]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/netinet/ip_output.c
xnu-4570.31.3.tar.gz
[apple/xnu.git] / bsd / netinet / ip_output.c
index 5f1e3c9804cf4688ee74a4e640a08c70282ad095..f5b51ac5251a76661d22467733c9cd2a2218578e 100644 (file)
@@ -1,23 +1,29 @@
 /*
- * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2017 Apple Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
- * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
- * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * @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
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * 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.
+ *
+ * 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,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
- * 
- * @APPLE_LICENSE_HEADER_END@
+ * 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@
  */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  * SUCH DAMAGE.
  *
  *     @(#)ip_output.c 8.3 (Berkeley) 1/21/94
- * $FreeBSD: src/sys/netinet/ip_output.c,v 1.99.2.16 2001/07/19 06:37:26 kris Exp $
+ */
+/*
+ * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
+ * support for mandatory and extensible security protections.  This notice
+ * is included in support of clause 2.2 (b) of the Apple Public License,
+ * Version 2.0.
  */
 
-#define _IP_VHL
+#define        _IP_VHL
 
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/socketvar.h>
 #include <kern/locks.h>
 #include <sys/sysctl.h>
+#include <sys/mcache.h>
+#include <sys/kdebug.h>
+
+#include <machine/endian.h>
+#include <pexpert/pexpert.h>
+#include <mach/sdt.h>
+
+#include <libkern/OSAtomic.h>
+#include <libkern/OSByteOrder.h>
 
 #include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
 #include <net/route.h>
+#include <net/ntstat.h>
+#include <net/net_osdep.h>
+#include <net/dlil.h>
+#include <net/net_perf.h>
 
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/in_pcb.h>
 #include <netinet/in_var.h>
 #include <netinet/ip_var.h>
-
 #include <netinet/kpi_ipfilter_var.h>
+#include <netinet/in_tclass.h>
 
-#include "faith.h"
-
-#include <net/dlil.h>
-#include <sys/kdebug.h>
+#if CONFIG_MACF_NET
+#include <security/mac_framework.h>
+#endif /* CONFIG_MACF_NET */
 
-#define DBG_LAYER_BEG          NETDBG_CODE(DBG_NETIP, 1)
-#define DBG_LAYER_END          NETDBG_CODE(DBG_NETIP, 3)
-#define DBG_FNC_IP_OUTPUT      NETDBG_CODE(DBG_NETIP, (1 << 8) | 1)
-#define DBG_FNC_IPSEC4_OUTPUT  NETDBG_CODE(DBG_NETIP, (2 << 8) | 1)
-
-#define        SWAP16(v) ((((v) & 0xff) << 8) | ((v) >> 8))
+#define        DBG_LAYER_BEG           NETDBG_CODE(DBG_NETIP, 1)
+#define        DBG_LAYER_END           NETDBG_CODE(DBG_NETIP, 3)
+#define        DBG_FNC_IP_OUTPUT       NETDBG_CODE(DBG_NETIP, (1 << 8) | 1)
+#define        DBG_FNC_IPSEC4_OUTPUT   NETDBG_CODE(DBG_NETIP, (2 << 8) | 1)
 
 #if IPSEC
 #include <netinet6/ipsec.h>
 #if IPSEC_DEBUG
 #include <netkey/key_debug.h>
 #else
-#define        KEYDEBUG(lev,arg)
+#define        KEYDEBUG(lev, arg)
 #endif
-#endif /*IPSEC*/
+#endif /* IPSEC */
 
+#if NECP
+#include <net/necp.h>
+#endif /* NECP */
+
+#if IPFIREWALL
 #include <netinet/ip_fw.h>
+#if IPDIVERT
 #include <netinet/ip_divert.h>
+#endif /* IPDIVERT */
+#endif /* IPFIREWALL */
 
 #if DUMMYNET
 #include <netinet/ip_dummynet.h>
 #endif
 
-#if IPFIREWALL_FORWARD_DEBUG
-#define print_ip(a)     printf("%ld.%ld.%ld.%ld",(ntohl(a.s_addr)>>24)&0xFF,\
-                                                 (ntohl(a.s_addr)>>16)&0xFF,\
-                                                 (ntohl(a.s_addr)>>8)&0xFF,\
-                                                 (ntohl(a.s_addr))&0xFF);
-#endif
+#if PF
+#include <net/pfvar.h>
+#endif /* PF */
 
-#if IPSEC
-extern lck_mtx_t    *sadb_mutex;
-#endif
+#if IPFIREWALL_FORWARD && IPFIREWALL_FORWARD_DEBUG
+#define        print_ip(a)     \
+       printf("%ld.%ld.%ld.%ld", (ntohl(a.s_addr) >> 24) & 0xFF,       \
+           (ntohl(a.s_addr) >> 16) & 0xFF,                             \
+           (ntohl(a.s_addr) >> 8) & 0xFF,                              \
+           (ntohl(a.s_addr)) & 0xFF);
+#endif /* IPFIREWALL_FORWARD && IPFIREWALL_FORWARD_DEBUG */
 
 u_short ip_id;
 
+static int sysctl_reset_ip_output_stats SYSCTL_HANDLER_ARGS;
+static int sysctl_ip_output_measure_bins SYSCTL_HANDLER_ARGS;
+static int sysctl_ip_output_getperf SYSCTL_HANDLER_ARGS;
+static void ip_out_cksum_stats(int, u_int32_t);
 static struct mbuf *ip_insertoptions(struct mbuf *, struct mbuf *, int *);
-static struct ifnet *ip_multicast_if(struct in_addr *, int *);
-static void    ip_mloopback(struct ifnet *, struct mbuf *,
-       struct sockaddr_in *, int);
-static int     ip_getmoptions(struct sockopt *, struct ip_moptions *);
-static int     ip_pcbopts(int, struct mbuf **, struct mbuf *);
-static int     ip_setmoptions(struct sockopt *, struct ip_moptions **);
-
-int ip_createmoptions(struct ip_moptions **imop);
-int ip_addmembership(struct ip_moptions *imo, struct ip_mreq *mreq);
-int ip_dropmembership(struct ip_moptions *imo, struct ip_mreq *mreq);
-int    ip_optcopy(struct ip *, struct ip *);
-extern int (*fr_checkp)(struct ip *, int, struct ifnet *, int, struct mbuf **);
-#ifdef __APPLE__
-extern struct mbuf*    m_dup(register struct mbuf *m, int how);
-#endif
-
-extern int apple_hwcksum_tx;
-extern u_long  route_generation;
-
-extern struct protosw inetsw[];
+static int ip_optcopy(struct ip *, struct ip *);
+static int ip_pcbopts(int, struct mbuf **, struct mbuf *);
+static void imo_trace(struct ip_moptions *, int);
+static void ip_mloopback(struct ifnet *, struct ifnet *, struct mbuf *,
+    struct sockaddr_in *, int);
+static struct ifaddr *in_selectsrcif(struct ip *, struct route *, unsigned int);
 
 extern struct ip_linklocal_stat ip_linklocal_stat;
-extern lck_mtx_t *ip_mutex;
 
 /* temporary: for testing */
 #if IPSEC
 extern int ipsec_bypass;
 #endif
 
-static int     ip_maxchainsent = 0;
-SYSCTL_INT(_net_inet_ip, OID_AUTO, maxchainsent, CTLFLAG_RW,
-    &ip_maxchainsent, 0, "use dlil_output_list");
+static int ip_maxchainsent = 0;
+SYSCTL_INT(_net_inet_ip, OID_AUTO, maxchainsent,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &ip_maxchainsent, 0,
+       "use dlil_output_list");
+#if DEBUG
+static int forge_ce = 0;
+SYSCTL_INT(_net_inet_ip, OID_AUTO, forge_ce,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &forge_ce, 0,
+       "Forge ECN CE");
+#endif /* DEBUG */
+
+static int ip_select_srcif_debug = 0;
+SYSCTL_INT(_net_inet_ip, OID_AUTO, select_srcif_debug,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &ip_select_srcif_debug, 0,
+       "log source interface selection debug info");
+
+static int ip_output_measure = 0;
+SYSCTL_PROC(_net_inet_ip, OID_AUTO, output_perf,
+       CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
+       &ip_output_measure, 0, sysctl_reset_ip_output_stats, "I",
+       "Do time measurement");
+
+static uint64_t ip_output_measure_bins = 0;
+SYSCTL_PROC(_net_inet_ip, OID_AUTO, output_perf_bins,
+       CTLTYPE_QUAD | CTLFLAG_RW | CTLFLAG_LOCKED, &ip_output_measure_bins, 0,
+       sysctl_ip_output_measure_bins, "I",
+       "bins for chaining performance data histogram");
+
+static net_perf_t net_perf;
+SYSCTL_PROC(_net_inet_ip, OID_AUTO, output_perf_data,
+       CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED,
+       0, 0, sysctl_ip_output_getperf, "S,net_perf",
+       "IP output performance data (struct net_perf, net/net_perf.h)");
+
+__private_extern__ int rfc6864 = 1;
+SYSCTL_INT(_net_inet_ip, OID_AUTO, rfc6864, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &rfc6864, 0, "updated ip id field behavior");
+
+#define        IMO_TRACE_HIST_SIZE     32      /* size of trace history */
+
+/* For gdb */
+__private_extern__ unsigned int imo_trace_hist_size = IMO_TRACE_HIST_SIZE;
+
+struct ip_moptions_dbg {
+       struct ip_moptions      imo;                    /* ip_moptions */
+       u_int16_t               imo_refhold_cnt;        /* # of IMO_ADDREF */
+       u_int16_t               imo_refrele_cnt;        /* # of IMO_REMREF */
+       /*
+        * Alloc and free callers.
+        */
+       ctrace_t                imo_alloc;
+       ctrace_t                imo_free;
+       /*
+        * Circular lists of IMO_ADDREF and IMO_REMREF callers.
+        */
+       ctrace_t                imo_refhold[IMO_TRACE_HIST_SIZE];
+       ctrace_t                imo_refrele[IMO_TRACE_HIST_SIZE];
+};
+
+#if DEBUG
+static unsigned int imo_debug = 1;     /* debugging (enabled) */
+#else
+static unsigned int imo_debug;         /* debugging (disabled) */
+#endif /* !DEBUG */
+static unsigned int imo_size;          /* size of zone element */
+static struct zone *imo_zone;          /* zone for ip_moptions */
+
+#define        IMO_ZONE_MAX            64              /* maximum elements in zone */
+#define        IMO_ZONE_NAME           "ip_moptions"   /* zone name */
+
 /*
  * IP output.  The packet in mbuf chain m contains a skeletal IP
  * header (with len, off, ttl, proto, tos, src, dst).
@@ -162,165 +250,371 @@ SYSCTL_INT(_net_inet_ip, OID_AUTO, maxchainsent, CTLFLAG_RW,
  * The mbuf opt, if present, will not be freed.
  */
 int
-ip_output(
-       struct mbuf *m0,
-       struct mbuf *opt,
-       struct route *ro,
-       int flags,
-       struct ip_moptions *imo)
+ip_output(struct mbuf *m0, struct mbuf *opt, struct route *ro, int flags,
+    struct ip_moptions *imo, struct ip_out_args *ipoa)
 {
-       int error;
-       error = ip_output_list(m0, 0, opt, ro, flags, imo);
-       return error;
+       return (ip_output_list(m0, 0, opt, ro, flags, imo, ipoa));
 }
 
+/*
+ * IP output.  The packet in mbuf chain m contains a skeletal IP
+ * header (with len, off, ttl, proto, tos, src, dst).
+ * The mbuf chain containing the packet will be freed.
+ * The mbuf opt, if present, will not be freed.
+ *
+ * Route ro MUST be non-NULL; if ro->ro_rt is valid, route lookup would be
+ * skipped and ro->ro_rt would be used.  Otherwise the result of route
+ * lookup is stored in ro->ro_rt.
+ *
+ * In the IP forwarding case, the packet will arrive with options already
+ * inserted, so must have a NULL opt pointer.
+ */
 int
-ip_output_list(
-       struct mbuf *m0,
-       int packetchain,
-       struct mbuf *opt,
-       struct route *ro,
-       int flags,
-       struct ip_moptions *imo)
+ip_output_list(struct mbuf *m0, int packetchain, struct mbuf *opt,
+    struct route *ro, int flags, struct ip_moptions *imo,
+    struct ip_out_args *ipoa)
 {
-       struct ip *ip, *mhip;
-       struct ifnet *ifp = NULL;
-       struct mbuf *m = m0;
+       struct ip *ip;
+       struct ifnet *ifp = NULL;               /* not refcnt'd */
+       struct mbuf *m = m0, *prevnxt = NULL, **mppn = &prevnxt;
        int hlen = sizeof (struct ip);
-       int len, off, error = 0;
+       int len = 0, error = 0;
        struct sockaddr_in *dst = NULL;
-       struct in_ifaddr *ia = NULL;
-       int isbroadcast, sw_csum;
+       struct in_ifaddr *ia = NULL, *src_ia = NULL;
        struct in_addr pkt_dst;
+       struct ipf_pktopts *ippo = NULL;
+       ipfilter_t inject_filter_ref = NULL;
+       struct mbuf *packetlist;
+       uint32_t sw_csum, pktcnt = 0, scnt = 0, bytecnt = 0;
+       uint32_t packets_processed = 0;
+       unsigned int ifscope = IFSCOPE_NONE;
+       struct flowadv *adv = NULL;
+       struct timeval start_tv;
 #if IPSEC
-       struct route iproute;
        struct socket *so = NULL;
        struct secpolicy *sp = NULL;
-#endif
+#endif /* IPSEC */
+#if NECP
+       necp_kernel_policy_result necp_result = 0;
+       necp_kernel_policy_result_parameter necp_result_parameter;
+       necp_kernel_policy_id necp_matched_policy_id = 0;
+#endif /* NECP */
+#if IPFIREWALL
+       int ipfwoff;
+       struct sockaddr_in *next_hop_from_ipfwd_tag = NULL;
+#endif /* IPFIREWALL */
+#if IPFIREWALL || DUMMYNET
+       struct m_tag *tag;
+#endif /* IPFIREWALL || DUMMYNET */
+#if DUMMYNET
+       struct ip_out_args saved_ipoa;
+       struct sockaddr_in dst_buf;
+#endif /* DUMMYNET */
+       struct {
+#if IPSEC
+               struct ipsec_output_state ipsec_state;
+#endif /* IPSEC */
+#if NECP
+               struct route necp_route;
+#endif /* NECP */
+#if IPFIREWALL || DUMMYNET
+               struct ip_fw_args args;
+#endif /* IPFIREWALL || DUMMYNET */
 #if IPFIREWALL_FORWARD
-       int fwd_rewrite_src = 0;
-#endif
-       struct ip_fw_args args;
-       int didfilter = 0;
-       ipfilter_t inject_filter_ref = 0;
-       struct m_tag    *tag;
-       struct route    dn_route;
-       struct mbuf * packetlist;
-       int pktcnt = 0;
-       
-       lck_mtx_lock(ip_mutex); 
-
-       KERNEL_DEBUG(DBG_FNC_IP_OUTPUT | DBG_FUNC_START, 0,0,0,0,0);
+               struct route sro_fwd;
+#endif /* IPFIREWALL_FORWARD */
+#if DUMMYNET
+               struct route saved_route;
+#endif /* DUMMYNET */
+               struct ipf_pktopts ipf_pktopts;
+       } ipobz;
+#define        ipsec_state     ipobz.ipsec_state
+#define        necp_route      ipobz.necp_route
+#define        args            ipobz.args
+#define        sro_fwd         ipobz.sro_fwd
+#define        saved_route     ipobz.saved_route
+#define        ipf_pktopts     ipobz.ipf_pktopts
+       union {
+               struct {
+                       boolean_t select_srcif : 1;     /* set once */
+                       boolean_t srcbound : 1;         /* set once */
+                       boolean_t nocell : 1;           /* set once */
+                       boolean_t isbroadcast : 1;
+                       boolean_t didfilter : 1;
+                       boolean_t noexpensive : 1;      /* set once */
+                       boolean_t awdl_unrestricted : 1;        /* set once */
+#if IPFIREWALL_FORWARD
+                       boolean_t fwd_rewrite_src : 1;
+#endif /* IPFIREWALL_FORWARD */
+               };
+               uint32_t raw;
+       } ipobf = { .raw = 0 };
+
+/*
+ * Here we check for restrictions when sending frames.
+ * N.B.: IPv4 over internal co-processor interfaces is not allowed.
+ */
+#define        IP_CHECK_RESTRICTIONS(_ifp, _ipobf)                             \
+       (((_ipobf).nocell && IFNET_IS_CELLULAR(_ifp)) ||                \
+        ((_ipobf).noexpensive && IFNET_IS_EXPENSIVE(_ifp)) ||          \
+          (IFNET_IS_INTCOPROC(_ifp)) ||                                        \
+        (!(_ipobf).awdl_unrestricted && IFNET_IS_AWDL_RESTRICTED(_ifp)))
+
+       if (ip_output_measure)
+               net_perf_start_time(&net_perf, &start_tv);
+       KERNEL_DEBUG(DBG_FNC_IP_OUTPUT | DBG_FUNC_START, 0, 0, 0, 0, 0);
 
+       VERIFY(m0->m_flags & M_PKTHDR);
        packetlist = m0;
-       args.eh = NULL;
-       args.rule = NULL;
-       args.next_hop = NULL;
-       args.divert_rule = 0;                   /* divert cookie */
-       
+
+       /* zero out {ipsec_state, args, sro_fwd, saved_route, ipf_pktops} */
+       bzero(&ipobz, sizeof (ipobz));
+       ippo = &ipf_pktopts;
+
+#if IPFIREWALL || DUMMYNET
+       if (SLIST_EMPTY(&m0->m_pkthdr.tags))
+               goto ipfw_tags_done;
+
        /* Grab info from mtags prepended to the chain */
 #if DUMMYNET
-       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_DUMMYNET, NULL)) != NULL) {
+       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID,
+           KERNEL_TAG_TYPE_DUMMYNET, NULL)) != NULL) {
                struct dn_pkt_tag       *dn_tag;
-               
+
                dn_tag = (struct dn_pkt_tag *)(tag+1);
-               args.rule = dn_tag->rule;
+               args.fwa_ipfw_rule = dn_tag->dn_ipfw_rule;
+               args.fwa_pf_rule = dn_tag->dn_pf_rule;
                opt = NULL;
-               dn_route = dn_tag->ro;
-               ro = &dn_route;
-                       
+               saved_route = dn_tag->dn_ro;
+               ro = &saved_route;
+
                imo = NULL;
-               dst = dn_tag->dn_dst;
-               ifp = dn_tag->ifp;
-               flags = dn_tag->flags;
-               
+               bcopy(&dn_tag->dn_dst, &dst_buf, sizeof (dst_buf));
+               dst = &dst_buf;
+               ifp = dn_tag->dn_ifp;
+               flags = dn_tag->dn_flags;
+               if ((dn_tag->dn_flags & IP_OUTARGS)) {
+                       saved_ipoa = dn_tag->dn_ipoa;
+                       ipoa = &saved_ipoa;
+               }
+
                m_tag_delete(m0, tag);
        }
 #endif /* DUMMYNET */
 
-       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_DIVERT, NULL)) != NULL) {
+#if IPDIVERT
+       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID,
+           KERNEL_TAG_TYPE_DIVERT, NULL)) != NULL) {
                struct divert_tag       *div_tag;
-               
+
                div_tag = (struct divert_tag *)(tag+1);
-               args.divert_rule = div_tag->cookie;
+               args.fwa_divert_rule = div_tag->cookie;
 
                m_tag_delete(m0, tag);
        }
-       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_IPFORWARD, NULL)) != NULL) {
+#endif /* IPDIVERT */
+
+#if IPFIREWALL
+       if ((tag = m_tag_locate(m0, KERNEL_MODULE_TAG_ID,
+           KERNEL_TAG_TYPE_IPFORWARD, NULL)) != NULL) {
                struct ip_fwd_tag       *ipfwd_tag;
-               
+
                ipfwd_tag = (struct ip_fwd_tag *)(tag+1);
-               args.next_hop = ipfwd_tag->next_hop;
-               
+               next_hop_from_ipfwd_tag = ipfwd_tag->next_hop;
+
                m_tag_delete(m0, tag);
        }
+#endif /* IPFIREWALL */
+
+ipfw_tags_done:
+#endif /* IPFIREWALL || DUMMYNET */
 
        m = m0;
-       
-#if    DIAGNOSTIC
-       if ( !m || (m->m_flags & M_PKTHDR) != 0)
-               panic("ip_output no HDR");
-       if (!ro)
-               panic("ip_output no route, proto = %d",
-                     mtod(m, struct ip *)->ip_p);
-#endif
+       m->m_pkthdr.pkt_flags &= ~(PKTF_LOOP|PKTF_IFAINFO);
 
-       if (args.rule != NULL) {        /* dummynet already saw us */
-            ip = mtod(m, struct ip *);
-            hlen = IP_VHL_HL(ip->ip_vhl) << 2 ;
-            if (ro->ro_rt != NULL)
-                ia = (struct in_ifaddr *)ro->ro_rt->rt_ifa;
-                       if (ia)
-                               ifaref(&ia->ia_ifa);
 #if IPSEC
-                       if (ipsec_bypass == 0 && (flags & IP_NOIPSEC) == 0) {
-                               so = ipsec_getsocket(m);
-                               (void)ipsec_setsocket(m, NULL);
-                       }
-#endif
-            goto sendit;
+       if (ipsec_bypass == 0 && !(flags & IP_NOIPSEC)) {
+               /* If packet is bound to an interface, check bound policies */
+               if ((flags & IP_OUTARGS) && (ipoa != NULL) &&
+                       (ipoa->ipoa_flags & IPOAF_BOUND_IF) &&
+                       ipoa->ipoa_boundif != IFSCOPE_NONE) {
+                       if (ipsec4_getpolicybyinterface(m, IPSEC_DIR_OUTBOUND,
+                               &flags, ipoa, &sp) != 0)
+                               goto bad;
+               }
+       }
+#endif /* IPSEC */
+
+       VERIFY(ro != NULL);
+
+       if (flags & IP_OUTARGS) {
+               /*
+                * In the forwarding case, only the ifscope value is used,
+                * as source interface selection doesn't take place.
+                */
+               if ((ipobf.select_srcif = (!(flags & IP_FORWARDING) &&
+                   (ipoa->ipoa_flags & IPOAF_SELECT_SRCIF)))) {
+                       ipf_pktopts.ippo_flags |= IPPOF_SELECT_SRCIF;
+               }
+
+               if ((ipoa->ipoa_flags & IPOAF_BOUND_IF) &&
+                   ipoa->ipoa_boundif != IFSCOPE_NONE) {
+                       ifscope = ipoa->ipoa_boundif;
+                       ipf_pktopts.ippo_flags |=
+                           (IPPOF_BOUND_IF | (ifscope << IPPOF_SHIFT_IFSCOPE));
+               }
+
+               /* double negation needed for bool bit field */
+               ipobf.srcbound = !!(ipoa->ipoa_flags & IPOAF_BOUND_SRCADDR);
+               if (ipobf.srcbound)
+                       ipf_pktopts.ippo_flags |= IPPOF_BOUND_SRCADDR;
+       } else {
+               ipobf.select_srcif = FALSE;
+               ipobf.srcbound = FALSE;
+               ifscope = IFSCOPE_NONE;
+               if (flags & IP_OUTARGS) {
+                       ipoa->ipoa_boundif = IFSCOPE_NONE;
+                       ipoa->ipoa_flags &= ~(IPOAF_SELECT_SRCIF |
+                           IPOAF_BOUND_IF | IPOAF_BOUND_SRCADDR);
+               }
+       }
+
+       if (flags & IP_OUTARGS) {
+               if (ipoa->ipoa_flags & IPOAF_NO_CELLULAR) {
+                       ipobf.nocell = TRUE;
+                       ipf_pktopts.ippo_flags |= IPPOF_NO_IFT_CELLULAR;
+               }
+               if (ipoa->ipoa_flags & IPOAF_NO_EXPENSIVE) {
+                       ipobf.noexpensive = TRUE;
+                       ipf_pktopts.ippo_flags |= IPPOF_NO_IFF_EXPENSIVE;
+               }
+               if (ipoa->ipoa_flags & IPOAF_AWDL_UNRESTRICTED)
+                       ipobf.awdl_unrestricted = TRUE;
+               adv = &ipoa->ipoa_flowadv;
+               adv->code = FADV_SUCCESS;
+               ipoa->ipoa_retflags = 0;
        }
 
 #if IPSEC
-       if (ipsec_bypass == 0 && (flags & IP_NOIPSEC) == 0) {
+       if (ipsec_bypass == 0 && !(flags & IP_NOIPSEC)) {
                so = ipsec_getsocket(m);
-               (void)ipsec_setsocket(m, NULL);
+               if (so != NULL) {
+                       (void) ipsec_setsocket(m, NULL);
+               }
        }
-#endif
-loopit:        
+#endif /* IPSEC */
+
+#if DUMMYNET
+       if (args.fwa_ipfw_rule != NULL || args.fwa_pf_rule != NULL) {
+               /* dummynet already saw us */
+               ip = mtod(m, struct ip *);
+               hlen = IP_VHL_HL(ip->ip_vhl) << 2;
+               pkt_dst = ip->ip_dst;
+               if (ro->ro_rt != NULL) {
+                       RT_LOCK_SPIN(ro->ro_rt);
+                       ia = (struct in_ifaddr *)ro->ro_rt->rt_ifa;
+                       if (ia) {
+                               /* Become a regular mutex */
+                               RT_CONVERT_LOCK(ro->ro_rt);
+                               IFA_ADDREF(&ia->ia_ifa);
+                       }
+                       RT_UNLOCK(ro->ro_rt);
+               }
+
+#if IPFIREWALL
+               if (args.fwa_ipfw_rule != NULL)
+                       goto skip_ipsec;
+#endif /* IPFIREWALL  */
+               if (args.fwa_pf_rule != NULL)
+                       goto sendit;
+       }
+#endif /* DUMMYNET */
+
+loopit:
+       packets_processed++;
+       ipobf.isbroadcast = FALSE;
+       ipobf.didfilter = FALSE;
+#if IPFIREWALL_FORWARD
+       ipobf.fwd_rewrite_src = FALSE;
+#endif /* IPFIREWALL_FORWARD */
+
+       VERIFY(m->m_flags & M_PKTHDR);
        /*
-        * No need to proccess packet twice if we've 
-        * already seen it
+        * No need to proccess packet twice if we've already seen it.
         */
-       inject_filter_ref = ipf_get_inject_filter(m);
+       if (!SLIST_EMPTY(&m->m_pkthdr.tags))
+               inject_filter_ref = ipf_get_inject_filter(m);
+       else
+               inject_filter_ref = NULL;
 
        if (opt) {
                m = ip_insertoptions(m, opt, &len);
                hlen = len;
+               /* Update the chain */
+               if (m != m0) {
+                       if (m0 == packetlist)
+                               packetlist = m;
+                       m0 = m;
+               }
        }
        ip = mtod(m, struct ip *);
-       pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst;
+
+#if IPFIREWALL
+       /*
+        * rdar://8542331
+        *
+        * When dealing with a packet chain, we need to reset "next_hop"
+        * because "dst" may have been changed to the gateway address below
+        * for the previous packet of the chain. This could cause the route
+        * to be inavertandly changed to the route to the gateway address
+        * (instead of the route to the destination).
+        */
+       args.fwa_next_hop = next_hop_from_ipfwd_tag;
+       pkt_dst = args.fwa_next_hop ? args.fwa_next_hop->sin_addr : ip->ip_dst;
+#else /* !IPFIREWALL */
+       pkt_dst = ip->ip_dst;
+#endif /* !IPFIREWALL */
+
+       /*
+        * We must not send if the packet is destined to network zero.
+        * RFC1122 3.2.1.3 (a) and (b).
+        */
+       if (IN_ZERONET(ntohl(pkt_dst.s_addr))) {
+               error = EHOSTUNREACH;
+               goto bad;
+       }
 
        /*
         * Fill in IP header.
         */
-       if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
+       if (!(flags & (IP_FORWARDING|IP_RAWOUTPUT))) {
                ip->ip_vhl = IP_MAKE_VHL(IPVERSION, hlen >> 2);
                ip->ip_off &= IP_DF;
-#if RANDOM_IP_ID
-               ip->ip_id = ip_randomid();
-#else
-               ip->ip_id = htons(ip_id++);
-#endif
-               ipstat.ips_localout++;
+               if (rfc6864 && IP_OFF_IS_ATOMIC(ip->ip_off)) {
+                       // Per RFC6864, value of ip_id is undefined for atomic ip packets
+                       ip->ip_id = 0;
+               } else {
+                       ip->ip_id = ip_randomid();
+               }
+               OSAddAtomic(1, &ipstat.ips_localout);
        } else {
                hlen = IP_VHL_HL(ip->ip_vhl) << 2;
        }
 
-       KERNEL_DEBUG(DBG_LAYER_BEG, ip->ip_dst.s_addr, 
-                    ip->ip_src.s_addr, ip->ip_p, ip->ip_off, ip->ip_len);
+#if DEBUG
+       /* For debugging, we let the stack forge congestion */
+       if (forge_ce != 0 &&
+           ((ip->ip_tos & IPTOS_ECN_MASK) == IPTOS_ECN_ECT1 ||
+           (ip->ip_tos & IPTOS_ECN_MASK) == IPTOS_ECN_ECT0)) {
+               ip->ip_tos = (ip->ip_tos & ~IPTOS_ECN_MASK) | IPTOS_ECN_CE;
+               forge_ce--;
+       }
+#endif /* DEBUG */
 
-       dst = (struct sockaddr_in *)&ro->ro_dst;
+       KERNEL_DEBUG(DBG_LAYER_BEG, ip->ip_dst.s_addr, ip->ip_src.s_addr,
+           ip->ip_p, ip->ip_off, ip->ip_len);
+
+       dst = SIN(&ro->ro_dst);
 
        /*
         * If there is a cached route,
@@ -330,46 +624,152 @@ loopit:
         * cache with IPv6.
         */
 
-       {
-               if (ro->ro_rt && (ro->ro_rt->generation_id != route_generation) &&
-                       ((flags & (IP_ROUTETOIF | IP_FORWARDING)) == 0) && (ip->ip_src.s_addr != INADDR_ANY) &&
-                       (ifa_foraddr(ip->ip_src.s_addr) == 0)) {
-                       error = EADDRNOTAVAIL;
-                       goto bad;
+       if (ro->ro_rt != NULL) {
+               if (ROUTE_UNUSABLE(ro) && ip->ip_src.s_addr != INADDR_ANY &&
+                   !(flags & (IP_ROUTETOIF | IP_FORWARDING))) {
+                       src_ia = ifa_foraddr(ip->ip_src.s_addr);
+                       if (src_ia == NULL) {
+                               error = EADDRNOTAVAIL;
+                               goto bad;
+                       }
+                       IFA_REMREF(&src_ia->ia_ifa);
+                       src_ia = NULL;
                }
+               /*
+                * Test rt_flags without holding rt_lock for performance
+                * reasons; if the route is down it will hopefully be
+                * caught by the layer below (since it uses this route
+                * as a hint) or during the next transmit.
+                */
+               if (ROUTE_UNUSABLE(ro) || dst->sin_family != AF_INET ||
+                   dst->sin_addr.s_addr != pkt_dst.s_addr)
+                       ROUTE_RELEASE(ro);
+
+               /*
+                * If we're doing source interface selection, we may not
+                * want to use this route; only synch up the generation
+                * count otherwise.
+                */
+               if (!ipobf.select_srcif && ro->ro_rt != NULL &&
+                   RT_GENID_OUTOFSYNC(ro->ro_rt))
+                       RT_GENID_SYNC(ro->ro_rt);
        }
-       if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
-          dst->sin_family != AF_INET ||
-          dst->sin_addr.s_addr != pkt_dst.s_addr)) {
-               rtfree(ro->ro_rt);
-               ro->ro_rt = (struct rtentry *)0;
-       }
-       if (ro->ro_rt == 0) {
-               bzero(dst, sizeof(*dst));
+       if (ro->ro_rt == NULL) {
+               bzero(dst, sizeof (*dst));
                dst->sin_family = AF_INET;
-               dst->sin_len = sizeof(*dst);
+               dst->sin_len = sizeof (*dst);
                dst->sin_addr = pkt_dst;
        }
        /*
         * If routing to interface only,
         * short circuit routing lookup.
         */
-#define ifatoia(ifa)   ((struct in_ifaddr *)(ifa))
-#define sintosa(sin)   ((struct sockaddr *)(sin))
        if (flags & IP_ROUTETOIF) {
-               if (ia)
-                       ifafree(&ia->ia_ifa);
-               if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == 0) {
-                       if ((ia = ifatoia(ifa_ifwithnet(sintosa(dst)))) == 0) {
-                               ipstat.ips_noroute++;
+               if (ia != NULL)
+                       IFA_REMREF(&ia->ia_ifa);
+               if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
+                       ia = ifatoia(ifa_ifwithnet(sintosa(dst)));
+                       if (ia == NULL) {
+                               OSAddAtomic(1, &ipstat.ips_noroute);
                                error = ENETUNREACH;
+                               /* XXX IPv6 APN fallback notification?? */
                                goto bad;
                        }
                }
                ifp = ia->ia_ifp;
                ip->ip_ttl = 1;
-               isbroadcast = in_broadcast(dst->sin_addr, ifp);
+               ipobf.isbroadcast = in_broadcast(dst->sin_addr, ifp);
+               /*
+                * For consistency with other cases below.  Loopback
+                * multicast case is handled separately by ip_mloopback().
+                */
+               if ((ifp->if_flags & IFF_LOOPBACK) &&
+                   !IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
+                       m->m_pkthdr.rcvif = ifp;
+                       ip_setsrcifaddr_info(m, ifp->if_index, NULL);
+                       ip_setdstifaddr_info(m, ifp->if_index, NULL);
+               }
+       } else if (IN_MULTICAST(ntohl(pkt_dst.s_addr)) &&
+           imo != NULL && (ifp = imo->imo_multicast_ifp) != NULL) {
+               /*
+                * Bypass the normal routing lookup for multicast
+                * packets if the interface is specified.
+                */
+               ipobf.isbroadcast = FALSE;
+               if (ia != NULL)
+                       IFA_REMREF(&ia->ia_ifa);
+
+               /* Macro takes reference on ia */
+               IFP_TO_IA(ifp, ia);
        } else {
+               struct ifaddr *ia0 = NULL;
+               boolean_t cloneok = FALSE;
+               /*
+                * Perform source interface selection; the source IP address
+                * must belong to one of the addresses of the interface used
+                * by the route.  For performance reasons, do this only if
+                * there is no route, or if the routing table has changed,
+                * or if we haven't done source interface selection on this
+                * route (for this PCB instance) before.
+                */
+               if (ipobf.select_srcif &&
+                   ip->ip_src.s_addr != INADDR_ANY && (ROUTE_UNUSABLE(ro) ||
+                   !(ro->ro_flags & ROF_SRCIF_SELECTED))) {
+                       /* Find the source interface */
+                       ia0 = in_selectsrcif(ip, ro, ifscope);
+
+                       /*
+                        * If the source address belongs to a restricted
+                        * interface and the caller forbids our using
+                        * interfaces of such type, pretend that there is no
+                        * route.
+                        */
+                       if (ia0 != NULL &&
+                           IP_CHECK_RESTRICTIONS(ia0->ifa_ifp, ipobf)) {
+                               IFA_REMREF(ia0);
+                               ia0 = NULL;
+                               error = EHOSTUNREACH;
+                               if (flags & IP_OUTARGS)
+                                       ipoa->ipoa_retflags |= IPOARF_IFDENIED;
+                               goto bad;
+                       }
+
+                       /*
+                        * If the source address is spoofed (in the case of
+                        * IP_RAWOUTPUT on an unbounded socket), or if this
+                        * is destined for local/loopback, just let it go out
+                        * using the interface of the route.  Otherwise,
+                        * there's no interface having such an address,
+                        * so bail out.
+                        */
+                       if (ia0 == NULL && (!(flags & IP_RAWOUTPUT) ||
+                           ipobf.srcbound) && ifscope != lo_ifp->if_index) {
+                               error = EADDRNOTAVAIL;
+                               goto bad;
+                       }
+
+                       /*
+                        * If the caller didn't explicitly specify the scope,
+                        * pick it up from the source interface.  If the cached
+                        * route was wrong and was blown away as part of source
+                        * interface selection, don't mask out RTF_PRCLONING
+                        * since that route may have been allocated by the ULP,
+                        * unless the IP header was created by the caller or
+                        * the destination is IPv4 LLA.  The check for the
+                        * latter is needed because IPv4 LLAs are never scoped
+                        * in the current implementation, and we don't want to
+                        * replace the resolved IPv4 LLA route with one whose
+                        * gateway points to that of the default gateway on
+                        * the primary interface of the system.
+                        */
+                       if (ia0 != NULL) {
+                               if (ifscope == IFSCOPE_NONE)
+                                       ifscope = ia0->ifa_ifp->if_index;
+                               cloneok = (!(flags & IP_RAWOUTPUT) &&
+                                   !(IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))));
+                       }
+               }
+
                /*
                 * If this is the case, we probably don't want to allocate
                 * a protocol-cloned route since we didn't get one from the
@@ -379,29 +779,140 @@ loopit:
                 * the link layer, as this is probably required in all cases
                 * for correct operation (as it is for ARP).
                 */
-               if (ro->ro_rt == 0)
-                       rtalloc_ign(ro, RTF_PRCLONING);
-               if (ro->ro_rt == 0) {
-                       ipstat.ips_noroute++;
+               if (ro->ro_rt == NULL) {
+                       unsigned long ign = RTF_PRCLONING;
+                       /*
+                        * We make an exception here: if the destination
+                        * address is INADDR_BROADCAST, allocate a protocol-
+                        * cloned host route so that we end up with a route
+                        * marked with the RTF_BROADCAST flag.  Otherwise,
+                        * we would end up referring to the default route,
+                        * instead of creating a cloned host route entry.
+                        * That would introduce inconsistencies between ULPs
+                        * that allocate a route and those that don't.  The
+                        * RTF_BROADCAST route is important since we'd want
+                        * to send out undirected IP broadcast packets using
+                        * link-level broadcast address. Another exception
+                        * is for ULP-created routes that got blown away by
+                        * source interface selection (see above).
+                        *
+                        * These exceptions will no longer be necessary when
+                        * the RTF_PRCLONING scheme is no longer present.
+                        */
+                       if (cloneok || dst->sin_addr.s_addr == INADDR_BROADCAST)
+                               ign &= ~RTF_PRCLONING;
+
+                       /*
+                        * Loosen the route lookup criteria if the ifscope
+                        * corresponds to the loopback interface; this is
+                        * needed to support Application Layer Gateways
+                        * listening on loopback, in conjunction with packet
+                        * filter redirection rules.  The final source IP
+                        * address will be rewritten by the packet filter
+                        * prior to the RFC1122 loopback check below.
+                        */
+                       if (ifscope == lo_ifp->if_index)
+                               rtalloc_ign(ro, ign);
+                       else
+                               rtalloc_scoped_ign(ro, ign, ifscope);
+
+                       /*
+                        * If the route points to a cellular/expensive interface
+                        * and the caller forbids our using interfaces of such type,
+                        * pretend that there is no route.
+                        */
+                       if (ro->ro_rt != NULL) {
+                               RT_LOCK_SPIN(ro->ro_rt);
+                               if (IP_CHECK_RESTRICTIONS(ro->ro_rt->rt_ifp,
+                                   ipobf)) {
+                                       RT_UNLOCK(ro->ro_rt);
+                                       ROUTE_RELEASE(ro);
+                                       if (flags & IP_OUTARGS) {
+                                               ipoa->ipoa_retflags |=
+                                                   IPOARF_IFDENIED;
+                                       }
+                               } else {
+                                       RT_UNLOCK(ro->ro_rt);
+                               }
+                       }
+               }
+
+               if (ro->ro_rt == NULL) {
+                       OSAddAtomic(1, &ipstat.ips_noroute);
                        error = EHOSTUNREACH;
+                       if (ia0 != NULL) {
+                               IFA_REMREF(ia0);
+                               ia0 = NULL;
+                       }
                        goto bad;
                }
-               if (ia)
-                       ifafree(&ia->ia_ifa);
+
+               if (ia != NULL)
+                       IFA_REMREF(&ia->ia_ifa);
+               RT_LOCK_SPIN(ro->ro_rt);
                ia = ifatoia(ro->ro_rt->rt_ifa);
-               if (ia)
-                       ifaref(&ia->ia_ifa);
+               if (ia != NULL) {
+                       /* Become a regular mutex */
+                       RT_CONVERT_LOCK(ro->ro_rt);
+                       IFA_ADDREF(&ia->ia_ifa);
+               }
+               /*
+                * Note: ia_ifp may not be the same as rt_ifp; the latter
+                * is what we use for determining outbound i/f, mtu, etc.
+                */
                ifp = ro->ro_rt->rt_ifp;
                ro->ro_rt->rt_use++;
-               if (ro->ro_rt->rt_flags & RTF_GATEWAY)
-                       dst = (struct sockaddr_in *)ro->ro_rt->rt_gateway;
-               if (ro->ro_rt->rt_flags & RTF_HOST)
-                       isbroadcast = (ro->ro_rt->rt_flags & RTF_BROADCAST);
-               else
-                       isbroadcast = in_broadcast(dst->sin_addr, ifp);
+               if (ro->ro_rt->rt_flags & RTF_GATEWAY) {
+                       dst = SIN(ro->ro_rt->rt_gateway);
+               }
+               if (ro->ro_rt->rt_flags & RTF_HOST) {
+                       /* double negation needed for bool bit field */
+                       ipobf.isbroadcast =
+                           !!(ro->ro_rt->rt_flags & RTF_BROADCAST);
+               } else {
+                       /* Become a regular mutex */
+                       RT_CONVERT_LOCK(ro->ro_rt);
+                       ipobf.isbroadcast = in_broadcast(dst->sin_addr, ifp);
+               }
+               /*
+                * For consistency with IPv6, as well as to ensure that
+                * IP_RECVIF is set correctly for packets that are sent
+                * to one of the local addresses.  ia (rt_ifa) would have
+                * been fixed up by rt_setif for local routes.  This
+                * would make it appear as if the packet arrives on the
+                * interface which owns the local address.  Loopback
+                * multicast case is handled separately by ip_mloopback().
+                */
+               if (ia != NULL && (ifp->if_flags & IFF_LOOPBACK) &&
+                   !IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
+                       uint32_t srcidx;
+
+                       m->m_pkthdr.rcvif = ia->ia_ifa.ifa_ifp;
+
+                       if (ia0 != NULL)
+                               srcidx = ia0->ifa_ifp->if_index;
+                       else if ((ro->ro_flags & ROF_SRCIF_SELECTED) &&
+                           ro->ro_srcia != NULL)
+                               srcidx = ro->ro_srcia->ifa_ifp->if_index;
+                       else
+                               srcidx = 0;
+
+                       ip_setsrcifaddr_info(m, srcidx, NULL);
+                       ip_setdstifaddr_info(m, 0, ia);
+               }
+               RT_UNLOCK(ro->ro_rt);
+               if (ia0 != NULL) {
+                       IFA_REMREF(ia0);
+                       ia0 = NULL;
+               }
        }
+
        if (IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
+               struct ifnet *srcifp = NULL;
                struct in_multi *inm;
+               u_int32_t vif = 0;
+               u_int8_t ttl = IP_DEFAULT_MULTICAST_TTL;
+               u_int8_t loop = IP_DEFAULT_MULTICAST_LOOP;
 
                m->m_flags |= M_MCAST;
                /*
@@ -409,27 +920,30 @@ loopit:
                 * still points to the address in "ro".  (It may have been
                 * changed to point to a gateway address, above.)
                 */
-               dst = (struct sockaddr_in *)&ro->ro_dst;
+               dst = SIN(&ro->ro_dst);
                /*
                 * See if the caller provided any multicast options
                 */
                if (imo != NULL) {
-                       if ((flags & IP_RAWOUTPUT) == 0) ip->ip_ttl = imo->imo_multicast_ttl;
-                       if (imo->imo_multicast_ifp != NULL) {
+                       IMO_LOCK(imo);
+                       vif = imo->imo_multicast_vif;
+                       ttl = imo->imo_multicast_ttl;
+                       loop = imo->imo_multicast_loop;
+                       if (!(flags & IP_RAWOUTPUT))
+                               ip->ip_ttl = ttl;
+                       if (imo->imo_multicast_ifp != NULL)
                                ifp = imo->imo_multicast_ifp;
-                       }
-                       if (imo->imo_multicast_vif != -1 && 
-                               ((flags & IP_RAWOUTPUT) == 0 || ip->ip_src.s_addr == INADDR_ANY))
-                               ip->ip_src.s_addr =
-                                       ip_mcast_src(imo->imo_multicast_vif);
-               } else
-                       if ((flags & IP_RAWOUTPUT) == 0) ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
+                       IMO_UNLOCK(imo);
+               } else if (!(flags & IP_RAWOUTPUT)) {
+                       vif = -1;
+                       ip->ip_ttl = ttl;
+               }
                /*
                 * Confirm that the outgoing interface supports multicast.
                 */
-               if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
-                       if ((ifp->if_flags & IFF_MULTICAST) == 0) {
-                               ipstat.ips_noroute++;
+               if (imo == NULL || vif == -1) {
+                       if (!(ifp->if_flags & IFF_MULTICAST)) {
+                               OSAddAtomic(1, &ipstat.ips_noroute);
                                error = ENETUNREACH;
                                goto bad;
                        }
@@ -439,25 +953,29 @@ loopit:
                 * of outgoing interface.
                 */
                if (ip->ip_src.s_addr == INADDR_ANY) {
-                       register struct in_ifaddr *ia1;
-
-                       TAILQ_FOREACH(ia1, &in_ifaddrhead, ia_link)
+                       struct in_ifaddr *ia1;
+                       lck_rw_lock_shared(in_ifaddr_rwlock);
+                       TAILQ_FOREACH(ia1, &in_ifaddrhead, ia_link) {
+                               IFA_LOCK_SPIN(&ia1->ia_ifa);
                                if (ia1->ia_ifp == ifp) {
                                        ip->ip_src = IA_SIN(ia1)->sin_addr;
-                                       
+                                       srcifp = ifp;
+                                       IFA_UNLOCK(&ia1->ia_ifa);
                                        break;
                                }
+                               IFA_UNLOCK(&ia1->ia_ifa);
+                       }
+                       lck_rw_done(in_ifaddr_rwlock);
                        if (ip->ip_src.s_addr == INADDR_ANY) {
                                error = ENETUNREACH;
                                goto bad;
                        }
                }
 
-               ifnet_lock_shared(ifp);
-               IN_LOOKUP_MULTI(pkt_dst, ifp, inm);
-               ifnet_lock_done(ifp);
-               if (inm != NULL &&
-                  (imo == NULL || imo->imo_multicast_loop)) {
+               in_multihead_lock_shared();
+               IN_LOOKUP_MULTI(&pkt_dst, ifp, inm);
+               in_multihead_lock_done();
+               if (inm != NULL && (imo == NULL || loop)) {
                        /*
                         * If we belong to the destination multicast group
                         * on the outgoing interface, and the caller did not
@@ -465,83 +983,64 @@ loopit:
                         */
                        if (!TAILQ_EMPTY(&ipv4_filters)) {
                                struct ipfilter *filter;
-                               int seen = (inject_filter_ref == 0);
-                               struct ipf_pktopts *ippo = 0, ipf_pktopts;
-
-                               if (imo) {                                              
-                                       ippo = &ipf_pktopts;
-                                       ipf_pktopts.ippo_mcast_ifnet = imo->imo_multicast_ifp;
-                                       ipf_pktopts.ippo_mcast_ttl = imo->imo_multicast_ttl;
-                                       ipf_pktopts.ippo_mcast_loop = imo->imo_multicast_loop;
+                               int seen = (inject_filter_ref == NULL);
+
+                               if (imo != NULL) {
+                                       ipf_pktopts.ippo_flags |=
+                                           IPPOF_MCAST_OPTS;
+                                       ipf_pktopts.ippo_mcast_ifnet = ifp;
+                                       ipf_pktopts.ippo_mcast_ttl = ttl;
+                                       ipf_pktopts.ippo_mcast_loop = loop;
                                }
-                               
-                               lck_mtx_unlock(ip_mutex);
+
                                ipf_ref();
-                               
-                               /* 4135317 - always pass network byte order to filter */
+
+                               /*
+                                * 4135317 - always pass network byte
+                                * order to filter
+                                */
+#if BYTE_ORDER != BIG_ENDIAN
                                HTONS(ip->ip_len);
                                HTONS(ip->ip_off);
-                               
+#endif
                                TAILQ_FOREACH(filter, &ipv4_filters, ipf_link) {
                                        if (seen == 0) {
-                                               if ((struct ipfilter *)inject_filter_ref == filter)
+                                               if ((struct ipfilter *)
+                                                   inject_filter_ref == filter)
                                                        seen = 1;
-                                       } else if (filter->ipf_filter.ipf_output) {
+                                       } else if (filter->ipf_filter.
+                                           ipf_output != NULL) {
                                                errno_t result;
-                                               result = filter->ipf_filter.ipf_output(filter->ipf_filter.cookie, (mbuf_t*)&m, ippo);
+                                               result = filter->ipf_filter.
+                                                   ipf_output(filter->
+                                                   ipf_filter.cookie,
+                                                   (mbuf_t *)&m, ippo);
                                                if (result == EJUSTRETURN) {
                                                        ipf_unref();
+                                                       INM_REMREF(inm);
                                                        goto done;
                                                }
                                                if (result != 0) {
                                                        ipf_unref();
-                                                       lck_mtx_lock(ip_mutex);
+                                                       INM_REMREF(inm);
                                                        goto bad;
                                                }
                                        }
                                }
-                               
+
                                /* set back to host byte order */
                                ip = mtod(m, struct ip *);
+#if BYTE_ORDER != BIG_ENDIAN
                                NTOHS(ip->ip_len);
                                NTOHS(ip->ip_off);
-                               
-                               lck_mtx_lock(ip_mutex);
+#endif
                                ipf_unref();
-                               didfilter = 1;
-                       }
-                       ip_mloopback(ifp, m, dst, hlen);
-               }
-               else {
-                       /*
-                        * If we are acting as a multicast router, perform
-                        * multicast forwarding as if the packet had just
-                        * arrived on the interface to which we are about
-                        * to send.  The multicast forwarding function
-                        * recursively calls this function, using the
-                        * IP_FORWARDING flag to prevent infinite recursion.
-                        *
-                        * Multicasts that are looped back by ip_mloopback(),
-                        * above, will be forwarded by the ip_input() routine,
-                        * if necessary.
-                        */
-                       if (ip_mrouter && (flags & IP_FORWARDING) == 0) {
-                               /*
-                                * Check if rsvp daemon is running. If not, don't
-                                * set ip_moptions. This ensures that the packet
-                                * is multicast and not just sent down one link
-                                * as prescribed by rsvpd.
-                                */
-                               if (!rsvp_on)
-                                 imo = NULL;
-                               if (ip_mforward(ip, ifp, m, imo) != 0) {
-                                       m_freem(m);
-                                       lck_mtx_unlock(ip_mutex);
-                                       goto done;
-                               }
+                               ipobf.didfilter = TRUE;
                        }
+                       ip_mloopback(srcifp, ifp, m, dst, hlen);
                }
-
+               if (inm != NULL)
+                       INM_REMREF(inm);
                /*
                 * Multicasts with a time-to-live of zero may be looped-
                 * back, above, but must not be transmitted on a network.
@@ -552,41 +1051,41 @@ loopit:
                 */
                if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
                        m_freem(m);
-                       lck_mtx_unlock(ip_mutex);
                        goto done;
                }
 
                goto sendit;
        }
-#ifndef notdef
        /*
         * If source address not specified yet, use address
         * of outgoing interface.
         */
        if (ip->ip_src.s_addr == INADDR_ANY) {
+               IFA_LOCK_SPIN(&ia->ia_ifa);
                ip->ip_src = IA_SIN(ia)->sin_addr;
+               IFA_UNLOCK(&ia->ia_ifa);
 #if IPFIREWALL_FORWARD
-               /* Keep note that we did this - if the firewall changes
+               /*
+                * Keep note that we did this - if the firewall changes
                 * the next-hop, our interface may change, changing the
                 * default source IP. It's a shame so much effort happens
-                * twice. Oh well. 
+                * twice. Oh well.
                 */
-               fwd_rewrite_src++;
+               ipobf.fwd_rewrite_src = TRUE;
 #endif /* IPFIREWALL_FORWARD */
        }
-#endif /* notdef */
 
        /*
         * Look for broadcast address and
         * and verify user is allowed to send
         * such a packet.
         */
-       if (isbroadcast) {
-               if ((ifp->if_flags & IFF_BROADCAST) == 0) {
+       if (ipobf.isbroadcast) {
+               if (!(ifp->if_flags & IFF_BROADCAST)) {
                        error = EADDRNOTAVAIL;
                        goto bad;
                }
-               if ((flags & IP_ALLOWBROADCAST) == 0) {
+               if (!(flags & IP_ALLOWBROADCAST)) {
                        error = EACCES;
                        goto bad;
                }
@@ -601,78 +1100,198 @@ loopit:
        }
 
 sendit:
-        /*
-         * Force IP TTL to 255 following draft-ietf-zeroconf-ipv4-linklocal.txt
-         */
-        if (IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) || IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) {
+#if PF
+       /* Invoke outbound packet filter */
+       if (PF_IS_ENABLED) {
+               int rc;
+
+               m0 = m; /* Save for later */
+#if DUMMYNET
+               args.fwa_m = m;
+               args.fwa_next_hop = dst;
+               args.fwa_oif = ifp;
+               args.fwa_ro = ro;
+               args.fwa_dst = dst;
+               args.fwa_oflags = flags;
+               if (flags & IP_OUTARGS)
+                       args.fwa_ipoa = ipoa;
+               rc = pf_af_hook(ifp, mppn, &m, AF_INET, FALSE, &args);
+#else /* DUMMYNET */
+               rc = pf_af_hook(ifp, mppn, &m, AF_INET, FALSE, NULL);
+#endif /* DUMMYNET */
+               if (rc != 0 || m == NULL) {
+                       /* Move to the next packet */
+                       m = *mppn;
+
+                       /* Skip ahead if first packet in list got dropped */
+                       if (packetlist == m0)
+                               packetlist = m;
+
+                       if (m != NULL) {
+                               m0 = m;
+                               /* Next packet in the chain */
+                               goto loopit;
+                       } else if (packetlist != NULL) {
+                               /* No more packet; send down the chain */
+                               goto sendchain;
+                       }
+                       /* Nothing left; we're done */
+                       goto done;
+               }
+               m0 = m;
+               ip = mtod(m, struct ip *);
+               pkt_dst = ip->ip_dst;
+               hlen = IP_VHL_HL(ip->ip_vhl) << 2;
+       }
+#endif /* PF */
+       /*
+        * Force IP TTL to 255 following draft-ietf-zeroconf-ipv4-linklocal.txt
+        */
+       if (IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) ||
+           IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) {
                ip_linklocal_stat.iplls_out_total++;
                if (ip->ip_ttl != MAXTTL) {
                        ip_linklocal_stat.iplls_out_badttl++;
-                       ip->ip_ttl = MAXTTL;
+                       ip->ip_ttl = MAXTTL;
                }
-        }
+       }
 
-injectit:
-       if (!didfilter && !TAILQ_EMPTY(&ipv4_filters)) {
+       if (!ipobf.didfilter && !TAILQ_EMPTY(&ipv4_filters)) {
                struct ipfilter *filter;
-               int seen = (inject_filter_ref == 0);
-               
-               lck_mtx_unlock(ip_mutex);
+               int seen = (inject_filter_ref == NULL);
+               ipf_pktopts.ippo_flags &= ~IPPOF_MCAST_OPTS;
+
+               /*
+                * Check that a TSO frame isn't passed to a filter.
+                * This could happen if a filter is inserted while
+                * TCP is sending the TSO packet.
+                */
+               if (m->m_pkthdr.csum_flags & CSUM_TSO_IPV4) {
+                       error = EMSGSIZE;
+                       goto bad;
+               }
+
                ipf_ref();
-               
+
                /* 4135317 - always pass network byte order to filter */
+#if BYTE_ORDER != BIG_ENDIAN
                HTONS(ip->ip_len);
                HTONS(ip->ip_off);
-               
+#endif
                TAILQ_FOREACH(filter, &ipv4_filters, ipf_link) {
                        if (seen == 0) {
-                               if ((struct ipfilter *)inject_filter_ref == filter)
+                               if ((struct ipfilter *)inject_filter_ref ==
+                                   filter)
                                        seen = 1;
                        } else if (filter->ipf_filter.ipf_output) {
                                errno_t result;
-                               result = filter->ipf_filter.ipf_output(filter->ipf_filter.cookie, (mbuf_t*)&m, 0);
+                               result = filter->ipf_filter.
+                                   ipf_output(filter->ipf_filter.cookie,
+                                   (mbuf_t *)&m, ippo);
                                if (result == EJUSTRETURN) {
                                        ipf_unref();
                                        goto done;
                                }
                                if (result != 0) {
                                        ipf_unref();
-                                       lck_mtx_lock(ip_mutex);
                                        goto bad;
                                }
                        }
                }
-               
                /* set back to host byte order */
                ip = mtod(m, struct ip *);
+#if BYTE_ORDER != BIG_ENDIAN
                NTOHS(ip->ip_len);
                NTOHS(ip->ip_off);
-               
+#endif
                ipf_unref();
-               lck_mtx_lock(ip_mutex);
        }
 
-#if IPSEC
-       /* temporary for testing only: bypass ipsec alltogether */
+#if NECP
+       /* Process Network Extension Policy. Will Pass, Drop, or Rebind packet. */
+       necp_matched_policy_id = necp_ip_output_find_policy_match (m,
+               flags, (flags & IP_OUTARGS) ? ipoa : NULL, &necp_result, &necp_result_parameter);
+       if (necp_matched_policy_id) {
+               necp_mark_packet_from_ip(m, necp_matched_policy_id);
+               switch (necp_result) {
+                       case NECP_KERNEL_POLICY_RESULT_PASS:
+                               /* Check if the interface is allowed */
+                               if (!necp_packet_is_allowed_over_interface(m, ifp)) {
+                                       error = EHOSTUNREACH;
+                                       OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+                                       goto bad;
+                               }
+                               goto skip_ipsec;
+                       case NECP_KERNEL_POLICY_RESULT_DROP:
+                       case NECP_KERNEL_POLICY_RESULT_SOCKET_DIVERT:
+                               /* Flow divert packets should be blocked at the IP layer */
+                               error = EHOSTUNREACH;
+                               OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+                               goto bad;
+                       case NECP_KERNEL_POLICY_RESULT_IP_TUNNEL: {
+                               /* Verify that the packet is being routed to the tunnel */
+                               struct ifnet *policy_ifp = necp_get_ifnet_from_result_parameter(&necp_result_parameter);
+                               if (policy_ifp == ifp) {
+                                       /* Check if the interface is allowed */
+                                       if (!necp_packet_is_allowed_over_interface(m, ifp)) {
+                                               error = EHOSTUNREACH;
+                                               OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+                                               goto bad;
+                                       }
+                                       goto skip_ipsec;
+                               } else {
+                                       if (necp_packet_can_rebind_to_ifnet(m, policy_ifp, &necp_route, AF_INET)) {
+                                               /* Check if the interface is allowed */
+                                               if (!necp_packet_is_allowed_over_interface(m, policy_ifp)) {
+                                                       error = EHOSTUNREACH;
+                                                       OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+                                                       goto bad;
+                                               }
 
-       if (ipsec_bypass != 0 || (flags & IP_NOIPSEC) != 0)
-               goto skip_ipsec;
-
-       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_START, 0,0,0,0,0);
+                                               /* Set ifp to the tunnel interface, since it is compatible with the packet */
+                                               ifp = policy_ifp;
+                                               ro = &necp_route;
+                                               goto skip_ipsec;
+                                       } else {
+                                               error = ENETUNREACH;
+                                               OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+                                               goto bad;
+                                       }
+                               }
+                       }
+                       default:
+                               break;
+               }
+       }
+       /* Catch-all to check if the interface is allowed */
+       if (!necp_packet_is_allowed_over_interface(m, ifp)) {
+               error = EHOSTUNREACH;
+               OSAddAtomic(1, &ipstat.ips_necp_policy_drop);
+               goto bad;
+       }
+#endif /* NECP */
 
-       lck_mtx_lock(sadb_mutex);
+#if IPSEC
+       if (ipsec_bypass != 0 || (flags & IP_NOIPSEC))
+               goto skip_ipsec;
 
-       /* get SP for this packet */
-       if (so == NULL)
-               sp = ipsec4_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, flags, &error);
-       else
-               sp = ipsec4_getpolicybysock(m, IPSEC_DIR_OUTBOUND, so, &error);
+       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_START, 0, 0, 0, 0, 0);
 
        if (sp == NULL) {
-               ipsecstat.out_inval++;
-               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 0,0,0,0,0);
-               lck_mtx_unlock(sadb_mutex);
-               goto bad;
+               /* get SP for this packet */
+               if (so != NULL) {
+                       sp = ipsec4_getpolicybysock(m, IPSEC_DIR_OUTBOUND,
+                               so, &error);
+               } else {
+                       sp = ipsec4_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
+                               flags, &error);
+               }
+               if (sp == NULL) {
+                       IPSEC_STAT_INCREMENT(ipsecstat.out_inval);
+                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                                                0, 0, 0, 0, 0);
+                       goto bad;
+               }
        }
 
        error = 0;
@@ -680,27 +1299,35 @@ injectit:
        /* check policy */
        switch (sp->policy) {
        case IPSEC_POLICY_DISCARD:
+       case IPSEC_POLICY_GENERATE:
                /*
                 * This packet is just discarded.
                 */
-               ipsecstat.out_polvio++;
-               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 1,0,0,0,0);
-               lck_mtx_unlock(sadb_mutex);
+               IPSEC_STAT_INCREMENT(ipsecstat.out_polvio);
+               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                   1, 0, 0, 0, 0);
                goto bad;
 
        case IPSEC_POLICY_BYPASS:
        case IPSEC_POLICY_NONE:
                /* no need to do IPsec. */
-               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 2,0,0,0,0);
-               lck_mtx_unlock(sadb_mutex);
+               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                   2, 0, 0, 0, 0);
                goto skip_ipsec;
-       
+
        case IPSEC_POLICY_IPSEC:
                if (sp->req == NULL) {
                        /* acquire a policy */
                        error = key_spdacquire(sp);
-                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 3,0,0,0,0);
-                       lck_mtx_unlock(sadb_mutex);
+                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                           3, 0, 0, 0, 0);
+                       goto bad;
+               }
+               if (sp->ipsec_if) {
+                       /* Verify the redirect to ipsec interface */
+                       if (sp->ipsec_if == ifp) {
+                               goto skip_ipsec;
+                       }
                        goto bad;
                }
                break;
@@ -709,16 +1336,14 @@ injectit:
        default:
                printf("ip_output: Invalid policy found. %d\n", sp->policy);
        }
-    {
-       struct ipsec_output_state state;
-       bzero(&state, sizeof(state));
-       state.m = m;
+       {
+       ipsec_state.m = m;
        if (flags & IP_ROUTETOIF) {
-               state.ro = &iproute;
-               bzero(&iproute, sizeof(iproute));
-       } else
-               state.ro = ro;
-       state.dst = (struct sockaddr *)dst;
+               bzero(&ipsec_state.ro, sizeof (ipsec_state.ro));
+       } else {
+               route_copyout((struct route *)&ipsec_state.ro, ro, sizeof (struct route));
+       }
+       ipsec_state.dst = SA(dst);
 
        ip->ip_sum = 0;
 
@@ -726,34 +1351,50 @@ injectit:
         * XXX
         * delayed checksums are not currently compatible with IPsec
         */
-       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
+       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
                in_delayed_cksum(m);
-               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
-       }
 
+#if BYTE_ORDER != BIG_ENDIAN
        HTONS(ip->ip_len);
        HTONS(ip->ip_off);
+#endif
+
+       DTRACE_IP6(send, struct mbuf *, m, struct inpcb *, NULL,
+           struct ip *, ip, struct ifnet *, ifp,
+           struct ip *, ip, struct ip6_hdr *, NULL);
+
+       error = ipsec4_output(&ipsec_state, sp, flags);
+       if (ipsec_state.tunneled == 6) {
+               m0 = m = NULL;
+               error = 0;
+               goto bad;
+       }
+
+       m0 = m = ipsec_state.m;
+
+#if DUMMYNET
+       /*
+        * If we're about to use the route in ipsec_state
+        * and this came from dummynet, cleaup now.
+        */
+       if (ro == &saved_route &&
+           (!(flags & IP_ROUTETOIF) || ipsec_state.tunneled))
+               ROUTE_RELEASE(ro);
+#endif /* DUMMYNET */
 
-       lck_mtx_unlock(ip_mutex);
-       error = ipsec4_output(&state, sp, flags);
-       lck_mtx_unlock(sadb_mutex);
-       lck_mtx_lock(ip_mutex);
-    
-       m0 = m = state.m;
-       
        if (flags & IP_ROUTETOIF) {
                /*
                 * if we have tunnel mode SA, we may need to ignore
                 * IP_ROUTETOIF.
                 */
-               if (state.ro != &iproute || state.ro->ro_rt != NULL) {
+               if (ipsec_state.tunneled) {
                        flags &= ~IP_ROUTETOIF;
-                       ro = state.ro;
+                       ro = (struct route *)&ipsec_state.ro;
                }
-       } else
-               ro = state.ro;
-
-       dst = (struct sockaddr_in *)state.dst;
+       } else {
+               ro = (struct route *)&ipsec_state.ro;
+       }
+       dst = SIN(ipsec_state.dst);
        if (error) {
                /* mbuf is already reclaimed in ipsec4_output. */
                m0 = NULL;
@@ -766,199 +1407,213 @@ injectit:
                        break;
                default:
                        printf("ip4_output (ipsec): error code %d\n", error);
-                       /*fall through*/
+                       /* FALLTHRU */
                case ENOENT:
                        /* don't show these error codes to the user */
                        error = 0;
                        break;
                }
-               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 4,0,0,0,0);
+               KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                   4, 0, 0, 0, 0);
                goto bad;
        }
-    }
+       }
 
        /* be sure to update variables that are affected by ipsec4_output() */
        ip = mtod(m, struct ip *);
-       
+
 #ifdef _IP_VHL
        hlen = IP_VHL_HL(ip->ip_vhl) << 2;
-#else
+#else /* !_IP_VHL */
        hlen = ip->ip_hl << 2;
-#endif
+#endif /* !_IP_VHL */
        /* Check that there wasn't a route change and src is still valid */
-
-       if (ro->ro_rt && ro->ro_rt->generation_id != route_generation) {
-               if (ifa_foraddr(ip->ip_src.s_addr) == 0 && ((flags & (IP_ROUTETOIF | IP_FORWARDING)) == 0)) {
-                       error = EADDRNOTAVAIL;
-                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 5,0,0,0,0);
+       if (ROUTE_UNUSABLE(ro)) {
+               ROUTE_RELEASE(ro);
+               VERIFY(src_ia == NULL);
+               if (ip->ip_src.s_addr != INADDR_ANY &&
+                   !(flags & (IP_ROUTETOIF | IP_FORWARDING)) &&
+                   (src_ia = ifa_foraddr(ip->ip_src.s_addr)) == NULL) {
+                       error = EADDRNOTAVAIL;
+                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                           5, 0, 0, 0, 0);
                        goto bad;
                }
-               rtfree(ro->ro_rt);
-               ro->ro_rt = NULL;
+               if (src_ia != NULL) {
+                       IFA_REMREF(&src_ia->ia_ifa);
+                       src_ia = NULL;
+               }
        }
 
        if (ro->ro_rt == NULL) {
-               if ((flags & IP_ROUTETOIF) == 0) {
-                       printf("ip_output: "
-                               "can't update route after IPsec processing\n");
-                       error = EHOSTUNREACH;   /*XXX*/ 
-                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 6,0,0,0,0);
+               if (!(flags & IP_ROUTETOIF)) {
+                       printf("%s: can't update route after "
+                           "IPsec processing\n", __func__);
+                       error = EHOSTUNREACH;   /* XXX */
+                       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+                           6, 0, 0, 0, 0);
                        goto bad;
                }
        } else {
-               if (ia)
-                       ifafree(&ia->ia_ifa);
+               if (ia != NULL)
+                       IFA_REMREF(&ia->ia_ifa);
+               RT_LOCK_SPIN(ro->ro_rt);
                ia = ifatoia(ro->ro_rt->rt_ifa);
-               if (ia)
-                       ifaref(&ia->ia_ifa);
+               if (ia != NULL) {
+                       /* Become a regular mutex */
+                       RT_CONVERT_LOCK(ro->ro_rt);
+                       IFA_ADDREF(&ia->ia_ifa);
+               }
                ifp = ro->ro_rt->rt_ifp;
+               RT_UNLOCK(ro->ro_rt);
        }
 
        /* make it flipped, again. */
+#if BYTE_ORDER != BIG_ENDIAN
        NTOHS(ip->ip_len);
        NTOHS(ip->ip_off);
-       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END, 7,0xff,0xff,0xff,0xff);
-       
+#endif
+       KERNEL_DEBUG(DBG_FNC_IPSEC4_OUTPUT | DBG_FUNC_END,
+           7, 0xff, 0xff, 0xff, 0xff);
+
        /* Pass to filters again */
        if (!TAILQ_EMPTY(&ipv4_filters)) {
                struct ipfilter *filter;
-               
-               lck_mtx_unlock(ip_mutex);
+
+               ipf_pktopts.ippo_flags &= ~IPPOF_MCAST_OPTS;
+
+               /*
+                * Check that a TSO frame isn't passed to a filter.
+                * This could happen if a filter is inserted while
+                * TCP is sending the TSO packet.
+                */
+               if (m->m_pkthdr.csum_flags & CSUM_TSO_IPV4) {
+                       error = EMSGSIZE;
+                       goto bad;
+               }
+
                ipf_ref();
-               
+
                /* 4135317 - always pass network byte order to filter */
+#if BYTE_ORDER != BIG_ENDIAN
                HTONS(ip->ip_len);
                HTONS(ip->ip_off);
-               
+#endif
                TAILQ_FOREACH(filter, &ipv4_filters, ipf_link) {
                        if (filter->ipf_filter.ipf_output) {
                                errno_t result;
-                               result = filter->ipf_filter.ipf_output(filter->ipf_filter.cookie, (mbuf_t*)&m, 0);
+                               result = filter->ipf_filter.
+                                   ipf_output(filter->ipf_filter.cookie,
+                                   (mbuf_t *)&m, ippo);
                                if (result == EJUSTRETURN) {
                                        ipf_unref();
                                        goto done;
                                }
                                if (result != 0) {
                                        ipf_unref();
-                                       lck_mtx_lock(ip_mutex);
                                        goto bad;
                                }
                        }
                }
-               
                /* set back to host byte order */
                ip = mtod(m, struct ip *);
+#if BYTE_ORDER != BIG_ENDIAN
                NTOHS(ip->ip_len);
                NTOHS(ip->ip_off);
-               
+#endif
                ipf_unref();
-               lck_mtx_lock(ip_mutex);
        }
 skip_ipsec:
-#endif /*IPSEC*/
-
-       /*
-        * IpHack's section.
-        * - Xlate: translate packet's addr/port (NAT).
-        * - Firewall: deny/allow/etc.
-        * - Wrap: fake packet's addr/port <unimpl.>
-        * - Encapsulate: put it in another IP and send out. <unimp.>
-        */ 
-       if (fr_checkp) {
-               struct  mbuf    *m1 = m;
-
-               if ((error = (*fr_checkp)(ip, hlen, ifp, 1, &m1)) || !m1) {
-                       lck_mtx_unlock(ip_mutex);
-                       goto done;
-               }
-               ip = mtod(m0 = m = m1, struct ip *);
-       }
+#endif /* IPSEC */
 
+#if IPFIREWALL
        /*
         * Check with the firewall...
         * but not if we are already being fwd'd from a firewall.
         */
-       if (fw_enable && IPFW_LOADED && !args.next_hop) {
+       if (fw_enable && IPFW_LOADED && !args.fwa_next_hop) {
                struct sockaddr_in *old = dst;
 
-               args.m = m;
-               args.next_hop = dst;
-               args.oif = ifp;
-               lck_mtx_unlock(ip_mutex);
-               off = ip_fw_chk_ptr(&args);
-               m = args.m;
-               dst = args.next_hop;
-
-                /*
-                 * On return we must do the following:
-                 * IP_FW_PORT_DENY_FLAG                -> drop the pkt (XXX new)
-                 * 1<=off<= 0xffff   -> DIVERT
-                 * (off & IP_FW_PORT_DYNT_FLAG)        -> send to a DUMMYNET pipe
-                 * (off & IP_FW_PORT_TEE_FLAG) -> TEE the packet
-                 * dst != old        -> IPFIREWALL_FORWARD
-                 * off==0, dst==old  -> accept
-                 * If some of the above modules is not compiled in, then
-                 * we should't have to check the corresponding condition
-                 * (because the ipfw control socket should not accept
-                 * unsupported rules), but better play safe and drop
-                 * packets in case of doubt.
-                 */
+               args.fwa_m = m;
+               args.fwa_next_hop = dst;
+               args.fwa_oif = ifp;
+               ipfwoff = ip_fw_chk_ptr(&args);
+               m = args.fwa_m;
+               dst = args.fwa_next_hop;
+
+               /*
+                * On return we must do the following:
+                *   IP_FW_PORT_DENY_FLAG         -> drop the pkt (XXX new)
+                *   1<=off<= 0xffff              -> DIVERT
+                *   (off & IP_FW_PORT_DYNT_FLAG) -> send to a DUMMYNET pipe
+                *   (off & IP_FW_PORT_TEE_FLAG)  -> TEE the packet
+                *   dst != old                   -> IPFIREWALL_FORWARD
+                *   off==0, dst==old             -> accept
+                * If some of the above modules is not compiled in, then
+                * we should't have to check the corresponding condition
+                * (because the ipfw control socket should not accept
+                * unsupported rules), but better play safe and drop
+                * packets in case of doubt.
+                */
                m0 = m;
-               if ( (off & IP_FW_PORT_DENY_FLAG) || m == NULL) {
+               if ((ipfwoff & IP_FW_PORT_DENY_FLAG) || m == NULL) {
                        if (m)
                                m_freem(m);
-                       error = EACCES ;
-                       goto done ;
+                       error = EACCES;
+                       goto done;
                }
                ip = mtod(m, struct ip *);
-               if (off == 0 && dst == old) {/* common case */
-                       lck_mtx_lock(ip_mutex);
-                       goto pass ;
+
+               if (ipfwoff == 0 && dst == old) {       /* common case */
+                       goto pass;
                }
 #if DUMMYNET
-                if (DUMMYNET_LOADED && (off & IP_FW_PORT_DYNT_FLAG) != 0) {
-                    /*
-                     * pass the pkt to dummynet. Need to include
-                     * pipe number, m, ifp, ro, dst because these are
-                     * not recomputed in the next pass.
-                     * All other parameters have been already used and
-                     * so they are not needed anymore. 
-                     * XXX note: if the ifp or ro entry are deleted
-                     * while a pkt is in dummynet, we are in trouble!
-                     */ 
-                   args.ro = ro;
-                   args.dst = dst;
-                   args.flags = flags;
-
-                   error = ip_dn_io_ptr(m, off & 0xffff, DN_TO_IP_OUT,
-                               &args);
-                   goto done;
+               if (DUMMYNET_LOADED && (ipfwoff & IP_FW_PORT_DYNT_FLAG) != 0) {
+                       /*
+                        * pass the pkt to dummynet. Need to include
+                        * pipe number, m, ifp, ro, dst because these are
+                        * not recomputed in the next pass.
+                        * All other parameters have been already used and
+                        * so they are not needed anymore.
+                        * XXX note: if the ifp or ro entry are deleted
+                        * while a pkt is in dummynet, we are in trouble!
+                        */
+                       args.fwa_ro = ro;
+                       args.fwa_dst = dst;
+                       args.fwa_oflags = flags;
+                       if (flags & IP_OUTARGS)
+                               args.fwa_ipoa = ipoa;
+
+                       error = ip_dn_io_ptr(m, ipfwoff & 0xffff, DN_TO_IP_OUT,
+                           &args, DN_CLIENT_IPFW);
+                       goto done;
                }
 #endif /* DUMMYNET */
-               lck_mtx_lock(ip_mutex);
 #if IPDIVERT
-               if (off != 0 && (off & IP_FW_PORT_DYNT_FLAG) == 0) {
+               if (ipfwoff != 0 && (ipfwoff & IP_FW_PORT_DYNT_FLAG) == 0) {
                        struct mbuf *clone = NULL;
 
                        /* Clone packet if we're doing a 'tee' */
-                       if ((off & IP_FW_PORT_TEE_FLAG) != 0)
+                       if ((ipfwoff & IP_FW_PORT_TEE_FLAG) != 0)
                                clone = m_dup(m, M_DONTWAIT);
                        /*
                         * XXX
                         * delayed checksums are not currently compatible
                         * with divert sockets.
                         */
-                       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
+                       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
                                in_delayed_cksum(m);
-                               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
-                       }
 
                        /* Restore packet header fields to original values */
+
+#if BYTE_ORDER != BIG_ENDIAN
                        HTONS(ip->ip_len);
                        HTONS(ip->ip_off);
+#endif
 
                        /* Deliver packet to divert input routine */
-                       divert_packet(m, 0, off & 0xffff, args.divert_rule);
+                       divert_packet(m, 0, ipfwoff & 0xffff,
+                           args.fwa_divert_rule);
 
                        /* If 'tee', continue with original packet */
                        if (clone != NULL) {
@@ -966,14 +1621,13 @@ skip_ipsec:
                                ip = mtod(m, struct ip *);
                                goto pass;
                        }
-                       lck_mtx_unlock(ip_mutex);
                        goto done;
                }
-#endif
-
+#endif /* IPDIVERT */
 #if IPFIREWALL_FORWARD
-               /* Here we check dst to make sure it's directly reachable on the
-                * interface we previously thought it was.
+               /*
+                * Here we check dst to make sure it's directly reachable on
+                * the interface we previously thought it was.
                 * If it isn't (which may be likely in some situations) we have
                 * to re-route it (ie, find a route for the next-hop and the
                 * associated interface) and set them here. This is nested
@@ -981,240 +1635,264 @@ skip_ipsec:
                 * such control is nigh impossible. So we do it here.
                 * And I'm babbling.
                 */
-               if (off == 0 && old != dst) {
+               if (ipfwoff == 0 && old != dst) {
                        struct in_ifaddr *ia_fw;
+                       struct route *ro_fwd = &sro_fwd;
 
-                       /* It's changed... */
-                       /* There must be a better way to do this next line... */
-                       static struct route sro_fwd, *ro_fwd = &sro_fwd;
 #if IPFIREWALL_FORWARD_DEBUG
                        printf("IPFIREWALL_FORWARD: New dst ip: ");
                        print_ip(dst->sin_addr);
                        printf("\n");
-#endif
+#endif /* IPFIREWALL_FORWARD_DEBUG */
                        /*
                         * We need to figure out if we have been forwarded
-                        * to a local socket. If so then we should somehow 
+                        * to a local socket. If so then we should somehow
                         * "loop back" to ip_input, and get directed to the
                         * PCB as if we had received this packet. This is
                         * because it may be dificult to identify the packets
                         * you want to forward until they are being output
                         * and have selected an interface. (e.g. locally
                         * initiated packets) If we used the loopback inteface,
-                        * we would not be able to control what happens 
+                        * we would not be able to control what happens
                         * as the packet runs through ip_input() as
                         * it is done through a ISR.
                         */
+                       lck_rw_lock_shared(in_ifaddr_rwlock);
                        TAILQ_FOREACH(ia_fw, &in_ifaddrhead, ia_link) {
                                /*
                                 * If the addr to forward to is one
                                 * of ours, we pretend to
                                 * be the destination for this packet.
                                 */
+                               IFA_LOCK_SPIN(&ia_fw->ia_ifa);
                                if (IA_SIN(ia_fw)->sin_addr.s_addr ==
-                                                dst->sin_addr.s_addr)
+                                   dst->sin_addr.s_addr) {
+                                       IFA_UNLOCK(&ia_fw->ia_ifa);
                                        break;
+                               }
+                               IFA_UNLOCK(&ia_fw->ia_ifa);
                        }
-                       if (ia) {
+                       lck_rw_done(in_ifaddr_rwlock);
+                       if (ia_fw) {
                                /* tell ip_input "dont filter" */
-                               struct m_tag            *fwd_tag;
+                               struct m_tag            *fwd_tag;
                                struct ip_fwd_tag       *ipfwd_tag;
-                               
-                               fwd_tag = m_tag_alloc(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_IPFORWARD,
-                                               sizeof(struct sockaddr_in), M_NOWAIT);
+
+                               fwd_tag = m_tag_create(KERNEL_MODULE_TAG_ID,
+                                   KERNEL_TAG_TYPE_IPFORWARD,
+                                   sizeof (*ipfwd_tag), M_NOWAIT, m);
                                if (fwd_tag == NULL) {
                                        error = ENOBUFS;
                                        goto bad;
                                }
-                               
+
                                ipfwd_tag = (struct ip_fwd_tag *)(fwd_tag+1);
-                               ipfwd_tag->next_hop = args.next_hop;
+                               ipfwd_tag->next_hop = args.fwa_next_hop;
 
                                m_tag_prepend(m, fwd_tag);
 
                                if (m->m_pkthdr.rcvif == NULL)
-                                       m->m_pkthdr.rcvif = ifunit("lo0");
-                               if ((~IF_HWASSIST_CSUM_FLAGS(m->m_pkthdr.rcvif->if_hwassist) & 
-                                               m->m_pkthdr.csum_flags) == 0) {
-                                       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-                                               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
-                                               m->m_pkthdr.csum_flags |=
-                                                       CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
-                                               m->m_pkthdr.csum_data = 0xffff;
-                                       }
-                                       m->m_pkthdr.csum_flags |=
-                                               CSUM_IP_CHECKED | CSUM_IP_VALID;
-                               }
-                               else if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-                                       in_delayed_cksum(m);
-                                       m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
-                                       ip->ip_sum = in_cksum(m, hlen);
-                               }
+                                       m->m_pkthdr.rcvif = lo_ifp;
+
+#if BYTE_ORDER != BIG_ENDIAN
                                HTONS(ip->ip_len);
                                HTONS(ip->ip_off);
-                               
-                               lck_mtx_unlock(ip_mutex);
-                               
-                               /*  we need to call dlil_output to run filters
-                                *      and resync to avoid recursion loops.
+#endif
+                               mbuf_outbound_finalize(m, PF_INET, 0);
+
+                               /*
+                                * we need to call dlil_output to run filters
+                                * and resync to avoid recursion loops.
                                 */
                                if (lo_ifp) {
-                                       dlil_output(lo_ifp, PF_INET, m, 0, (struct sockaddr *)dst, 0);
-                               }
-                               else {
-                                       printf("ip_output: no loopback ifp for forwarding!!!\n");
+                                       dlil_output(lo_ifp, PF_INET, m, NULL,
+                                           SA(dst), 0, adv);
+                               } else {
+                                       printf("%s: no loopback ifp for "
+                                           "forwarding!!!\n", __func__);
                                }
                                goto done;
                        }
-                       /* Some of the logic for this was
-                        * nicked from above.
+                       /*
+                        * Some of the logic for this was nicked from above.
                         *
                         * This rewrites the cached route in a local PCB.
                         * Is this what we want to do?
                         */
-                       bcopy(dst, &ro_fwd->ro_dst, sizeof(*dst));
+                       ROUTE_RELEASE(ro_fwd);
+                       bcopy(dst, &ro_fwd->ro_dst, sizeof (*dst));
 
-                       ro_fwd->ro_rt = 0;
-                       rtalloc_ign(ro_fwd, RTF_PRCLONING);
+                       rtalloc_ign(ro_fwd, RTF_PRCLONING, false);
 
-                       if (ro_fwd->ro_rt == 0) {
-                               ipstat.ips_noroute++;
+                       if (ro_fwd->ro_rt == NULL) {
+                               OSAddAtomic(1, &ipstat.ips_noroute);
                                error = EHOSTUNREACH;
                                goto bad;
                        }
 
+                       RT_LOCK_SPIN(ro_fwd->ro_rt);
                        ia_fw = ifatoia(ro_fwd->ro_rt->rt_ifa);
+                       if (ia_fw != NULL) {
+                               /* Become a regular mutex */
+                               RT_CONVERT_LOCK(ro_fwd->ro_rt);
+                               IFA_ADDREF(&ia_fw->ia_ifa);
+                       }
                        ifp = ro_fwd->ro_rt->rt_ifp;
                        ro_fwd->ro_rt->rt_use++;
                        if (ro_fwd->ro_rt->rt_flags & RTF_GATEWAY)
-                               dst = (struct sockaddr_in *)ro_fwd->ro_rt->rt_gateway;
-                       if (ro_fwd->ro_rt->rt_flags & RTF_HOST)
-                               isbroadcast =
-                                   (ro_fwd->ro_rt->rt_flags & RTF_BROADCAST);
-                       else
-                               isbroadcast = in_broadcast(dst->sin_addr, ifp);
-                       rtfree(ro->ro_rt);
+                               dst = SIN(ro_fwd->ro_rt->rt_gateway);
+                       if (ro_fwd->ro_rt->rt_flags & RTF_HOST) {
+                               /* double negation needed for bool bit field */
+                               ipobf.isbroadcast =
+                                   !!(ro_fwd->ro_rt->rt_flags & RTF_BROADCAST);
+                       } else {
+                               /* Become a regular mutex */
+                               RT_CONVERT_LOCK(ro_fwd->ro_rt);
+                               ipobf.isbroadcast =
+                                   in_broadcast(dst->sin_addr, ifp);
+                       }
+                       RT_UNLOCK(ro_fwd->ro_rt);
+                       ROUTE_RELEASE(ro);
                        ro->ro_rt = ro_fwd->ro_rt;
-                       dst = (struct sockaddr_in *)&ro_fwd->ro_dst;
+                       ro_fwd->ro_rt = NULL;
+                       dst = SIN(&ro_fwd->ro_dst);
 
                        /*
                         * If we added a default src ip earlier,
                         * which would have been gotten from the-then
                         * interface, do it again, from the new one.
                         */
-                       if (fwd_rewrite_src)
-                               ip->ip_src = IA_SIN(ia_fw)->sin_addr;
-                       goto pass ;
+                       if (ia_fw != NULL) {
+                               if (ipobf.fwd_rewrite_src) {
+                                       IFA_LOCK_SPIN(&ia_fw->ia_ifa);
+                                       ip->ip_src = IA_SIN(ia_fw)->sin_addr;
+                                       IFA_UNLOCK(&ia_fw->ia_ifa);
+                               }
+                               IFA_REMREF(&ia_fw->ia_ifa);
+                       }
+                       goto pass;
                }
 #endif /* IPFIREWALL_FORWARD */
-                /*
-                 * if we get here, none of the above matches, and 
-                 * we have to drop the pkt
-                 */
+               /*
+                * if we get here, none of the above matches, and
+                * we have to drop the pkt
+                */
                m_freem(m);
                error = EACCES; /* not sure this is the right error msg */
-               lck_mtx_unlock(ip_mutex);
                goto done;
        }
 
 pass:
-#if __APPLE__
-       /* Do not allow loopback address to wind up on a wire */
-       if ((ifp->if_flags & IFF_LOOPBACK) == 0 &&
-                ((ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
-                 (ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET)) {
-               ipstat.ips_badaddr++;
-               m_freem(m);
-               /* 
-                * Do not simply drop the packet just like a firewall -- we want the 
-                * the application to feel the pain.
-                * Return ENETUNREACH like ip6_output does in some similar cases. 
-                * This can startle the otherwise clueless process that specifies
-                * loopback as the source address.
-                */
-               error = ENETUNREACH;
-               lck_mtx_unlock(ip_mutex);
-               goto done;
+#endif /* IPFIREWALL */
+
+       /* 127/8 must not appear on wire - RFC1122 */
+       if (!(ifp->if_flags & IFF_LOOPBACK) &&
+           ((ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
+           (ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET)) {
+               OSAddAtomic(1, &ipstat.ips_badaddr);
+               error = EADDRNOTAVAIL;
+               goto bad;
        }
-#endif
-       m->m_pkthdr.csum_flags |= CSUM_IP;
-       sw_csum = m->m_pkthdr.csum_flags 
-               & ~IF_HWASSIST_CSUM_FLAGS(ifp->if_hwassist);
 
-       if ((ifp->if_hwassist & CSUM_TCP_SUM16) != 0) {
-               /*
-                * Special case code for GMACE
-                * frames that can be checksumed by GMACE SUM16 HW:
-                * frame >64, no fragments, no UDP
-                */
-               if (apple_hwcksum_tx && (m->m_pkthdr.csum_flags & CSUM_TCP)
-                       && (ip->ip_len > 50) && (ip->ip_len <= ifp->if_mtu)) {
-                       /* Apple GMAC HW, expects STUFF_OFFSET << 16  | START_OFFSET */
-                       u_short offset = (IP_VHL_HL(ip->ip_vhl) << 2) +14 ; /* IP+Enet header length */
-                       u_short csumprev= m->m_pkthdr.csum_data & 0xFFFF;
-                       m->m_pkthdr.csum_flags = CSUM_DATA_VALID | CSUM_TCP_SUM16; /* for GMAC */
-                       m->m_pkthdr.csum_data = (csumprev + offset)  << 16 ;
-                       m->m_pkthdr.csum_data += offset; 
-                       sw_csum = CSUM_DELAY_IP; /* do IP hdr chksum in software */
-               }
-               else {
-                       /* let the software handle any UDP or TCP checksums */
-                       sw_csum |= (CSUM_DELAY_DATA & m->m_pkthdr.csum_flags);
+       if (ipoa != NULL) {
+               u_int8_t dscp = ip->ip_tos >> IPTOS_DSCP_SHIFT;
+
+               error = set_packet_qos(m, ifp,
+                   ipoa->ipoa_flags & IPOAF_QOSMARKING_ALLOWED ? TRUE : FALSE,
+                   ipoa->ipoa_sotc, ipoa->ipoa_netsvctype, &dscp);
+               if (error == 0) {
+                       ip->ip_tos &= IPTOS_ECN_MASK;
+                       ip->ip_tos |= dscp << IPTOS_DSCP_SHIFT;
+               } else {
+                       printf("%s if_dscp_for_mbuf() error %d\n", __func__, error);
+                       error = 0;
                }
        }
-       
-       if (sw_csum & CSUM_DELAY_DATA) {
-               in_delayed_cksum(m);
-               sw_csum &= ~CSUM_DELAY_DATA;
-               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
+
+       /*
+        * Some Wi-Fi AP implementations do not correctly handle multicast IP
+        * packets with DSCP bits set -- see radr://9331522 -- so as a
+        * workaround we clear the DSCP bits and set the service class to BE
+        */
+       if (IN_MULTICAST(ntohl(pkt_dst.s_addr)) && IFNET_IS_WIFI_INFRA(ifp)) {
+               ip->ip_tos &= IPTOS_ECN_MASK;
+               mbuf_set_service_class(m, MBUF_SC_BE);
        }
-       
-       m->m_pkthdr.csum_flags &= IF_HWASSIST_CSUM_FLAGS(ifp->if_hwassist);
+
+       ip_output_checksum(ifp, m, (IP_VHL_HL(ip->ip_vhl) << 2),
+           ip->ip_len, &sw_csum);
 
        /*
         * If small enough for interface, or the interface will take
         * care of the fragmentation for us, can just send directly.
         */
-       if ((u_short)ip->ip_len <= ifp->if_mtu ||
-           ifp->if_hwassist & CSUM_FRAGMENT) {
+       if ((u_short)ip->ip_len <= ifp->if_mtu || TSO_IPV4_OK(ifp, m) ||
+           (!(ip->ip_off & IP_DF) && (ifp->if_hwassist & CSUM_FRAGMENT))) {
+#if BYTE_ORDER != BIG_ENDIAN
                HTONS(ip->ip_len);
                HTONS(ip->ip_off);
+#endif
+
                ip->ip_sum = 0;
                if (sw_csum & CSUM_DELAY_IP) {
-                       ip->ip_sum = in_cksum(m, hlen);
-               }
-               
-#ifndef __APPLE__
-               /* Record statistics for this interface address. */
-               if (!(flags & IP_FORWARDING) && ia != NULL) {
-                       ia->ia_ifa.if_opackets++;
-                       ia->ia_ifa.if_obytes += m->m_pkthdr.len;
+                       ip->ip_sum = ip_cksum_hdr_out(m, hlen);
+                       sw_csum &= ~CSUM_DELAY_IP;
+                       m->m_pkthdr.csum_flags &= ~CSUM_DELAY_IP;
                }
-#endif
 
 #if IPSEC
                /* clean ipsec history once it goes out of the node */
-               if (ipsec_bypass == 0 && (flags & IP_NOIPSEC) == 0)
+               if (ipsec_bypass == 0 && !(flags & IP_NOIPSEC))
                        ipsec_delaux(m);
-#endif
+#endif /* IPSEC */
+               if ((m->m_pkthdr.csum_flags & CSUM_TSO_IPV4) &&
+                   (m->m_pkthdr.tso_segsz > 0))
+                       scnt += m->m_pkthdr.len / m->m_pkthdr.tso_segsz;
+               else
+                       scnt++;
+
                if (packetchain == 0) {
-                       lck_mtx_unlock(ip_mutex);
-                       error = dlil_output(ifp, PF_INET, m, (void *) ro->ro_rt,
-                                   (struct sockaddr *)dst, 0);
-                       goto done;      
-               }
-               else { /* packet chaining allows us to reuse the route for all packets */
+                       if (ro->ro_rt != NULL && nstat_collect)
+                               nstat_route_tx(ro->ro_rt, scnt,
+                                   m->m_pkthdr.len, 0);
+
+                       error = dlil_output(ifp, PF_INET, m, ro->ro_rt,
+                           SA(dst), 0, adv);
+                       if (dlil_verbose && error) {
+                               printf("dlil_output error on interface %s: %d\n",
+                                       ifp->if_xname, error);
+                       }
+                       scnt = 0;
+                       goto done;
+               } else {
+                       /*
+                        * packet chaining allows us to reuse the
+                        * route for all packets
+                        */
+                       bytecnt += m->m_pkthdr.len;
+                       mppn = &m->m_nextpkt;
                        m = m->m_nextpkt;
                        if (m == NULL) {
+#if PF
+sendchain:
+#endif /* PF */
                                if (pktcnt > ip_maxchainsent)
                                        ip_maxchainsent = pktcnt;
-                               //send
-                               lck_mtx_unlock(ip_mutex);
-                               error = dlil_output_list(ifp, PF_INET, packetlist, (void *) ro->ro_rt,
-                                       (struct sockaddr *)dst, 0);
+                               if (ro->ro_rt != NULL && nstat_collect)
+                                       nstat_route_tx(ro->ro_rt, scnt,
+                                           bytecnt, 0);
+
+                               error = dlil_output(ifp, PF_INET, packetlist,
+                                   ro->ro_rt, SA(dst), 0, adv);
+                               if (dlil_verbose && error) {
+                                       printf("dlil_output error on interface %s: %d\n",
+                                       ifp->if_xname, error);
+                               }
                                pktcnt = 0;
+                               scnt = 0;
+                               bytecnt = 0;
                                goto done;
-       
+
                        }
                        m0 = m;
                        pktcnt++;
@@ -1224,8 +1902,10 @@ pass:
        /*
         * Too large for interface; fragment if possible.
         * Must be able to put at least 8 bytes per fragment.
+        * Balk when DF bit is set or the interface didn't support TSO.
         */
-       if (ip->ip_off & IP_DF) {
+       if ((ip->ip_off & IP_DF) || pktcnt > 0 ||
+           (m->m_pkthdr.csum_flags & CSUM_TSO_IPV4)) {
                error = EMSGSIZE;
                /*
                 * This case can happen if the user changed the MTU
@@ -1234,40 +1914,135 @@ pass:
                 * them, there is no way for one to update all its
                 * routes when the MTU is changed.
                 */
-               if (ro->ro_rt && (ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST))
-                   && !(ro->ro_rt->rt_rmx.rmx_locks & RTV_MTU)
-                   && (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
-                       ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
+               if (ro->ro_rt) {
+                       RT_LOCK_SPIN(ro->ro_rt);
+                       if ((ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
+                           !(ro->ro_rt->rt_rmx.rmx_locks & RTV_MTU) &&
+                           (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
+                               ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
+                       }
+                       RT_UNLOCK(ro->ro_rt);
                }
-               ipstat.ips_cantfrag++;
+               if (pktcnt > 0) {
+                       m0 = packetlist;
+               }
+               OSAddAtomic(1, &ipstat.ips_cantfrag);
                goto bad;
        }
-       len = (ifp->if_mtu - hlen) &~ 7;
-       if (len < 8) {
-               error = EMSGSIZE;
+
+       error = ip_fragment(m, ifp, ifp->if_mtu, sw_csum);
+       if (error != 0) {
+               m0 = m = NULL;
                goto bad;
        }
 
-       /*
-        * if the interface will not calculate checksums on
-        * fragmented packets, then do it here.
-        */
-       if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA &&
-           (ifp->if_hwassist & CSUM_IP_FRAGS) == 0) {
-               in_delayed_cksum(m);
-               if (m == NULL) {
-                       lck_mtx_unlock(ip_mutex);
-                       return(ENOMEM);
+       KERNEL_DEBUG(DBG_LAYER_END, ip->ip_dst.s_addr,
+           ip->ip_src.s_addr, ip->ip_p, ip->ip_off, ip->ip_len);
+
+       for (m = m0; m; m = m0) {
+               m0 = m->m_nextpkt;
+               m->m_nextpkt = 0;
+#if IPSEC
+               /* clean ipsec history once it goes out of the node */
+               if (ipsec_bypass == 0 && !(flags & IP_NOIPSEC))
+                       ipsec_delaux(m);
+#endif /* IPSEC */
+               if (error == 0) {
+                       if ((packetchain != 0) && (pktcnt > 0)) {
+                               panic("%s: mix of packet in packetlist is "
+                                   "wrong=%p", __func__, packetlist);
+                               /* NOTREACHED */
+                       }
+                       if (ro->ro_rt != NULL && nstat_collect) {
+                               nstat_route_tx(ro->ro_rt, 1,
+                                   m->m_pkthdr.len, 0);
+                       }
+                       error = dlil_output(ifp, PF_INET, m, ro->ro_rt,
+                           SA(dst), 0, adv);
+                       if (dlil_verbose && error) {
+                               printf("dlil_output error on interface %s: %d\n",
+                                          ifp->if_xname, error);
+                       }
+               } else {
+                       m_freem(m);
                }
-               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
        }
 
+       if (error == 0)
+               OSAddAtomic(1, &ipstat.ips_fragmented);
+
+done:
+       if (ia != NULL) {
+               IFA_REMREF(&ia->ia_ifa);
+               ia = NULL;
+       }
+#if IPSEC
+       ROUTE_RELEASE(&ipsec_state.ro);
+       if (sp != NULL) {
+               KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
+                   printf("DP ip_output call free SP:%x\n", sp));
+               key_freesp(sp, KEY_SADB_UNLOCKED);
+       }
+#endif /* IPSEC */
+#if NECP
+       ROUTE_RELEASE(&necp_route);
+#endif /* NECP */
+#if DUMMYNET
+       ROUTE_RELEASE(&saved_route);
+#endif /* DUMMYNET */
+#if IPFIREWALL_FORWARD
+       ROUTE_RELEASE(&sro_fwd);
+#endif /* IPFIREWALL_FORWARD */
+
+       KERNEL_DEBUG(DBG_FNC_IP_OUTPUT | DBG_FUNC_END, error, 0, 0, 0, 0);
+       if (ip_output_measure) {
+               net_perf_measure_time(&net_perf, &start_tv, packets_processed);
+               net_perf_histogram(&net_perf, packets_processed);
+       }
+       return (error);
+bad:
+       if (pktcnt > 0)
+               m0 = packetlist;
+       m_freem_list(m0);
+       goto done;
+
+#undef ipsec_state
+#undef args
+#undef sro_fwd
+#undef saved_route
+#undef ipf_pktopts
+#undef IP_CHECK_RESTRICTIONS
+}
 
-    {
-       int mhlen, firstlen = len;
-       struct mbuf **mnext = &m->m_nextpkt;
+int
+ip_fragment(struct mbuf *m, struct ifnet *ifp, unsigned long mtu, int sw_csum)
+{
+       struct ip *ip, *mhip;
+       int len, hlen, mhlen, firstlen, off, error = 0;
+       struct mbuf **mnext = &m->m_nextpkt, *m0;
        int nfrags = 1;
 
+       ip = mtod(m, struct ip *);
+#ifdef _IP_VHL
+       hlen = IP_VHL_HL(ip->ip_vhl) << 2;
+#else /* !_IP_VHL */
+       hlen = ip->ip_hl << 2;
+#endif /* !_IP_VHL */
+
+       firstlen = len = (mtu - hlen) &~ 7;
+       if (len < 8) {
+               m_freem(m);
+               return (EMSGSIZE);
+       }
+
+       /*
+        * if the interface will not calculate checksums on
+        * fragmented packets, then do it here.
+        */
+       if ((m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) &&
+           !(ifp->if_hwassist & CSUM_IP_FRAGS))
+               in_delayed_cksum(m);
+
        /*
         * Loop through length of segment after first fragment,
         * make new header and copy data of each part and link onto chain.
@@ -1275,10 +2050,10 @@ pass:
        m0 = m;
        mhlen = sizeof (struct ip);
        for (off = hlen + len; off < (u_short)ip->ip_len; off += len) {
-               MGETHDR(m, M_DONTWAIT, MT_HEADER);
-               if (m == 0) {
+               MGETHDR(m, M_DONTWAIT, MT_HEADER);      /* MAC-OK */
+               if (m == NULL) {
                        error = ENOBUFS;
-                       ipstat.ips_odropped++;
+                       OSAddAtomic(1, &ipstat.ips_odropped);
                        goto sendorfree;
                }
                m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
@@ -1299,26 +2074,37 @@ pass:
                        mhip->ip_off |= IP_MF;
                mhip->ip_len = htons((u_short)(len + mhlen));
                m->m_next = m_copy(m0, off, len);
-               if (m->m_next == 0) {
+               if (m->m_next == NULL) {
                        (void) m_free(m);
                        error = ENOBUFS;        /* ??? */
-                       ipstat.ips_odropped++;
+                       OSAddAtomic(1, &ipstat.ips_odropped);
                        goto sendorfree;
                }
                m->m_pkthdr.len = mhlen + len;
-               m->m_pkthdr.rcvif = 0;
+               m->m_pkthdr.rcvif = NULL;
                m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
-               m->m_pkthdr.socket_id = m0->m_pkthdr.socket_id;
+
+               M_COPY_CLASSIFIER(m, m0);
+               M_COPY_PFTAG(m, m0);
+
+#if CONFIG_MACF_NET
+               mac_netinet_fragment(m0, m);
+#endif /* CONFIG_MACF_NET */
+
+#if BYTE_ORDER != BIG_ENDIAN
                HTONS(mhip->ip_off);
+#endif
+
                mhip->ip_sum = 0;
                if (sw_csum & CSUM_DELAY_IP) {
-                       mhip->ip_sum = in_cksum(m, mhlen);
+                       mhip->ip_sum = ip_cksum_hdr_out(m, mhlen);
+                       m->m_pkthdr.csum_flags &= ~CSUM_DELAY_IP;
                }
                *mnext = m;
                mnext = &m->m_nextpkt;
                nfrags++;
        }
-       ipstat.ips_ofragments += nfrags;
+       OSAddAtomic(nfrags, &ipstat.ips_ofragments);
 
        /* set first/last markers for fragment chain */
        m->m_flags |= M_LASTFRAG;
@@ -1334,110 +2120,97 @@ pass:
        m->m_pkthdr.len = hlen + firstlen;
        ip->ip_len = htons((u_short)m->m_pkthdr.len);
        ip->ip_off |= IP_MF;
+
+#if BYTE_ORDER != BIG_ENDIAN
        HTONS(ip->ip_off);
+#endif
+
        ip->ip_sum = 0;
        if (sw_csum & CSUM_DELAY_IP) {
-               ip->ip_sum = in_cksum(m, hlen);
+               ip->ip_sum = ip_cksum_hdr_out(m, hlen);
+               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_IP;
        }
 sendorfree:
+       if (error)
+               m_freem_list(m0);
 
-       KERNEL_DEBUG(DBG_LAYER_END, ip->ip_dst.s_addr, 
-                    ip->ip_src.s_addr, ip->ip_p, ip->ip_off, ip->ip_len);
-
-       lck_mtx_unlock(ip_mutex);
-       for (m = m0; m; m = m0) {
-               m0 = m->m_nextpkt;
-               m->m_nextpkt = 0;
-#if IPSEC
-               /* clean ipsec history once it goes out of the node */
-               if (ipsec_bypass == 0 && (flags & IP_NOIPSEC) == 0)
-                       ipsec_delaux(m);
-#endif
-               if (error == 0) {
-#ifndef __APPLE__
-                       /* Record statistics for this interface address. */
-                       if (ia != NULL) {
-                               ia->ia_ifa.if_opackets++;
-                               ia->ia_ifa.if_obytes += m->m_pkthdr.len;
-                       }
-#endif
-                   if ((packetchain != 0)  && (pktcnt > 0))    
-                               panic("ip_output: mix of packet in packetlist is wrong=%x", packetlist);
-                   error = dlil_output(ifp, PF_INET, m, (void *) ro->ro_rt,
-                                       (struct sockaddr *)dst, 0);
-               } else
-                       m_freem(m);
-       }
-
-       if (error == 0)
-               ipstat.ips_fragmented++;
-    }
-done:
-       if (ia) {
-               ifafree(&ia->ia_ifa);
-               ia = NULL;
-       }
-#if IPSEC
-       if (ipsec_bypass == 0 && (flags & IP_NOIPSEC) == 0) {
-       if (ro == &iproute && ro->ro_rt) {
-               rtfree(ro->ro_rt);
-               ro->ro_rt = NULL;
-       }
-       if (sp != NULL) {
-               KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
-                       printf("DP ip_output call free SP:%x\n", sp));
-               lck_mtx_lock(sadb_mutex);
-               key_freesp(sp);
-               lck_mtx_unlock(sadb_mutex);
-       }
-       }
-#endif /* IPSEC */
-
-       KERNEL_DEBUG(DBG_FNC_IP_OUTPUT | DBG_FUNC_END, error,0,0,0,0);
        return (error);
-bad:
-       m_freem(m0);
-       lck_mtx_unlock(ip_mutex);
-       goto done;
 }
 
-void
-in_delayed_cksum_offset(struct mbuf *m0, int ip_offset)
+static void
+ip_out_cksum_stats(int proto, u_int32_t len)
 {
-       struct ip *ip;
-       unsigned char buf[sizeof(struct ip)];
-       u_short csum, offset, ip_len;
-       struct mbuf *m = m0;
-       
-       while (ip_offset >= m->m_len) {
-               ip_offset -= m->m_len;
-               m = m->m_next;
-               if (m == NULL) {
-                       printf("in_delayed_cksum_offset failed - ip_offset wasn't in the packet\n");
-                       return;
-               }
-       }
-       
-       /* Sometimes the IP header is not contiguous, yes this can happen! */
-       if (ip_offset + sizeof(struct ip) > m->m_len) {
-#if DEBUG              
-               printf("delayed m_pullup, m->len: %d  off: %d\n",
-                       m->m_len, ip_offset);
-#endif
-               m_copydata(m, ip_offset, sizeof(struct ip), buf);
-               
-               ip = (struct ip *)buf;
-       } else {
-               ip = (struct ip*)(m->m_data + ip_offset);
-       }
-       
-       /* Gross */
-       if (ip_offset) {
-               m->m_len -= ip_offset;
-               m->m_data += ip_offset;
+       switch (proto) {
+       case IPPROTO_TCP:
+               tcp_out_cksum_stats(len);
+               break;
+       case IPPROTO_UDP:
+               udp_out_cksum_stats(len);
+               break;
+       default:
+               /* keep only TCP or UDP stats for now */
+               break;
+       }
+}
+
+/*
+ * Process a delayed payload checksum calculation (outbound path.)
+ *
+ * hoff is the number of bytes beyond the mbuf data pointer which
+ * points to the IP header.
+ *
+ * Returns a bitmask representing all the work done in software.
+ */
+uint32_t
+in_finalize_cksum(struct mbuf *m, uint32_t hoff, uint32_t csum_flags)
+{
+       unsigned char buf[15 << 2] __attribute__((aligned(8)));
+       struct ip *ip;
+       uint32_t offset, _hlen, mlen, hlen, len, sw_csum;
+       uint16_t csum, ip_len;
+
+       _CASSERT(sizeof (csum) == sizeof (uint16_t));
+       VERIFY(m->m_flags & M_PKTHDR);
+
+       sw_csum = (csum_flags & m->m_pkthdr.csum_flags);
+
+       if ((sw_csum &= (CSUM_DELAY_IP | CSUM_DELAY_DATA)) == 0)
+               goto done;
+
+       mlen = m->m_pkthdr.len;                         /* total mbuf len */
+
+       /* sanity check (need at least simple IP header) */
+       if (mlen < (hoff + sizeof (*ip))) {
+               panic("%s: mbuf %p pkt len (%u) < hoff+ip_hdr "
+                   "(%u+%u)\n", __func__, m, mlen, hoff,
+                   (uint32_t)sizeof (*ip));
+               /* NOTREACHED */
+       }
+
+       /*
+        * In case the IP header is not contiguous, or not 32-bit aligned,
+        * or if we're computing the IP header checksum, copy it to a local
+        * buffer.  Copy only the simple IP header here (IP options case
+        * is handled below.)
+        */
+       if ((sw_csum & CSUM_DELAY_IP) || (hoff + sizeof (*ip)) > m->m_len ||
+           !IP_HDR_ALIGNED_P(mtod(m, caddr_t) + hoff)) {
+               m_copydata(m, hoff, sizeof (*ip), (caddr_t)buf);
+               ip = (struct ip *)(void *)buf;
+               _hlen = sizeof (*ip);
+       } else {
+               ip = (struct ip *)(void *)(m->m_data + hoff);
+               _hlen = 0;
+       }
+
+       hlen = IP_VHL_HL(ip->ip_vhl) << 2;              /* IP header len */
+
+       /* sanity check */
+       if (mlen < (hoff + hlen)) {
+               panic("%s: mbuf %p pkt too short (%d) for IP header (%u), "
+                   "hoff %u", __func__, m, mlen, hlen, hoff);
+               /* NOTREACHED */
        }
-       
-       offset = IP_VHL_HL(ip->ip_vhl) << 2 ;
 
        /*
         * We could be in the context of an IP or interface filter; in the
@@ -1445,148 +2218,117 @@ in_delayed_cksum_offset(struct mbuf *m0, int ip_offset)
         * the latter it would be in network order.  Because of this, we
         * attempt to interpret the length field by comparing it against
         * the actual packet length.  If the comparison fails, byte swap
-        * the length and check again.  If it still fails, then the packet
-        * is bogus and we give up.
+        * the length and check again.  If it still fails, use the actual
+        * packet length.  This also covers the trailing bytes case.
         */
        ip_len = ip->ip_len;
-       if (ip_len != (m0->m_pkthdr.len - ip_offset)) {
-               ip_len = SWAP16(ip_len);
-               if (ip_len != (m0->m_pkthdr.len - ip_offset)) {
-                       printf("in_delayed_cksum_offset: ip_len %d (%d) "
-                           "doesn't match actual length %d\n", ip->ip_len,
-                           ip_len, (m0->m_pkthdr.len - ip_offset));
-                       return;
+       if (ip_len != (mlen - hoff)) {
+               ip_len = OSSwapInt16(ip_len);
+               if (ip_len != (mlen - hoff)) {
+                       printf("%s: mbuf 0x%llx proto %d IP len %d (%x) "
+                           "[swapped %d (%x)] doesn't match actual packet "
+                           "length; %d is used instead\n", __func__,
+                           (uint64_t)VM_KERNEL_ADDRPERM(m), ip->ip_p,
+                           ip->ip_len, ip->ip_len, ip_len, ip_len,
+                           (mlen - hoff));
+                       ip_len = mlen - hoff;
                }
        }
 
-       csum = in_cksum_skip(m, ip_len, offset);
+       len = ip_len - hlen;                            /* csum span */
 
-       if (m0->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
-               csum = 0xffff;
-       offset += m0->m_pkthdr.csum_data & 0xFFFF;        /* checksum offset */
-
-       /* Gross */
-       if (ip_offset) {
-               if (M_LEADINGSPACE(m) < ip_offset)
-                       panic("in_delayed_cksum_offset - chain modified!\n");
-               m->m_len += ip_offset;
-               m->m_data -= ip_offset;
-       }
-
-       if (offset > ip_len) /* bogus offset */
-               return;
+       if (sw_csum & CSUM_DELAY_DATA) {
+               uint16_t ulpoff;
 
-       /* Insert the checksum in the existing chain */
-       if (offset + ip_offset + sizeof(u_short) > m->m_len) {
-               char tmp[2];
-               
-#if DEBUG
-               printf("delayed m_copyback, m->len: %d  off: %d  p: %d\n",
-                   m->m_len, offset + ip_offset, ip->ip_p);
-#endif
-               *(u_short *)tmp = csum;
-               m_copyback(m, offset + ip_offset, 2, tmp);
-       } else
-               *(u_short *)(m->m_data + offset + ip_offset) = csum;
-}
+               /*
+                * offset is added to the lower 16-bit value of csum_data,
+                * which is expected to contain the ULP offset; therefore
+                * CSUM_PARTIAL offset adjustment must be undone.
+                */
+               if ((m->m_pkthdr.csum_flags & (CSUM_PARTIAL|CSUM_DATA_VALID)) ==
+                   (CSUM_PARTIAL|CSUM_DATA_VALID)) {
+                       /*
+                        * Get back the original ULP offset (this will
+                        * undo the CSUM_PARTIAL logic in ip_output.)
+                        */
+                       m->m_pkthdr.csum_data = (m->m_pkthdr.csum_tx_stuff -
+                           m->m_pkthdr.csum_tx_start);
+               }
 
-void
-in_delayed_cksum(struct mbuf *m)
-{
-       in_delayed_cksum_offset(m, 0);
-}
+               ulpoff = (m->m_pkthdr.csum_data & 0xffff); /* ULP csum offset */
+               offset = hoff + hlen;                   /* ULP header */
 
-void
-in_cksum_offset(struct mbuf* m, size_t ip_offset)
-{
-       struct ip* ip = NULL;
-       int hlen = 0;
-       unsigned char buf[sizeof(struct ip)];
-       int swapped = 0;
-       
-       while (ip_offset >= m->m_len) {
-               ip_offset -= m->m_len;
-               m = m->m_next;
-               if (m == NULL) {
-                       printf("in_cksum_offset failed - ip_offset wasn't in the packet\n");
-                       return;
+               if (mlen < (ulpoff + sizeof (csum))) {
+                       panic("%s: mbuf %p pkt len (%u) proto %d invalid ULP "
+                           "cksum offset (%u) cksum flags 0x%x\n", __func__,
+                           m, mlen, ip->ip_p, ulpoff, m->m_pkthdr.csum_flags);
+                       /* NOTREACHED */
                }
-       }
-       
-       /* Sometimes the IP header is not contiguous, yes this can happen! */
-       if (ip_offset + sizeof(struct ip) > m->m_len) {
 
-#if DEBUG
-               printf("in_cksum_offset - delayed m_pullup, m->len: %d  off: %d\n",
-                       m->m_len, ip_offset);
-#endif 
-               m_copydata(m, ip_offset, sizeof(struct ip), buf);
+               csum = inet_cksum(m, 0, offset, len);
 
-               ip = (struct ip *)buf;
-               ip->ip_sum = 0;
-               m_copyback(m, ip_offset + offsetof(struct ip, ip_sum), 2, (caddr_t)&ip->ip_sum);
-       } else {
-               ip = (struct ip*)(m->m_data + ip_offset);
-               ip->ip_sum = 0;
-       }
-       
-       /* Gross */
-       if (ip_offset) {
-               m->m_len -= ip_offset;
-               m->m_data += ip_offset;
-       }
+               /* Update stats */
+               ip_out_cksum_stats(ip->ip_p, len);
 
-#ifdef _IP_VHL
-       hlen = IP_VHL_HL(ip->ip_vhl) << 2;
-#else
-       hlen = ip->ip_hl << 2;
-#endif
-       /*
-        * We could be in the context of an IP or interface filter; in the
-        * former case, ip_len would be in host order while for the latter
-        * it would be in network (correct) order.  Because of this, we
-        * attempt to interpret the length field by comparing it against
-        * the actual packet length.  If the comparison fails, byte swap
-        * the length and check again.  If it still fails, then the packet
-        * is bogus and we give up.
-        */
-       if (ntohs(ip->ip_len) != (m->m_pkthdr.len - ip_offset)) {
-               ip->ip_len = SWAP16(ip->ip_len);
-               swapped = 1;
-               if (ntohs(ip->ip_len) != (m->m_pkthdr.len - ip_offset)) {
-                       ip->ip_len = SWAP16(ip->ip_len);
-                       printf("in_cksum_offset: ip_len %d (%d) "
-                           "doesn't match actual length %d\n",
-                           ip->ip_len, SWAP16(ip->ip_len),
-                           (m->m_pkthdr.len - ip_offset));
-                       return;
+               /* RFC1122 4.1.3.4 */
+               if (csum == 0 &&
+                   (m->m_pkthdr.csum_flags & (CSUM_UDP|CSUM_ZERO_INVERT)))
+                       csum = 0xffff;
+
+               /* Insert the checksum in the ULP csum field */
+               offset += ulpoff;
+               if (offset + sizeof (csum) > m->m_len) {
+                       m_copyback(m, offset, sizeof (csum), &csum);
+               } else if (IP_HDR_ALIGNED_P(mtod(m, char *) + hoff)) {
+                       *(uint16_t *)(void *)(mtod(m, char *) + offset) = csum;
+               } else {
+                       bcopy(&csum, (mtod(m, char *) + offset), sizeof (csum));
                }
+               m->m_pkthdr.csum_flags &= ~(CSUM_DELAY_DATA | CSUM_DATA_VALID |
+                   CSUM_PARTIAL | CSUM_ZERO_INVERT);
        }
 
-       ip->ip_sum = 0;
-       ip->ip_sum = in_cksum(m, hlen);
-       if (swapped)
-               ip->ip_len = SWAP16(ip->ip_len);
+       if (sw_csum & CSUM_DELAY_IP) {
+               /* IP header must be in the local buffer */
+               VERIFY(_hlen == sizeof (*ip));
+               if (_hlen != hlen) {
+                       VERIFY(hlen <= sizeof (buf));
+                       m_copydata(m, hoff, hlen, (caddr_t)buf);
+                       ip = (struct ip *)(void *)buf;
+                       _hlen = hlen;
+               }
 
-       /* Gross */
-       if (ip_offset) {
-               if (M_LEADINGSPACE(m) < ip_offset)
-                       panic("in_cksum_offset - chain modified!\n");
-               m->m_len += ip_offset;
-               m->m_data -= ip_offset;
-       }
+               /*
+                * Compute the IP header checksum as if the IP length
+                * is the length which we believe is "correct"; see
+                * how ip_len gets calculated above.  Note that this
+                * is done on the local copy and not on the real one.
+                */
+               ip->ip_len = htons(ip_len);
+               ip->ip_sum = 0;
+               csum = in_cksum_hdr_opt(ip);
 
-       /* Insert the checksum in the existing chain if IP header not contiguous */
-       if (ip_offset + sizeof(struct ip) > m->m_len) {
-               char tmp[2];
+               /* Update stats */
+               ipstat.ips_snd_swcsum++;
+               ipstat.ips_snd_swcsum_bytes += hlen;
 
-#if DEBUG
-               printf("in_cksum_offset m_copyback, m->len: %d  off: %d  p: %d\n",
-                   m->m_len, ip_offset + offsetof(struct ip, ip_sum), ip->ip_p);
-#endif
-               *(u_short *)tmp = ip->ip_sum;
-               m_copyback(m, ip_offset + offsetof(struct ip, ip_sum), 2, tmp);
+               /*
+                * Insert only the checksum in the existing IP header
+                * csum field; all other fields are left unchanged.
+                */
+               offset = hoff + offsetof(struct ip, ip_sum);
+               if (offset + sizeof (csum) > m->m_len) {
+                       m_copyback(m, offset, sizeof (csum), &csum);
+               } else if (IP_HDR_ALIGNED_P(mtod(m, char *) + hoff)) {
+                       *(uint16_t *)(void *)(mtod(m, char *) + offset) = csum;
+               } else {
+                       bcopy(&csum, (mtod(m, char *) + offset), sizeof (csum));
+               }
+               m->m_pkthdr.csum_flags &= ~CSUM_DELAY_IP;
        }
+
+done:
+       return (sw_csum);
 }
 
 /*
@@ -1597,43 +2339,43 @@ in_cksum_offset(struct mbuf* m, size_t ip_offset)
  * XXX This routine assumes that the packet has no options in place.
  */
 static struct mbuf *
-ip_insertoptions(m, opt, phlen)
-       register struct mbuf *m;
-       struct mbuf *opt;
-       int *phlen;
+ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
 {
-       register struct ipoption *p = mtod(opt, struct ipoption *);
+       struct ipoption *p = mtod(opt, struct ipoption *);
        struct mbuf *n;
-       register struct ip *ip = mtod(m, struct ip *);
+       struct ip *ip = mtod(m, struct ip *);
        unsigned optlen;
 
-       optlen = opt->m_len - sizeof(p->ipopt_dst);
+       optlen = opt->m_len - sizeof (p->ipopt_dst);
        if (optlen + (u_short)ip->ip_len > IP_MAXPACKET)
                return (m);             /* XXX should fail */
        if (p->ipopt_dst.s_addr)
                ip->ip_dst = p->ipopt_dst;
        if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
-               MGETHDR(n, M_DONTWAIT, MT_HEADER);
-               if (n == 0)
+               MGETHDR(n, M_DONTWAIT, MT_HEADER);      /* MAC-OK */
+               if (n == NULL)
                        return (m);
                n->m_pkthdr.rcvif = 0;
+#if CONFIG_MACF_NET
+               mac_mbuf_label_copy(m, n);
+#endif /* CONFIG_MACF_NET */
                n->m_pkthdr.len = m->m_pkthdr.len + optlen;
-               m->m_len -= sizeof(struct ip);
-               m->m_data += sizeof(struct ip);
+               m->m_len -= sizeof (struct ip);
+               m->m_data += sizeof (struct ip);
                n->m_next = m;
                m = n;
-               m->m_len = optlen + sizeof(struct ip);
+               m->m_len = optlen + sizeof (struct ip);
                m->m_data += max_linkhdr;
-               (void)memcpy(mtod(m, void *), ip, sizeof(struct ip));
+               (void) memcpy(mtod(m, void *), ip, sizeof (struct ip));
        } else {
                m->m_data -= optlen;
                m->m_len += optlen;
                m->m_pkthdr.len += optlen;
-               ovbcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
+               ovbcopy((caddr_t)ip, mtod(m, caddr_t), sizeof (struct ip));
        }
        ip = mtod(m, struct ip *);
        bcopy(p->ipopt_list, ip + 1, optlen);
-       *phlen = sizeof(struct ip) + optlen;
+       *phlen = sizeof (struct ip) + optlen;
        ip->ip_vhl = IP_MAKE_VHL(IPVERSION, *phlen >> 2);
        ip->ip_len += optlen;
        return (m);
@@ -1643,11 +2385,10 @@ ip_insertoptions(m, opt, phlen)
  * Copy options from ip to jp,
  * omitting those not copied during fragmentation.
  */
-int
-ip_optcopy(ip, jp)
-       struct ip *ip, *jp;
+static int
+ip_optcopy(struct ip *ip, struct ip *jp)
 {
-       register u_char *cp, *dp;
+       u_char *cp, *dp;
        int opt, optlen, cnt;
 
        cp = (u_char *)(ip + 1);
@@ -1664,13 +2405,17 @@ ip_optcopy(ip, jp)
                        continue;
                }
 #if DIAGNOSTIC
-               if (cnt < IPOPT_OLEN + sizeof(*cp))
+               if (cnt < IPOPT_OLEN + sizeof (*cp)) {
                        panic("malformed IPv4 option passed to ip_optcopy");
+                       /* NOTREACHED */
+               }
 #endif
                optlen = cp[IPOPT_OLEN];
 #if DIAGNOSTIC
-               if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
+               if (optlen < IPOPT_OLEN + sizeof (*cp) || optlen > cnt) {
                        panic("malformed IPv4 option passed to ip_optcopy");
+                       /* NOTREACHED */
+               }
 #endif
                /* bogus lengths should have been caught by ip_dooptions */
                if (optlen > cnt)
@@ -1689,44 +2434,44 @@ ip_optcopy(ip, jp)
  * IP socket option processing.
  */
 int
-ip_ctloutput(so, sopt)
-       struct socket *so;
-       struct sockopt *sopt;
+ip_ctloutput(struct socket *so, struct sockopt *sopt)
 {
        struct  inpcb *inp = sotoinpcb(so);
        int     error, optval;
 
        error = optval = 0;
-       if (sopt->sopt_level != IPPROTO_IP) {
+       if (sopt->sopt_level != IPPROTO_IP)
                return (EINVAL);
-       }
 
        switch (sopt->sopt_dir) {
        case SOPT_SET:
                switch (sopt->sopt_name) {
-               case IP_OPTIONS:
 #ifdef notyet
                case IP_RETOPTS:
 #endif
-               {
+               case IP_OPTIONS: {
                        struct mbuf *m;
+
                        if (sopt->sopt_valsize > MLEN) {
                                error = EMSGSIZE;
                                break;
                        }
-                       MGET(m, sopt->sopt_p ? M_WAIT : M_DONTWAIT, MT_HEADER);
-                       if (m == 0) {
+                       MGET(m, sopt->sopt_p != kernproc ? M_WAIT : M_DONTWAIT,
+                           MT_HEADER);
+                       if (m == NULL) {
                                error = ENOBUFS;
                                break;
                        }
                        m->m_len = sopt->sopt_valsize;
-                       error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
-                                           m->m_len);
-                       if (error)
+                       error = sooptcopyin(sopt, mtod(m, char *),
+                           m->m_len, m->m_len);
+                       if (error) {
+                               m_freem(m);
                                break;
-                       
-                       return (ip_pcbopts(sopt->sopt_name, &inp->inp_options,
-                                          m));
+                       }
+
+                       return (ip_pcbopts(sopt->sopt_name,
+                           &inp->inp_options, m));
                }
 
                case IP_TOS:
@@ -1736,11 +2481,10 @@ ip_ctloutput(so, sopt)
                case IP_RECVDSTADDR:
                case IP_RECVIF:
                case IP_RECVTTL:
-#if defined(NFAITH) && NFAITH > 0
-               case IP_FAITH:
-#endif
-                       error = sooptcopyin(sopt, &optval, sizeof optval,
-                                           sizeof optval);
+               case IP_RECVPKTINFO:
+               case IP_RECVTOS:
+                       error = sooptcopyin(sopt, &optval, sizeof (optval),
+                           sizeof (optval));
                        if (error)
                                break;
 
@@ -1778,27 +2522,44 @@ ip_ctloutput(so, sopt)
                                OPTSET(INP_RECVTTL);
                                break;
 
-#if defined(NFAITH) && NFAITH > 0
-                       case IP_FAITH:
-                               OPTSET(INP_FAITH);
+                       case IP_RECVPKTINFO:
+                               OPTSET(INP_PKTINFO);
                                break;
-#endif
+
+                       case IP_RECVTOS:
+                               OPTSET(INP_RECVTOS);
+                               break;
+ #undef OPTSET
                        }
                        break;
-#undef OPTSET
-
+               /*
+                * Multicast socket options are processed by the in_mcast
+                * module.
+                */
                case IP_MULTICAST_IF:
+               case IP_MULTICAST_IFINDEX:
                case IP_MULTICAST_VIF:
                case IP_MULTICAST_TTL:
                case IP_MULTICAST_LOOP:
                case IP_ADD_MEMBERSHIP:
                case IP_DROP_MEMBERSHIP:
-                       error = ip_setmoptions(sopt, &inp->inp_moptions);
+               case IP_ADD_SOURCE_MEMBERSHIP:
+               case IP_DROP_SOURCE_MEMBERSHIP:
+               case IP_BLOCK_SOURCE:
+               case IP_UNBLOCK_SOURCE:
+               case IP_MSFILTER:
+               case MCAST_JOIN_GROUP:
+               case MCAST_LEAVE_GROUP:
+               case MCAST_JOIN_SOURCE_GROUP:
+               case MCAST_LEAVE_SOURCE_GROUP:
+               case MCAST_BLOCK_SOURCE:
+               case MCAST_UNBLOCK_SOURCE:
+                       error = inp_setmoptions(inp, sopt);
                        break;
 
                case IP_PORTRANGE:
-                       error = sooptcopyin(sopt, &optval, sizeof optval,
-                                           sizeof optval);
+                       error = sooptcopyin(sopt, &optval, sizeof (optval),
+                           sizeof (optval));
                        if (error)
                                break;
 
@@ -1825,36 +2586,111 @@ ip_ctloutput(so, sopt)
                        break;
 
 #if IPSEC
-               case IP_IPSEC_POLICY:
-               {
+               case IP_IPSEC_POLICY: {
                        caddr_t req = NULL;
                        size_t len = 0;
                        int priv;
                        struct mbuf *m;
                        int optname;
 
-                        if (sopt->sopt_valsize > MCLBYTES) {
-                                error = EMSGSIZE;
-                                break;
-                        }
                        if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
                                break;
                        if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
                                break;
-                       priv = (sopt->sopt_p != NULL &&
-                               proc_suser(sopt->sopt_p) != 0) ? 0 : 1;
+                       priv = (proc_suser(sopt->sopt_p) == 0);
                        if (m) {
                                req = mtod(m, caddr_t);
                                len = m->m_len;
                        }
                        optname = sopt->sopt_name;
-                       lck_mtx_lock(sadb_mutex);
                        error = ipsec4_set_policy(inp, optname, req, len, priv);
-                       lck_mtx_unlock(sadb_mutex);
                        m_freem(m);
                        break;
                }
-#endif /*IPSEC*/
+#endif /* IPSEC */
+
+#if TRAFFIC_MGT
+               case IP_TRAFFIC_MGT_BACKGROUND: {
+                       unsigned background = 0;
+
+                       error = sooptcopyin(sopt, &background,
+                           sizeof (background), sizeof (background));
+                       if (error)
+                               break;
+
+                       if (background) {
+                               socket_set_traffic_mgt_flags_locked(so,
+                                   TRAFFIC_MGT_SO_BACKGROUND);
+                       } else {
+                               socket_clear_traffic_mgt_flags_locked(so,
+                                   TRAFFIC_MGT_SO_BACKGROUND);
+                       }
+
+                       break;
+               }
+#endif /* TRAFFIC_MGT */
+
+               /*
+                * On a multihomed system, scoped routing can be used to
+                * restrict the source interface used for sending packets.
+                * The socket option IP_BOUND_IF binds a particular AF_INET
+                * socket to an interface such that data sent on the socket
+                * is restricted to that interface.  This is unlike the
+                * SO_DONTROUTE option where the routing table is bypassed;
+                * therefore it allows for a greater flexibility and control
+                * over the system behavior, and does not place any restriction
+                * on the destination address type (e.g.  unicast, multicast,
+                * or broadcast if applicable) or whether or not the host is
+                * directly reachable.  Note that in the multicast transmit
+                * case, IP_MULTICAST_{IF,IFINDEX} takes precedence over
+                * IP_BOUND_IF, since the former practically bypasses the
+                * routing table; in this case, IP_BOUND_IF sets the default
+                * interface used for sending multicast packets in the absence
+                * of an explicit multicast transmit interface.
+                */
+               case IP_BOUND_IF:
+                       /* This option is settable only for IPv4 */
+                       if (!(inp->inp_vflag & INP_IPV4)) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       error = sooptcopyin(sopt, &optval, sizeof (optval),
+                           sizeof (optval));
+
+                       if (error)
+                               break;
+
+                       error = inp_bindif(inp, optval, NULL);
+                       break;
+
+               case IP_NO_IFT_CELLULAR:
+                       /* This option is settable only for IPv4 */
+                       if (!(inp->inp_vflag & INP_IPV4)) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       error = sooptcopyin(sopt, &optval, sizeof (optval),
+                           sizeof (optval));
+
+                       if (error)
+                               break;
+
+                       /* once set, it cannot be unset */
+                       if (!optval && INP_NO_CELLULAR(inp)) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       error = so_set_restrictions(so,
+                           SO_RESTRICT_DENY_CELLULAR);
+                       break;
+
+               case IP_OUT_IF:
+                       /* This option is not settable */
+                       error = EINVAL;
+                       break;
 
                default:
                        error = ENOPROTOOPT;
@@ -1866,13 +2702,13 @@ ip_ctloutput(so, sopt)
                switch (sopt->sopt_name) {
                case IP_OPTIONS:
                case IP_RETOPTS:
-                       if (inp->inp_options)
-                               error = sooptcopyout(sopt, 
-                                                    mtod(inp->inp_options,
-                                                         char *),
-                                                    inp->inp_options->m_len);
-                       else
+                       if (inp->inp_options) {
+                               error = sooptcopyout(sopt,
+                                   mtod(inp->inp_options, char *),
+                                   inp->inp_options->m_len);
+                       } else {
                                sopt->sopt_valsize = 0;
+                       }
                        break;
 
                case IP_TOS:
@@ -1883,11 +2719,9 @@ ip_ctloutput(so, sopt)
                case IP_RECVIF:
                case IP_RECVTTL:
                case IP_PORTRANGE:
-#if defined(NFAITH) && NFAITH > 0
-               case IP_FAITH:
-#endif
+               case IP_RECVPKTINFO:
+               case IP_RECVTOS:
                        switch (sopt->sopt_name) {
-
                        case IP_TOS:
                                optval = inp->inp_ip_tos;
                                break;
@@ -1927,45 +2761,58 @@ ip_ctloutput(so, sopt)
                                        optval = 0;
                                break;
 
-#if defined(NFAITH) && NFAITH > 0
-                       case IP_FAITH:
-                               optval = OPTBIT(INP_FAITH);
+                       case IP_RECVPKTINFO:
+                               optval = OPTBIT(INP_PKTINFO);
+                               break;
+
+                       case IP_RECVTOS:
+                               optval = OPTBIT(INP_RECVTOS);
                                break;
-#endif
                        }
-                       error = sooptcopyout(sopt, &optval, sizeof optval);
+                       error = sooptcopyout(sopt, &optval, sizeof (optval));
                        break;
 
                case IP_MULTICAST_IF:
+               case IP_MULTICAST_IFINDEX:
                case IP_MULTICAST_VIF:
                case IP_MULTICAST_TTL:
                case IP_MULTICAST_LOOP:
-               case IP_ADD_MEMBERSHIP:
-               case IP_DROP_MEMBERSHIP:
-                       error = ip_getmoptions(sopt, inp->inp_moptions);
+               case IP_MSFILTER:
+                       error = inp_getmoptions(inp, sopt);
                        break;
 
 #if IPSEC
-               case IP_IPSEC_POLICY:
-               {
-                       struct mbuf *m = NULL;
-                       caddr_t req = NULL;
-                       size_t len = 0;
-
-                       if (m != 0) {
-                               req = mtod(m, caddr_t);
-                               len = m->m_len;
-                       }
-                       lck_mtx_lock(sadb_mutex);
-                       error = ipsec4_get_policy(sotoinpcb(so), req, len, &m);
-                       lck_mtx_unlock(sadb_mutex);
-                       if (error == 0)
-                               error = soopt_mcopyout(sopt, m); /* XXX */
-                       if (error == 0)
-                               m_freem(m);
+               case IP_IPSEC_POLICY: {
+                       error = 0; /* This option is no longer supported */
                        break;
                }
-#endif /*IPSEC*/
+#endif /* IPSEC */
+
+#if TRAFFIC_MGT
+               case IP_TRAFFIC_MGT_BACKGROUND: {
+                       unsigned background = (so->so_flags1 &
+                           SOF1_TRAFFIC_MGT_SO_BACKGROUND) ? 1 : 0;
+                       return (sooptcopyout(sopt, &background,
+                           sizeof (background)));
+               }
+#endif /* TRAFFIC_MGT */
+
+               case IP_BOUND_IF:
+                       if (inp->inp_flags & INP_BOUND_IF)
+                               optval = inp->inp_boundifp->if_index;
+                       error = sooptcopyout(sopt, &optval, sizeof (optval));
+                       break;
+
+               case IP_NO_IFT_CELLULAR:
+                       optval = INP_NO_CELLULAR(inp) ? 1 : 0;
+                       error = sooptcopyout(sopt, &optval, sizeof (optval));
+                       break;
+
+               case IP_OUT_IF:
+                       optval = (inp->inp_last_outifp != NULL) ?
+                           inp->inp_last_outifp->if_index : 0;
+                       error = sooptcopyout(sopt, &optval, sizeof (optval));
+                       break;
 
                default:
                        error = ENOPROTOOPT;
@@ -1982,44 +2829,41 @@ ip_ctloutput(so, sopt)
  * with destination address if source routed.
  */
 static int
-ip_pcbopts(optname, pcbopt, m)
-       int optname;
-       struct mbuf **pcbopt;
-       register struct mbuf *m;
+ip_pcbopts(int optname, struct mbuf **pcbopt, struct mbuf *m)
 {
-       register int cnt, optlen;
-       register u_char *cp;
+#pragma unused(optname)
+       int cnt, optlen;
+       u_char *cp;
        u_char opt;
 
        /* turn off any old options */
        if (*pcbopt)
-               (void)m_free(*pcbopt);
+               (void) m_free(*pcbopt);
        *pcbopt = 0;
        if (m == (struct mbuf *)0 || m->m_len == 0) {
                /*
                 * Only turning off any previous options.
                 */
                if (m)
-                       (void)m_free(m);
+                       (void) m_free(m);
                return (0);
        }
 
-#ifndef        vax
-       if (m->m_len % sizeof(int32_t))
+       if (m->m_len % sizeof (int32_t))
                goto bad;
-#endif
+
        /*
         * IP first-hop destination address will be stored before
         * actual options; move other options back
         * and clear it when none present.
         */
-       if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
+       if (m->m_data + m->m_len + sizeof (struct in_addr) >= &m->m_dat[MLEN])
                goto bad;
        cnt = m->m_len;
-       m->m_len += sizeof(struct in_addr);
-       cp = mtod(m, u_char *) + sizeof(struct in_addr);
+       m->m_len += sizeof (struct in_addr);
+       cp = mtod(m, u_char *) + sizeof (struct in_addr);
        ovbcopy(mtod(m, caddr_t), (caddr_t)cp, (unsigned)cnt);
-       bzero(mtod(m, caddr_t), sizeof(struct in_addr));
+       bzero(mtod(m, caddr_t), sizeof (struct in_addr));
 
        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                opt = cp[IPOPT_OPTVAL];
@@ -2028,10 +2872,10 @@ ip_pcbopts(optname, pcbopt, m)
                if (opt == IPOPT_NOP)
                        optlen = 1;
                else {
-                       if (cnt < IPOPT_OLEN + sizeof(*cp))
+                       if (cnt < IPOPT_OLEN + sizeof (*cp))
                                goto bad;
                        optlen = cp[IPOPT_OLEN];
-                       if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
+                       if (optlen < IPOPT_OLEN + sizeof (*cp) || optlen > cnt)
                                goto bad;
                }
                switch (opt) {
@@ -2049,587 +2893,683 @@ ip_pcbopts(optname, pcbopt, m)
                         * A is first hop destination, which doesn't appear in
                         * actual IP option, but is stored before the options.
                         */
-                       if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
+                       if (optlen < IPOPT_MINOFF - 1 + sizeof (struct in_addr))
                                goto bad;
-                       m->m_len -= sizeof(struct in_addr);
-                       cnt -= sizeof(struct in_addr);
-                       optlen -= sizeof(struct in_addr);
+                       m->m_len -= sizeof (struct in_addr);
+                       cnt -= sizeof (struct in_addr);
+                       optlen -= sizeof (struct in_addr);
                        cp[IPOPT_OLEN] = optlen;
                        /*
                         * Move first hop before start of options.
                         */
                        bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
-                           sizeof(struct in_addr));
+                           sizeof (struct in_addr));
                        /*
                         * Then copy rest of options back
                         * to close up the deleted entry.
                         */
                        ovbcopy((caddr_t)(&cp[IPOPT_OFFSET+1] +
-                           sizeof(struct in_addr)),
+                           sizeof (struct in_addr)),
                            (caddr_t)&cp[IPOPT_OFFSET+1],
-                           (unsigned)cnt + sizeof(struct in_addr));
+                           (unsigned)cnt + sizeof (struct in_addr));
                        break;
                }
        }
-       if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
+       if (m->m_len > MAX_IPOPTLEN + sizeof (struct in_addr))
                goto bad;
        *pcbopt = m;
        return (0);
 
 bad:
-       (void)m_free(m);
+       (void) m_free(m);
        return (EINVAL);
 }
 
-/*
- * XXX
- * The whole multicast option thing needs to be re-thought.
- * Several of these options are equally applicable to non-multicast
- * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
- * standard option (IP_TTL).
- */
+void
+ip_moptions_init(void)
+{
+       PE_parse_boot_argn("ifa_debug", &imo_debug, sizeof (imo_debug));
 
-/*
- * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
- */
-static struct ifnet *
-ip_multicast_if(a, ifindexp)
-       struct in_addr *a;
-       int *ifindexp;
+       imo_size = (imo_debug == 0) ? sizeof (struct ip_moptions) :
+           sizeof (struct ip_moptions_dbg);
+
+       imo_zone = zinit(imo_size, IMO_ZONE_MAX * imo_size, 0,
+           IMO_ZONE_NAME);
+       if (imo_zone == NULL) {
+               panic("%s: failed allocating %s", __func__, IMO_ZONE_NAME);
+               /* NOTREACHED */
+       }
+       zone_change(imo_zone, Z_EXPAND, TRUE);
+}
+
+void
+imo_addref(struct ip_moptions *imo, int locked)
 {
-       int ifindex;
-       struct ifnet *ifp;
-
-       if (ifindexp)
-               *ifindexp = 0;
-       if (ntohl(a->s_addr) >> 24 == 0) {
-               ifindex = ntohl(a->s_addr) & 0xffffff;
-               ifnet_head_lock_shared();
-               if (ifindex < 0 || if_index < ifindex) {
-                       ifnet_head_done();
-                       return NULL;
-               }
-               ifp = ifindex2ifnet[ifindex];
-               ifnet_head_done();
-               if (ifindexp)
-                       *ifindexp = ifindex;
-       } else {
-               INADDR_TO_IFP(*a, ifp);
+       if (!locked)
+               IMO_LOCK(imo);
+       else
+               IMO_LOCK_ASSERT_HELD(imo);
+
+       if (++imo->imo_refcnt == 0) {
+               panic("%s: imo %p wraparound refcnt\n", __func__, imo);
+               /* NOTREACHED */
+       } else if (imo->imo_trace != NULL) {
+               (*imo->imo_trace)(imo, TRUE);
        }
-       return ifp;
+
+       if (!locked)
+               IMO_UNLOCK(imo);
 }
 
-/*
- * Set the IP multicast options in response to user setsockopt().
- */
-static int
-ip_setmoptions(sopt, imop)
-       struct sockopt *sopt;
-       struct ip_moptions **imop;
+void
+imo_remref(struct ip_moptions *imo)
 {
-       int error = 0;
        int i;
-       struct in_addr addr;
-       struct ip_mreq mreq;
-       struct ifnet *ifp = NULL;
-       struct ip_moptions *imo = *imop;
-       int ifindex;
 
-       if (imo == NULL) {
-               /*
-                * No multicast option buffer attached to the pcb;
-                * allocate one and initialize to default values.
-                */
-               error = ip_createmoptions(imop);
-               if (error != 0)
-                       return error;
-               imo = *imop;
+       IMO_LOCK(imo);
+       if (imo->imo_refcnt == 0) {
+               panic("%s: imo %p negative refcnt", __func__, imo);
+               /* NOTREACHED */
+       } else if (imo->imo_trace != NULL) {
+               (*imo->imo_trace)(imo, FALSE);
        }
 
-       switch (sopt->sopt_name) {
-       /* store an index number for the vif you wanna use in the send */
-       case IP_MULTICAST_VIF:
-               if (legal_vif_num == 0) {
-                       error = EOPNOTSUPP;
-                       break;
-               }
-               error = sooptcopyin(sopt, &i, sizeof i, sizeof i);
-               if (error)
-                       break;
-               if (!legal_vif_num(i) && (i != -1)) {
-                       error = EINVAL;
-                       break;
-               }
-               imo->imo_multicast_vif = i;
-               break;
+       --imo->imo_refcnt;
+       if (imo->imo_refcnt > 0) {
+               IMO_UNLOCK(imo);
+               return;
+       }
 
-       case IP_MULTICAST_IF:
-               /*
-                * Select the interface for outgoing multicast packets.
-                */
-               error = sooptcopyin(sopt, &addr, sizeof addr, sizeof addr);
-               if (error)
-                       break;
-               /*
-                * INADDR_ANY is used to remove a previous selection.
-                * When no interface is selected, a default one is
-                * chosen every time a multicast packet is sent.
-                */
-               if (addr.s_addr == INADDR_ANY) {
-                       imo->imo_multicast_ifp = NULL;
-                       break;
-               }
-               /*
-                * The selected interface is identified by its local
-                * IP address.  Find the interface and confirm that
-                * it supports multicasting.
-                */
-               ifp = ip_multicast_if(&addr, &ifindex);
-               if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
-                       error = EADDRNOTAVAIL;
-                       break;
-               }
-               imo->imo_multicast_ifp = ifp;
-               if (ifindex)
-                       imo->imo_multicast_addr = addr;
-               else
-                       imo->imo_multicast_addr.s_addr = INADDR_ANY;
-               break;
+       for (i = 0; i < imo->imo_num_memberships; ++i) {
+               struct in_mfilter *imf;
 
-       case IP_MULTICAST_TTL:
-               /*
-                * Set the IP time-to-live for outgoing multicast packets.
-                * The original multicast API required a char argument,
-                * which is inconsistent with the rest of the socket API.
-                * We allow either a char or an int.
-                */
-               if (sopt->sopt_valsize == 1) {
-                       u_char ttl;
-                       error = sooptcopyin(sopt, &ttl, 1, 1);
-                       if (error)
-                               break;
-                       imo->imo_multicast_ttl = ttl;
-               } else {
-                       u_int ttl;
-                       error = sooptcopyin(sopt, &ttl, sizeof ttl, 
-                                           sizeof ttl);
-                       if (error)
-                               break;
-                       if (ttl > 255)
-                               error = EINVAL;
-                       else
-                               imo->imo_multicast_ttl = ttl;
-               }
-               break;
+               imf = imo->imo_mfilters ? &imo->imo_mfilters[i] : NULL;
+               if (imf != NULL)
+                       imf_leave(imf);
 
-       case IP_MULTICAST_LOOP:
-               /*
-                * Set the loopback flag for outgoing multicast packets.
-                * Must be zero or one.  The original multicast API required a
-                * char argument, which is inconsistent with the rest
-                * of the socket API.  We allow either a char or an int.
-                */
-               if (sopt->sopt_valsize == 1) {
-                       u_char loop;
-                       error = sooptcopyin(sopt, &loop, 1, 1);
-                       if (error)
-                               break;
-                       imo->imo_multicast_loop = !!loop;
-               } else {
-                       u_int loop;
-                       error = sooptcopyin(sopt, &loop, sizeof loop,
-                                           sizeof loop);
-                       if (error)
-                               break;
-                       imo->imo_multicast_loop = !!loop;
-               }
-               break;
+               (void) in_leavegroup(imo->imo_membership[i], imf);
 
-       case IP_ADD_MEMBERSHIP:
-               /*
-                * Add a multicast group membership.
-                * Group must be a valid IP multicast address.
-                */
-               error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
-               if (error)
-                       break;
-               
-               error = ip_addmembership(imo, &mreq);
-               break;
+               if (imf != NULL)
+                       imf_purge(imf);
 
-       case IP_DROP_MEMBERSHIP:
-               /*
-                * Drop a multicast group membership.
-                * Group must be a valid IP multicast address.
-                */
-               error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
-               if (error)
-                       break;
-               
-               error = ip_dropmembership(imo, &mreq);
-               break;
+               INM_REMREF(imo->imo_membership[i]);
+               imo->imo_membership[i] = NULL;
+       }
+       imo->imo_num_memberships = 0;
+       if (imo->imo_mfilters != NULL) {
+               FREE(imo->imo_mfilters, M_INMFILTER);
+               imo->imo_mfilters = NULL;
+       }
+       if (imo->imo_membership != NULL) {
+               FREE(imo->imo_membership, M_IPMOPTS);
+               imo->imo_membership = NULL;
+       }
+       IMO_UNLOCK(imo);
 
-       default:
-               error = EOPNOTSUPP;
-               break;
+       lck_mtx_destroy(&imo->imo_lock, ifa_mtx_grp);
+
+       if (!(imo->imo_debug & IFD_ALLOC)) {
+               panic("%s: imo %p cannot be freed", __func__, imo);
+               /* NOTREACHED */
        }
+       zfree(imo_zone, imo);
+}
 
-       /*
-        * If all options have default values, no need to keep the mbuf.
-        */
-       if (imo->imo_multicast_ifp == NULL &&
-           imo->imo_multicast_vif == -1 &&
-           imo->imo_multicast_ttl == IP_DEFAULT_MULTICAST_TTL &&
-           imo->imo_multicast_loop == IP_DEFAULT_MULTICAST_LOOP &&
-           imo->imo_num_memberships == 0) {
-               FREE(*imop, M_IPMOPTS);
-               *imop = NULL;
+static void
+imo_trace(struct ip_moptions *imo, int refhold)
+{
+       struct ip_moptions_dbg *imo_dbg = (struct ip_moptions_dbg *)imo;
+       ctrace_t *tr;
+       u_int32_t idx;
+       u_int16_t *cnt;
+
+       if (!(imo->imo_debug & IFD_DEBUG)) {
+               panic("%s: imo %p has no debug structure", __func__, imo);
+               /* NOTREACHED */
+       }
+       if (refhold) {
+               cnt = &imo_dbg->imo_refhold_cnt;
+               tr = imo_dbg->imo_refhold;
+       } else {
+               cnt = &imo_dbg->imo_refrele_cnt;
+               tr = imo_dbg->imo_refrele;
        }
 
-       return (error);
+       idx = atomic_add_16_ov(cnt, 1) % IMO_TRACE_HIST_SIZE;
+       ctrace_record(&tr[idx]);
 }
 
-/*
- * Set the IP multicast options in response to user setsockopt().
- */
-__private_extern__ int
-ip_createmoptions(
-       struct ip_moptions **imop)
+struct ip_moptions *
+ip_allocmoptions(int how)
 {
        struct ip_moptions *imo;
-       imo = (struct ip_moptions*) _MALLOC(sizeof(*imo), M_IPMOPTS,
-               M_WAITOK);
-
-       if (imo == NULL)
-               return (ENOBUFS);
-       *imop = imo;
-       imo->imo_multicast_ifp = NULL;
-       imo->imo_multicast_addr.s_addr = INADDR_ANY;
-       imo->imo_multicast_vif = -1;
-       imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
-       imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
-       imo->imo_num_memberships = 0;
-       
-       return 0;
+
+       imo = (how == M_WAITOK) ? zalloc(imo_zone) : zalloc_noblock(imo_zone);
+       if (imo != NULL) {
+               bzero(imo, imo_size);
+               lck_mtx_init(&imo->imo_lock, ifa_mtx_grp, ifa_mtx_attr);
+               imo->imo_debug |= IFD_ALLOC;
+               if (imo_debug != 0) {
+                       imo->imo_debug |= IFD_DEBUG;
+                       imo->imo_trace = imo_trace;
+               }
+               IMO_ADDREF(imo);
+       }
+
+       return (imo);
 }
 
 /*
- * Add membership to an IPv4 multicast.
+ * Routine called from ip_output() to loop back a copy of an IP multicast
+ * packet to the input queue of a specified interface.  Note that this
+ * calls the output routine of the loopback "driver", but with an interface
+ * pointer that might NOT be a loopback interface -- evil, but easier than
+ * replicating that code here.
  */
-__private_extern__ int
-ip_addmembership(
-       struct ip_moptions *imo,
-       struct ip_mreq *mreq)
+static void
+ip_mloopback(struct ifnet *srcifp, struct ifnet *origifp, struct mbuf *m,
+    struct sockaddr_in *dst, int hlen)
 {
-       struct route ro;
-       struct sockaddr_in *dst;
-       struct ifnet *ifp = NULL;
-       int error = 0;
-       int i;
-       
-       if (!IN_MULTICAST(ntohl(mreq->imr_multiaddr.s_addr))) {
-               error = EINVAL;
-               return error;
-       }
+       struct mbuf *copym;
+       struct ip *ip;
+
+       if (lo_ifp == NULL)
+               return;
+
        /*
-        * If no interface address was provided, use the interface of
-        * the route to the given multicast address.
+        * Copy the packet header as it's needed for the checksum
+        * Make sure to deep-copy IP header portion in case the data
+        * is in an mbuf cluster, so that we can safely override the IP
+        * header portion later.
         */
-       if (mreq->imr_interface.s_addr == INADDR_ANY) {
-               bzero((caddr_t)&ro, sizeof(ro));
-               dst = (struct sockaddr_in *)&ro.ro_dst;
-               dst->sin_len = sizeof(*dst);
-               dst->sin_family = AF_INET;
-               dst->sin_addr = mreq->imr_multiaddr;
-               rtalloc(&ro);
-               if (ro.ro_rt != NULL) {
-                       ifp = ro.ro_rt->rt_ifp;
-                       rtfree(ro.ro_rt);
-               }
-               else {
-                       /* If there's no default route, try using loopback */
-                       mreq->imr_interface.s_addr = INADDR_LOOPBACK;
-               }
-       }
-       
-       if (ifp == NULL) {
-               ifp = ip_multicast_if(&mreq->imr_interface, NULL);
-       }
+       copym = m_copym_mode(m, 0, M_COPYALL, M_DONTWAIT, M_COPYM_COPY_HDR);
+       if (copym != NULL && ((copym->m_flags & M_EXT) || copym->m_len < hlen))
+               copym = m_pullup(copym, hlen);
+
+       if (copym == NULL)
+               return;
 
        /*
-        * See if we found an interface, and confirm that it
-        * supports multicast.
+        * We don't bother to fragment if the IP length is greater
+        * than the interface's MTU.  Can this possibly matter?
         */
-       if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
-               error = EADDRNOTAVAIL;
-               return error;
-       }
+       ip = mtod(copym, struct ip *);
+#if BYTE_ORDER != BIG_ENDIAN
+       HTONS(ip->ip_len);
+       HTONS(ip->ip_off);
+#endif
+       ip->ip_sum = 0;
+       ip->ip_sum = ip_cksum_hdr_out(copym, hlen);
+
        /*
-        * See if the membership already exists or if all the
-        * membership slots are full.
+        * Mark checksum as valid unless receive checksum offload is
+        * disabled; if so, compute checksum in software.  If the
+        * interface itself is lo0, this will be overridden by if_loop.
         */
-       for (i = 0; i < imo->imo_num_memberships; ++i) {
-               if (imo->imo_membership[i]->inm_ifp == ifp &&
-                       imo->imo_membership[i]->inm_addr.s_addr
-                                       == mreq->imr_multiaddr.s_addr)
-                       break;
-       }
-       if (i < imo->imo_num_memberships) {
-               error = EADDRINUSE;
-               return error;
-       }
-       if (i == IP_MAX_MEMBERSHIPS) {
-               error = ETOOMANYREFS;
-               return error;
+       if (hwcksum_rx) {
+               copym->m_pkthdr.csum_flags &= ~(CSUM_PARTIAL|CSUM_ZERO_INVERT);
+               copym->m_pkthdr.csum_flags |=
+                   CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
+               copym->m_pkthdr.csum_data = 0xffff;
+       } else if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
+#if BYTE_ORDER != BIG_ENDIAN
+               NTOHS(ip->ip_len);
+#endif
+               in_delayed_cksum(copym);
+#if BYTE_ORDER != BIG_ENDIAN
+               HTONS(ip->ip_len);
+#endif
        }
+
        /*
-        * Everything looks good; add a new record to the multicast
-        * address list for the given interface.
+        * Stuff the 'real' ifp into the pkthdr, to be used in matching
+        * in ip_input(); we need the loopback ifp/dl_tag passed as args
+        * to make the loopback driver compliant with the data link
+        * requirements.
         */
-       if ((imo->imo_membership[i] =
-               in_addmulti(&mreq->imr_multiaddr, ifp)) == NULL) {
-               error = ENOBUFS;
-               return error;
-       }
-       ++imo->imo_num_memberships;
-       
-       return error;
+       copym->m_pkthdr.rcvif = origifp;
+
+       /*
+        * Also record the source interface (which owns the source address).
+        * This is basically a stripped down version of ifa_foraddr().
+        */
+       if (srcifp == NULL) {
+               struct in_ifaddr *ia;
+
+               lck_rw_lock_shared(in_ifaddr_rwlock);
+               TAILQ_FOREACH(ia, INADDR_HASH(ip->ip_src.s_addr), ia_hash) {
+                       IFA_LOCK_SPIN(&ia->ia_ifa);
+                       if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_src.s_addr) {
+                               srcifp = ia->ia_ifp;
+                               IFA_UNLOCK(&ia->ia_ifa);
+                               break;
+                       }
+                       IFA_UNLOCK(&ia->ia_ifa);
+               }
+               lck_rw_done(in_ifaddr_rwlock);
+       }
+       if (srcifp != NULL)
+               ip_setsrcifaddr_info(copym, srcifp->if_index, NULL);
+       ip_setdstifaddr_info(copym, origifp->if_index, NULL);
+
+       dlil_output(lo_ifp, PF_INET, copym, NULL, SA(dst), 0, NULL);
 }
 
 /*
- * Drop membership of an IPv4 multicast.
+ * Given a source IP address (and route, if available), determine the best
+ * interface to send the packet from.  Checking for (and updating) the
+ * ROF_SRCIF_SELECTED flag in the pcb-supplied route placeholder is done
+ * without any locks based on the assumption that ip_output() is single-
+ * threaded per-pcb, i.e. for any given pcb there can only be one thread
+ * performing output at the IP layer.
+ *
+ * This routine is analogous to in6_selectroute() for IPv6.
  */
-__private_extern__ int
-ip_dropmembership(
-       struct ip_moptions *imo,
-       struct ip_mreq *mreq)
+static struct ifaddr *
+in_selectsrcif(struct ip *ip, struct route *ro, unsigned int ifscope)
 {
-       int error = 0;
-       struct ifnet* ifp = NULL;
-       int i;
-       
-       if (!IN_MULTICAST(ntohl(mreq->imr_multiaddr.s_addr))) {
-               error = EINVAL;
-               return error;
+       struct ifaddr *ifa = NULL;
+       struct in_addr src = ip->ip_src;
+       struct in_addr dst = ip->ip_dst;
+       struct ifnet *rt_ifp;
+       char s_src[MAX_IPv4_STR_LEN], s_dst[MAX_IPv4_STR_LEN];
+
+       VERIFY(src.s_addr != INADDR_ANY);
+
+       if (ip_select_srcif_debug) {
+               (void) inet_ntop(AF_INET, &src.s_addr, s_src, sizeof (s_src));
+               (void) inet_ntop(AF_INET, &dst.s_addr, s_dst, sizeof (s_dst));
        }
 
+       if (ro->ro_rt != NULL)
+               RT_LOCK(ro->ro_rt);
+
+       rt_ifp = (ro->ro_rt != NULL) ? ro->ro_rt->rt_ifp : NULL;
+
        /*
-        * If an interface address was specified, get a pointer
-        * to its ifnet structure.
+        * Given the source IP address, find a suitable source interface
+        * to use for transmission; if the caller has specified a scope,
+        * optimize the search by looking at the addresses only for that
+        * interface.  This is still suboptimal, however, as we need to
+        * traverse the per-interface list.
         */
-       if (mreq->imr_interface.s_addr == INADDR_ANY)
-               ifp = NULL;
-       else {
-               ifp = ip_multicast_if(&mreq->imr_interface, NULL);
-               if (ifp == NULL) {
-                       error = EADDRNOTAVAIL;
-                       return error;
+       if (ifscope != IFSCOPE_NONE || ro->ro_rt != NULL) {
+               unsigned int scope = ifscope;
+
+               /*
+                * If no scope is specified and the route is stale (pointing
+                * to a defunct interface) use the current primary interface;
+                * this happens when switching between interfaces configured
+                * with the same IP address.  Otherwise pick up the scope
+                * information from the route; the ULP may have looked up a
+                * correct route and we just need to verify it here and mark
+                * it with the ROF_SRCIF_SELECTED flag below.
+                */
+               if (scope == IFSCOPE_NONE) {
+                       scope = rt_ifp->if_index;
+                       if (scope != get_primary_ifscope(AF_INET) &&
+                           ROUTE_UNUSABLE(ro))
+                               scope = get_primary_ifscope(AF_INET);
+               }
+
+               ifa = (struct ifaddr *)ifa_foraddr_scoped(src.s_addr, scope);
+
+               if (ifa == NULL && ip->ip_p != IPPROTO_UDP &&
+                   ip->ip_p != IPPROTO_TCP && ipforwarding) {
+                       /*
+                        * If forwarding is enabled, and if the packet isn't
+                        * TCP or UDP, check if the source address belongs
+                        * to one of our own interfaces; if so, demote the
+                        * interface scope and do a route lookup right below.
+                        */
+                       ifa = (struct ifaddr *)ifa_foraddr(src.s_addr);
+                       if (ifa != NULL) {
+                               IFA_REMREF(ifa);
+                               ifa = NULL;
+                               ifscope = IFSCOPE_NONE;
+                       }
+               }
+
+               if (ip_select_srcif_debug && ifa != NULL) {
+                       if (ro->ro_rt != NULL) {
+                               printf("%s->%s ifscope %d->%d ifa_if %s "
+                                   "ro_if %s\n", s_src, s_dst, ifscope,
+                                   scope, if_name(ifa->ifa_ifp),
+                                   if_name(rt_ifp));
+                       } else {
+                               printf("%s->%s ifscope %d->%d ifa_if %s\n",
+                                   s_src, s_dst, ifscope, scope,
+                                   if_name(ifa->ifa_ifp));
+                       }
                }
        }
+
        /*
-        * Find the membership in the membership array.
+        * Slow path; search for an interface having the corresponding source
+        * IP address if the scope was not specified by the caller, and:
+        *
+        *   1) There currently isn't any route, or,
+        *   2) The interface used by the route does not own that source
+        *      IP address; in this case, the route will get blown away
+        *      and we'll do a more specific scoped search using the newly
+        *      found interface.
         */
-       for (i = 0; i < imo->imo_num_memberships; ++i) {
-               if ((ifp == NULL ||
-                        imo->imo_membership[i]->inm_ifp == ifp) &&
-                        imo->imo_membership[i]->inm_addr.s_addr ==
-                        mreq->imr_multiaddr.s_addr)
-                       break;
-       }
-       if (i == imo->imo_num_memberships) {
-               error = EADDRNOTAVAIL;
-               return error;
+       if (ifa == NULL && ifscope == IFSCOPE_NONE) {
+               ifa = (struct ifaddr *)ifa_foraddr(src.s_addr);
+
+               /*
+                * If we have the IP address, but not the route, we don't
+                * really know whether or not it belongs to the correct
+                * interface (it could be shared across multiple interfaces.)
+                * The only way to find out is to do a route lookup.
+                */
+               if (ifa != NULL && ro->ro_rt == NULL) {
+                       struct rtentry *rt;
+                       struct sockaddr_in sin;
+                       struct ifaddr *oifa = NULL;
+
+                       bzero(&sin, sizeof (sin));
+                       sin.sin_family = AF_INET;
+                       sin.sin_len = sizeof (sin);
+                       sin.sin_addr = dst;
+
+                       lck_mtx_lock(rnh_lock);
+                       if ((rt = rt_lookup(TRUE, SA(&sin), NULL,
+                           rt_tables[AF_INET], IFSCOPE_NONE)) != NULL) {
+                               RT_LOCK(rt);
+                               /*
+                                * If the route uses a different interface,
+                                * use that one instead.  The IP address of
+                                * the ifaddr that we pick up here is not
+                                * relevant.
+                                */
+                               if (ifa->ifa_ifp != rt->rt_ifp) {
+                                       oifa = ifa;
+                                       ifa = rt->rt_ifa;
+                                       IFA_ADDREF(ifa);
+                                       RT_UNLOCK(rt);
+                               } else {
+                                       RT_UNLOCK(rt);
+                               }
+                               rtfree_locked(rt);
+                       }
+                       lck_mtx_unlock(rnh_lock);
+
+                       if (oifa != NULL) {
+                               struct ifaddr *iifa;
+
+                               /*
+                                * See if the interface pointed to by the
+                                * route is configured with the source IP
+                                * address of the packet.
+                                */
+                               iifa = (struct ifaddr *)ifa_foraddr_scoped(
+                                   src.s_addr, ifa->ifa_ifp->if_index);
+
+                               if (iifa != NULL) {
+                                       /*
+                                        * Found it; drop the original one
+                                        * as well as the route interface
+                                        * address, and use this instead.
+                                        */
+                                       IFA_REMREF(oifa);
+                                       IFA_REMREF(ifa);
+                                       ifa = iifa;
+                               } else if (!ipforwarding ||
+                                   (rt->rt_flags & RTF_GATEWAY)) {
+                                       /*
+                                        * This interface doesn't have that
+                                        * source IP address; drop the route
+                                        * interface address and just use the
+                                        * original one, and let the caller
+                                        * do a scoped route lookup.
+                                        */
+                                       IFA_REMREF(ifa);
+                                       ifa = oifa;
+                               } else {
+                                       /*
+                                        * Forwarding is enabled and the source
+                                        * address belongs to one of our own
+                                        * interfaces which isn't the outgoing
+                                        * interface, and we have a route, and
+                                        * the destination is on a network that
+                                        * is directly attached (onlink); drop
+                                        * the original one and use the route
+                                        * interface address instead.
+                                        */
+                                       IFA_REMREF(oifa);
+                               }
+                       }
+               } else if (ifa != NULL && ro->ro_rt != NULL &&
+                   !(ro->ro_rt->rt_flags & RTF_GATEWAY) &&
+                   ifa->ifa_ifp != ro->ro_rt->rt_ifp && ipforwarding) {
+                       /*
+                        * Forwarding is enabled and the source address belongs
+                        * to one of our own interfaces which isn't the same
+                        * as the interface used by the known route; drop the
+                        * original one and use the route interface address.
+                        */
+                       IFA_REMREF(ifa);
+                       ifa = ro->ro_rt->rt_ifa;
+                       IFA_ADDREF(ifa);
+               }
+
+               if (ip_select_srcif_debug && ifa != NULL) {
+                       printf("%s->%s ifscope %d ifa_if %s\n",
+                           s_src, s_dst, ifscope, if_name(ifa->ifa_ifp));
+               }
        }
+
+       if (ro->ro_rt != NULL)
+               RT_LOCK_ASSERT_HELD(ro->ro_rt);
        /*
-        * Give up the multicast address record to which the
-        * membership points.
+        * If there is a non-loopback route with the wrong interface, or if
+        * there is no interface configured with such an address, blow it
+        * away.  Except for local/loopback, we look for one with a matching
+        * interface scope/index.
         */
-       in_delmulti(&imo->imo_membership[i]);
+       if (ro->ro_rt != NULL &&
+           (ifa == NULL || (ifa->ifa_ifp != rt_ifp && rt_ifp != lo_ifp) ||
+           !(ro->ro_rt->rt_flags & RTF_UP))) {
+               if (ip_select_srcif_debug) {
+                       if (ifa != NULL) {
+                               printf("%s->%s ifscope %d ro_if %s != "
+                                   "ifa_if %s (cached route cleared)\n",
+                                   s_src, s_dst, ifscope, if_name(rt_ifp),
+                                   if_name(ifa->ifa_ifp));
+                       } else {
+                               printf("%s->%s ifscope %d ro_if %s "
+                                   "(no ifa_if found)\n",
+                                   s_src, s_dst, ifscope, if_name(rt_ifp));
+                       }
+               }
+
+               RT_UNLOCK(ro->ro_rt);
+               ROUTE_RELEASE(ro);
+
+               /*
+                * If the destination is IPv4 LLA and the route's interface
+                * doesn't match the source interface, then the source IP
+                * address is wrong; it most likely belongs to the primary
+                * interface associated with the IPv4 LL subnet.  Drop the
+                * packet rather than letting it go out and return an error
+                * to the ULP.  This actually applies not only to IPv4 LL
+                * but other shared subnets; for now we explicitly test only
+                * for the former case and save the latter for future.
+                */
+               if (IN_LINKLOCAL(ntohl(dst.s_addr)) &&
+                   !IN_LINKLOCAL(ntohl(src.s_addr)) && ifa != NULL) {
+                       IFA_REMREF(ifa);
+                       ifa = NULL;
+               }
+       }
+
+       if (ip_select_srcif_debug && ifa == NULL) {
+               printf("%s->%s ifscope %d (neither ro_if/ifa_if found)\n",
+                   s_src, s_dst, ifscope);
+       }
+
        /*
-        * Remove the gap in the membership array.
+        * If there is a route, mark it accordingly.  If there isn't one,
+        * we'll get here again during the next transmit (possibly with a
+        * route) and the flag will get set at that point.  For IPv4 LLA
+        * destination, mark it only if the route has been fully resolved;
+        * otherwise we want to come back here again when the route points
+        * to the interface over which the ARP reply arrives on.
         */
-       for (++i; i < imo->imo_num_memberships; ++i)
-               imo->imo_membership[i-1] = imo->imo_membership[i];
-       --imo->imo_num_memberships;
-       
-       return error;
+       if (ro->ro_rt != NULL && (!IN_LINKLOCAL(ntohl(dst.s_addr)) ||
+           (ro->ro_rt->rt_gateway->sa_family == AF_LINK &&
+           SDL(ro->ro_rt->rt_gateway)->sdl_alen != 0))) {
+               if (ifa != NULL)
+                       IFA_ADDREF(ifa);        /* for route */
+               if (ro->ro_srcia != NULL)
+                       IFA_REMREF(ro->ro_srcia);
+               ro->ro_srcia = ifa;
+               ro->ro_flags |= ROF_SRCIF_SELECTED;
+               RT_GENID_SYNC(ro->ro_rt);
+       }
+
+       if (ro->ro_rt != NULL)
+               RT_UNLOCK(ro->ro_rt);
+
+       return (ifa);
 }
 
-/*
- * Return the IP multicast options in response to user getsockopt().
- */
-static int
-ip_getmoptions(sopt, imo)
-       struct sockopt *sopt;
-       register struct ip_moptions *imo;
+void
+ip_output_checksum(struct ifnet *ifp, struct mbuf *m, int hlen, int ip_len,
+    uint32_t *sw_csum)
 {
-       struct in_addr addr;
-       struct in_ifaddr *ia;
-       int error, optval;
-       u_char coptval;
+       int tso = TSO_IPV4_OK(ifp, m);
+       uint32_t hwcap = ifp->if_hwassist;
 
-       error = 0;
-       switch (sopt->sopt_name) {
-       case IP_MULTICAST_VIF: 
-               if (imo != NULL)
-                       optval = imo->imo_multicast_vif;
-               else
-                       optval = -1;
-               error = sooptcopyout(sopt, &optval, sizeof optval);
-               break;
+       m->m_pkthdr.csum_flags |= CSUM_IP;
+
+       if (!hwcksum_tx) {
+               /* do all in software; hardware checksum offload is disabled */
+               *sw_csum = (CSUM_DELAY_DATA | CSUM_DELAY_IP) &
+                   m->m_pkthdr.csum_flags;
+       } else {
+               /* do in software what the hardware cannot */
+               *sw_csum = m->m_pkthdr.csum_flags &
+                   ~IF_HWASSIST_CSUM_FLAGS(hwcap);
+       }
 
-       case IP_MULTICAST_IF:
-               if (imo == NULL || imo->imo_multicast_ifp == NULL)
-                       addr.s_addr = INADDR_ANY;
-               else if (imo->imo_multicast_addr.s_addr) {
-                       /* return the value user has set */
-                       addr = imo->imo_multicast_addr;
+       if (hlen != sizeof (struct ip)) {
+               *sw_csum |= ((CSUM_DELAY_DATA | CSUM_DELAY_IP) &
+                   m->m_pkthdr.csum_flags);
+       } else if (!(*sw_csum & CSUM_DELAY_DATA) && (hwcap & CSUM_PARTIAL)) {
+               /*
+                * Partial checksum offload, if non-IP fragment, and TCP only
+                * (no UDP support, as the hardware may not be able to convert
+                * +0 to -0 (0xffff) per RFC1122 4.1.3.4. unless the interface
+                * supports "invert zero" capability.)
+                */
+               if (hwcksum_tx && !tso &&
+                   ((m->m_pkthdr.csum_flags & CSUM_TCP) ||
+                   ((hwcap & CSUM_ZERO_INVERT) &&
+                   (m->m_pkthdr.csum_flags & CSUM_ZERO_INVERT))) &&
+                   ip_len <= ifp->if_mtu) {
+                       uint16_t start = sizeof (struct ip);
+                       uint16_t ulpoff = m->m_pkthdr.csum_data & 0xffff;
+                       m->m_pkthdr.csum_flags |=
+                           (CSUM_DATA_VALID | CSUM_PARTIAL);
+                       m->m_pkthdr.csum_tx_stuff = (ulpoff + start);
+                       m->m_pkthdr.csum_tx_start = start;
+                       /* do IP hdr chksum in software */
+                       *sw_csum = CSUM_DELAY_IP;
                } else {
-                       IFP_TO_IA(imo->imo_multicast_ifp, ia);
-                       addr.s_addr = (ia == NULL) ? INADDR_ANY
-                               : IA_SIN(ia)->sin_addr.s_addr;
+                       *sw_csum |= (CSUM_DELAY_DATA & m->m_pkthdr.csum_flags);
                }
-               error = sooptcopyout(sopt, &addr, sizeof addr);
-               break;
-
-       case IP_MULTICAST_TTL:
-               if (imo == 0)
-                       optval = coptval = IP_DEFAULT_MULTICAST_TTL;
-               else
-                       optval = coptval = imo->imo_multicast_ttl;
-               if (sopt->sopt_valsize == 1)
-                       error = sooptcopyout(sopt, &coptval, 1);
-               else
-                       error = sooptcopyout(sopt, &optval, sizeof optval);
-               break;
-
-       case IP_MULTICAST_LOOP:
-               if (imo == 0)
-                       optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
-               else
-                       optval = coptval = imo->imo_multicast_loop;
-               if (sopt->sopt_valsize == 1)
-                       error = sooptcopyout(sopt, &coptval, 1);
-               else
-                       error = sooptcopyout(sopt, &optval, sizeof optval);
-               break;
-
-       default:
-               error = ENOPROTOOPT;
-               break;
        }
-       return (error);
-}
 
-/*
- * Discard the IP multicast options.
- */
-void
-ip_freemoptions(imo)
-       register struct ip_moptions *imo;
-{
-       register int i;
+       if (*sw_csum & CSUM_DELAY_DATA) {
+               in_delayed_cksum(m);
+               *sw_csum &= ~CSUM_DELAY_DATA;
+       }
 
-       if (imo != NULL) {
-               for (i = 0; i < imo->imo_num_memberships; ++i)
-                       in_delmulti(&imo->imo_membership[i]);
-               FREE(imo, M_IPMOPTS);
+       if (hwcksum_tx) {
+               /*
+                * Drop off bits that aren't supported by hardware;
+                * also make sure to preserve non-checksum related bits.
+                */
+               m->m_pkthdr.csum_flags =
+                   ((m->m_pkthdr.csum_flags &
+                   (IF_HWASSIST_CSUM_FLAGS(hwcap) | CSUM_DATA_VALID)) |
+                   (m->m_pkthdr.csum_flags & ~IF_HWASSIST_CSUM_MASK));
+       } else {
+               /* drop all bits; hardware checksum offload is disabled */
+               m->m_pkthdr.csum_flags = 0;
        }
 }
 
 /*
- * Routine called from ip_output() to loop back a copy of an IP multicast
- * packet to the input queue of a specified interface.  Note that this
- * calls the output routine of the loopback "driver", but with an interface
- * pointer that might NOT be a loopback interface -- evil, but easier than
- * replicating that code here.
+ * GRE protocol output for PPP/PPTP
  */
-static void
-ip_mloopback(ifp, m, dst, hlen)
-       struct ifnet *ifp;
-       register struct mbuf *m;
-       register struct sockaddr_in *dst;
-       int hlen;
+int
+ip_gre_output(struct mbuf *m)
 {
-       register struct ip *ip;
-       struct mbuf *copym;
+       struct route ro;
+       int error;
 
-       copym = m_copy(m, 0, M_COPYALL);
-       if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
-               copym = m_pullup(copym, hlen);
-       if (copym != NULL) {
-               /*
-                * We don't bother to fragment if the IP length is greater
-                * than the interface's MTU.  Can this possibly matter?
-                */
-               ip = mtod(copym, struct ip *);
-               HTONS(ip->ip_len);
-               HTONS(ip->ip_off);
-               ip->ip_sum = 0;
-               ip->ip_sum = in_cksum(copym, hlen);
-               /*
-                * NB:
-                * It's not clear whether there are any lingering
-                * reentrancy problems in other areas which might
-                * be exposed by using ip_input directly (in
-                * particular, everything which modifies the packet
-                * in-place).  Yet another option is using the
-                * protosw directly to deliver the looped back
-                * packet.  For the moment, we'll err on the side
-                * of safety by using if_simloop().
-                */
-#if 1 /* XXX */
-               if (dst->sin_family != AF_INET) {
-                       printf("ip_mloopback: bad address family %d\n",
-                                               dst->sin_family);
-                       dst->sin_family = AF_INET;
-               }
-#endif
+       bzero(&ro, sizeof (ro));
 
+       error = ip_output(m, NULL, &ro, 0, NULL, NULL);
 
-        /*
-        * Mark checksum as valid or calculate checksum for loopback.
-        * 
-        * This is done this way because we have to embed the ifp of
-        * the interface we will send the original copy of the packet
-        * out on in the mbuf. ip_input will check if_hwassist of the
-        * embedded ifp and ignore all csum_flags if if_hwassist is 0.
-        * The UDP checksum has not been calculated yet.
-        */
-        if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
-            if (IF_HWASSIST_CSUM_FLAGS(ifp->if_hwassist)) {
-                copym->m_pkthdr.csum_flags |=
-                    CSUM_DATA_VALID | CSUM_PSEUDO_HDR |
-                    CSUM_IP_CHECKED | CSUM_IP_VALID;
-                copym->m_pkthdr.csum_data = 0xffff;
-            } else {
-               NTOHS(ip->ip_len);
-                in_delayed_cksum(copym);
-               HTONS(ip->ip_len);
-           }
-        }
+       ROUTE_RELEASE(&ro);
 
+       return (error);
+}
 
-               /*
-                * TedW: 
-                * We need to send all loopback traffic down to dlil in case 
-                * a filter has tapped-in.
-                */
+static int
+sysctl_reset_ip_output_stats SYSCTL_HANDLER_ARGS
+{
+#pragma unused(arg1, arg2)
+       int error, i;
 
-               /*
-                * Stuff the 'real' ifp into the pkthdr, to be used in matching
-                *  in ip_input(); we need the loopback ifp/dl_tag passed as args
-                *  to make the loopback driver compliant with the data link
-                *  requirements.
-                */
-               if (lo_ifp) {
-                       copym->m_pkthdr.rcvif = ifp;
-                   dlil_output(lo_ifp, PF_INET, copym, 0, (struct sockaddr *) dst, 0);
-               } else {
-                   printf("Warning: ip_output call to dlil_find_dltag failed!\n");
-                   m_freem(copym);
-               }
+       i = ip_output_measure;
+       error = sysctl_handle_int(oidp, &i, 0, req);
+       if (error || req->newptr == USER_ADDR_NULL)
+               goto done;
+       /* impose bounds */
+       if (i < 0 || i > 1) {
+               error = EINVAL;
+               goto done;
+       }
+       if (ip_output_measure != i && i == 1) {
+               net_perf_initialize(&net_perf, ip_output_measure_bins);
+       }
+       ip_output_measure = i;
+done:
+       return (error);
+}
 
-/*             if_simloop(ifp, copym, (struct sockaddr *)dst, 0);*/
+static int
+sysctl_ip_output_measure_bins SYSCTL_HANDLER_ARGS
+{
+#pragma unused(arg1, arg2)
+       int error;
+       uint64_t i;
+
+       i = ip_output_measure_bins;
+       error = sysctl_handle_quad(oidp, &i, 0, req);
+       if (error || req->newptr == USER_ADDR_NULL)
+               goto done;
+       /* validate data */
+       if (!net_perf_validate_bins(i)) {
+               error = EINVAL;
+               goto done;
        }
+       ip_output_measure_bins = i;
+done:
+       return (error);
+}
+
+static int
+sysctl_ip_output_getperf SYSCTL_HANDLER_ARGS
+{
+#pragma unused(oidp, arg1, arg2)
+       if (req->oldptr == USER_ADDR_NULL)
+               req->oldlen = (size_t)sizeof (struct ipstat);
+
+       return (SYSCTL_OUT(req, &net_perf, MIN(sizeof (net_perf), req->oldlen)));
 }