xnu-7195.81.3.tar.gz

[apple/xnu.git] / bsd / netinet / tcp_timer.c

diff --git a/bsd/netinet/tcp_timer.c b/bsd/netinet/tcp_timer.c
index aa2317164e82fc8f0e50e31efcc4526f88dda69f..5012199aa4b70c2603795edecb656cb294d1fd97 100644 (file)
--- a/bsd/netinet/tcp_timer.c
+++ b/bsd/netinet/tcp_timer.c
@@ -1,8 +1,8 @@
 /*
 /*

- * Copyright (c) 2000-2014 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2020 Apple Inc. All rights reserved.

  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@

- * 
+ *

  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in


@@ -11,10 +11,10 @@
  * unlawful or unlicensed copies of an Apple operating system, or to
  * circumvent, violate, or enable the circumvention or violation of, any
  * terms of an Apple operating system software license agreement.
  * unlawful or unlicensed copies of an Apple operating system, or to
  * circumvent, violate, or enable the circumvention or violation of, any
  * terms of an Apple operating system software license agreement.

- * 
+ *

  * Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  * Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this file.

- * 
+ *

  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,


@@ -22,7 +22,7 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.

- * 
+ *

  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*


@@ -74,7 +74,7 @@
 #include <sys/mcache.h>
 #include <sys/queue.h>
 #include <kern/locks.h>
 #include <sys/mcache.h>
 #include <sys/queue.h>
 #include <kern/locks.h>

-#include <kern/cpu_number.h>   /* before tcp_seq.h, for tcp_random18() */
+#include <kern/cpu_number.h>    /* before tcp_seq.h, for tcp_random18() */

 #include <mach/boolean.h>
 
 #include <net/route.h>
 #include <mach/boolean.h>
 
 #include <net/route.h>


@@ -84,52 +84,35 @@
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/in_pcb.h>
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/in_pcb.h>

-#if INET6
+#include <netinet/in_var.h>

 #include <netinet6/in6_pcb.h>
 #include <netinet6/in6_pcb.h>

-#endif

 #include <netinet/ip_var.h>
 #include <netinet/tcp.h>
 #include <netinet/ip_var.h>
 #include <netinet/tcp.h>

+#include <netinet/tcp_cache.h>

 #include <netinet/tcp_fsm.h>
 #include <netinet/tcp_seq.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
 #include <netinet/tcp_cc.h>
 #include <netinet/tcp_fsm.h>
 #include <netinet/tcp_seq.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
 #include <netinet/tcp_cc.h>

-#if INET6

 #include <netinet6/tcp6_var.h>
 #include <netinet6/tcp6_var.h>

-#endif

 #include <netinet/tcpip.h>
 #if TCPDEBUG
 #include <netinet/tcp_debug.h>
 #endif
 #include <netinet/tcpip.h>
 #if TCPDEBUG
 #include <netinet/tcp_debug.h>
 #endif

+#include <netinet/tcp_log.h>
+

 #include <sys/kdebug.h>
 #include <mach/sdt.h>
 #include <netinet/mptcp_var.h>
 
 #include <sys/kdebug.h>
 #include <mach/sdt.h>
 #include <netinet/mptcp_var.h>
 

-#define TIMERENTRY_TO_TP(te) ((struct tcpcb *)((uintptr_t)te - offsetof(struct tcpcb, tentry.le.le_next))) 
-
-#define VERIFY_NEXT_LINK(elm,field) do {       \
-       if (LIST_NEXT((elm),field) != NULL &&   \
-           LIST_NEXT((elm),field)->field.le_prev !=    \
-               &((elm)->field.le_next))        \
-               panic("Bad link elm %p next->prev != elm", (elm));      \
-} while(0)
-
-#define VERIFY_PREV_LINK(elm,field) do {       \
-       if (*(elm)->field.le_prev != (elm))     \
-               panic("Bad link elm %p prev->next != elm", (elm));      \
-} while(0)
-
-#define TCP_SET_TIMER_MODE(mode, i) do { \
-       if (IS_TIMER_HZ_10MS(i)) \
-               (mode) |= TCP_TIMERLIST_10MS_MODE; \
-       else if (IS_TIMER_HZ_100MS(i)) \
-               (mode) |= TCP_TIMERLIST_100MS_MODE; \
-       else \
-               (mode) |= TCP_TIMERLIST_500MS_MODE; \
-} while(0)
-

 /* Max number of times a stretch ack can be delayed on a connection */
 /* Max number of times a stretch ack can be delayed on a connection */

-#define        TCP_STRETCHACK_DELAY_THRESHOLD  5
+#define TCP_STRETCHACK_DELAY_THRESHOLD  5
+
+/*
+ * If the host processor has been sleeping for too long, this is the threshold
+ * used to avoid sending stale retransmissions.
+ */
+#define TCP_SLEEP_TOO_LONG      (10 * 60 * 1000) /* 10 minutes in ms */

 
 /* tcp timer list */
 struct tcptimerlist tcp_timer_list;
 
 /* tcp timer list */
 struct tcptimerlist tcp_timer_list;


@@ -140,50 +123,88 @@ struct tcptailq tcp_tw_tailq;
 static int
 sysctl_msec_to_ticks SYSCTL_HANDLER_ARGS
 {
 static int
 sysctl_msec_to_ticks SYSCTL_HANDLER_ARGS
 {

-#pragma unused(arg1, arg2)
-       int error, s, tt;
-
-       tt = *(int *)oidp->oid_arg1;
-       s = tt * 1000 / TCP_RETRANSHZ;;
+#pragma unused(arg2)
+       int error, temp;
+       long s, tt;
+
+       tt = *(int *)arg1;
+       s = tt * 1000 / TCP_RETRANSHZ;
+       if (tt < 0 || s > INT_MAX) {
+               return EINVAL;
+       }
+       temp = (int)s;

 
 

-       error = sysctl_handle_int(oidp, &s, 0, req);
-       if (error || !req->newptr)
-               return (error);
+       error = sysctl_handle_int(oidp, &temp, 0, req);
+       if (error || !req->newptr) {
+               return error;
+       }

 
 

-       tt = s * TCP_RETRANSHZ / 1000;
-       if (tt < 1)
-               return (EINVAL);
+       tt = temp * TCP_RETRANSHZ / 1000;
+       if (tt < 1 || tt > INT_MAX) {
+               return EINVAL;
+       }

 
 

-       *(int *)oidp->oid_arg1 = tt;
-        return (0);
+       *(int *)arg1 = (int)tt;
+       SYSCTL_SKMEM_UPDATE_AT_OFFSET(arg2, *(int*)arg1);
+       return 0;

 }
 
 }
 

-int    tcp_keepinit;
+#if SYSCTL_SKMEM
+int     tcp_keepinit = TCPTV_KEEP_INIT;
+SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_keepinit, offsetof(skmem_sysctl, tcp.keepinit),
+    sysctl_msec_to_ticks, "I", "");
+
+int     tcp_keepidle = TCPTV_KEEP_IDLE;
+SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_keepidle, offsetof(skmem_sysctl, tcp.keepidle),
+    sysctl_msec_to_ticks, "I", "");
+
+int     tcp_keepintvl = TCPTV_KEEPINTVL;
+SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_keepintvl, offsetof(skmem_sysctl, tcp.keepintvl),
+    sysctl_msec_to_ticks, "I", "");
+
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, keepcnt,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    int, tcp_keepcnt, TCPTV_KEEPCNT, "number of times to repeat keepalive");
+
+int     tcp_msl = TCPTV_MSL;
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_msl, offsetof(skmem_sysctl, tcp.msl),
+    sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
+#else /* SYSCTL_SKMEM */
+int     tcp_keepinit;

 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
 
 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
 

-int    tcp_keepidle;
+int     tcp_keepidle;

 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
 
 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
 

-int    tcp_keepintvl;
+int     tcp_keepintvl;

 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
 
 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
 

-int    tcp_keepcnt;
+int     tcp_keepcnt;

 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepcnt, 0, "number of times to repeat keepalive");
 
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_keepcnt, 0, "number of times to repeat keepalive");
 

-int    tcp_msl;
+int     tcp_msl;

 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");

+#endif /* SYSCTL_SKMEM */

 
 

-/* 
+/*

  * Avoid DoS via TCP Robustness in Persist Condition
  * (see http://www.ietf.org/id/draft-ananth-tcpm-persist-02.txt)
  * by allowing a system wide maximum persistence timeout value when in
  * Avoid DoS via TCP Robustness in Persist Condition
  * (see http://www.ietf.org/id/draft-ananth-tcpm-persist-02.txt)
  * by allowing a system wide maximum persistence timeout value when in


@@ -192,26 +213,32 @@ SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
  * Expressed in milliseconds to be consistent without timeout related
  * values, the TCP socket option is in seconds.
  */
  * Expressed in milliseconds to be consistent without timeout related
  * values, the TCP socket option is in seconds.
  */

+#if SYSCTL_SKMEM
+u_int32_t tcp_max_persist_timeout = 0;
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, max_persist_timeout,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_max_persist_timeout, offsetof(skmem_sysctl, tcp.max_persist_timeout),
+    sysctl_msec_to_ticks, "I", "Maximum persistence timeout for ZWP");
+#else /* SYSCTL_SKMEM */

 u_int32_t tcp_max_persist_timeout = 0;
 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, max_persist_timeout,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
 u_int32_t tcp_max_persist_timeout = 0;
 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, max_persist_timeout,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,

-    &tcp_max_persist_timeout, 0, sysctl_msec_to_ticks, "I", 
+    &tcp_max_persist_timeout, 0, sysctl_msec_to_ticks, "I",

     "Maximum persistence timeout for ZWP");
     "Maximum persistence timeout for ZWP");

+#endif /* SYSCTL_SKMEM */

 
 

-static int     always_keepalive = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive,
-    CTLFLAG_RW | CTLFLAG_LOCKED,
-    &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, always_keepalive,
+    CTLFLAG_RW | CTLFLAG_LOCKED, static int, always_keepalive, 0,
+    "Assume SO_KEEPALIVE on all TCP connections");

 
 /*
  * This parameter determines how long the timer list will stay in fast or
 
 /*
  * This parameter determines how long the timer list will stay in fast or

- * quick mode even though all connections are idle. In this state, the 
+ * quick mode even though all connections are idle. In this state, the

  * timer will run more frequently anticipating new data.
  */
  * timer will run more frequently anticipating new data.
  */

-int timer_fastmode_idlemax = TCP_FASTMODE_IDLERUN_MAX;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_fastmode_idlemax,
-    CTLFLAG_RW | CTLFLAG_LOCKED,
-    &timer_fastmode_idlemax, 0, "Maximum idle generations in fast mode");
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, timer_fastmode_idlemax,
+    CTLFLAG_RW | CTLFLAG_LOCKED, int, timer_fastmode_idlemax,
+    TCP_FASTMODE_IDLERUN_MAX, "Maximum idle generations in fast mode");

 
 /*
  * See tcp_syn_backoff[] for interval values between SYN retransmits;
 
 /*
  * See tcp_syn_backoff[] for interval values between SYN retransmits;


@@ -220,18 +247,9 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_fastmode_idlemax,
  * SYN retransmits.  Setting it to 0 disables the dropping off of those
  * two options.
  */
  * SYN retransmits.  Setting it to 0 disables the dropping off of those
  * two options.
  */

-static int tcp_broken_peer_syn_rxmit_thres = 7;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, broken_peer_syn_rxmit_thres,
-    CTLFLAG_RW | CTLFLAG_LOCKED,
-    &tcp_broken_peer_syn_rxmit_thres, 0, 
-    "Number of retransmitted SYNs before "
-    "TCP disables rfc1323 and rfc1644 during the rest of attempts");
-
-/* A higher threshold on local connections for disabling RFC 1323 options */
-static int tcp_broken_peer_syn_rxmit_thres_local = 10;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, broken_peer_syn_rexmit_thres_local, 
-    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_broken_peer_syn_rxmit_thres_local, 0,
-    "Number of retransmitted SYNs before disabling RFC 1323 "
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, broken_peer_syn_rexmit_thres,
+    CTLFLAG_RW | CTLFLAG_LOCKED, static int, tcp_broken_peer_syn_rxmit_thres,
+    10, "Number of retransmitted SYNs before disabling RFC 1323 "

     "options on local connections");
 
 static int tcp_timer_advanced = 0;
     "options on local connections");
 
 static int tcp_timer_advanced = 0;


@@ -241,61 +259,137 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_timer_advanced,
 
 static int tcp_resched_timerlist = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_resched_timerlist,
 
 static int tcp_resched_timerlist = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_resched_timerlist,

-    CTLFLAG_RD | CTLFLAG_LOCKED, &tcp_resched_timerlist, 0, 
+    CTLFLAG_RD | CTLFLAG_LOCKED, &tcp_resched_timerlist, 0,

     "Number of times timer list was rescheduled as part of processing a packet");
 
     "Number of times timer list was rescheduled as part of processing a packet");
 

-int    tcp_pmtud_black_hole_detect = 1 ;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
-    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_pmtud_black_hole_detect, 0,
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, pmtud_blackhole_detection,
+    CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_pmtud_black_hole_detect, 1,

     "Path MTU Discovery Black Hole Detection");
 
     "Path MTU Discovery Black Hole Detection");
 

-int    tcp_pmtud_black_hole_mss = 1200 ;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
-    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_pmtud_black_hole_mss, 0,
+SYSCTL_SKMEM_TCP_INT(OID_AUTO, pmtud_blackhole_mss,
+    CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_pmtud_black_hole_mss, 1200,

     "Path MTU Discovery Black Hole Detection lowered MSS");
 
     "Path MTU Discovery Black Hole Detection lowered MSS");
 

+#if (DEBUG || DEVELOPMENT)
+int tcp_probe_if_fix_port = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, probe_if_fix_port,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_probe_if_fix_port, 0, "");
+#endif /* (DEBUG || DEVELOPMENT) */
+
+static u_int32_t tcp_mss_rec_medium = 1200;
+static u_int32_t tcp_mss_rec_low = 512;
+
+#define TCP_REPORT_STATS_INTERVAL       43200 /* 12 hours, in seconds */
+int tcp_report_stats_interval = TCP_REPORT_STATS_INTERVAL;
+

 /* performed garbage collection of "used" sockets */
 static boolean_t tcp_gc_done = FALSE;
 
 /* max idle probes */
 /* performed garbage collection of "used" sockets */
 static boolean_t tcp_gc_done = FALSE;
 
 /* max idle probes */

-int    tcp_maxpersistidle;
+int     tcp_maxpersistidle = TCPTV_KEEP_IDLE;

 
 /*
  * TCP delack timer is set to 100 ms. Since the processing of timer list
  * in fast mode will happen no faster than 100 ms, the delayed ack timer
  * will fire some where between 100 and 200 ms.
  */
 
 /*
  * TCP delack timer is set to 100 ms. Since the processing of timer list
  * in fast mode will happen no faster than 100 ms, the delayed ack timer
  * will fire some where between 100 and 200 ms.
  */

-int    tcp_delack = TCP_RETRANSHZ / 10;
+int     tcp_delack = TCP_RETRANSHZ / 10;

 
 #if MPTCP
 /*
  * MP_JOIN retransmission of 3rd ACK will be every 500 msecs without backoff
  */
 
 #if MPTCP
 /*
  * MP_JOIN retransmission of 3rd ACK will be every 500 msecs without backoff
  */

-int    tcp_jack_rxmt = TCP_RETRANSHZ / 2;
+int     tcp_jack_rxmt = TCP_RETRANSHZ / 2;

 #endif /* MPTCP */
 
 #endif /* MPTCP */
 

+static boolean_t tcp_itimer_done = FALSE;
+

 static void tcp_remove_timer(struct tcpcb *tp);
 static void tcp_sched_timerlist(uint32_t offset);
 static void tcp_remove_timer(struct tcpcb *tp);
 static void tcp_sched_timerlist(uint32_t offset);

-static u_int32_t tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *mode);
-static void tcp_sched_timers(struct tcpcb *tp);
+static u_int32_t tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *mode,
+    u_int16_t probe_if_index);

 static inline void tcp_set_lotimer_index(struct tcpcb *);
 static inline void tcp_set_lotimer_index(struct tcpcb *);

-static void tcp_rexmt_save_state(struct tcpcb *tp);

 __private_extern__ void tcp_remove_from_time_wait(struct inpcb *inp);
 __private_extern__ void tcp_remove_from_time_wait(struct inpcb *inp);

+static inline void tcp_update_mss_core(struct tcpcb *tp, struct ifnet *ifp);

 __private_extern__ void tcp_report_stats(void);
 
 __private_extern__ void tcp_report_stats(void);
 

+static  u_int64_t tcp_last_report_time;
+

 /*
 /*

- * Macro to compare two timers. If there is a reset of the sign bit, 
- * it is safe to assume that the timer has wrapped around. By doing 
- * signed comparision, we take care of wrap around such that the value 
- * with the sign bit reset is actually ahead of the other.
+ * Structure to store previously reported stats so that we can send
+ * incremental changes in each report interval.

  */
  */

-inline int32_t
-timer_diff(uint32_t t1, uint32_t toff1, uint32_t t2, uint32_t toff2) { 
-       return (int32_t)((t1 + toff1) - (t2 + toff2));
+struct tcp_last_report_stats {
+       u_int32_t       tcps_connattempt;
+       u_int32_t       tcps_accepts;
+       u_int32_t       tcps_ecn_client_setup;
+       u_int32_t       tcps_ecn_server_setup;
+       u_int32_t       tcps_ecn_client_success;
+       u_int32_t       tcps_ecn_server_success;
+       u_int32_t       tcps_ecn_not_supported;
+       u_int32_t       tcps_ecn_lost_syn;
+       u_int32_t       tcps_ecn_lost_synack;
+       u_int32_t       tcps_ecn_recv_ce;
+       u_int32_t       tcps_ecn_recv_ece;
+       u_int32_t       tcps_ecn_sent_ece;
+       u_int32_t       tcps_ecn_conn_recv_ce;
+       u_int32_t       tcps_ecn_conn_recv_ece;
+       u_int32_t       tcps_ecn_conn_plnoce;
+       u_int32_t       tcps_ecn_conn_pl_ce;
+       u_int32_t       tcps_ecn_conn_nopl_ce;
+       u_int32_t       tcps_ecn_fallback_synloss;
+       u_int32_t       tcps_ecn_fallback_reorder;
+       u_int32_t       tcps_ecn_fallback_ce;
+
+       /* TFO-related statistics */
+       u_int32_t       tcps_tfo_syn_data_rcv;
+       u_int32_t       tcps_tfo_cookie_req_rcv;
+       u_int32_t       tcps_tfo_cookie_sent;
+       u_int32_t       tcps_tfo_cookie_invalid;
+       u_int32_t       tcps_tfo_cookie_req;
+       u_int32_t       tcps_tfo_cookie_rcv;
+       u_int32_t       tcps_tfo_syn_data_sent;
+       u_int32_t       tcps_tfo_syn_data_acked;
+       u_int32_t       tcps_tfo_syn_loss;
+       u_int32_t       tcps_tfo_blackhole;
+       u_int32_t       tcps_tfo_cookie_wrong;
+       u_int32_t       tcps_tfo_no_cookie_rcv;
+       u_int32_t       tcps_tfo_heuristics_disable;
+       u_int32_t       tcps_tfo_sndblackhole;
+
+       /* MPTCP-related statistics */
+       u_int32_t       tcps_mptcp_handover_attempt;
+       u_int32_t       tcps_mptcp_interactive_attempt;
+       u_int32_t       tcps_mptcp_aggregate_attempt;
+       u_int32_t       tcps_mptcp_fp_handover_attempt;
+       u_int32_t       tcps_mptcp_fp_interactive_attempt;
+       u_int32_t       tcps_mptcp_fp_aggregate_attempt;
+       u_int32_t       tcps_mptcp_heuristic_fallback;
+       u_int32_t       tcps_mptcp_fp_heuristic_fallback;
+       u_int32_t       tcps_mptcp_handover_success_wifi;
+       u_int32_t       tcps_mptcp_handover_success_cell;
+       u_int32_t       tcps_mptcp_interactive_success;
+       u_int32_t       tcps_mptcp_aggregate_success;
+       u_int32_t       tcps_mptcp_fp_handover_success_wifi;
+       u_int32_t       tcps_mptcp_fp_handover_success_cell;
+       u_int32_t       tcps_mptcp_fp_interactive_success;
+       u_int32_t       tcps_mptcp_fp_aggregate_success;
+       u_int32_t       tcps_mptcp_handover_cell_from_wifi;
+       u_int32_t       tcps_mptcp_handover_wifi_from_cell;
+       u_int32_t       tcps_mptcp_interactive_cell_from_wifi;
+       u_int64_t       tcps_mptcp_handover_cell_bytes;
+       u_int64_t       tcps_mptcp_interactive_cell_bytes;
+       u_int64_t       tcps_mptcp_aggregate_cell_bytes;
+       u_int64_t       tcps_mptcp_handover_all_bytes;
+       u_int64_t       tcps_mptcp_interactive_all_bytes;
+       u_int64_t       tcps_mptcp_aggregate_all_bytes;
+       u_int32_t       tcps_mptcp_back_to_wifi;
+       u_int32_t       tcps_mptcp_wifi_proxy;
+       u_int32_t       tcps_mptcp_cell_proxy;
+       u_int32_t       tcps_mptcp_triggered_cell;

 };
 
 };
 

-static u_int64_t tcp_last_report_time;
-#define        TCP_REPORT_STATS_INTERVAL       345600 /* 4 days, in seconds */

 
 /* Returns true if the timer is on the timer list */
 #define TIMER_IS_ON_LIST(tp) ((tp)->t_flags & TF_TIMER_ONLIST)
 
 /* Returns true if the timer is on the timer list */
 #define TIMER_IS_ON_LIST(tp) ((tp)->t_flags & TF_TIMER_ONLIST)


@@ -307,6 +401,97 @@ static     u_int64_t tcp_last_report_time;
 static void add_to_time_wait_locked(struct tcpcb *tp, uint32_t delay);
 static boolean_t tcp_garbage_collect(struct inpcb *, int);
 
 static void add_to_time_wait_locked(struct tcpcb *tp, uint32_t delay);
 static boolean_t tcp_garbage_collect(struct inpcb *, int);
 

+#define TIMERENTRY_TO_TP(te) ((struct tcpcb *)((uintptr_t)te - offsetof(struct tcpcb, tentry.le.le_next)))
+
+#define VERIFY_NEXT_LINK(elm, field) do {       \
+       if (LIST_NEXT((elm),field) != NULL &&   \
+           LIST_NEXT((elm),field)->field.le_prev !=    \
+               &((elm)->field.le_next))        \
+               panic("Bad link elm %p next->prev != elm", (elm));      \
+} while(0)
+
+#define VERIFY_PREV_LINK(elm, field) do {       \
+       if (*(elm)->field.le_prev != (elm))     \
+               panic("Bad link elm %p prev->next != elm", (elm));      \
+} while(0)
+
+#define TCP_SET_TIMER_MODE(mode, i) do { \
+       if (IS_TIMER_HZ_10MS(i)) \
+               (mode) |= TCP_TIMERLIST_10MS_MODE; \
+       else if (IS_TIMER_HZ_100MS(i)) \
+               (mode) |= TCP_TIMERLIST_100MS_MODE; \
+       else \
+               (mode) |= TCP_TIMERLIST_500MS_MODE; \
+} while(0)
+
+#if (DEVELOPMENT || DEBUG)
+SYSCTL_UINT(_net_inet_tcp, OID_AUTO, mss_rec_medium,
+    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_mss_rec_medium, 0,
+    "Medium MSS based on recommendation in link status report");
+SYSCTL_UINT(_net_inet_tcp, OID_AUTO, mss_rec_low,
+    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_mss_rec_low, 0,
+    "Low MSS based on recommendation in link status report");
+
+static int32_t tcp_change_mss_recommended = 0;
+static int
+sysctl_change_mss_recommended SYSCTL_HANDLER_ARGS
+{
+#pragma unused(oidp, arg1, arg2)
+       int i, err = 0, changed = 0;
+       struct ifnet *ifp;
+       struct if_link_status ifsr;
+       struct if_cellular_status_v1 *new_cell_sr;
+       err = sysctl_io_number(req, tcp_change_mss_recommended,
+           sizeof(int32_t), &i, &changed);
+       if (changed) {
+               if (i < 0 || i > UINT16_MAX) {
+                       return EINVAL;
+               }
+               ifnet_head_lock_shared();
+               TAILQ_FOREACH(ifp, &ifnet_head, if_link) {
+                       if (IFNET_IS_CELLULAR(ifp)) {
+                               bzero(&ifsr, sizeof(ifsr));
+                               new_cell_sr = &ifsr.ifsr_u.ifsr_cell.if_cell_u.if_status_v1;
+                               ifsr.ifsr_version = IF_CELLULAR_STATUS_REPORT_CURRENT_VERSION;
+                               ifsr.ifsr_len = sizeof(*new_cell_sr);
+
+                               /* Set MSS recommended */
+                               new_cell_sr->valid_bitmask |= IF_CELL_UL_MSS_RECOMMENDED_VALID;
+                               new_cell_sr->mss_recommended = (uint16_t)i;
+                               err = ifnet_link_status_report(ifp, new_cell_sr, sizeof(new_cell_sr));
+                               if (err == 0) {
+                                       tcp_change_mss_recommended = i;
+                               } else {
+                                       break;
+                               }
+                       }
+               }
+               ifnet_head_done();
+       }
+       return err;
+}
+
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, change_mss_recommended,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_change_mss_recommended,
+    0, sysctl_change_mss_recommended, "IU", "Change MSS recommended");
+
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, report_stats_interval,
+    CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_report_stats_interval, 0,
+    "Report stats interval");
+#endif /* (DEVELOPMENT || DEBUG) */
+
+/*
+ * Macro to compare two timers. If there is a reset of the sign bit,
+ * it is safe to assume that the timer has wrapped around. By doing
+ * signed comparision, we take care of wrap around such that the value
+ * with the sign bit reset is actually ahead of the other.
+ */
+inline int32_t
+timer_diff(uint32_t t1, uint32_t toff1, uint32_t t2, uint32_t toff2)
+{
+       return (int32_t)((t1 + toff1) - (t2 + toff2));
+}
+

 /*
  * Add to tcp timewait list, delay is given in milliseconds.
  */
 /*
  * Add to tcp timewait list, delay is given in milliseconds.
  */


@@ -318,13 +503,13 @@ add_to_time_wait_locked(struct tcpcb *tp, uint32_t delay)
        uint32_t timer;
 
        /* pcb list should be locked when we get here */
        uint32_t timer;
 
        /* pcb list should be locked when we get here */

-       lck_rw_assert(pcbinfo->ipi_lock, LCK_RW_ASSERT_EXCLUSIVE);
+       LCK_RW_ASSERT(pcbinfo->ipi_lock, LCK_RW_ASSERT_EXCLUSIVE);

 
        /* We may get here multiple times, so check */
        if (!(inp->inp_flags2 & INP2_TIMEWAIT)) {
                pcbinfo->ipi_twcount++;
                inp->inp_flags2 |= INP2_TIMEWAIT;
 
        /* We may get here multiple times, so check */
        if (!(inp->inp_flags2 & INP2_TIMEWAIT)) {
                pcbinfo->ipi_twcount++;
                inp->inp_flags2 |= INP2_TIMEWAIT;

-               
+

                /* Remove from global inp list */
                LIST_REMOVE(inp, inp_list);
        } else {
                /* Remove from global inp list */
                LIST_REMOVE(inp, inp_list);
        } else {


@@ -333,11 +518,12 @@ add_to_time_wait_locked(struct tcpcb *tp, uint32_t delay)
 
        /* Compute the time at which this socket can be closed */
        timer = tcp_now + delay;
 
        /* Compute the time at which this socket can be closed */
        timer = tcp_now + delay;

-       
+

        /* We will use the TCPT_2MSL timer for tracking this delay */
 
        /* We will use the TCPT_2MSL timer for tracking this delay */
 

-       if (TIMER_IS_ON_LIST(tp))
+       if (TIMER_IS_ON_LIST(tp)) {

                tcp_remove_timer(tp);
                tcp_remove_timer(tp);

+       }

        tp->t_timer[TCPT_2MSL] = timer;
 
        TAILQ_INSERT_TAIL(&tcp_tw_tailq, tp, t_twentry);
        tp->t_timer[TCPT_2MSL] = timer;
 
        TAILQ_INSERT_TAIL(&tcp_tw_tailq, tp, t_twentry);


@@ -347,13 +533,19 @@ void
 add_to_time_wait(struct tcpcb *tp, uint32_t delay)
 {
        struct inpcbinfo *pcbinfo = &tcbinfo;
 add_to_time_wait(struct tcpcb *tp, uint32_t delay)
 {
        struct inpcbinfo *pcbinfo = &tcbinfo;

-       if (tp->t_inpcb->inp_socket->so_options & SO_NOWAKEFROMSLEEP)
+       if (tp->t_inpcb->inp_socket->so_options & SO_NOWAKEFROMSLEEP) {

                socket_post_kev_msg_closed(tp->t_inpcb->inp_socket);
                socket_post_kev_msg_closed(tp->t_inpcb->inp_socket);

+       }
+
+       tcp_del_fsw_flow(tp);
+
+       /* 19182803: Notify nstat that connection is closing before waiting. */
+       nstat_pcb_detach(tp->t_inpcb);

 
        if (!lck_rw_try_lock_exclusive(pcbinfo->ipi_lock)) {
 
        if (!lck_rw_try_lock_exclusive(pcbinfo->ipi_lock)) {

-               tcp_unlock(tp->t_inpcb->inp_socket, 0, 0);
+               socket_unlock(tp->t_inpcb->inp_socket, 0);

                lck_rw_lock_exclusive(pcbinfo->ipi_lock);
                lck_rw_lock_exclusive(pcbinfo->ipi_lock);

-               tcp_lock(tp->t_inpcb->inp_socket, 0, 0);
+               socket_lock(tp->t_inpcb->inp_socket, 0);

        }
        add_to_time_wait_locked(tp, delay);
        lck_rw_done(pcbinfo->ipi_lock);
        }
        add_to_time_wait_locked(tp, delay);
        lck_rw_done(pcbinfo->ipi_lock);


@@ -366,20 +558,43 @@ void
 tcp_remove_from_time_wait(struct inpcb *inp)
 {
        struct tcpcb *tp = intotcpcb(inp);
 tcp_remove_from_time_wait(struct inpcb *inp)
 {
        struct tcpcb *tp = intotcpcb(inp);

-       if (inp->inp_flags2 & INP2_TIMEWAIT)
+       if (inp->inp_flags2 & INP2_TIMEWAIT) {

                TAILQ_REMOVE(&tcp_tw_tailq, tp, t_twentry);
                TAILQ_REMOVE(&tcp_tw_tailq, tp, t_twentry);

+       }

 }
 
 static boolean_t
 tcp_garbage_collect(struct inpcb *inp, int istimewait)
 {
        boolean_t active = FALSE;
 }
 
 static boolean_t
 tcp_garbage_collect(struct inpcb *inp, int istimewait)
 {
        boolean_t active = FALSE;

-       struct socket *so;
+       struct socket *so, *mp_so = NULL;

        struct tcpcb *tp;
 
        so = inp->inp_socket;
        tp = intotcpcb(inp);
 
        struct tcpcb *tp;
 
        so = inp->inp_socket;
        tp = intotcpcb(inp);
 

+       if (so->so_flags & SOF_MP_SUBFLOW) {
+               mp_so = mptetoso(tptomptp(tp)->mpt_mpte);
+               if (!socket_try_lock(mp_so)) {
+                       mp_so = NULL;
+                       active = TRUE;
+                       goto out;
+               }
+               if (mpsotomppcb(mp_so)->mpp_inside > 0) {
+                       os_log(mptcp_log_handle, "%s - %lx: Still inside %d usecount %d\n", __func__,
+                           (unsigned long)VM_KERNEL_ADDRPERM(mpsotompte(mp_so)),
+                           mpsotomppcb(mp_so)->mpp_inside,
+                           mp_so->so_usecount);
+                       socket_unlock(mp_so, 0);
+                       mp_so = NULL;
+                       active = TRUE;
+                       goto out;
+               }
+               /* We call socket_unlock with refcount further below */
+               mp_so->so_usecount++;
+               tptomptp(tp)->mpt_mpte->mpte_mppcb->mpp_inside++;
+       }
+

        /*
         * Skip if still in use or busy; it would have been more efficient
         * if we were to test so_usecount against 0, but this isn't possible
        /*
         * Skip if still in use or busy; it would have been more efficient
         * if we were to test so_usecount against 0, but this isn't possible


@@ -387,20 +602,22 @@ tcp_garbage_collect(struct inpcb *inp, int istimewait)
         * overflow sockets that are eligible for garbage collection have
         * their usecounts set to 1.
         */
         * overflow sockets that are eligible for garbage collection have
         * their usecounts set to 1.
         */

-       if (!lck_mtx_try_lock_spin(&inp->inpcb_mtx))
-               return (TRUE);
+       if (!lck_mtx_try_lock_spin(&inp->inpcb_mtx)) {
+               active = TRUE;
+               goto out;
+       }

 
        /* Check again under the lock */
        if (so->so_usecount > 1) {
 
        /* Check again under the lock */
        if (so->so_usecount > 1) {

-               if (inp->inp_wantcnt == WNT_STOPUSING)
+               if (inp->inp_wantcnt == WNT_STOPUSING) {

                        active = TRUE;
                        active = TRUE;

+               }

                lck_mtx_unlock(&inp->inpcb_mtx);
                lck_mtx_unlock(&inp->inpcb_mtx);

-               return (active);
+               goto out;

        }
 
        }
 

-       if (istimewait &&
-               TSTMP_GEQ(tcp_now, tp->t_timer[TCPT_2MSL]) &&
-               tp->t_state != TCPS_CLOSED) {
+       if (istimewait && TSTMP_GEQ(tcp_now, tp->t_timer[TCPT_2MSL]) &&
+           tp->t_state != TCPS_CLOSED) {

                /* Become a regular mutex */
                lck_mtx_convert_spin(&inp->inpcb_mtx);
                tcp_close(tp);
                /* Become a regular mutex */
                lck_mtx_convert_spin(&inp->inpcb_mtx);
                tcp_close(tp);


@@ -419,48 +636,49 @@ tcp_garbage_collect(struct inpcb *inp, int istimewait)
            ((istimewait && (so->so_flags & SOF_OVERFLOW)) ||
            ((tp != NULL) && (tp->t_state == TCPS_CLOSED) &&
            (so->so_head != NULL) &&
            ((istimewait && (so->so_flags & SOF_OVERFLOW)) ||
            ((tp != NULL) && (tp->t_state == TCPS_CLOSED) &&
            (so->so_head != NULL) &&

-           ((so->so_state & (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE)) ==
-           (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE))))) {
-
+           ((so->so_state & (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE)) ==
+           (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE))))) {

                if (inp->inp_state != INPCB_STATE_DEAD) {
                        /* Become a regular mutex */
                        lck_mtx_convert_spin(&inp->inpcb_mtx);
                if (inp->inp_state != INPCB_STATE_DEAD) {
                        /* Become a regular mutex */
                        lck_mtx_convert_spin(&inp->inpcb_mtx);

-#if INET6
-                       if (SOCK_CHECK_DOM(so, PF_INET6))
+                       if (SOCK_CHECK_DOM(so, PF_INET6)) {

                                in6_pcbdetach(inp);
                                in6_pcbdetach(inp);

-                       else
-#endif /* INET6 */
+                       } else {

                                in_pcbdetach(inp);
                                in_pcbdetach(inp);

+                       }

                }
                }

+               VERIFY(so->so_usecount > 0);

                so->so_usecount--;
                so->so_usecount--;

-               if (inp->inp_wantcnt == WNT_STOPUSING)
+               if (inp->inp_wantcnt == WNT_STOPUSING) {

                        active = TRUE;
                        active = TRUE;

+               }

                lck_mtx_unlock(&inp->inpcb_mtx);
                lck_mtx_unlock(&inp->inpcb_mtx);

-               return (active);
+               goto out;

        } else if (inp->inp_wantcnt != WNT_STOPUSING) {
                lck_mtx_unlock(&inp->inpcb_mtx);
        } else if (inp->inp_wantcnt != WNT_STOPUSING) {
                lck_mtx_unlock(&inp->inpcb_mtx);

-               return (FALSE);
+               active = FALSE;
+               goto out;

        }
 
        /*
        }
 
        /*

-        * We get here because the PCB is no longer searchable 
-        * (WNT_STOPUSING); detach (if needed) and dispose if it is dead 
-        * (usecount is 0).  This covers all cases, including overflow 
-        * sockets and those that are considered as "embryonic", 
-        * i.e. created by sonewconn() in TCP input path, and have 
+        * We get here because the PCB is no longer searchable
+        * (WNT_STOPUSING); detach (if needed) and dispose if it is dead
+        * (usecount is 0).  This covers all cases, including overflow
+        * sockets and those that are considered as "embryonic",
+        * i.e. created by sonewconn() in TCP input path, and have

         * not yet been committed.  For the former, we reduce the usecount
         * not yet been committed.  For the former, we reduce the usecount

-        *  to 0 as done by the code above.  For the latter, the usecount 
+        *  to 0 as done by the code above.  For the latter, the usecount

         * would have reduced to 0 as part calling soabort() when the
         * socket is dropped at the end of tcp_input().
         */
        if (so->so_usecount == 0) {
                DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
         * would have reduced to 0 as part calling soabort() when the
         * socket is dropped at the end of tcp_input().
         */
        if (so->so_usecount == 0) {
                DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,

-                       struct tcpcb *, tp, int32_t, TCPS_CLOSED);
+                   struct tcpcb *, tp, int32_t, TCPS_CLOSED);

                /* Become a regular mutex */
                lck_mtx_convert_spin(&inp->inpcb_mtx);
 
                /*
                /* Become a regular mutex */
                lck_mtx_convert_spin(&inp->inpcb_mtx);
 
                /*

-                * If this tp still happens to be on the timer list, 
+                * If this tp still happens to be on the timer list,

                 * take it out
                 */
                if (TIMER_IS_ON_LIST(tp)) {
                 * take it out
                 */
                if (TIMER_IS_ON_LIST(tp)) {


@@ -468,19 +686,35 @@ tcp_garbage_collect(struct inpcb *inp, int istimewait)
                }
 
                if (inp->inp_state != INPCB_STATE_DEAD) {
                }
 
                if (inp->inp_state != INPCB_STATE_DEAD) {

-#if INET6
-                       if (SOCK_CHECK_DOM(so, PF_INET6))
+                       if (SOCK_CHECK_DOM(so, PF_INET6)) {

                                in6_pcbdetach(inp);
                                in6_pcbdetach(inp);

-                       else
-#endif /* INET6 */
+                       } else {

                                in_pcbdetach(inp);
                                in_pcbdetach(inp);

+                       }
+               }
+
+               if (mp_so) {
+                       mptcp_subflow_del(tptomptp(tp)->mpt_mpte, tp->t_mpsub);
+
+                       /* so is now unlinked from mp_so - let's drop the lock */
+                       socket_unlock(mp_so, 1);
+                       mp_so = NULL;

                }
                }

+

                in_pcbdispose(inp);
                in_pcbdispose(inp);

-               return (FALSE);
+               active = FALSE;
+               goto out;

        }
 
        lck_mtx_unlock(&inp->inpcb_mtx);
        }
 
        lck_mtx_unlock(&inp->inpcb_mtx);

-       return (TRUE);
+       active = TRUE;
+
+out:
+       if (mp_so) {
+               socket_unlock(mp_so, 1);
+       }
+
+       return active;

 }
 
 /*
 }
 
 /*


@@ -530,26 +764,28 @@ tcp_gc(struct inpcbinfo *ipi)
        tcp_gc_done = TRUE;
 
        LIST_FOREACH_SAFE(inp, &tcb, inp_list, nxt) {
        tcp_gc_done = TRUE;
 
        LIST_FOREACH_SAFE(inp, &tcb, inp_list, nxt) {

-               if (tcp_garbage_collect(inp, 0))
+               if (tcp_garbage_collect(inp, 0)) {

                        atomic_add_32(&ipi->ipi_gc_req.intimer_fast, 1);
                        atomic_add_32(&ipi->ipi_gc_req.intimer_fast, 1);

+               }

        }
 
        /* Now cleanup the time wait ones */
        TAILQ_FOREACH_SAFE(tw_tp, &tcp_tw_tailq, t_twentry, tw_ntp) {
                /*
        }
 
        /* Now cleanup the time wait ones */
        TAILQ_FOREACH_SAFE(tw_tp, &tcp_tw_tailq, t_twentry, tw_ntp) {
                /*

-                * We check the timestamp here without holding the 
+                * We check the timestamp here without holding the

                 * socket lock for better performance. If there are
                 * any pcbs in time-wait, the timer will get rescheduled.
                 * Hence some error in this check can be tolerated.
                 *
                 * Sometimes a socket on time-wait queue can be closed if
                 * 2MSL timer expired but the application still has a
                 * socket lock for better performance. If there are
                 * any pcbs in time-wait, the timer will get rescheduled.
                 * Hence some error in this check can be tolerated.
                 *
                 * Sometimes a socket on time-wait queue can be closed if
                 * 2MSL timer expired but the application still has a

-                * usecount on it. 
+                * usecount on it.

                 */
                 */

-               if (tw_tp->t_state == TCPS_CLOSED ||  
+               if (tw_tp->t_state == TCPS_CLOSED ||

                    TSTMP_GEQ(tcp_now, tw_tp->t_timer[TCPT_2MSL])) {
                    TSTMP_GEQ(tcp_now, tw_tp->t_timer[TCPT_2MSL])) {

-                       if (tcp_garbage_collect(tw_tp->t_inpcb, 1))
+                       if (tcp_garbage_collect(tw_tp->t_inpcb, 1)) {

                                atomic_add_32(&ipi->ipi_gc_req.intimer_lazy, 1);
                                atomic_add_32(&ipi->ipi_gc_req.intimer_lazy, 1);

+                       }

                }
        }
 
                }
        }
 


@@ -559,8 +795,9 @@ tcp_gc(struct inpcbinfo *ipi)
        lck_rw_done(ipi->ipi_lock);
 
        /* Clean up the socache while we are here */
        lck_rw_done(ipi->ipi_lock);
 
        /* Clean up the socache while we are here */

-       if (so_cache_timer())
+       if (so_cache_timer()) {

                atomic_add_32(&ipi->ipi_gc_req.intimer_lazy, 1);
                atomic_add_32(&ipi->ipi_gc_req.intimer_lazy, 1);

+       }

 
        KERNEL_DEBUG(DBG_FNC_TCP_SLOW | DBG_FUNC_END, tws_checked,
            cur_tw_slot, 0, 0, 0);
 
        KERNEL_DEBUG(DBG_FNC_TCP_SLOW | DBG_FUNC_END, tws_checked,
            cur_tw_slot, 0, 0, 0);


@@ -572,32 +809,33 @@ tcp_gc(struct inpcbinfo *ipi)
  * Cancel all timers for TCP tp.
  */
 void
  * Cancel all timers for TCP tp.
  */
 void

-tcp_canceltimers(tp)
-       struct tcpcb *tp;
+tcp_canceltimers(struct tcpcb *tp)

 {
 {

-       register int i;
+       int i;

 
        tcp_remove_timer(tp);
 
        tcp_remove_timer(tp);

-       for (i = 0; i < TCPT_NTIMERS; i++)
+       for (i = 0; i < TCPT_NTIMERS; i++) {

                tp->t_timer[i] = 0;
                tp->t_timer[i] = 0;

+       }

        tp->tentry.timer_start = tcp_now;
        tp->tentry.index = TCPT_NONE;
 }
 
        tp->tentry.timer_start = tcp_now;
        tp->tentry.index = TCPT_NONE;
 }
 

-int    tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
-    { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
+int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
+{ 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };

 
 

-int    tcp_backoff[TCP_MAXRXTSHIFT + 1] =
-    { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
+int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
+{ 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };

 
 

-static int tcp_totbackoff = 511;       /* sum of tcp_backoff[] */
+static int tcp_totbackoff = 511;        /* sum of tcp_backoff[] */

 
 

-static void tcp_rexmt_save_state(struct tcpcb *tp)
+void
+tcp_rexmt_save_state(struct tcpcb *tp)

 {
        u_int32_t fsize;
        if (TSTMP_SUPPORTED(tp)) {
                /*
 {
        u_int32_t fsize;
        if (TSTMP_SUPPORTED(tp)) {
                /*

-                * Since timestamps are supported on the connection, 
+                * Since timestamps are supported on the connection,

                 * we can do recovery as described in rfc 4015.
                 */
                fsize = tp->snd_max - tp->snd_una;
                 * we can do recovery as described in rfc 4015.
                 */
                fsize = tp->snd_max - tp->snd_una;


@@ -608,19 +846,20 @@ static void tcp_rexmt_save_state(struct tcpcb *tp)
                 * Timestamp option is not supported on this connection.
                 * Record ssthresh and cwnd so they can
                 * be recovered if this turns out to be a "bad" retransmit.
                 * Timestamp option is not supported on this connection.
                 * Record ssthresh and cwnd so they can
                 * be recovered if this turns out to be a "bad" retransmit.

-                * A retransmit is considered "bad" if an ACK for this 
+                * A retransmit is considered "bad" if an ACK for this

                 * segment is received within RTT/2 interval; the assumption
                 * segment is received within RTT/2 interval; the assumption

-                * here is that the ACK was already in flight.  See 
+                * here is that the ACK was already in flight.  See

                 * "On Estimating End-to-End Network Path Properties" by
                 * Allman and Paxson for more details.
                 */
                tp->snd_cwnd_prev = tp->snd_cwnd;
                tp->snd_ssthresh_prev = tp->snd_ssthresh;
                tp->snd_recover_prev = tp->snd_recover;
                 * "On Estimating End-to-End Network Path Properties" by
                 * Allman and Paxson for more details.
                 */
                tp->snd_cwnd_prev = tp->snd_cwnd;
                tp->snd_ssthresh_prev = tp->snd_ssthresh;
                tp->snd_recover_prev = tp->snd_recover;

-               if (IN_FASTRECOVERY(tp))
+               if (IN_FASTRECOVERY(tp)) {

                        tp->t_flags |= TF_WASFRECOVERY;
                        tp->t_flags |= TF_WASFRECOVERY;

-               else
+               } else {

                        tp->t_flags &= ~TF_WASFRECOVERY;
                        tp->t_flags &= ~TF_WASFRECOVERY;

+               }

        }
        tp->t_srtt_prev = (tp->t_srtt >> TCP_RTT_SHIFT) + 2;
        tp->t_rttvar_prev = (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
        }
        tp->t_srtt_prev = (tp->t_srtt >> TCP_RTT_SHIFT) + 2;
        tp->t_rttvar_prev = (tp->t_rttvar >> TCP_RTTVAR_SHIFT);


@@ -631,33 +870,52 @@ static void tcp_rexmt_save_state(struct tcpcb *tp)
  * Revert to the older segment size if there is an indication that PMTU
  * blackhole detection was not needed.
  */
  * Revert to the older segment size if there is an indication that PMTU
  * blackhole detection was not needed.
  */

-void tcp_pmtud_revert_segment_size(struct tcpcb *tp)
+void
+tcp_pmtud_revert_segment_size(struct tcpcb *tp)

 {
        int32_t optlen;
 
        VERIFY(tp->t_pmtud_saved_maxopd > 0);
 {
        int32_t optlen;
 
        VERIFY(tp->t_pmtud_saved_maxopd > 0);

-       tp->t_flags |= TF_PMTUD; 
-       tp->t_flags &= ~TF_BLACKHOLE; 
+       tp->t_flags |= TF_PMTUD;
+       tp->t_flags &= ~TF_BLACKHOLE;

        optlen = tp->t_maxopd - tp->t_maxseg;
        tp->t_maxopd = tp->t_pmtud_saved_maxopd;
        tp->t_maxseg = tp->t_maxopd - optlen;
        optlen = tp->t_maxopd - tp->t_maxseg;
        tp->t_maxopd = tp->t_pmtud_saved_maxopd;
        tp->t_maxseg = tp->t_maxopd - optlen;

+

        /*
        /*

-        * Reset the slow-start flight size as it 
+        * Reset the slow-start flight size as it

         * may depend on the new MSS
         */
         * may depend on the new MSS
         */

-       if (CC_ALGO(tp)->cwnd_init != NULL)
+       if (CC_ALGO(tp)->cwnd_init != NULL) {

                CC_ALGO(tp)->cwnd_init(tp);
                CC_ALGO(tp)->cwnd_init(tp);

+       }

        tp->t_pmtud_start_ts = 0;
        tcpstat.tcps_pmtudbh_reverted++;
        tp->t_pmtud_start_ts = 0;
        tcpstat.tcps_pmtudbh_reverted++;

+
+       /* change MSS according to recommendation, if there was one */
+       tcp_update_mss_locked(tp->t_inpcb->inp_socket, NULL);
+}
+
+static uint32_t
+tcp_pmtud_black_holed_next_mss(struct tcpcb *tp)
+{
+       /* Reduce the MSS to intermediary value */
+       if (tp->t_maxopd > tcp_pmtud_black_hole_mss) {
+               return tcp_pmtud_black_hole_mss;
+       } else {
+               if (tp->t_inpcb->inp_vflag & INP_IPV4) {
+                       return tcp_mssdflt;
+               } else {
+                       return tcp_v6mssdflt;
+               }
+       }

 }
 
 /*
  * TCP timer processing.
  */
 struct tcpcb *
 }
 
 /*
  * TCP timer processing.
  */
 struct tcpcb *

-tcp_timers(tp, timer)
-       register struct tcpcb *tp;
-       int timer;
+tcp_timers(struct tcpcb *tp, int timer)

 {
        int32_t rexmt, optlen = 0, idle_time = 0;
        struct socket *so;
 {
        int32_t rexmt, optlen = 0, idle_time = 0;
        struct socket *so;


@@ -665,16 +923,13 @@ tcp_timers(tp, timer)
 #if TCPDEBUG
        int ostate;
 #endif
 #if TCPDEBUG
        int ostate;
 #endif

-
-#if INET6
-       int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV4) == 0;
-#endif /* INET6 */
+       u_int64_t accsleep_ms;
+       u_int64_t last_sleep_ms = 0;

 
        so = tp->t_inpcb->inp_socket;
        idle_time = tcp_now - tp->t_rcvtime;
 
        switch (timer) {
 
        so = tp->t_inpcb->inp_socket;
        idle_time = tcp_now - tp->t_rcvtime;
 
        switch (timer) {

-

        /*
         * 2 MSL timeout in shutdown went off.  If we're closed but
         * still waiting for peer to close and connection has been idle
        /*
         * 2 MSL timeout in shutdown went off.  If we're closed but
         * still waiting for peer to close and connection has been idle


@@ -688,11 +943,11 @@ tcp_timers(tp, timer)
                if (tp->t_state != TCPS_TIME_WAIT &&
                    tp->t_state != TCPS_FIN_WAIT_2 &&
                    ((idle_time > 0) && (idle_time < TCP_CONN_MAXIDLE(tp)))) {
                if (tp->t_state != TCPS_TIME_WAIT &&
                    tp->t_state != TCPS_FIN_WAIT_2 &&
                    ((idle_time > 0) && (idle_time < TCP_CONN_MAXIDLE(tp)))) {

-                       tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp, 
-                               (u_int32_t)TCP_CONN_KEEPINTVL(tp));
+                       tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp,
+                           (u_int32_t)TCP_CONN_KEEPINTVL(tp));

                } else {
                        tp = tcp_close(tp);
                } else {
                        tp = tcp_close(tp);

-                       return(tp);
+                       return tp;

                }
                break;
 
                }
                break;
 


@@ -702,6 +957,12 @@ tcp_timers(tp, timer)
         * to a longer retransmit interval and retransmit one segment.
         */
        case TCPT_REXMT:
         * to a longer retransmit interval and retransmit one segment.
         */
        case TCPT_REXMT:

+               absolutetime_to_nanoseconds(mach_absolutetime_asleep,
+                   &accsleep_ms);
+               accsleep_ms = accsleep_ms / 1000000UL;
+               if (accsleep_ms > tp->t_accsleep_ms) {
+                       last_sleep_ms = accsleep_ms - tp->t_accsleep_ms;
+               }

                /*
                 * Drop a connection in the retransmit timer
                 * 1. If we have retransmitted more than TCP_MAXRXTSHIFT
                /*
                 * Drop a connection in the retransmit timer
                 * 1. If we have retransmitted more than TCP_MAXRXTSHIFT


@@ -714,57 +975,96 @@ tcp_timers(tp, timer)
                 * receiving an ack
                 */
                if (++tp->t_rxtshift > TCP_MAXRXTSHIFT ||
                 * receiving an ack
                 */
                if (++tp->t_rxtshift > TCP_MAXRXTSHIFT ||

-                   (tp->t_rxt_conndroptime > 0 
-                   && tp->t_rxtstart > 0 && 
-                   (tcp_now - tp->t_rxtstart) >= tp->t_rxt_conndroptime)
-                   || ((tp->t_flagsext & TF_RXTFINDROP) != 0 &&
-                       (tp->t_flags & TF_SENTFIN) != 0 &&
-                       tp->t_rxtshift >= 4)) {
+                   (tp->t_rxt_conndroptime > 0 && tp->t_rxtstart > 0 &&
+                   (tcp_now - tp->t_rxtstart) >= tp->t_rxt_conndroptime) ||
+                   ((tp->t_flagsext & TF_RXTFINDROP) != 0 &&
+                   (tp->t_flags & TF_SENTFIN) != 0 && tp->t_rxtshift >= 4) ||
+                   (tp->t_rxtshift > 4 && last_sleep_ms >= TCP_SLEEP_TOO_LONG)) {
+                       if (tp->t_state == TCPS_ESTABLISHED &&
+                           tp->t_rxt_minimum_timeout > 0) {
+                               /*
+                                * Avoid dropping a connection if minimum
+                                * timeout is set and that time did not
+                                * pass. We will retry sending
+                                * retransmissions at the maximum interval
+                                */
+                               if (TSTMP_LT(tcp_now, (tp->t_rxtstart +
+                                   tp->t_rxt_minimum_timeout))) {
+                                       tp->t_rxtshift = TCP_MAXRXTSHIFT - 1;
+                                       goto retransmit_packet;
+                               }
+                       }

                        if ((tp->t_flagsext & TF_RXTFINDROP) != 0) {
                                tcpstat.tcps_rxtfindrop++;
                        if ((tp->t_flagsext & TF_RXTFINDROP) != 0) {
                                tcpstat.tcps_rxtfindrop++;

+                       } else if (last_sleep_ms >= TCP_SLEEP_TOO_LONG) {
+                               tcpstat.tcps_drop_after_sleep++;

                        } else {
                                tcpstat.tcps_timeoutdrop++;
                        }
                        } else {
                                tcpstat.tcps_timeoutdrop++;
                        }

+                       if (tp->t_rxtshift >= TCP_MAXRXTSHIFT) {
+                               if (TCP_ECN_ENABLED(tp)) {
+                                       INP_INC_IFNET_STAT(tp->t_inpcb,
+                                           ecn_on.rxmit_drop);
+                               } else {
+                                       INP_INC_IFNET_STAT(tp->t_inpcb,
+                                           ecn_off.rxmit_drop);
+                               }
+                       }

                        tp->t_rxtshift = TCP_MAXRXTSHIFT;
                        tp->t_rxtshift = TCP_MAXRXTSHIFT;

-                       postevent(so, 0, EV_TIMEOUT);                   
-                       soevent(so, 
-                           (SO_FILT_HINT_LOCKED|SO_FILT_HINT_TIMEOUT));
+                       soevent(so,
+                           (SO_FILT_HINT_LOCKED | SO_FILT_HINT_TIMEOUT));
+
+                       if (TCP_ECN_ENABLED(tp) &&
+                           tp->t_state == TCPS_ESTABLISHED) {
+                               tcp_heuristic_ecn_droprxmt(tp);
+                       }
+

                        tp = tcp_drop(tp, tp->t_softerror ?
                            tp->t_softerror : ETIMEDOUT);
 
                        break;
                }
                        tp = tcp_drop(tp, tp->t_softerror ?
                            tp->t_softerror : ETIMEDOUT);
 
                        break;
                }

-
+retransmit_packet:

                tcpstat.tcps_rexmttimeo++;
                tcpstat.tcps_rexmttimeo++;

+               tp->t_accsleep_ms = accsleep_ms;

 
 

-               if (tp->t_rxtshift == 1 && 
-                       tp->t_state == TCPS_ESTABLISHED) {
+               if (tp->t_rxtshift == 1 &&
+                   tp->t_state == TCPS_ESTABLISHED) {

                        /* Set the time at which retransmission started. */
                        tp->t_rxtstart = tcp_now;
 
                        /* Set the time at which retransmission started. */
                        tp->t_rxtstart = tcp_now;
 

-                       /* 
+                       /*

                         * if this is the first retransmit timeout, save
                         * the state so that we can recover if the timeout
                         * is spurious.
                         * if this is the first retransmit timeout, save
                         * the state so that we can recover if the timeout
                         * is spurious.

-                        */ 
+                        */

                        tcp_rexmt_save_state(tp);
                        tcp_rexmt_save_state(tp);

+                       tcp_ccdbg_trace(tp, NULL, TCP_CC_FIRST_REXMT);

                }
 #if MPTCP
                if ((tp->t_rxtshift >= mptcp_fail_thresh) &&
                    (tp->t_state == TCPS_ESTABLISHED) &&
                    (tp->t_mpflags & TMPF_MPTCP_TRUE)) {
                        mptcp_act_on_txfail(so);
                }
 #if MPTCP
                if ((tp->t_rxtshift >= mptcp_fail_thresh) &&
                    (tp->t_state == TCPS_ESTABLISHED) &&
                    (tp->t_mpflags & TMPF_MPTCP_TRUE)) {
                        mptcp_act_on_txfail(so);

+               }
+
+               if (TCPS_HAVEESTABLISHED(tp->t_state) &&
+                   (so->so_flags & SOF_MP_SUBFLOW)) {
+                       struct mptses *mpte = tptomptp(tp)->mpt_mpte;

 
 

+                       if (mpte->mpte_svctype == MPTCP_SVCTYPE_HANDOVER) {
+                               mptcp_check_subflows_and_add(mpte);
+                       }

                }
 #endif /* MPTCP */
 
                if (tp->t_adaptive_wtimo > 0 &&
                }
 #endif /* MPTCP */
 
                if (tp->t_adaptive_wtimo > 0 &&

-                       tp->t_rxtshift > tp->t_adaptive_wtimo &&
-                       TCPS_HAVEESTABLISHED(tp->t_state)) {
+                   tp->t_rxtshift > tp->t_adaptive_wtimo &&
+                   TCPS_HAVEESTABLISHED(tp->t_state)) {

                        /* Send an event to the application */
                        soevent(so,
                        /* Send an event to the application */
                        soevent(so,

-                               (SO_FILT_HINT_LOCKED|
-                               SO_FILT_HINT_ADAPTIVE_WTIMO));
+                           (SO_FILT_HINT_LOCKED |
+                           SO_FILT_HINT_ADAPTIVE_WTIMO));

                }
 
                /*
                }
 
                /*


@@ -788,32 +1088,89 @@ tcp_timers(tp, timer)
                        tp->t_flagsext &= ~(TF_DELAY_RECOVERY);
                }
 
                        tp->t_flagsext &= ~(TF_DELAY_RECOVERY);
                }
 

+               if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) &&
+                   tp->t_state == TCPS_SYN_RECEIVED) {
+                       tcp_disable_tfo(tp);
+               }
+
+               if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) &&
+                   !(tp->t_tfo_flags & TFO_F_HEURISTIC_DONE) &&
+                   (tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) &&
+                   !(tp->t_tfo_flags & TFO_F_NO_SNDPROBING) &&
+                   ((tp->t_state != TCPS_SYN_SENT && tp->t_rxtshift > 1) ||
+                   tp->t_rxtshift > 4)) {
+                       /*
+                        * For regular retransmissions, a first one is being
+                        * done for tail-loss probe.
+                        * Thus, if rxtshift > 1, this means we have sent the segment
+                        * a total of 3 times.
+                        *
+                        * If we are in SYN-SENT state, then there is no tail-loss
+                        * probe thus we have to let rxtshift go up to 3.
+                        */
+                       tcp_heuristic_tfo_middlebox(tp);
+
+                       so->so_error = ENODATA;
+                       soevent(so,
+                           (SO_FILT_HINT_LOCKED | SO_FILT_HINT_MP_SUB_ERROR));
+                       sorwakeup(so);
+                       sowwakeup(so);
+
+                       tp->t_tfo_stats |= TFO_S_SEND_BLACKHOLE;
+                       tcpstat.tcps_tfo_sndblackhole++;
+               }
+
+               if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) &&
+                   !(tp->t_tfo_flags & TFO_F_HEURISTIC_DONE) &&
+                   (tp->t_tfo_stats & TFO_S_SYN_DATA_ACKED) &&
+                   tp->t_rxtshift > 3) {
+                       if (TSTMP_GT(tp->t_sndtime - 10 * TCP_RETRANSHZ, tp->t_rcvtime)) {
+                               tcp_heuristic_tfo_middlebox(tp);
+
+                               so->so_error = ENODATA;
+                               soevent(so,
+                                   (SO_FILT_HINT_LOCKED | SO_FILT_HINT_MP_SUB_ERROR));
+                               sorwakeup(so);
+                               sowwakeup(so);
+                       }
+               }
+

                if (tp->t_state == TCPS_SYN_SENT) {
                        rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift];
                        tp->t_stat.synrxtshift = tp->t_rxtshift;
                if (tp->t_state == TCPS_SYN_SENT) {
                        rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift];
                        tp->t_stat.synrxtshift = tp->t_rxtshift;

+                       tp->t_stat.rxmitsyns++;
+
+                       /* When retransmitting, disable TFO */
+                       if (tfo_enabled(tp) &&
+                           !(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE)) {
+                               tcp_disable_tfo(tp);
+                               tp->t_tfo_flags |= TFO_F_SYN_LOSS;
+                       }

                } else {
                        rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
                }
 
                } else {
                        rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
                }
 

-               TCPT_RANGESET(tp->t_rxtcur, rexmt,
-                       tp->t_rttmin, TCPTV_REXMTMAX, 
-                       TCP_ADD_REXMTSLOP(tp));
+               TCPT_RANGESET(tp->t_rxtcur, rexmt, tp->t_rttmin, TCPTV_REXMTMAX,
+                   TCP_ADD_REXMTSLOP(tp));

                tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur);
 
                tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur);
 

-               if (INP_WAIT_FOR_IF_FEEDBACK(tp->t_inpcb))
+               TCP_LOG_RTT_INFO(tp);
+
+               if (INP_WAIT_FOR_IF_FEEDBACK(tp->t_inpcb)) {

                        goto fc_output;
                        goto fc_output;

+               }

 
                tcp_free_sackholes(tp);
                /*
                 * Check for potential Path MTU Discovery Black Hole
                 */
                if (tcp_pmtud_black_hole_detect &&
 
                tcp_free_sackholes(tp);
                /*
                 * Check for potential Path MTU Discovery Black Hole
                 */
                if (tcp_pmtud_black_hole_detect &&

-                       !(tp->t_flagsext & TF_NOBLACKHOLE_DETECTION) &&
-                       (tp->t_state == TCPS_ESTABLISHED)) {
-                       if (((tp->t_flags & (TF_PMTUD|TF_MAXSEGSNT))
-                           == (TF_PMTUD|TF_MAXSEGSNT)) &&
-                                (tp->t_rxtshift == 2)) {
-                               /* 
+                   !(tp->t_flagsext & TF_NOBLACKHOLE_DETECTION) &&
+                   (tp->t_state == TCPS_ESTABLISHED)) {
+                       if ((tp->t_flags & TF_PMTUD) &&
+                           tp->t_pmtud_lastseg_size > tcp_pmtud_black_holed_next_mss(tp) &&
+                           tp->t_rxtshift == 2) {
+                               /*

                                 * Enter Path MTU Black-hole Detection mechanism:
                                 * - Disable Path MTU Discovery (IP "DF" bit).
                                 * - Reduce MTU to lower value than what we
                                 * Enter Path MTU Black-hole Detection mechanism:
                                 * - Disable Path MTU Discovery (IP "DF" bit).
                                 * - Reduce MTU to lower value than what we


@@ -827,26 +1184,21 @@ tcp_timers(tp, timer)
                                /* Keep track of previous MSS */
                                tp->t_pmtud_saved_maxopd = tp->t_maxopd;
                                tp->t_pmtud_start_ts = tcp_now;
                                /* Keep track of previous MSS */
                                tp->t_pmtud_saved_maxopd = tp->t_maxopd;
                                tp->t_pmtud_start_ts = tcp_now;

-                               if (tp->t_pmtud_start_ts == 0)
+                               if (tp->t_pmtud_start_ts == 0) {

                                        tp->t_pmtud_start_ts++;
                                        tp->t_pmtud_start_ts++;

-                               /* Reduce the MSS to intermediary value */
-                               if (tp->t_maxopd > tcp_pmtud_black_hole_mss) {
-                                       tp->t_maxopd = tcp_pmtud_black_hole_mss;
-                               } else {
-                                       tp->t_maxopd =  /* use the default MSS */
-#if INET6
-                                               isipv6 ? tcp_v6mssdflt :
-#endif /* INET6 */
-                                                       tcp_mssdflt;

                                }
                                }

+                               /* Reduce the MSS to intermediary value */
+                               tp->t_maxopd = tcp_pmtud_black_holed_next_mss(tp);

                                tp->t_maxseg = tp->t_maxopd - optlen;
 
                                /*
                                tp->t_maxseg = tp->t_maxopd - optlen;
 
                                /*

-                                * Reset the slow-start flight size 
+                                * Reset the slow-start flight size

                                 * as it may depend on the new MSS
                                 * as it may depend on the new MSS

-                                */
-                               if (CC_ALGO(tp)->cwnd_init != NULL)
+                                */
+                               if (CC_ALGO(tp)->cwnd_init != NULL) {

                                        CC_ALGO(tp)->cwnd_init(tp);
                                        CC_ALGO(tp)->cwnd_init(tp);

+                               }
+                               tp->snd_cwnd = tp->t_maxseg;

                        }
                        /*
                         * If further retransmissions are still
                        }
                        /*
                         * If further retransmissions are still


@@ -855,10 +1207,10 @@ tcp_timers(tp, timer)
                         * MSS and blackhole detection flags.
                         */
                        else {
                         * MSS and blackhole detection flags.
                         */
                        else {

-       

                                if ((tp->t_flags & TF_BLACKHOLE) &&
                                    (tp->t_rxtshift > 4)) {
                                        tcp_pmtud_revert_segment_size(tp);
                                if ((tp->t_flags & TF_BLACKHOLE) &&
                                    (tp->t_rxtshift > 4)) {
                                        tcp_pmtud_revert_segment_size(tp);

+                                       tp->snd_cwnd = tp->t_maxseg;

                                }
                        }
                }
                                }
                        }
                }


@@ -874,11 +1226,9 @@ tcp_timers(tp, timer)
                 * Do this only on non-local connections.
                 */
                if (tp->t_state == TCPS_SYN_SENT &&
                 * Do this only on non-local connections.
                 */
                if (tp->t_state == TCPS_SYN_SENT &&

-                   ((!(tp->t_flags & TF_LOCAL) &&
-                   tp->t_rxtshift == tcp_broken_peer_syn_rxmit_thres) ||
-                   ((tp->t_flags & TF_LOCAL) && 
-                   tp->t_rxtshift == tcp_broken_peer_syn_rxmit_thres_local)))
-                       tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_REQ_CC);
+                   tp->t_rxtshift == tcp_broken_peer_syn_rxmit_thres) {
+                       tp->t_flags &= ~(TF_REQ_SCALE | TF_REQ_TSTMP | TF_REQ_CC);
+               }

 
                /*
                 * If losing, let the lower level know and try for
 
                /*
                 * If losing, let the lower level know and try for


@@ -889,12 +1239,11 @@ tcp_timers(tp, timer)
                 * retransmit times until then.
                 */
                if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
                 * retransmit times until then.
                 */
                if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {

-#if INET6
-                       if (isipv6)
+                       if (!(tp->t_inpcb->inp_vflag & INP_IPV4)) {

                                in6_losing(tp->t_inpcb);
                                in6_losing(tp->t_inpcb);

-                       else
-#endif /* INET6 */
-                       in_losing(tp->t_inpcb);
+                       } else {
+                               in_losing(tp->t_inpcb);
+                       }

                        tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
                        tp->t_srtt = 0;
                }
                        tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
                        tp->t_srtt = 0;
                }


@@ -912,8 +1261,9 @@ tcp_timers(tp, timer)
                /* If timing a segment in this window, stop the timer */
                tp->t_rtttime = 0;
 
                /* If timing a segment in this window, stop the timer */
                tp->t_rtttime = 0;
 

-               if (!IN_FASTRECOVERY(tp) && tp->t_rxtshift == 1)
+               if (!IN_FASTRECOVERY(tp) && tp->t_rxtshift == 1) {

                        tcpstat.tcps_tailloss_rto++;
                        tcpstat.tcps_tailloss_rto++;

+               }

 
 
                /*
 
 
                /*


@@ -922,18 +1272,25 @@ tcp_timers(tp, timer)
                 * been retransmitted by way of the retransmission timer at
                 * least once, the value of ssthresh is held constant
                 */
                 * been retransmitted by way of the retransmission timer at
                 * least once, the value of ssthresh is held constant
                 */

-               if (tp->t_rxtshift == 1 && 
-                       CC_ALGO(tp)->after_timeout != NULL)
+               if (tp->t_rxtshift == 1 &&
+                   CC_ALGO(tp)->after_timeout != NULL) {

                        CC_ALGO(tp)->after_timeout(tp);
                        CC_ALGO(tp)->after_timeout(tp);

+                       /*
+                        * CWR notifications are to be sent on new data
+                        * right after Fast Retransmits and ECE
+                        * notification receipts.
+                        */
+                       if (TCP_ECN_ENABLED(tp)) {
+                               tp->ecn_flags |= TE_SENDCWR;
+                       }
+               }

 
                EXIT_FASTRECOVERY(tp);
 
 
                EXIT_FASTRECOVERY(tp);
 

-               /* CWR notifications are to be sent on new data right after
-                * RTOs, Fast Retransmits and ECE notification receipts.
-                */
-               if ((tp->ecn_flags & TE_ECN_ON) == TE_ECN_ON) {
-                       tp->ecn_flags |= TE_SENDCWR;
-               }
+               /* Exit cwnd non validated phase */
+               tp->t_flagsext &= ~TF_CWND_NONVALIDATED;
+
+

 fc_output:
                tcp_ccdbg_trace(tp, NULL, TCP_CC_REXMT_TIMEOUT);
 
 fc_output:
                tcp_ccdbg_trace(tp, NULL, TCP_CC_REXMT_TIMEOUT);
 


@@ -952,20 +1309,19 @@ fc_output:
                 * backoff, drop the connection if the idle time
                 * (no responses to probes) reaches the maximum
                 * backoff that we would use if retransmitting.
                 * backoff, drop the connection if the idle time
                 * (no responses to probes) reaches the maximum
                 * backoff that we would use if retransmitting.

-                * 
-                * Drop the connection if we reached the maximum allowed time for 
-                * Zero Window Probes without a non-zero update from the peer. 
+                *
+                * Drop the connection if we reached the maximum allowed time for
+                * Zero Window Probes without a non-zero update from the peer.

                 * See rdar://5805356
                 */
                if ((tp->t_rxtshift == TCP_MAXRXTSHIFT &&
                    (idle_time >= tcp_maxpersistidle ||
                 * See rdar://5805356
                 */
                if ((tp->t_rxtshift == TCP_MAXRXTSHIFT &&
                    (idle_time >= tcp_maxpersistidle ||

-                   idle_time >= TCP_REXMTVAL(tp) * tcp_totbackoff)) || 
-                   ((tp->t_persist_stop != 0) && 
-                       TSTMP_LEQ(tp->t_persist_stop, tcp_now))) {
+                   idle_time >= TCP_REXMTVAL(tp) * tcp_totbackoff)) ||
+                   ((tp->t_persist_stop != 0) &&
+                   TSTMP_LEQ(tp->t_persist_stop, tcp_now))) {

                        tcpstat.tcps_persistdrop++;
                        tcpstat.tcps_persistdrop++;

-                       postevent(so, 0, EV_TIMEOUT);

                        soevent(so,
                        soevent(so,

-                           (SO_FILT_HINT_LOCKED|SO_FILT_HINT_TIMEOUT));
+                           (SO_FILT_HINT_LOCKED | SO_FILT_HINT_TIMEOUT));

                        tp = tcp_drop(tp, ETIMEDOUT);
                        break;
                }
                        tp = tcp_drop(tp, ETIMEDOUT);
                        break;
                }


@@ -980,29 +1336,39 @@ fc_output:
         * or drop connection if idle for too long.
         */
        case TCPT_KEEP:
         * or drop connection if idle for too long.
         */
        case TCPT_KEEP:

+#if FLOW_DIVERT
+               if (tp->t_inpcb->inp_socket->so_flags & SOF_FLOW_DIVERT) {
+                       break;
+               }
+#endif /* FLOW_DIVERT */
+

                tcpstat.tcps_keeptimeo++;
 #if MPTCP
                /*
                 * Regular TCP connections do not send keepalives after closing
                 * MPTCP must not also, after sending Data FINs.
                 */
                tcpstat.tcps_keeptimeo++;
 #if MPTCP
                /*
                 * Regular TCP connections do not send keepalives after closing
                 * MPTCP must not also, after sending Data FINs.
                 */

-               struct mptcb *mp_tp = tp->t_mptcb;
+               struct mptcb *mp_tp = tptomptp(tp);

                if ((tp->t_mpflags & TMPF_MPTCP_TRUE) &&
                    (tp->t_state > TCPS_ESTABLISHED)) {
                        goto dropit;
                } else if (mp_tp != NULL) {
                if ((tp->t_mpflags & TMPF_MPTCP_TRUE) &&
                    (tp->t_state > TCPS_ESTABLISHED)) {
                        goto dropit;
                } else if (mp_tp != NULL) {

-                       if ((mptcp_ok_to_keepalive(mp_tp) == 0))
+                       if ((mptcp_ok_to_keepalive(mp_tp) == 0)) {

                                goto dropit;
                                goto dropit;

+                       }

                }
 #endif /* MPTCP */
                }
 #endif /* MPTCP */

-               if (tp->t_state < TCPS_ESTABLISHED)
+               if (tp->t_state < TCPS_ESTABLISHED) {

                        goto dropit;
                        goto dropit;

+               }

                if ((always_keepalive ||
                    (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ||
                if ((always_keepalive ||
                    (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ||

-                   (tp->t_flagsext & TF_DETECT_READSTALL)) &&
+                   (tp->t_flagsext & TF_DETECT_READSTALL) ||
+                   (tp->t_tfo_probe_state == TFO_PROBE_PROBING)) &&

                    (tp->t_state <= TCPS_CLOSING || tp->t_state == TCPS_FIN_WAIT_2)) {
                    (tp->t_state <= TCPS_CLOSING || tp->t_state == TCPS_FIN_WAIT_2)) {

-                       if (idle_time >= TCP_CONN_KEEPIDLE(tp) + TCP_CONN_MAXIDLE(tp))
+                       if (idle_time >= TCP_CONN_KEEPIDLE(tp) + TCP_CONN_MAXIDLE(tp)) {

                                goto dropit;
                                goto dropit;

+                       }

                        /*
                         * Send a packet designed to force a response
                         * if the peer is up and reachable:
                        /*
                         * Send a packet designed to force a response
                         * if the peer is up and reachable:


@@ -1024,43 +1390,95 @@ fc_output:
                                bzero(&tra, sizeof(tra));
                                tra.nocell = INP_NO_CELLULAR(inp);
                                tra.noexpensive = INP_NO_EXPENSIVE(inp);
                                bzero(&tra, sizeof(tra));
                                tra.nocell = INP_NO_CELLULAR(inp);
                                tra.noexpensive = INP_NO_EXPENSIVE(inp);

+                               tra.noconstrained = INP_NO_CONSTRAINED(inp);

                                tra.awdl_unrestricted = INP_AWDL_UNRESTRICTED(inp);
                                tra.awdl_unrestricted = INP_AWDL_UNRESTRICTED(inp);

-                               if (tp->t_inpcb->inp_flags & INP_BOUND_IF)
+                               tra.intcoproc_allowed = INP_INTCOPROC_ALLOWED(inp);
+                               tra.keep_alive = 1;
+                               if (tp->t_inpcb->inp_flags & INP_BOUND_IF) {

                                        tra.ifscope = tp->t_inpcb->inp_boundifp->if_index;
                                        tra.ifscope = tp->t_inpcb->inp_boundifp->if_index;

-                               else
+                               } else {

                                        tra.ifscope = IFSCOPE_NONE;
                                        tra.ifscope = IFSCOPE_NONE;

+                               }

                                tcp_respond(tp, t_template->tt_ipgen,
                                    &t_template->tt_t, (struct mbuf *)NULL,
                                    tp->rcv_nxt, tp->snd_una - 1, 0, &tra);
                                (void) m_free(dtom(t_template));
                                tcp_respond(tp, t_template->tt_ipgen,
                                    &t_template->tt_t, (struct mbuf *)NULL,
                                    tp->rcv_nxt, tp->snd_una - 1, 0, &tra);
                                (void) m_free(dtom(t_template));

-                               if (tp->t_flagsext & TF_DETECT_READSTALL)
+                               if (tp->t_flagsext & TF_DETECT_READSTALL) {

                                        tp->t_rtimo_probes++;
                                        tp->t_rtimo_probes++;

+                               }

                        }
                        }

+
+                       TCP_LOG_KEEP_ALIVE(tp, idle_time);
+

                        tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,
                        tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,

-                               TCP_CONN_KEEPINTVL(tp));
+                           TCP_CONN_KEEPINTVL(tp));

                } else {
                        tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,
                } else {
                        tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,

-                               TCP_CONN_KEEPIDLE(tp));
+                           TCP_CONN_KEEPIDLE(tp));

                }
                if (tp->t_flagsext & TF_DETECT_READSTALL) {
                }
                if (tp->t_flagsext & TF_DETECT_READSTALL) {

-                       /* 
+                       struct ifnet *outifp = tp->t_inpcb->inp_last_outifp;
+                       bool reenable_probe = false;
+                       /*

                         * The keep alive packets sent to detect a read
                         * The keep alive packets sent to detect a read

-                        * stall did not get a response from the 
+                        * stall did not get a response from the

                         * peer. Generate more keep-alives to confirm this.
                         * If the number of probes sent reaches the limit,
                         * generate an event.
                         */
                         * peer. Generate more keep-alives to confirm this.
                         * If the number of probes sent reaches the limit,
                         * generate an event.
                         */

-                       if (tp->t_rtimo_probes > tp->t_adaptive_rtimo) {
-                               /* Generate an event */
-                               soevent(so,
-                                       (SO_FILT_HINT_LOCKED|
-                                       SO_FILT_HINT_ADAPTIVE_RTIMO));
-                               tcp_keepalive_reset(tp);
+                       if (tp->t_adaptive_rtimo > 0) {
+                               if (tp->t_rtimo_probes > tp->t_adaptive_rtimo) {
+                                       /* Generate an event */
+                                       soevent(so,
+                                           (SO_FILT_HINT_LOCKED |
+                                           SO_FILT_HINT_ADAPTIVE_RTIMO));
+                                       tcp_keepalive_reset(tp);
+                               } else {
+                                       reenable_probe = true;
+                               }
+                       } else if (outifp != NULL &&
+                           (outifp->if_eflags & IFEF_PROBE_CONNECTIVITY) &&
+                           tp->t_rtimo_probes <= TCP_CONNECTIVITY_PROBES_MAX) {
+                               reenable_probe = true;

                        } else {
                        } else {

+                               tp->t_flagsext &= ~TF_DETECT_READSTALL;
+                       }
+                       if (reenable_probe) {
+                               int ind = min(tp->t_rtimo_probes,
+                                   TCP_MAXRXTSHIFT);

                                tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(
                                tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(

-                                       tp, TCP_REXMTVAL(tp));
+                                       tp, tcp_backoff[ind] * TCP_REXMTVAL(tp));

                        }
                }
                        }
                }

+               if (tp->t_tfo_probe_state == TFO_PROBE_PROBING) {
+                       int ind;
+
+                       tp->t_tfo_probes++;
+                       ind = min(tp->t_tfo_probes, TCP_MAXRXTSHIFT);
+
+                       /*
+                        * We take the minimum among the time set by true
+                        * keepalive (see above) and the backoff'd RTO. That
+                        * way we backoff in case of packet-loss but will never
+                        * timeout slower than regular keepalive due to the
+                        * backing off.
+                        */
+                       tp->t_timer[TCPT_KEEP] = min(OFFSET_FROM_START(
+                                   tp, tcp_backoff[ind] * TCP_REXMTVAL(tp)),
+                           tp->t_timer[TCPT_KEEP]);
+               } else if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) &&
+                   !(tp->t_tfo_flags & TFO_F_HEURISTIC_DONE) &&
+                   tp->t_tfo_probe_state == TFO_PROBE_WAIT_DATA) {
+                       /* Still no data! Let's assume a TFO-error and err out... */
+                       tcp_heuristic_tfo_middlebox(tp);
+
+                       so->so_error = ENODATA;
+                       soevent(so,
+                           (SO_FILT_HINT_LOCKED | SO_FILT_HINT_MP_SUB_ERROR));
+                       sorwakeup(so);
+                       tp->t_tfo_stats |= TFO_S_RECV_BLACKHOLE;
+                       tcpstat.tcps_tfo_blackhole++;
+               }

                break;
        case TCPT_DELACK:
                if (tcp_delack_enabled && (tp->t_flags & TF_DELACK)) {
                break;
        case TCPT_DELACK:
                if (tcp_delack_enabled && (tp->t_flags & TF_DELACK)) {


@@ -1071,7 +1489,7 @@ fc_output:
                        /*
                         * If delayed ack timer fired while stretching
                         * acks, count the number of times the streaming
                        /*
                         * If delayed ack timer fired while stretching
                         * acks, count the number of times the streaming

-                        * detection was not correct. If this exceeds a 
+                        * detection was not correct. If this exceeds a

                         * threshold, disable strech ack on this
                         * connection
                         *
                         * threshold, disable strech ack on this
                         * connection
                         *


@@ -1079,11 +1497,12 @@ fc_output:
                         */
                        if ((tp->t_flags & TF_STRETCHACK)) {
                                if (tp->t_unacksegs > 1 &&
                         */
                        if ((tp->t_flags & TF_STRETCHACK)) {
                                if (tp->t_unacksegs > 1 &&

-                                   tp->t_unacksegs < maxseg_unacked)
+                                   tp->t_unacksegs < maxseg_unacked) {

                                        tp->t_stretchack_delayed++;
                                        tp->t_stretchack_delayed++;

+                               }

 
                                if (tp->t_stretchack_delayed >
 
                                if (tp->t_stretchack_delayed >

-                                       TCP_STRETCHACK_DELAY_THRESHOLD) {
+                                   TCP_STRETCHACK_DELAY_THRESHOLD) {

                                        tp->t_flagsext |= TF_DISABLE_STRETCHACK;
                                        /*
                                         * Note the time at which stretch
                                        tp->t_flagsext |= TF_DISABLE_STRETCHACK;
                                        /*
                                         * Note the time at which stretch


@@ -1092,9 +1511,11 @@ fc_output:
                                        tp->rcv_nostrack_ts = tcp_now;
                                        tcpstat.tcps_nostretchack++;
                                        tp->t_stretchack_delayed = 0;
                                        tp->rcv_nostrack_ts = tcp_now;
                                        tcpstat.tcps_nostretchack++;
                                        tp->t_stretchack_delayed = 0;

+                                       tp->rcv_nostrack_pkts = 0;

                                }
                                tcp_reset_stretch_ack(tp);
                        }
                                }
                                tcp_reset_stretch_ack(tp);
                        }

+                       tp->t_forced_acks = TCP_FORCED_ACKS_COUNT;

 
                        /*
                         * If we are measuring inter packet arrival jitter
 
                        /*
                         * If we are measuring inter packet arrival jitter


@@ -1105,6 +1526,7 @@ fc_output:
                        CLEAR_IAJ_STATE(tp);
 
                        tcpstat.tcps_delack++;
                        CLEAR_IAJ_STATE(tp);
 
                        tcpstat.tcps_delack++;

+                       tp->t_stat.delayed_acks_sent++;

                        (void) tcp_output(tp);
                }
                break;
                        (void) tcp_output(tp);
                }
                break;


@@ -1116,66 +1538,113 @@ fc_output:
                    (tp->t_mpflags & TMPF_JOINED_FLOW)) {
                        if (++tp->t_mprxtshift > TCP_MAXRXTSHIFT) {
                                tcpstat.tcps_timeoutdrop++;
                    (tp->t_mpflags & TMPF_JOINED_FLOW)) {
                        if (++tp->t_mprxtshift > TCP_MAXRXTSHIFT) {
                                tcpstat.tcps_timeoutdrop++;

-                               postevent(so, 0, EV_TIMEOUT);
-                               soevent(so, 
-                                   (SO_FILT_HINT_LOCKED|
+                               soevent(so,
+                                   (SO_FILT_HINT_LOCKED |

                                    SO_FILT_HINT_TIMEOUT));
                                tp = tcp_drop(tp, tp->t_softerror ?
                                    SO_FILT_HINT_TIMEOUT));
                                tp = tcp_drop(tp, tp->t_softerror ?

-                                   tp->t_softerror : ETIMEDOUT);
+                                   tp->t_softerror : ETIMEDOUT);

                                break;
                        }
                        tcpstat.tcps_join_rxmts++;
                                break;
                        }
                        tcpstat.tcps_join_rxmts++;

+                       tp->t_mpflags |= TMPF_SND_JACK;

                        tp->t_flags |= TF_ACKNOW;
 
                        /*
                        tp->t_flags |= TF_ACKNOW;
 
                        /*

-                        * No backoff is implemented for simplicity for this 
+                        * No backoff is implemented for simplicity for this

                         * corner case.
                         */
                        (void) tcp_output(tp);
                }
                break;
                         * corner case.
                         */
                        (void) tcp_output(tp);
                }
                break;

+       case TCPT_CELLICON:
+       {
+               struct mptses *mpte = tptomptp(tp)->mpt_mpte;
+
+               tp->t_timer[TCPT_CELLICON] = 0;
+
+               if (mpte->mpte_cellicon_increments == 0) {
+                       /* Cell-icon not set by this connection */
+                       break;
+               }
+
+               if (TSTMP_LT(mpte->mpte_last_cellicon_set + MPTCP_CELLICON_TOGGLE_RATE, tcp_now)) {
+                       mptcp_unset_cellicon(mpte, NULL, 1);
+               }
+
+               if (mpte->mpte_cellicon_increments) {
+                       tp->t_timer[TCPT_CELLICON] = OFFSET_FROM_START(tp, MPTCP_CELLICON_TOGGLE_RATE);
+               }
+
+               break;
+       }

 #endif /* MPTCP */
 
        case TCPT_PTO:
        {
 #endif /* MPTCP */
 
        case TCPT_PTO:
        {

-               tcp_seq old_snd_nxt;
-               int32_t snd_len;
-               boolean_t rescue_rxt = FALSE;
-
-               tp->t_flagsext &= ~(TF_SENT_TLPROBE);
+               int32_t ret = 0;

 
 

+               if (!(tp->t_flagsext & TF_IF_PROBING)) {
+                       tp->t_flagsext &= ~(TF_SENT_TLPROBE);
+               }

                /*
                 * Check if the connection is in the right state to
                 * send a probe
                 */
                /*
                 * Check if the connection is in the right state to
                 * send a probe
                 */

-               if (tp->t_state != TCPS_ESTABLISHED ||
-                   tp->t_rxtshift > 0 || tp->snd_max == tp->snd_una ||
-                   !SACK_ENABLED(tp) || TAILQ_EMPTY(&tp->snd_holes) ||
-                   (IN_FASTRECOVERY(tp) &&
-                   (SEQ_GEQ(tp->snd_fack, tp->snd_recover) ||
-                   SEQ_GT(tp->snd_nxt, tp->sack_newdata))))
+               if ((tp->t_state != TCPS_ESTABLISHED ||
+                   tp->t_rxtshift > 0 ||
+                   tp->snd_max == tp->snd_una ||
+                   !SACK_ENABLED(tp) ||
+                   (tcp_do_better_lr != 1 && !TAILQ_EMPTY(&tp->snd_holes)) ||
+                   IN_FASTRECOVERY(tp)) &&
+                   !(tp->t_flagsext & TF_IF_PROBING)) {

                        break;
                        break;

+               }

 
 

-               tcpstat.tcps_pto++;
-
-               /* If timing a segment in this window, stop the timer */
-               tp->t_rtttime = 0;
+               /*
+                * When the interface state is changed explicitly reset the retransmission
+                * timer state for both SYN and data packets because we do not want to
+                * wait unnecessarily or timeout too quickly if the link characteristics
+                * have changed drastically
+                */
+               if (tp->t_flagsext & TF_IF_PROBING) {
+                       tp->t_rxtshift = 0;
+                       if (tp->t_state == TCPS_SYN_SENT) {
+                               tp->t_stat.synrxtshift = tp->t_rxtshift;
+                       }
+                       /*
+                        * Reset to the the default RTO
+                        */
+                       tp->t_srtt = TCPTV_SRTTBASE;
+                       tp->t_rttvar =
+                           ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
+                       tp->t_rttmin = tp->t_flags & TF_LOCAL ? tcp_TCPTV_MIN :
+                           TCPTV_REXMTMIN;
+                       TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
+                           tp->t_rttmin, TCPTV_REXMTMAX, TCP_ADD_REXMTSLOP(tp));
+                       TCP_LOG_RTT_INFO(tp);
+               }

 
 

-               if (IN_FASTRECOVERY(tp)) {
+               if (tp->t_state == TCPS_SYN_SENT) {
+                       /*
+                        * The PTO for SYN_SENT reinitializes TCP as if it was a fresh
+                        * connection attempt
+                        */
+                       tp->snd_nxt = tp->snd_una;
+                       /*
+                        * Note:  We overload snd_recover to function also as the
+                        * snd_last variable described in RFC 2582
+                        */
+                       tp->snd_recover = tp->snd_max;

                        /*
                        /*

-                        * Send a probe to detect tail loss in a
-                        * recovery window when the connection is in
-                        * fast_recovery.
+                        * Force a segment to be sent.

                         */
                         */

-                       old_snd_nxt = tp->snd_nxt;
-                       rescue_rxt = TRUE;
-                       VERIFY(SEQ_GEQ(tp->snd_fack, tp->snd_una));
-                       snd_len = min((tp->snd_recover - tp->snd_fack),
-                           tp->t_maxseg);
-                       tp->snd_nxt = tp->snd_recover - snd_len;
-                       tcpstat.tcps_pto_in_recovery++;
-                       tcp_ccdbg_trace(tp, NULL, TCP_CC_TLP_IN_FASTRECOVERY);
+                       tp->t_flags |= TF_ACKNOW;
+
+                       /* If timing a segment in this window, stop the timer */
+                       tp->t_rtttime = 0;

                } else {
                } else {

+                       int32_t snd_len;
+

                        /*
                         * If there is no new data to send or if the
                         * connection is limited by receive window then
                        /*
                         * If there is no new data to send or if the
                         * connection is limited by receive window then


@@ -1193,23 +1662,78 @@ fc_output:
                        }
                }
 
                        }
                }
 

-               /* Note that tail loss probe is being sent */
-               tp->t_flagsext |= TF_SENT_TLPROBE;
-               tp->t_tlpstart = tcp_now;
+               tcpstat.tcps_pto++;
+               if (tp->t_flagsext & TF_IF_PROBING) {
+                       tcpstat.tcps_probe_if++;
+               }
+
+               /* If timing a segment in this window, stop the timer */
+               tp->t_rtttime = 0;
+               /* Note that tail loss probe is being sent. Exclude IF probe */
+               if (!(tp->t_flagsext & TF_IF_PROBING)) {
+                       tp->t_flagsext |= TF_SENT_TLPROBE;
+                       tp->t_tlpstart = tcp_now;
+               }

 
                tp->snd_cwnd += tp->t_maxseg;
 
                tp->snd_cwnd += tp->t_maxseg;

-               (void )tcp_output(tp);
-               tp->snd_cwnd -= tp->t_maxseg;
+               /*
+                * When tail-loss-probe fires, we reset the RTO timer, because
+                * a probe just got sent, so we are good to push out the timer.
+                *
+                * Set to 0 to ensure that tcp_output() will reschedule it
+                */
+               tp->t_timer[TCPT_REXMT] = 0;
+               ret = tcp_output(tp);
+
+#if (DEBUG || DEVELOPMENT)
+               if ((tp->t_flagsext & TF_IF_PROBING) &&
+                   ((IFNET_IS_COMPANION_LINK(tp->t_inpcb->inp_last_outifp)) ||
+                   tp->t_state == TCPS_SYN_SENT)) {
+                       if (ret == 0 && tcp_probe_if_fix_port > 0 &&
+                           tcp_probe_if_fix_port <= IPPORT_HILASTAUTO) {
+                               tp->t_timer[TCPT_REXMT] = 0;
+                               tcp_set_lotimer_index(tp);
+                       }

 
 

-               tp->t_tlphighrxt = tp->snd_nxt;
+                       os_log(OS_LOG_DEFAULT,
+                           "%s: sent %s probe for %u > %u on interface %s"
+                           " (%u) %s(%d)",
+                           __func__,
+                           tp->t_state == TCPS_SYN_SENT ? "SYN" : "data",
+                           ntohs(tp->t_inpcb->inp_lport),
+                           ntohs(tp->t_inpcb->inp_fport),
+                           if_name(tp->t_inpcb->inp_last_outifp),
+                           tp->t_inpcb->inp_last_outifp->if_index,
+                           ret == 0 ? "succeeded" :"failed", ret);
+               }
+#endif /* DEBUG || DEVELOPMENT */

 
                /*
 
                /*

-                * If a tail loss probe was sent after entering recovery,
-                * restore the old snd_nxt value so that other packets
-                * will get retransmitted correctly.
+                * When the connection is not idle, make sure the retransmission timer
+                * is armed because it was set to zero above

                 */
                 */

-               if (rescue_rxt)
-                       tp->snd_nxt = old_snd_nxt;
+               if ((tp->t_timer[TCPT_REXMT] == 0 || tp->t_timer[TCPT_PERSIST] == 0) &&
+                   (tp->t_inpcb->inp_socket->so_snd.sb_cc != 0 || tp->t_state == TCPS_SYN_SENT ||
+                   tp->t_state == TCPS_SYN_RECEIVED)) {
+                       tp->t_timer[TCPT_REXMT] =
+                           OFFSET_FROM_START(tp, tp->t_rxtcur);
+
+                       os_log(OS_LOG_DEFAULT,
+                           "%s: tcp_output() returned %u with retransmission timer disabled "
+                           "for %u > %u in state %d, reset timer to %d",
+                           __func__, ret,
+                           ntohs(tp->t_inpcb->inp_lport),
+                           ntohs(tp->t_inpcb->inp_fport),
+                           tp->t_state,
+                           tp->t_timer[TCPT_REXMT]);
+
+                       tcp_check_timer_state(tp);
+               }
+               tp->snd_cwnd -= tp->t_maxseg;
+
+               if (!(tp->t_flagsext & TF_IF_PROBING)) {
+                       tp->t_tlphighrxt = tp->snd_nxt;
+               }

                break;
        }
        case TCPT_DELAYFR:
                break;
        }
        case TCPT_DELAYFR:


@@ -1223,37 +1747,42 @@ fc_output:
                 */
                if (IN_FASTRECOVERY(tp) ||
                    SEQ_GEQ(tp->snd_una, tp->snd_recover) ||
                 */
                if (IN_FASTRECOVERY(tp) ||
                    SEQ_GEQ(tp->snd_una, tp->snd_recover) ||

-                   tp->t_rxtshift > 0)
+                   tp->t_rxtshift > 0) {

                        break;
                        break;

+               }

 
                VERIFY(SACK_ENABLED(tp));
 
                VERIFY(SACK_ENABLED(tp));

-               if (CC_ALGO(tp)->pre_fr != NULL)
+               tcp_rexmt_save_state(tp);
+               if (CC_ALGO(tp)->pre_fr != NULL) {

                        CC_ALGO(tp)->pre_fr(tp);
                        CC_ALGO(tp)->pre_fr(tp);

+                       if (TCP_ECN_ENABLED(tp)) {
+                               tp->ecn_flags |= TE_SENDCWR;
+                       }
+               }

                ENTER_FASTRECOVERY(tp);
                ENTER_FASTRECOVERY(tp);

-               if ((tp->ecn_flags & TE_ECN_ON) == TE_ECN_ON)
-                       tp->ecn_flags |= TE_SENDCWR;

 
                tp->t_timer[TCPT_REXMT] = 0;
                tcpstat.tcps_sack_recovery_episode++;
 
                tp->t_timer[TCPT_REXMT] = 0;
                tcpstat.tcps_sack_recovery_episode++;

+               tp->t_sack_recovery_episode++;

                tp->sack_newdata = tp->snd_nxt;
                tp->snd_cwnd = tp->t_maxseg;
                tcp_ccdbg_trace(tp, NULL, TCP_CC_ENTER_FASTRECOVERY);
                (void) tcp_output(tp);
                break;
                tp->sack_newdata = tp->snd_nxt;
                tp->snd_cwnd = tp->t_maxseg;
                tcp_ccdbg_trace(tp, NULL, TCP_CC_ENTER_FASTRECOVERY);
                (void) tcp_output(tp);
                break;

-       dropit:
+dropit:

                tcpstat.tcps_keepdrops++;
                tcpstat.tcps_keepdrops++;

-               postevent(so, 0, EV_TIMEOUT);

                soevent(so,
                soevent(so,

-                   (SO_FILT_HINT_LOCKED|SO_FILT_HINT_TIMEOUT));
+                   (SO_FILT_HINT_LOCKED | SO_FILT_HINT_TIMEOUT));

                tp = tcp_drop(tp, ETIMEDOUT);
                break;
        }
 #if TCPDEBUG
                tp = tcp_drop(tp, ETIMEDOUT);
                break;
        }
 #if TCPDEBUG

-       if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
+       if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) {

                tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
                tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,

-                         PRU_SLOWTIMO);
+                   PRU_SLOWTIMO);
+       }

 #endif
 #endif

-       return (tp);
+       return tp;

 }
 
 /* Remove a timer entry from timer list */
 }
 
 /* Remove a timer entry from timer list */


@@ -1262,20 +1791,21 @@ tcp_remove_timer(struct tcpcb *tp)
 {
        struct tcptimerlist *listp = &tcp_timer_list;
 
 {
        struct tcptimerlist *listp = &tcp_timer_list;
 

-       lck_mtx_assert(&tp->t_inpcb->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
+       socket_lock_assert_owned(tp->t_inpcb->inp_socket);

        if (!(TIMER_IS_ON_LIST(tp))) {
                return;
        }
        lck_mtx_lock(listp->mtx);
        if (!(TIMER_IS_ON_LIST(tp))) {
                return;
        }
        lck_mtx_lock(listp->mtx);

-       
+

        /* Check if pcb is on timer list again after acquiring the lock */
        if (!(TIMER_IS_ON_LIST(tp))) {
                lck_mtx_unlock(listp->mtx);
                return;
        }
        /* Check if pcb is on timer list again after acquiring the lock */
        if (!(TIMER_IS_ON_LIST(tp))) {
                lck_mtx_unlock(listp->mtx);
                return;
        }

-       
-       if (listp->next_te != NULL && listp->next_te == &tp->tentry)
+
+       if (listp->next_te != NULL && listp->next_te == &tp->tentry) {

                listp->next_te = LIST_NEXT(&tp->tentry, le);
                listp->next_te = LIST_NEXT(&tp->tentry, le);

+       }

 
        LIST_REMOVE(&tp->tentry, le);
        tp->t_flags &= ~(TF_TIMER_ONLIST);
 
        LIST_REMOVE(&tp->tentry, le);
        tp->t_flags &= ~(TF_TIMER_ONLIST);


@@ -1304,42 +1834,47 @@ need_to_resched_timerlist(u_int32_t runtime, u_int16_t mode)
         * in flux. In this case always acquire the lock and set the state
         * correctly.
         */
         * in flux. In this case always acquire the lock and set the state
         * correctly.
         */

-       if (listp->running)
-               return (TRUE);
+       if (listp->running) {
+               return TRUE;
+       }

 
 

-       if (!listp->scheduled)
-               return (TRUE);
+       if (!listp->scheduled) {
+               return TRUE;
+       }

 
        diff = timer_diff(listp->runtime, 0, runtime, 0);
        if (diff <= 0) {
                /* The list is going to run before this timer */
 
        diff = timer_diff(listp->runtime, 0, runtime, 0);
        if (diff <= 0) {
                /* The list is going to run before this timer */

-               return (FALSE);
+               return FALSE;

        } else {
                if (mode & TCP_TIMERLIST_10MS_MODE) {
        } else {
                if (mode & TCP_TIMERLIST_10MS_MODE) {

-                       if (diff <= TCP_TIMER_10MS_QUANTUM)
-                               return (FALSE);
+                       if (diff <= TCP_TIMER_10MS_QUANTUM) {
+                               return FALSE;
+                       }

                } else if (mode & TCP_TIMERLIST_100MS_MODE) {
                } else if (mode & TCP_TIMERLIST_100MS_MODE) {

-                       if (diff <= TCP_TIMER_100MS_QUANTUM)
-                               return (FALSE);
+                       if (diff <= TCP_TIMER_100MS_QUANTUM) {
+                               return FALSE;
+                       }

                } else {
                } else {

-                       if (diff <= TCP_TIMER_500MS_QUANTUM)
-                               return (FALSE);
+                       if (diff <= TCP_TIMER_500MS_QUANTUM) {
+                               return FALSE;
+                       }

                }
        }
                }
        }

-       return (TRUE);
+       return TRUE;

 }
 
 void
 }
 
 void

-tcp_sched_timerlist(uint32_t offset) 
+tcp_sched_timerlist(uint32_t offset)

 {
 {

-

        uint64_t deadline = 0;
        struct tcptimerlist *listp = &tcp_timer_list;
 
        uint64_t deadline = 0;
        struct tcptimerlist *listp = &tcp_timer_list;
 

-       lck_mtx_assert(listp->mtx, LCK_MTX_ASSERT_OWNED);
+       LCK_MTX_ASSERT(listp->mtx, LCK_MTX_ASSERT_OWNED);

 
        offset = min(offset, TCP_TIMERLIST_MAX_OFFSET);
        listp->runtime = tcp_now + offset;
 
        offset = min(offset, TCP_TIMERLIST_MAX_OFFSET);
        listp->runtime = tcp_now + offset;

+       listp->schedtime = tcp_now;

        if (listp->runtime == 0) {
                listp->runtime++;
                offset++;
        if (listp->runtime == 0) {
                listp->runtime++;
                offset++;


@@ -1354,15 +1889,16 @@ tcp_sched_timerlist(uint32_t offset)
 /*
  * Function to run the timers for a connection.
  *
 /*
  * Function to run the timers for a connection.
  *

- * Returns the offset of next timer to be run for this connection which 
+ * Returns the offset of next timer to be run for this connection which

  * can be used to reschedule the timerlist.
  *
  * te_mode is an out parameter that indicates the modes of active
  * timers for this connection.
  */
 u_int32_t
  * can be used to reschedule the timerlist.
  *
  * te_mode is an out parameter that indicates the modes of active
  * timers for this connection.
  */
 u_int32_t

-tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode) {
-
+tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode,
+    u_int16_t probe_if_index)
+{

        struct socket *so;
        u_int16_t i = 0, index = TCPT_NONE, lo_index = TCPT_NONE;
        u_int32_t timer_val, offset = 0, lo_timer = 0;
        struct socket *so;
        u_int16_t i = 0, index = TCPT_NONE, lo_index = TCPT_NONE;
        u_int32_t timer_val, offset = 0, lo_timer = 0;


@@ -1374,30 +1910,42 @@ tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode) {
        bzero(needtorun, sizeof(needtorun));
        *te_mode = 0;
 
        bzero(needtorun, sizeof(needtorun));
        *te_mode = 0;
 

-       tcp_lock(tp->t_inpcb->inp_socket, 1, 0);
+       socket_lock(tp->t_inpcb->inp_socket, 1);

 
        so = tp->t_inpcb->inp_socket;
 
        so = tp->t_inpcb->inp_socket;

-       /* Release the want count on inp */ 
+       /* Release the want count on inp */

        if (in_pcb_checkstate(tp->t_inpcb, WNT_RELEASE, 1)
        if (in_pcb_checkstate(tp->t_inpcb, WNT_RELEASE, 1)

-               == WNT_STOPUSING) {
+           == WNT_STOPUSING) {

                if (TIMER_IS_ON_LIST(tp)) {
                        tcp_remove_timer(tp);
                }
 
                if (TIMER_IS_ON_LIST(tp)) {
                        tcp_remove_timer(tp);
                }
 

-               /* Looks like the TCP connection got closed while we 
+               /* Looks like the TCP connection got closed while we

                 * were waiting for the lock.. Done
                 */
                goto done;
        }
 
                 * were waiting for the lock.. Done
                 */
                goto done;
        }
 

+       /*
+        * If this connection is over an interface that needs to
+        * be probed, send probe packets to reinitiate communication.
+        */
+       if (TCP_IF_STATE_CHANGED(tp, probe_if_index)) {
+               tp->t_flagsext |= TF_IF_PROBING;
+               tcp_timers(tp, TCPT_PTO);
+               tp->t_timer[TCPT_PTO] = 0;
+               tp->t_flagsext &= ~TF_IF_PROBING;
+       }
+

        /*
         * Since the timer thread needs to wait for tcp lock, it may race
         * with another thread that can cancel or reschedule the timer
         * that is about to run. Check if we need to run anything.
         */
        /*
         * Since the timer thread needs to wait for tcp lock, it may race
         * with another thread that can cancel or reschedule the timer
         * that is about to run. Check if we need to run anything.
         */

-       if ((index = tp->tentry.index) == TCPT_NONE)
+       if ((index = tp->tentry.index) == TCPT_NONE) {

                goto done;
                goto done;

-       
+       }
+

        timer_val = tp->t_timer[index];
 
        diff = timer_diff(tp->tentry.runtime, 0, tcp_now, 0);
        timer_val = tp->t_timer[index];
 
        diff = timer_diff(tp->tentry.runtime, 0, tcp_now, 0);


@@ -1412,10 +1960,11 @@ tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode) {
        tp->t_timer[index] = 0;
        if (timer_val > 0) {
                tp = tcp_timers(tp, index);
        tp->t_timer[index] = 0;
        if (timer_val > 0) {
                tp = tcp_timers(tp, index);

-               if (tp == NULL)
+               if (tp == NULL) {

                        goto done;
                        goto done;

+               }

        }
        }

-       
+

        /*
         * Check if there are any other timers that need to be run.
         * While doing it, adjust the timer values wrt tcp_now.
        /*
         * Check if there are any other timers that need to be run.
         * While doing it, adjust the timer values wrt tcp_now.


@@ -1424,7 +1973,7 @@ tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode) {
        for (i = 0; i < TCPT_NTIMERS; ++i) {
                if (tp->t_timer[i] != 0) {
                        diff = timer_diff(tp->tentry.timer_start,
        for (i = 0; i < TCPT_NTIMERS; ++i) {
                if (tp->t_timer[i] != 0) {
                        diff = timer_diff(tp->tentry.timer_start,

-                               tp->t_timer[i], tcp_now, 0);
+                           tp->t_timer[i], tcp_now, 0);

                        if (diff <= 0) {
                                needtorun[i] = TRUE;
                                count++;
                        if (diff <= 0) {
                                needtorun[i] = TRUE;
                                count++;


@@ -1439,16 +1988,17 @@ tcp_run_conn_timer(struct tcpcb *tp, u_int16_t *te_mode) {
                        }
                }
        }
                        }
                }
        }

-       
+

        tp->tentry.timer_start = tcp_now;
        tp->tentry.index = lo_index;
        VERIFY(tp->tentry.index == TCPT_NONE || tp->tentry.mode > 0);
 
        if (tp->tentry.index != TCPT_NONE) {
                tp->tentry.runtime = tp->tentry.timer_start +
        tp->tentry.timer_start = tcp_now;
        tp->tentry.index = lo_index;
        VERIFY(tp->tentry.index == TCPT_NONE || tp->tentry.mode > 0);
 
        if (tp->tentry.index != TCPT_NONE) {
                tp->tentry.runtime = tp->tentry.timer_start +

-                       tp->t_timer[tp->tentry.index];
-               if (tp->tentry.runtime == 0)
+                   tp->t_timer[tp->tentry.index];
+               if (tp->tentry.runtime == 0) {

                        tp->tentry.runtime++;
                        tp->tentry.runtime++;

+               }

        }
 
        if (count > 0) {
        }
 
        if (count > 0) {


@@ -1478,18 +2028,19 @@ done:
                offset = 0;
        }
 
                offset = 0;
        }
 

-       tcp_unlock(so, 1, 0);
-       return(offset);
+       socket_unlock(so, 1);
+       return offset;

 }
 
 void
 }
 
 void

-tcp_run_timerlist(void * arg1, void * arg2) {
+tcp_run_timerlist(void * arg1, void * arg2)
+{

 #pragma unused(arg1, arg2)
        struct tcptimerentry *te, *next_te;
        struct tcptimerlist *listp = &tcp_timer_list;
        struct tcpcb *tp;
        uint32_t next_timer = 0; /* offset of the next timer on the list */
 #pragma unused(arg1, arg2)
        struct tcptimerentry *te, *next_te;
        struct tcptimerlist *listp = &tcp_timer_list;
        struct tcpcb *tp;
        uint32_t next_timer = 0; /* offset of the next timer on the list */

-       u_int16_t te_mode = 0;  /* modes of all active timers in a tcpcb */
+       u_int16_t te_mode = 0;  /* modes of all active timers in a tcpcb */

        u_int16_t list_mode = 0; /* cumulative of modes of all tcpcbs */
        uint32_t active_count = 0;
 
        u_int16_t list_mode = 0; /* cumulative of modes of all tcpcbs */
        uint32_t active_count = 0;
 


@@ -1497,12 +2048,40 @@ tcp_run_timerlist(void * arg1, void * arg2) {
 
        lck_mtx_lock(listp->mtx);
 
 
        lck_mtx_lock(listp->mtx);
 

+       int32_t drift = tcp_now - listp->runtime;
+       if (drift <= 1) {
+               tcpstat.tcps_timer_drift_le_1_ms++;
+       } else if (drift <= 10) {
+               tcpstat.tcps_timer_drift_le_10_ms++;
+       } else if (drift <= 20) {
+               tcpstat.tcps_timer_drift_le_20_ms++;
+       } else if (drift <= 50) {
+               tcpstat.tcps_timer_drift_le_50_ms++;
+       } else if (drift <= 100) {
+               tcpstat.tcps_timer_drift_le_100_ms++;
+       } else if (drift <= 200) {
+               tcpstat.tcps_timer_drift_le_200_ms++;
+       } else if (drift <= 500) {
+               tcpstat.tcps_timer_drift_le_500_ms++;
+       } else if (drift <= 1000) {
+               tcpstat.tcps_timer_drift_le_1000_ms++;
+       } else {
+               tcpstat.tcps_timer_drift_gt_1000_ms++;
+       }
+

        listp->running = TRUE;
        listp->running = TRUE;

-       
+

        LIST_FOREACH_SAFE(te, &listp->lhead, le, next_te) {
                uint32_t offset = 0;
                uint32_t runtime = te->runtime;
        LIST_FOREACH_SAFE(te, &listp->lhead, le, next_te) {
                uint32_t offset = 0;
                uint32_t runtime = te->runtime;

-               if (te->index < TCPT_NONE && TSTMP_GT(runtime, tcp_now)) {
+
+               tp = TIMERENTRY_TO_TP(te);
+
+               /*
+                * An interface probe may need to happen before the previously scheduled runtime
+                */
+               if (te->index < TCPT_NONE && TSTMP_GT(runtime, tcp_now) &&
+                   !TCP_IF_STATE_CHANGED(tp, listp->probe_if_index)) {

                        offset = timer_diff(runtime, 0, tcp_now, 0);
                        if (next_timer == 0 || offset < next_timer) {
                                next_timer = offset;
                        offset = timer_diff(runtime, 0, tcp_now, 0);
                        if (next_timer == 0 || offset < next_timer) {
                                next_timer = offset;


@@ -1511,8 +2090,6 @@ tcp_run_timerlist(void * arg1, void * arg2) {
                        continue;
                }
 
                        continue;
                }
 

-               tp = TIMERENTRY_TO_TP(te);
-

                /*
                 * Acquire an inp wantcnt on the inpcb so that the socket
                 * won't get detached even if tcp_close is called
                /*
                 * Acquire an inp wantcnt on the inpcb so that the socket
                 * won't get detached even if tcp_close is called


@@ -1523,7 +2100,7 @@ tcp_run_timerlist(void * arg1, void * arg2) {
                         * Some how this pcb went into dead state while
                         * on the timer list, just take it off the list.
                         * Since the timer list entry pointers are
                         * Some how this pcb went into dead state while
                         * on the timer list, just take it off the list.
                         * Since the timer list entry pointers are

-                        * protected by the timer list lock, we can 
+                        * protected by the timer list lock, we can

                         * do it here without the socket lock.
                         */
                        if (TIMER_IS_ON_LIST(tp)) {
                         * do it here without the socket lock.
                         */
                        if (TIMER_IS_ON_LIST(tp)) {


@@ -1544,15 +2121,16 @@ tcp_run_timerlist(void * arg1, void * arg2) {
                 * release the lock, this pointer will be updated to the
                 * element after that.
                 */
                 * release the lock, this pointer will be updated to the
                 * element after that.
                 */

-               listp->next_te = next_te; 
+               listp->next_te = next_te;

 
                VERIFY_NEXT_LINK(&tp->tentry, le);
                VERIFY_PREV_LINK(&tp->tentry, le);
 
                lck_mtx_unlock(listp->mtx);
 
 
                VERIFY_NEXT_LINK(&tp->tentry, le);
                VERIFY_PREV_LINK(&tp->tentry, le);
 
                lck_mtx_unlock(listp->mtx);
 

-               offset = tcp_run_conn_timer(tp, &te_mode);
-               
+               offset = tcp_run_conn_timer(tp, &te_mode,
+                   listp->probe_if_index);
+

                lck_mtx_lock(listp->mtx);
 
                next_te = listp->next_te;
                lck_mtx_lock(listp->mtx);
 
                next_te = listp->next_te;


@@ -1561,21 +2139,23 @@ tcp_run_timerlist(void * arg1, void * arg2) {
                if (offset > 0 && te_mode != 0) {
                        list_mode |= te_mode;
 
                if (offset > 0 && te_mode != 0) {
                        list_mode |= te_mode;
 

-                       if (next_timer == 0 || offset < next_timer)
+                       if (next_timer == 0 || offset < next_timer) {

                                next_timer = offset;
                                next_timer = offset;

+                       }

                }
        }
 
        if (!LIST_EMPTY(&listp->lhead)) {
                }
        }
 
        if (!LIST_EMPTY(&listp->lhead)) {

-               u_int16_t next_mode = 0;
+               uint32_t next_mode = 0;

                if ((list_mode & TCP_TIMERLIST_10MS_MODE) ||
                if ((list_mode & TCP_TIMERLIST_10MS_MODE) ||

-                       (listp->pref_mode & TCP_TIMERLIST_10MS_MODE))
+                   (listp->pref_mode & TCP_TIMERLIST_10MS_MODE)) {

                        next_mode = TCP_TIMERLIST_10MS_MODE;
                        next_mode = TCP_TIMERLIST_10MS_MODE;

-               else if ((list_mode & TCP_TIMERLIST_100MS_MODE) ||
-                       (listp->pref_mode & TCP_TIMERLIST_100MS_MODE))
+               } else if ((list_mode & TCP_TIMERLIST_100MS_MODE) ||
+                   (listp->pref_mode & TCP_TIMERLIST_100MS_MODE)) {

                        next_mode = TCP_TIMERLIST_100MS_MODE;
                        next_mode = TCP_TIMERLIST_100MS_MODE;

-               else
+               } else {

                        next_mode = TCP_TIMERLIST_500MS_MODE;
                        next_mode = TCP_TIMERLIST_500MS_MODE;

+               }

 
                if (next_mode != TCP_TIMERLIST_500MS_MODE) {
                        listp->idleruns = 0;
 
                if (next_mode != TCP_TIMERLIST_500MS_MODE) {
                        listp->idleruns = 0;


@@ -1598,12 +2178,14 @@ tcp_run_timerlist(void * arg1, void * arg2) {
                        }
                }
                listp->mode = next_mode;
                        }
                }
                listp->mode = next_mode;

-               if (listp->pref_offset != 0)
+               if (listp->pref_offset != 0) {

                        next_timer = min(listp->pref_offset, next_timer);
                        next_timer = min(listp->pref_offset, next_timer);

+               }

 
 

-               if (listp->mode == TCP_TIMERLIST_500MS_MODE)
+               if (listp->mode == TCP_TIMERLIST_500MS_MODE) {

                        next_timer = max(next_timer,
                        next_timer = max(next_timer,

-                               TCP_TIMER_500MS_QUANTUM);
+                           TCP_TIMER_500MS_QUANTUM);
+               }

 
                tcp_sched_timerlist(next_timer);
        } else {
 
                tcp_sched_timerlist(next_timer);
        } else {


@@ -1617,16 +2199,17 @@ tcp_run_timerlist(void * arg1, void * arg2) {
        listp->running = FALSE;
        listp->pref_mode = 0;
        listp->pref_offset = 0;
        listp->running = FALSE;
        listp->pref_mode = 0;
        listp->pref_offset = 0;

+       listp->probe_if_index = 0;

 
        lck_mtx_unlock(listp->mtx);
 }
 
 /*
 
        lck_mtx_unlock(listp->mtx);
 }
 
 /*

- * Function to check if the timerlist needs to be reschduled to run this
+ * Function to check if the timerlist needs to be rescheduled to run this

  * connection's timers correctly.
  */
  * connection's timers correctly.
  */

-void 
-tcp_sched_timers(struct tcpcb *tp) 
+void
+tcp_sched_timers(struct tcpcb *tp)

 {
        struct tcptimerentry *te = &tp->tentry;
        u_int16_t index = te->index;
 {
        struct tcptimerentry *te = &tp->tentry;
        u_int16_t index = te->index;


@@ -1665,26 +2248,29 @@ tcp_sched_timers(struct tcpcb *tp)
                        list_locked = TRUE;
                }
 
                        list_locked = TRUE;
                }
 

-               LIST_INSERT_HEAD(&listp->lhead, te, le);
-               tp->t_flags |= TF_TIMER_ONLIST;
+               if (!TIMER_IS_ON_LIST(tp)) {
+                       LIST_INSERT_HEAD(&listp->lhead, te, le);
+                       tp->t_flags |= TF_TIMER_ONLIST;

 
 

-               listp->entries++;
-               if (listp->entries > listp->maxentries)
-                       listp->maxentries = listp->entries;
+                       listp->entries++;
+                       if (listp->entries > listp->maxentries) {
+                               listp->maxentries = listp->entries;
+                       }

 
 

-               /* if the list is not scheduled, just schedule it */
-               if (!listp->scheduled)
-                       goto schedule;
+                       /* if the list is not scheduled, just schedule it */
+                       if (!listp->scheduled) {
+                               goto schedule;
+                       }
+               }

        }
 
        }
 

-

        /*
         * Timer entry is currently on the list, check if the list needs
         * to be rescheduled.
         */
        if (need_to_resched_timerlist(te->runtime, mode)) {
                tcp_resched_timerlist++;
        /*
         * Timer entry is currently on the list, check if the list needs
         * to be rescheduled.
         */
        if (need_to_resched_timerlist(te->runtime, mode)) {
                tcp_resched_timerlist++;

-       
+

                if (!list_locked) {
                        lck_mtx_lock(listp->mtx);
                        list_locked = TRUE;
                if (!list_locked) {
                        lck_mtx_lock(listp->mtx);
                        list_locked = TRUE;


@@ -1696,7 +2282,7 @@ tcp_sched_timers(struct tcpcb *tp)
                if (listp->running) {
                        listp->pref_mode |= mode;
                        if (listp->pref_offset == 0 ||
                if (listp->running) {
                        listp->pref_mode |= mode;
                        if (listp->pref_offset == 0 ||

-                               offset < listp->pref_offset) {
+                           offset < listp->pref_offset) {

                                listp->pref_offset = offset;
                        }
                } else {
                                listp->pref_offset = offset;
                        }
                } else {


@@ -1708,10 +2294,11 @@ tcp_sched_timers(struct tcpcb *tp)
                                int32_t diff;
                                diff = timer_diff(listp->runtime, 0,
                                    tcp_now, offset);
                                int32_t diff;
                                diff = timer_diff(listp->runtime, 0,
                                    tcp_now, offset);

-                               if (diff <= 0)
+                               if (diff <= 0) {

                                        goto done;
                                        goto done;

-                               else
+                               } else {

                                        goto schedule;
                                        goto schedule;

+                               }

                        } else {
                                goto schedule;
                        }
                        } else {
                                goto schedule;
                        }


@@ -1730,22 +2317,25 @@ schedule:
                listp->idleruns = 0;
                offset = min(offset, TCP_TIMER_10MS_QUANTUM);
        } else if (mode & TCP_TIMERLIST_100MS_MODE) {
                listp->idleruns = 0;
                offset = min(offset, TCP_TIMER_10MS_QUANTUM);
        } else if (mode & TCP_TIMERLIST_100MS_MODE) {

-               if (listp->mode > TCP_TIMERLIST_100MS_MODE)
+               if (listp->mode > TCP_TIMERLIST_100MS_MODE) {

                        listp->mode = TCP_TIMERLIST_100MS_MODE;
                        listp->mode = TCP_TIMERLIST_100MS_MODE;

+               }

                listp->idleruns = 0;
                offset = min(offset, TCP_TIMER_100MS_QUANTUM);
        }
        tcp_sched_timerlist(offset);
 
 done:
                listp->idleruns = 0;
                offset = min(offset, TCP_TIMER_100MS_QUANTUM);
        }
        tcp_sched_timerlist(offset);
 
 done:

-       if (list_locked)
+       if (list_locked) {

                lck_mtx_unlock(listp->mtx);
                lck_mtx_unlock(listp->mtx);

+       }

 
        return;
 }
 
        return;
 }

-               
+

 static inline void
 static inline void

-tcp_set_lotimer_index(struct tcpcb *tp) {
+tcp_set_lotimer_index(struct tcpcb *tp)
+{

        uint16_t i, lo_index = TCPT_NONE, mode = 0;
        uint32_t lo_timer = 0;
        for (i = 0; i < TCPT_NTIMERS; ++i) {
        uint16_t i, lo_index = TCPT_NONE, mode = 0;
        uint32_t lo_timer = 0;
        for (i = 0; i < TCPT_NTIMERS; ++i) {


@@ -1762,20 +2352,22 @@ tcp_set_lotimer_index(struct tcpcb *tp) {
        VERIFY(tp->tentry.index == TCPT_NONE || tp->tentry.mode > 0);
 
        if (tp->tentry.index != TCPT_NONE) {
        VERIFY(tp->tentry.index == TCPT_NONE || tp->tentry.mode > 0);
 
        if (tp->tentry.index != TCPT_NONE) {

-               tp->tentry.runtime = tp->tentry.timer_start 
+               tp->tentry.runtime = tp->tentry.timer_start

                    + tp->t_timer[tp->tentry.index];
                    + tp->t_timer[tp->tentry.index];

-               if (tp->tentry.runtime == 0)
+               if (tp->tentry.runtime == 0) {

                        tp->tentry.runtime++;
                        tp->tentry.runtime++;

+               }

        }
 }
 
 void
        }
 }
 
 void

-tcp_check_timer_state(struct tcpcb *tp) {
-
-       lck_mtx_assert(&tp->t_inpcb->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
+tcp_check_timer_state(struct tcpcb *tp)
+{
+       socket_lock_assert_owned(tp->t_inpcb->inp_socket);

 
 

-       if (tp->t_inpcb->inp_flags2 & INP2_TIMEWAIT)
+       if (tp->t_inpcb->inp_flags2 & INP2_TIMEWAIT) {

                return;
                return;

+       }

 
        tcp_set_lotimer_index(tp);
 
 
        tcp_set_lotimer_index(tp);
 


@@ -1783,6 +2375,34 @@ tcp_check_timer_state(struct tcpcb *tp) {
        return;
 }
 
        return;
 }
 

+static inline void
+tcp_cumulative_stat(u_int32_t cur, u_int32_t *prev, u_int32_t *dest)
+{
+       /* handle wrap around */
+       int32_t diff = (int32_t) (cur - *prev);
+       if (diff > 0) {
+               *dest = diff;
+       } else {
+               *dest = 0;
+       }
+       *prev = cur;
+       return;
+}
+
+static inline void
+tcp_cumulative_stat64(u_int64_t cur, u_int64_t *prev, u_int64_t *dest)
+{
+       /* handle wrap around */
+       int64_t diff = (int64_t) (cur - *prev);
+       if (diff > 0) {
+               *dest = diff;
+       } else {
+               *dest = 0;
+       }
+       *prev = cur;
+       return;
+}
+

 __private_extern__ void
 tcp_report_stats(void)
 {
 __private_extern__ void
 tcp_report_stats(void)
 {


@@ -1790,12 +2410,14 @@ tcp_report_stats(void)
        struct sockaddr_in dst;
        struct sockaddr_in6 dst6;
        struct rtentry *rt = NULL;
        struct sockaddr_in dst;
        struct sockaddr_in6 dst6;
        struct rtentry *rt = NULL;

-       u_int64_t var, uptime;  
+       static struct tcp_last_report_stats prev;
+       u_int64_t var, uptime;

 
 

-#define        stat    data.u.tcp_stats
+#define stat    data.u.tcp_stats

        if (((uptime = net_uptime()) - tcp_last_report_time) <
        if (((uptime = net_uptime()) - tcp_last_report_time) <

-               TCP_REPORT_STATS_INTERVAL)
+           tcp_report_stats_interval) {

                return;
                return;

+       }

 
        tcp_last_report_time = uptime;
 
 
        tcp_last_report_time = uptime;
 


@@ -1809,12 +2431,12 @@ tcp_report_stats(void)
        /* ipv4 avg rtt */
        lck_mtx_lock(rnh_lock);
        rt =  rt_lookup(TRUE, (struct sockaddr *)&dst, NULL,
        /* ipv4 avg rtt */
        lck_mtx_lock(rnh_lock);
        rt =  rt_lookup(TRUE, (struct sockaddr *)&dst, NULL,

-               rt_tables[AF_INET], IFSCOPE_NONE);
+           rt_tables[AF_INET], IFSCOPE_NONE);

        lck_mtx_unlock(rnh_lock);
        if (rt != NULL) {
                RT_LOCK(rt);
                if (rt_primary_default(rt, rt_key(rt)) &&
        lck_mtx_unlock(rnh_lock);
        if (rt != NULL) {
                RT_LOCK(rt);
                if (rt_primary_default(rt, rt_key(rt)) &&

-                       rt->rt_stats != NULL) {
+                   rt->rt_stats != NULL) {

                        stat.ipv4_avgrtt = rt->rt_stats->nstat_avg_rtt;
                }
                RT_UNLOCK(rt);
                        stat.ipv4_avgrtt = rt->rt_stats->nstat_avg_rtt;
                }
                RT_UNLOCK(rt);


@@ -1828,13 +2450,13 @@ tcp_report_stats(void)
        dst6.sin6_family = AF_INET6;
 
        lck_mtx_lock(rnh_lock);
        dst6.sin6_family = AF_INET6;
 
        lck_mtx_lock(rnh_lock);

-       rt = rt_lookup(TRUE,(struct sockaddr *)&dst6, NULL,
-               rt_tables[AF_INET6], IFSCOPE_NONE);
+       rt = rt_lookup(TRUE, (struct sockaddr *)&dst6, NULL,
+           rt_tables[AF_INET6], IFSCOPE_NONE);

        lck_mtx_unlock(rnh_lock);
        if (rt != NULL) {
                RT_LOCK(rt);
                if (rt_primary_default(rt, rt_key(rt)) &&
        lck_mtx_unlock(rnh_lock);
        if (rt != NULL) {
                RT_LOCK(rt);
                if (rt_primary_default(rt, rt_key(rt)) &&

-                       rt->rt_stats != NULL) {
+                   rt->rt_stats != NULL) {

                        stat.ipv6_avgrtt = rt->rt_stats->nstat_avg_rtt;
                }
                RT_UNLOCK(rt);
                        stat.ipv6_avgrtt = rt->rt_stats->nstat_avg_rtt;
                }
                RT_UNLOCK(rt);


@@ -1845,31 +2467,486 @@ tcp_report_stats(void)
        /* send packet loss rate, shift by 10 for precision */
        if (tcpstat.tcps_sndpack > 0 && tcpstat.tcps_sndrexmitpack > 0) {
                var = tcpstat.tcps_sndrexmitpack << 10;
        /* send packet loss rate, shift by 10 for precision */
        if (tcpstat.tcps_sndpack > 0 && tcpstat.tcps_sndrexmitpack > 0) {
                var = tcpstat.tcps_sndrexmitpack << 10;

-               stat.send_plr = (var * 100) / tcpstat.tcps_sndpack;
+               stat.send_plr = (uint32_t)((var * 100) / tcpstat.tcps_sndpack);

        }
 
        /* recv packet loss rate, shift by 10 for precision */
        if (tcpstat.tcps_rcvpack > 0 && tcpstat.tcps_recovered_pkts > 0) {
                var = tcpstat.tcps_recovered_pkts << 10;
        }
 
        /* recv packet loss rate, shift by 10 for precision */
        if (tcpstat.tcps_rcvpack > 0 && tcpstat.tcps_recovered_pkts > 0) {
                var = tcpstat.tcps_recovered_pkts << 10;

-               stat.recv_plr = (var * 100) / tcpstat.tcps_rcvpack;
+               stat.recv_plr = (uint32_t)((var * 100) / tcpstat.tcps_rcvpack);

        }
 
        /* RTO after tail loss, shift by 10 for precision */
        }
 
        /* RTO after tail loss, shift by 10 for precision */

-       if (tcpstat.tcps_sndrexmitpack > 0 
+       if (tcpstat.tcps_sndrexmitpack > 0

            && tcpstat.tcps_tailloss_rto > 0) {
                var = tcpstat.tcps_tailloss_rto << 10;
                stat.send_tlrto_rate =
            && tcpstat.tcps_tailloss_rto > 0) {
                var = tcpstat.tcps_tailloss_rto << 10;
                stat.send_tlrto_rate =

-                       (var * 100) / tcpstat.tcps_sndrexmitpack;
+                   (uint32_t)((var * 100) / tcpstat.tcps_sndrexmitpack);

        }
        }

-       
+

        /* packet reordering */
        if (tcpstat.tcps_sndpack > 0 && tcpstat.tcps_reordered_pkts > 0) {
                var = tcpstat.tcps_reordered_pkts << 10;
                stat.send_reorder_rate =
        /* packet reordering */
        if (tcpstat.tcps_sndpack > 0 && tcpstat.tcps_reordered_pkts > 0) {
                var = tcpstat.tcps_reordered_pkts << 10;
                stat.send_reorder_rate =

-                       (var * 100) / tcpstat.tcps_sndpack;
+                   (uint32_t)((var * 100) / tcpstat.tcps_sndpack);
+       }
+
+       if (tcp_ecn_outbound == 1) {
+               stat.ecn_client_enabled = 1;

        }
        }

+       if (tcp_ecn_inbound == 1) {
+               stat.ecn_server_enabled = 1;
+       }
+       tcp_cumulative_stat(tcpstat.tcps_connattempt,
+           &prev.tcps_connattempt, &stat.connection_attempts);
+       tcp_cumulative_stat(tcpstat.tcps_accepts,
+           &prev.tcps_accepts, &stat.connection_accepts);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_client_setup,
+           &prev.tcps_ecn_client_setup, &stat.ecn_client_setup);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_server_setup,
+           &prev.tcps_ecn_server_setup, &stat.ecn_server_setup);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_client_success,
+           &prev.tcps_ecn_client_success, &stat.ecn_client_success);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_server_success,
+           &prev.tcps_ecn_server_success, &stat.ecn_server_success);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_not_supported,
+           &prev.tcps_ecn_not_supported, &stat.ecn_not_supported);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_lost_syn,
+           &prev.tcps_ecn_lost_syn, &stat.ecn_lost_syn);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_lost_synack,
+           &prev.tcps_ecn_lost_synack, &stat.ecn_lost_synack);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_recv_ce,
+           &prev.tcps_ecn_recv_ce, &stat.ecn_recv_ce);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_recv_ece,
+           &prev.tcps_ecn_recv_ece, &stat.ecn_recv_ece);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_recv_ece,
+           &prev.tcps_ecn_recv_ece, &stat.ecn_recv_ece);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_sent_ece,
+           &prev.tcps_ecn_sent_ece, &stat.ecn_sent_ece);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_sent_ece,
+           &prev.tcps_ecn_sent_ece, &stat.ecn_sent_ece);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_conn_recv_ce,
+           &prev.tcps_ecn_conn_recv_ce, &stat.ecn_conn_recv_ce);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_conn_recv_ece,
+           &prev.tcps_ecn_conn_recv_ece, &stat.ecn_conn_recv_ece);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_conn_plnoce,
+           &prev.tcps_ecn_conn_plnoce, &stat.ecn_conn_plnoce);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_conn_pl_ce,
+           &prev.tcps_ecn_conn_pl_ce, &stat.ecn_conn_pl_ce);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_conn_nopl_ce,
+           &prev.tcps_ecn_conn_nopl_ce, &stat.ecn_conn_nopl_ce);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_fallback_synloss,
+           &prev.tcps_ecn_fallback_synloss, &stat.ecn_fallback_synloss);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_fallback_reorder,
+           &prev.tcps_ecn_fallback_reorder, &stat.ecn_fallback_reorder);
+       tcp_cumulative_stat(tcpstat.tcps_ecn_fallback_ce,
+           &prev.tcps_ecn_fallback_ce, &stat.ecn_fallback_ce);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_syn_data_rcv,
+           &prev.tcps_tfo_syn_data_rcv, &stat.tfo_syn_data_rcv);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_req_rcv,
+           &prev.tcps_tfo_cookie_req_rcv, &stat.tfo_cookie_req_rcv);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_sent,
+           &prev.tcps_tfo_cookie_sent, &stat.tfo_cookie_sent);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_invalid,
+           &prev.tcps_tfo_cookie_invalid, &stat.tfo_cookie_invalid);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_req,
+           &prev.tcps_tfo_cookie_req, &stat.tfo_cookie_req);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_rcv,
+           &prev.tcps_tfo_cookie_rcv, &stat.tfo_cookie_rcv);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_syn_data_sent,
+           &prev.tcps_tfo_syn_data_sent, &stat.tfo_syn_data_sent);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_syn_data_acked,
+           &prev.tcps_tfo_syn_data_acked, &stat.tfo_syn_data_acked);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_syn_loss,
+           &prev.tcps_tfo_syn_loss, &stat.tfo_syn_loss);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_blackhole,
+           &prev.tcps_tfo_blackhole, &stat.tfo_blackhole);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_cookie_wrong,
+           &prev.tcps_tfo_cookie_wrong, &stat.tfo_cookie_wrong);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_no_cookie_rcv,
+           &prev.tcps_tfo_no_cookie_rcv, &stat.tfo_no_cookie_rcv);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_heuristics_disable,
+           &prev.tcps_tfo_heuristics_disable, &stat.tfo_heuristics_disable);
+       tcp_cumulative_stat(tcpstat.tcps_tfo_sndblackhole,
+           &prev.tcps_tfo_sndblackhole, &stat.tfo_sndblackhole);
+
+
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_handover_attempt,
+           &prev.tcps_mptcp_handover_attempt, &stat.mptcp_handover_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_interactive_attempt,
+           &prev.tcps_mptcp_interactive_attempt, &stat.mptcp_interactive_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_aggregate_attempt,
+           &prev.tcps_mptcp_aggregate_attempt, &stat.mptcp_aggregate_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_handover_attempt,
+           &prev.tcps_mptcp_fp_handover_attempt, &stat.mptcp_fp_handover_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_interactive_attempt,
+           &prev.tcps_mptcp_fp_interactive_attempt, &stat.mptcp_fp_interactive_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_aggregate_attempt,
+           &prev.tcps_mptcp_fp_aggregate_attempt, &stat.mptcp_fp_aggregate_attempt);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_heuristic_fallback,
+           &prev.tcps_mptcp_heuristic_fallback, &stat.mptcp_heuristic_fallback);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_heuristic_fallback,
+           &prev.tcps_mptcp_fp_heuristic_fallback, &stat.mptcp_fp_heuristic_fallback);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_handover_success_wifi,
+           &prev.tcps_mptcp_handover_success_wifi, &stat.mptcp_handover_success_wifi);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_handover_success_cell,
+           &prev.tcps_mptcp_handover_success_cell, &stat.mptcp_handover_success_cell);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_interactive_success,
+           &prev.tcps_mptcp_interactive_success, &stat.mptcp_interactive_success);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_aggregate_success,
+           &prev.tcps_mptcp_aggregate_success, &stat.mptcp_aggregate_success);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_handover_success_wifi,
+           &prev.tcps_mptcp_fp_handover_success_wifi, &stat.mptcp_fp_handover_success_wifi);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_handover_success_cell,
+           &prev.tcps_mptcp_fp_handover_success_cell, &stat.mptcp_fp_handover_success_cell);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_interactive_success,
+           &prev.tcps_mptcp_fp_interactive_success, &stat.mptcp_fp_interactive_success);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_fp_aggregate_success,
+           &prev.tcps_mptcp_fp_aggregate_success, &stat.mptcp_fp_aggregate_success);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_handover_cell_from_wifi,
+           &prev.tcps_mptcp_handover_cell_from_wifi, &stat.mptcp_handover_cell_from_wifi);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_handover_wifi_from_cell,
+           &prev.tcps_mptcp_handover_wifi_from_cell, &stat.mptcp_handover_wifi_from_cell);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_interactive_cell_from_wifi,
+           &prev.tcps_mptcp_interactive_cell_from_wifi, &stat.mptcp_interactive_cell_from_wifi);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_handover_cell_bytes,
+           &prev.tcps_mptcp_handover_cell_bytes, &stat.mptcp_handover_cell_bytes);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_interactive_cell_bytes,
+           &prev.tcps_mptcp_interactive_cell_bytes, &stat.mptcp_interactive_cell_bytes);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_aggregate_cell_bytes,
+           &prev.tcps_mptcp_aggregate_cell_bytes, &stat.mptcp_aggregate_cell_bytes);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_handover_all_bytes,
+           &prev.tcps_mptcp_handover_all_bytes, &stat.mptcp_handover_all_bytes);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_interactive_all_bytes,
+           &prev.tcps_mptcp_interactive_all_bytes, &stat.mptcp_interactive_all_bytes);
+       tcp_cumulative_stat64(tcpstat.tcps_mptcp_aggregate_all_bytes,
+           &prev.tcps_mptcp_aggregate_all_bytes, &stat.mptcp_aggregate_all_bytes);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_back_to_wifi,
+           &prev.tcps_mptcp_back_to_wifi, &stat.mptcp_back_to_wifi);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_wifi_proxy,
+           &prev.tcps_mptcp_wifi_proxy, &stat.mptcp_wifi_proxy);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_cell_proxy,
+           &prev.tcps_mptcp_cell_proxy, &stat.mptcp_cell_proxy);
+       tcp_cumulative_stat(tcpstat.tcps_mptcp_triggered_cell,
+           &prev.tcps_mptcp_triggered_cell, &stat.mptcp_triggered_cell);

 
        nstat_sysinfo_send_data(&data);
 
 
        nstat_sysinfo_send_data(&data);
 

-#undef stat
+#undef  stat
+}
+
+void
+tcp_interface_send_probe(u_int16_t probe_if_index)
+{
+       int32_t offset = 0;
+       struct tcptimerlist *listp = &tcp_timer_list;
+
+       /* Make sure TCP clock is up to date */
+       calculate_tcp_clock();
+
+       lck_mtx_lock(listp->mtx);
+       if (listp->probe_if_index > 0 && listp->probe_if_index != probe_if_index) {
+               tcpstat.tcps_probe_if_conflict++;
+               os_log(OS_LOG_DEFAULT,
+                   "%s: probe_if_index %u conflicts with %u, tcps_probe_if_conflict %u\n",
+                   __func__, probe_if_index, listp->probe_if_index,
+                   tcpstat.tcps_probe_if_conflict);
+               goto done;
+       }
+
+       listp->probe_if_index = probe_if_index;
+       if (listp->running) {
+               os_log(OS_LOG_DEFAULT, "%s: timer list already running for if_index %u\n",
+                   __func__, probe_if_index);
+               goto done;
+       }
+
+       /*
+        * Reschedule the timerlist to run within the next 10ms, which is
+        * the fastest that we can do.
+        */
+       offset = TCP_TIMER_10MS_QUANTUM;
+       if (listp->scheduled) {
+               int32_t diff;
+               diff = timer_diff(listp->runtime, 0, tcp_now, offset);
+               if (diff <= 0) {
+                       /* The timer will fire sooner than what's needed */
+                       os_log(OS_LOG_DEFAULT,
+                           "%s: timer will fire sooner than needed for if_index %u\n",
+                           __func__, probe_if_index);
+                       goto done;
+               }
+       }
+       listp->mode = TCP_TIMERLIST_10MS_MODE;
+       listp->idleruns = 0;
+
+       tcp_sched_timerlist(offset);
+
+done:
+       lck_mtx_unlock(listp->mtx);
+       return;
+}
+
+/*
+ * Enable read probes on this connection, if:
+ * - it is in established state
+ * - doesn't have any data outstanding
+ * - the outgoing ifp matches
+ * - we have not already sent any read probes
+ */
+static void
+tcp_enable_read_probe(struct tcpcb *tp, struct ifnet *ifp)
+{
+       if (tp->t_state == TCPS_ESTABLISHED &&
+           tp->snd_max == tp->snd_una &&
+           tp->t_inpcb->inp_last_outifp == ifp &&
+           !(tp->t_flagsext & TF_DETECT_READSTALL) &&
+           tp->t_rtimo_probes == 0) {
+               tp->t_flagsext |= TF_DETECT_READSTALL;
+               tp->t_rtimo_probes = 0;
+               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,
+                   TCP_TIMER_10MS_QUANTUM);
+               if (tp->tentry.index == TCPT_NONE) {
+                       tp->tentry.index = TCPT_KEEP;
+                       tp->tentry.runtime = tcp_now +
+                           TCP_TIMER_10MS_QUANTUM;
+               } else {
+                       int32_t diff = 0;
+
+                       /* Reset runtime to be in next 10ms */
+                       diff = timer_diff(tp->tentry.runtime, 0,
+                           tcp_now, TCP_TIMER_10MS_QUANTUM);
+                       if (diff > 0) {
+                               tp->tentry.index = TCPT_KEEP;
+                               tp->tentry.runtime = tcp_now +
+                                   TCP_TIMER_10MS_QUANTUM;
+                               if (tp->tentry.runtime == 0) {
+                                       tp->tentry.runtime++;
+                               }
+                       }
+               }
+       }
+}
+
+/*
+ * Disable read probe and reset the keep alive timer
+ */
+static void
+tcp_disable_read_probe(struct tcpcb *tp)
+{
+       if (tp->t_adaptive_rtimo == 0 &&
+           ((tp->t_flagsext & TF_DETECT_READSTALL) ||
+           tp->t_rtimo_probes > 0)) {
+               tcp_keepalive_reset(tp);
+
+               if (tp->t_mpsub) {
+                       mptcp_reset_keepalive(tp);
+               }
+       }
+}
+
+/*
+ * Reschedule the tcp timerlist in the next 10ms to re-enable read/write
+ * probes on connections going over a particular interface.
+ */
+void
+tcp_probe_connectivity(struct ifnet *ifp, u_int32_t enable)
+{
+       int32_t offset;
+       struct tcptimerlist *listp = &tcp_timer_list;
+       struct inpcbinfo *pcbinfo = &tcbinfo;
+       struct inpcb *inp, *nxt;
+
+       if (ifp == NULL) {
+               return;
+       }
+
+       /* update clock */
+       calculate_tcp_clock();
+
+       /*
+        * Enable keep alive timer on all connections that are
+        * active/established on this interface.
+        */
+       lck_rw_lock_shared(pcbinfo->ipi_lock);
+
+       LIST_FOREACH_SAFE(inp, pcbinfo->ipi_listhead, inp_list, nxt) {
+               struct tcpcb *tp = NULL;
+               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) ==
+                   WNT_STOPUSING) {
+                       continue;
+               }
+
+               /* Acquire lock to look at the state of the connection */
+               socket_lock(inp->inp_socket, 1);
+
+               /* Release the want count */
+               if (inp->inp_ppcb == NULL ||
+                   (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING)) {
+                       socket_unlock(inp->inp_socket, 1);
+                       continue;
+               }
+               tp = intotcpcb(inp);
+               if (enable) {
+                       tcp_enable_read_probe(tp, ifp);
+               } else {
+                       tcp_disable_read_probe(tp);
+               }
+
+               socket_unlock(inp->inp_socket, 1);
+       }
+       lck_rw_done(pcbinfo->ipi_lock);
+
+       lck_mtx_lock(listp->mtx);
+       if (listp->running) {
+               listp->pref_mode |= TCP_TIMERLIST_10MS_MODE;
+               goto done;
+       }
+
+       /* Reschedule within the next 10ms */
+       offset = TCP_TIMER_10MS_QUANTUM;
+       if (listp->scheduled) {
+               int32_t diff;
+               diff = timer_diff(listp->runtime, 0, tcp_now, offset);
+               if (diff <= 0) {
+                       /* The timer will fire sooner than what's needed */
+                       goto done;
+               }
+       }
+       listp->mode = TCP_TIMERLIST_10MS_MODE;
+       listp->idleruns = 0;
+
+       tcp_sched_timerlist(offset);
+done:
+       lck_mtx_unlock(listp->mtx);
+       return;
+}
+
+inline void
+tcp_update_mss_core(struct tcpcb *tp, struct ifnet *ifp)
+{
+       struct if_cellular_status_v1 *ifsr;
+       u_int32_t optlen;
+       ifsr = &ifp->if_link_status->ifsr_u.ifsr_cell.if_cell_u.if_status_v1;
+       if (ifsr->valid_bitmask & IF_CELL_UL_MSS_RECOMMENDED_VALID) {
+               optlen = tp->t_maxopd - tp->t_maxseg;
+
+               if (ifsr->mss_recommended ==
+                   IF_CELL_UL_MSS_RECOMMENDED_NONE &&
+                   tp->t_cached_maxopd > 0 &&
+                   tp->t_maxopd < tp->t_cached_maxopd) {
+                       tp->t_maxopd = tp->t_cached_maxopd;
+                       tcpstat.tcps_mss_to_default++;
+               } else if (ifsr->mss_recommended ==
+                   IF_CELL_UL_MSS_RECOMMENDED_MEDIUM &&
+                   tp->t_maxopd > tcp_mss_rec_medium) {
+                       tp->t_cached_maxopd = tp->t_maxopd;
+                       tp->t_maxopd = tcp_mss_rec_medium;
+                       tcpstat.tcps_mss_to_medium++;
+               } else if (ifsr->mss_recommended ==
+                   IF_CELL_UL_MSS_RECOMMENDED_LOW &&
+                   tp->t_maxopd > tcp_mss_rec_low) {
+                       tp->t_cached_maxopd = tp->t_maxopd;
+                       tp->t_maxopd = tcp_mss_rec_low;
+                       tcpstat.tcps_mss_to_low++;
+               }
+               tp->t_maxseg = tp->t_maxopd - optlen;
+
+               /*
+                * clear the cached value if it is same as the current
+                */
+               if (tp->t_maxopd == tp->t_cached_maxopd) {
+                       tp->t_cached_maxopd = 0;
+               }
+       }
+}
+
+void
+tcp_update_mss_locked(struct socket *so, struct ifnet *ifp)
+{
+       struct inpcb *inp = sotoinpcb(so);
+       struct tcpcb *tp = intotcpcb(inp);
+
+       if (ifp == NULL && (ifp = inp->inp_last_outifp) == NULL) {
+               return;
+       }
+
+       if (!IFNET_IS_CELLULAR(ifp)) {
+               /*
+                * This optimization is implemented for cellular
+                * networks only
+                */
+               return;
+       }
+       if (tp->t_state <= TCPS_CLOSE_WAIT) {
+               /*
+                * If the connection is currently doing or has done PMTU
+                * blackhole detection, do not change the MSS
+                */
+               if (tp->t_flags & TF_BLACKHOLE) {
+                       return;
+               }
+               if (ifp->if_link_status == NULL) {
+                       return;
+               }
+               tcp_update_mss_core(tp, ifp);
+       }
+}
+
+void
+tcp_itimer(struct inpcbinfo *ipi)
+{
+       struct inpcb *inp, *nxt;
+
+       if (lck_rw_try_lock_exclusive(ipi->ipi_lock) == FALSE) {
+               if (tcp_itimer_done == TRUE) {
+                       tcp_itimer_done = FALSE;
+                       atomic_add_32(&ipi->ipi_timer_req.intimer_fast, 1);
+                       return;
+               }
+               /* Upgrade failed, lost lock now take it again exclusive */
+               lck_rw_lock_exclusive(ipi->ipi_lock);
+       }
+       tcp_itimer_done = TRUE;
+
+       LIST_FOREACH_SAFE(inp, &tcb, inp_list, nxt) {
+               struct socket *so;
+               struct ifnet *ifp;
+
+               if (inp->inp_ppcb == NULL ||
+                   in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING) {
+                       continue;
+               }
+               so = inp->inp_socket;
+               ifp = inp->inp_last_outifp;
+               socket_lock(so, 1);
+               if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
+                       socket_unlock(so, 1);
+                       continue;
+               }
+               so_check_extended_bk_idle_time(so);
+               if (ipi->ipi_flags & INPCBINFO_UPDATE_MSS) {
+                       tcp_update_mss_locked(so, NULL);
+               }
+               socket_unlock(so, 1);
+
+               /*
+                * Defunct all system-initiated background sockets if the
+                * socket is using the cellular interface and the interface
+                * has its LQM set to abort.
+                */
+               if ((ipi->ipi_flags & INPCBINFO_HANDLE_LQM_ABORT) &&
+                   IS_SO_TC_BACKGROUNDSYSTEM(so->so_traffic_class) &&
+                   ifp != NULL && IFNET_IS_CELLULAR(ifp) &&
+                   (ifp->if_interface_state.valid_bitmask &
+                   IF_INTERFACE_STATE_LQM_STATE_VALID) &&
+                   ifp->if_interface_state.lqm_state ==
+                   IFNET_LQM_THRESH_ABORT) {
+                       socket_defunct(current_proc(), so,
+                           SHUTDOWN_SOCKET_LEVEL_DISCONNECT_ALL);
+               }
+       }
+
+       ipi->ipi_flags &= ~(INPCBINFO_UPDATE_MSS | INPCBINFO_HANDLE_LQM_ABORT);
+       lck_rw_done(ipi->ipi_lock);

 }
 }