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xnu-3789.70.16.tar.gz
[apple/xnu.git] / bsd / netinet / tcp_subr.c
index 2fa47c3effb16f2b70da2763bc62af41c33c9e84..b2e18eb0580b8632b03669ccd2736db044d30d92 100644 (file)
@@ -1,15 +1,20 @@
 /*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2016 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
- * @APPLE_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. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- * 
+ * 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,
@@ -17,8 +22,8 @@
  * 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_LICENSE_HEADER_END@
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
  * SUCH DAMAGE.
  *
  *     @(#)tcp_subr.c  8.2 (Berkeley) 5/24/95
- * $FreeBSD: src/sys/netinet/tcp_subr.c,v 1.73.2.22 2001/08/22 00:59:12 silby 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.
+ */
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -64,9 +73,7 @@
 #include <sys/sysctl.h>
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
-#if INET6
 #include <sys/domain.h>
-#endif
 #include <sys/proc.h>
 #include <sys/kauth.h>
 #include <sys/socket.h>
 #include <sys/protosw.h>
 #include <sys/random.h>
 #include <sys/syslog.h>
+#include <sys/mcache.h>
 #include <kern/locks.h>
+#include <kern/zalloc.h>
 
-
+#include <dev/random/randomdev.h>
 
 #include <net/route.h>
 #include <net/if.h>
+#include <net/content_filter.h>
 
-#define _IP_VHL
+#define        tcp_minmssoverload fring
+#define        _IP_VHL
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
 #if INET6
 #include <netinet/ip6.h>
 #endif
 #endif
 #include <netinet/in_var.h>
 #include <netinet/ip_var.h>
+#include <netinet/icmp_var.h>
 #if INET6
 #include <netinet6/ip6_var.h>
 #endif
 #include <netinet/tcp_seq.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
+#include <netinet/tcp_cc.h>
+#include <netinet/tcp_cache.h>
+#include <kern/thread_call.h>
+
 #if INET6
 #include <netinet6/tcp6_var.h>
 #endif
 #if INET6
 #include <netinet6/ipsec6.h>
 #endif
-#endif /*IPSEC*/
+#endif /* IPSEC */
+
+#if NECP
+#include <net/necp.h>
+#endif /* NECP */
 
-#include <sys/md5.h>
+#undef tcp_minmssoverload
+
+#if CONFIG_MACF_NET
+#include <security/mac_framework.h>
+#endif /* MAC_NET */
+
+#include <corecrypto/ccaes.h>
+#include <libkern/crypto/aes.h>
+#include <libkern/crypto/md5.h>
 #include <sys/kdebug.h>
+#include <mach/sdt.h>
 
-#define DBG_FNC_TCP_CLOSE      NETDBG_CODE(DBG_NETTCP, ((5 << 8) | 2))
+#include <netinet/lro_ext.h>
+
+#define        DBG_FNC_TCP_CLOSE       NETDBG_CODE(DBG_NETTCP, ((5 << 8) | 2))
 
 extern int tcp_lq_overflow;
 
-/* temporary: for testing */
-#if IPSEC
-extern int ipsec_bypass;
-extern lck_mtx_t *sadb_mutex;
-#endif
+extern struct tcptimerlist tcp_timer_list;
+extern struct tcptailq tcp_tw_tailq;
 
 int    tcp_mssdflt = TCP_MSS;
-SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW
-    &tcp_mssdflt , 0, "Default TCP Maximum Segment Size");
+SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_mssdflt, 0, "Default TCP Maximum Segment Size");
 
 #if INET6
 int    tcp_v6mssdflt = TCP6_MSS;
 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
-       CTLFLAG_RW, &tcp_v6mssdflt , 0,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_v6mssdflt, 0,
        "Default TCP Maximum Segment Size for IPv6");
 #endif
 
+extern int tcp_do_autorcvbuf;
+
+int tcp_sysctl_fastopenkey(struct sysctl_oid *, void *, int,
+    struct sysctl_req *);
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, fastopen_key, CTLTYPE_STRING | CTLFLAG_WR,
+       0, 0, tcp_sysctl_fastopenkey, "S", "TCP Fastopen key");
+
+/* Current count of half-open TFO connections */
+int    tcp_tfo_halfcnt = 0;
+
+/* Maximum of half-open TFO connection backlog */
+int    tcp_tfo_backlog = 10;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, fastopen_backlog,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_tfo_backlog, 0,
+       "Backlog queue for half-open TFO connections");
+
+int    tcp_fastopen = TCP_FASTOPEN_CLIENT | TCP_FASTOPEN_SERVER;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, fastopen, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_fastopen, 0, "Enable TCP Fastopen (RFC 7413)");
+
+int    tcp_tfo_fallback_min = 10;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, fastopen_fallback_min,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_tfo_fallback_min, 0,
+       "Mininum number of trials without TFO when in fallback mode");
+
 /*
  * Minimum MSS we accept and use. This prevents DoS attacks where
  * we are forced to a ridiculous low MSS like 20 and send hundreds
@@ -151,60 +205,84 @@ SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
  * checking. This setting prevents us from sending too small packets.
  */
 int    tcp_minmss = TCP_MINMSS;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
-    &tcp_minmss , 0, "Minmum TCP Maximum Segment Size");
-
-/*
- * Number of TCP segments per second we accept from remote host
- * before we start to calculate average segment size. If average
- * segment size drops below the minimum TCP MSS we assume a DoS
- * attack and reset+drop the connection. Care has to be taken not to
- * set this value too small to not kill interactive type connections
- * (telnet, SSH) which send many small packets.
- */
-#ifdef FIX_WORKAROUND_FOR_3894301
-__private_extern__ int     tcp_minmssoverload = TCP_MINMSSOVERLOAD;
-#else
-__private_extern__ int     tcp_minmssoverload = 0;
-#endif
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW,
-    &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to"
-    "be under the MINMSS Size");
-
-static int     tcp_do_rfc1323 = 1;
-SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 
-    &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions");
-
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_minmss, 0, "Minmum TCP Maximum Segment Size");
+int tcp_do_rfc1323 = 1;
+#if (DEVELOPMENT || DEBUG)
+SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_do_rfc1323, 0,
+       "Enable rfc1323 (high performance TCP) extensions");
+#endif /* (DEVELOPMENT || DEBUG) */
+
+// Not used
 static int     tcp_do_rfc1644 = 0;
-SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 
-    &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions");
-
-static int     tcp_tcbhashsize = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
-     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
+SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_do_rfc1644, 0,
+       "Enable rfc1644 (TTCP) extensions");
 
 static int     do_tcpdrain = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
-     "Enable tcp_drain routine for extra help when low on mbufs");
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &do_tcpdrain, 0,
+       "Enable tcp_drain routine for extra help when low on mbufs");
+
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD | CTLFLAG_LOCKED,
+       &tcbinfo.ipi_count, 0, "Number of active PCBs");
 
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 
-    &tcbinfo.ipi_count, 0, "Number of active PCBs");
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, tw_pcbcount, CTLFLAG_RD | CTLFLAG_LOCKED,
+       &tcbinfo.ipi_twcount, 0, "Number of pcbs in time-wait state");
 
 static int     icmp_may_rst = 1;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 
-    "Certain ICMP unreachable messages may abort connections in SYN_SENT");
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &icmp_may_rst, 0,
+       "Certain ICMP unreachable messages may abort connections in SYN_SENT");
 
 static int     tcp_strict_rfc1948 = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, strict_rfc1948, CTLFLAG_RW,
-    &tcp_strict_rfc1948, 0, "Determines if RFC1948 is followed exactly");
-
 static int     tcp_isn_reseed_interval = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
-    &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
+#if (DEVELOPMENT || DEBUG)
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, strict_rfc1948, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_strict_rfc1948, 0, "Determines if RFC1948 is followed exactly");
+
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval,
+       CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
+#endif /* (DEVELOPMENT || DEBUG) */
+
+int    tcp_TCPTV_MIN = 100;    /* 100ms minimum RTT */
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, rtt_min, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_TCPTV_MIN, 0, "min rtt value allowed");
+
+int tcp_rexmt_slop = TCPTV_REXMTSLOP;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmt_slop, CTLFLAG_RW,
+       &tcp_rexmt_slop, 0, "Slop added to retransmit timeout");
+
+__private_extern__ int tcp_use_randomport = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, randomize_ports,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_use_randomport, 0,
+       "Randomize TCP port numbers");
+
+__private_extern__ int tcp_win_scale = 3;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, win_scale_factor,
+       CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_win_scale, 0,
+       "Window scaling factor");
 
 static void    tcp_cleartaocache(void);
 static void    tcp_notify(struct inpcb *, int);
 
+struct zone    *sack_hole_zone;
+struct zone    *tcp_reass_zone;
+struct zone    *tcp_bwmeas_zone;
+struct zone    *tcp_rxt_seg_zone;
+
+extern int slowlink_wsize;     /* window correction for slow links */
+extern int path_mtu_discovery;
+
+static void tcp_sbrcv_grow_rwin(struct tcpcb *tp, struct sockbuf *sb);
+
+#define        TCP_BWMEAS_BURST_MINSIZE 6
+#define        TCP_BWMEAS_BURST_MAXSIZE 25
+
+static uint32_t bwmeas_elm_size;
+
 /*
  * Target size of TCP PCB hash tables. Must be a power of two.
  *
@@ -212,9 +290,13 @@ static void        tcp_notify(struct inpcb *, int);
  * variable net.inet.tcp.tcbhashsize
  */
 #ifndef TCBHASHSIZE
-#define TCBHASHSIZE    4096
+#define        TCBHASHSIZE     CONFIG_TCBHASHSIZE
 #endif
 
+__private_extern__ int tcp_tcbhashsize = TCBHASHSIZE;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD | CTLFLAG_LOCKED,
+       &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
+
 /*
  * This is the actual shape of what we allocate using the zone
  * allocator.  Doing it this way allows us to protect both structures
@@ -224,141 +306,346 @@ static void     tcp_notify(struct inpcb *, int);
  * to be changed, eventually, for greater efficiency).
  */
 #define        ALIGNMENT       32
-#define        ALIGNM1         (ALIGNMENT - 1)
 struct inp_tp {
-       union {
-               struct  inpcb inp;
-               char    align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1];
-       } inp_tp_u;
-       struct  tcpcb tcb;
-#ifndef __APPLE__
-       struct  callout inp_tp_rexmt, inp_tp_persist, inp_tp_keep, inp_tp_2msl;
-       struct  callout inp_tp_delack;
-#endif
+       struct  inpcb   inp;
+       struct  tcpcb   tcb __attribute__((aligned(ALIGNMENT)));
 };
 #undef ALIGNMENT
-#undef ALIGNM1
 
-static struct tcpcb dummy_tcb;
+int  get_inpcb_str_size(void);
+int  get_tcp_str_size(void);
+
+static void tcpcb_to_otcpcb(struct tcpcb *, struct otcpcb *);
+
+static lck_attr_t *tcp_uptime_mtx_attr = NULL;
+static lck_grp_t *tcp_uptime_mtx_grp = NULL;
+static lck_grp_attr_t *tcp_uptime_mtx_grp_attr = NULL;
+int tcp_notsent_lowat_check(struct socket *so);
+
+static aes_encrypt_ctx tfo_ctx; /* Crypto-context for TFO */
 
+void
+tcp_tfo_gen_cookie(struct inpcb *inp, u_char *out, size_t blk_size)
+{
+       u_char in[CCAES_BLOCK_SIZE];
+#if INET6
+       int isipv6 = inp->inp_vflag & INP_IPV6;
+#endif
 
-extern struct  inpcbhead       time_wait_slots[];
-extern int             cur_tw_slot;
-extern u_long          *delack_bitmask;
-extern u_long  route_generation;
+       VERIFY(blk_size == CCAES_BLOCK_SIZE);
+
+       bzero(&in[0], CCAES_BLOCK_SIZE);
+       bzero(&out[0], CCAES_BLOCK_SIZE);
+
+#if INET6
+       if (isipv6)
+               memcpy(in, &inp->in6p_faddr, sizeof(struct in6_addr));
+       else
+#endif /* INET6 */
+               memcpy(in, &inp->inp_faddr, sizeof(struct in_addr));
 
+       aes_encrypt_cbc(in, NULL, 1, out, &tfo_ctx);
+}
 
-int  get_inpcb_str_size()
+__private_extern__ int
+tcp_sysctl_fastopenkey(__unused struct sysctl_oid *oidp, __unused void *arg1,
+    __unused int arg2, struct sysctl_req *req)
 {
-       return sizeof(struct inpcb);
+       int error = 0;
+       /*
+        * TFO-key is expressed as a string in hex format
+        * (+1 to account for \0 char)
+        */
+       char keystring[TCP_FASTOPEN_KEYLEN * 2 + 1];
+       u_int32_t key[TCP_FASTOPEN_KEYLEN / sizeof(u_int32_t)];
+       int i;
+
+       /* -1, because newlen is len without the terminating \0 character */
+       if (req->newlen != (sizeof(keystring) - 1)) {
+               error = EINVAL;
+               goto exit;
+       }
+
+       /*
+        * sysctl_io_string copies keystring into the oldptr of the sysctl_req.
+        * Make sure everything is zero, to avoid putting garbage in there or
+        * leaking the stack.
+        */
+       bzero(keystring, sizeof(keystring));
+
+       error = sysctl_io_string(req, keystring, sizeof(keystring), 0, NULL);
+       if (error)
+               goto exit;
+
+       for (i = 0; i < (TCP_FASTOPEN_KEYLEN / sizeof(u_int32_t)); i++) {
+               /*
+                * We jump over the keystring in 8-character (4 byte in hex)
+                * steps
+                */
+               if (sscanf(&keystring[i * 8], "%8x", &key[i]) != 1) {
+                       error = EINVAL;
+                       goto exit;
+               }
+       }
+
+       aes_encrypt_key128((u_char *)key, &tfo_ctx);
+
+exit:
+       return (error);
 }
 
+int
+get_inpcb_str_size(void)
+{
+       return (sizeof(struct inpcb));
+}
 
-int  get_tcp_str_size()
+int
+get_tcp_str_size(void)
 {
-       return sizeof(struct tcpcb);
+       return (sizeof(struct tcpcb));
 }
 
 int    tcp_freeq(struct tcpcb *tp);
 
+static int scale_to_powerof2(int size);
+
+/*
+ * This helper routine returns one of the following scaled value of size:
+ * 1. Rounded down power of two value of size if the size value passed as
+ *    argument is not a power of two and the rounded up value overflows.
+ * OR
+ * 2. Rounded up power of two value of size if the size value passed as
+ *    argument is not a power of two and the rounded up value does not overflow
+ * OR
+ * 3. Same value as argument size if it is already a power of two.
+ */
+static int
+scale_to_powerof2(int size) {
+       /* Handle special case of size = 0 */
+       int ret = size ? size : 1;
+
+       if (!powerof2(ret)) {
+               while (!powerof2(size)) {
+                       /*
+                        * Clear out least significant
+                        * set bit till size is left with
+                        * its highest set bit at which point
+                        * it is rounded down power of two.
+                        */
+                       size = size & (size -1);
+               }
+
+               /* Check for overflow when rounding up */
+               if (0 == (size << 1)) {
+                       ret = size;
+               } else {
+                       ret = size << 1;
+               }
+       }
+
+       return (ret);
+}
+
+static void
+tcp_tfo_init(void)
+{
+       u_char key[TCP_FASTOPEN_KEYLEN];
+
+       read_random(key, sizeof(key));
+       aes_encrypt_key128(key, &tfo_ctx);
+}
 
 /*
  * Tcp initialization
  */
 void
-tcp_init()
+tcp_init(struct protosw *pp, struct domain *dp)
 {
-       int hashsize = TCBHASHSIZE;
-       vm_size_t       str_size;
-       int i;
-       struct inpcbinfo *pcbinfo;
-       
+#pragma unused(dp)
+       static int tcp_initialized = 0;
+       vm_size_t str_size;
+       struct inpcbinfo *pcbinfo;
+
+       VERIFY((pp->pr_flags & (PR_INITIALIZED|PR_ATTACHED)) == PR_ATTACHED);
+
+       if (tcp_initialized)
+               return;
+       tcp_initialized = 1;
+
        tcp_ccgen = 1;
        tcp_cleartaocache();
 
-       tcp_delacktime = TCPTV_DELACK;
        tcp_keepinit = TCPTV_KEEP_INIT;
        tcp_keepidle = TCPTV_KEEP_IDLE;
        tcp_keepintvl = TCPTV_KEEPINTVL;
+       tcp_keepcnt = TCPTV_KEEPCNT;
        tcp_maxpersistidle = TCPTV_KEEP_IDLE;
        tcp_msl = TCPTV_MSL;
+
+       microuptime(&tcp_uptime);
        read_random(&tcp_now, sizeof(tcp_now));
-       tcp_now  = tcp_now & 0x7fffffff; /* Starts tcp internal 500ms clock at a random value */
 
+       /* Starts tcp internal clock at a random value */
+       tcp_now = tcp_now & 0x3fffffff;
+
+       tcp_tfo_init();
 
        LIST_INIT(&tcb);
-       tcbinfo.listhead = &tcb;
+       tcbinfo.ipi_listhead = &tcb;
+
        pcbinfo = &tcbinfo;
-#ifndef __APPLE__
-       TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
-#endif
-       if (!powerof2(hashsize)) {
-               printf("WARNING: TCB hash size not a power of 2\n");
-               hashsize = 512; /* safe default */
-       }
-       tcp_tcbhashsize = hashsize;
-       tcbinfo.hashsize = hashsize;
-       tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask);
-       tcbinfo.porthashbase = hashinit(hashsize, M_PCB,
-                                       &tcbinfo.porthashmask);
-#ifdef __APPLE__
-       str_size = (vm_size_t) sizeof(struct inp_tp);
-       tcbinfo.ipi_zone = (void *) zinit(str_size, 120000*str_size, 8192, "tcpcb");
-#else
-       tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
-                                ZONE_INTERRUPT, 0);
-#endif
+       /*
+        * allocate lock group attribute and group for tcp pcb mutexes
+        */
+       pcbinfo->ipi_lock_grp_attr = lck_grp_attr_alloc_init();
+       pcbinfo->ipi_lock_grp = lck_grp_alloc_init("tcppcb",
+           pcbinfo->ipi_lock_grp_attr);
 
-       tcp_reass_maxseg = nmbclusters / 16;
-#ifndef __APPLE__
-       TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
-           &tcp_reass_maxseg);
-#endif
+       /*
+        * allocate the lock attribute for tcp pcb mutexes
+        */
+       pcbinfo->ipi_lock_attr = lck_attr_alloc_init();
+
+       if ((pcbinfo->ipi_lock = lck_rw_alloc_init(pcbinfo->ipi_lock_grp,
+           pcbinfo->ipi_lock_attr)) == NULL) {
+               panic("%s: unable to allocate PCB lock\n", __func__);
+               /* NOTREACHED */
+       }
+
+       if (tcp_tcbhashsize == 0) {
+               /* Set to default */
+               tcp_tcbhashsize = 512;
+       }
+
+       if (!powerof2(tcp_tcbhashsize)) {
+               int old_hash_size = tcp_tcbhashsize;
+               tcp_tcbhashsize = scale_to_powerof2(tcp_tcbhashsize);
+               /* Lower limit of 16  */
+               if (tcp_tcbhashsize < 16) {
+                       tcp_tcbhashsize = 16;
+               }
+               printf("WARNING: TCB hash size not a power of 2, "
+                               "scaled from %d to %d.\n",
+                               old_hash_size,
+                               tcp_tcbhashsize);
+       }
+
+       tcbinfo.ipi_hashbase = hashinit(tcp_tcbhashsize, M_PCB,
+           &tcbinfo.ipi_hashmask);
+       tcbinfo.ipi_porthashbase = hashinit(tcp_tcbhashsize, M_PCB,
+                                       &tcbinfo.ipi_porthashmask);
+       str_size = P2ROUNDUP(sizeof(struct inp_tp), sizeof(u_int64_t));
+       tcbinfo.ipi_zone = zinit(str_size, 120000*str_size, 8192, "tcpcb");
+       zone_change(tcbinfo.ipi_zone, Z_CALLERACCT, FALSE);
+       zone_change(tcbinfo.ipi_zone, Z_EXPAND, TRUE);
+
+       tcbinfo.ipi_gc = tcp_gc;
+       tcbinfo.ipi_timer = tcp_itimer;
+       in_pcbinfo_attach(&tcbinfo);
+
+       str_size = P2ROUNDUP(sizeof(struct sackhole), sizeof(u_int64_t));
+       sack_hole_zone = zinit(str_size, 120000*str_size, 8192,
+           "sack_hole zone");
+       zone_change(sack_hole_zone, Z_CALLERACCT, FALSE);
+       zone_change(sack_hole_zone, Z_EXPAND, TRUE);
+
+       str_size = P2ROUNDUP(sizeof(struct tseg_qent), sizeof(u_int64_t));
+       tcp_reass_zone = zinit(str_size, (nmbclusters >> 4) * str_size,
+               0, "tcp_reass_zone");
+       if (tcp_reass_zone == NULL) {
+               panic("%s: failed allocating tcp_reass_zone", __func__);
+               /* NOTREACHED */
+       }
+       zone_change(tcp_reass_zone, Z_CALLERACCT, FALSE);
+       zone_change(tcp_reass_zone, Z_EXPAND, TRUE);
+
+       bwmeas_elm_size = P2ROUNDUP(sizeof(struct bwmeas), sizeof(u_int64_t));
+       tcp_bwmeas_zone = zinit(bwmeas_elm_size, (100 * bwmeas_elm_size), 0,
+           "tcp_bwmeas_zone");
+       if (tcp_bwmeas_zone == NULL) {
+               panic("%s: failed allocating tcp_bwmeas_zone", __func__);
+               /* NOTREACHED */
+       }
+       zone_change(tcp_bwmeas_zone, Z_CALLERACCT, FALSE);
+       zone_change(tcp_bwmeas_zone, Z_EXPAND, TRUE);
+
+       str_size = P2ROUNDUP(sizeof(struct tcp_ccstate), sizeof(u_int64_t));
+       tcp_cc_zone = zinit(str_size, 20000 * str_size, 0, "tcp_cc_zone");
+       zone_change(tcp_cc_zone, Z_CALLERACCT, FALSE);
+       zone_change(tcp_cc_zone, Z_EXPAND, TRUE);
+
+       str_size = P2ROUNDUP(sizeof(struct tcp_rxt_seg), sizeof(u_int64_t));
+       tcp_rxt_seg_zone = zinit(str_size, 10000 * str_size, 0,
+           "tcp_rxt_seg_zone");
+       zone_change(tcp_rxt_seg_zone, Z_CALLERACCT, FALSE);
+       zone_change(tcp_rxt_seg_zone, Z_EXPAND, TRUE);
 
 #if INET6
-#define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
+#define        TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
 #else /* INET6 */
-#define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
+#define        TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
 #endif /* INET6 */
-       if (max_protohdr < TCP_MINPROTOHDR)
-               max_protohdr = TCP_MINPROTOHDR;
-       if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
+       if (max_protohdr < TCP_MINPROTOHDR) {
+               _max_protohdr = TCP_MINPROTOHDR;
+               _max_protohdr = max_protohdr;   /* round it up */
+       }
+       if (max_linkhdr + max_protohdr > MCLBYTES)
                panic("tcp_init");
 #undef TCP_MINPROTOHDR
-       dummy_tcb.t_state = TCP_NSTATES;
-       dummy_tcb.t_flags = 0;
-       tcbinfo.dummy_cb = (caddr_t) &dummy_tcb;
 
-        /*
-        * allocate lock group attribute and group for tcp pcb mutexes
-        */
-     pcbinfo->mtx_grp_attr = lck_grp_attr_alloc_init();
-       lck_grp_attr_setdefault(pcbinfo->mtx_grp_attr);
-       pcbinfo->mtx_grp = lck_grp_alloc_init("tcppcb", pcbinfo->mtx_grp_attr);
-               
+       /* Initialize time wait and timer lists */
+       TAILQ_INIT(&tcp_tw_tailq);
+
+       bzero(&tcp_timer_list, sizeof(tcp_timer_list));
+       LIST_INIT(&tcp_timer_list.lhead);
        /*
-        * allocate the lock attribute for tcp pcb mutexes
+        * allocate lock group attribute, group and attribute for
+        * the tcp timer list
         */
-       pcbinfo->mtx_attr = lck_attr_alloc_init();
-       lck_attr_setdefault(pcbinfo->mtx_attr);
-
-       if ((pcbinfo->mtx = lck_rw_alloc_init(pcbinfo->mtx_grp, pcbinfo->mtx_attr)) == NULL) {
-               printf("tcp_init: mutex not alloced!\n");
-               return; /* pretty much dead if this fails... */
+       tcp_timer_list.mtx_grp_attr = lck_grp_attr_alloc_init();
+       tcp_timer_list.mtx_grp = lck_grp_alloc_init("tcptimerlist",
+           tcp_timer_list.mtx_grp_attr);
+       tcp_timer_list.mtx_attr = lck_attr_alloc_init();
+       if ((tcp_timer_list.mtx = lck_mtx_alloc_init(tcp_timer_list.mtx_grp,
+           tcp_timer_list.mtx_attr)) == NULL) {
+               panic("failed to allocate memory for tcp_timer_list.mtx\n");
+       };
+       tcp_timer_list.call = thread_call_allocate(tcp_run_timerlist, NULL);
+       if (tcp_timer_list.call == NULL) {
+               panic("failed to allocate call entry 1 in tcp_init\n");
        }
 
+       /*
+        * allocate lock group attribute, group and attribute for
+        * tcp_uptime_lock
+        */
+       tcp_uptime_mtx_grp_attr = lck_grp_attr_alloc_init();
+       tcp_uptime_mtx_grp = lck_grp_alloc_init("tcpuptime",
+           tcp_uptime_mtx_grp_attr);
+       tcp_uptime_mtx_attr = lck_attr_alloc_init();
+       tcp_uptime_lock = lck_spin_alloc_init(tcp_uptime_mtx_grp,
+           tcp_uptime_mtx_attr);
 
-       in_pcb_nat_init(&tcbinfo, AF_INET, IPPROTO_TCP, SOCK_STREAM);
+       /* Initialize TCP LRO data structures */
+       tcp_lro_init();
 
-       delack_bitmask = _MALLOC((4 * hashsize)/32, M_PCB, M_WAITOK);
-       if (delack_bitmask == 0) 
-            panic("Delack Memory");
+       /* Initialize TCP Cache */
+       tcp_cache_init();
 
-       for (i=0; i < (tcbinfo.hashsize / 32); i++)
-                delack_bitmask[i] = 0;
+       /*
+        * If more than 60 MB of mbuf pool is available, increase the
+        * maximum allowed receive and send socket buffer size.
+        */
+       if (nmbclusters > 30720) {
+               tcp_autorcvbuf_max = 1024 * 1024;
+               tcp_autosndbuf_max = 1024 * 1024;
 
-       for (i=0; i < N_TIME_WAIT_SLOTS; i++) {
-            LIST_INIT(&time_wait_slots[i]);
+               /*
+                * Receive buffer max for cellular interfaces supporting
+                * Carrier Aggregation is higher
+                */
+               tcp_autorcvbuf_max_ca = 2 * 1024 * 1024;
        }
 }
 
@@ -368,10 +655,7 @@ tcp_init()
  * of the tcpcb each time to conserve mbufs.
  */
 void
-tcp_fillheaders(tp, ip_ptr, tcp_ptr)
-       struct tcpcb *tp;
-       void *ip_ptr;
-       void *tcp_ptr;
+tcp_fillheaders(struct tcpcb *tp, void *ip_ptr, void *tcp_ptr)
 {
        struct inpcb *inp = tp->t_inpcb;
        struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr;
@@ -382,31 +666,34 @@ tcp_fillheaders(tp, ip_ptr, tcp_ptr)
 
                ip6 = (struct ip6_hdr *)ip_ptr;
                ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
-                       (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
+                       (inp->inp_flow & IPV6_FLOWINFO_MASK);
                ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
                        (IPV6_VERSION & IPV6_VERSION_MASK);
+               ip6->ip6_plen = htons(sizeof(struct tcphdr));
                ip6->ip6_nxt = IPPROTO_TCP;
-               ip6->ip6_plen = sizeof(struct tcphdr);
+               ip6->ip6_hlim = 0;
                ip6->ip6_src = inp->in6p_laddr;
                ip6->ip6_dst = inp->in6p_faddr;
-               tcp_hdr->th_sum = 0;
+               tcp_hdr->th_sum = in6_pseudo(&inp->in6p_laddr, &inp->in6p_faddr,
+                   htonl(sizeof (struct tcphdr) + IPPROTO_TCP));
        } else
 #endif
        {
-       struct ip *ip = (struct ip *) ip_ptr;
-
-       ip->ip_vhl = IP_VHL_BORING;
-       ip->ip_tos = 0;
-       ip->ip_len = 0;
-       ip->ip_id = 0;
-       ip->ip_off = 0;
-       ip->ip_ttl = 0;
-       ip->ip_sum = 0;
-       ip->ip_p = IPPROTO_TCP;
-       ip->ip_src = inp->inp_laddr;
-       ip->ip_dst = inp->inp_faddr;
-       tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
-               htons(sizeof(struct tcphdr) + IPPROTO_TCP));
+               struct ip *ip = (struct ip *) ip_ptr;
+
+               ip->ip_vhl = IP_VHL_BORING;
+               ip->ip_tos = 0;
+               ip->ip_len = 0;
+               ip->ip_id = 0;
+               ip->ip_off = 0;
+               ip->ip_ttl = 0;
+               ip->ip_sum = 0;
+               ip->ip_p = IPPROTO_TCP;
+               ip->ip_src = inp->inp_laddr;
+               ip->ip_dst = inp->inp_faddr;
+               tcp_hdr->th_sum =
+                   in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
+                   htons(sizeof(struct tcphdr) + IPPROTO_TCP));
        }
 
        tcp_hdr->th_sport = inp->inp_lport;
@@ -426,8 +713,7 @@ tcp_fillheaders(tp, ip_ptr, tcp_ptr)
  * use for this function is in keepalives, which use tcp_respond.
  */
 struct tcptemp *
-tcp_maketemplate(tp)
-       struct tcpcb *tp;
+tcp_maketemplate(struct tcpcb *tp)
 {
        struct mbuf *m;
        struct tcptemp *n;
@@ -457,15 +743,10 @@ tcp_maketemplate(tp)
  * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
  */
 void
-tcp_respond(tp, ipgen, th, m, ack, seq, flags)
-       struct tcpcb *tp;
-       void *ipgen;
-       register struct tcphdr *th;
-       register struct mbuf *m;
-       tcp_seq ack, seq;
-       int flags;
+tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
+    tcp_seq ack, tcp_seq seq, int flags, struct tcp_respond_args *tra)
 {
-       register int tlen;
+       int tlen;
        int win = 0;
        struct route *ro = 0;
        struct route sro;
@@ -477,7 +758,8 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
        struct ip6_hdr *ip6;
        int isipv6;
 #endif /* INET6 */
-       int ipflags = 0;
+       struct ifnet *outif;
+       int sotc = SO_TC_UNSPEC;
 
 #if INET6
        isipv6 = IP_VHL_V(((struct ip *)ipgen)->ip_vhl) == 6;
@@ -487,9 +769,9 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
 
        if (tp) {
                if (!(flags & TH_RST)) {
-                       win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
-                       if (win > (long)TCP_MAXWIN << tp->rcv_scale)
-                               win = (long)TCP_MAXWIN << tp->rcv_scale;
+                       win = tcp_sbspace(tp);
+                       if (win > (int32_t)TCP_MAXWIN << tp->rcv_scale)
+                               win = (int32_t)TCP_MAXWIN << tp->rcv_scale;
                }
 #if INET6
                if (isipv6)
@@ -501,34 +783,43 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
 #if INET6
                if (isipv6) {
                        ro6 = &sro6;
-                       bzero(ro6, sizeof *ro6);
+                       bzero(ro6, sizeof(*ro6));
                } else
 #endif /* INET6 */
                {
                        ro = &sro;
-                       bzero(ro, sizeof *ro);
+                       bzero(ro, sizeof(*ro));
                }
        }
        if (m == 0) {
-               m = m_gethdr(M_DONTWAIT, MT_HEADER);
+               m = m_gethdr(M_DONTWAIT, MT_HEADER);    /* MAC-OK */
                if (m == NULL)
                        return;
                tlen = 0;
                m->m_data += max_linkhdr;
 #if INET6
                if (isipv6) {
-                       bcopy((caddr_t)ip6, mtod(m, caddr_t), 
-                             sizeof(struct ip6_hdr));
+                       VERIFY((MHLEN - max_linkhdr) >=
+                           (sizeof (*ip6) + sizeof (*nth)));
+                       bcopy((caddr_t)ip6, mtod(m, caddr_t),
+                           sizeof(struct ip6_hdr));
                        ip6 = mtod(m, struct ip6_hdr *);
-                       nth = (struct tcphdr *)(ip6 + 1);
+                       nth = (struct tcphdr *)(void *)(ip6 + 1);
                } else
 #endif /* INET6 */
                {
+                       VERIFY((MHLEN - max_linkhdr) >=
+                           (sizeof (*ip) + sizeof (*nth)));
                        bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
                        ip = mtod(m, struct ip *);
-                       nth = (struct tcphdr *)(ip + 1);
+                       nth = (struct tcphdr *)(void *)(ip + 1);
                }
                bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
+#if MPTCP
+               if ((tp) && (tp->t_mpflags & TMPF_RESET))
+                       flags = (TH_RST | TH_ACK);
+               else
+#endif
                flags = TH_ACK;
        } else {
                m_freem(m->m_next);
@@ -536,17 +827,21 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
                m->m_data = (caddr_t)ipgen;
                /* m_len is set later */
                tlen = 0;
-#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
+#define        xchg(a, b, type) { type t; t = a; a = b; b = t; }
 #if INET6
                if (isipv6) {
+                       /* Expect 32-bit aligned IP on strict-align platforms */
+                       IP6_HDR_STRICT_ALIGNMENT_CHECK(ip6);
                        xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
-                       nth = (struct tcphdr *)(ip6 + 1);
+                       nth = (struct tcphdr *)(void *)(ip6 + 1);
                } else
 #endif /* INET6 */
-             {
-               xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
-               nth = (struct tcphdr *)(ip + 1);
-             }
+               {
+                       /* Expect 32-bit aligned IP on strict-align platforms */
+                       IP_HDR_STRICT_ALIGNMENT_CHECK(ip);
+                       xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
+                       nth = (struct tcphdr *)(void *)(ip + 1);
+               }
                if (th != nth) {
                        /*
                         * this is usually a case when an extension header
@@ -566,14 +861,30 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
                tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
        } else
 #endif
-      {
-       tlen += sizeof (struct tcpiphdr);
-       ip->ip_len = tlen;
-       ip->ip_ttl = ip_defttl;
-      }
+       {
+               tlen += sizeof (struct tcpiphdr);
+               ip->ip_len = tlen;
+               ip->ip_ttl = ip_defttl;
+       }
        m->m_len = tlen;
        m->m_pkthdr.len = tlen;
        m->m_pkthdr.rcvif = 0;
+#if CONFIG_MACF_NET
+       if (tp != NULL && tp->t_inpcb != NULL) {
+               /*
+                * Packet is associated with a socket, so allow the
+                * label of the response to reflect the socket label.
+                */
+               mac_mbuf_label_associate_inpcb(tp->t_inpcb, m);
+       } else {
+               /*
+                * Packet is not associated with a socket, so possibly
+                * update the label in place.
+                */
+               mac_netinet_tcp_reply(m);
+       }
+#endif
+
        nth->th_seq = htonl(seq);
        nth->th_ack = htonl(ack);
        nth->th_x2 = 0;
@@ -587,13 +898,12 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
 #if INET6
        if (isipv6) {
                nth->th_sum = 0;
-               nth->th_sum = in6_cksum(m, IPPROTO_TCP,
-                                       sizeof(struct ip6_hdr),
-                                       tlen - sizeof(struct ip6_hdr));
+               nth->th_sum = in6_pseudo(&ip6->ip6_src, &ip6->ip6_dst,
+                   htonl((tlen - sizeof (struct ip6_hdr)) + IPPROTO_TCP));
+               m->m_pkthdr.csum_flags = CSUM_TCPIPV6;
+               m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
                ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL,
-                                              ro6 && ro6->ro_rt ?
-                                              ro6->ro_rt->rt_ifp :
-                                              NULL);
+                   ro6 && ro6->ro_rt ? ro6->ro_rt->rt_ifp : NULL);
        } else
 #endif /* INET6 */
        {
@@ -606,26 +916,112 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
        if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
                tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
 #endif
+
+#if NECP
+       necp_mark_packet_from_socket(m, tp ? tp->t_inpcb : NULL, 0, 0);
+#endif /* NECP */
+
 #if IPSEC
-       if (ipsec_bypass == 0 && ipsec_setsocket(m, tp ? tp->t_inpcb->inp_socket : NULL) != 0) {
+       if (tp != NULL && tp->t_inpcb->inp_sp != NULL &&
+               ipsec_setsocket(m, tp ? tp->t_inpcb->inp_socket : NULL) != 0) {
                m_freem(m);
                return;
        }
 #endif
+
+       if (tp != NULL) {
+               u_int32_t svc_flags = 0;
+               if (isipv6) {
+                       svc_flags |= PKT_SCF_IPV6;
+               }
+               sotc = tp->t_inpcb->inp_socket->so_traffic_class;
+               set_packet_service_class(m, tp->t_inpcb->inp_socket,
+                   sotc, svc_flags);
+
+               /* Embed flowhash and flow control flags */
+               m->m_pkthdr.pkt_flowsrc = FLOWSRC_INPCB;
+               m->m_pkthdr.pkt_flowid = tp->t_inpcb->inp_flowhash;
+               m->m_pkthdr.pkt_flags |= PKTF_FLOW_ID | PKTF_FLOW_LOCALSRC;
+#if MPTCP
+               /* Disable flow advisory when using MPTCP. */
+               if (!(tp->t_mpflags & TMPF_MPTCP_TRUE))
+#endif /* MPTCP */
+                       m->m_pkthdr.pkt_flags |= PKTF_FLOW_ADV;
+               m->m_pkthdr.pkt_proto = IPPROTO_TCP;
+       }
+
 #if INET6
        if (isipv6) {
-               (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL, 0);
-               if (ro6 == &sro6 && ro6->ro_rt) {
-                       rtfree(ro6->ro_rt);
-                       ro6->ro_rt = NULL;
+               struct ip6_out_args ip6oa = { tra->ifscope, { 0 },
+                   IP6OAF_SELECT_SRCIF | IP6OAF_BOUND_SRCADDR, 0,
+                   SO_TC_UNSPEC, _NET_SERVICE_TYPE_UNSPEC};
+
+               if (tra->ifscope != IFSCOPE_NONE)
+                       ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
+               if (tra->nocell)
+                       ip6oa.ip6oa_flags |= IP6OAF_NO_CELLULAR;
+               if (tra->noexpensive)
+                       ip6oa.ip6oa_flags |= IP6OAF_NO_EXPENSIVE;
+               if (tra->awdl_unrestricted)
+                       ip6oa.ip6oa_flags |= IP6OAF_AWDL_UNRESTRICTED;
+               if (tra->intcoproc_allowed)
+                       ip6oa.ip6oa_flags |= IP6OAF_INTCOPROC_ALLOWED;
+               ip6oa.ip6oa_sotc = sotc;
+               if (tp != NULL) {
+                       if ((tp->t_inpcb->inp_socket->so_flags1 & SOF1_QOSMARKING_ALLOWED))
+                               ip6oa.ip6oa_flags |= IP6OAF_QOSMARKING_ALLOWED;
+                       ip6oa.ip6oa_netsvctype = tp->t_inpcb->inp_socket->so_netsvctype;
                }
+               (void) ip6_output(m, NULL, ro6, IPV6_OUTARGS, NULL,
+                   NULL, &ip6oa);
+
+               if (tp != NULL && ro6 != NULL && ro6->ro_rt != NULL &&
+                   (outif = ro6->ro_rt->rt_ifp) !=
+                   tp->t_inpcb->in6p_last_outifp)
+                       tp->t_inpcb->in6p_last_outifp = outif;
+
+               if (ro6 == &sro6)
+                       ROUTE_RELEASE(ro6);
        } else
 #endif /* INET6 */
        {
-               (void) ip_output_list(m, 0, NULL, ro, ipflags, NULL);
-               if (ro == &sro && ro->ro_rt) {
-                       rtfree(ro->ro_rt);
-                       ro->ro_rt = NULL;
+               struct ip_out_args ipoa = { tra->ifscope, { 0 },
+                   IPOAF_SELECT_SRCIF | IPOAF_BOUND_SRCADDR, 0,
+                   SO_TC_UNSPEC, _NET_SERVICE_TYPE_UNSPEC };
+
+               if (tra->ifscope != IFSCOPE_NONE)
+                       ipoa.ipoa_flags |= IPOAF_BOUND_IF;
+               if (tra->nocell)
+                       ipoa.ipoa_flags |= IPOAF_NO_CELLULAR;
+               if (tra->noexpensive)
+                       ipoa.ipoa_flags |= IPOAF_NO_EXPENSIVE;
+               if (tra->awdl_unrestricted)
+                       ipoa.ipoa_flags |= IPOAF_AWDL_UNRESTRICTED;
+               ipoa.ipoa_sotc = sotc;
+               if (tp != NULL) {
+                       if ((tp->t_inpcb->inp_socket->so_flags1 & SOF1_QOSMARKING_ALLOWED))
+                               ipoa.ipoa_flags |= IPOAF_QOSMARKING_ALLOWED;
+                       ipoa.ipoa_netsvctype = tp->t_inpcb->inp_socket->so_netsvctype;
+               }
+               if (ro != &sro) {
+                       /* Copy the cached route and take an extra reference */
+                       inp_route_copyout(tp->t_inpcb, &sro);
+               }
+               /*
+                * For consistency, pass a local route copy.
+                */
+               (void) ip_output(m, NULL, &sro, IP_OUTARGS, NULL, &ipoa);
+
+               if (tp != NULL && sro.ro_rt != NULL &&
+                   (outif = sro.ro_rt->rt_ifp) !=
+                   tp->t_inpcb->inp_last_outifp)
+                       tp->t_inpcb->inp_last_outifp = outif;
+
+               if (ro != &sro) {
+                       /* Synchronize cached PCB route */
+                       inp_route_copyin(tp->t_inpcb, &sro);
+               } else {
+                       ROUTE_RELEASE(&sro);
                }
        }
 }
@@ -637,22 +1033,23 @@ tcp_respond(tp, ipgen, th, m, ack, seq, flags)
  * come from the zone allocator set up in tcp_init().
  */
 struct tcpcb *
-tcp_newtcpcb(inp)
-       struct inpcb *inp;
+tcp_newtcpcb(struct inpcb *inp)
 {
        struct inp_tp *it;
-       register struct tcpcb *tp;
-       register struct socket *so = inp->inp_socket;   
+       struct tcpcb *tp;
+       struct socket *so = inp->inp_socket;
 #if INET6
        int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
 #endif /* INET6 */
 
-       if (so->cached_in_sock_layer == 0) {
-            it = (struct inp_tp *)inp;
-            tp = &it->tcb;
+       calculate_tcp_clock();
+
+       if ((so->so_flags1 & SOF1_CACHED_IN_SOCK_LAYER) == 0) {
+           it = (struct inp_tp *)(void *)inp;
+           tp = &it->tcb;
+       } else {
+           tp = (struct tcpcb *)(void *)inp->inp_saved_ppcb;
        }
-       else
-            tp = (struct tcpcb *) inp->inp_saved_ppcb;
 
        bzero((char *) tp, sizeof(struct tcpcb));
        LIST_INIT(&tp->t_segq);
@@ -662,32 +1059,52 @@ tcp_newtcpcb(inp)
 #endif /* INET6 */
                tcp_mssdflt;
 
-#ifndef __APPLE__
-       /* Set up our timeouts. */
-       callout_init(tp->tt_rexmt = &it->inp_tp_rexmt);
-       callout_init(tp->tt_persist = &it->inp_tp_persist);
-       callout_init(tp->tt_keep = &it->inp_tp_keep);
-       callout_init(tp->tt_2msl = &it->inp_tp_2msl);
-       callout_init(tp->tt_delack = &it->inp_tp_delack);
-#endif
-
        if (tcp_do_rfc1323)
                tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
-       if (tcp_do_rfc1644)
-               tp->t_flags |= TF_REQ_CC;
-       tp->t_inpcb = inp;      /* XXX */
+       if (tcp_do_sack)
+               tp->t_flagsext |= TF_SACK_ENABLE;
+
+       TAILQ_INIT(&tp->snd_holes);
+       SLIST_INIT(&tp->t_rxt_segments);
+       SLIST_INIT(&tp->t_notify_ack);
+       tp->t_inpcb = inp;
        /*
         * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
         * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
         * reasonable initial retransmit time.
         */
        tp->t_srtt = TCPTV_SRTTBASE;
-       tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
-       tp->t_rttmin = TCPTV_MIN;
+       tp->t_rttvar =
+           ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
+       tp->t_rttmin = tcp_TCPTV_MIN;
        tp->t_rxtcur = TCPTV_RTOBASE;
-       tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
+
+       if (tcp_use_newreno)
+               /* use newreno by default */
+               tp->tcp_cc_index = TCP_CC_ALGO_NEWRENO_INDEX;
+       else
+               tp->tcp_cc_index = TCP_CC_ALGO_CUBIC_INDEX;
+
+       tcp_cc_allocate_state(tp);
+
+       if (CC_ALGO(tp)->init != NULL)
+               CC_ALGO(tp)->init(tp);
+
+       tp->snd_cwnd = TCP_CC_CWND_INIT_BYTES;
        tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
-        /*
+       tp->snd_ssthresh_prev = TCP_MAXWIN << TCP_MAX_WINSHIFT;
+       tp->t_rcvtime = tcp_now;
+       tp->tentry.timer_start = tcp_now;
+       tp->t_persist_timeout = tcp_max_persist_timeout;
+       tp->t_persist_stop = 0;
+       tp->t_flagsext |= TF_RCVUNACK_WAITSS;
+       tp->t_rexmtthresh = tcprexmtthresh;
+
+       /* Clear time wait tailq entry */
+       tp->t_twentry.tqe_next = NULL;
+       tp->t_twentry.tqe_prev = NULL;
+
+       /*
         * IPv4 TTL initialization is necessary for an IPv6 socket as well,
         * because the socket may be bound to an IPv6 wildcard address,
         * which may match an IPv4-mapped IPv6 address.
@@ -703,25 +1120,16 @@ tcp_newtcpcb(inp)
  * then send a RST to peer.
  */
 struct tcpcb *
-tcp_drop(tp, errno)
-       register struct tcpcb *tp;
-       int errno;
+tcp_drop(struct tcpcb *tp, int errno)
 {
        struct socket *so = tp->t_inpcb->inp_socket;
-
-#ifdef __APPLE__
-       switch (tp->t_state) 
-       {
-       case TCPS_ESTABLISHED:
-       case TCPS_FIN_WAIT_1:
-       case TCPS_CLOSING:
-       case TCPS_CLOSE_WAIT:
-       case TCPS_LAST_ACK:
-            break;
-       }
+#if CONFIG_DTRACE
+       struct inpcb *inp = tp->t_inpcb;
 #endif
-     
+
        if (TCPS_HAVERCVDSYN(tp->t_state)) {
+               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                       struct tcpcb *, tp, int32_t, TCPS_CLOSED);
                tp->t_state = TCPS_CLOSED;
                (void) tcp_output(tp);
                tcpstat.tcps_drops++;
@@ -733,6 +1141,85 @@ tcp_drop(tp, errno)
        return (tcp_close(tp));
 }
 
+void
+tcp_getrt_rtt(struct tcpcb *tp, struct rtentry *rt)
+{
+       u_int32_t rtt = rt->rt_rmx.rmx_rtt;
+       int isnetlocal = (tp->t_flags & TF_LOCAL);
+
+       if (rtt != 0) {
+               /*
+                * XXX the lock bit for RTT indicates that the value
+                * is also a minimum value; this is subject to time.
+                */
+               if (rt->rt_rmx.rmx_locks & RTV_RTT)
+                       tp->t_rttmin = rtt / (RTM_RTTUNIT / TCP_RETRANSHZ);
+               else
+                       tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN :
+                           TCPTV_REXMTMIN;
+               tp->t_srtt =
+                   rtt / (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTT_SCALE));
+               tcpstat.tcps_usedrtt++;
+               if (rt->rt_rmx.rmx_rttvar) {
+                       tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
+                           (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTTVAR_SCALE));
+                       tcpstat.tcps_usedrttvar++;
+               } else {
+                       /* default variation is +- 1 rtt */
+                       tp->t_rttvar =
+                           tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
+               }
+               TCPT_RANGESET(tp->t_rxtcur,
+                       ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
+                       tp->t_rttmin, TCPTV_REXMTMAX,
+                       TCP_ADD_REXMTSLOP(tp));
+       }
+}
+
+static inline void
+tcp_update_ecn_perf_stats(struct tcpcb *tp,
+    struct if_tcp_ecn_perf_stat *stat)
+{
+       u_int64_t curval, oldval;
+       struct inpcb *inp = tp->t_inpcb;
+       stat->total_txpkts += inp->inp_stat->txpackets;
+       stat->total_rxpkts += inp->inp_stat->rxpackets;
+       stat->total_rxmitpkts += tp->t_stat.rxmitpkts;
+       stat->total_oopkts += tp->t_rcvoopack;
+       stat->total_reorderpkts += (tp->t_reordered_pkts + tp->t_pawsdrop +
+           tp->t_dsack_sent + tp->t_dsack_recvd);
+
+       /* Average RTT */
+       curval = (tp->t_srtt >> TCP_RTT_SHIFT);
+       if (curval > 0 && tp->t_rttupdated >= 16) {
+               if (stat->rtt_avg == 0) {
+                       stat->rtt_avg = curval;
+               } else {
+                       oldval = stat->rtt_avg;
+                       stat->rtt_avg =
+                           ((oldval << 4) - oldval + curval) >> 4;
+               }
+       }
+
+       /* RTT variance */
+       curval = tp->t_rttvar >> TCP_RTTVAR_SHIFT;
+       if (curval > 0 && tp->t_rttupdated >= 16) {
+               if (stat->rtt_var == 0) {
+                       stat->rtt_var = curval;
+               } else {
+                       oldval = stat->rtt_var;
+                       stat->rtt_var =
+                           ((oldval << 4) - oldval + curval) >> 4;
+               }
+       }
+
+       /* Total number of SACK recovery episodes */
+       stat->sack_episodes += tp->t_sack_recovery_episode;
+
+       if (inp->inp_socket->so_error == ECONNRESET)
+               stat->rst_drop++;
+}
+
 /*
  * Close a TCP control block:
  *     discard all space held by the tcp
@@ -740,52 +1227,53 @@ tcp_drop(tp, errno)
  *     wake up any sleepers
  */
 struct tcpcb *
-tcp_close(tp)
-       register struct tcpcb *tp;
+tcp_close(struct tcpcb *tp)
 {
-       register struct tseg_qent *q;
        struct inpcb *inp = tp->t_inpcb;
        struct socket *so = inp->inp_socket;
 #if INET6
        int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
 #endif /* INET6 */
-       register struct rtentry *rt;
+       struct route *ro;
+       struct rtentry *rt;
        int dosavessthresh;
 
-       if ( inp->inp_ppcb == NULL) /* tcp_close was called previously, bail */
-               return;
+       /* tcp_close was called previously, bail */
+       if (inp->inp_ppcb == NULL)
+               return (NULL);
+
+       tcp_canceltimers(tp);
+       KERNEL_DEBUG(DBG_FNC_TCP_CLOSE | DBG_FUNC_START, tp, 0, 0, 0, 0);
 
-#ifndef __APPLE__
        /*
-        * Make sure that all of our timers are stopped before we
-        * delete the PCB.
+        * If another thread for this tcp is currently in ip (indicated by
+        * the TF_SENDINPROG flag), defer the cleanup until after it returns
+        * back to tcp.  This is done to serialize the close until after all
+        * pending output is finished, in order to avoid having the PCB be
+        * detached and the cached route cleaned, only for ip to cache the
+        * route back into the PCB again.  Note that we've cleared all the
+        * timers at this point.  Set TF_CLOSING to indicate to tcp_output()
+        * that is should call us again once it returns from ip; at that
+        * point both flags should be cleared and we can proceed further
+        * with the cleanup.
         */
-       callout_stop(tp->tt_rexmt);
-       callout_stop(tp->tt_persist);
-       callout_stop(tp->tt_keep);
-       callout_stop(tp->tt_2msl);
-       callout_stop(tp->tt_delack);
-#else
-       /* Clear the timers before we delete the PCB. */
-       {
-               int i;
-               for (i = 0; i < TCPT_NTIMERS; i++) {
-                       tp->t_timer[i] = 0;
-               }
+       if ((tp->t_flags & TF_CLOSING) ||
+               inp->inp_sndinprog_cnt > 0) {
+               tp->t_flags |= TF_CLOSING;
+               return (NULL);
        }
-#endif
 
-       KERNEL_DEBUG(DBG_FNC_TCP_CLOSE | DBG_FUNC_START, tp,0,0,0,0);
-       switch (tp->t_state) 
-       {
-       case TCPS_ESTABLISHED:
-       case TCPS_FIN_WAIT_1:
-       case TCPS_CLOSING:
-       case TCPS_CLOSE_WAIT:
-       case TCPS_LAST_ACK:
-            break;
-       }
+       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+               struct tcpcb *, tp, int32_t, TCPS_CLOSED);
 
+#if INET6
+       ro = (isipv6 ? (struct route *)&inp->in6p_route : &inp->inp_route);
+#else
+       ro = &inp->inp_route;
+#endif
+       rt = ro->ro_rt;
+       if (rt != NULL)
+               RT_LOCK_SPIN(rt);
 
        /*
         * If we got enough samples through the srtt filter,
@@ -799,32 +1287,33 @@ tcp_close(tp)
         * update anything that the user "locked".
         */
        if (tp->t_rttupdated >= 16) {
-               register u_long i = 0;
+               u_int32_t i = 0;
+
 #if INET6
                if (isipv6) {
                        struct sockaddr_in6 *sin6;
 
-                       if ((rt = inp->in6p_route.ro_rt) == NULL)
+                       if (rt == NULL)
                                goto no_valid_rt;
-                       sin6 = (struct sockaddr_in6 *)rt_key(rt);
+                       sin6 = (struct sockaddr_in6 *)(void *)rt_key(rt);
                        if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
                                goto no_valid_rt;
                }
                else
 #endif /* INET6 */
-               rt = inp->inp_route.ro_rt;      
-               if (rt == NULL ||
-                   ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr
-                   == INADDR_ANY || rt->generation_id != route_generation) {
-                       if (tp->t_state >= TCPS_CLOSE_WAIT)
-                               tp->t_state = TCPS_CLOSING;
-
+               if (ROUTE_UNUSABLE(ro) ||
+                   SIN(rt_key(rt))->sin_addr.s_addr == INADDR_ANY) {
+                       DTRACE_TCP4(state__change, void, NULL,
+                           struct inpcb *, inp, struct tcpcb *, tp,
+                           int32_t, TCPS_CLOSED);
+                       tp->t_state = TCPS_CLOSED;
                        goto no_valid_rt;
                }
 
+               RT_LOCK_ASSERT_HELD(rt);
                if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
                        i = tp->t_srtt *
-                           (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
+                           (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTT_SCALE));
                        if (rt->rt_rmx.rmx_rtt && i)
                                /*
                                 * filter this update to half the old & half
@@ -840,7 +1329,7 @@ tcp_close(tp)
                }
                if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
                        i = tp->t_rttvar *
-                           (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE));
+                           (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTTVAR_SCALE));
                        if (rt->rt_rmx.rmx_rttvar && i)
                                rt->rt_rmx.rmx_rttvar =
                                    (rt->rt_rmx.rmx_rttvar + i) / 2;
@@ -868,8 +1357,8 @@ tcp_close(tp)
                else
                        dosavessthresh = (i < so->so_snd.sb_hiwat / 2);
                if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
-                    i != 0 && rt->rt_rmx.rmx_ssthresh != 0)
-                   || dosavessthresh) {
+                   i != 0 && rt->rt_rmx.rmx_ssthresh != 0) ||
+                   dosavessthresh) {
                        /*
                         * convert the limit from user data bytes to
                         * packets then to packet data bytes.
@@ -877,16 +1366,12 @@ tcp_close(tp)
                        i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
                        if (i < 2)
                                i = 2;
-                       i *= (u_long)(tp->t_maxseg +
-#if INET6
-                                     (isipv6 ? sizeof (struct ip6_hdr) +
-                                              sizeof (struct tcphdr) :
-#endif
-                                      sizeof (struct tcpiphdr)
+                       i *= (u_int32_t)(tp->t_maxseg +
 #if INET6
-                                      )
-#endif
-                                     );
+                           isipv6 ? sizeof (struct ip6_hdr) +
+                           sizeof (struct tcphdr) :
+#endif /* INET6 */
+                           sizeof (struct tcpiphdr));
                        if (rt->rt_rmx.rmx_ssthresh)
                                rt->rt_rmx.rmx_ssthresh =
                                    (rt->rt_rmx.rmx_ssthresh + i) / 2;
@@ -895,93 +1380,254 @@ tcp_close(tp)
                        tcpstat.tcps_cachedssthresh++;
                }
        }
-       rt = inp->inp_route.ro_rt;
-       if (rt) {
-               /* 
-                * mark route for deletion if no information is
-                * cached.
-                */
-               if ((tp->t_flags & TF_LQ_OVERFLOW) && tcp_lq_overflow && 
-                   ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0)){
-                       if (rt->rt_rmx.rmx_rtt == 0)
-                               rt->rt_flags |= RTF_DELCLONE;
+
+       /*
+        * Mark route for deletion if no information is cached.
+        */
+       if (rt != NULL && (so->so_flags & SOF_OVERFLOW) && tcp_lq_overflow) {
+               if (!(rt->rt_rmx.rmx_locks & RTV_RTT) &&
+                   rt->rt_rmx.rmx_rtt == 0) {
+                       rt->rt_flags |= RTF_DELCLONE;
                }
        }
-    no_valid_rt:
+
+no_valid_rt:
+       if (rt != NULL)
+               RT_UNLOCK(rt);
+
        /* free the reassembly queue, if any */
        (void) tcp_freeq(tp);
 
-#ifdef __APPLE__
-       if (so->cached_in_sock_layer)
-           inp->inp_saved_ppcb = (caddr_t) tp;
-#endif
-
-       soisdisconnected(so);
-#if INET6
-       if (INP_CHECK_SOCKAF(so, AF_INET6))
-               in6_pcbdetach(inp);
-       else
-#endif /* INET6 */
-       in_pcbdetach(inp);
-       tcpstat.tcps_closed++;
-       KERNEL_DEBUG(DBG_FNC_TCP_CLOSE | DBG_FUNC_END, tcpstat.tcps_closed,0,0,0,0);
-       return ((struct tcpcb *)0);
+       /* Collect ECN related statistics */
+       if (tp->ecn_flags & TE_SETUPSENT) {
+               if (tp->ecn_flags & TE_CLIENT_SETUP) {
+                       INP_INC_IFNET_STAT(inp, ecn_client_setup);
+                       if (TCP_ECN_ENABLED(tp)) {
+                               INP_INC_IFNET_STAT(inp,
+                                   ecn_client_success);
+                       } else if (tp->ecn_flags & TE_LOST_SYN) {
+                               INP_INC_IFNET_STAT(inp, ecn_syn_lost);
+                       } else {
+                               INP_INC_IFNET_STAT(inp,
+                                   ecn_peer_nosupport);
+                       }
+               } else {
+                       INP_INC_IFNET_STAT(inp, ecn_server_setup);
+                       if (TCP_ECN_ENABLED(tp)) {
+                               INP_INC_IFNET_STAT(inp,
+                                   ecn_server_success);
+                       } else if (tp->ecn_flags & TE_LOST_SYNACK) {
+                               INP_INC_IFNET_STAT(inp,
+                                   ecn_synack_lost);
+                       } else {
+                               INP_INC_IFNET_STAT(inp,
+                                   ecn_peer_nosupport);
+                       }
+               }
+       } else {
+               INP_INC_IFNET_STAT(inp, ecn_off_conn);
+       }
+       if (TCP_ECN_ENABLED(tp)) {
+               if (tp->ecn_flags & TE_RECV_ECN_CE) {
+                       tcpstat.tcps_ecn_conn_recv_ce++;
+                       INP_INC_IFNET_STAT(inp, ecn_conn_recv_ce);
+               }
+               if (tp->ecn_flags & TE_RECV_ECN_ECE) {
+                       tcpstat.tcps_ecn_conn_recv_ece++;
+                       INP_INC_IFNET_STAT(inp, ecn_conn_recv_ece);
+               }
+               if (tp->ecn_flags & (TE_RECV_ECN_CE | TE_RECV_ECN_ECE)) {
+                       if (tp->t_stat.txretransmitbytes > 0 ||
+                           tp->t_stat.rxoutoforderbytes > 0) {
+                               tcpstat.tcps_ecn_conn_pl_ce++;
+                               INP_INC_IFNET_STAT(inp, ecn_conn_plce);
+                       } else {
+                               tcpstat.tcps_ecn_conn_nopl_ce++;
+                               INP_INC_IFNET_STAT(inp, ecn_conn_noplce);
+                       }
+               } else {
+                       if (tp->t_stat.txretransmitbytes > 0 ||
+                           tp->t_stat.rxoutoforderbytes > 0) {
+                               tcpstat.tcps_ecn_conn_plnoce++;
+                               INP_INC_IFNET_STAT(inp, ecn_conn_plnoce);
+                       }
+               }
+       }
+
+       /* Aggregate performance stats */
+       if (inp->inp_last_outifp != NULL && !(tp->t_flags & TF_LOCAL)) {
+               struct ifnet *ifp = inp->inp_last_outifp;
+               ifnet_lock_shared(ifp);
+               if ((ifp->if_refflags & (IFRF_ATTACHED | IFRF_DETACHING)) ==
+                   IFRF_ATTACHED) {
+                       if (inp->inp_vflag & INP_IPV6) {
+                               ifp->if_ipv6_stat->timestamp = net_uptime();
+                               if (TCP_ECN_ENABLED(tp)) {
+                                       tcp_update_ecn_perf_stats(tp,
+                                           &ifp->if_ipv6_stat->ecn_on);
+                               } else {
+                                       tcp_update_ecn_perf_stats(tp,
+                                           &ifp->if_ipv6_stat->ecn_off);
+                               }
+                       } else {
+                               ifp->if_ipv4_stat->timestamp = net_uptime();
+                               if (TCP_ECN_ENABLED(tp)) {
+                                       tcp_update_ecn_perf_stats(tp,
+                                           &ifp->if_ipv4_stat->ecn_on);
+                               } else {
+                                       tcp_update_ecn_perf_stats(tp,
+                                           &ifp->if_ipv4_stat->ecn_off);
+                               }
+                       }
+               }
+               ifnet_lock_done(ifp);
+       }
+
+       tcp_free_sackholes(tp);
+       tcp_notify_ack_free(tp);
+
+       inp_decr_sndbytes_allunsent(so, tp->snd_una);
+
+       if (tp->t_bwmeas != NULL) {
+               tcp_bwmeas_free(tp);
+       }
+       tcp_rxtseg_clean(tp);
+       /* Free the packet list */
+       if (tp->t_pktlist_head != NULL)
+               m_freem_list(tp->t_pktlist_head);
+       TCP_PKTLIST_CLEAR(tp);
+
+#if MPTCP
+       /* Clear MPTCP state */
+       if ((so->so_flags & SOF_MPTCP_TRUE) ||
+           (so->so_flags & SOF_MP_SUBFLOW)) {
+               soevent(so, (SO_FILT_HINT_LOCKED | SO_FILT_HINT_DELETEOK));
+       }
+       tp->t_mpflags = 0;
+       tp->t_mptcb = NULL;
+#endif /* MPTCP */
+
+       if (so->so_flags1 & SOF1_CACHED_IN_SOCK_LAYER)
+           inp->inp_saved_ppcb = (caddr_t) tp;
+
+       tp->t_state = TCPS_CLOSED;
+
+       /*
+        * Issue a wakeup before detach so that we don't miss
+        * a wakeup
+        */
+       sodisconnectwakeup(so);
+
+       /*
+        * Clean up any LRO state
+        */
+       if (tp->t_flagsext & TF_LRO_OFFLOADED) {
+               tcp_lro_remove_state(inp->inp_laddr, inp->inp_faddr,
+                   inp->inp_lport, inp->inp_fport);
+               tp->t_flagsext &= ~TF_LRO_OFFLOADED;
+       }
+
+       /*
+        * If this is a socket that does not want to wakeup the device
+        * for it's traffic, the application might need to know that the
+        * socket is closed, send a notification.
+        */
+       if ((so->so_options & SO_NOWAKEFROMSLEEP) &&
+           inp->inp_state != INPCB_STATE_DEAD &&
+           !(inp->inp_flags2 & INP2_TIMEWAIT))
+               socket_post_kev_msg_closed(so);
+
+       if (CC_ALGO(tp)->cleanup != NULL) {
+               CC_ALGO(tp)->cleanup(tp);
+       }
+
+       if (tp->t_ccstate != NULL) {
+               zfree(tcp_cc_zone, tp->t_ccstate);
+               tp->t_ccstate = NULL;
+       }
+       tp->tcp_cc_index = TCP_CC_ALGO_NONE;
+
+       /* Can happen if we close the socket before receiving the third ACK */
+       if ((tp->t_tfo_flags & TFO_F_COOKIE_VALID)) {
+               OSDecrementAtomic(&tcp_tfo_halfcnt);
+
+               /* Panic if something has gone terribly wrong. */
+               VERIFY(tcp_tfo_halfcnt >= 0);
+
+               tp->t_tfo_flags &= ~TFO_F_COOKIE_VALID;
+       }
+
+#if INET6
+       if (SOCK_CHECK_DOM(so, PF_INET6))
+               in6_pcbdetach(inp);
+       else
+#endif /* INET6 */
+       in_pcbdetach(inp);
+
+       /*
+        * Call soisdisconnected after detach because it might unlock the socket
+        */
+       soisdisconnected(so);
+       tcpstat.tcps_closed++;
+       KERNEL_DEBUG(DBG_FNC_TCP_CLOSE | DBG_FUNC_END,
+           tcpstat.tcps_closed, 0, 0, 0, 0);
+       return (NULL);
 }
 
 int
-tcp_freeq(tp)
-       struct tcpcb *tp;
+tcp_freeq(struct tcpcb *tp)
 {
-
-       register struct tseg_qent *q;
+       struct tseg_qent *q;
        int rv = 0;
 
-       while((q = LIST_FIRST(&tp->t_segq)) != NULL) {
+       while ((q = LIST_FIRST(&tp->t_segq)) != NULL) {
                LIST_REMOVE(q, tqe_q);
                m_freem(q->tqe_m);
-               FREE(q, M_TSEGQ);
-               tcp_reass_qsize--;
+               zfree(tcp_reass_zone, q);
                rv = 1;
        }
+       tp->t_reassqlen = 0;
        return (rv);
 }
 
-void
-tcp_drain()
-{
+
 /*
- * ###LD 05/19/04 locking issue, tcpdrain is disabled, deadlock situation with tcbinfo.mtx
+ * Walk the tcpbs, if existing, and flush the reassembly queue,
+ * if there is one when do_tcpdrain is enabled
+ * Also defunct the extended background idle socket
+ * Do it next time if the pcbinfo lock is in use
  */
-       if (do_tcpdrain)
-       {
-               struct inpcb *inpb;
-               struct tcpcb *tcpb;
-               struct tseg_qent *te;
+void
+tcp_drain(void)
+{
+       struct inpcb *inp;
+       struct tcpcb *tp;
 
-       /*
-        * Walk the tcpbs, if existing, and flush the reassembly queue,
-        * if there is one...
-        * XXX: The "Net/3" implementation doesn't imply that the TCP
-        *      reassembly queue should be flushed, but in a situation
-        *      where we're really low on mbufs, this is potentially
-        *      usefull.        
-        */
-               lck_rw_lock_exclusive(tcbinfo.mtx);
-               for (inpb = LIST_FIRST(tcbinfo.listhead); inpb;
-                       inpb = LIST_NEXT(inpb, inp_list)) {
-                               if ((tcpb = intotcpcb(inpb))) {
-                                       while ((te = LIST_FIRST(&tcpb->t_segq))
-                                              != NULL) {
-                                       LIST_REMOVE(te, tqe_q);
-                                       m_freem(te->tqe_m);
-                                       FREE(te, M_TSEGQ);
-                                       tcp_reass_qsize--;
-                               }
+       if (!lck_rw_try_lock_exclusive(tcbinfo.ipi_lock))
+               return;
+
+       LIST_FOREACH(inp, tcbinfo.ipi_listhead, inp_list) {
+               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) !=
+                       WNT_STOPUSING) {
+                       tcp_lock(inp->inp_socket, 1, 0);
+                       if (in_pcb_checkstate(inp, WNT_RELEASE, 1)
+                               == WNT_STOPUSING) {
+                               /* lost a race, try the next one */
+                               tcp_unlock(inp->inp_socket, 1, 0);
+                               continue;
                        }
-               }
-               lck_rw_done(tcbinfo.mtx);
+                       tp = intotcpcb(inp);
+
+                       if (do_tcpdrain)
+                               tcp_freeq(tp);
 
+                       so_drain_extended_bk_idle(inp->inp_socket);
+
+                       tcp_unlock(inp->inp_socket, 1, 0);
+               }
        }
+       lck_rw_done(tcbinfo.ipi_lock);
+
 }
 
 /*
@@ -993,13 +1639,11 @@ tcp_drain()
  * reporting soft errors (yet - a kqueue filter may be added).
  */
 static void
-tcp_notify(inp, error)
-       struct inpcb *inp;
-       int error;
+tcp_notify(struct inpcb *inp, int error)
 {
        struct tcpcb *tp;
 
-       if (inp == NULL || (inp->inp_state == INPCB_STATE_DEAD)) 
+       if (inp == NULL || (inp->inp_state == INPCB_STATE_DEAD))
                return; /* pcb is gone already */
 
        tp = (struct tcpcb *)inp->inp_ppcb;
@@ -1012,8 +1656,8 @@ tcp_notify(inp, error)
         * can never complete.
         */
        if (tp->t_state == TCPS_ESTABLISHED &&
-            (error == EHOSTUNREACH || error == ENETUNREACH ||
-             error == EHOSTDOWN)) {
+           (error == EHOSTUNREACH || error == ENETUNREACH ||
+           error == EHOSTDOWN)) {
                return;
        } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
            tp->t_softerror)
@@ -1027,11 +1671,126 @@ tcp_notify(inp, error)
 #endif
 }
 
+struct bwmeas *
+tcp_bwmeas_alloc(struct tcpcb *tp)
+{
+       struct bwmeas *elm;
+       elm = zalloc(tcp_bwmeas_zone);
+       if (elm == NULL)
+               return (elm);
+
+       bzero(elm, bwmeas_elm_size);
+       elm->bw_minsizepkts = TCP_BWMEAS_BURST_MINSIZE;
+       elm->bw_maxsizepkts = TCP_BWMEAS_BURST_MAXSIZE;
+       elm->bw_minsize = elm->bw_minsizepkts * tp->t_maxseg;
+       elm->bw_maxsize = elm->bw_maxsizepkts * tp->t_maxseg;
+       return (elm);
+}
+
+void
+tcp_bwmeas_free(struct tcpcb *tp)
+{
+       zfree(tcp_bwmeas_zone, tp->t_bwmeas);
+       tp->t_bwmeas = NULL;
+       tp->t_flagsext &= ~(TF_MEASURESNDBW);
+}
+
+int
+get_tcp_inp_list(struct inpcb **inp_list, int n, inp_gen_t gencnt)
+{
+       struct tcpcb *tp;
+       struct inpcb *inp;
+       int i = 0;
+
+       LIST_FOREACH(inp, tcbinfo.ipi_listhead, inp_list) {
+               if (inp->inp_gencnt <= gencnt &&
+                   inp->inp_state != INPCB_STATE_DEAD)
+                       inp_list[i++] = inp;
+               if (i >= n)
+                       break;
+       }
+
+       TAILQ_FOREACH(tp, &tcp_tw_tailq, t_twentry) {
+               inp = tp->t_inpcb;
+               if (inp->inp_gencnt <= gencnt &&
+                       inp->inp_state != INPCB_STATE_DEAD)
+                       inp_list[i++] = inp;
+               if (i >= n)
+                       break;
+       }
+       return (i);
+}
+
+/*
+ * tcpcb_to_otcpcb copies specific bits of a tcpcb to a otcpcb format.
+ * The otcpcb data structure is passed to user space and must not change.
+ */
+static void
+tcpcb_to_otcpcb(struct tcpcb *tp, struct otcpcb *otp)
+{
+       otp->t_segq = (uint32_t)VM_KERNEL_ADDRPERM(tp->t_segq.lh_first);
+       otp->t_dupacks = tp->t_dupacks;
+       otp->t_timer[TCPT_REXMT_EXT] = tp->t_timer[TCPT_REXMT];
+       otp->t_timer[TCPT_PERSIST_EXT] = tp->t_timer[TCPT_PERSIST];
+       otp->t_timer[TCPT_KEEP_EXT] = tp->t_timer[TCPT_KEEP];
+       otp->t_timer[TCPT_2MSL_EXT] = tp->t_timer[TCPT_2MSL];
+       otp->t_inpcb =
+           (_TCPCB_PTR(struct inpcb *))VM_KERNEL_ADDRPERM(tp->t_inpcb);
+       otp->t_state = tp->t_state;
+       otp->t_flags = tp->t_flags;
+       otp->t_force = (tp->t_flagsext & TF_FORCE) ? 1 : 0;
+       otp->snd_una = tp->snd_una;
+       otp->snd_max = tp->snd_max;
+       otp->snd_nxt = tp->snd_nxt;
+       otp->snd_up = tp->snd_up;
+       otp->snd_wl1 = tp->snd_wl1;
+       otp->snd_wl2 = tp->snd_wl2;
+       otp->iss = tp->iss;
+       otp->irs = tp->irs;
+       otp->rcv_nxt = tp->rcv_nxt;
+       otp->rcv_adv = tp->rcv_adv;
+       otp->rcv_wnd = tp->rcv_wnd;
+       otp->rcv_up = tp->rcv_up;
+       otp->snd_wnd = tp->snd_wnd;
+       otp->snd_cwnd = tp->snd_cwnd;
+       otp->snd_ssthresh = tp->snd_ssthresh;
+       otp->t_maxopd = tp->t_maxopd;
+       otp->t_rcvtime = tp->t_rcvtime;
+       otp->t_starttime = tp->t_starttime;
+       otp->t_rtttime = tp->t_rtttime;
+       otp->t_rtseq = tp->t_rtseq;
+       otp->t_rxtcur = tp->t_rxtcur;
+       otp->t_maxseg = tp->t_maxseg;
+       otp->t_srtt = tp->t_srtt;
+       otp->t_rttvar = tp->t_rttvar;
+       otp->t_rxtshift = tp->t_rxtshift;
+       otp->t_rttmin = tp->t_rttmin;
+       otp->t_rttupdated = tp->t_rttupdated;
+       otp->max_sndwnd = tp->max_sndwnd;
+       otp->t_softerror = tp->t_softerror;
+       otp->t_oobflags = tp->t_oobflags;
+       otp->t_iobc = tp->t_iobc;
+       otp->snd_scale = tp->snd_scale;
+       otp->rcv_scale = tp->rcv_scale;
+       otp->request_r_scale = tp->request_r_scale;
+       otp->requested_s_scale = tp->requested_s_scale;
+       otp->ts_recent = tp->ts_recent;
+       otp->ts_recent_age = tp->ts_recent_age;
+       otp->last_ack_sent = tp->last_ack_sent;
+       otp->cc_send = 0;
+       otp->cc_recv = 0;
+       otp->snd_recover = tp->snd_recover;
+       otp->snd_cwnd_prev = tp->snd_cwnd_prev;
+       otp->snd_ssthresh_prev = tp->snd_ssthresh_prev;
+       otp->t_badrxtwin = 0;
+}
+
 static int
 tcp_pcblist SYSCTL_HANDLER_ARGS
 {
-       int error, i, n, s;
-       struct inpcb *inp, **inp_list;
+#pragma unused(oidp, arg1, arg2)
+       int error, i = 0, n;
+       struct inpcb **inp_list;
        inp_gen_t gencnt;
        struct xinpgen xig;
 
@@ -1039,18 +1798,18 @@ tcp_pcblist SYSCTL_HANDLER_ARGS
         * The process of preparing the TCB list is too time-consuming and
         * resource-intensive to repeat twice on every request.
         */
-       lck_rw_lock_shared(tcbinfo.mtx);
+       lck_rw_lock_shared(tcbinfo.ipi_lock);
        if (req->oldptr == USER_ADDR_NULL) {
                n = tcbinfo.ipi_count;
-               req->oldidx = 2 * (sizeof xig)
+               req->oldidx = 2 * (sizeof(xig))
                        + (n + n/8) * sizeof(struct xtcpcb);
-               lck_rw_done(tcbinfo.mtx);
-               return 0;
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (0);
        }
 
        if (req->newptr != USER_ADDR_NULL) {
-               lck_rw_done(tcbinfo.mtx);
-               return EPERM;
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (EPERM);
        }
 
        /*
@@ -1060,61 +1819,68 @@ tcp_pcblist SYSCTL_HANDLER_ARGS
        n = tcbinfo.ipi_count;
 
        bzero(&xig, sizeof(xig));
-       xig.xig_len = sizeof xig;
+       xig.xig_len = sizeof(xig);
        xig.xig_count = n;
        xig.xig_gen = gencnt;
        xig.xig_sogen = so_gencnt;
-       error = SYSCTL_OUT(req, &xig, sizeof xig);
+       error = SYSCTL_OUT(req, &xig, sizeof(xig));
        if (error) {
-               lck_rw_done(tcbinfo.mtx);
-               return error;
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (error);
        }
-        /*
-         * We are done if there is no pcb
-         */
-        if (n == 0) {
-           lck_rw_done(tcbinfo.mtx);
-            return 0; 
+       /*
+        * We are done if there is no pcb
+        */
+       if (n == 0) {
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (0);
        }
 
-       inp_list = _MALLOC(n * sizeof *inp_list, M_TEMP, M_WAITOK);
+       inp_list = _MALLOC(n * sizeof (*inp_list), M_TEMP, M_WAITOK);
        if (inp_list == 0) {
-               lck_rw_done(tcbinfo.mtx);
-               return ENOMEM;
-       }
-       
-       for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n;
-            inp = LIST_NEXT(inp, inp_list)) {
-#ifdef __APPLE__
-               if (inp->inp_gencnt <= gencnt && inp->inp_state != INPCB_STATE_DEAD)
-#else
-               if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->p, inp))
-#endif
-                       inp_list[i++] = inp;
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (ENOMEM);
        }
-       n = i;
+
+       n = get_tcp_inp_list(inp_list, n, gencnt);
 
        error = 0;
        for (i = 0; i < n; i++) {
+               struct xtcpcb xt;
+               caddr_t inp_ppcb;
+               struct inpcb *inp;
+
                inp = inp_list[i];
-               if (inp->inp_gencnt <= gencnt && inp->inp_state != INPCB_STATE_DEAD) {
-                       struct xtcpcb xt;
-                       caddr_t inp_ppcb;
-
-                       bzero(&xt, sizeof(xt));
-                       xt.xt_len = sizeof xt;
-                       /* XXX should avoid extra copy */
-                       inpcb_to_compat(inp, &xt.xt_inp);
-                       inp_ppcb = inp->inp_ppcb;
-                       if (inp_ppcb != NULL) {
-                               bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
-                       }
-                       else
-                               bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
-                       if (inp->inp_socket)
-                               sotoxsocket(inp->inp_socket, &xt.xt_socket);
-                       error = SYSCTL_OUT(req, &xt, sizeof xt);
+
+               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING)
+                       continue;
+               tcp_lock(inp->inp_socket, 1, NULL);
+               if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
+                       tcp_unlock(inp->inp_socket, 1, NULL);
+                       continue;
+               }
+               if (inp->inp_gencnt > gencnt) {
+                       tcp_unlock(inp->inp_socket, 1, NULL);
+                       continue;
                }
+
+               bzero(&xt, sizeof(xt));
+               xt.xt_len = sizeof(xt);
+               /* XXX should avoid extra copy */
+               inpcb_to_compat(inp, &xt.xt_inp);
+               inp_ppcb = inp->inp_ppcb;
+               if (inp_ppcb != NULL) {
+                       tcpcb_to_otcpcb((struct tcpcb *)(void *)inp_ppcb,
+                           &xt.xt_tp);
+               } else {
+                       bzero((char *) &xt.xt_tp, sizeof(xt.xt_tp));
+               }
+               if (inp->inp_socket)
+                       sotoxsocket(inp->inp_socket, &xt.xt_socket);
+
+               tcp_unlock(inp->inp_socket, 1, NULL);
+
+               error = SYSCTL_OUT(req, &xt, sizeof(xt));
        }
        if (!error) {
                /*
@@ -1125,149 +1891,395 @@ tcp_pcblist SYSCTL_HANDLER_ARGS
                 * might be necessary to retry.
                 */
                bzero(&xig, sizeof(xig));
-               xig.xig_len = sizeof xig;
+               xig.xig_len = sizeof(xig);
                xig.xig_gen = tcbinfo.ipi_gencnt;
                xig.xig_sogen = so_gencnt;
                xig.xig_count = tcbinfo.ipi_count;
-               error = SYSCTL_OUT(req, &xig, sizeof xig);
+               error = SYSCTL_OUT(req, &xig, sizeof(xig));
        }
        FREE(inp_list, M_TEMP);
-       lck_rw_done(tcbinfo.mtx);
-       return error;
+       lck_rw_done(tcbinfo.ipi_lock);
+       return (error);
 }
 
-SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
+SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
+           CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
            tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
 
-#ifndef __APPLE__
+
+static void
+tcpcb_to_xtcpcb64(struct tcpcb *tp, struct xtcpcb64 *otp)
+{
+       otp->t_segq = (uint32_t)VM_KERNEL_ADDRPERM(tp->t_segq.lh_first);
+       otp->t_dupacks = tp->t_dupacks;
+       otp->t_timer[TCPT_REXMT_EXT] = tp->t_timer[TCPT_REXMT];
+       otp->t_timer[TCPT_PERSIST_EXT] = tp->t_timer[TCPT_PERSIST];
+       otp->t_timer[TCPT_KEEP_EXT] = tp->t_timer[TCPT_KEEP];
+       otp->t_timer[TCPT_2MSL_EXT] = tp->t_timer[TCPT_2MSL];
+       otp->t_state = tp->t_state;
+       otp->t_flags = tp->t_flags;
+       otp->t_force = (tp->t_flagsext & TF_FORCE) ? 1 : 0;
+       otp->snd_una = tp->snd_una;
+       otp->snd_max = tp->snd_max;
+       otp->snd_nxt = tp->snd_nxt;
+       otp->snd_up = tp->snd_up;
+       otp->snd_wl1 = tp->snd_wl1;
+       otp->snd_wl2 = tp->snd_wl2;
+       otp->iss = tp->iss;
+       otp->irs = tp->irs;
+       otp->rcv_nxt = tp->rcv_nxt;
+       otp->rcv_adv = tp->rcv_adv;
+       otp->rcv_wnd = tp->rcv_wnd;
+       otp->rcv_up = tp->rcv_up;
+       otp->snd_wnd = tp->snd_wnd;
+       otp->snd_cwnd = tp->snd_cwnd;
+       otp->snd_ssthresh = tp->snd_ssthresh;
+       otp->t_maxopd = tp->t_maxopd;
+       otp->t_rcvtime = tp->t_rcvtime;
+       otp->t_starttime = tp->t_starttime;
+       otp->t_rtttime = tp->t_rtttime;
+       otp->t_rtseq = tp->t_rtseq;
+       otp->t_rxtcur = tp->t_rxtcur;
+       otp->t_maxseg = tp->t_maxseg;
+       otp->t_srtt = tp->t_srtt;
+       otp->t_rttvar = tp->t_rttvar;
+       otp->t_rxtshift = tp->t_rxtshift;
+       otp->t_rttmin = tp->t_rttmin;
+       otp->t_rttupdated = tp->t_rttupdated;
+       otp->max_sndwnd = tp->max_sndwnd;
+       otp->t_softerror = tp->t_softerror;
+       otp->t_oobflags = tp->t_oobflags;
+       otp->t_iobc = tp->t_iobc;
+       otp->snd_scale = tp->snd_scale;
+       otp->rcv_scale = tp->rcv_scale;
+       otp->request_r_scale = tp->request_r_scale;
+       otp->requested_s_scale = tp->requested_s_scale;
+       otp->ts_recent = tp->ts_recent;
+       otp->ts_recent_age = tp->ts_recent_age;
+       otp->last_ack_sent = tp->last_ack_sent;
+       otp->cc_send = 0;
+       otp->cc_recv = 0;
+       otp->snd_recover = tp->snd_recover;
+       otp->snd_cwnd_prev = tp->snd_cwnd_prev;
+       otp->snd_ssthresh_prev = tp->snd_ssthresh_prev;
+       otp->t_badrxtwin = 0;
+}
+
+
 static int
-tcp_getcred(SYSCTL_HANDLER_ARGS)
+tcp_pcblist64 SYSCTL_HANDLER_ARGS
 {
-       struct sockaddr_in addrs[2];
-       struct inpcb *inp;
-       int error, s;
+#pragma unused(oidp, arg1, arg2)
+       int error, i = 0, n;
+       struct inpcb **inp_list;
+       inp_gen_t gencnt;
+       struct xinpgen xig;
 
-       error = suser(req->p);
-       if (error)
-               return (error);
-       error = SYSCTL_IN(req, addrs, sizeof(addrs));
-       if (error)
+       /*
+        * The process of preparing the TCB list is too time-consuming and
+        * resource-intensive to repeat twice on every request.
+        */
+       lck_rw_lock_shared(tcbinfo.ipi_lock);
+       if (req->oldptr == USER_ADDR_NULL) {
+               n = tcbinfo.ipi_count;
+               req->oldidx = 2 * (sizeof(xig))
+                       + (n + n/8) * sizeof(struct xtcpcb64);
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (0);
+       }
+
+       if (req->newptr != USER_ADDR_NULL) {
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (EPERM);
+       }
+
+       /*
+        * OK, now we're committed to doing something.
+        */
+       gencnt = tcbinfo.ipi_gencnt;
+       n = tcbinfo.ipi_count;
+
+       bzero(&xig, sizeof(xig));
+       xig.xig_len = sizeof(xig);
+       xig.xig_count = n;
+       xig.xig_gen = gencnt;
+       xig.xig_sogen = so_gencnt;
+       error = SYSCTL_OUT(req, &xig, sizeof(xig));
+       if (error) {
+               lck_rw_done(tcbinfo.ipi_lock);
                return (error);
-       s = splnet();
-       inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
-           addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
-       if (inp == NULL || inp->inp_socket == NULL) {
-               error = ENOENT;
-               goto out;
-       }
-       error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(*(kauth_cred_t)0);
-out:
-       splx(s);
+       }
+       /*
+        * We are done if there is no pcb
+        */
+       if (n == 0) {
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (0);
+       }
+
+       inp_list = _MALLOC(n * sizeof (*inp_list), M_TEMP, M_WAITOK);
+       if (inp_list == 0) {
+               lck_rw_done(tcbinfo.ipi_lock);
+               return (ENOMEM);
+       }
+
+       n = get_tcp_inp_list(inp_list, n, gencnt);
+
+       error = 0;
+       for (i = 0; i < n; i++) {
+               struct xtcpcb64 xt;
+               struct inpcb *inp;
+               
+               inp = inp_list[i];
+
+               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING)
+                       continue;
+               tcp_lock(inp->inp_socket, 1, NULL);
+               if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
+                       tcp_unlock(inp->inp_socket, 1, NULL);
+                       continue;
+               }
+               if (inp->inp_gencnt > gencnt) {
+                       tcp_unlock(inp->inp_socket, 1, NULL);
+                       continue;
+               }
+
+               bzero(&xt, sizeof(xt));
+               xt.xt_len = sizeof(xt);
+               inpcb_to_xinpcb64(inp, &xt.xt_inpcb);
+               xt.xt_inpcb.inp_ppcb =
+                   (uint64_t)VM_KERNEL_ADDRPERM(inp->inp_ppcb);
+               if (inp->inp_ppcb != NULL)
+                       tcpcb_to_xtcpcb64((struct tcpcb *)inp->inp_ppcb,
+                           &xt);
+               if (inp->inp_socket)
+                       sotoxsocket64(inp->inp_socket,
+                           &xt.xt_inpcb.xi_socket);
+
+               tcp_unlock(inp->inp_socket, 1, NULL);
+
+               error = SYSCTL_OUT(req, &xt, sizeof(xt));
+       }
+       if (!error) {
+                       /*
+                        * Give the user an updated idea of our state.
+                        * If the generation differs from what we told
+                        * her before, she knows that something happened
+                        * while we were processing this request, and it
+                        * might be necessary to retry.
+                        */
+                       bzero(&xig, sizeof(xig));
+                       xig.xig_len = sizeof(xig);
+                       xig.xig_gen = tcbinfo.ipi_gencnt;
+                       xig.xig_sogen = so_gencnt;
+                       xig.xig_count = tcbinfo.ipi_count;
+                       error = SYSCTL_OUT(req, &xig, sizeof(xig));
+       }
+       FREE(inp_list, M_TEMP);
+       lck_rw_done(tcbinfo.ipi_lock);
        return (error);
 }
 
-SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW,
-    0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection");
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, pcblist64,
+           CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
+           tcp_pcblist64, "S,xtcpcb64", "List of active TCP connections");
+
 
-#if INET6
 static int
-tcp6_getcred(SYSCTL_HANDLER_ARGS)
+tcp_pcblist_n SYSCTL_HANDLER_ARGS
 {
-       struct sockaddr_in6 addrs[2];
-       struct inpcb *inp;
-       int error, s, mapped = 0;
+#pragma unused(oidp, arg1, arg2)
+       int error = 0;
+
+       error = get_pcblist_n(IPPROTO_TCP, req, &tcbinfo);
 
-       error = suser(req->p);
-       if (error)
-               return (error);
-       error = SYSCTL_IN(req, addrs, sizeof(addrs));
-       if (error)
-               return (error);
-       if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
-               if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
-                       mapped = 1;
-               else
-                       return (EINVAL);
-       }
-       s = splnet();
-       if (mapped == 1)
-               inp = in_pcblookup_hash(&tcbinfo,
-                       *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
-                       addrs[1].sin6_port,
-                       *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
-                       addrs[0].sin6_port,
-                       0, NULL);
-       else
-               inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr,
-                                addrs[1].sin6_port,
-                                &addrs[0].sin6_addr, addrs[0].sin6_port,
-                                0, NULL);
-       if (inp == NULL || inp->inp_socket == NULL) {
-               error = ENOENT;
-               goto out;
-       }
-       error = SYSCTL_OUT(req, inp->inp_socket->so_cred, 
-                          sizeof(*(kauth_cred_t)0);
-out:
-       splx(s);
        return (error);
 }
 
-SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW,
-           0, 0,
-           tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection");
+
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, pcblist_n,
+           CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
+           tcp_pcblist_n, "S,xtcpcb_n", "List of active TCP connections");
+
+
+__private_extern__ void
+tcp_get_ports_used(uint32_t ifindex, int protocol, uint32_t flags,
+    bitstr_t *bitfield)
+{
+       inpcb_get_ports_used(ifindex, protocol, flags,
+               bitfield, &tcbinfo);
+}
+
+__private_extern__ uint32_t
+tcp_count_opportunistic(unsigned int ifindex, u_int32_t flags)
+{
+       return (inpcb_count_opportunistic(ifindex, &tcbinfo, flags));
+}
+
+__private_extern__ uint32_t
+tcp_find_anypcb_byaddr(struct ifaddr *ifa)
+{
+       return (inpcb_find_anypcb_byaddr(ifa, &tcbinfo));
+}
+
+static void
+tcp_handle_msgsize(struct ip *ip, struct inpcb *inp)
+{
+       struct rtentry *rt = NULL;
+       u_short ifscope = IFSCOPE_NONE;
+       int mtu;
+       struct sockaddr_in icmpsrc = {
+           sizeof (struct sockaddr_in),
+           AF_INET, 0, { 0 },
+           { 0, 0, 0, 0, 0, 0, 0, 0 } };
+       struct icmp *icp = NULL;
+
+       icp = (struct icmp *)(void *)
+           ((caddr_t)ip - offsetof(struct icmp, icmp_ip));
+
+       icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
+
+       /*
+        * MTU discovery:
+        * If we got a needfrag and there is a host route to the
+        * original destination, and the MTU is not locked, then
+        * set the MTU in the route to the suggested new value
+        * (if given) and then notify as usual.  The ULPs will
+        * notice that the MTU has changed and adapt accordingly.
+        * If no new MTU was suggested, then we guess a new one
+        * less than the current value.  If the new MTU is
+        * unreasonably small (defined by sysctl tcp_minmss), then
+        * we reset the MTU to the interface value and enable the
+        * lock bit, indicating that we are no longer doing MTU
+        * discovery.
+        */
+       if (ROUTE_UNUSABLE(&(inp->inp_route)) == false)
+               rt = inp->inp_route.ro_rt;
+
+       /*
+        * icmp6_mtudisc_update scopes the routing lookup
+        * to the incoming interface (delivered from mbuf
+        * packet header.
+        * That is mostly ok but for asymmetric networks
+        * that may be an issue.
+        * Frag needed OR Packet too big really communicates
+        * MTU for the out data path.
+        * Take the interface scope from cached route or
+        * the last outgoing interface from inp
+        */
+       if (rt != NULL)
+               ifscope = (rt->rt_ifp != NULL) ?
+                   rt->rt_ifp->if_index : IFSCOPE_NONE;
+       else
+               ifscope = (inp->inp_last_outifp != NULL) ?
+                   inp->inp_last_outifp->if_index : IFSCOPE_NONE;
+
+       if ((rt == NULL) ||
+           !(rt->rt_flags & RTF_HOST) ||
+           (rt->rt_flags & (RTF_CLONING | RTF_PRCLONING))) {
+               rt = rtalloc1_scoped((struct sockaddr *)&icmpsrc, 0,
+                   RTF_CLONING | RTF_PRCLONING, ifscope);
+       } else if (rt) {
+               RT_LOCK(rt);
+               rtref(rt);
+               RT_UNLOCK(rt);
+       }
+
+       if (rt != NULL) {
+               RT_LOCK(rt);
+               if ((rt->rt_flags & RTF_HOST) &&
+                   !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
+                       mtu = ntohs(icp->icmp_nextmtu);
+                       /*
+                        * XXX Stock BSD has changed the following
+                        * to compare with icp->icmp_ip.ip_len
+                        * to converge faster when sent packet
+                        * < route's MTU. We may want to adopt
+                        * that change.
+                        */
+                       if (mtu == 0)
+                               mtu = ip_next_mtu(rt->rt_rmx.
+                                   rmx_mtu, 1);
+#if DEBUG_MTUDISC
+                       printf("MTU for %s reduced to %d\n",
+                           inet_ntop(AF_INET,
+                           &icmpsrc.sin_addr, ipv4str,
+                           sizeof (ipv4str)), mtu);
 #endif
-#endif /* __APPLE__*/
+                       if (mtu < max(296, (tcp_minmss +
+                           sizeof (struct tcpiphdr)))) {
+                               rt->rt_rmx.rmx_locks |= RTV_MTU;
+                       } else if (rt->rt_rmx.rmx_mtu > mtu) {
+                               rt->rt_rmx.rmx_mtu = mtu;
+                       }
+               }
+               RT_UNLOCK(rt);
+               rtfree(rt);
+       }
+}
 
 void
-tcp_ctlinput(cmd, sa, vip)
-       int cmd;
-       struct sockaddr *sa;
-       void *vip;
+tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
 {
+       tcp_seq icmp_tcp_seq;
        struct ip *ip = vip;
-       struct tcphdr *th;
        struct in_addr faddr;
        struct inpcb *inp;
        struct tcpcb *tp;
+
        void (*notify)(struct inpcb *, int) = tcp_notify;
-       tcp_seq icmp_seq;
-       int s;
 
-       faddr = ((struct sockaddr_in *)sa)->sin_addr;
+       faddr = ((struct sockaddr_in *)(void *)sa)->sin_addr;
        if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
                return;
 
-       if (cmd == PRC_QUENCH)
-               notify = tcp_quench;
+       if ((unsigned)cmd >= PRC_NCMDS)
+               return;
+
+       if (cmd == PRC_MSGSIZE)
+               notify = tcp_mtudisc;
        else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
                cmd == PRC_UNREACH_PORT) && ip)
                notify = tcp_drop_syn_sent;
-       else if (cmd == PRC_MSGSIZE)
-               notify = tcp_mtudisc;
        else if (PRC_IS_REDIRECT(cmd)) {
                ip = 0;
                notify = in_rtchange;
        } else if (cmd == PRC_HOSTDEAD)
                ip = 0;
-       else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)
+       /* Source quench is deprecated */
+       else if (cmd == PRC_QUENCH)
+               return;
+       else if (inetctlerrmap[cmd] == 0)
                return;
        if (ip) {
-               th = (struct tcphdr *)((caddr_t)ip 
-                                      + (IP_VHL_HL(ip->ip_vhl) << 2));
-               inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport,
-                   ip->ip_src, th->th_sport, 0, NULL);
+               struct tcphdr th;
+               struct icmp *icp;
+
+               icp = (struct icmp *)(void *)
+                   ((caddr_t)ip - offsetof(struct icmp, icmp_ip));
+               /*
+                * Only the first 8 bytes of TCP header will be returned.
+                */
+               bzero(&th, sizeof(th));
+               bcopy(((caddr_t)ip + (IP_VHL_HL(ip->ip_vhl) << 2)), &th, 8);
+               inp = in_pcblookup_hash(&tcbinfo, faddr, th.th_dport,
+                   ip->ip_src, th.th_sport, 0, NULL);
                if (inp != NULL && inp->inp_socket != NULL) {
                        tcp_lock(inp->inp_socket, 1, 0);
-                       if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
+                       if (in_pcb_checkstate(inp, WNT_RELEASE, 1) ==
+                           WNT_STOPUSING) {
                                tcp_unlock(inp->inp_socket, 1, 0);
                                return;
                        }
-                       icmp_seq = htonl(th->th_seq);
+                       icmp_tcp_seq = htonl(th.th_seq);
                        tp = intotcpcb(inp);
-                       if (SEQ_GEQ(icmp_seq, tp->snd_una) &&
-                           SEQ_LT(icmp_seq, tp->snd_max))
+                       if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
+                           SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
+                               if (cmd == PRC_MSGSIZE)
+                                       tcp_handle_msgsize(ip, inp);
+
                                (*notify)(inp, inetctlerrmap[cmd]);
+                       }
                        tcp_unlock(inp->inp_socket, 1, 0);
                }
        } else
@@ -1276,10 +2288,7 @@ tcp_ctlinput(cmd, sa, vip)
 
 #if INET6
 void
-tcp6_ctlinput(cmd, sa, d)
-       int cmd;
-       struct sockaddr *sa;
-       void *d;
+tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
 {
        struct tcphdr th;
        void (*notify)(struct inpcb *, int) = tcp_notify;
@@ -1297,12 +2306,15 @@ tcp6_ctlinput(cmd, sa, d)
            sa->sa_len != sizeof(struct sockaddr_in6))
                return;
 
-       if (cmd == PRC_QUENCH)
-               notify = tcp_quench;
-       else if (cmd == PRC_MSGSIZE)
+       if ((unsigned)cmd >= PRC_NCMDS)
+               return;
+
+       if (cmd == PRC_MSGSIZE)
                notify = tcp_mtudisc;
-       else if (!PRC_IS_REDIRECT(cmd) &&
-                ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
+       else if (!PRC_IS_REDIRECT(cmd) && (inet6ctlerrmap[cmd] == 0))
+               return;
+       /* Source quench is deprecated */
+       else if (cmd == PRC_QUENCH)
                return;
 
        /* if the parameter is from icmp6, decode it. */
@@ -1334,10 +2346,11 @@ tcp6_ctlinput(cmd, sa, d)
 
                in6_pcbnotify(&tcbinfo, sa, th.th_dport,
                    (struct sockaddr *)ip6cp->ip6c_src,
-                   th.th_sport, cmd, notify);
-       } else
-               in6_pcbnotify(&tcbinfo, sa, 0, (struct sockaddr *)sa6_src,
-                             0, cmd, notify);
+                   th.th_sport, cmd, NULL, notify);
+       } else {
+               in6_pcbnotify(&tcbinfo, sa, 0,
+                   (struct sockaddr *)(size_t)sa6_src, 0, cmd, NULL, notify);
+       }
 }
 #endif /* INET6 */
 
@@ -1349,7 +2362,7 @@ tcp6_ctlinput(cmd, sa, d)
  * 1.  In SYN-ACK packets.
  * 2.  In SYN packets.
  *
- * The ISNs in SYN-ACK packets have no monotonicity requirement, 
+ * The ISNs in SYN-ACK packets have no monotonicity requirement,
  * and should be as unpredictable as possible to avoid the possibility
  * of spoofing and/or connection hijacking.  To satisfy this
  * requirement, SYN-ACK ISNs are generated via the arc4random()
@@ -1385,91 +2398,76 @@ tcp6_ctlinput(cmd, sa, d)
  *
  */
 
-#define ISN_BYTES_PER_SECOND 1048576
-
-u_char isn_secret[32];
-int isn_last_reseed;
-MD5_CTX isn_ctx;
+#define        ISN_BYTES_PER_SECOND 1048576
 
 tcp_seq
-tcp_new_isn(tp)
-       struct tcpcb *tp;
+tcp_new_isn(struct tcpcb *tp)
 {
        u_int32_t md5_buffer[4];
        tcp_seq new_isn;
-       struct timeval time;
+       struct timeval timenow;
+       u_char isn_secret[32];
+       int isn_last_reseed = 0;
+       MD5_CTX isn_ctx;
 
        /* Use arc4random for SYN-ACKs when not in exact RFC1948 mode. */
-       if (((tp->t_state == TCPS_LISTEN) || (tp->t_state == TCPS_TIME_WAIT))
-          && tcp_strict_rfc1948 == 0)
+       if (((tp->t_state == TCPS_LISTEN) || (tp->t_state == TCPS_TIME_WAIT)) &&
+           tcp_strict_rfc1948 == 0)
 #ifdef __APPLE__
-               return random();
+               return (RandomULong());
 #else
-               return arc4random();
+               return (arc4random());
 #endif
+       getmicrotime(&timenow);
 
        /* Seed if this is the first use, reseed if requested. */
        if ((isn_last_reseed == 0) ||
            ((tcp_strict_rfc1948 == 0) && (tcp_isn_reseed_interval > 0) &&
-            (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
-               < (u_int)time.tv_sec))) {
+           (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
+               < (u_int)timenow.tv_sec))) {
 #ifdef __APPLE__
                read_random(&isn_secret, sizeof(isn_secret));
 #else
                read_random_unlimited(&isn_secret, sizeof(isn_secret));
 #endif
-               isn_last_reseed = time.tv_sec;
+               isn_last_reseed = timenow.tv_sec;
        }
-               
+
        /* Compute the md5 hash and return the ISN. */
        MD5Init(&isn_ctx);
-       MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
-       MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
+       MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport,
+           sizeof(u_short));
+       MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport,
+           sizeof(u_short));
 #if INET6
        if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
                MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
-                         sizeof(struct in6_addr));
+                   sizeof(struct in6_addr));
                MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
-                         sizeof(struct in6_addr));
+                   sizeof(struct in6_addr));
        } else
 #endif
        {
                MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
-                         sizeof(struct in_addr));
+                   sizeof(struct in_addr));
                MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
-                         sizeof(struct in_addr));
+                   sizeof(struct in_addr));
        }
        MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
        MD5Final((u_char *) &md5_buffer, &isn_ctx);
        new_isn = (tcp_seq) md5_buffer[0];
-       new_isn += time.tv_sec * (ISN_BYTES_PER_SECOND / hz);
-       return new_isn;
+       new_isn += timenow.tv_sec * (ISN_BYTES_PER_SECOND / hz);
+       return (new_isn);
 }
 
+
 /*
- * When a source quench is received, close congestion window
- * to one segment.  We will gradually open it again as we proceed.
+ * When a specific ICMP unreachable message is received and the
+ * connection state is SYN-SENT, drop the connection.  This behavior
+ * is controlled by the icmp_may_rst sysctl.
  */
 void
-tcp_quench(inp, errno)
-       struct inpcb *inp;
-       int errno;
-{
-       struct tcpcb *tp = intotcpcb(inp);
-
-       if (tp)
-               tp->snd_cwnd = tp->t_maxseg;
-}
-
-/*
- * When a specific ICMP unreachable message is received and the
- * connection state is SYN-SENT, drop the connection.  This behavior
- * is controlled by the icmp_may_rst sysctl.
- */
-void
-tcp_drop_syn_sent(inp, errno)
-       struct inpcb *inp;
-       int errno;
+tcp_drop_syn_sent(struct inpcb *inp, int errno)
 {
        struct tcpcb *tp = intotcpcb(inp);
 
@@ -1484,9 +2482,10 @@ tcp_drop_syn_sent(inp, errno)
  * This duplicates some code in the tcp_mss() function in tcp_input.c.
  */
 void
-tcp_mtudisc(inp, errno)
-       struct inpcb *inp;
-       int errno;
+tcp_mtudisc(
+       struct inpcb *inp,
+       __unused int errno
+)
 {
        struct tcpcb *tp = intotcpcb(inp);
        struct rtentry *rt;
@@ -1494,37 +2493,47 @@ tcp_mtudisc(inp, errno)
        struct socket *so = inp->inp_socket;
        int offered;
        int mss;
+       u_int32_t mtu;
+       u_int32_t protoHdrOverhead = sizeof (struct tcpiphdr);
 #if INET6
        int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
+
+       if (isipv6)
+               protoHdrOverhead = sizeof(struct ip6_hdr) +
+                   sizeof(struct tcphdr);
 #endif /* INET6 */
 
        if (tp) {
 #if INET6
                if (isipv6)
-                       rt = tcp_rtlookup6(inp);
+                       rt = tcp_rtlookup6(inp, IFSCOPE_NONE);
                else
 #endif /* INET6 */
-               rt = tcp_rtlookup(inp);
+                       rt = tcp_rtlookup(inp, IFSCOPE_NONE);
                if (!rt || !rt->rt_rmx.rmx_mtu) {
                        tp->t_maxopd = tp->t_maxseg =
 #if INET6
                                isipv6 ? tcp_v6mssdflt :
 #endif /* INET6 */
                                tcp_mssdflt;
+
+                       /* Route locked during lookup above */
+                       if (rt != NULL)
+                               RT_UNLOCK(rt);
                        return;
                }
                taop = rmx_taop(rt->rt_rmx);
                offered = taop->tao_mssopt;
-               mss = rt->rt_rmx.rmx_mtu -
-#if INET6
-                       (isipv6 ?
-                        sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
-#endif /* INET6 */
-                        sizeof(struct tcpiphdr)
-#if INET6
-                        )
-#endif /* INET6 */
-                       ;
+               mtu = rt->rt_rmx.rmx_mtu;
+
+               /* Route locked during lookup above */
+               RT_UNLOCK(rt);
+
+#if NECP
+               // Adjust MTU if necessary.
+               mtu = necp_socket_get_effective_mtu(inp, mtu);
+#endif /* NECP */
+               mss = mtu - protoHdrOverhead;
 
                if (offered)
                        mss = min(mss, offered);
@@ -1552,15 +2561,21 @@ tcp_mtudisc(inp, errno)
                if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
                    (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
                        mss -= TCPOLEN_TSTAMP_APPA;
-               if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
-                   (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)
-                       mss -= TCPOLEN_CC_APPA;
 
+#if MPTCP
+               mss -= mptcp_adj_mss(tp, TRUE);
+#endif
                if (so->so_snd.sb_hiwat < mss)
                        mss = so->so_snd.sb_hiwat;
 
                tp->t_maxseg = mss;
 
+               /*
+                * Reset the slow-start flight size as it may depends on the
+                * new MSS
+                */
+               if (CC_ALGO(tp)->cwnd_init != NULL)
+                       CC_ALGO(tp)->cwnd_init(tp);
                tcpstat.tcps_mturesent++;
                tp->t_rtttime = 0;
                tp->snd_nxt = tp->snd_una;
@@ -1572,65 +2587,200 @@ tcp_mtudisc(inp, errno)
  * Look-up the routing entry to the peer of this inpcb.  If no route
  * is found and it cannot be allocated the return NULL.  This routine
  * is called by TCP routines that access the rmx structure and by tcp_mss
- * to get the interface MTU.
+ * to get the interface MTU.  If a route is found, this routine will
+ * hold the rtentry lock; the caller is responsible for unlocking.
  */
 struct rtentry *
-tcp_rtlookup(inp)
-       struct inpcb *inp;
+tcp_rtlookup(struct inpcb *inp, unsigned int input_ifscope)
 {
        struct route *ro;
        struct rtentry *rt;
+       struct tcpcb *tp;
+
+       lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
 
        ro = &inp->inp_route;
-       if (ro == NULL)
-               return (NULL);
-       rt = ro->ro_rt;
-       if (rt == NULL || !(rt->rt_flags & RTF_UP) || rt->generation_id != route_generation) {
+       if ((rt = ro->ro_rt) != NULL)
+               RT_LOCK(rt);
+
+       if (ROUTE_UNUSABLE(ro)) {
+               if (rt != NULL) {
+                       RT_UNLOCK(rt);
+                       rt = NULL;
+               }
+               ROUTE_RELEASE(ro);
                /* No route yet, so try to acquire one */
                if (inp->inp_faddr.s_addr != INADDR_ANY) {
+                       unsigned int ifscope;
+
                        ro->ro_dst.sa_family = AF_INET;
                        ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
-                       ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
+                       ((struct sockaddr_in *)(void *)&ro->ro_dst)->sin_addr =
                                inp->inp_faddr;
-                       rtalloc(ro);
-                       rt = ro->ro_rt;
+
+                       /*
+                        * If the socket was bound to an interface, then
+                        * the bound-to-interface takes precedence over
+                        * the inbound interface passed in by the caller
+                        * (if we get here as part of the output path then
+                        * input_ifscope is IFSCOPE_NONE).
+                        */
+                       ifscope = (inp->inp_flags & INP_BOUND_IF) ?
+                           inp->inp_boundifp->if_index : input_ifscope;
+
+                       rtalloc_scoped(ro, ifscope);
+                       if ((rt = ro->ro_rt) != NULL)
+                               RT_LOCK(rt);
                }
        }
-       return rt;
+       if (rt != NULL)
+               RT_LOCK_ASSERT_HELD(rt);
+
+       /*
+        * Update MTU discovery determination. Don't do it if:
+        *      1) it is disabled via the sysctl
+        *      2) the route isn't up
+        *      3) the MTU is locked (if it is, then discovery has been
+        *         disabled)
+        */
+
+       tp = intotcpcb(inp);
+
+       if (!path_mtu_discovery || ((rt != NULL) &&
+           (!(rt->rt_flags & RTF_UP) || (rt->rt_rmx.rmx_locks & RTV_MTU))))
+               tp->t_flags &= ~TF_PMTUD;
+       else
+               tp->t_flags |= TF_PMTUD;
+
+       if (rt != NULL && rt->rt_ifp != NULL) {
+               somultipages(inp->inp_socket,
+                   (rt->rt_ifp->if_hwassist & IFNET_MULTIPAGES));
+               tcp_set_tso(tp, rt->rt_ifp);
+               soif2kcl(inp->inp_socket,
+                   (rt->rt_ifp->if_eflags & IFEF_2KCL));
+               tcp_set_ecn(tp, rt->rt_ifp);
+               if (inp->inp_last_outifp == NULL)
+                       inp->inp_last_outifp = rt->rt_ifp;
+       }
+
+       /* Note if the peer is local */
+       if (rt != NULL && !(rt->rt_ifp->if_flags & IFF_POINTOPOINT) &&
+               (rt->rt_gateway->sa_family == AF_LINK ||
+               rt->rt_ifp->if_flags & IFF_LOOPBACK ||
+               in_localaddr(inp->inp_faddr))) {
+               tp->t_flags |= TF_LOCAL;
+       }
+
+       /*
+        * Caller needs to call RT_UNLOCK(rt).
+        */
+       return (rt);
 }
 
 #if INET6
 struct rtentry *
-tcp_rtlookup6(inp)
-       struct inpcb *inp;
+tcp_rtlookup6(struct inpcb *inp, unsigned int input_ifscope)
 {
        struct route_in6 *ro6;
        struct rtentry *rt;
+       struct tcpcb *tp;
+
+       lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_NOTOWNED);
 
        ro6 = &inp->in6p_route;
-       rt = ro6->ro_rt;
-       if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
+       if ((rt = ro6->ro_rt) != NULL)
+               RT_LOCK(rt);
+
+       if (ROUTE_UNUSABLE(ro6)) {
+               if (rt != NULL) {
+                       RT_UNLOCK(rt);
+                       rt = NULL;
+               }
+               ROUTE_RELEASE(ro6);
                /* No route yet, so try to acquire one */
                if (!IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) {
                        struct sockaddr_in6 *dst6;
+                       unsigned int ifscope;
 
                        dst6 = (struct sockaddr_in6 *)&ro6->ro_dst;
                        dst6->sin6_family = AF_INET6;
                        dst6->sin6_len = sizeof(*dst6);
                        dst6->sin6_addr = inp->in6p_faddr;
-                       rtalloc((struct route *)ro6);
-                       rt = ro6->ro_rt;
+
+                       /*
+                        * If the socket was bound to an interface, then
+                        * the bound-to-interface takes precedence over
+                        * the inbound interface passed in by the caller
+                        * (if we get here as part of the output path then
+                        * input_ifscope is IFSCOPE_NONE).
+                        */
+                       ifscope = (inp->inp_flags & INP_BOUND_IF) ?
+                           inp->inp_boundifp->if_index : input_ifscope;
+
+                       rtalloc_scoped((struct route *)ro6, ifscope);
+                       if ((rt = ro6->ro_rt) != NULL)
+                               RT_LOCK(rt);
                }
        }
-       return rt;
+       if (rt != NULL)
+               RT_LOCK_ASSERT_HELD(rt);
+
+       /*
+        * Update path MTU Discovery determination
+        * while looking up the route:
+        *  1) we have a valid route to the destination
+        *  2) the MTU is not locked (if it is, then discovery has been
+        *    disabled)
+        */
+
+
+       tp = intotcpcb(inp);
+
+       /*
+        * Update MTU discovery determination. Don't do it if:
+        *      1) it is disabled via the sysctl
+        *      2) the route isn't up
+        *      3) the MTU is locked (if it is, then discovery has been
+        *         disabled)
+        */
+
+       if (!path_mtu_discovery || ((rt != NULL) &&
+           (!(rt->rt_flags & RTF_UP) || (rt->rt_rmx.rmx_locks & RTV_MTU))))
+               tp->t_flags &= ~TF_PMTUD;
+       else
+               tp->t_flags |= TF_PMTUD;
+
+       if (rt != NULL && rt->rt_ifp != NULL) {
+               somultipages(inp->inp_socket,
+                   (rt->rt_ifp->if_hwassist & IFNET_MULTIPAGES));
+               tcp_set_tso(tp, rt->rt_ifp);
+               soif2kcl(inp->inp_socket,
+                   (rt->rt_ifp->if_eflags & IFEF_2KCL));
+               tcp_set_ecn(tp, rt->rt_ifp);
+               if (inp->inp_last_outifp == NULL)
+                       inp->inp_last_outifp = rt->rt_ifp;
+       }
+
+       /* Note if the peer is local */
+       if (rt != NULL && !(rt->rt_ifp->if_flags & IFF_POINTOPOINT) &&
+               (IN6_IS_ADDR_LOOPBACK(&inp->in6p_faddr) ||
+               IN6_IS_ADDR_LINKLOCAL(&inp->in6p_faddr) ||
+               rt->rt_gateway->sa_family == AF_LINK ||
+               in6_localaddr(&inp->in6p_faddr))) {
+               tp->t_flags |= TF_LOCAL;
+       }
+
+       /*
+        * Caller needs to call RT_UNLOCK(rt).
+        */
+       return (rt);
 }
 #endif /* INET6 */
 
 #if IPSEC
 /* compute ESP/AH header size for TCP, including outer IP header. */
 size_t
-ipsec_hdrsiz_tcp(tp)
-       struct tcpcb *tp;
+ipsec_hdrsiz_tcp(struct tcpcb *tp)
 {
        struct inpcb *inp;
        struct mbuf *m;
@@ -1642,34 +2792,32 @@ ipsec_hdrsiz_tcp(tp)
        struct tcphdr *th;
 
        if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
-               return 0;
-       MGETHDR(m, M_DONTWAIT, MT_DATA);
+               return (0);
+       MGETHDR(m, M_DONTWAIT, MT_DATA);        /* MAC-OK */
        if (!m)
-               return 0;
+               return (0);
 
-       lck_mtx_lock(sadb_mutex);
 #if INET6
        if ((inp->inp_vflag & INP_IPV6) != 0) {
                ip6 = mtod(m, struct ip6_hdr *);
-               th = (struct tcphdr *)(ip6 + 1);
+               th = (struct tcphdr *)(void *)(ip6 + 1);
                m->m_pkthdr.len = m->m_len =
                        sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
                tcp_fillheaders(tp, ip6, th);
                hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
        } else
 #endif /* INET6 */
-      {
-       ip = mtod(m, struct ip *);
-       th = (struct tcphdr *)(ip + 1);
-       m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
-       tcp_fillheaders(tp, ip, th);
-       hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
-      }
-       lck_mtx_unlock(sadb_mutex);
+       {
+               ip = mtod(m, struct ip *);
+               th = (struct tcphdr *)(ip + 1);
+               m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
+               tcp_fillheaders(tp, ip, th);
+               hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
+       }
        m_free(m);
-       return hdrsiz;
+       return (hdrsiz);
 }
-#endif /*IPSEC*/
+#endif /* IPSEC */
 
 /*
  * Return a pointer to the cached information about the remote host.
@@ -1677,24 +2825,31 @@ ipsec_hdrsiz_tcp(tp)
  * the route metrics.
  */
 struct rmxp_tao *
-tcp_gettaocache(inp)
-       struct inpcb *inp;
+tcp_gettaocache(struct inpcb *inp)
 {
        struct rtentry *rt;
+       struct rmxp_tao *taop;
 
 #if INET6
        if ((inp->inp_vflag & INP_IPV6) != 0)
-               rt = tcp_rtlookup6(inp);
+               rt = tcp_rtlookup6(inp, IFSCOPE_NONE);
        else
 #endif /* INET6 */
-       rt = tcp_rtlookup(inp);
+       rt = tcp_rtlookup(inp, IFSCOPE_NONE);
 
        /* Make sure this is a host route and is up. */
        if (rt == NULL ||
-           (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
-               return NULL;
+           (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) {
+               /* Route locked during lookup above */
+               if (rt != NULL)
+                       RT_UNLOCK(rt);
+               return (NULL);
+       }
 
-       return rmx_taop(rt->rt_rmx);
+       taop = rmx_taop(rt->rt_rmx);
+       /* Route locked during lookup above */
+       RT_UNLOCK(rt);
+       return (taop);
 }
 
 /*
@@ -1706,91 +2861,962 @@ tcp_gettaocache(inp)
  * nothing in the cache left over.
  */
 static void
-tcp_cleartaocache()
+tcp_cleartaocache(void)
 {
 }
 
 int
-tcp_lock(so, refcount, lr)
-       struct socket *so;
-       int refcount;
-       int lr;
+tcp_lock(struct socket *so, int refcount, void *lr)
 {
-       int lr_saved;
-#ifdef __ppc__
-       if (lr == 0) {
-               __asm__ volatile("mflr %0" : "=r" (lr_saved));
-       }
-       else lr_saved = lr;
-#endif
+       void *lr_saved;
 
-       if (so->so_pcb) {
-               lck_mtx_lock(((struct inpcb *)so->so_pcb)->inpcb_mtx);
-       }
-       else  {
-               panic("tcp_lock: so=%x NO PCB! lr=%x\n", so, lr_saved);
-               lck_mtx_lock(so->so_proto->pr_domain->dom_mtx);
+       if (lr == NULL)
+               lr_saved = __builtin_return_address(0);
+       else
+               lr_saved = lr;
+
+       if (so->so_pcb != NULL) {
+               lck_mtx_lock(&((struct inpcb *)so->so_pcb)->inpcb_mtx);
+       } else  {
+               panic("tcp_lock: so=%p NO PCB! lr=%p lrh= %s\n",
+                   so, lr_saved, solockhistory_nr(so));
+               /* NOTREACHED */
        }
 
-       if (so->so_usecount < 0)
-               panic("tcp_lock: so=%x so_pcb=%x lr=%x ref=%x\n",
-               so, so->so_pcb, lr_saved, so->so_usecount);
-
+       if (so->so_usecount < 0) {
+               panic("tcp_lock: so=%p so_pcb=%p lr=%p ref=%x lrh= %s\n",
+                   so, so->so_pcb, lr_saved, so->so_usecount,
+                   solockhistory_nr(so));
+               /* NOTREACHED */
+       }
        if (refcount)
                so->so_usecount++;
-       so->reserved3 = (void *)lr_saved;
+       so->lock_lr[so->next_lock_lr] = lr_saved;
+       so->next_lock_lr = (so->next_lock_lr+1) % SO_LCKDBG_MAX;
        return (0);
 }
 
 int
-tcp_unlock(so, refcount, lr)
-       struct socket *so;
-       int refcount;
-       int lr;
+tcp_unlock(struct socket *so, int refcount, void *lr)
 {
-       int lr_saved;
-#ifdef __ppc__
-       if (lr == 0) {
-               __asm__ volatile("mflr %0" : "=r" (lr_saved));
-       }
-       else lr_saved = lr;
-#endif
+       void *lr_saved;
+
+       if (lr == NULL)
+               lr_saved = __builtin_return_address(0);
+       else
+               lr_saved = lr;
 
 #ifdef MORE_TCPLOCK_DEBUG
-       printf("tcp_unlock: so=%x sopcb=%x lock=%x ref=%x lr=%x\n", 
-               so, so->so_pcb, ((struct inpcb *)so->so_pcb)->inpcb_mtx, so->so_usecount, lr_saved);
+       printf("tcp_unlock: so=0x%llx sopcb=0x%llx lock=0x%llx ref=%x "
+           "lr=0x%llx\n", (uint64_t)VM_KERNEL_ADDRPERM(so),
+           (uint64_t)VM_KERNEL_ADDRPERM(so->so_pcb),
+           (uint64_t)VM_KERNEL_ADDRPERM(&(sotoinpcb(so)->inpcb_mtx)),
+           so->so_usecount, (uint64_t)VM_KERNEL_ADDRPERM(lr_saved));
 #endif
        if (refcount)
                so->so_usecount--;
 
-       if (so->so_usecount < 0)
-               panic("tcp_unlock: so=%x usecount=%x\n", so, so->so_usecount);  
-       if (so->so_pcb == NULL) {
-               panic("tcp_unlock: so=%x NO PCB usecount=%x lr=%x\n", so, so->so_usecount, lr_saved);
-               lck_mtx_unlock(so->so_proto->pr_domain->dom_mtx);
+       if (so->so_usecount < 0) {
+               panic("tcp_unlock: so=%p usecount=%x lrh= %s\n",
+                   so, so->so_usecount, solockhistory_nr(so));
+               /* NOTREACHED */
        }
-       else {
-               lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-               lck_mtx_unlock(((struct inpcb *)so->so_pcb)->inpcb_mtx);
+       if (so->so_pcb == NULL) {
+               panic("tcp_unlock: so=%p NO PCB usecount=%x lr=%p lrh= %s\n",
+                   so, so->so_usecount, lr_saved, solockhistory_nr(so));
+               /* NOTREACHED */
+       } else {
+               lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
+                   LCK_MTX_ASSERT_OWNED);
+               so->unlock_lr[so->next_unlock_lr] = lr_saved;
+               so->next_unlock_lr = (so->next_unlock_lr+1) % SO_LCKDBG_MAX;
+               lck_mtx_unlock(&((struct inpcb *)so->so_pcb)->inpcb_mtx);
        }
-       so->reserved4 = (void *)lr_saved;
        return (0);
 }
 
 lck_mtx_t *
-tcp_getlock(so, locktype)
-       struct socket *so;
-       int locktype;
+tcp_getlock(struct socket *so, __unused int locktype)
 {
        struct inpcb *inp = sotoinpcb(so);
 
        if (so->so_pcb)  {
                if (so->so_usecount < 0)
-                       panic("tcp_getlock: so=%x usecount=%x\n", so, so->so_usecount); 
-               return(inp->inpcb_mtx);
-       }
-       else {
-               panic("tcp_getlock: so=%x NULL so_pcb\n", so);
+                       panic("tcp_getlock: so=%p usecount=%x lrh= %s\n",
+                           so, so->so_usecount, solockhistory_nr(so));
+               return (&inp->inpcb_mtx);
+       } else {
+               panic("tcp_getlock: so=%p NULL so_pcb %s\n",
+                   so, solockhistory_nr(so));
                return (so->so_proto->pr_domain->dom_mtx);
        }
 }
+
+/*
+ * Determine if we can grow the recieve socket buffer to avoid sending
+ * a zero window update to the peer. We allow even socket buffers that
+ * have fixed size (set by the application) to grow if the resource
+ * constraints are met. They will also be trimmed after the application
+ * reads data.
+ */
+static void
+tcp_sbrcv_grow_rwin(struct tcpcb *tp, struct sockbuf *sb)
+{
+       u_int32_t rcvbufinc = tp->t_maxseg << 4;
+       u_int32_t rcvbuf = sb->sb_hiwat;
+       struct socket *so = tp->t_inpcb->inp_socket;
+
+       if (tcp_recv_bg == 1 || IS_TCP_RECV_BG(so))
+               return;
+       /*
+        * If message delivery is enabled, do not count
+        * unordered bytes in receive buffer towards hiwat
+        */
+       if (so->so_flags & SOF_ENABLE_MSGS)
+               rcvbuf = rcvbuf - so->so_msg_state->msg_uno_bytes;
+
+       if (tcp_do_autorcvbuf == 1 &&
+               tcp_cansbgrow(sb) &&
+               (tp->t_flags & TF_SLOWLINK) == 0 &&
+               (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) == 0 &&
+               (rcvbuf - sb->sb_cc) < rcvbufinc &&
+               rcvbuf < tcp_autorcvbuf_max &&
+               (sb->sb_idealsize > 0 &&
+               sb->sb_hiwat <= (sb->sb_idealsize + rcvbufinc))) {
+               sbreserve(sb,
+                   min((sb->sb_hiwat + rcvbufinc), tcp_autorcvbuf_max));
+       }
+}
+
+int32_t
+tcp_sbspace(struct tcpcb *tp)
+{
+       struct socket *so = tp->t_inpcb->inp_socket;
+       struct sockbuf *sb = &so->so_rcv;
+       u_int32_t rcvbuf;
+       int32_t space;
+       int32_t pending = 0;
+
+       tcp_sbrcv_grow_rwin(tp, sb);
+
+       /* hiwat might have changed */
+       rcvbuf = sb->sb_hiwat;
+
+       /*
+        * If message delivery is enabled, do not count
+        * unordered bytes in receive buffer towards hiwat mark.
+        * This value is used to return correct rwnd that does
+        * not reflect the extra unordered bytes added to the
+        * receive socket buffer.
+        */
+       if (so->so_flags & SOF_ENABLE_MSGS)
+               rcvbuf = rcvbuf - so->so_msg_state->msg_uno_bytes;
+
+       space =  ((int32_t) imin((rcvbuf - sb->sb_cc),
+               (sb->sb_mbmax - sb->sb_mbcnt)));
+       if (space < 0)
+               space = 0;
+
+#if CONTENT_FILTER
+       /* Compensate for data being processed by content filters */
+       pending = cfil_sock_data_space(sb);
+#endif /* CONTENT_FILTER */
+       if (pending > space)
+               space = 0;
+       else
+               space -= pending;
+
+       /*
+        * Avoid increasing window size if the current window
+        * is already very low, we could be in "persist" mode and
+        * we could break some apps (see rdar://5409343)
+        */
+
+       if (space < tp->t_maxseg)
+               return (space);
+
+       /* Clip window size for slower link */
+
+       if (((tp->t_flags & TF_SLOWLINK) != 0) && slowlink_wsize > 0)
+               return (imin(space, slowlink_wsize));
+
+       return (space);
+}
+/*
+ * Checks TCP Segment Offloading capability for a given connection
+ * and interface pair.
+ */
+void
+tcp_set_tso(struct tcpcb *tp, struct ifnet *ifp)
+{
+#if INET6
+       struct inpcb *inp;
+       int isipv6;
+#endif /* INET6 */
+#if MPTCP
+       /*
+        * We can't use TSO if this tcpcb belongs to an MPTCP session.
+        */
+       if (tp->t_mpflags & TMPF_MPTCP_TRUE) {
+               tp->t_flags &= ~TF_TSO;
+               return;
+       }
+#endif
+#if INET6
+       inp = tp->t_inpcb;
+       isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
+
+       if (isipv6) {
+               if (ifp && (ifp->if_hwassist & IFNET_TSO_IPV6)) {
+                       tp->t_flags |= TF_TSO;
+                       if (ifp->if_tso_v6_mtu != 0)
+                               tp->tso_max_segment_size = ifp->if_tso_v6_mtu;
+                       else
+                               tp->tso_max_segment_size = TCP_MAXWIN;
+               } else
+                               tp->t_flags &= ~TF_TSO;
+
+       } else
+#endif /* INET6 */
+
+       {
+               if (ifp && (ifp->if_hwassist & IFNET_TSO_IPV4)) {
+                       tp->t_flags |= TF_TSO;
+                       if (ifp->if_tso_v4_mtu != 0)
+                               tp->tso_max_segment_size = ifp->if_tso_v4_mtu;
+                       else
+                               tp->tso_max_segment_size = TCP_MAXWIN;
+               } else
+                               tp->t_flags &= ~TF_TSO;
+       }
+}
+
+#define        TIMEVAL_TO_TCPHZ(_tv_) ((_tv_).tv_sec * TCP_RETRANSHZ + \
+       (_tv_).tv_usec / TCP_RETRANSHZ_TO_USEC)
+
+/*
+ * Function to calculate the tcp clock. The tcp clock will get updated
+ * at the boundaries of the tcp layer. This is done at 3 places:
+ * 1. Right before processing an input tcp packet
+ * 2. Whenever a connection wants to access the network using tcp_usrreqs
+ * 3. When a tcp timer fires or before tcp slow timeout
+ *
+ */
+
+void
+calculate_tcp_clock(void)
+{
+       struct timeval tv = tcp_uptime;
+       struct timeval interval = {0, TCP_RETRANSHZ_TO_USEC};
+       struct timeval now, hold_now;
+       uint32_t incr = 0;
+
+       microuptime(&now);
+
+       /*
+        * Update coarse-grained networking timestamp (in sec.); the idea
+        * is to update the counter returnable via net_uptime() when
+        * we read time.
+        */
+       net_update_uptime_secs(now.tv_sec);
+
+       timevaladd(&tv, &interval);
+       if (timevalcmp(&now, &tv, >)) {
+               /* time to update the clock */
+               lck_spin_lock(tcp_uptime_lock);
+               if (timevalcmp(&tcp_uptime, &now, >=)) {
+                       /* clock got updated while waiting for the lock */
+                       lck_spin_unlock(tcp_uptime_lock);
+                       return;
+               }
+
+               microuptime(&now);
+               hold_now = now;
+               tv = tcp_uptime;
+               timevalsub(&now, &tv);
+
+               incr = TIMEVAL_TO_TCPHZ(now);
+               if (incr > 0) {
+                       tcp_uptime = hold_now;
+                       tcp_now += incr;
+               }
+
+               lck_spin_unlock(tcp_uptime_lock);
+       }
+}
+
+/*
+ * Compute receive window scaling that we are going to request
+ * for this connection based on  sb_hiwat. Try to leave some
+ * room to potentially increase the window size upto a maximum
+ * defined by the constant tcp_autorcvbuf_max.
+ */
+void
+tcp_set_max_rwinscale(struct tcpcb *tp, struct socket *so,
+    u_int32_t rcvbuf_max)
+{
+       u_int32_t maxsockbufsize;
+       if (!tcp_do_rfc1323) {
+               tp->request_r_scale = 0;
+               return;
+       }
+
+       tp->request_r_scale = max(tcp_win_scale, tp->request_r_scale);
+       maxsockbufsize = ((so->so_rcv.sb_flags & SB_USRSIZE) != 0) ?
+               so->so_rcv.sb_hiwat : rcvbuf_max;
+
+       while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
+               (TCP_MAXWIN << tp->request_r_scale) < maxsockbufsize)
+               tp->request_r_scale++;
+       tp->request_r_scale = min(tp->request_r_scale, TCP_MAX_WINSHIFT);
+
+}
+
+int
+tcp_notsent_lowat_check(struct socket *so) {
+       struct inpcb *inp = sotoinpcb(so);
+       struct tcpcb *tp = NULL;
+       int notsent = 0;
+       if (inp != NULL) {
+               tp = intotcpcb(inp);
+       }
+
+       notsent = so->so_snd.sb_cc -
+               (tp->snd_nxt - tp->snd_una);
+
+       /*
+        * When we send a FIN or SYN, not_sent can be negative.
+        * In that case also we need to send a write event to the
+        * process if it is waiting. In the FIN case, it will
+        * get an error from send because cantsendmore will be set.
+        */
+       if (notsent <= tp->t_notsent_lowat) {
+               return (1);
+       }
+
+       /*
+        * When Nagle's algorithm is not disabled, it is better
+        * to wakeup the client until there is atleast one
+        * maxseg of data to write.
+        */
+       if ((tp->t_flags & TF_NODELAY) == 0 &&
+               notsent > 0 && notsent < tp->t_maxseg) {
+               return (1);
+       }
+       return (0);
+}
+
+void
+tcp_rxtseg_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end)
+{
+       struct tcp_rxt_seg *rxseg = NULL, *prev = NULL, *next = NULL;
+       u_int32_t rxcount = 0;
+
+       if (SLIST_EMPTY(&tp->t_rxt_segments))
+               tp->t_dsack_lastuna = tp->snd_una;
+       /*
+        * First check if there is a segment already existing for this
+        * sequence space.
+        */
+
+       SLIST_FOREACH(rxseg, &tp->t_rxt_segments, rx_link) {
+               if (SEQ_GT(rxseg->rx_start, start))
+                       break;
+               prev = rxseg;
+       }
+       next = rxseg;
+
+       /* check if prev seg is for this sequence */
+       if (prev != NULL && SEQ_LEQ(prev->rx_start, start) &&
+           SEQ_GEQ(prev->rx_end, end)) {
+               prev->rx_count++;
+               return;
+       }
+
+       /*
+        * There are a couple of possibilities at this point.
+        * 1. prev overlaps with the beginning of this sequence
+        * 2. next overlaps with the end of this sequence
+        * 3. there is no overlap.
+        */
+
+       if (prev != NULL && SEQ_GT(prev->rx_end, start)) {
+               if (prev->rx_start == start && SEQ_GT(end, prev->rx_end)) {
+                       start = prev->rx_end + 1;
+                       prev->rx_count++;
+               } else {
+                       prev->rx_end = (start - 1);
+                       rxcount = prev->rx_count;
+               }
+       }
+
+       if (next != NULL && SEQ_LT(next->rx_start, end)) {
+               if (SEQ_LEQ(next->rx_end, end)) {
+                       end = next->rx_start - 1;
+                       next->rx_count++;
+               } else {
+                       next->rx_start = end + 1;
+                       rxcount = next->rx_count;
+               }
+       }
+       if (!SEQ_LT(start, end))
+               return;
+
+       rxseg = (struct tcp_rxt_seg *) zalloc(tcp_rxt_seg_zone);
+       if (rxseg == NULL) {
+               return;
+       }
+       bzero(rxseg, sizeof(*rxseg));
+       rxseg->rx_start = start;
+       rxseg->rx_end = end;
+       rxseg->rx_count = rxcount + 1;
+
+       if (prev != NULL) {
+               SLIST_INSERT_AFTER(prev, rxseg, rx_link);
+       } else {
+               SLIST_INSERT_HEAD(&tp->t_rxt_segments, rxseg, rx_link);
+       }
+}
+
+struct tcp_rxt_seg *
+tcp_rxtseg_find(struct tcpcb *tp, tcp_seq start, tcp_seq end)
+{
+       struct tcp_rxt_seg *rxseg;
+       if (SLIST_EMPTY(&tp->t_rxt_segments))
+               return (NULL);
+
+       SLIST_FOREACH(rxseg, &tp->t_rxt_segments, rx_link) {
+               if (SEQ_LEQ(rxseg->rx_start, start) &&
+                   SEQ_GEQ(rxseg->rx_end, end))
+                       return (rxseg);
+               if (SEQ_GT(rxseg->rx_start, start))
+                       break;
+       }
+       return (NULL);
+}
+
+void
+tcp_rxtseg_clean(struct tcpcb *tp)
+{
+       struct tcp_rxt_seg *rxseg, *next;
+
+       SLIST_FOREACH_SAFE(rxseg, &tp->t_rxt_segments, rx_link, next) {
+               SLIST_REMOVE(&tp->t_rxt_segments, rxseg,
+                   tcp_rxt_seg, rx_link);
+               zfree(tcp_rxt_seg_zone, rxseg);
+       }
+       tp->t_dsack_lastuna = tp->snd_max;
+}
+
+boolean_t
+tcp_rxtseg_detect_bad_rexmt(struct tcpcb *tp, tcp_seq th_ack)
+{
+       boolean_t bad_rexmt;
+       struct tcp_rxt_seg *rxseg;
+
+       if (SLIST_EMPTY(&tp->t_rxt_segments))
+               return (FALSE);
+
+       /*
+        * If all of the segments in this window are not cumulatively
+        * acknowledged, then there can still be undetected packet loss.
+        * Do not restore congestion window in that case.
+        */
+       if (SEQ_LT(th_ack, tp->snd_recover))
+               return (FALSE);
+
+       bad_rexmt = TRUE;
+       SLIST_FOREACH(rxseg, &tp->t_rxt_segments, rx_link) {
+               if (rxseg->rx_count > 1 ||
+                   !(rxseg->rx_flags & TCP_RXT_SPURIOUS)) {
+                       bad_rexmt = FALSE;
+                       break;
+               }
+       }
+       return (bad_rexmt);
+}
+
+boolean_t
+tcp_rxtseg_dsack_for_tlp(struct tcpcb *tp)
+{
+       boolean_t dsack_for_tlp = FALSE;
+       struct tcp_rxt_seg *rxseg;
+       if (SLIST_EMPTY(&tp->t_rxt_segments))
+               return (FALSE);
+
+       SLIST_FOREACH(rxseg, &tp->t_rxt_segments, rx_link) {
+               if (rxseg->rx_count == 1 &&
+                   SLIST_NEXT(rxseg, rx_link) == NULL &&
+                   (rxseg->rx_flags & TCP_RXT_DSACK_FOR_TLP)) {
+                       dsack_for_tlp = TRUE;
+                       break;
+               }
+       }
+       return (dsack_for_tlp);
+}
+
+u_int32_t
+tcp_rxtseg_total_size(struct tcpcb *tp)
+{
+       struct tcp_rxt_seg *rxseg;
+       u_int32_t total_size = 0;
+
+       SLIST_FOREACH(rxseg, &tp->t_rxt_segments, rx_link) {
+               total_size += (rxseg->rx_end - rxseg->rx_start) + 1;
+       }
+       return (total_size);
+}
+
+void
+tcp_get_connectivity_status(struct tcpcb *tp,
+       struct tcp_conn_status *connstatus)
+{
+       if (tp == NULL || connstatus == NULL)
+               return;
+       bzero(connstatus, sizeof(*connstatus));
+       if (tp->t_rxtshift >= TCP_CONNECTIVITY_PROBES_MAX) {
+               if (TCPS_HAVEESTABLISHED(tp->t_state)) {
+                       connstatus->write_probe_failed = 1;
+               } else {
+                       connstatus->conn_probe_failed = 1;
+               }
+       }
+       if (tp->t_rtimo_probes >= TCP_CONNECTIVITY_PROBES_MAX)
+               connstatus->read_probe_failed = 1;
+       if (tp->t_inpcb != NULL && tp->t_inpcb->inp_last_outifp != NULL &&
+           (tp->t_inpcb->inp_last_outifp->if_eflags & IFEF_PROBE_CONNECTIVITY))
+               connstatus->probe_activated = 1;
+}
+
+boolean_t
+tfo_enabled(const struct tcpcb *tp)
+{
+       return ((tp->t_flagsext & TF_FASTOPEN)? TRUE : FALSE);
+}
+
+void
+tcp_disable_tfo(struct tcpcb *tp)
+{
+       tp->t_flagsext &= ~TF_FASTOPEN;
+}
+
+static struct mbuf *
+tcp_make_keepalive_frame(struct tcpcb *tp, struct ifnet *ifp,
+    boolean_t is_probe)
+{
+       struct inpcb *inp = tp->t_inpcb;
+       struct tcphdr *th;
+       u_int8_t *data;
+       int win = 0;
+       struct mbuf *m;
+
+       /*
+        * The code assumes the IP + TCP headers fit in an mbuf packet header
+        */
+       _CASSERT(sizeof(struct ip) + sizeof(struct tcphdr) <= _MHLEN);
+       _CASSERT(sizeof(struct ip6_hdr) + sizeof(struct tcphdr) <= _MHLEN);
+
+       MGETHDR(m, M_WAIT, MT_HEADER);
+       if (m == NULL) {
+               return (NULL);
+       }
+       m->m_pkthdr.pkt_proto = IPPROTO_TCP;
+
+       data = mbuf_datastart(m);
+
+       if (inp->inp_vflag & INP_IPV4) {
+               bzero(data, sizeof(struct ip) + sizeof(struct tcphdr));
+               th = (struct tcphdr *)(void *) (data + sizeof(struct ip));
+               m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
+               m->m_pkthdr.len = m->m_len;
+       } else {
+               VERIFY(inp->inp_vflag & INP_IPV6);
+
+               bzero(data, sizeof(struct ip6_hdr)
+                   + sizeof(struct tcphdr));
+               th = (struct tcphdr *)(void *)(data + sizeof(struct ip6_hdr));
+               m->m_len = sizeof(struct ip6_hdr) +
+                   sizeof(struct tcphdr);
+               m->m_pkthdr.len = m->m_len;
+       }
+
+       tcp_fillheaders(tp, data, th);
+
+       if (inp->inp_vflag & INP_IPV4) {
+               struct ip *ip;
+
+               ip = (__typeof__(ip))(void *)data;
+
+               ip->ip_id = ip_randomid();
+               ip->ip_len = htons(sizeof(struct ip) + sizeof(struct tcphdr));
+               ip->ip_ttl = inp->inp_ip_ttl;
+               ip->ip_tos |= (inp->inp_ip_tos & ~IPTOS_ECN_MASK);
+               ip->ip_sum = in_cksum_hdr(ip);
+       } else {
+               struct ip6_hdr *ip6;
+
+               ip6 = (__typeof__(ip6))(void *)data;
+
+               ip6->ip6_plen = htons(sizeof(struct tcphdr));
+               ip6->ip6_hlim = in6_selecthlim(inp, ifp);
+               ip6->ip6_flow = ip6->ip6_flow & ~IPV6_FLOW_ECN_MASK;
+
+               if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
+                       ip6->ip6_src.s6_addr16[1] = 0;
+               if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
+                       ip6->ip6_dst.s6_addr16[1] = 0;
+       }
+       th->th_flags = TH_ACK;
+
+       win = tcp_sbspace(tp);
+       if (win > ((int32_t)TCP_MAXWIN << tp->rcv_scale))
+           win = (int32_t)TCP_MAXWIN << tp->rcv_scale;
+       th->th_win = htons((u_short) (win >> tp->rcv_scale));
+
+       if (is_probe) {
+               th->th_seq = htonl(tp->snd_una - 1);
+       } else {
+               th->th_seq = htonl(tp->snd_una);
+       }
+       th->th_ack = htonl(tp->rcv_nxt);
+
+       /* Force recompute TCP checksum to be the final value */
+       th->th_sum = 0;
+       if (inp->inp_vflag & INP_IPV4) {
+               th->th_sum = inet_cksum(m, IPPROTO_TCP,
+                   sizeof(struct ip), sizeof(struct tcphdr));
+       } else {
+               th->th_sum = inet6_cksum(m, IPPROTO_TCP,
+                   sizeof(struct ip6_hdr), sizeof(struct tcphdr));
+       }
+
+       return (m);
+}
+
+void
+tcp_fill_keepalive_offload_frames(ifnet_t ifp,
+    struct ifnet_keepalive_offload_frame *frames_array,
+    u_int32_t frames_array_count, size_t frame_data_offset,
+    u_int32_t *used_frames_count)
+{
+       struct inpcb *inp;
+       inp_gen_t gencnt;
+       u_int32_t frame_index = *used_frames_count;
+
+       if (ifp == NULL || frames_array == NULL ||
+           frames_array_count == 0 ||
+           frame_index >= frames_array_count ||
+           frame_data_offset >= IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE)
+               return;
+
+       /*
+        * This function is called outside the regular TCP processing
+        * so we need to update the TCP clock.
+        */
+       calculate_tcp_clock();
+
+       lck_rw_lock_shared(tcbinfo.ipi_lock);
+       gencnt = tcbinfo.ipi_gencnt;
+       LIST_FOREACH(inp, tcbinfo.ipi_listhead, inp_list) {
+               struct socket *so;
+               struct ifnet_keepalive_offload_frame *frame;
+               struct mbuf *m = NULL;
+               struct tcpcb *tp = intotcpcb(inp);
+
+               if (frame_index >= frames_array_count)
+                       break;
+
+               if (inp->inp_gencnt > gencnt ||
+                   inp->inp_state == INPCB_STATE_DEAD)
+                       continue;
+
+               if ((so = inp->inp_socket) == NULL ||
+                   (so->so_state & SS_DEFUNCT))
+                       continue;
+               /*
+                * check for keepalive offload flag without socket
+                * lock to avoid a deadlock
+                */
+               if (!(inp->inp_flags2 & INP2_KEEPALIVE_OFFLOAD)) {
+                       continue;
+               }
+
+               if (!(inp->inp_vflag & (INP_IPV4 | INP_IPV6))) {
+                       continue;
+               }
+               if (inp->inp_ppcb == NULL ||
+                   in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING)
+                       continue;
+               tcp_lock(so, 1, 0);
+               /* Release the want count */
+               if (inp->inp_ppcb == NULL ||
+                   (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING)) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               if ((inp->inp_vflag & INP_IPV4) &&
+                   (inp->inp_laddr.s_addr == INADDR_ANY ||
+                   inp->inp_faddr.s_addr == INADDR_ANY)) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               if ((inp->inp_vflag & INP_IPV6) &&
+                   (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) ||
+                   IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr))) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               if (inp->inp_lport == 0 || inp->inp_fport == 0) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               if (inp->inp_last_outifp == NULL ||
+                   inp->inp_last_outifp->if_index != ifp->if_index) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               if ((inp->inp_vflag & INP_IPV4) && frame_data_offset +
+                   sizeof(struct ip) + sizeof(struct tcphdr) >
+                   IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               } else if (!(inp->inp_vflag & INP_IPV4) && frame_data_offset +
+                   sizeof(struct ip6_hdr) + sizeof(struct tcphdr) >
+                   IFNET_KEEPALIVE_OFFLOAD_FRAME_DATA_SIZE) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               /*
+                * There is no point in waking up the device for connections
+                * that are not established. Long lived connection are meant
+                * for processes that will sent and receive data
+                */
+               if (tp->t_state != TCPS_ESTABLISHED) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               /*
+                * This inp has all the information that is needed to
+                * generate an offload frame.
+                */
+               frame = &frames_array[frame_index];
+               frame->type = IFNET_KEEPALIVE_OFFLOAD_FRAME_TCP;
+               frame->ether_type = (inp->inp_vflag & INP_IPV4) ?
+                   IFNET_KEEPALIVE_OFFLOAD_FRAME_ETHERTYPE_IPV4 :
+                   IFNET_KEEPALIVE_OFFLOAD_FRAME_ETHERTYPE_IPV6;
+               frame->interval = tp->t_keepidle > 0 ? tp->t_keepidle :
+                   tcp_keepidle;
+               frame->keep_cnt = TCP_CONN_KEEPCNT(tp);
+               frame->keep_retry = TCP_CONN_KEEPINTVL(tp);
+               frame->local_port = ntohs(inp->inp_lport);
+               frame->remote_port = ntohs(inp->inp_fport);
+               frame->local_seq = tp->snd_nxt;
+               frame->remote_seq = tp->rcv_nxt;
+               if (inp->inp_vflag & INP_IPV4) {
+                       frame->length = frame_data_offset +
+                           sizeof(struct ip) + sizeof(struct tcphdr);
+                       frame->reply_length =  frame->length;
+
+                       frame->addr_length = sizeof(struct in_addr);
+                       bcopy(&inp->inp_laddr, frame->local_addr,
+                           sizeof(struct in_addr));
+                       bcopy(&inp->inp_faddr, frame->remote_addr,
+                           sizeof(struct in_addr));
+               } else {
+                       struct in6_addr *ip6;
+
+                       frame->length = frame_data_offset +
+                           sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
+                       frame->reply_length =  frame->length;
+
+                       frame->addr_length = sizeof(struct in6_addr);
+                       ip6 = (struct in6_addr *)(void *)frame->local_addr;
+                       bcopy(&inp->in6p_laddr, ip6, sizeof(struct in6_addr));
+                       if (IN6_IS_SCOPE_EMBED(ip6))
+                               ip6->s6_addr16[1] = 0;
+
+                       ip6 = (struct in6_addr *)(void *)frame->remote_addr;
+                       bcopy(&inp->in6p_faddr, ip6, sizeof(struct in6_addr));
+                       if (IN6_IS_SCOPE_EMBED(ip6))
+                               ip6->s6_addr16[1] = 0;
+               }
+
+               /*
+                * First the probe
+                */
+               m = tcp_make_keepalive_frame(tp, ifp, TRUE);
+               if (m == NULL) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               bcopy(m->m_data, frame->data + frame_data_offset,
+                   m->m_len);
+               m_freem(m);
+
+               /*
+                * Now the response packet to incoming probes
+                */
+               m = tcp_make_keepalive_frame(tp, ifp, FALSE);
+               if (m == NULL) {
+                       tcp_unlock(so, 1, 0);
+                       continue;
+               }
+               bcopy(m->m_data, frame->reply_data + frame_data_offset,
+                   m->m_len);
+               m_freem(m);
+
+               frame_index++;
+               tcp_unlock(so, 1, 0);
+       }
+       lck_rw_done(tcbinfo.ipi_lock);
+       *used_frames_count = frame_index;
+}
+
+errno_t
+tcp_notify_ack_id_valid(struct tcpcb *tp, struct socket *so,
+    u_int32_t notify_id)
+{
+       struct tcp_notify_ack_marker *elm;
+
+       if (so->so_snd.sb_cc == 0)
+               return (ENOBUFS);
+
+       SLIST_FOREACH(elm, &tp->t_notify_ack, notify_next) {
+               /* Duplicate id is not allowed */
+               if (elm->notify_id == notify_id)
+                       return (EINVAL);
+               /* Duplicate position is not allowed */
+               if (elm->notify_snd_una == tp->snd_una + so->so_snd.sb_cc)
+                       return (EINVAL);
+       }
+       return (0);
+}
+
+errno_t
+tcp_add_notify_ack_marker(struct tcpcb *tp, u_int32_t notify_id)
+{
+       struct tcp_notify_ack_marker *nm, *elm = NULL;
+       struct socket *so = tp->t_inpcb->inp_socket;
+
+       MALLOC(nm, struct tcp_notify_ack_marker *, sizeof (*nm),
+           M_TEMP, M_WAIT | M_ZERO);
+       if (nm == NULL)
+               return (ENOMEM);
+       nm->notify_id = notify_id;
+       nm->notify_snd_una = tp->snd_una + so->so_snd.sb_cc;
+
+       SLIST_FOREACH(elm, &tp->t_notify_ack, notify_next) {
+               if (SEQ_GT(nm->notify_snd_una, elm->notify_snd_una))
+                       break;
+       }
+
+       if (elm == NULL) {
+               VERIFY(SLIST_EMPTY(&tp->t_notify_ack));
+               SLIST_INSERT_HEAD(&tp->t_notify_ack, nm, notify_next);
+       } else {
+               SLIST_INSERT_AFTER(elm, nm, notify_next);
+       }
+       tp->t_notify_ack_count++;
+       return (0);
+}
+
+void
+tcp_notify_ack_free(struct tcpcb *tp)
+{
+       struct tcp_notify_ack_marker *elm, *next;
+       if (SLIST_EMPTY(&tp->t_notify_ack))
+               return;
+
+       SLIST_FOREACH_SAFE(elm, &tp->t_notify_ack, notify_next, next) {
+               SLIST_REMOVE(&tp->t_notify_ack, elm, tcp_notify_ack_marker,
+                   notify_next);
+               FREE(elm, M_TEMP);
+       }
+       SLIST_INIT(&tp->t_notify_ack);
+       tp->t_notify_ack_count = 0;
+}
+
+inline void
+tcp_notify_acknowledgement(struct tcpcb *tp, struct socket *so)
+{
+       struct tcp_notify_ack_marker *elm;
+
+       elm = SLIST_FIRST(&tp->t_notify_ack);
+       if (SEQ_GEQ(tp->snd_una, elm->notify_snd_una)) {
+               soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_NOTIFY_ACK);
+       }
+}
+
+void
+tcp_get_notify_ack_count(struct tcpcb *tp,
+    struct tcp_notify_ack_complete *retid)
+{
+       struct tcp_notify_ack_marker *elm;
+       size_t  complete = 0;
+
+       SLIST_FOREACH(elm, &tp->t_notify_ack, notify_next) {
+               if (SEQ_GEQ(tp->snd_una, elm->notify_snd_una))
+                       complete++;
+               else
+                       break;
+       }
+       retid->notify_pending = tp->t_notify_ack_count - complete;
+       retid->notify_complete_count = min(TCP_MAX_NOTIFY_ACK, complete);
+}
+
+void
+tcp_get_notify_ack_ids(struct tcpcb *tp,
+    struct tcp_notify_ack_complete *retid)
+{
+       size_t i = 0;
+       struct tcp_notify_ack_marker *elm, *next;
+
+       SLIST_FOREACH_SAFE(elm, &tp->t_notify_ack, notify_next, next) {
+               if (i >= retid->notify_complete_count)
+                       break;
+               if (SEQ_GEQ(tp->snd_una, elm->notify_snd_una)) {
+                       retid->notify_complete_id[i++] = elm->notify_id;
+                       SLIST_REMOVE(&tp->t_notify_ack, elm,
+                           tcp_notify_ack_marker, notify_next);
+                       FREE(elm, M_TEMP);
+                       tp->t_notify_ack_count--;
+               } else {
+                       break;
+               }
+       }
+}
+
+bool
+tcp_notify_ack_active(struct socket *so)
+{
+       if ((SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) &&
+           SOCK_TYPE(so) == SOCK_STREAM) {
+               struct tcpcb *tp = intotcpcb(sotoinpcb(so));
+
+               if (!SLIST_EMPTY(&tp->t_notify_ack)) {
+                       struct tcp_notify_ack_marker *elm;
+                       elm = SLIST_FIRST(&tp->t_notify_ack);
+                       if (SEQ_GEQ(tp->snd_una, elm->notify_snd_una))
+                               return (true);
+               }
+       }
+       return (false);
+}
+
+inline int32_t
+inp_get_sndbytes_allunsent(struct socket *so, u_int32_t th_ack)
+{
+       struct inpcb *inp = sotoinpcb(so);
+       struct tcpcb *tp = intotcpcb(inp);
+
+       if ((so->so_snd.sb_flags & SB_SNDBYTE_CNT) &&
+           so->so_snd.sb_cc > 0) {
+               int32_t unsent, sent;
+               sent = tp->snd_max - th_ack;
+               if (tp->t_flags & TF_SENTFIN)
+                       sent--;
+               unsent = so->so_snd.sb_cc - sent;
+               return (unsent);
+       }
+       return (0);
+}