;
+               struct necp_client_flow_registration *single_flow_registration = NULL;
+               if (necp_client_id_is_flow(client_id)) {
+                       single_flow_registration = necp_client_find_flow(client, client_id);
+                       if (single_flow_registration != NULL) {
+                               assigned_results_size += necp_client_calculate_flow_tlv_size(single_flow_registration);
+                       }
+               } else {
+                       // This request is for the client, so copy everything
+                       struct necp_client_flow_registration *flow_registration = NULL;
+                       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+                               if (flow_registration->defunct) {
+                                       some_flow_is_defunct = true;
                                }
+                               assigned_results_size += necp_client_calculate_flow_tlv_size(flow_registration);
                        }
                }
                if (uap->buffer_size < (client->result_length + assigned_results_size)) {
-                       error = EINVAL;
-                       goto done;
-               }
-               error = copyout(client->result, uap->buffer, client->result_length);
-               if (error) {
-                       NECPLOG(LOG_ERR, "necp_client_copy result copyout error (%d)", error);
-                       goto done;
+                       return EINVAL;
+               }
+
+               u_int32_t original_flags = 0;
+               bool flags_updated = false;
+               if (some_flow_is_defunct && client->legacy_client_is_flow) {
+                       // If our client expects the defunct flag in the client, add it now
+                       u_int32_t client_flags = 0;
+                       u_int32_t value_size = 0;
+                       u_int8_t *flags_pointer = necp_buffer_get_tlv_value(client->result, 0, &value_size);
+                       if (flags_pointer != NULL && value_size == sizeof(client_flags)) {
+                               memcpy(&client_flags, flags_pointer, value_size);
+                               original_flags = client_flags;
+                               client_flags |= NECP_CLIENT_RESULT_FLAG_DEFUNCT;
+                               (void)necp_buffer_write_tlv_if_different(client->result, NECP_CLIENT_RESULT_FLAGS,
+                                   sizeof(client_flags), &client_flags, &flags_updated,
+                                   client->result, sizeof(client->result));
+                       }
                }
 
-               size_t assigned_results_cursor = 0;
-
-               flow = NULL;
-               LIST_FOREACH(flow, &client->flow_list, flow_chain) {
-                       if (flow->nexus || (flow->socket && flow->assigned)) {
-                               // Write TLV headers
-                               struct necp_client_nexus_flow_header header = {};
-                               u_int32_t length = 0;
-                               u_int32_t flags = 0;
-                               u_int8_t tfo_cookie_len = 0;
-                               u_int8_t type = 0;
-
-                               if (flow->nexus) {
-                                       if (flow->check_tcp_heuristics) {
-                                               u_int8_t tfo_cookie[NECP_TFO_COOKIE_LEN_MAX];
-                                               tfo_cookie_len = NECP_TFO_COOKIE_LEN_MAX;
-
-                                               if (necp_client_check_tcp_heuristics(client, flow, &flags,
-                                                                                   tfo_cookie, &tfo_cookie_len) != 0) {
-                                                       tfo_cookie_len = 0;
-                                               } else {
-                                                       flow->check_tcp_heuristics = FALSE;
-
-                                                       if (tfo_cookie_len != 0) {
-                                                               type = NECP_CLIENT_RESULT_TFO_COOKIE;
-                                                               length = tfo_cookie_len;
-                                                               memcpy(&header.tfo_cookie_tlv_header.type, &type, sizeof(type));
-                                                               memcpy(&header.tfo_cookie_tlv_header.length, &length, sizeof(length));
-                                                               memcpy(&header.tfo_cookie_value, tfo_cookie, tfo_cookie_len);
-                                                       }
-                                               }
-                                       }
-                               }
-
-                               size_t header_length = 0;
-                               if (flow->nexus) {
-                                       if (tfo_cookie_len != 0) {
-                                               header_length = sizeof(struct necp_client_nexus_flow_header) - (NECP_TFO_COOKIE_LEN_MAX - tfo_cookie_len);
-                                       } else {
-                                               header_length = sizeof(struct necp_client_nexus_flow_header) - sizeof(struct necp_tlv_header) - NECP_TFO_COOKIE_LEN_MAX;
-                                       }
-                               } else {
-                                       header_length = sizeof(struct necp_client_flow_header);
-                               }
-
-                               type = NECP_CLIENT_RESULT_FLAGS;
-                               length = sizeof(header.flow_header.flags_value);
-                               memcpy(&header.flow_header.flags_tlv_header.type, &type, sizeof(type));
-                               memcpy(&header.flow_header.flags_tlv_header.length, &length, sizeof(length));
-                               if (flow->assigned) {
-                                       flags |= NECP_CLIENT_RESULT_FLAG_FLOW_ASSIGNED;
-                               }
-                               if (flow->viable) {
-                                       flags |= NECP_CLIENT_RESULT_FLAG_FLOW_VIABLE;
-                               }
-                               memcpy(&header.flow_header.flags_value, &flags, sizeof(flags));
-
-                               type = NECP_CLIENT_RESULT_INTERFACE;
-                               length = sizeof(header.flow_header.interface_value);
-                               memcpy(&header.flow_header.interface_tlv_header.type, &type, sizeof(type));
-                               memcpy(&header.flow_header.interface_tlv_header.length, &length, sizeof(length));
-
-                               struct necp_client_result_interface interface_struct;
-                               interface_struct.generation = 0;
-                               interface_struct.index = flow->interface_index;
-
-                               memcpy(&header.flow_header.interface_value, &interface_struct, sizeof(interface_struct));
-                               if (flow->nexus) {
-                                       type = NECP_CLIENT_RESULT_NETAGENT;
-                                       length = sizeof(header.agent_value);
-                                       memcpy(&header.agent_tlv_header.type, &type, sizeof(type));
-                                       memcpy(&header.agent_tlv_header.length, &length, sizeof(length));
-
-                                       struct necp_client_result_netagent agent_struct;
-                                       agent_struct.generation = 0;
-                                       uuid_copy(agent_struct.netagent_uuid, flow->u.nexus_agent);
-
-                                       memcpy(&header.agent_value, &agent_struct, sizeof(agent_struct));
-                               }
-
-                               // Don't include outer TLV header in length field
-                               type = NECP_CLIENT_RESULT_FLOW;
-                               length = (header_length - sizeof(struct necp_tlv_header) + flow->assigned_results_length);
-                               if (flow->has_protoctl_event) {
-                                       length += sizeof(struct necp_client_flow_protoctl_event_header);
-                               }
-                               memcpy(&header.flow_header.outer_header.type, &type, sizeof(type));
-                               memcpy(&header.flow_header.outer_header.length, &length, sizeof(length));
-
-                               error = copyout(&header, uap->buffer + client->result_length + assigned_results_cursor, header_length);
-                               if (error) {
-                                       NECPLOG(LOG_ERR, "necp_client_copy assigned results tlv_header copyout error (%d)", error);
-                                       goto done;
-                               }
-                               assigned_results_cursor += header_length;
-
-                               if (flow->assigned_results && flow->assigned_results_length) {
-                                       // Write inner TLVs
-                                       error = copyout(flow->assigned_results, uap->buffer + client->result_length + assigned_results_cursor,
-                                                                       flow->assigned_results_length);
-                                       if (error) {
-                                               NECPLOG(LOG_ERR, "necp_client_copy assigned results copyout error (%d)", error);
-                                               goto done;
-                                       }
-                               }
-                               assigned_results_cursor += flow->assigned_results_length;
-
-                               /* Read the protocol event and reset it */
-                               if (flow->has_protoctl_event) {
-                                       struct necp_client_flow_protoctl_event_header protoctl_event_header = {};
-
-                                       type = NECP_CLIENT_RESULT_PROTO_CTL_EVENT;
-                                       length = sizeof(protoctl_event_header.protoctl_event);
+               error = copyout(client->result, uap->buffer, client->result_length);
 
-                                       memcpy(&protoctl_event_header.protoctl_tlv_header.type, &type, sizeof(type));
-                                       memcpy(&protoctl_event_header.protoctl_tlv_header.length, &length, sizeof(length));
-                                       memcpy(&protoctl_event_header.protoctl_event, &flow->protoctl_event,
-                                           sizeof(flow->protoctl_event));
+               if (flags_updated) {
+                       // Revert stored flags
+                       (void)necp_buffer_write_tlv_if_different(client->result, NECP_CLIENT_RESULT_FLAGS,
+                           sizeof(original_flags), &original_flags, &flags_updated,
+                           client->result, sizeof(client->result));
+               }
 
-                                       error = copyout(&protoctl_event_header, uap->buffer + client->result_length + assigned_results_cursor,
-                                           sizeof(protoctl_event_header));
+               if (error) {
+                       NECPLOG(LOG_ERR, "necp_client_copy result copyout error (%d)", error);
+                       return error;
+               }
 
-                                       if (error) {
-                                               NECPLOG(LOG_ERR, "necp_client_copy protocol control event results"
-                                                   " tlv_header copyout error (%d)", error);
-                                               goto done;
-                                       }
-                                       assigned_results_cursor += sizeof(protoctl_event_header);
-                                       flow->has_protoctl_event = FALSE;
-                                       flow->protoctl_event.protoctl_event_code = 0;
-                                       flow->protoctl_event.protoctl_event_val = 0;
-                                       flow->protoctl_event.protoctl_event_tcp_seq_num = 0;
+               size_t assigned_results_cursor = 0;
+               if (necp_client_id_is_flow(client_id)) {
+                       if (single_flow_registration != NULL) {
+                               error = necp_client_fillout_flow_tlvs(client, client_is_observed, single_flow_registration, uap, &assigned_results_cursor);
+                               if (error != 0) {
+                                       return error;
+                               }
+                       }
+               } else {
+                       // This request is for the client, so copy everything
+                       struct necp_client_flow_registration *flow_registration = NULL;
+                       RB_FOREACH(flow_registration, _necp_client_flow_tree, &client->flow_registrations) {
+                               error = necp_client_fillout_flow_tlvs(client, client_is_observed, flow_registration, uap, &assigned_results_cursor);
+                               if (error != 0) {
+                                       return error;
                                }
                        }
                }
@@ -3634,19 +5149,16 @@ necp_client_copy_internal(struct necp_client *client, bool client_is_observed, s
 
                if (!client_is_observed) {
                        client->result_read = TRUE;
-                       client->flow_result_read = TRUE;
                }
        }
 
-done:
-       return (error);
+       return 0;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_copy(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
-       struct necp_client *find_client = NULL;
        struct necp_client *client = NULL;
        uuid_t client_id;
        uuid_clear(client_id);
@@ -3654,53 +5166,56 @@ necp_client_copy(struct necp_fd_data *fd_data, struct necp_client_action_args *u
        *retval = 0;
 
        if (uap->buffer_size == 0 || uap->buffer == 0) {
-               error = EINVAL;
-               goto done;
+               return EINVAL;
        }
 
        if (uap->action != NECP_CLIENT_ACTION_COPY_PARAMETERS &&
-               uap->action != NECP_CLIENT_ACTION_COPY_RESULT &&
-               uap->action != NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) {
-               error = EINVAL;
-               goto done;
+           uap->action != NECP_CLIENT_ACTION_COPY_RESULT &&
+           uap->action != NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) {
+               return EINVAL;
        }
 
        if (uap->client_id) {
                if (uap->client_id_len != sizeof(uuid_t)) {
                        NECPLOG(LOG_ERR, "Incorrect length (got %d, expected %d)", uap->client_id_len, sizeof(uuid_t));
-                       error = ERANGE;
-                       goto done;
+                       return ERANGE;
                }
 
                error = copyin(uap->client_id, client_id, sizeof(uuid_t));
                if (error) {
                        NECPLOG(LOG_ERR, "necp_client_copy client_id copyin error (%d)", error);
-                       goto done;
+                       return error;
                }
        }
 
+       const bool is_wildcard = (bool)uuid_is_null(client_id);
+
        NECP_FD_LOCK(fd_data);
-       RB_FOREACH(find_client, _necp_client_tree, &fd_data->clients) {
-               NECP_CLIENT_LOCK(find_client);
-               if ((uap->action == NECP_CLIENT_ACTION_COPY_RESULT || uap->action == NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) &&
-                       uuid_is_null(client_id)) {
-                       if (!find_client->result_read || !find_client->flow_result_read) {
-                               client = find_client;
+
+       if (is_wildcard) {
+               if (uap->action == NECP_CLIENT_ACTION_COPY_RESULT || uap->action == NECP_CLIENT_ACTION_COPY_UPDATED_RESULT) {
+                       struct necp_client *find_client = NULL;
+                       RB_FOREACH(find_client, _necp_client_tree, &fd_data->clients) {
+                               NECP_CLIENT_LOCK(find_client);
+                               if (!find_client->result_read || necp_client_has_unread_flows(find_client)) {
+                                       client = find_client;
+                                       // Leave the client locked, and break
+                                       break;
+                               }
+                               NECP_CLIENT_UNLOCK(find_client);
                        }
-               } else if (uuid_compare(find_client->client_id, client_id) == 0) {
-                       client = find_client;
-               }
-               NECP_CLIENT_UNLOCK(find_client);
-               if (client != NULL) {
-                       break;
                }
+       } else {
+               client = necp_client_fd_find_client_and_lock(fd_data, client_id);
        }
 
        if (client != NULL) {
-               error = necp_client_copy_internal(client, FALSE, uap, retval);
+               // If client is set, it is locked
+               error = necp_client_copy_internal(client, client_id, FALSE, uap, retval);
+               NECP_CLIENT_UNLOCK(client);
        }
 
-       // Unlock our own client before moving on or returning
+       // Unlock our own fd before moving on or returning
        NECP_FD_UNLOCK(fd_data);
 
        if (client == NULL) {
@@ -3712,16 +5227,11 @@ necp_client_copy(struct necp_fd_data *fd_data, struct necp_client_action_args *u
 
                        bool found_client = FALSE;
 
-                       struct necp_client find;
-                       uuid_copy(find.client_id, client_id);
-                       client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
+                       client = necp_find_client_and_lock(client_id);
                        if (client != NULL) {
-                               NECP_CLIENT_LOCK(client);
-
                                // Matched, copy out data
                                found_client = TRUE;
-                               error = necp_client_copy_internal(client, TRUE, uap, retval);
-
+                               error = necp_client_copy_internal(client, client_id, TRUE, uap, retval);
                                NECP_CLIENT_UNLOCK(client);
                        }
 
@@ -3730,21 +5240,18 @@ necp_client_copy(struct necp_fd_data *fd_data, struct necp_client_action_args *u
 
                        // No client found, fail
                        if (!found_client) {
-                               error = ENOENT;
-                               goto done;
+                               return ENOENT;
                        }
                } else {
                        // No client found, and not allowed to search other fds, fail
-                       error = ENOENT;
-                       goto done;
+                       return ENOENT;
                }
        }
 
-done:
-       return (error);
+       return error;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_copy_client_update(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -3753,17 +5260,17 @@ necp_client_copy_client_update(struct necp_fd_data *fd_data, struct necp_client_
 
        if (!(fd_data->flags & NECP_OPEN_FLAG_PUSH_OBSERVER)) {
                NECPLOG0(LOG_ERR, "NECP fd is not observer, cannot copy client update");
-               return (EINVAL);
+               return EINVAL;
        }
 
        if (uap->client_id_len != sizeof(uuid_t) || uap->client_id == 0) {
                NECPLOG0(LOG_ERR, "Client id invalid, cannot copy client update");
-               return (EINVAL);
+               return EINVAL;
        }
 
        if (uap->buffer_size == 0 || uap->buffer == 0) {
                NECPLOG0(LOG_ERR, "Buffer invalid, cannot copy client update");
-               return (EINVAL);
+               return EINVAL;
        }
 
        NECP_FD_LOCK(fd_data);
@@ -3799,11 +5306,12 @@ necp_client_copy_client_update(struct necp_fd_data *fd_data, struct necp_client_
                error = ENOENT;
        }
 
-       return (error);
+       return error;
 }
 
 static int
-necp_client_copy_parameters_locked(struct necp_client *client, struct necp_client_nexus_parameters *parameters)
+necp_client_copy_parameters_locked(struct necp_client *client,
+    struct necp_client_nexus_parameters *parameters)
 {
        VERIFY(parameters != NULL);
 
@@ -3819,9 +5327,21 @@ necp_client_copy_parameters_locked(struct necp_client *client, struct necp_clien
        memcpy(&parameters->local_addr, &parsed_parameters.local_addr, sizeof(parameters->local_addr));
        memcpy(&parameters->remote_addr, &parsed_parameters.remote_addr, sizeof(parameters->remote_addr));
        parameters->ip_protocol = parsed_parameters.ip_protocol;
+       if (parsed_parameters.valid_fields & NECP_PARSED_PARAMETERS_FIELD_TRANSPORT_PROTOCOL) {
+               parameters->transport_protocol = parsed_parameters.transport_protocol;
+       } else {
+               parameters->transport_protocol = parsed_parameters.ip_protocol;
+       }
+       parameters->ethertype = parsed_parameters.ethertype;
        parameters->traffic_class = parsed_parameters.traffic_class;
-       uuid_copy(parameters->euuid, parsed_parameters.effective_uuid);
+       if (uuid_is_null(client->override_euuid)) {
+               uuid_copy(parameters->euuid, parsed_parameters.effective_uuid);
+       } else {
+               uuid_copy(parameters->euuid, client->override_euuid);
+       }
        parameters->is_listener = (parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_LISTENER) ? 1 : 0;
+       parameters->is_interpose = (parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_INTERPOSE) ? 1 : 0;
+       parameters->is_custom_ether = (parsed_parameters.flags & NECP_CLIENT_PARAMETER_FLAG_CUSTOM_ETHER) ? 1 : 0;
        parameters->policy_id = client->policy_id;
 
        // parse client result flag
@@ -3834,48 +5354,24 @@ necp_client_copy_parameters_locked(struct necp_client *client, struct necp_clien
        }
        parameters->allow_qos_marking = (client_result_flags & NECP_CLIENT_RESULT_FLAG_ALLOW_QOS_MARKING) ? 1 : 0;
 
-       return (error);
-}
-
-int
-necp_client_copy_parameters(uuid_t client_id, struct necp_client_nexus_parameters *parameters)
-{
-       int error = 0;
-       struct necp_client *client = NULL;
-
-       if (parameters == NULL) {
-               return EINVAL;
-       }
-
-       // Lock tree
-       NECP_CLIENT_TREE_LOCK_SHARED();
-
-       bool found_client = FALSE;
-       struct necp_client find;
-       uuid_copy(find.client_id, client_id);
-       client = RB_FIND(_necp_client_global_tree, &necp_client_global_tree, &find);
-       if (client != NULL) {
-               NECP_CLIENT_LOCK(client);
-
-               // Matched, parse parameters
-               found_client = TRUE;
-               error = necp_client_copy_parameters_locked(client, parameters);
-
-               NECP_CLIENT_UNLOCK(client);
-       }
-
-       // Unlock tree
-       NECP_CLIENT_TREE_UNLOCK();
-
-       // No client found, fail
-       if (!found_client) {
-               return ENOENT;
+       if (parsed_parameters.valid_fields & NECP_PARSED_PARAMETERS_FIELD_LOCAL_ADDR_PREFERENCE) {
+               if (parsed_parameters.local_address_preference == NECP_CLIENT_PARAMETER_LOCAL_ADDRESS_PREFERENCE_DEFAULT) {
+                       parameters->override_address_selection = false;
+               } else if (parsed_parameters.local_address_preference == NECP_CLIENT_PARAMETER_LOCAL_ADDRESS_PREFERENCE_TEMPORARY) {
+                       parameters->override_address_selection = true;
+                       parameters->use_stable_address = false;
+               } else if (parsed_parameters.local_address_preference == NECP_CLIENT_PARAMETER_LOCAL_ADDRESS_PREFERENCE_STABLE) {
+                       parameters->override_address_selection = true;
+                       parameters->use_stable_address = true;
+               }
+       } else {
+               parameters->override_address_selection = false;
        }
 
        return error;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_list(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -3948,8 +5444,8 @@ necp_client_list(struct necp_fd_data *fd_data, struct necp_client_action_args *u
        }
 
        if (requested_client_count > 0 &&
-               client_count > 0 &&
-               list != NULL) {
+           client_count > 0 &&
+           list != NULL) {
                error = copyout(list, uap->buffer + sizeof(client_count), copy_buffer_size);
                if (error) {
                        NECPLOG(LOG_ERR, "necp_client_list client count copyout error (%d)", error);
@@ -3962,7 +5458,7 @@ done:
        }
        *retval = error;
 
-       return (error);
+       return error;
 }
 
 
@@ -4004,7 +5500,7 @@ necp_client_remove_assertion(struct necp_client *client, uuid_t netagent_uuid)
        return true;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_agent_action(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -4015,7 +5511,8 @@ necp_client_agent_action(struct necp_fd_data *fd_data, struct necp_client_action
        size_t parameters_size = uap->buffer_size;
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t) ||
-               uap->buffer_size == 0 || uap->buffer == 0) {
+           uap->buffer_size == 0 || uap->buffer == 0) {
+               NECPLOG0(LOG_ERR, "necp_client_agent_action invalid parameters");
                error = EINVAL;
                goto done;
        }
@@ -4026,7 +5523,14 @@ necp_client_agent_action(struct necp_fd_data *fd_data, struct necp_client_action
                goto done;
        }
 
+       if (uap->buffer_size > NECP_MAX_AGENT_ACTION_SIZE) {
+               NECPLOG(LOG_ERR, "necp_client_agent_action invalid buffer size (>%u)", NECP_MAX_AGENT_ACTION_SIZE);
+               error = EINVAL;
+               goto done;
+       }
+
        if ((parameters = _MALLOC(uap->buffer_size, M_NECP, M_WAITOK | M_ZERO)) == NULL) {
+               NECPLOG0(LOG_ERR, "necp_client_agent_action malloc failed");
                error = ENOMEM;
                goto done;
        }
@@ -4054,50 +5558,50 @@ necp_client_agent_action(struct necp_fd_data *fd_data, struct necp_client_action
                        if (length > 0) {
                                u_int8_t *value = necp_buffer_get_tlv_value(parameters, offset, NULL);
                                if (length >= sizeof(uuid_t) &&
-                                       value != NULL &&
-                                       (type == NECP_CLIENT_PARAMETER_TRIGGER_AGENT ||
-                                        type == NECP_CLIENT_PARAMETER_ASSERT_AGENT ||
-                                        type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT)) {
-
-                                               uuid_t agent_uuid;
-                                               uuid_copy(agent_uuid, value);
-                                               u_int8_t netagent_message_type = 0;
-                                               if (type == NECP_CLIENT_PARAMETER_TRIGGER_AGENT) {
-                                                       netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_TRIGGER;
-                                               } else if (type == NECP_CLIENT_PARAMETER_ASSERT_AGENT) {
-                                                       netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_ASSERT;
-                                               } else if (type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT) {
-                                                       netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
-                                               }
-
-                                               // Before unasserting, verify that the assertion was already taken
-                                               if (type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT) {
-                                                       if (!necp_client_remove_assertion(client, agent_uuid)) {
-                                                               error = ENOENT;
-                                                               break;
-                                                       }
-                                               }
+                                   value != NULL &&
+                                   (type == NECP_CLIENT_PARAMETER_TRIGGER_AGENT ||
+                                   type == NECP_CLIENT_PARAMETER_ASSERT_AGENT ||
+                                   type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT)) {
+                                       uuid_t agent_uuid;
+                                       uuid_copy(agent_uuid, value);
+                                       u_int8_t netagent_message_type = 0;
+                                       if (type == NECP_CLIENT_PARAMETER_TRIGGER_AGENT) {
+                                               netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_TRIGGER;
+                                       } else if (type == NECP_CLIENT_PARAMETER_ASSERT_AGENT) {
+                                               netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_ASSERT;
+                                       } else if (type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT) {
+                                               netagent_message_type = NETAGENT_MESSAGE_TYPE_CLIENT_UNASSERT;
+                                       }
 
-                                               struct necp_client_nexus_parameters parsed_parameters = {};
-                                               necp_client_copy_parameters_locked(client, &parsed_parameters);
-
-                                               error = netagent_client_message_with_params(agent_uuid,
-                                                                                                                                       client_id,
-                                                                                                                                       fd_data->proc_pid,
-                                                                                                                                       netagent_message_type,
-                                                                                                                                       &parsed_parameters,
-                                                                                                                                       NULL, NULL);
-                                               if (error == 0) {
-                                                       acted_on_agent = TRUE;
-                                               } else {
+                                       // Before unasserting, verify that the assertion was already taken
+                                       if (type == NECP_CLIENT_PARAMETER_UNASSERT_AGENT) {
+                                               if (!necp_client_remove_assertion(client, agent_uuid)) {
+                                                       error = ENOENT;
                                                        break;
                                                }
+                                       }
 
-                                               // Only save the assertion if the action succeeded
-                                               if (type == NECP_CLIENT_PARAMETER_ASSERT_AGENT) {
-                                                       necp_client_add_assertion(client, agent_uuid);
-                                               }
+                                       struct necp_client_nexus_parameters parsed_parameters = {};
+                                       necp_client_copy_parameters_locked(client, &parsed_parameters);
+
+                                       error = netagent_client_message_with_params(agent_uuid,
+                                           client_id,
+                                           fd_data->proc_pid,
+                                           client->agent_handle,
+                                           netagent_message_type,
+                                           (struct necp_client_agent_parameters *)&parsed_parameters,
+                                           NULL, NULL);
+                                       if (error == 0) {
+                                               acted_on_agent = TRUE;
+                                       } else {
+                                               break;
                                        }
+
+                                       // Only save the assertion if the action succeeded
+                                       if (type == NECP_CLIENT_PARAMETER_ASSERT_AGENT) {
+                                               necp_client_add_assertion(client, agent_uuid);
+                                       }
+                               }
                        }
 
                        offset += sizeof(struct necp_tlv_header) + length;
@@ -4108,7 +5612,7 @@ necp_client_agent_action(struct necp_fd_data *fd_data, struct necp_client_action
        NECP_FD_UNLOCK(fd_data);
 
        if (!acted_on_agent &&
-               error == 0) {
+           error == 0) {
                error = ENOENT;
        }
 done:
@@ -4118,17 +5622,17 @@ done:
                parameters = NULL;
        }
 
-       return (error);
+       return error;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_copy_agent(__unused struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
        uuid_t agent_uuid;
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t) ||
-               uap->buffer_size == 0 || uap->buffer == 0) {
+           uap->buffer_size == 0 || uap->buffer == 0) {
                NECPLOG0(LOG_ERR, "necp_client_copy_agent bad input");
                error = EINVAL;
                goto done;
@@ -4148,10 +5652,10 @@ necp_client_copy_agent(__unused struct necp_fd_data *fd_data, struct necp_client
 done:
        *retval = error;
 
-       return (error);
+       return error;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_agent_use(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -4160,7 +5664,7 @@ necp_client_agent_use(struct necp_fd_data *fd_data, struct necp_client_action_ar
        struct necp_agent_use_parameters parameters;
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t) ||
-               uap->buffer_size != sizeof(parameters) || uap->buffer == 0) {
+           uap->buffer_size != sizeof(parameters) || uap->buffer == 0) {
                error = EINVAL;
                goto done;
        }
@@ -4199,18 +5703,31 @@ necp_client_agent_use(struct necp_fd_data *fd_data, struct necp_client_action_ar
 done:
        *retval = error;
 
-       return (error);
+       return error;
 }
 
-static int
+struct necp_interface_details_legacy {
+       char name[IFXNAMSIZ];
+       u_int32_t index;
+       u_int32_t generation;
+       u_int32_t functional_type;
+       u_int32_t delegate_index;
+       u_int32_t flags; // see NECP_INTERFACE_FLAG_*
+       u_int32_t mtu;
+       struct necp_interface_signature ipv4_signature;
+       struct necp_interface_signature ipv6_signature;
+};
+
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_copy_interface(__unused struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
        u_int32_t interface_index = 0;
-       struct necp_interface_details interface_details;
+       struct necp_interface_details interface_details = {};
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(u_int32_t) ||
-               uap->buffer_size < sizeof(interface_details) || uap->buffer == 0) {
+           uap->buffer_size < sizeof(struct necp_interface_details_legacy) ||
+           uap->buffer == 0) {
                NECPLOG0(LOG_ERR, "necp_client_copy_interface bad input");
                error = EINVAL;
                goto done;
@@ -4228,8 +5745,6 @@ necp_client_copy_interface(__unused struct necp_fd_data *fd_data, struct necp_cl
                goto done;
        }
 
-       memset(&interface_details, 0, sizeof(interface_details));
-
        ifnet_head_lock_shared();
        ifnet_t interface = NULL;
        if (interface_index != IFSCOPE_NONE && interface_index <= (u_int32_t)if_index) {
@@ -4249,18 +5764,30 @@ necp_client_copy_interface(__unused struct necp_fd_data *fd_data, struct necp_cl
                if (IFNET_IS_EXPENSIVE(interface)) {
                        interface_details.flags |= NECP_INTERFACE_FLAG_EXPENSIVE;
                }
+               if (IFNET_IS_CONSTRAINED(interface)) {
+                       interface_details.flags |= NECP_INTERFACE_FLAG_CONSTRAINED;
+               }
                if ((interface->if_eflags & IFEF_TXSTART) == IFEF_TXSTART) {
                        interface_details.flags |= NECP_INTERFACE_FLAG_TXSTART;
                }
                if ((interface->if_eflags & IFEF_NOACKPRI) == IFEF_NOACKPRI) {
                        interface_details.flags |= NECP_INTERFACE_FLAG_NOACKPRI;
                }
+               if ((interface->if_eflags & IFEF_3CA) == IFEF_3CA) {
+                       interface_details.flags |= NECP_INTERFACE_FLAG_3CARRIERAGG;
+               }
+               if (IFNET_IS_LOW_POWER(interface)) {
+                       interface_details.flags |= NECP_INTERFACE_FLAG_IS_LOW_POWER;
+               }
+               if (interface->if_xflags & IFXF_MPK_LOG) {
+                       interface_details.flags |= NECP_INTERFACE_FLAG_MPK_LOG;
+               }
                interface_details.mtu = interface->if_mtu;
 
                u_int8_t ipv4_signature_len = sizeof(interface_details.ipv4_signature.signature);
                u_int16_t ipv4_signature_flags;
                if (ifnet_get_netsignature(interface, AF_INET, &ipv4_signature_len, &ipv4_signature_flags,
-                                                                  (u_int8_t *)&interface_details.ipv4_signature) != 0) {
+                   (u_int8_t *)&interface_details.ipv4_signature) != 0) {
                        ipv4_signature_len = 0;
                }
                interface_details.ipv4_signature.signature_len = ipv4_signature_len;
@@ -4268,15 +5795,36 @@ necp_client_copy_interface(__unused struct necp_fd_data *fd_data, struct necp_cl
                u_int8_t ipv6_signature_len = sizeof(interface_details.ipv6_signature.signature);
                u_int16_t ipv6_signature_flags;
                if (ifnet_get_netsignature(interface, AF_INET6, &ipv6_signature_len, &ipv6_signature_flags,
-                                                                  (u_int8_t *)&interface_details.ipv6_signature) != 0) {
+                   (u_int8_t *)&interface_details.ipv6_signature) != 0) {
                        ipv6_signature_len = 0;
                }
                interface_details.ipv6_signature.signature_len = ipv6_signature_len;
+
+               ifnet_lock_shared(interface);
+               struct ifaddr *ifa = NULL;
+               TAILQ_FOREACH(ifa, &interface->if_addrhead, ifa_link) {
+                       IFA_LOCK(ifa);
+                       if (ifa->ifa_addr->sa_family == AF_INET) {
+                               interface_details.flags |= NECP_INTERFACE_FLAG_HAS_NETMASK;
+                               interface_details.ipv4_netmask = ((struct in_ifaddr *)ifa)->ia_sockmask.sin_addr.s_addr;
+                               if (interface->if_flags & IFF_BROADCAST) {
+                                       interface_details.flags |= NECP_INTERFACE_FLAG_HAS_BROADCAST;
+                                       interface_details.ipv4_broadcast = ((struct in_ifaddr *)ifa)->ia_broadaddr.sin_addr.s_addr;
+                               }
+                       }
+                       IFA_UNLOCK(ifa);
+               }
+               ifnet_lock_done(interface);
        }
 
        ifnet_head_done();
 
-       error = copyout(&interface_details, uap->buffer, sizeof(interface_details));
+       // If the client is using an older version of the struct, copy that length
+       size_t copy_length = sizeof(interface_details);
+       if (uap->buffer_size < sizeof(struct necp_interface_details_legacy)) {
+               copy_length = sizeof(struct necp_interface_details_legacy);
+       }
+       error = copyout(&interface_details, uap->buffer, copy_length);
        if (error) {
                NECPLOG(LOG_ERR, "necp_client_copy_interface copyout error (%d)", error);
                goto done;
@@ -4284,11 +5832,11 @@ necp_client_copy_interface(__unused struct necp_fd_data *fd_data, struct necp_cl
 done:
        *retval = error;
 
-       return (error);
+       return error;
 }
 
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_copy_route_statistics(__unused struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -4296,7 +5844,7 @@ necp_client_copy_route_statistics(__unused struct necp_fd_data *fd_data, struct
        uuid_t client_id;
 
        if (uap->client_id == 0 || uap->client_id_len != sizeof(uuid_t) ||
-               uap->buffer_size < sizeof(struct necp_stat_counts) || uap->buffer == 0) {
+           uap->buffer_size < sizeof(struct necp_stat_counts) || uap->buffer == 0) {
                NECPLOG0(LOG_ERR, "necp_client_copy_route_statistics bad input");
                error = EINVAL;
                goto done;
@@ -4313,21 +5861,22 @@ necp_client_copy_route_statistics(__unused struct necp_fd_data *fd_data, struct
        client = necp_client_fd_find_client_and_lock(fd_data, client_id);
        if (client != NULL) {
                NECP_CLIENT_ROUTE_LOCK(client);
-               struct nstat_counts route_stats = {};
+               struct necp_stat_counts route_stats = {};
                if (client->current_route != NULL && client->current_route->rt_stats != NULL) {
-                       struct nstat_counts     *rt_stats = client->current_route->rt_stats;
-                       atomic_get_64(route_stats.nstat_rxpackets, &rt_stats->nstat_rxpackets);
-                       atomic_get_64(route_stats.nstat_rxbytes, &rt_stats->nstat_rxbytes);
-                       atomic_get_64(route_stats.nstat_txpackets, &rt_stats->nstat_txpackets);
-                       atomic_get_64(route_stats.nstat_txbytes, &rt_stats->nstat_txbytes);
-                       route_stats.nstat_rxduplicatebytes = rt_stats->nstat_rxduplicatebytes;
-                       route_stats.nstat_rxoutoforderbytes = rt_stats->nstat_rxoutoforderbytes;
-                       route_stats.nstat_txretransmit = rt_stats->nstat_txretransmit;
-                       route_stats.nstat_connectattempts = rt_stats->nstat_connectattempts;
-                       route_stats.nstat_connectsuccesses = rt_stats->nstat_connectsuccesses;
-                       route_stats.nstat_min_rtt = rt_stats->nstat_min_rtt;
-                       route_stats.nstat_avg_rtt = rt_stats->nstat_avg_rtt;
-                       route_stats.nstat_var_rtt = rt_stats->nstat_var_rtt;
+                       struct nstat_counts     *rt_stats = client->current_route->rt_stats;
+                       atomic_get_64(route_stats.necp_stat_rxpackets, &rt_stats->nstat_rxpackets);
+                       atomic_get_64(route_stats.necp_stat_rxbytes, &rt_stats->nstat_rxbytes);
+                       atomic_get_64(route_stats.necp_stat_txpackets, &rt_stats->nstat_txpackets);
+                       atomic_get_64(route_stats.necp_stat_txbytes, &rt_stats->nstat_txbytes);
+                       route_stats.necp_stat_rxduplicatebytes = rt_stats->nstat_rxduplicatebytes;
+                       route_stats.necp_stat_rxoutoforderbytes = rt_stats->nstat_rxoutoforderbytes;
+                       route_stats.necp_stat_txretransmit = rt_stats->nstat_txretransmit;
+                       route_stats.necp_stat_connectattempts = rt_stats->nstat_connectattempts;
+                       route_stats.necp_stat_connectsuccesses = rt_stats->nstat_connectsuccesses;
+                       route_stats.necp_stat_min_rtt = rt_stats->nstat_min_rtt;
+                       route_stats.necp_stat_avg_rtt = rt_stats->nstat_avg_rtt;
+                       route_stats.necp_stat_var_rtt = rt_stats->nstat_var_rtt;
+                       route_stats.necp_stat_route_flags = client->current_route->rt_flags;
                }
 
                // Unlock before copying out
@@ -4348,10 +5897,10 @@ necp_client_copy_route_statistics(__unused struct necp_fd_data *fd_data, struct
 
 done:
        *retval = error;
-       return (error);
+       return error;
 }
 
-static int
+static NECP_CLIENT_ACTION_FUNCTION int
 necp_client_update_cache(struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
 {
        int error = 0;
@@ -4377,14 +5926,22 @@ necp_client_update_cache(struct necp_fd_data *fd_data, struct necp_client_action
                goto done;
        }
 
+       struct necp_client_flow_registration *flow_registration = necp_client_find_flow(client, client_id);
+       if (flow_registration == NULL) {
+               NECP_CLIENT_UNLOCK(client);
+               NECP_FD_UNLOCK(fd_data);
+               error = ENOENT;
+               goto done;
+       }
+
        NECP_CLIENT_ROUTE_LOCK(client);
        // This needs to be changed when TFO/ECN is supported by multiple flows
-       struct necp_client_flow *flow = LIST_FIRST(&client->flow_list);
+       struct necp_client_flow *flow = LIST_FIRST(&flow_registration->flow_list);
        if (flow == NULL ||
-               (flow->remote_addr.sa.sa_family != AF_INET &&
-                flow->remote_addr.sa.sa_family != AF_INET6) ||
-               (flow->local_addr.sa.sa_family != AF_INET &&
-                flow->local_addr.sa.sa_family != AF_INET6)) {
+           (flow->remote_addr.sa.sa_family != AF_INET &&
+           flow->remote_addr.sa.sa_family != AF_INET6) ||
+           (flow->local_addr.sa.sa_family != AF_INET &&
+           flow->local_addr.sa.sa_family != AF_INET6)) {
                error = EINVAL;
                NECPLOG(LOG_ERR, "necp_client_update_cache no flow error (%d)", error);
                goto done_unlock;
@@ -4394,7 +5951,7 @@ necp_client_update_cache(struct necp_fd_data *fd_data, struct necp_client_action
        memset(&cache_buffer, 0, sizeof(cache_buffer));
 
        if (uap->buffer_size != sizeof(necp_cache_buffer) ||
-               uap->buffer == USER_ADDR_NULL) {
+           uap->buffer == USER_ADDR_NULL) {
                error = EINVAL;
                goto done_unlock;
        }
@@ -4424,13 +5981,13 @@ necp_client_update_cache(struct necp_fd_data *fd_data, struct necp_client_action
 
                if (client->current_route != NULL && client->current_route->rt_ifp != NULL) {
                        if (!client->platform_binary) {
-                           ecn_cache_buffer.necp_tcp_ecn_heuristics_success = 0;
+                               ecn_cache_buffer.necp_tcp_ecn_heuristics_success = 0;
                        }
                        tcp_heuristics_ecn_update(&ecn_cache_buffer, client->current_route->rt_ifp,
-                                                 (union sockaddr_in_4_6 *)&flow->local_addr);
+                           (union sockaddr_in_4_6 *)&flow->local_addr);
                }
        } else if (cache_buffer.necp_cache_buf_type == NECP_CLIENT_CACHE_TYPE_TFO &&
-            cache_buffer.necp_cache_buf_ver == NECP_CLIENT_CACHE_TYPE_TFO_VER_1) {
+           cache_buffer.necp_cache_buf_ver == NECP_CLIENT_CACHE_TYPE_TFO_VER_1) {
                if (cache_buffer.necp_cache_buf_size != sizeof(necp_tcp_tfo_cache) ||
                    cache_buffer.necp_cache_buf_addr == USER_ADDR_NULL) {
                        error = EINVAL;
@@ -4448,14 +6005,14 @@ necp_client_update_cache(struct necp_fd_data *fd_data, struct necp_client_action
 
                if (client->current_route != NULL && client->current_route->rt_ifp != NULL) {
                        if (!client->platform_binary) {
-                           tfo_cache_buffer.necp_tcp_tfo_heuristics_success = 0;
+                               tfo_cache_buffer.necp_tcp_tfo_heuristics_success = 0;
                        }
                        tcp_heuristics_tfo_update(&tfo_cache_buffer, client->current_route->rt_ifp,
-                                                 (union sockaddr_in_4_6 *)&flow->local_addr,
-                                                 (union sockaddr_in_4_6 *)&flow->remote_addr);
+                           (union sockaddr_in_4_6 *)&flow->local_addr,
+                           (union sockaddr_in_4_6 *)&flow->remote_addr);
                }
        } else {
-           error = EINVAL;
+               error = EINVAL;
        }
 done_unlock:
        NECP_CLIENT_ROUTE_UNLOCK(client);
@@ -4463,7 +6020,120 @@ done_unlock:
        NECP_FD_UNLOCK(fd_data);
 done:
        *retval = error;
-       return (error);
+       return error;
+}
+
+#define NECP_CLIENT_ACTION_SIGN_DEFAULT_HOSTNAME_LENGTH 64
+#define NECP_CLIENT_ACTION_SIGN_MAX_HOSTNAME_LENGTH 1024
+
+#define NECP_CLIENT_ACTION_SIGN_TAG_LENGTH 32
+
+static NECP_CLIENT_ACTION_FUNCTION int
+necp_client_sign(__unused struct necp_fd_data *fd_data, struct necp_client_action_args *uap, int *retval)
+{
+       int error = 0;
+       u_int32_t hostname_length = 0;
+       u_int8_t tag[NECP_CLIENT_ACTION_SIGN_TAG_LENGTH] = {};
+       struct necp_client_signable signable = {};
+       union necp_sockaddr_union address_answer = {};
+       u_int8_t *client_hostname = NULL;
+       u_int8_t *allocated_hostname = NULL;
+       u_int8_t default_hostname[NECP_CLIENT_ACTION_SIGN_DEFAULT_HOSTNAME_LENGTH] = "";
+       uint32_t tag_size = sizeof(tag);
+
+       *retval = 0;
+
+       const bool has_resolver_entitlement = (priv_check_cred(kauth_cred_get(), PRIV_NET_VALIDATED_RESOLVER, 0) == 0);
+       if (!has_resolver_entitlement) {
+               NECPLOG0(LOG_ERR, "Process does not hold the necessary entitlement to sign resolver answers");
+               error = EPERM;
+               goto done;
+       }
+
+       if (uap->client_id == 0 || uap->client_id_len < sizeof(struct necp_client_signable)) {
+               error = EINVAL;
+               goto done;
+       }
+
+       if (uap->buffer == 0 || uap->buffer_size != NECP_CLIENT_ACTION_SIGN_TAG_LENGTH) {
+               error = EINVAL;
+               goto done;
+       }
+
+       error = copyin(uap->client_id, &signable, sizeof(signable));
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_sign copyin signable error (%d)", error);
+               goto done;
+       }
+
+       if (signable.sign_type != NECP_CLIENT_SIGN_TYPE_RESOLVER_ANSWER) {
+               NECPLOG(LOG_ERR, "necp_client_sign unknown signable type (%u)", signable.sign_type);
+               error = EINVAL;
+               goto done;
+       }
+
+       if (uap->client_id_len < sizeof(struct necp_client_resolver_answer)) {
+               error = EINVAL;
+               goto done;
+       }
+
+       error = copyin(uap->client_id + sizeof(signable), &address_answer, sizeof(address_answer));
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_sign copyin address_answer error (%d)", error);
+               goto done;
+       }
+
+       error = copyin(uap->client_id + sizeof(signable) + sizeof(address_answer), &hostname_length, sizeof(hostname_length));
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_sign copyin hostname_length error (%d)", error);
+               goto done;
+       }
+
+       if (hostname_length > NECP_CLIENT_ACTION_SIGN_MAX_HOSTNAME_LENGTH) {
+               error = EINVAL;
+               goto done;
+       }
+
+       if (hostname_length > NECP_CLIENT_ACTION_SIGN_DEFAULT_HOSTNAME_LENGTH) {
+               if ((allocated_hostname = _MALLOC(hostname_length, M_NECP, M_WAITOK | M_ZERO)) == NULL) {
+                       NECPLOG(LOG_ERR, "necp_client_sign malloc hostname %u failed", hostname_length);
+                       error = ENOMEM;
+                       goto done;
+               }
+
+               client_hostname = allocated_hostname;
+       } else {
+               client_hostname = default_hostname;
+       }
+
+       error = copyin(uap->client_id + sizeof(signable) + sizeof(address_answer) + sizeof(hostname_length), client_hostname, hostname_length);
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_sign copyin hostname error (%d)", error);
+               goto done;
+       }
+
+       address_answer.sin.sin_port = 0;
+       error = necp_sign_resolver_answer(signable.client_id, client_hostname, hostname_length,
+           (u_int8_t *)&address_answer, sizeof(address_answer),
+           tag, &tag_size);
+       if (tag_size != sizeof(tag)) {
+               NECPLOG(LOG_ERR, "necp_client_sign unexpected tag size %u", tag_size);
+               error = EINVAL;
+               goto done;
+       }
+       error = copyout(tag, uap->buffer, tag_size);
+       if (error) {
+               NECPLOG(LOG_ERR, "necp_client_sign copyout error (%d)", error);
+               goto done;
+       }
+
+done:
+       if (allocated_hostname != NULL) {
+               FREE(allocated_hostname, M_NECP);
+               allocated_hostname = NULL;
+       }
+       *retval = error;
+       return error;
 }
 
 int
@@ -4476,67 +6146,75 @@ necp_client_action(struct proc *p, struct necp_client_action_args *uap, int *ret
        error = necp_find_fd_data(uap->necp_fd, &fd_data);
        if (error != 0) {
                NECPLOG(LOG_ERR, "necp_client_action find fd error (%d)", error);
-               return (error);
+               return error;
        }
 
        u_int32_t action = uap->action;
        switch (action) {
-               case NECP_CLIENT_ACTION_ADD: {
-                       return_value = necp_client_add(p, fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_REMOVE: {
-                       return_value = necp_client_remove(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_PARAMETERS:
-               case NECP_CLIENT_ACTION_COPY_RESULT:
-               case NECP_CLIENT_ACTION_COPY_UPDATED_RESULT: {
-                       return_value = necp_client_copy(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_LIST: {
-                       return_value = necp_client_list(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_AGENT: {
-                       return_value = necp_client_agent_action(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_AGENT: {
-                       return_value = necp_client_copy_agent(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_AGENT_USE: {
-                       return_value = necp_client_agent_use(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_INTERFACE: {
-                       return_value = necp_client_copy_interface(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_ROUTE_STATISTICS: {
-                       return_value = necp_client_copy_route_statistics(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_UPDATE_CACHE: {
-                       return_value = necp_client_update_cache(fd_data, uap, retval);
-                       break;
-               }
-               case NECP_CLIENT_ACTION_COPY_CLIENT_UPDATE: {
-                       return_value = necp_client_copy_client_update(fd_data, uap, retval);
-                       break;
-               }
-               default: {
-                       NECPLOG(LOG_ERR, "necp_client_action unknown action (%u)", action);
-                       return_value = EINVAL;
-                       break;
-               }
+       case NECP_CLIENT_ACTION_ADD: {
+               return_value = necp_client_add(p, fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_CLAIM: {
+               return_value = necp_client_claim(p, fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_REMOVE: {
+               return_value = necp_client_remove(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_PARAMETERS:
+       case NECP_CLIENT_ACTION_COPY_RESULT:
+       case NECP_CLIENT_ACTION_COPY_UPDATED_RESULT: {
+               return_value = necp_client_copy(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_LIST: {
+               return_value = necp_client_list(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_AGENT: {
+               return_value = necp_client_agent_action(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_AGENT: {
+               return_value = necp_client_copy_agent(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_AGENT_USE: {
+               return_value = necp_client_agent_use(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_INTERFACE: {
+               return_value = necp_client_copy_interface(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_ROUTE_STATISTICS: {
+               return_value = necp_client_copy_route_statistics(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_UPDATE_CACHE: {
+               return_value = necp_client_update_cache(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_COPY_CLIENT_UPDATE: {
+               return_value = necp_client_copy_client_update(fd_data, uap, retval);
+               break;
+       }
+       case NECP_CLIENT_ACTION_SIGN: {
+               return_value = necp_client_sign(fd_data, uap, retval);
+               break;
+       }
+       default: {
+               NECPLOG(LOG_ERR, "necp_client_action unknown action (%u)", action);
+               return_value = EINVAL;
+               break;
+       }
        }
 
        file_drop(uap->necp_fd);
 
-       return (return_value);
+       return return_value;
 }
 
 #define NECP_MAX_MATCH_POLICY_PARAMETER_SIZE 1024
@@ -4546,7 +6224,7 @@ necp_match_policy(struct proc *p, struct necp_match_policy_args *uap, int32_t *r
 {
 #pragma unused(retval)
        u_int8_t *parameters = NULL;
-       struct necp_aggregate_result returned_result = {};
+       struct necp_aggregate_result returned_result;
        int error = 0;
 
        if (uap == NULL) {
@@ -4571,7 +6249,7 @@ necp_match_policy(struct proc *p, struct necp_match_policy_args *uap, int32_t *r
        }
 
        error = necp_application_find_policy_match_internal(p, parameters, uap->parameters_size,
-                                                                                                               &returned_result, NULL, 0, NULL, NULL, NULL, false);
+           &returned_result, NULL, NULL, 0, NULL, NULL, NULL, NULL, NULL, false, false, NULL);
        if (error) {
                goto done;
        }
@@ -4585,7 +6263,7 @@ done:
        if (parameters != NULL) {
                FREE(parameters, M_NECP);
        }
-       return (error);
+       return error;
 }
 
 /// Socket operations
@@ -4600,7 +6278,7 @@ necp_set_socket_attribute(u_int8_t *buffer, size_t buffer_length, u_int8_t type,
        char *local_string = NULL;
        u_int8_t *value = NULL;
 
-       cursor = necp_buffer_find_tlv(buffer, buffer_length, 0, type, 0);
+       cursor = necp_buffer_find_tlv(buffer, buffer_length, 0, type, NULL, 0);
        if (cursor < 0) {
                // This will clear out the parameter
                goto done;
@@ -4634,12 +6312,12 @@ done:
        }
 
        *buffer_p = local_string;
-       return (0);
+       return 0;
 fail:
        if (local_string != NULL) {
                FREE(local_string, M_NECP);
        }
-       return (error);
+       return error;
 }
 
 errno_t
@@ -4651,9 +6329,9 @@ necp_set_socket_attributes(struct socket *so, struct sockopt *sopt)
 
        if ((SOCK_DOM(so) != PF_INET
 #if INET6
-                && SOCK_DOM(so) != PF_INET6
+           && SOCK_DOM(so) != PF_INET6
 #endif
-                )) {
+           )) {
                error = EINVAL;
                goto done;
        }
@@ -4662,7 +6340,7 @@ necp_set_socket_attributes(struct socket *so, struct sockopt *sopt)
 
        size_t valsize = sopt->sopt_valsize;
        if (valsize == 0 ||
-               valsize > ((sizeof(struct necp_tlv_header) + NECP_MAX_SOCKET_ATTRIBUTE_STRING_LENGTH) * 2)) {
+           valsize > ((sizeof(struct necp_tlv_header) + NECP_MAX_SOCKET_ATTRIBUTE_STRING_LENGTH) * 2)) {
                goto done;
        }
 
@@ -4696,7 +6374,7 @@ done:
                FREE(buffer, M_NECP);
        }
 
-       return (error);
+       return error;
 }
 
 errno_t
@@ -4710,9 +6388,9 @@ necp_get_socket_attributes(struct socket *so, struct sockopt *sopt)
 
        if ((SOCK_DOM(so) != PF_INET
 #if INET6
-                && SOCK_DOM(so) != PF_INET6
+           && SOCK_DOM(so) != PF_INET6
 #endif
-                )) {
+           )) {
                error = EINVAL;
                goto done;
        }
@@ -4736,12 +6414,12 @@ necp_get_socket_attributes(struct socket *so, struct sockopt *sopt)
        cursor = buffer;
        if (inp->inp_necp_attributes.inp_domain != NULL) {
                cursor = necp_buffer_write_tlv(cursor, NECP_TLV_ATTRIBUTE_DOMAIN, strlen(inp->inp_necp_attributes.inp_domain), inp->inp_necp_attributes.inp_domain,
-                                                                          buffer, valsize);
+                   buffer, valsize);
        }
 
        if (inp->inp_necp_attributes.inp_account != NULL) {
                cursor = necp_buffer_write_tlv(cursor, NECP_TLV_ATTRIBUTE_ACCOUNT, strlen(inp->inp_necp_attributes.inp_account), inp->inp_necp_attributes.inp_account,
-                                                                          buffer, valsize);
+                   buffer, valsize);
        }
 
        error = sooptcopyout(sopt, buffer, valsize);
@@ -4753,20 +6431,19 @@ done:
                FREE(buffer, M_NECP);
        }
 
-       return (error);
+       return error;
 }
 
 void *
 necp_create_nexus_assign_message(uuid_t nexus_instance, u_int32_t nexus_port, void *key, uint32_t key_length,
-                                                                struct necp_client_endpoint *local_endpoint, struct necp_client_endpoint *remote_endpoint,
-                                                                u_int32_t flow_adv_index, size_t *message_length)
+    struct necp_client_endpoint *local_endpoint, struct necp_client_endpoint *remote_endpoint, struct ether_addr *local_ether_addr,
+    u_int32_t flow_adv_index, void *flow_stats, size_t *message_length)
 {
        u_int8_t *buffer = NULL;
        u_int8_t *cursor = NULL;
        size_t valsize = 0;
        bool has_nexus_assignment = FALSE;
 
-
        if (!uuid_is_null(nexus_instance)) {
                has_nexus_assignment = TRUE;
                valsize += sizeof(struct necp_tlv_header) + sizeof(uuid_t);
@@ -4784,13 +6461,19 @@ necp_create_nexus_assign_message(uuid_t nexus_instance, u_int32_t nexus_port, vo
        if (remote_endpoint != NULL) {
                valsize += sizeof(struct necp_tlv_header) + sizeof(struct necp_client_endpoint);
        }
+       if (local_ether_addr != NULL) {
+               valsize += sizeof(struct necp_tlv_header) + sizeof(struct ether_addr);
+       }
+       if (flow_stats != NULL) {
+               valsize += sizeof(struct necp_tlv_header) + sizeof(void *);
+       }
        if (valsize == 0) {
-               return (NULL);
+               return NULL;
        }
 
        MALLOC(buffer, u_int8_t *, valsize, M_NETAGENT, M_WAITOK | M_ZERO); // Use M_NETAGENT area, since it is expected upon free
        if (buffer == NULL) {
-               return (NULL);
+               return NULL;
        }
 
        cursor = buffer;
@@ -4810,10 +6493,16 @@ necp_create_nexus_assign_message(uuid_t nexus_instance, u_int32_t nexus_port, vo
        if (remote_endpoint != NULL) {
                cursor = necp_buffer_write_tlv(cursor, NECP_CLIENT_RESULT_REMOTE_ENDPOINT, sizeof(struct necp_client_endpoint), remote_endpoint, buffer, valsize);
        }
+       if (local_ether_addr != NULL) {
+               cursor = necp_buffer_write_tlv(cursor, NECP_CLIENT_RESULT_LOCAL_ETHER_ADDR, sizeof(struct ether_addr), local_ether_addr, buffer, valsize);
+       }
+       if (flow_stats != NULL) {
+               cursor = necp_buffer_write_tlv(cursor, NECP_CLIENT_RESULT_NEXUS_FLOW_STATS, sizeof(void *), &flow_stats, buffer, valsize);
+       }
 
        *message_length = valsize;
 
-       return (buffer);
+       return buffer;
 }
 
 void
@@ -4828,6 +6517,7 @@ necp_inpcb_remove_cb(struct inpcb *inp)
 void
 necp_inpcb_dispose(struct inpcb *inp)
 {
+       necp_inpcb_remove_cb(inp); // Clear out socket registrations if not yet done
        if (inp->inp_necp_attributes.inp_domain != NULL) {
                FREE(inp->inp_necp_attributes.inp_domain, M_NECP);
                inp->inp_necp_attributes.inp_domain = NULL;
@@ -4852,78 +6542,71 @@ necp_mppcb_dispose(struct mppcb *mpp)
 errno_t
 necp_client_init(void)
 {
-       errno_t result = 0;
-
        necp_fd_grp_attr = lck_grp_attr_alloc_init();
        if (necp_fd_grp_attr == NULL) {
-               NECPLOG0(LOG_ERR, "lck_grp_attr_alloc_init failed");
-               result = ENOMEM;
-               goto done;
+               panic("lck_grp_attr_alloc_init failed\n");
+               /* NOTREACHED */
        }
 
        necp_fd_mtx_grp = lck_grp_alloc_init("necp_fd", necp_fd_grp_attr);
        if (necp_fd_mtx_grp == NULL) {
-               NECPLOG0(LOG_ERR, "lck_grp_alloc_init failed");
-               result = ENOMEM;
-               goto done;
+               panic("lck_grp_alloc_init failed\n");
+               /* NOTREACHED */
        }
 
        necp_fd_mtx_attr = lck_attr_alloc_init();
        if (necp_fd_mtx_attr == NULL) {
-               NECPLOG0(LOG_ERR, "lck_attr_alloc_init failed");
-               result = ENOMEM;
-               goto done;
+               panic("lck_attr_alloc_init failed\n");
+               /* NOTREACHED */
        }
 
        necp_client_fd_size = sizeof(struct necp_fd_data);
        necp_client_fd_zone = zinit(necp_client_fd_size,
-                                                               NECP_CLIENT_FD_ZONE_MAX * necp_client_fd_size,
-                                                               0, NECP_CLIENT_FD_ZONE_NAME);
+           NECP_CLIENT_FD_ZONE_MAX * necp_client_fd_size,
+           0, NECP_CLIENT_FD_ZONE_NAME);
        if (necp_client_fd_zone == NULL) {
-               NECPLOG0(LOG_ERR, "zinit(necp_client_fd) failed");
-               result = ENOMEM;
-               goto done;
+               panic("zinit(necp_client_fd) failed\n");
+               /* NOTREACHED */
        }
 
        necp_flow_size = sizeof(struct necp_client_flow);
-       necp_flow_zone = zinit(necp_flow_size,
-                                                  NECP_FLOW_ZONE_MAX * necp_flow_size,
-                                                  0, NECP_FLOW_ZONE_NAME);
-       if (necp_flow_zone == NULL) {
-               NECPLOG0(LOG_ERR, "zinit(necp_flow) failed");
-               result = ENOMEM;
-               goto done;
+       necp_flow_cache = mcache_create(NECP_FLOW_ZONE_NAME, necp_flow_size, sizeof(uint64_t), 0, MCR_SLEEP);
+       if (necp_flow_cache == NULL) {
+               panic("mcache_create(necp_flow_cache) failed\n");
+               /* NOTREACHED */
+       }
+
+       necp_flow_registration_size = sizeof(struct necp_client_flow_registration);
+       necp_flow_registration_cache = mcache_create(NECP_FLOW_REGISTRATION_ZONE_NAME, necp_flow_registration_size, sizeof(uint64_t), 0, MCR_SLEEP);
+       if (necp_flow_registration_cache == NULL) {
+               panic("mcache_create(necp_client_flow_registration) failed\n");
+               /* NOTREACHED */
        }
 
        necp_client_update_tcall = thread_call_allocate_with_options(necp_update_all_clients_callout, NULL,
-                                                                                                                                THREAD_CALL_PRIORITY_KERNEL, THREAD_CALL_OPTIONS_ONCE);
+           THREAD_CALL_PRIORITY_KERNEL, THREAD_CALL_OPTIONS_ONCE);
        VERIFY(necp_client_update_tcall != NULL);
 
        lck_rw_init(&necp_fd_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
        lck_rw_init(&necp_observer_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
        lck_rw_init(&necp_client_tree_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
+       lck_rw_init(&necp_flow_tree_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
        lck_rw_init(&necp_collect_stats_list_lock, necp_fd_mtx_grp, necp_fd_mtx_attr);
 
        LIST_INIT(&necp_fd_list);
        LIST_INIT(&necp_fd_observer_list);
-       LIST_INIT(&necp_collect_stats_client_list);
+       LIST_INIT(&necp_collect_stats_flow_list);
 
        RB_INIT(&necp_client_global_tree);
+       RB_INIT(&necp_client_flow_global_tree);
 
-done:
-       if (result != 0) {
-               if (necp_fd_mtx_attr != NULL) {
-                       lck_attr_free(necp_fd_mtx_attr);
-                       necp_fd_mtx_attr = NULL;
-               }
-               if (necp_fd_mtx_grp != NULL) {
-                       lck_grp_free(necp_fd_mtx_grp);
-                       necp_fd_mtx_grp = NULL;
-               }
-               if (necp_fd_grp_attr != NULL) {
-                       lck_grp_attr_free(necp_fd_grp_attr);
-                       necp_fd_grp_attr = NULL;
-               }
-       }
-       return (result);
+       return 0;
+}
+
+void
+necp_client_reap_caches(boolean_t purge)
+{
+       mcache_reap_now(necp_flow_cache, purge);
+       mcache_reap_now(necp_flow_registration_cache, purge);
 }
+