]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/netinet/tcp_input.c
xnu-2782.1.97.tar.gz
[apple/xnu.git] / bsd / netinet / tcp_input.c
index 7d29a31c24a74e5750ee8563d3508f167e893cab..ab5242853b749bf90c5e8be48a8b954adb43f5a7 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2012 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2014 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -79,7 +79,7 @@
 #include <sys/socketvar.h>
 #include <sys/syslog.h>
 #include <sys/mcache.h>
-
+#include <sys/kasl.h>
 #include <kern/cpu_number.h>   /* before tcp_seq.h, for tcp_random18() */
 
 #include <machine/endian.h>
@@ -88,6 +88,7 @@
 #include <net/if_types.h>
 #include <net/route.h>
 #include <net/ntstat.h>
+#include <net/dlil.h>
 
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
 #include <netinet/tcp_cc.h>
+#include <dev/random/randomdev.h>
 #include <kern/zalloc.h>
 #if INET6
 #include <netinet6/tcp6_var.h>
@@ -136,21 +138,19 @@ struct tcphdr tcp_savetcp;
 
 #include <sys/kdebug.h>
 #include <netinet/lro_ext.h>
+#if MPTCP
+#include <netinet/mptcp_var.h>
+#include <netinet/mptcp.h>
+#include <netinet/mptcp_opt.h> 
+#endif /* MPTCP */
 
 #define DBG_LAYER_BEG          NETDBG_CODE(DBG_NETTCP, 0)
 #define DBG_LAYER_END          NETDBG_CODE(DBG_NETTCP, 2)
 #define DBG_FNC_TCP_INPUT       NETDBG_CODE(DBG_NETTCP, (3 << 8))
 #define DBG_FNC_TCP_NEWCONN     NETDBG_CODE(DBG_NETTCP, (7 << 8))
 
-static int     tcprexmtthresh = 2;
 tcp_cc tcp_ccgen;
 
-#if IPSEC
-extern int ipsec_bypass;
-#endif
-
-extern int32_t total_sbmb_cnt;
-
 struct tcpstat tcpstat;
 
 static int log_in_vain = 0;
@@ -185,16 +185,6 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW | CTLFLAG_LOCKED,
 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW|CTLFLAG_LOCKED, 0,
     "TCP Segment Reassembly Queue");
 
-__private_extern__ int tcp_reass_maxseg = 0;
-SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RW | CTLFLAG_LOCKED,
-    &tcp_reass_maxseg, 0,
-    "Global maximum number of TCP Segments in Reassembly Queue");
-
-__private_extern__ int tcp_reass_qsize = 0;
-SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD | CTLFLAG_LOCKED,
-    &tcp_reass_qsize, 0,
-    "Global number of TCP Segments currently in Reassembly Queue");
-
 static int tcp_reass_overflows = 0;
 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD | CTLFLAG_LOCKED,
     &tcp_reass_overflows, 0,
@@ -241,7 +231,7 @@ u_int32_t tcp_autorcvbuf_max = 512 * 1024;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, autorcvbufmax, CTLFLAG_RW | CTLFLAG_LOCKED,
         &tcp_autorcvbuf_max, 0, "Maximum receive socket buffer size");
 
-int sw_lro = 1;
+int sw_lro = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, lro, CTLFLAG_RW | CTLFLAG_LOCKED,
         &sw_lro, 0, "Used to coalesce TCP packets");
 
@@ -249,35 +239,36 @@ int lrodebug = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, lrodbg, CTLFLAG_RW | CTLFLAG_LOCKED,
         &lrodebug, 0, "Used to debug SW LRO");
 
-int lro_start = 3;
+int lro_start = 4;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, lro_startcnt, CTLFLAG_RW | CTLFLAG_LOCKED,
        &lro_start, 0, "Segments for starting LRO computed as power of 2");
 
 extern int tcp_do_autosendbuf;
 
+int limited_txmt = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, limited_transmit, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &limited_txmt, 0, "Enable limited transmit");
+
+int early_rexmt = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, early_rexmt, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &early_rexmt, 0, "Enable Early Retransmit");
+
+int sack_ackadv = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack_ackadv, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &sack_ackadv, 0, "Use SACK with cumulative ack advancement as a dupack");
+
 #if CONFIG_IFEF_NOWINDOWSCALE
 int tcp_obey_ifef_nowindowscale = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, obey_ifef_nowindowscale, CTLFLAG_RW | CTLFLAG_LOCKED,
        &tcp_obey_ifef_nowindowscale, 0, "");
 #endif
-/* This limit will determine when the receive socket buffer tuning will
- * kick in. Currently it will start when the bw*delay measured in 
- * last RTT is more than half of the current hiwat on the buffer.
- */
-uint32_t tcp_rbuf_hiwat_shift = 1;
-
-/* This limit will determine when the socket buffer will be increased
- * to accommodate an application reading slowly. When the amount of 
- * space left in the buffer is less than one forth of the bw*delay
- * measured in last RTT.
- */
-uint32_t tcp_rbuf_win_shift = 2;
 
 extern int tcp_TCPTV_MIN;
 extern int tcp_acc_iaj_high;
 extern int tcp_acc_iaj_react_limit;
 extern struct zone *tcp_reass_zone;
 
+int tcprexmtthresh = 3;
 
 u_int32_t tcp_now;
 struct timeval tcp_uptime;     /* uptime when tcp_now was last updated */
@@ -291,15 +282,18 @@ static void tcp_dooptions(struct tcpcb *, u_char *, int, struct tcphdr *,
     struct tcpopt *, unsigned int);
 static void     tcp_pulloutofband(struct socket *,
            struct tcphdr *, struct mbuf *, int);
-static int      tcp_reass(struct tcpcb *, struct tcphdr *, int *,
-                               struct mbuf *);
-static void    tcp_xmit_timer(struct tcpcb *, int);
+static int tcp_reass(struct tcpcb *, struct tcphdr *, int *, struct mbuf *,
+    struct ifnet *);
+static void    tcp_xmit_timer(struct tcpcb *, int, u_int32_t, tcp_seq);
 static inline unsigned int tcp_maxmtu(struct rtentry *);
 static inline int tcp_stretch_ack_enable(struct tcpcb *tp);
+static inline void tcp_adaptive_rwtimo_check(struct tcpcb *, int);
 
 #if TRAFFIC_MGT
-static inline void update_iaj_state(struct tcpcb *tp, uint32_t tlen, int reset_size);
-void compute_iaj(struct tcpcb *tp);
+static inline void update_iaj_state(struct tcpcb *tp, uint32_t tlen,
+       int reset_size);
+void compute_iaj(struct tcpcb *tp, int nlropkts, int lro_delay_factor);
+static void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj);
 #endif /* TRAFFIC_MGT */
 
 #if INET6
@@ -314,33 +308,37 @@ static void tcp_sbsnd_trim(struct sockbuf *sbsnd);
 static inline void tcp_sbrcv_tstmp_check(struct tcpcb *tp);
 static inline void tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sb,
        u_int32_t newsize, u_int32_t idealsize);
-
+static void tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th);
+static void tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, 
+       struct tcphdr *th);
+static void tcp_early_rexmt_check(struct tcpcb *tp, struct tcphdr *th);
+static void tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th,
+       struct tcpopt *to);
+/*
+ * Constants used for resizing receive socket buffer 
+ * when timestamps are not supported 
+ */
 #define TCPTV_RCVNOTS_QUANTUM 100
 #define TCP_RCVNOTS_BYTELEVEL 204800
-/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
-#if INET6
-#define ND6_HINT(tp) \
-do { \
-       if ((tp) && (tp)->t_inpcb && \
-           ((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0 && \
-           (tp)->t_inpcb->in6p_route.ro_rt) \
-               nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \
-} while (0)
-#else
-#define ND6_HINT(tp)
-#endif
 
-extern void    add_to_time_wait(struct tcpcb *, uint32_t delay);
-extern void postevent(struct socket *, struct sockbuf *, int);
+/* 
+ * Constants used for limiting early retransmits 
+ * to 10 per minute.
+ */
+#define TCP_EARLY_REXMT_WIN (60 * TCP_RETRANSHZ) /* 60 seconds */
+#define TCP_EARLY_REXMT_LIMIT 10
 
 extern  void    ipfwsyslog( int level, const char *format,...);
-extern int ChkAddressOK( __uint32_t dstaddr, __uint32_t srcaddr );
 extern int fw_verbose;
 
 #if IPFIREWALL
+extern void ipfw_stealth_stats_incr_tcp(void);
+
 #define log_in_vain_log( a ) {            \
         if ( (log_in_vain == 3 ) && (fw_verbose == 2)) {        /* Apple logging, log to ipfw.log */ \
                 ipfwsyslog a ;  \
+        } else if ( (log_in_vain == 4 ) && (fw_verbose == 2)) {   \
+                ipfw_stealth_stats_incr_tcp();                    \
         }                       \
         else log a ;            \
 }
@@ -354,13 +352,13 @@ int tcp_rcvsspktcnt = TCP_RCV_SS_PKTCOUNT;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rcvsspktcnt, CTLFLAG_RW | CTLFLAG_LOCKED,
        &tcp_rcvsspktcnt, 0, "packets to be seen before receiver stretches acks");
 
-#define DELAY_ACK(tp, th) (CC_ALGO(tp)->delay_ack != NULL && CC_ALGO(tp)->delay_ack(tp, th))
+#define DELAY_ACK(tp, th) \
+       (CC_ALGO(tp)->delay_ack != NULL && CC_ALGO(tp)->delay_ack(tp, th))
 
 static int tcp_dropdropablreq(struct socket *head);
 static void tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th);
 
 static void update_base_rtt(struct tcpcb *tp, uint32_t rtt);
-uint32_t get_base_rtt(struct tcpcb *tp);
 void tcp_set_background_cc(struct socket *so);
 void tcp_set_foreground_cc(struct socket *so);
 static void tcp_set_new_cc(struct socket *so, uint16_t cc_index);
@@ -417,33 +415,71 @@ isqrt(unsigned int val) {
        return(g);
 } 
 
+/* 
+* With LRO, roughly estimate the inter arrival time between
+* each sub coalesced packet as an average. Count the delay
+* cur_iaj to be the delay between the last packet received
+* and the first packet of the LRO stream. Due to round off errors
+* cur_iaj may be the same as lro_delay_factor. Averaging has 
+* round off errors too. lro_delay_factor may be close to 0
+* in steady state leading to lower values fed to compute_iaj_meat.
+*/
 void
-compute_iaj(struct tcpcb *tp)
+compute_iaj(struct tcpcb *tp, int nlropkts, int lro_delay_factor)
 {
-       /* When accumulated IAJ reaches MAX_ACC_IAJ in milliseconds, throttle the
-        * receive window to a minimum of MIN_IAJ_WIN packets
+       uint32_t cur_iaj = tcp_now - tp->iaj_rcv_ts;
+       uint32_t timediff = 0;
+
+       if (cur_iaj >= lro_delay_factor) {
+               cur_iaj = cur_iaj - lro_delay_factor;
+       }
+
+       compute_iaj_meat(tp, cur_iaj);
+       
+       if (nlropkts <= 1)
+               return;
+
+       nlropkts--;
+       
+       timediff = lro_delay_factor/nlropkts;
+
+       while (nlropkts > 0) 
+       {
+               compute_iaj_meat(tp, timediff); 
+               nlropkts--;
+       }
+}
+
+static
+void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj)
+{
+       /* When accumulated IAJ reaches MAX_ACC_IAJ in milliseconds, 
+        * throttle the receive window to a minimum of MIN_IAJ_WIN packets
         */
 #define MAX_ACC_IAJ (tcp_acc_iaj_high_thresh + tcp_acc_iaj_react_limit)
+#define IAJ_DIV_SHIFT 4
+#define IAJ_ROUNDUP_CONST (1 << (IAJ_DIV_SHIFT - 1))
 
        uint32_t allowed_iaj, acc_iaj = 0;
-       uint32_t cur_iaj = tcp_now - tp->iaj_rcv_ts;
 
        uint32_t mean, temp;
        int32_t cur_iaj_dev;
+
        cur_iaj_dev = (cur_iaj - tp->avg_iaj);  
        
-       /* Allow a jitter of "allowed_iaj" milliseconds. Some connections may have a
-        * constant jitter more than that. We detect this by using
-        * standard deviation.
+       /* Allow a jitter of "allowed_iaj" milliseconds. Some connections 
+        * may have a constant jitter more than that. We detect this by 
+        * using standard deviation.
         */
        allowed_iaj = tp->avg_iaj + tp->std_dev_iaj;
        if (allowed_iaj < tcp_allowed_iaj)
                allowed_iaj = tcp_allowed_iaj;
 
-       /* Initially when the connection starts, the senders congestion window 
-        * is small. During this period we avoid throttling a connection because
-        * we do not have a good starting point for allowed_iaj. IAJ_IGNORE_PKTCNT
-        * is used to quietly gloss over the first few packets.
+       /* Initially when the connection starts, the senders congestion 
+        * window is small. During this period we avoid throttling a 
+        * connection because we do not have a good starting point for 
+        * allowed_iaj. IAJ_IGNORE_PKTCNT is used to quietly gloss over 
+        * the first few packets.
         */
        if (tp->iaj_pktcnt > IAJ_IGNORE_PKTCNT) {
                if ( cur_iaj <= allowed_iaj ) {
@@ -451,6 +487,7 @@ compute_iaj(struct tcpcb *tp)
                                acc_iaj = tp->acc_iaj - 2;
                        else
                                acc_iaj = 0;
+                               
                } else {
                        acc_iaj = tp->acc_iaj + (cur_iaj - allowed_iaj);
                }
@@ -463,18 +500,25 @@ compute_iaj(struct tcpcb *tp)
        /* Compute weighted average where the history has a weight of
         * 15 out of 16 and the current value has a weight of 1 out of 16. 
         * This will make the short-term measurements have more weight.
+        *
+        * The addition of 8 will help to round-up the value 
+        * instead of round-down
         */
-       tp->avg_iaj = (((tp->avg_iaj << 4) - tp->avg_iaj) + cur_iaj) >> 4;
+       tp->avg_iaj = (((tp->avg_iaj << IAJ_DIV_SHIFT) - tp->avg_iaj) 
+               + cur_iaj + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT;
 
        /* Compute Root-mean-square of deviation where mean is a weighted
-        * average as described above
+        * average as described above
         */
        temp = tp->std_dev_iaj * tp->std_dev_iaj;
-       mean = (((temp << 4) - temp) + (cur_iaj_dev * cur_iaj_dev)) >> 4;
+       mean = (((temp << IAJ_DIV_SHIFT) - temp) 
+               + (cur_iaj_dev * cur_iaj_dev) 
+               + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT;
        
        tp->std_dev_iaj = isqrt(mean);
 
-       DTRACE_TCP3(iaj, struct tcpcb *, tp, uint32_t, cur_iaj, uint32_t, allowed_iaj);
+       DTRACE_TCP3(iaj, struct tcpcb *, tp, uint32_t, cur_iaj, 
+               uint32_t, allowed_iaj);
 
        return;
 }
@@ -509,19 +553,23 @@ tcp_bwmeas_check(struct tcpcb *tp)
 }
 
 static int
-tcp_reass(tp, th, tlenp, m)
-       register struct tcpcb *tp;
-       register struct tcphdr *th;
-       int *tlenp;
-       struct mbuf *m;
+tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m,
+    struct ifnet *ifp)
 {
        struct tseg_qent *q;
        struct tseg_qent *p = NULL;
        struct tseg_qent *nq;
        struct tseg_qent *te = NULL;
-       struct socket *so = tp->t_inpcb->inp_socket;
-       int flags;
+       struct inpcb *inp = tp->t_inpcb;
+       struct socket *so = inp->inp_socket;
+       int flags = 0;
        int dowakeup = 0;
+       struct mbuf *oodata = NULL;
+       int copy_oodata = 0;
+       u_int16_t qlimit;
+       boolean_t cell = IFNET_IS_CELLULAR(ifp);
+       boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp));
+       boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp));
 
        /*
         * Call with th==0 after become established to
@@ -530,21 +578,12 @@ tcp_reass(tp, th, tlenp, m)
        if (th == NULL)
                goto present;
        
-       /* If the reassembly queue already has entries or if we are going to add 
-        * a new one, then the connection has reached a loss state. 
+       /*
+        * If the reassembly queue already has entries or if we are going 
+        * to add a new one, then the connection has reached a loss state. 
         * Reset the stretch-ack algorithm at this point.
         */
-       if ((tp->t_flags & TF_STRETCHACK) != 0)
-               tcp_reset_stretch_ack(tp);
-
-       /* When the connection reaches a loss state, we need to send more acks
-        * for a period of time so that the sender's congestion window will
-        * open. Wait until we see some packets on the connection before 
-        * stretching acks again.
-        */
-       tp->t_flagsext |= TF_RCVUNACK_WAITSS;
-       tp->rcv_waitforss = 0;
-
+       tcp_reset_stretch_ack(tp);
 
 #if TRAFFIC_MGT
        if (tp->acc_iaj > 0)
@@ -558,8 +597,10 @@ tcp_reass(tp, th, tlenp, m)
         * queue.  Always keep one global queue entry spare to be able to
         * process the missing segment.
         */
+       qlimit = min(max(100, so->so_rcv.sb_hiwat >> 10),
+           tcp_autorcvbuf_max >> 10); 
        if (th->th_seq != tp->rcv_nxt &&
-           tcp_reass_qsize + 1 >= tcp_reass_maxseg) {
+           (tp->t_reassqlen + 1) >= qlimit) {
                tcp_reass_overflows++;
                tcpstat.tcps_rcvmemdrop++;
                m_freem(m);
@@ -568,13 +609,13 @@ tcp_reass(tp, th, tlenp, m)
        }
 
        /* Allocate a new queue entry. If we can't, just drop the pkt. XXX */
-       te = (struct tseg_qent *) zalloc_noblock(tcp_reass_zone);
+       te = (struct tseg_qent *) zalloc(tcp_reass_zone);
        if (te == NULL) {
                tcpstat.tcps_rcvmemdrop++;
                m_freem(m);
                return (0);
        }
-       tcp_reass_qsize++;
+       tp->t_reassqlen++;
 
        /*
         * Find a segment which begins after this one does.
@@ -599,21 +640,26 @@ tcp_reass(tp, th, tlenp, m)
                                tcpstat.tcps_rcvduppack++;
                                tcpstat.tcps_rcvdupbyte += *tlenp;
                                if (nstat_collect) {
-                                       nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, *tlenp, NSTAT_RX_FLAG_DUPLICATE);
-                                       locked_add_64(&tp->t_inpcb->inp_stat->rxpackets, 1);
-                                       locked_add_64(&tp->t_inpcb->inp_stat->rxbytes, *tlenp);
+                                       nstat_route_rx(inp->inp_route.ro_rt,
+                                           1, *tlenp,
+                                           NSTAT_RX_FLAG_DUPLICATE);
+                                       INP_ADD_STAT(inp, cell, wifi, wired,
+                                           rxpackets, 1);
+                                       INP_ADD_STAT(inp, cell, wifi, wired,
+                                           rxbytes, *tlenp);
                                        tp->t_stat.rxduplicatebytes += *tlenp;
                                }
                                m_freem(m);
                                zfree(tcp_reass_zone, te);
-                               tcp_reass_qsize--;
+                               te = NULL;
+                               tp->t_reassqlen--;
                                /*
                                 * Try to present any queued data
                                 * at the left window edge to the user.
                                 * This is needed after the 3-WHS
                                 * completes.
                                 */
-                               goto present;   /* ??? */
+                               goto present;
                        }
                        m_adj(m, i);
                        *tlenp -= i;
@@ -623,9 +669,10 @@ tcp_reass(tp, th, tlenp, m)
        tcpstat.tcps_rcvoopack++;
        tcpstat.tcps_rcvoobyte += *tlenp;
        if (nstat_collect) {
-               nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, *tlenp, NSTAT_RX_FLAG_OUT_OF_ORDER);
-               locked_add_64(&tp->t_inpcb->inp_stat->rxpackets, 1);
-               locked_add_64(&tp->t_inpcb->inp_stat->rxbytes, *tlenp);
+               nstat_route_rx(inp->inp_route.ro_rt, 1, *tlenp,
+                   NSTAT_RX_FLAG_OUT_OF_ORDER);
+               INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1);
+               INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, *tlenp);
                tp->t_stat.rxoutoforderbytes += *tlenp;
        }
 
@@ -648,7 +695,7 @@ tcp_reass(tp, th, tlenp, m)
                LIST_REMOVE(q, tqe_q);
                m_freem(q->tqe_m);
                zfree(tcp_reass_zone, q);
-               tcp_reass_qsize--;
+               tp->t_reassqlen--;
                q = nq;
        }
 
@@ -663,6 +710,15 @@ tcp_reass(tp, th, tlenp, m)
                LIST_INSERT_AFTER(p, te, tqe_q);
        }
 
+       /* 
+        * New out-of-order data exists, and is pointed to by
+        * queue entry te. Set copy_oodata to 1 so out-of-order data 
+        * can be copied off to sockbuf after in-order data 
+        * is copied off.
+        */
+       if (!(so->so_state & SS_CANTRCVMORE))
+               copy_oodata = 1;
+
 present:
        /*
         * Present data to user, advancing rcv_nxt through
@@ -674,58 +730,101 @@ present:
        if (!q || q->tqe_th->th_seq != tp->rcv_nxt) {
                /* Stop using LRO once out of order packets arrive */
                if (tp->t_flagsext & TF_LRO_OFFLOADED) {
-                       tcp_lro_remove_state(tp->t_inpcb->inp_laddr,
-                               tp->t_inpcb->inp_faddr,
+                       tcp_lro_remove_state(inp->inp_laddr, inp->inp_faddr,
                                th->th_dport, th->th_sport);
                        tp->t_flagsext &= ~TF_LRO_OFFLOADED;    
                }
+
+               /*
+                * continue processing if out-of-order data 
+                * can be delivered
+                */
+               if (q && (so->so_flags & SOF_ENABLE_MSGS))
+                       goto msg_unordered_delivery;
+
                return (0);
-       }       
+       }
+
+       /* lost packet was recovered, so ooo data can be returned */
+       tcpstat.tcps_recovered_pkts++;
+
        do {
                tp->rcv_nxt += q->tqe_len;
                flags = q->tqe_th->th_flags & TH_FIN;
                nq = LIST_NEXT(q, tqe_q);
                LIST_REMOVE(q, tqe_q);
-               if (so->so_state & SS_CANTRCVMORE)
+               if (so->so_state & SS_CANTRCVMORE) {
                        m_freem(q->tqe_m);
-               else {
+               else {
                        so_recv_data_stat(so, q->tqe_m, 0); /* XXXX */
-                       if (sbappendstream(&so->so_rcv, q->tqe_m))
+                       if (so->so_flags & SOF_ENABLE_MSGS) {
+                               /* 
+                                * Append the inorder data as a message to the 
+                                * receive socket buffer. Also check to see if 
+                                * the data we are about to deliver is the same 
+                                * data that we wanted to pass up to the user 
+                                * out of order. If so, reset copy_oodata -- 
+                                * the received data filled a gap, and
+                                * is now in order!
+                                */
+                               if (q == te)
+                                       copy_oodata = 0;
+                       }
+                       if (sbappendstream_rcvdemux(so, q->tqe_m, 
+                           q->tqe_th->th_seq - (tp->irs + 1), 0))
                                dowakeup = 1;
                        if (tp->t_flagsext & TF_LRO_OFFLOADED) {        
                                tcp_update_lro_seq(tp->rcv_nxt, 
-                                tp->t_inpcb->inp_laddr,
-                                tp->t_inpcb->inp_faddr, th->th_dport, th->th_sport);
+                                inp->inp_laddr, inp->inp_faddr,
+                                th->th_dport, th->th_sport);
                        }
                }
                zfree(tcp_reass_zone, q);
-               tcp_reass_qsize--;
+               tp->t_reassqlen--;
                q = nq;
        } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
-       ND6_HINT(tp);
 
 #if INET6
-       if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
+       if ((inp->inp_vflag & INP_IPV6) != 0) {
        
                KERNEL_DEBUG(DBG_LAYER_BEG,
-                    ((tp->t_inpcb->inp_fport << 16) | tp->t_inpcb->inp_lport),
-                    (((tp->t_inpcb->in6p_laddr.s6_addr16[0] & 0xffff) << 16) |
-                     (tp->t_inpcb->in6p_faddr.s6_addr16[0] & 0xffff)),
+                    ((inp->inp_fport << 16) | inp->inp_lport),
+                    (((inp->in6p_laddr.s6_addr16[0] & 0xffff) << 16) |
+                     (inp->in6p_faddr.s6_addr16[0] & 0xffff)),
                     0,0,0);
        }
        else
 #endif
        {
                KERNEL_DEBUG(DBG_LAYER_BEG,
-                    ((tp->t_inpcb->inp_fport << 16) | tp->t_inpcb->inp_lport),
-                    (((tp->t_inpcb->inp_laddr.s_addr & 0xffff) << 16) |
-                     (tp->t_inpcb->inp_faddr.s_addr & 0xffff)),
+                    ((inp->inp_fport << 16) | inp->inp_lport),
+                    (((inp->inp_laddr.s_addr & 0xffff) << 16) |
+                     (inp->inp_faddr.s_addr & 0xffff)),
                     0,0,0);
        }
+
+msg_unordered_delivery:
+       /* Deliver out-of-order data as a message */
+       if (te && (so->so_flags & SOF_ENABLE_MSGS) && copy_oodata && te->tqe_len) {
+               /* 
+                * make a copy of the mbuf to be delivered up to 
+                * the user, and add it to the sockbuf
+                */
+               oodata = m_copym(te->tqe_m, 0, M_COPYALL, M_DONTWAIT);
+               if (oodata != NULL) {
+                       if (sbappendmsgstream_rcv(&so->so_rcv, oodata, 
+                               te->tqe_th->th_seq - (tp->irs + 1), 1)) {
+                               dowakeup = 1;
+                               tcpstat.tcps_msg_unopkts++;
+                       } else {
+                               tcpstat.tcps_msg_unoappendfail++;
+                       }
+               }
+       }
+
        if (dowakeup)
                sorwakeup(so); /* done with socket lock held */
        return (flags);
-
 }
 
 /*
@@ -745,12 +844,37 @@ tcp_reduce_congestion_window(
        ENTER_FASTRECOVERY(tp);
        tp->snd_recover = tp->snd_max;
        tp->t_timer[TCPT_REXMT] = 0;
+       tp->t_timer[TCPT_PTO] = 0;
        tp->t_rtttime = 0;
-       tp->ecn_flags |= TE_SENDCWR;
        tp->snd_cwnd = tp->snd_ssthresh +
                 tp->t_maxseg * tcprexmtthresh;
 }
 
+/*
+ * The application wants to get an event if there
+ * is a stall during read. Set the initial keepalive
+ * timeout to be equal to twice RTO.
+ */
+static inline void
+tcp_adaptive_rwtimo_check(struct tcpcb *tp, int tlen) 
+{
+       if (tp->t_adaptive_rtimo > 0 && tlen > 0 &&
+               tp->t_state == TCPS_ESTABLISHED) {
+               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, 
+                       (TCP_REXMTVAL(tp) << 1));
+               tp->t_flagsext |= TF_DETECT_READSTALL;
+               tp->t_rtimo_probes = 0;
+       }
+}
+
+inline void
+tcp_keepalive_reset(struct tcpcb *tp)
+{
+       tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, 
+               TCP_CONN_KEEPIDLE(tp));
+       tp->t_flagsext &= ~(TF_DETECT_READSTALL);
+       tp->t_rtimo_probes = 0;
+}
 
 /*
  * TCP input routine, follows pages 65-76 of the
@@ -762,8 +886,8 @@ tcp6_input(struct mbuf **mp, int *offp, int proto)
 {
 #pragma unused(proto)
        register struct mbuf *m = *mp;
-       struct in6_ifaddr *ia6;
-       struct ifnet *ifp = ((m->m_flags & M_PKTHDR) && m->m_pkthdr.rcvif != NULL) ? m->m_pkthdr.rcvif: NULL;
+       uint32_t ia6_flags;
+       struct ifnet *ifp = m->m_pkthdr.rcvif;
 
        IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE);
 
@@ -774,26 +898,19 @@ tcp6_input(struct mbuf **mp, int *offp, int proto)
         * draft-itojun-ipv6-tcp-to-anycast
         * better place to put this in?
         */
-       ia6 = ip6_getdstifaddr(m);
-       if (ia6 != NULL) {
-               IFA_LOCK_SPIN(&ia6->ia_ifa);
-               if (ia6->ia6_flags & IN6_IFF_ANYCAST) {
+       if (ip6_getdstifaddr_info(m, NULL, &ia6_flags) == 0) {
+               if (ia6_flags & IN6_IFF_ANYCAST) {
                        struct ip6_hdr *ip6;
 
-                       IFA_UNLOCK(&ia6->ia_ifa);
-                       IFA_REMREF(&ia6->ia_ifa);
                        ip6 = mtod(m, struct ip6_hdr *);
                        icmp6_error(m, ICMP6_DST_UNREACH,
                            ICMP6_DST_UNREACH_ADDR,
                            (caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
-                               
-                       if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->icmp6unreach, 1);
-                               
+
+                       IF_TCP_STATINC(ifp, icmp6unreach);
+
                        return (IPPROTO_DONE);
                }
-               IFA_UNLOCK(&ia6->ia_ifa);
-               IFA_REMREF(&ia6->ia_ifa);
        }
 
        tcp_input(m, *offp);
@@ -823,15 +940,16 @@ tcp_cansbgrow(struct sockbuf *sb)
        if ((total_sbmb_cnt < mblim) &&
                (sb->sb_hiwat < sbspacelim)) {
                return(1);
+       } else {
+               OSIncrementAtomic64(&sbmb_limreached);
        }
        return(0);
 }
 
-void
-tcp_sbrcv_reserve(struct tcpcb *tp,
-       struct sockbuf *sbrcv,
-       u_int32_t newsize,
-       u_int32_t idealsize) {
+static void
+tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sbrcv,
+       u_int32_t newsize, u_int32_t idealsize)
+{
 
        /* newsize should not exceed max */
        newsize = min(newsize, tcp_autorcvbuf_max);
@@ -866,10 +984,23 @@ static void
 tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sbrcv, 
        struct tcpopt *to, u_int32_t pktlen) {
        
+       /*
+        * Do not grow the receive socket buffer if
+        * - auto resizing is disabled, globally or on this socket
+        * - the high water mark already reached the maximum
+        * - the stream is in background and receive side is being 
+        * throttled
+        * - if there are segments in reassembly queue indicating loss,
+        * do not need to increase recv window during recovery as more 
+        * data is not going to be sent. A duplicate ack sent during
+        * recovery should not change the receive window
+        */
        if (tcp_do_autorcvbuf == 0 ||
                (sbrcv->sb_flags & SB_AUTOSIZE) == 0 ||
                tcp_cansbgrow(sbrcv) == 0 ||
-               sbrcv->sb_hiwat >= tcp_autorcvbuf_max) {
+               sbrcv->sb_hiwat >= tcp_autorcvbuf_max ||
+               (tp->t_flagsext & TF_RECV_THROTTLE) ||
+               !LIST_EMPTY(&tp->t_segq)) {
                /* Can not resize the socket buffer, just return */
                goto out;
        }
@@ -882,14 +1013,13 @@ tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sbrcv,
                goto out;
        }
 
-       if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP)) !=
-               (TF_REQ_TSTMP | TF_RCVD_TSTMP)) {
+       if (!TSTMP_SUPPORTED(tp)) {
                /*
                 * Timestamp option is not supported on this connection.
                 * If the connection reached a state to indicate that
                 * the receive socket buffer needs to grow, increase
-                * the high water mark. 
-                */ 
+                * the high water mark.
+                */
                if (TSTMP_GEQ(tcp_now, 
                        tp->rfbuf_ts + TCPTV_RCVNOTS_QUANTUM)) {
                        if (tp->rfbuf_cnt >= TCP_RCVNOTS_BYTELEVEL) {
@@ -900,38 +1030,46 @@ tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sbrcv,
                } else {
                        tp->rfbuf_cnt += pktlen;
                        return;
-               }       
+               }
        } else if (to->to_tsecr != 0) {
-               /* If the timestamp shows that one RTT has
+               /*
+                * If the timestamp shows that one RTT has
                 * completed, we can stop counting the
                 * bytes. Here we consider increasing
-                * the socket buffer if it fits the following 
-                * criteria: 
-                * 1. the bandwidth measured in last rtt, is more 
-                * than half of sb_hiwat, this will help to scale the
-                * buffer according to the bandwidth on the link.
-                * 2. the space left in sbrcv is less than 
-                * one forth of the bandwidth measured in last rtt, this
-                * will help to accommodate an application reading slowly.
+                * the socket buffer if the bandwidth measured in
+                * last rtt, is more than half of sb_hiwat, this will
+                * help to scale the buffer according to the bandwidth
+                * on the link.
                 */
                if (TSTMP_GEQ(to->to_tsecr, tp->rfbuf_ts)) {
-                       if ((tp->rfbuf_cnt > (sbrcv->sb_hiwat -
-                               (sbrcv->sb_hiwat >> tcp_rbuf_hiwat_shift)) ||
-                               (sbrcv->sb_hiwat - sbrcv->sb_cc) <
-                               (tp->rfbuf_cnt >> tcp_rbuf_win_shift))) {
-                               u_int32_t rcvbuf_inc; 
+                       if (tp->rfbuf_cnt > (sbrcv->sb_hiwat -
+                               (sbrcv->sb_hiwat >> 1))) {
+                               int32_t rcvbuf_inc, min_incr;
                                /*
-                                * Increment the receive window by a multiple of
-                                * maximum sized segments. This will prevent a 
-                                * connection from sending smaller segments on 
-                                * wire if it is limited by the receive window.
+                                * Increment the receive window by a
+                                * multiple of maximum sized segments.
+                                * This will prevent a connection from 
+                                * sending smaller segments on wire if it
+                                * is limited by the receive window.
                                 *
-                                * Set the ideal size based on current bandwidth 
-                                * measurements. We set the ideal size on receiv
-                                * socket buffer to be twice the bandwidth delay 
-                                * product.
+                                * Set the ideal size based on current
+                                * bandwidth measurements. We set th
+                                * ideal size on receive socket buffer to
+                                * be twice the bandwidth delay product.
                                 */
-                               rcvbuf_inc = tp->t_maxseg << tcp_autorcvbuf_inc_shift;
+                               rcvbuf_inc = (tp->rfbuf_cnt << 1)
+                                   - sbrcv->sb_hiwat;
+
+                               /*
+                                * Make the increment equal to 8 segments
+                                * at least
+                                */
+                               min_incr = tp->t_maxseg << tcp_autorcvbuf_inc_shift;
+                               if (rcvbuf_inc < min_incr)
+                                   rcvbuf_inc = min_incr;
+
+                               rcvbuf_inc = 
+                                   (rcvbuf_inc / tp->t_maxseg) * tp->t_maxseg;
                                tcp_sbrcv_reserve(tp, sbrcv,
                                        sbrcv->sb_hiwat + rcvbuf_inc, 
                                        (tp->rfbuf_cnt * 2));
@@ -1052,11 +1190,13 @@ tcp_sbrcv_tstmp_check(struct tcpcb *tp) {
  * tcp_rcvsspktcnt to cover slow-start and tcp_maxrcvidle to identify idle 
  * state.
  */
- static inline int
- tcp_stretch_ack_enable(struct tcpcb *tp) {
-       if (tp->rcv_by_unackwin >= (maxseg_unacked * tp->t_maxseg) &&
+static inline int
+tcp_stretch_ack_enable(struct tcpcb *tp)
+{
+       if (!(tp->t_flagsext & (TF_NOSTRETCHACK|TF_DISABLE_STRETCHACK)) &&
+               tp->rcv_by_unackwin >= (maxseg_unacked * tp->t_maxseg) &&
                TSTMP_GT(tp->rcv_unackwin + tcp_maxrcvidle, tcp_now) &&
-               (((tp->t_flagsext & TF_RCVUNACK_WAITSS) == 0) ||
+               (!(tp->t_flagsext & TF_RCVUNACK_WAITSS) ||
                (tp->rcv_waitforss >= tcp_rcvsspktcnt))) {
                return(1);
        }
@@ -1064,7 +1204,8 @@ tcp_sbrcv_tstmp_check(struct tcpcb *tp) {
        return(0);
 }
 
-/* Reset the state related to stretch-ack algorithm. This will make
+/*
+ * Reset the state related to stretch-ack algorithm. This will make
  * the receiver generate an ack every other packet. The receiver
  * will start re-evaluating the rate at which packets come to decide 
  * if it can benefit by lowering the ack traffic.
@@ -1075,6 +1216,270 @@ tcp_reset_stretch_ack(struct tcpcb *tp)
        tp->t_flags &= ~(TF_STRETCHACK);
        tp->rcv_by_unackwin = 0;
        tp->rcv_unackwin = tcp_now + tcp_rcvunackwin;
+
+       /*
+        * When there is packet loss or packet re-ordering or CWR due to
+        * ECN, the sender's congestion window is reduced. In these states,
+        * generate an ack for every other packet for some time to allow
+        * the sender's congestion window to grow. 
+        */
+       tp->t_flagsext |= TF_RCVUNACK_WAITSS;
+       tp->rcv_waitforss = 0;
+}
+
+/*
+ * The last packet was a retransmission, check if this ack 
+ * indicates that the retransmission was spurious.
+ * 
+ * If the connection supports timestamps, we could use it to
+ * detect if the last retransmit was not needed. Otherwise,
+ * we check if the ACK arrived within RTT/2 window, then it 
+ * was a mistake to do the retransmit in the first place.
+ *
+ * This function will return 1 if it is a spurious retransmit, 
+ * 0 otherwise. 
+ */
+int
+tcp_detect_bad_rexmt(struct tcpcb *tp, struct tcphdr *th, 
+       struct tcpopt *to, u_int32_t rxtime)
+{
+       int32_t tdiff, bad_rexmt_win;
+       bad_rexmt_win = (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
+
+       /* If the ack has ECN CE bit, then cwnd has to be adjusted */
+       if ((tp->ecn_flags & (TE_ECN_ON)) == (TE_ECN_ON)
+           && (th->th_flags & TH_ECE))
+               return (0);
+       if (TSTMP_SUPPORTED(tp)) {
+               if (rxtime > 0 && (to->to_flags & TOF_TS)
+                   && to->to_tsecr != 0 
+                   && TSTMP_LT(to->to_tsecr, rxtime))
+                   return (1);
+       } else {
+               if ((tp->t_rxtshift == 1 
+                   || (tp->t_flagsext & TF_SENT_TLPROBE))
+                   && rxtime > 0) {
+                       tdiff = (int32_t)(tcp_now - rxtime);
+                       if (tdiff < bad_rexmt_win)
+                               return(1);
+               }
+       }
+       return(0);
+}
+
+
+/*
+ * Restore congestion window state if a spurious timeout
+ * was detected.
+ */
+static void
+tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th)
+{
+       if (TSTMP_SUPPORTED(tp)) {
+               u_int32_t fsize, acked;
+               fsize = tp->snd_max - th->th_ack;
+               acked = BYTES_ACKED(th, tp);
+
+               /*
+                * Implement bad retransmit recovery as
+                * described in RFC 4015.
+                */
+               tp->snd_ssthresh = tp->snd_ssthresh_prev;
+
+               /* Initialize cwnd to the initial window */
+               if (CC_ALGO(tp)->cwnd_init != NULL)
+                       CC_ALGO(tp)->cwnd_init(tp);
+
+               tp->snd_cwnd = fsize + min(acked, tp->snd_cwnd);
+               
+       } else {
+               tp->snd_cwnd = tp->snd_cwnd_prev;
+               tp->snd_ssthresh = tp->snd_ssthresh_prev;
+               if (tp->t_flags & TF_WASFRECOVERY)
+                       ENTER_FASTRECOVERY(tp);
+       }
+       tp->snd_cwnd = max(tp->snd_cwnd, TCP_CC_CWND_INIT_BYTES);
+       tp->snd_recover = tp->snd_recover_prev;
+       tp->snd_nxt = tp->snd_max;
+       tp->t_rxtshift = 0;
+       tp->t_rxtstart = 0;
+
+       /* Fix send socket buffer to reflect the change in cwnd */
+       tcp_bad_rexmt_fix_sndbuf(tp);
+
+       /*
+        * This RTT might reflect the extra delay induced 
+        * by the network. Skip using this sample for RTO
+        * calculation and mark the connection so we can
+        * recompute RTT when the next eligible sample is
+        * found.
+        */
+       tp->t_flagsext |= TF_RECOMPUTE_RTT;
+       tp->t_badrexmt_time = tcp_now;
+       tp->t_rtttime = 0;
+}
+
+/*
+ * If the previous packet was sent in retransmission timer, and it was
+ * not needed, then restore the congestion window to the state before that
+ * transmission.
+ *
+ * If the last packet was sent in tail loss probe timeout, check if that
+ * recovered the last packet. If so, that will indicate a real loss and
+ * the congestion window needs to be lowered.
+ */
+static void
+tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to)
+{
+       if (tp->t_rxtshift > 0 &&
+           tcp_detect_bad_rexmt(tp, th, to, tp->t_rxtstart)) {
+               ++tcpstat.tcps_sndrexmitbad;
+               tcp_bad_rexmt_restore_state(tp, th);
+               tcp_ccdbg_trace(tp, th, TCP_CC_BAD_REXMT_RECOVERY);
+       } else if ((tp->t_flagsext & TF_SENT_TLPROBE)
+           && tp->t_tlphighrxt > 0
+           && SEQ_GEQ(th->th_ack, tp->t_tlphighrxt)
+           && !tcp_detect_bad_rexmt(tp, th, to, tp->t_tlpstart)) {
+               /*
+                * The tail loss probe recovered the last packet and 
+                * we need to adjust the congestion window to take
+                * this loss into account.
+                */
+               ++tcpstat.tcps_tlp_recoverlastpkt;
+               if (!IN_FASTRECOVERY(tp)) {
+                       tcp_reduce_congestion_window(tp);
+                       EXIT_FASTRECOVERY(tp);
+               }
+               tcp_ccdbg_trace(tp, th, TCP_CC_TLP_RECOVER_LASTPACKET);
+       }
+
+       tp->t_flagsext &= ~(TF_SENT_TLPROBE);
+       tp->t_tlphighrxt = 0;
+       tp->t_tlpstart = 0;
+
+       /*
+        * check if the latest ack was for a segment sent during PMTU
+        * blackhole detection. If the timestamp on the ack is before
+        * PMTU blackhole detection, then revert the size of the max
+        * segment to previous size.
+        */
+       if (tp->t_rxtshift > 0 && (tp->t_flags & TF_BLACKHOLE) &&
+           tp->t_pmtud_start_ts > 0 && TSTMP_SUPPORTED(tp)) {
+               if ((to->to_flags & TOF_TS) && to->to_tsecr != 0 
+                   && TSTMP_LT(to->to_tsecr, tp->t_pmtud_start_ts)) {
+                       tcp_pmtud_revert_segment_size(tp);
+               }
+       }
+       if (tp->t_pmtud_start_ts > 0)
+               tp->t_pmtud_start_ts = 0;
+}
+
+/*
+ * Check if early retransmit can be attempted according to RFC 5827.
+ *
+ * If packet reordering is detected on a connection, fast recovery will
+ * be delayed until it is clear that the packet was lost and not reordered.
+ * But reordering detection is done only when SACK is enabled.
+ *
+ * On connections that do not support SACK, there is a limit on the number
+ * of early retransmits that can be done per minute. This limit is needed
+ * to make sure that too many packets are not retransmitted when there is
+ * packet reordering.
+ */
+static void
+tcp_early_rexmt_check (struct tcpcb *tp, struct tcphdr *th)
+{
+       u_int32_t obytes, snd_off;
+       int32_t snd_len;
+       struct socket *so = tp->t_inpcb->inp_socket;
+
+       if (early_rexmt && (SACK_ENABLED(tp) ||
+           tp->t_early_rexmt_count < TCP_EARLY_REXMT_LIMIT) &&
+           SEQ_GT(tp->snd_max, tp->snd_una) &&
+           (tp->t_dupacks == 1 || 
+           (SACK_ENABLED(tp) && 
+           !TAILQ_EMPTY(&tp->snd_holes)))) {
+               /*
+                * If there are only a few outstanding 
+                * segments on the connection, we might need
+                * to lower the retransmit threshold. This
+                * will allow us to do Early Retransmit as 
+                * described in RFC 5827.
+                */
+               if (SACK_ENABLED(tp) && 
+                   !TAILQ_EMPTY(&tp->snd_holes)) {
+                       obytes = (tp->snd_max - tp->snd_fack) +
+                               tp->sackhint.sack_bytes_rexmit;
+               } else {
+                       obytes = (tp->snd_max - tp->snd_una);   
+               }
+
+               /*
+                * In order to lower retransmit threshold the 
+                * following two conditions must be met.
+                * 1. the amount of outstanding data is less 
+                * than 4*SMSS bytes
+                * 2. there is no unsent data ready for 
+                * transmission or the advertised window 
+                * will limit sending new segments.
+                */
+               snd_off = tp->snd_max - tp->snd_una;
+               snd_len = min(so->so_snd.sb_cc, tp->snd_wnd) - snd_off;
+               if (obytes < (tp->t_maxseg << 2) && 
+                   snd_len <= 0) {
+                       u_int32_t osegs;
+
+                       osegs = obytes / tp->t_maxseg;
+                       if ((osegs * tp->t_maxseg) < obytes)
+                               osegs++;
+
+                       /* 
+                        * Since the connection might have already 
+                        * received some dupacks, we add them to
+                        * to the outstanding segments count to get
+                        * the correct retransmit threshold.
+                        *
+                        * By checking for early retransmit after 
+                        * receiving some duplicate acks when SACK
+                        * is supported, the connection will 
+                        * enter fast recovery even if multiple 
+                        * segments are lost in the same window.
+                        */
+                       osegs += tp->t_dupacks;
+                       if (osegs < 4) {
+                               tp->t_rexmtthresh = 
+                                   ((osegs - 1) > 1) ? (osegs - 1) : 1;
+                               tp->t_rexmtthresh =
+                                   min(tp->t_rexmtthresh, tcprexmtthresh);
+                               tp->t_rexmtthresh =
+                                   max(tp->t_rexmtthresh, tp->t_dupacks);
+
+                               if (tp->t_early_rexmt_count == 0)
+                                       tp->t_early_rexmt_win = tcp_now;
+
+                               if (tp->t_flagsext & TF_SENT_TLPROBE) {
+                                       tcpstat.tcps_tlp_recovery++;
+                                       tcp_ccdbg_trace(tp, th,
+                                           TCP_CC_TLP_RECOVERY);
+                               } else {
+                                       tcpstat.tcps_early_rexmt++;
+                                       tp->t_early_rexmt_count++;
+                                       tcp_ccdbg_trace(tp, th,
+                                           TCP_CC_EARLY_RETRANSMIT);
+                               }
+                       }
+               }
+       }
+
+       /*
+        * If we ever sent a TLP probe, the acknowledgement will trigger
+        * early retransmit because the value of snd_fack will be close
+        * to snd_max. This will take care of adjustments to the
+        * congestion window. So we can reset TF_SENT_PROBE flag.
+        */
+       tp->t_flagsext &= ~(TF_SENT_TLPROBE);
+       tp->t_tlphighrxt = 0;
+       tp->t_tlpstart = 0;
 }
 
 void
@@ -1084,11 +1489,10 @@ tcp_input(m, off0)
 {
        register struct tcphdr *th;
        register struct ip *ip = NULL;
-       register struct ipovly *ipov;
        register struct inpcb *inp;
        u_char *optp = NULL;
        int optlen = 0;
-       int len, tlen, off;
+       int tlen, off;
        int drop_hdrlen;
        register struct tcpcb *tp = 0;
        register int thflags;
@@ -1100,7 +1504,7 @@ tcp_input(m, off0)
 #endif
        int dropsocket = 0;
        int iss = 0, nosock = 0; 
-       u_int32_t tiwin;
+       u_int32_t tiwin, sack_bytes_acked = 0;
        struct tcpopt to;               /* options in this segment */
        struct sockaddr_in *next_hop = NULL;
 #if TCPDEBUG
@@ -1108,22 +1512,27 @@ tcp_input(m, off0)
 #endif
        struct m_tag *fwd_tag;
        u_char ip_ecn = IPTOS_ECN_NOTECT;
-       unsigned int ifscope, nocell = 0;
+       unsigned int ifscope;
        uint8_t isconnected, isdisconnected;
-       struct ifnet *ifp = ((m->m_flags & M_PKTHDR) && m->m_pkthdr.rcvif != NULL) ? m->m_pkthdr.rcvif: NULL;
-       int nlropkts = m->m_pkthdr.lro_npkts;
-       int mauxf_sw_lro_pkt = (m->m_pkthdr.aux_flags & MAUXF_SW_LRO_PKT) ? 1 : 0;
-       int turnoff_lro = 0;
+       struct ifnet *ifp = m->m_pkthdr.rcvif;
+       int pktf_sw_lro_pkt = (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) ? 1 : 0;
+       int nlropkts = (pktf_sw_lro_pkt == 1) ? m->m_pkthdr.lro_npkts : 1;
+       int turnoff_lro = 0, win;
+#if MPTCP
+       struct mptcb *mp_tp = NULL;
+       uint16_t mptcp_csum = 0;
+#endif /* MPTCP */
+       boolean_t cell = IFNET_IS_CELLULAR(ifp);
+       boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp));
+       boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp));
+       struct tcp_respond_args tra;
+
 #define TCP_INC_VAR(stat, npkts) do {                  \
-       if (mauxf_sw_lro_pkt) { \
-               stat += npkts;                                  \
-       } else {                                                \
-               stat++;                                         \
-       }                                                       \
+               stat += npkts;                          \
 } while (0)
 
        TCP_INC_VAR(tcpstat.tcps_rcvtotal, nlropkts);
-       
+
        /* Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. */
        if (!SLIST_EMPTY(&m->m_pkthdr.tags)) {
                fwd_tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID,
@@ -1132,19 +1541,20 @@ tcp_input(m, off0)
                fwd_tag = NULL;
        }
        if (fwd_tag != NULL) {
-               struct ip_fwd_tag *ipfwd_tag = (struct ip_fwd_tag *)(fwd_tag+1);
-               
+               struct ip_fwd_tag *ipfwd_tag = 
+                       (struct ip_fwd_tag *)(fwd_tag+1);
+
                next_hop = ipfwd_tag->next_hop;
                m_tag_delete(m, fwd_tag);
        }
-       
+
 #if INET6
        struct ip6_hdr *ip6 = NULL;
        int isipv6;
 #endif /* INET6 */
        int rstreason; /* For badport_bandlim accounting purposes */
        struct proc *proc0=current_proc();
-       
+
        KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_START,0,0,0,0,0);
 
 #if INET6
@@ -1154,7 +1564,10 @@ tcp_input(m, off0)
 
 #if INET6
        if (isipv6) {
-               /* Expect 32-bit aligned data pointer on strict-align platforms */
+               /* 
+                * Expect 32-bit aligned data pointer on 
+                * strict-align platforms 
+                */
                MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 
                /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */
@@ -1162,44 +1575,8 @@ tcp_input(m, off0)
                tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0;
                th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0);
 
-               if ((apple_hwcksum_rx != 0) && (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) {
-                       if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
-                               th->th_sum = m->m_pkthdr.csum_data;
-                       else {
-                               /* 
-                                * There is no established protocol for the case 
-                                * where IPv6 psuedoheader checksum is not computed
-                                * with our current drivers. Current drivers set
-                                * CSUM_PSEUDO_HDR. So if we do get here, we should
-                                * recalculate checksum.
-                                */
-                               if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
-                                       th->th_sum = 0;
-                               } else {
-                                       th->th_sum = 0xffff;
-                               }
-                       }
-
-                       th->th_sum ^= 0xffff;
-                       if (th->th_sum) {
-                               tcpstat.tcps_rcvbadsum++;
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->badformat, 1);
-                               
-                               goto dropnosock;
-                       }
-               }
-               else {
-                       if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
-                               tcpstat.tcps_rcvbadsum++;
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->badformat, 1);
-                                       
-                               goto dropnosock;
-                       }
-               }
+               if (tcp_input_checksum(AF_INET6, m, th, off0, tlen))
+                       goto dropnosock;
 
                KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport),
                     (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])),
@@ -1214,17 +1591,14 @@ tcp_input(m, off0)
                 */
                if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
                        /* XXX stat */
-                       
-                       if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                               atomic_add_64(&ifp->if_tcp_stat->unspecv6, 1);
-                       
+                       IF_TCP_STATINC(ifp, unspecv6);
                        goto dropnosock;
                }
-               DTRACE_TCP5(receive, sruct mbuf *, m, struct inpcb *, NULL,
+               DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL,
                        struct ip6_hdr *, ip6, struct tcpcb *, NULL, 
                        struct tcphdr *, th);
-        
-       ip_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
+
+               ip_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
        } else
 #endif /* INET6 */
        {
@@ -1235,9 +1609,6 @@ tcp_input(m, off0)
        if (off0 > sizeof (struct ip)) {
                ip_stripoptions(m, (struct mbuf *)0);
                off0 = sizeof(struct ip);
-               if (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16)
-                       m->m_pkthdr.csum_flags = 0; /* invalidate hwcksuming */
-
        }
        if (m->m_len < sizeof (struct tcpiphdr)) {
                if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) {
@@ -1250,63 +1621,12 @@ tcp_input(m, off0)
        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 
        ip = mtod(m, struct ip *);
-       ipov = (struct ipovly *)ip;
        th = (struct tcphdr *)(void *)((caddr_t)ip + off0);
        tlen = ip->ip_len;
 
-       if (m->m_pkthdr.aux_flags & MAUXF_SW_LRO_DID_CSUM) {
-               goto skip_checksum;
-       }
-       if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
-               if (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16) {
-                       u_short pseudo;
-                       char b[9];
-
-                       bcopy(ipov->ih_x1, b, sizeof (ipov->ih_x1));
-                       bzero(ipov->ih_x1, sizeof (ipov->ih_x1));
-                       ipov->ih_len = (u_short)tlen;
-#if BYTE_ORDER != BIG_ENDIAN
-                       HTONS(ipov->ih_len);
-#endif
-                       pseudo = in_cksum(m, sizeof (struct ip));
-                       bcopy(b, ipov->ih_x1, sizeof (ipov->ih_x1));
-
-                       th->th_sum = in_addword(pseudo, (m->m_pkthdr.csum_data & 0xFFFF));
-               } else {
-                       if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
-                               th->th_sum = m->m_pkthdr.csum_data;
-                       else
-                               th->th_sum = in_pseudo(ip->ip_src.s_addr,
-                                       ip->ip_dst.s_addr, htonl(m->m_pkthdr.csum_data +
-                                       ip->ip_len + IPPROTO_TCP));
-               }
-               th->th_sum ^= 0xffff;
-       } else {
-               char b[9];
-               /*
-                * Checksum extended TCP header and data.
-                */
-               bcopy(ipov->ih_x1, b, sizeof (ipov->ih_x1));
-               bzero(ipov->ih_x1, sizeof (ipov->ih_x1));
-               ipov->ih_len = (u_short)tlen;
-#if BYTE_ORDER != BIG_ENDIAN
-               HTONS(ipov->ih_len);
-#endif
-               len = sizeof (struct ip) + tlen;
-               th->th_sum = in_cksum(m, len);
-               bcopy(b, ipov->ih_x1, sizeof (ipov->ih_x1));
-
-               tcp_in_cksum_stats(len);
-       }
-       if (th->th_sum) {
-               tcpstat.tcps_rcvbadsum++;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->badformat, 1);
-               if (lrodebug) printf("tcp_input: bad xsum len = %d, tlen = %d, flags = %x, csum_flags = %x.\n",len, tlen, m->m_flags, m->m_pkthdr.csum_flags);                          
+       if (tcp_input_checksum(AF_INET, m, th, off0, tlen))
                goto dropnosock;
-       }
-skip_checksum:
+
 #if INET6
        /* Re-initialization for later version check */
        ip->ip_v = IPVERSION;
@@ -1315,7 +1635,7 @@ skip_checksum:
 
        DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL,
                struct ip *, ip, struct tcpcb *, NULL, struct tcphdr *, th);
-       
+
        KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport),
                (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)),
                  th->th_seq, th->th_ack, th->th_win);
@@ -1329,10 +1649,7 @@ skip_checksum:
        off = th->th_off << 2;
        if (off < sizeof (struct tcphdr) || off > tlen) {
                tcpstat.tcps_rcvbadoff++;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->badformat, 1);
-               
+               IF_TCP_STATINC(ifp, badformat);
                goto dropnosock;
        }
        tlen -= off;    /* tlen is used instead of ti->ti_len */
@@ -1351,7 +1668,6 @@ skip_checksum:
                                        return;
                                }
                                ip = mtod(m, struct ip *);
-                               ipov = (struct ipovly *)ip;
                                th = (struct tcphdr *)(void *)((caddr_t)ip + off0);
                        }
                }
@@ -1386,10 +1702,7 @@ skip_checksum:
         * This is a violation of the TCP specification.
         */
        if (drop_synfin && (thflags & (TH_SYN|TH_FIN)) == (TH_SYN|TH_FIN)) {
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->synfin, 1);
-                       
+               IF_TCP_STATINC(ifp, synfin);
                goto dropnosock;
        }
 #endif
@@ -1410,16 +1723,16 @@ skip_checksum:
        calculate_tcp_clock();
 
        /*
-        * Record the interface where this segment arrived on; this does not
-        * affect normal data output (for non-detached TCP) as it provides a
-        * hint about which route and interface to use for sending in the
-        * absence of a PCB, when scoped routing (and thus source interface
-        * selection) are enabled.
-        */
-       if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.rcvif != NULL)
-               ifscope = m->m_pkthdr.rcvif->if_index;
-       else
-               ifscope = IFSCOPE_NONE;
+        * Record the interface where this segment arrived on; this does not
+        * affect normal data output (for non-detached TCP) as it provides a
+        * hint about which route and interface to use for sending in the
+        * absence of a PCB, when scoped routing (and thus source interface
+        * selection) are enabled.
+        */
+       if ((m->m_pkthdr.pkt_flags & PKTF_LOOP) || m->m_pkthdr.rcvif == NULL)
+               ifscope = IFSCOPE_NONE;
+       else
+               ifscope = m->m_pkthdr.rcvif->if_index;
 
        /*
         * Convert TCP protocol specific fields to host format.
@@ -1490,42 +1803,24 @@ findpcb:
         */
        if (inp != NULL && (inp->inp_flags & INP_BOUND_IF))
                ifscope = inp->inp_boundifp->if_index;
-
-       /*
-        * If the PCB is present and the socket isn't allowed to use
-        * the cellular interface, indicate it as such for tcp_respond.
-        */
-       if (inp != NULL && (inp->inp_flags & INP_NO_IFT_CELLULAR))
-               nocell = 1;
-
-#if IPSEC
-       if (ipsec_bypass == 0)  {
+#if NECP
+       if (inp != NULL && (
 #if INET6
-               if (isipv6) {
-                       if (inp != NULL && ipsec6_in_reject_so(m, inp->inp_socket)) {
-                               IPSEC_STAT_INCREMENT(ipsec6stat.in_polvio);
-                               if (in_pcb_checkstate(inp, WNT_RELEASE, 0) == WNT_STOPUSING) 
-                                       inp = NULL;     // pretend we didn't find it 
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->badformatipsec, 1);    
-                                       
-                               goto dropnosock;
-                       }
-               } else
-#endif /* INET6 */
-                       if (inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) {
-                               IPSEC_STAT_INCREMENT(ipsecstat.in_polvio);
-                               if (in_pcb_checkstate(inp, WNT_RELEASE, 0) == WNT_STOPUSING) 
-                                       inp = NULL;     // pretend we didn't find it 
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->badformatipsec, 1);    
-                                       
-                               goto dropnosock;
-                       }
+               isipv6 ? !necp_socket_is_allowed_to_send_recv_v6(inp,
+                       th->th_dport, th->th_sport, &ip6->ip6_dst,
+                       &ip6->ip6_src, ifp, NULL) :
+#endif
+               !necp_socket_is_allowed_to_send_recv_v4(inp, th->th_dport,
+                       th->th_sport, &ip->ip_dst, &ip->ip_src,
+                       ifp, NULL))) {
+               if (in_pcb_checkstate(inp, WNT_RELEASE, 0)
+                   == WNT_STOPUSING) {
+                       inp = NULL;     /* pretend we didn't find it */
+               }
+               IF_TCP_STATINC(ifp, badformatipsec);
+               goto dropnosock;
        }
-#endif /*IPSEC*/
+#endif /* NECP */
 
        /*
         * If the state is CLOSED (i.e., TCB does not exist) then
@@ -1567,6 +1862,7 @@ findpcb:
                                        ntohs(th->th_sport), thflags);
                                break;
                        case 3:
+                       case 4:
                                if ((thflags & TH_SYN) && !(thflags & TH_ACK) &&
                                        !(m->m_flags & (M_BCAST | M_MCAST)) &&
 #if INET6
@@ -1601,10 +1897,7 @@ findpcb:
                                }
                }
                rstreason = BANDLIM_RST_CLOSEDPORT;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->noconnnolist, 1);
-
+               IF_TCP_STATINC(ifp, noconnnolist);
                goto dropwithresetnosock;
        }
        so = inp->inp_socket;
@@ -1631,10 +1924,7 @@ findpcb:
        tp = intotcpcb(inp);
        if (tp == 0) {
                rstreason = BANDLIM_RST_CLOSEDPORT;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->noconnlist, 1);
-
+               IF_TCP_STATINC(ifp, noconnlist);
                goto dropwithreset;
        }
        if (tp->t_state == TCPS_CLOSED)
@@ -1651,8 +1941,9 @@ findpcb:
                goto drop;
 #endif
 
-       /* Radar 7377561: Avoid processing packets while closing a listen socket */
-       if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN) == 0) 
+       /* Avoid processing packets while closing a listen socket */
+       if (tp->t_state == TCPS_LISTEN && 
+               (so->so_options & SO_ACCEPTCONN) == 0) 
                goto drop;
 
        if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) {
@@ -1678,15 +1969,19 @@ findpcb:
                        struct inpcb *oinp = sotoinpcb(so);
 #endif /* INET6 */
                        struct ifnet *head_ifscope;
-                       unsigned int head_nocell, head_recvanyif;
+                       unsigned int head_nocell, head_recvanyif,
+                                    head_noexpensive, head_awdl_unrestricted;
 
                        /* Get listener's bound-to-interface, if any */
                        head_ifscope = (inp->inp_flags & INP_BOUND_IF) ?
                            inp->inp_boundifp : NULL;
                        /* Get listener's no-cellular information, if any */
-                       head_nocell = (inp->inp_flags & INP_NO_IFT_CELLULAR) ? 1 : 0;
+                       head_nocell = INP_NO_CELLULAR(inp);
                        /* Get listener's recv-any-interface, if any */
                        head_recvanyif = (inp->inp_flags & INP_RECV_ANYIF);
+                       /* Get listener's no-expensive information, if any */
+                       head_noexpensive = INP_NO_EXPENSIVE(inp);
+                       head_awdl_unrestricted = INP_AWDL_UNRESTRICTED(inp);
 
                        /*
                         * If the state is LISTEN then ignore segment if it contains an RST.
@@ -1695,10 +1990,8 @@ findpcb:
                         * If it is from this socket, drop it, it must be forged.
                         */
                        if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) {
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->listbadsyn, 1);
-                       
+                               IF_TCP_STATINC(ifp, listbadsyn);
+
                                if (thflags & TH_RST) {
                                        goto drop;
                                }
@@ -1762,43 +2055,20 @@ findpcb:
                         * for the exchange.
                         *
                         * If we do not forbid deprecated addresses, we accept
-                        * the SYN packet.  RFC2462 does not suggest dropping
-                        * SYN in this case.
-                        * If we decipher RFC2462 5.5.4, it says like this:
-                        * 1. use of deprecated addr with existing
-                        *    communication is okay - "SHOULD continue to be
-                        *    used"
-                        * 2. use of it with new communication:
-                        *   (2a) "SHOULD NOT be used if alternate address
-                        *        with sufficient scope is available"
-                        *   (2b) nothing mentioned otherwise.
-                        * Here we fall into (2b) case as we have no choice in
-                        * our source address selection - we must obey the peer.
-                        *
-                        * The wording in RFC2462 is confusing, and there are
-                        * multiple description text for deprecated address
-                        * handling - worse, they are not exactly the same.
-                        * I believe 5.5.4 is the best one, so we follow 5.5.4.
+                        * the SYN packet.  RFC 4862 forbids dropping SYN in
+                        * this case.
                         */
                        if (isipv6 && !ip6_use_deprecated) {
-                               struct in6_ifaddr *ia6;
-
-                               ia6 = ip6_getdstifaddr(m);
-                               if (ia6 != NULL) {
-                                       IFA_LOCK_SPIN(&ia6->ia_ifa);
-                                       if (ia6->ia6_flags & IN6_IFF_DEPRECATED) {
-                                               IFA_UNLOCK(&ia6->ia_ifa);
-                                               IFA_REMREF(&ia6->ia_ifa);
+                               uint32_t ia6_flags;
+
+                               if (ip6_getdstifaddr_info(m, NULL,
+                                   &ia6_flags) == 0) {
+                                       if (ia6_flags & IN6_IFF_DEPRECATED) {
                                                tp = NULL;
                                                rstreason = BANDLIM_RST_OPENPORT;
-                                               
-                                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                                       atomic_add_64(&ifp->if_tcp_stat->deprecate6, 1);
-                                                       
+                                               IF_TCP_STATINC(ifp, deprecate6);
                                                goto dropwithreset;
                                        }
-                                       IFA_UNLOCK(&ia6->ia_ifa);
-                                       IFA_REMREF(&ia6->ia_ifa);
                                }
                        }
 #endif
@@ -1874,11 +2144,14 @@ findpcb:
                                inp->inp_flags &= ~INP_BOUND_IF;
                        }
                        /*
-                        * Inherit INP_NO_IFT_CELLULAR from listener.
+                        * Inherit restrictions from listener.
                         */
-                       if (head_nocell) {
-                               inp->inp_flags |= INP_NO_IFT_CELLULAR;
-                       }
+                       if (head_nocell)
+                               inp_set_nocellular(inp);
+                       if (head_noexpensive)
+                               inp_set_noexpensive(inp);
+                       if (head_awdl_unrestricted)
+                               inp_set_awdl_unrestricted(inp);
                        /*
                         * Inherit {IN,IN6}_RECV_ANYIF from listener.
                         */
@@ -1956,8 +2229,12 @@ findpcb:
                                struct tcpcb *, tp, int32_t, TCPS_LISTEN);
                        tp->t_state = TCPS_LISTEN;
                        tp->t_flags |= tp0->t_flags & (TF_NOPUSH|TF_NOOPT|TF_NODELAY);
-                       tp->t_flagsext |= (tp0->t_flagsext & TF_RXTFINDROP);
+                       tp->t_flagsext |= (tp0->t_flagsext & (TF_RXTFINDROP|TF_NOTIMEWAIT));
                        tp->t_keepinit = tp0->t_keepinit;
+                       tp->t_keepcnt = tp0->t_keepcnt;
+                       tp->t_keepintvl = tp0->t_keepintvl;
+                       tp->t_adaptive_wtimo = tp0->t_adaptive_wtimo;
+                       tp->t_adaptive_rtimo = tp0->t_adaptive_rtimo;
                        tp->t_inpcb->inp_ip_ttl = tp0->t_inpcb->inp_ip_ttl;
                        if ((so->so_flags & SOF_NOTSENT_LOWAT) != 0)
                                tp->t_notsent_lowat = tp0->t_notsent_lowat;
@@ -1970,72 +2247,12 @@ findpcb:
                        KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_END,0,0,0,0,0);
                }
        }
-       lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
+       lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
+               LCK_MTX_ASSERT_OWNED);
 
-       /*
-        * Radar 3529618
-        * This is the second part of the MSS DoS prevention code (after
-        * minmss on the sending side) and it deals with too many too small
-        * tcp packets in a too short timeframe (1 second).
-        *
-        * For every full second we count the number of received packets
-        * and bytes. If we get a lot of packets per second for this connection
-        * (tcp_minmssoverload) we take a closer look at it and compute the
-        * average packet size for the past second. If that is less than
-        * tcp_minmss we get too many packets with very small payload which
-        * is not good and burdens our system (and every packet generates
-        * a wakeup to the process connected to our socket). We can reasonable
-        * expect this to be small packet DoS attack to exhaust our CPU
-        * cycles.
-        *
-        * Care has to be taken for the minimum packet overload value. This
-        * value defines the minimum number of packets per second before we
-        * start to worry. This must not be too low to avoid killing for
-        * example interactive connections with many small packets like
-        * telnet or SSH.
-        *
-        * Setting either tcp_minmssoverload or tcp_minmss to "0" disables
-        * this check.
-        *
-        * Account for packet if payload packet, skip over ACK, etc.
-        */
        if (tp->t_state == TCPS_ESTABLISHED && tlen > 0) {
-               if (TSTMP_GT(tp->rcv_reset, tcp_now)) {
-                       tp->rcv_pps++;
-                       tp->rcv_byps += tlen + off;
-                       if (tp->rcv_byps > tp->rcv_maxbyps)
-                               tp->rcv_maxbyps = tp->rcv_byps;
-               /*
-                * Setting either tcp_minmssoverload or tcp_minmss to "0" disables
-                * the check. 
-                */
-                       if (tcp_minmss && tcp_minmssoverload && tp->rcv_pps > tcp_minmssoverload) {
-                               if ((tp->rcv_byps / tp->rcv_pps) < tcp_minmss) {
-                                       char    ipstrbuf[MAX_IPv6_STR_LEN];
-                                       printf("too many small tcp packets from "
-                                              "%s:%u, av. %ubyte/packet, "
-                                              "dropping connection\n",
-#if INET6
-                                               isipv6 ?
-                                               inet_ntop(AF_INET6, &inp->in6p_faddr, ipstrbuf,
-                                                                 sizeof(ipstrbuf)) :
-#endif
-                                               inet_ntop(AF_INET, &inp->inp_faddr, ipstrbuf,
-                                                                 sizeof(ipstrbuf)),
-                                               inp->inp_fport,
-                                               tp->rcv_byps / tp->rcv_pps);
-                                       tp = tcp_drop(tp, ECONNRESET);
-/*                                     tcpstat.tcps_minmssdrops++; */
-                                       goto drop;
-                               }
-                       }
-               } else {
-                       tp->rcv_reset = tcp_now + TCP_RETRANSHZ;
-                       tp->rcv_pps = 1;
-                       tp->rcv_byps = tlen + off;
-               }
-
-               /* Evaluate the rate of arrival of packets to see if the 
+               /* 
+                * Evaluate the rate of arrival of packets to see if the 
                 * receiver can reduce the ack traffic. The algorithm to 
                 * stretch acks will be enabled if the connection meets 
                 * certain criteria defined in tcp_stretch_ack_enable function.
@@ -2061,18 +2278,18 @@ findpcb:
        /* 
         * Keep track of how many bytes were received in the LRO packet
         */
-       if ((mauxf_sw_lro_pkt) && (nlropkts > 2))  {
+       if ((pktf_sw_lro_pkt) && (nlropkts > 2))  {
                tp->t_lropktlen += tlen;
        }
        /*
-          Explicit Congestion Notification - Flag that we need to send ECT if
-               + The IP Congestion experienced flag was set.
-               + Socket is in established state
-               + We negotiated ECN in the TCP setup
-               + This isn't a pure ack (tlen > 0)
-               + The data is in the valid window
-       
-               TE_SENDECE will be cleared when we receive a packet with TH_CWR set.
+        * Explicit Congestion Notification - Flag that we need to send ECT if
+        *      + The IP Congestion experienced flag was set.
+        *      + Socket is in established state
+        *      + We negotiated ECN in the TCP setup
+        *      + This isn't a pure ack (tlen > 0)
+        *      + The data is in the valid window
+        *
+        *      TE_SENDECE will be cleared when we receive a packet with TH_CWR set.
         */
        if (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED &&
                ((tp->ecn_flags & (TE_ECN_ON)) == (TE_ECN_ON)) && tlen > 0 &&
@@ -2082,19 +2299,22 @@ findpcb:
        }
        
        /*
-          Clear TE_SENDECE if TH_CWR is set. This is harmless, so we don't
-          bother doing extensive checks for state and whatnot.
+        * Clear TE_SENDECE if TH_CWR is set. This is harmless, so we don't
+        * bother doing extensive checks for state and whatnot.
         */
        if ((thflags & TH_CWR) == TH_CWR) {
                tp->ecn_flags &= ~TE_SENDECE;
        }
 
-       /* If we received an  explicit notification of congestion in 
+       /* 
+        * If we received an  explicit notification of congestion in 
         * ip tos ecn bits or by the CWR bit in TCP header flags, reset
-        * the ack-strteching state.
+        * the ack-strteching state. We need to handle ECN notification if
+        * an ECN setup SYN was sent even once.
         */
-       if (tp->t_state == TCPS_ESTABLISHED && (tp->t_flags & TF_STRETCHACK) != 0 &&
-               ((ip_ecn == IPTOS_ECN_CE) || ((thflags & TH_CWR) == TH_CWR)))
+       if (tp->t_state == TCPS_ESTABLISHED
+           && (tp->ecn_flags & TE_SETUPSENT)
+           && (ip_ecn == IPTOS_ECN_CE || (thflags & TH_CWR)))
                tcp_reset_stretch_ack(tp);
 
        /* 
@@ -2109,28 +2329,40 @@ findpcb:
                turnoff_lro = 1;
         }
 
+       /* Update rcvtime as a new segment was received on the connection */
+       tp->t_rcvtime = tcp_now;
+
        /*
         * Segment received on connection.
         * Reset idle time and keep-alive timer.
         */
-       tp->t_rcvtime = tcp_now;
        if (TCPS_HAVEESTABLISHED(tp->t_state))
-               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_KEEPIDLE(tp));
+               tcp_keepalive_reset(tp);
 
        /*
         * Process options if not in LISTEN state,
         * else do it below (after getting remote address).
         */
-       if (tp->t_state != TCPS_LISTEN && optp)
+       if (tp->t_state != TCPS_LISTEN && optp) {
                tcp_dooptions(tp, optp, optlen, th, &to, ifscope);
-
-       if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
-               if (to.to_flags & TOF_SCALE) {
-                       tp->t_flags |= TF_RCVD_SCALE;
-                       tp->requested_s_scale = to.to_requested_s_scale;
-                       tp->snd_wnd = th->th_win << tp->snd_scale;
-                       tiwin = tp->snd_wnd;
+#if MPTCP
+               mptcp_csum = mptcp_input_csum(tp, m, drop_hdrlen);
+               if (mptcp_csum) {
+                       tp->t_mpflags |= TMPF_SND_MPFAIL;
+                       tp->t_mpflags &= ~TMPF_EMBED_DSN;
+                       mptcp_notify_mpfail(so);
+                       m_freem(m);
+                       tcpstat.tcps_mp_badcsum++;
+                       tcp_check_timer_state(tp);
+                       tcp_unlock(so, 1, 0);
+                       KERNEL_DEBUG(DBG_FNC_TCP_INPUT |
+                           DBG_FUNC_END,0,0,0,0,0);
+                       return;     
                }
+               mptcp_insert_rmap(tp, m);
+#endif /* MPTCP */
+       }
+       if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
                if (to.to_flags & TOF_TS) {
                        tp->t_flags |= TF_RCVD_TSTMP;
                        tp->ts_recent = to.to_tsval;
@@ -2138,9 +2370,9 @@ findpcb:
                }
                if (to.to_flags & TOF_MSS)
                        tcp_mss(tp, to.to_mss, ifscope);
-               if (tp->sack_enable) {
+               if (SACK_ENABLED(tp)) {
                        if (!(to.to_flags & TOF_SACK))
-                               tp->sack_enable = 0;
+                               tp->t_flagsext &= ~(TF_SACK_ENABLE);
                        else
                                tp->t_flags |= TF_SACK_PERMIT;
                }
@@ -2168,7 +2400,7 @@ findpcb:
                        TCP_INC_VAR(tp->iaj_pktcnt, nlropkts);
                }
 
-               if (m->m_pkthdr.aux_flags & MAUXF_SW_LRO_PKT) {
+               if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) {
                        seg_size = m->m_pkthdr.lro_pktlen;
                }
                if ( tp->iaj_size == 0 || seg_size > tp->iaj_size ||
@@ -2183,7 +2415,11 @@ findpcb:
                                /* Compute inter-arrival jitter taking this packet 
                                 * as the second packet
                                 */
-                               compute_iaj(tp);
+                               if (pktf_sw_lro_pkt)
+                                       compute_iaj(tp, nlropkts,
+                                           m->m_pkthdr.lro_elapsed);
+                               else
+                                       compute_iaj(tp, 1, 0);
                        } 
                        if (seg_size  < tp->iaj_size) {
                                /* There is a smaller packet in the stream.
@@ -2193,7 +2429,7 @@ findpcb:
                                 * If there are too many packets smaller than iaj_size, 
                                 * we try to learn the iaj_size again.
                                 */
-                               tp->iaj_small_pkt++;
+                               TCP_INC_VAR(tp->iaj_small_pkt, nlropkts); 
                                if (tp->iaj_small_pkt > RESET_IAJ_SIZE_THRESH) {
                                        update_iaj_state(tp, seg_size, 1);
                                } else {
@@ -2256,51 +2492,21 @@ findpcb:
                            SEQ_LEQ(th->th_ack, tp->snd_max) &&
                            tp->snd_cwnd >= tp->snd_ssthresh &&
                            (!IN_FASTRECOVERY(tp) && 
-                           ((!tp->sack_enable && tp->t_dupacks < tcprexmtthresh) ||
-                            (tp->sack_enable && to.to_nsacks == 0 &&
-                             TAILQ_EMPTY(&tp->snd_holes))))) {
+                           ((!(SACK_ENABLED(tp)) && 
+                           tp->t_dupacks < tp->t_rexmtthresh) ||
+                           (SACK_ENABLED(tp) && to.to_nsacks == 0 &&
+                           TAILQ_EMPTY(&tp->snd_holes))))) {
                                /*
                                 * this is a pure ack for outstanding data.
                                 */
                                ++tcpstat.tcps_predack;
-                               /*
-                                * "bad retransmit" recovery
-                                */
-                               if (tp->t_rxtshift == 1 &&
-                                   TSTMP_LT(tcp_now, tp->t_badrxtwin)) {
-                                       ++tcpstat.tcps_sndrexmitbad;
-                                       tp->snd_cwnd = tp->snd_cwnd_prev;
-                                       tp->snd_ssthresh =
-                                           tp->snd_ssthresh_prev;
-                                       tp->snd_recover = tp->snd_recover_prev;
-                                       if (tp->t_flags & TF_WASFRECOVERY)
-                                           ENTER_FASTRECOVERY(tp);
-                                       tp->snd_nxt = tp->snd_max;
-                                       tp->t_badrxtwin = 0;
-                                       tp->t_rxtshift = 0;
-                                       tp->rxt_start = 0;
-                                       tcp_bad_rexmt_fix_sndbuf(tp);
-                                       DTRACE_TCP5(cc, void, NULL, struct inpcb *, tp->t_inpcb,
-                                               struct tcpcb *, tp, struct tcphdr *, th,
-                                               int32_t, TCP_CC_BAD_REXMT_RECOVERY);
-                               }
-                               /*
-                                * Recalculate the transmit timer / rtt.
-                                *
-                                * Some boxes send broken timestamp replies
-                                * during the SYN+ACK phase, ignore
-                                * timestamps of 0 or we could calculate a
-                                * huge RTT and blow up the retransmit timer.
-                                */
-                               if (((to.to_flags & TOF_TS) != 0) && (to.to_tsecr != 0) &&
-                                       TSTMP_GEQ(tcp_now, to.to_tsecr)) { 
-                                       tcp_xmit_timer(tp,
-                                               tcp_now - to.to_tsecr);
-                               } else if (tp->t_rtttime &&
-                                       SEQ_GT(th->th_ack, tp->t_rtseq)) {
-                                       tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
-                               }
-                               acked = th->th_ack - tp->snd_una;
+
+                               tcp_bad_rexmt_check(tp, th, &to),
+
+                               /* Recalculate the RTT */
+                               tcp_compute_rtt(tp, &to, th);
+
+                               acked = BYTES_ACKED(th, tp);
                                tcpstat.tcps_rcvackpack++;
                                tcpstat.tcps_rcvackbyte += acked;
                                
@@ -2308,14 +2514,14 @@ findpcb:
                                 * avoidance phase. The calculations in this function 
                                 * assume that snd_una is not updated yet. 
                                 */
-                               if (CC_ALGO(tp)->inseq_ack_rcvd != NULL)
-                                       CC_ALGO(tp)->inseq_ack_rcvd(tp, th);
-
-                               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, struct tcphdr *, th,
-                                       int32_t, TCP_CC_INSEQ_ACK_RCVD);
-
+                               if (CC_ALGO(tp)->congestion_avd != NULL)
+                                       CC_ALGO(tp)->congestion_avd(tp, th);
+                               tcp_ccdbg_trace(tp, th, TCP_CC_INSEQ_ACK_RCVD);
                                sbdrop(&so->so_snd, acked);
+                               if (so->so_flags & SOF_ENABLE_MSGS) {
+                                       VERIFY(acked <= so->so_msg_state->msg_serial_bytes);
+                                       so->so_msg_state->msg_serial_bytes -= acked;
+                               }
                                tcp_sbsnd_trim(&so->so_snd);
 
                                if (SEQ_GT(tp->snd_una, tp->snd_recover) &&
@@ -2328,9 +2534,13 @@ findpcb:
                                 * to th_ack.
                                 */
                                tp->snd_wl2 = th->th_ack;
-                               tp->t_dupacks = 0;
+
+                               if (tp->t_dupacks > 0) {
+                                       tp->t_dupacks = 0;
+                                       tp->t_rexmtthresh = tcprexmtthresh;
+                               }
+
                                m_freem(m);
-                               ND6_HINT(tp); /* some progress has been done */
 
                                /*
                                 * If all outstanding data are acked, stop
@@ -2341,10 +2551,14 @@ findpcb:
                                 * are ready to send, let tcp_output
                                 * decide between more output or persist.
                                 */
-                               if (tp->snd_una == tp->snd_max)
+                               if (tp->snd_una == tp->snd_max) {
                                        tp->t_timer[TCPT_REXMT] = 0;
-                               else if (tp->t_timer[TCPT_PERSIST] == 0)
-                                       tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur);
+                                       tp->t_timer[TCPT_PTO] = 0;
+                               } else if (tp->t_timer[TCPT_PERSIST] == 0) {
+                                       tp->t_timer[TCPT_REXMT] =
+                                           OFFSET_FROM_START(tp,
+                                           tp->t_rxtcur);
+                               }
 
                                if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 &&
                                        tp->t_bwmeas != NULL)
@@ -2374,17 +2588,17 @@ findpcb:
                         */
                        if (turnoff_lro) {
                                tcp_lro_remove_state(tp->t_inpcb->inp_laddr,
-                                tp->t_inpcb->inp_faddr,
-                                tp->t_inpcb->inp_lport, 
-                                tp->t_inpcb->inp_fport);
+                                       tp->t_inpcb->inp_faddr,
+                                       tp->t_inpcb->inp_lport, 
+                                       tp->t_inpcb->inp_fport);
                                tp->t_flagsext &= ~TF_LRO_OFFLOADED;
                                tp->t_idleat = tp->rcv_nxt;
-                       } else if (sw_lro && !mauxf_sw_lro_pkt && !isipv6 &&
-                           (so->so_flags & SOF_USELRO) &&      
-                           (m->m_pkthdr.rcvif->if_type != IFT_CELLULAR) &&
+                       } else if (sw_lro && !pktf_sw_lro_pkt && !isipv6 &&
+                           (so->so_flags & SOF_USELRO) &&      
+                           !IFNET_IS_CELLULAR(m->m_pkthdr.rcvif) &&
                            (m->m_pkthdr.rcvif->if_type != IFT_LOOP) &&
                            ((th->th_seq - tp->irs) > 
-                               (tp->t_maxseg << lro_start)) &&
+                           (tp->t_maxseg << lro_start)) &&
                            ((tp->t_idleat == 0) || ((th->th_seq - 
                             tp->t_idleat) > (tp->t_maxseg << lro_start)))) {
                                tp->t_flagsext |= TF_LRO_OFFLOADED;
@@ -2393,7 +2607,7 @@ findpcb:
                        }
 
                        /* Clean receiver SACK report if present */
-                       if (tp->sack_enable && tp->rcv_numsacks)
+                       if (SACK_ENABLED(tp) && tp->rcv_numsacks)
                                tcp_clean_sackreport(tp);
                        ++tcpstat.tcps_preddat;
                        tp->rcv_nxt += tlen;
@@ -2410,15 +2624,25 @@ findpcb:
                        TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts);
                        tcpstat.tcps_rcvbyte += tlen;
                        if (nstat_collect) {
-                               if (m->m_pkthdr.aux_flags & MAUXF_SW_LRO_PKT) {
-                                       locked_add_64(&inp->inp_stat->rxpackets, m->m_pkthdr.lro_npkts);
-                               }
-                               else {
-                                       locked_add_64(&inp->inp_stat->rxpackets, 1);
+                               if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) {
+                                       INP_ADD_STAT(inp, cell, wifi, wired, 
+                                           rxpackets, m->m_pkthdr.lro_npkts);
+                               } else {
+                                       INP_ADD_STAT(inp, cell, wifi, wired,
+                                           rxpackets, 1);
                                }
-                               locked_add_64(&inp->inp_stat->rxbytes, tlen);
+                               INP_ADD_STAT(inp, cell, wifi, wired,rxbytes,
+                                   tlen);
                        }
-                       ND6_HINT(tp);   /* some progress has been done */
+
+                       /*
+                        * Calculate the RTT on the receiver only if the 
+                        * connection is in streaming mode and the last 
+                        * packet was not an end-of-write
+                        */
+                       if ((tp->t_flags & TF_STRETCHACK) &&
+                               !(tp->t_flagsext & TF_STREAMEOW))
+                               tcp_compute_rtt(tp, &to, th);
 
                        tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen);
                        
@@ -2427,8 +2651,16 @@ findpcb:
                         */
                        so_recv_data_stat(so, m, 0);
                        m_adj(m, drop_hdrlen);  /* delayed header drop */
-                       if (sbappendstream(&so->so_rcv, m))
+                       
+                       /*
+                        * If message delivery (SOF_ENABLE_MSGS) is enabled on  
+                        * this socket, deliver the packet received as an
+                        * in-order message with sequence number attached to it.
+                        */
+                       if (sbappendstream_rcvdemux(so, m, 
+                           th->th_seq - (tp->irs + 1), 0)) {
                                sorwakeup(so);
+                       }           
 #if INET6
                        if (isipv6) {
                                KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport),
@@ -2452,6 +2684,9 @@ findpcb:
                                tp->t_flags |= TF_ACKNOW;
                                tcp_output(tp);
                        }
+
+                       tcp_adaptive_rwtimo_check(tp, tlen);
+
                        tcp_check_timer_state(tp);
                        tcp_unlock(so, 1, 0);
                        KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0);
@@ -2465,12 +2700,9 @@ findpcb:
         * Receive window is amount of space in rcv queue,
         * but not less than advertised window.
         */
-       lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-
-       { int win;
-
+       lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
+           LCK_MTX_ASSERT_OWNED);
        win = tcp_sbspace(tp);
-
        if (win < 0)
                win = 0;
        else {  /* clip rcv window to 4K for modems */
@@ -2478,7 +2710,21 @@ findpcb:
                        win = min(win, slowlink_wsize);
        }
        tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt));
+#if MPTCP
+       /*
+        * Ensure that the subflow receive window isn't greater
+        * than the connection level receive window.
+        */
+       if ((tp->t_mpflags & TMPF_MPTCP_TRUE) &&
+           (mp_tp = tptomptp(tp))) {
+               MPT_LOCK(mp_tp);
+               if (tp->rcv_wnd > mp_tp->mpt_rcvwnd) {
+                       tp->rcv_wnd = mp_tp->mpt_rcvwnd;
+                       tcpstat.tcps_mp_reducedwin++;
+               }
+               MPT_UNLOCK(mp_tp);
        }
+#endif /* MPTCP */
 
        switch (tp->t_state) {
 
@@ -2497,7 +2743,8 @@ findpcb:
                register struct sockaddr_in6 *sin6;
 #endif
 
-               lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
+               lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx,
+                   LCK_MTX_ASSERT_OWNED);
 #if INET6
                if (isipv6) {
                        MALLOC(sin6, struct sockaddr_in6 *, sizeof *sin6,
@@ -2535,7 +2782,8 @@ findpcb:
                        laddr = inp->inp_laddr;
                        if (inp->inp_laddr.s_addr == INADDR_ANY)
                                inp->inp_laddr = ip->ip_dst;
-                       if (in_pcbconnect(inp, (struct sockaddr *)sin, proc0, NULL)) {
+                       if (in_pcbconnect(inp, (struct sockaddr *)sin, proc0,
+                           IFSCOPE_NONE, NULL)) {
                                inp->inp_laddr = laddr;
                                FREE(sin, M_SONAME);
                                goto drop;
@@ -2545,9 +2793,9 @@ findpcb:
 
                tcp_dooptions(tp, optp, optlen, th, &to, ifscope);
 
-               if (tp->sack_enable) {
+               if (SACK_ENABLED(tp)) {
                        if (!(to.to_flags & TOF_SACK))
-                               tp->sack_enable = 0;
+                               tp->t_flagsext &= ~(TF_SACK_ENABLE);
                        else
                                tp->t_flags |= TF_SACK_PERMIT;
                }
@@ -2573,11 +2821,20 @@ findpcb:
                        struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED);
                tp->t_state = TCPS_SYN_RECEIVED;
                tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, 
-                       tp->t_keepinit ? tp->t_keepinit : tcp_keepinit);
+                       TCP_CONN_KEEPINIT(tp));
                dropsocket = 0;         /* committed to socket */
 
                if (inp->inp_flowhash == 0)
                        inp->inp_flowhash = inp_calc_flowhash(inp);
+#if INET6
+               /* update flowinfo - RFC 6437 */
+               if (inp->inp_flow == 0 &&
+                   inp->in6p_flags & IN6P_AUTOFLOWLABEL) {
+                       inp->inp_flow &= ~IPV6_FLOWLABEL_MASK;
+                       inp->inp_flow |=
+                           (htonl(inp->inp_flowhash) & IPV6_FLOWLABEL_MASK);
+               }
+#endif /* INET6 */
 
                /* reset the incomp processing flag */
                so->so_flags &= ~(SOF_INCOMP_INPROGRESS);
@@ -2606,12 +2863,19 @@ findpcb:
                    (SEQ_LEQ(th->th_ack, tp->snd_una) ||
                     SEQ_GT(th->th_ack, tp->snd_max))) {
                                rstreason = BANDLIM_RST_OPENPORT;
-                               
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->ooopacket, 1);
-                                       
+                               IF_TCP_STATINC(ifp, ooopacket);
                                goto dropwithreset;
                }
+
+               /*
+                * In SYN_RECEIVED state, if we recv some SYNS with
+                * window scale and others without, window scaling should
+                * be disabled. Otherwise the window advertised will be
+                * lower if we assume scaling and the other end does not.
+                */
+               if ((thflags & TH_SYN) &&
+                   !(to.to_flags & TOF_SCALE))
+                       tp->t_flags &= ~TF_RCVD_SCALE;
                break;
 
        /*
@@ -2631,14 +2895,19 @@ findpcb:
                    (SEQ_LEQ(th->th_ack, tp->iss) ||
                     SEQ_GT(th->th_ack, tp->snd_max))) {
                        rstreason = BANDLIM_UNLIMITED;
-                       
-                       if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                               atomic_add_64(&ifp->if_tcp_stat->ooopacket, 1);
-                               
+                       IF_TCP_STATINC(ifp, ooopacket);
                        goto dropwithreset;
                }
                if (thflags & TH_RST) {
                        if ((thflags & TH_ACK) != 0) {
+#if MPTCP
+                               if ((so->so_flags & SOF_MPTCP_FASTJOIN) &&
+                                       SEQ_GT(th->th_ack, tp->iss+1)) {
+                                       so->so_flags &= ~SOF_MPTCP_FASTJOIN;
+                                       /* ignore the RST and retransmit SYN */
+                                       goto drop;
+                               }
+#endif /* MPTCP */
                                soevent(so, 
                                    (SO_FILT_HINT_LOCKED |
                                    SO_FILT_HINT_CONNRESET));
@@ -2659,6 +2928,7 @@ findpcb:
                        if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE)) {
                                /* ECN-setup SYN-ACK */
                                tp->ecn_flags |= TE_SETUPRECEIVED;
+                               tcpstat.tcps_ecn_setup++;
                        }
                        else {
                                /* non-ECN-setup SYN-ACK */
@@ -2710,11 +2980,27 @@ findpcb:
                                DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
                                        struct tcpcb *, tp, int32_t, TCPS_ESTABLISHED);
                                tp->t_state = TCPS_ESTABLISHED;
-                               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_KEEPIDLE(tp));
+                               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,
+                                       TCP_CONN_KEEPIDLE(tp));
                                if (nstat_collect)
                                        nstat_route_connect_success(tp->t_inpcb->inp_route.ro_rt);
                        }
-                       isconnected = TRUE;
+#if MPTCP
+                       /*
+                        * Do not send the connect notification for additional
+                        * subflows until ACK for 3-way handshake arrives.
+                        */
+                       if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) &&
+                           (tp->t_mpflags & TMPF_SENT_JOIN)) {
+                               isconnected = FALSE;
+                               /* Start data xmit if fastjoin */
+                               if (mptcp_fastjoin && (so->so_flags & SOF_MPTCP_FASTJOIN)) {
+                                       soevent(so, (SO_FILT_HINT_LOCKED | 
+                                           SO_FILT_HINT_MPFASTJ));
+                               }
+                       } else
+#endif /* MPTCP */
+                               isconnected = TRUE;
                } else {
                        /*
                         *  Received initial SYN in SYN-SENT[*] state => simul-
@@ -2853,12 +3139,12 @@ trimthenstep6:
                if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
                    SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) ||
                    (tp->rcv_wnd == 0 && 
-                       ((tp->last_ack_sent == th->th_seq) || ((tp->last_ack_sent -1) == th->th_seq)))) {
+                   ((tp->last_ack_sent == th->th_seq) || 
+                   ((tp->last_ack_sent -1) == th->th_seq)))) {
                        switch (tp->t_state) {
 
                        case TCPS_SYN_RECEIVED:
-                               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                                       atomic_add_64(&ifp->if_tcp_stat->rstinsynrcv, 1);
+                               IF_TCP_STATINC(ifp, rstinsynrcv);
                                so->so_error = ECONNREFUSED;
                                goto close;
 
@@ -2876,14 +3162,10 @@ trimthenstep6:
                                so->so_error = ECONNRESET;
                        close:
                                postevent(so, 0, EV_RESET);
-                               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, int32_t, TCPS_CLOSED);
-
                                soevent(so,
                                    (SO_FILT_HINT_LOCKED |
                                    SO_FILT_HINT_CONNRESET));
 
-                               tp->t_state = TCPS_CLOSED;
                                tcpstat.tcps_drops++;
                                tp = tcp_close(tp);
                                break;
@@ -2926,9 +3208,12 @@ trimthenstep6:
                        tcpstat.tcps_rcvdupbyte += tlen;
                        tcpstat.tcps_pawsdrop++;
                        if (nstat_collect) {
-                               nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, tlen, NSTAT_RX_FLAG_DUPLICATE);
-                               locked_add_64(&inp->inp_stat->rxpackets, 1);
-                               locked_add_64(&inp->inp_stat->rxbytes, tlen);
+                               nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 
+                                       1, tlen, NSTAT_RX_FLAG_DUPLICATE);
+                               INP_ADD_STAT(inp, cell, wifi, wired,
+                                   rxpackets, 1);
+                               INP_ADD_STAT(inp, cell, wifi, wired,
+                                   rxbytes, tlen);
                                tp->t_stat.rxduplicatebytes += tlen;
                        }
                        if (tlen)
@@ -2946,10 +3231,7 @@ trimthenstep6:
         */
        if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
                rstreason = BANDLIM_RST_OPENPORT;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->dospacket, 1);
-                       
+               IF_TCP_STATINC(ifp, dospacket);
                goto dropwithreset;
        }
 
@@ -2994,9 +3276,10 @@ trimthenstep6:
                        tcpstat.tcps_rcvpartdupbyte += todrop;
                }
                if (nstat_collect) {
-                       nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, todrop, NSTAT_RX_FLAG_DUPLICATE);
-                       locked_add_64(&inp->inp_stat->rxpackets, 1);
-                       locked_add_64(&inp->inp_stat->rxbytes, todrop);
+                       nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, 
+                               todrop, NSTAT_RX_FLAG_DUPLICATE);
+                       INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1);
+                       INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, todrop);
                        tp->t_stat.rxduplicatebytes += todrop;
                }
                drop_hdrlen += todrop;  /* drop from the top afterwards */
@@ -3011,18 +3294,19 @@ trimthenstep6:
        }
 
        /*
-        * If new data are received on a connection after the
-        * user processes are gone, then RST the other end.
+        * If new data are received on a connection after the user processes
+        * are gone, then RST the other end.  Note that an MPTCP subflow socket
+        * would have SS_NOFDREF set by default, so check to make sure that
+        * we test for SOF_MP_SUBFLOW socket flag (which would be cleared when
+        * the socket is closed.)
         */
-       if ((so->so_state & SS_NOFDREF) &&
+       if (!(so->so_flags & SOF_MP_SUBFLOW) && 
+           (so->so_state & SS_NOFDREF) &&
            tp->t_state > TCPS_CLOSE_WAIT && tlen) {
                tp = tcp_close(tp);
                tcpstat.tcps_rcvafterclose++;
                rstreason = BANDLIM_UNLIMITED;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->cleanup, 1);
-                       
+               IF_TCP_STATINC(ifp, cleanup);
                goto dropwithreset;
        }
 
@@ -3102,10 +3386,7 @@ trimthenstep6:
                tp = tcp_drop(tp, ECONNRESET);
                rstreason = BANDLIM_UNLIMITED;
                postevent(so, 0, EV_RESET);
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->synwindow, 1);
-                       
+               IF_TCP_STATINC(ifp, synwindow);
                goto dropwithreset;
        }
 
@@ -3127,6 +3408,7 @@ trimthenstep6:
        /*
         * Ack processing.
         */
+
        switch (tp->t_state) {
 
        /*
@@ -3162,7 +3444,8 @@ trimthenstep6:
                        DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
                                struct tcpcb *, tp, int32_t, TCPS_ESTABLISHED);
                        tp->t_state = TCPS_ESTABLISHED;
-                       tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_KEEPIDLE(tp));
+                       tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp,
+                               TCP_CONN_KEEPIDLE(tp));
                        if (nstat_collect)
                                nstat_route_connect_success(tp->t_inpcb->inp_route.ro_rt);
                }
@@ -3172,12 +3455,21 @@ trimthenstep6:
                 */
                if (tlen == 0 && (thflags & TH_FIN) == 0)
                        (void) tcp_reass(tp, (struct tcphdr *)0, &tlen,
-                           (struct mbuf *)0);
+                           NULL, ifp);
                tp->snd_wl1 = th->th_seq - 1;
 
                /* FALLTHROUGH */
-
-               isconnected = TRUE;
+#if MPTCP
+               /*
+                * Do not send the connect notification for additional subflows
+                * until ACK for 3-way handshake arrives.
+                */
+               if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) &&
+                   (tp->t_mpflags & TMPF_SENT_JOIN)) {
+                       isconnected = FALSE;
+               } else
+#endif /* MPTCP */
+                       isconnected = TRUE;
 
        /*
         * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
@@ -3198,19 +3490,109 @@ trimthenstep6:
                        tcpstat.tcps_rcvacktoomuch++;
                        goto dropafterack;
                }
-               if (tp->sack_enable &&
+               if (SACK_ENABLED(tp) &&
                    (to.to_nsacks > 0 || !TAILQ_EMPTY(&tp->snd_holes)))
-                       tcp_sack_doack(tp, &to, th->th_ack);
+                       tcp_sack_doack(tp, &to, th, &sack_bytes_acked);
+
+#if MPTCP
+               if ((tp->t_mpuna) && (SEQ_GEQ(th->th_ack, tp->t_mpuna))) {
+                       if (tp->t_mpflags & TMPF_PREESTABLISHED) {
+                               /* MP TCP establishment succeeded */
+                               tp->t_mpuna = 0;
+                               if (tp->t_mpflags & TMPF_JOINED_FLOW) {
+                                       if (tp->t_mpflags & TMPF_SENT_JOIN) {
+                                               tp->t_mpflags &=
+                                                   ~TMPF_PREESTABLISHED;
+                                               tp->t_mpflags |=
+                                                   TMPF_MPTCP_TRUE;
+                                               so->so_flags |= SOF_MPTCP_TRUE;
+                                               if (mptcp_dbg >= MP_ERR_DEBUG)
+                                                       printf("MPTCP SUCCESS"
+                                                           " %s \n",__func__);
+                                               tp->t_timer[TCPT_JACK_RXMT] = 0;
+                                               tp->t_mprxtshift = 0;
+                                               isconnected = TRUE;
+                                       } else {
+                                               isconnected = FALSE;
+                                       }
+                               } else {
+                                       isconnected = TRUE;
+                                       tp->t_mpflags &= ~TMPF_SENT_KEYS;
+                               }
+                       }
+               }
+#endif /* MPTCP */
+               /*
+                * If we have outstanding data (other than
+                * a window probe), this is a completely
+                * duplicate ack (ie, window info didn't
+                * change) and the ack is the biggest we've seen.
+                */ 
                if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
                        if (tlen == 0 && tiwin == tp->snd_wnd) {
+                               /*
+                                * If both ends send FIN at the same time,
+                                * then the ack will be a duplicate ack
+                                * but we have to process the FIN. Check
+                                * for this condition and process the FIN
+                                * instead of the dupack
+                                */ 
+                               if ((thflags & TH_FIN) &&
+                                       (tp->t_flags & TF_SENTFIN) &&
+                                       !TCPS_HAVERCVDFIN(tp->t_state) &&
+                                       (th->th_ack + 1) == tp->snd_max) {
+                                       break;
+                               }
+process_dupack:
+#if MPTCP
+                               /*
+                                * MPTCP options that are ignored must
+                                * not be treated as duplicate ACKs.
+                                */
+                               if (to.to_flags & TOF_MPTCP) {
+                                       goto drop;
+                               }
+
+                               if ((isconnected) && (tp->t_mpflags & TMPF_JOINED_FLOW)) {
+                                       if (mptcp_dbg >= MP_ERR_DEBUG)
+                                               printf("%s:  bypass ack recovery\n",__func__);
+                                       break;
+                               }
+#endif /* MPTCP */
+                               /*
+                                * If a duplicate acknowledgement was seen
+                                * after ECN, it indicates packet loss in
+                                * addition to ECN. Reset INRECOVERY flag
+                                * so that we can process partial acks
+                                * correctly
+                                */
+                               if (tp->ecn_flags & TE_INRECOVERY)
+                                       tp->ecn_flags &= ~TE_INRECOVERY;
+
                                tcpstat.tcps_rcvdupack++;
+                               ++tp->t_dupacks;
+
+                               /*
+                                * Check if we need to reset the limit on
+                                * early retransmit
+                                */
+                               if (tp->t_early_rexmt_count > 0 &&
+                                   TSTMP_GEQ(tcp_now,
+                                   (tp->t_early_rexmt_win +
+                                   TCP_EARLY_REXMT_WIN)))
+                                       tp->t_early_rexmt_count = 0;
+
+                               /* 
+                                * Is early retransmit needed? We check for
+                                * this when the connection is waiting for
+                                * duplicate acks to enter fast recovery.
+                                */
+                               if (!IN_FASTRECOVERY(tp))
+                                       tcp_early_rexmt_check(tp, th);
+
                                /*
-                                * If we have outstanding data (other than
-                                * a window probe), this is a completely
-                                * duplicate ack (ie, window info didn't
-                                * change), the ack is the biggest we've
-                                * seen and we've seen exactly our rexmt
-                                * threshhold of them, assume a packet
+                                * If we've seen exactly rexmt threshold 
+                                * of duplicate acks, assume a packet
                                 * has been dropped and retransmit it.
                                 * Kludge snd_nxt & the congestion
                                 * window so we send only this one
@@ -3229,11 +3611,32 @@ trimthenstep6:
                                 * network.
                                 */
                                if (tp->t_timer[TCPT_REXMT] == 0 ||
-                                   th->th_ack != tp->snd_una)
+                                   (th->th_ack != tp->snd_una
+                                   && sack_bytes_acked == 0)) {
                                        tp->t_dupacks = 0;
-                               else if (++tp->t_dupacks > tcprexmtthresh ||
-                                         IN_FASTRECOVERY(tp)) {
-                                       if (tp->sack_enable && IN_FASTRECOVERY(tp)) {
+                                       tp->t_rexmtthresh = tcprexmtthresh;
+                               } else if (tp->t_dupacks > tp->t_rexmtthresh ||
+                                       IN_FASTRECOVERY(tp)) {
+
+                                       /*
+                                        * If this connection was seeing packet
+                                        * reordering, then recovery might be
+                                        * delayed to disambiguate between
+                                        * reordering and loss
+                                        */
+                                       if (SACK_ENABLED(tp) && !IN_FASTRECOVERY(tp) &&
+                                           (tp->t_flagsext & 
+                                           (TF_PKTS_REORDERED|TF_DELAY_RECOVERY)) ==
+                                           (TF_PKTS_REORDERED|TF_DELAY_RECOVERY)) {
+                                               /*
+                                                * Since the SACK information is already
+                                                * updated, this ACK will be dropped
+                                                */
+                                               break;
+                                       }
+
+                                       if (SACK_ENABLED(tp) 
+                                           && IN_FASTRECOVERY(tp)) {
                                                int awnd;
                                                
                                                /*
@@ -3252,13 +3655,11 @@ trimthenstep6:
                                        } else
                                                tp->snd_cwnd += tp->t_maxseg;
 
-                                       DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                               struct tcpcb *, tp, struct tcphdr *, th,
-                                               int32_t, TCP_CC_IN_FASTRECOVERY);
+                                       tcp_ccdbg_trace(tp, th, TCP_CC_IN_FASTRECOVERY);
 
                                        (void) tcp_output(tp);
                                        goto drop;
-                               } else if (tp->t_dupacks == tcprexmtthresh) {
+                               } else if (tp->t_dupacks == tp->t_rexmtthresh) {
                                        tcp_seq onxt = tp->snd_nxt;
 
                                        /*
@@ -3268,10 +3669,12 @@ trimthenstep6:
                                         * check to see if we're in newreno
                                         * recovery.
                                         */
-                                       if (tp->sack_enable) {
+                                       if (SACK_ENABLED(tp)) {
                                                if (IN_FASTRECOVERY(tp)) {
                                                        tp->t_dupacks = 0;
                                                        break;
+                                               } else if (tp->t_flagsext & TF_DELAY_RECOVERY) {
+                                                       break;
                                                }
                                        } else {
                                                if (SEQ_LEQ(th->th_ack,
@@ -3281,6 +3684,33 @@ trimthenstep6:
                                                }
                                        }
                                        
+                                       tp->snd_recover = tp->snd_max;
+                                       tp->t_timer[TCPT_PTO] = 0;
+                                       tp->t_rtttime = 0;
+
+                                       /*
+                                        * If the connection has seen pkt
+                                        * reordering, delay recovery until
+                                        * it is clear that the packet
+                                        * was lost.
+                                        */
+                                       if (SACK_ENABLED(tp) &&
+                                           (tp->t_flagsext &
+                                           (TF_PKTS_REORDERED|TF_DELAY_RECOVERY))
+                                           == TF_PKTS_REORDERED &&
+                                           !IN_FASTRECOVERY(tp) &&
+                                           tp->t_reorderwin > 0 &&
+                                           tp->t_state == TCPS_ESTABLISHED) {
+                                               tp->t_timer[TCPT_DELAYFR] =
+                                                   OFFSET_FROM_START(tp,
+                                                   tp->t_reorderwin);
+                                               tp->t_flagsext |= TF_DELAY_RECOVERY;
+                                               tcpstat.tcps_delay_recovery++;
+                                               tcp_ccdbg_trace(tp, th,
+                                                   TCP_CC_DELAY_FASTRECOVERY);
+                                               break;
+                                       }
+
                                        /*
                                         * If the current tcp cc module has 
                                         * defined a hook for tasks to run
@@ -3289,20 +3719,27 @@ trimthenstep6:
                                        if (CC_ALGO(tp)->pre_fr != NULL)
                                                CC_ALGO(tp)->pre_fr(tp);
                                        ENTER_FASTRECOVERY(tp);
-                                       tp->snd_recover = tp->snd_max;
                                        tp->t_timer[TCPT_REXMT] = 0;
-                                       tp->t_rtttime = 0;
-                                       if ((tp->ecn_flags & TE_ECN_ON) == TE_ECN_ON) {
+                                       if ((tp->ecn_flags & TE_ECN_ON)
+                                           == TE_ECN_ON) 
                                                tp->ecn_flags |= TE_SENDCWR;
-                                       }
-                                       if (tp->sack_enable) {
+
+                                       if (SACK_ENABLED(tp)) {
                                                tcpstat.tcps_sack_recovery_episode++;
                                                tp->sack_newdata = tp->snd_nxt;
                                                tp->snd_cwnd = tp->t_maxseg;
 
-                                               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                                       struct tcpcb *, tp, struct tcphdr *, th,
-                                                       int32_t, TCP_CC_ENTER_FASTRECOVERY);
+                                               /*
+                                                * Enable probe timeout to detect 
+                                                * a tail loss in the recovery
+                                                * window.
+                                                */
+                                               tp->t_timer[TCPT_PTO] =
+                                                   OFFSET_FROM_START(tp,
+                                                   max(10, (tp->t_srtt >> TCP_RTT_SHIFT)));
+
+                                               tcp_ccdbg_trace(tp, th,
+                                                   TCP_CC_ENTER_FASTRECOVERY);
 
                                                (void) tcp_output(tp);
                                                goto drop;
@@ -3314,13 +3751,31 @@ trimthenstep6:
                                             tp->t_maxseg * tp->t_dupacks;
                                        if (SEQ_GT(onxt, tp->snd_nxt))
                                                tp->snd_nxt = onxt;
-                                       DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                               struct tcpcb *, tp, struct tcphdr *, th,
-                                               int32_t, TCP_CC_ENTER_FASTRECOVERY);
+                                       tcp_ccdbg_trace(tp, th,
+                                           TCP_CC_ENTER_FASTRECOVERY);
                                        goto drop;
+                               } else if (limited_txmt && 
+                                       ALLOW_LIMITED_TRANSMIT(tp) &&
+                                       (!(SACK_ENABLED(tp)) || sack_bytes_acked > 0) && 
+                                       (so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)) > 0) {
+                                       u_int32_t incr = (tp->t_maxseg * tp->t_dupacks);
+
+                                       /* Use Limited Transmit algorithm on the first two
+                                        * duplicate acks when there is new data to transmit
+                                        */
+                                       tp->snd_cwnd += incr;
+                                       tcpstat.tcps_limited_txt++;
+                                       (void) tcp_output(tp);
+
+                                       tcp_ccdbg_trace(tp, th, TCP_CC_LIMITED_TRANSMIT);
+                                       
+                                       /* Reset snd_cwnd back to normal */
+                                       tp->snd_cwnd -= incr;
                                }
-                       } else
+                       } else {
                                tp->t_dupacks = 0;
+                               tp->t_rexmtthresh = tcprexmtthresh;
+                       }
                        break;
                }
                /*
@@ -3329,30 +3784,53 @@ trimthenstep6:
                 */
                if (IN_FASTRECOVERY(tp)) {
                        if (SEQ_LT(th->th_ack, tp->snd_recover)) {
-                               if (tp->sack_enable)
+                               /*
+                                * If we received an ECE and entered 
+                                * recovery, the subsequent ACKs should
+                                * not be treated as partial acks.
+                                */
+                               if (tp->ecn_flags & TE_INRECOVERY)
+                                       goto process_ACK;
+
+                               if (SACK_ENABLED(tp))
                                        tcp_sack_partialack(tp, th);
                                else
                                        tcp_newreno_partial_ack(tp, th);                        
-                               
-                               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, struct tcphdr *, th,
-                                       int32_t, TCP_CC_PARTIAL_ACK);
+                               tcp_ccdbg_trace(tp, th, TCP_CC_PARTIAL_ACK);
                        } else {
                                EXIT_FASTRECOVERY(tp);
                                if (CC_ALGO(tp)->post_fr != NULL)
                                        CC_ALGO(tp)->post_fr(tp, th);
-                               tp->t_dupacks = 0;
 
-                               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, struct tcphdr *, th,
-                                       int32_t, TCP_CC_EXIT_FASTRECOVERY);
+                               tcp_ccdbg_trace(tp, th,
+                                   TCP_CC_EXIT_FASTRECOVERY);
+                       }
+               } else if ((tp->t_flagsext & 
+                       (TF_PKTS_REORDERED|TF_DELAY_RECOVERY))
+                       == (TF_PKTS_REORDERED|TF_DELAY_RECOVERY)) {
+                       /*
+                        * If the ack acknowledges upto snd_recover or if
+                        * it acknowledges all the snd holes, exit
+                        * recovery and cancel the timer. Otherwise,
+                        * this is a partial ack. Wait for recovery timer
+                        * to enter recovery. The snd_holes have already
+                        * been updated.
+                        */
+                       if (SEQ_GEQ(th->th_ack, tp->snd_recover) ||
+                           TAILQ_EMPTY(&tp->snd_holes)) {
+                               tp->t_timer[TCPT_DELAYFR] = 0;
+                               tp->t_flagsext &= ~TF_DELAY_RECOVERY;
+                               EXIT_FASTRECOVERY(tp);
+                               tcp_ccdbg_trace(tp, th,
+                                   TCP_CC_EXIT_FASTRECOVERY);
                        }
                } else {
                        /*
-                        * We were not in fast recovery. Reset the duplicate ack
-                        * counter.
+                        * We were not in fast recovery. Reset the
+                        * duplicate ack counter.
                         */
                        tp->t_dupacks = 0;
+                       tp->t_rexmtthresh = tcprexmtthresh;
                }
 
 
@@ -3379,57 +3857,22 @@ trimthenstep6:
                }
 
 process_ACK:
-               acked = th->th_ack - tp->snd_una;
+               acked = BYTES_ACKED(th, tp);
                tcpstat.tcps_rcvackpack++;
                tcpstat.tcps_rcvackbyte += acked;
 
                /*
-                * If we just performed our first retransmit, and the ACK
-                * arrives within our recovery window, then it was a mistake
-                * to do the retransmit in the first place.  Recover our
-                * original cwnd and ssthresh, and proceed to transmit where
-                * we left off.
-                */
-               if (tp->t_rxtshift == 1 && 
-                       TSTMP_LT(tcp_now, tp->t_badrxtwin)) {
-                       ++tcpstat.tcps_sndrexmitbad;
-                       tp->snd_cwnd = tp->snd_cwnd_prev;
-                       tp->snd_ssthresh = tp->snd_ssthresh_prev;
-                       tp->snd_recover = tp->snd_recover_prev;
-                       if (tp->t_flags & TF_WASFRECOVERY)
-                               ENTER_FASTRECOVERY(tp);
-                       tp->snd_nxt = tp->snd_max;
-                       tp->t_badrxtwin = 0;    /* XXX probably not required */ 
-                       tp->t_rxtshift = 0;
-                       tp->rxt_start = 0;
-                       tcp_bad_rexmt_fix_sndbuf(tp);
-
-                       DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                               struct tcpcb *, tp, struct tcphdr *, th,
-                               int32_t, TCP_CC_BAD_REXMT_RECOVERY);
-               }
-
-               /*
-                * If we have a timestamp reply, update smoothed
-                * round trip time.  If no timestamp is present but
-                * transmit timer is running and timed sequence
-                * number was acked, update smoothed round trip time.
-                * Since we now have an rtt measurement, cancel the
-                * timer backoff (cf., Phil Karn's retransmit alg.).
-                * Recompute the initial retransmit timer.
-                * Also makes sure we have a valid time stamp in hand
+                * If the last packet was a retransmit, make sure
+                * it was not spurious.
                 *
-                * Some boxes send broken timestamp replies
-                * during the SYN+ACK phase, ignore
-                * timestamps of 0 or we could calculate a
-                * huge RTT and blow up the retransmit timer.
+                * This will also take care of congestion window
+                * adjustment if a last packet was recovered due to a
+                * tail loss probe.
                 */
-               if (((to.to_flags & TOF_TS) != 0) && (to.to_tsecr != 0) &&
-                       TSTMP_GEQ(tcp_now, to.to_tsecr)) {
-                       tcp_xmit_timer(tp, tcp_now - to.to_tsecr);
-               } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
-                       tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
-               }
+               tcp_bad_rexmt_check(tp, th, &to);
+
+               /* Recalculate the RTT */
+               tcp_compute_rtt(tp, &to, th);
 
                /*
                 * If all outstanding data is acked, stop retransmit
@@ -3439,28 +3882,30 @@ process_ACK:
                 */
                if (th->th_ack == tp->snd_max) {
                        tp->t_timer[TCPT_REXMT] = 0;
+                       tp->t_timer[TCPT_PTO] = 0;
                        needoutput = 1;
                } else if (tp->t_timer[TCPT_PERSIST] == 0)
-                       tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur);
+                       tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp,
+                           tp->t_rxtcur);
 
                /*
-                * If no data (only SYN) was ACK'd,
-                *    skip rest of ACK processing.
+                * If no data (only SYN) was ACK'd, skip rest of ACK
+                * processing.
                 */
                if (acked == 0)
                        goto step6;
 
+
                if ((thflags & TH_ECE) != 0 &&
                        ((tp->ecn_flags & TE_ECN_ON) == TE_ECN_ON)) {
                        /*
-                        * Reduce the congestion window if we haven't done so.
+                        * Reduce the congestion window if we haven't
+                        * done so.
                         */
-                       if (!tp->sack_enable && !IN_FASTRECOVERY(tp) &&
-                               SEQ_GEQ(th->th_ack, tp->snd_recover)) {
+                       if (!IN_FASTRECOVERY(tp)) {
                                tcp_reduce_congestion_window(tp);
-                               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, struct tcphdr *, th, 
-                                       int32_t, TCP_CC_ECN_RCVD);
+                               tp->ecn_flags |= (TE_INRECOVERY|TE_SENDCWR);
+                               tcp_ccdbg_trace(tp, th, TCP_CC_ECN_RCVD);
                        }
                }
 
@@ -3475,17 +3920,22 @@ process_ACK:
                if (!IN_FASTRECOVERY(tp)) {
                        if (CC_ALGO(tp)->ack_rcvd != NULL)
                                CC_ALGO(tp)->ack_rcvd(tp, th);
-                       
-                       DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                               struct tcpcb *, tp, struct tcphdr *, th,
-                               int32_t, TCP_CC_ACK_RCVD);
+                       tcp_ccdbg_trace(tp, th, TCP_CC_ACK_RCVD);
                }
                if (acked > so->so_snd.sb_cc) {
                        tp->snd_wnd -= so->so_snd.sb_cc;
                        sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
+                       if (so->so_flags & SOF_ENABLE_MSGS) {
+                               so->so_msg_state->msg_serial_bytes -= 
+                                       (int)so->so_snd.sb_cc;
+                       }
                        ourfinisacked = 1;
                } else {
                        sbdrop(&so->so_snd, acked);
+                       if (so->so_flags & SOF_ENABLE_MSGS) {
+                               so->so_msg_state->msg_serial_bytes -= 
+                                       acked;
+                       }
                        tcp_sbsnd_trim(&so->so_snd);
                        tp->snd_wnd -= acked;
                        ourfinisacked = 0;
@@ -3501,7 +3951,7 @@ process_ACK:
                        EXIT_FASTRECOVERY(tp);
 
                tp->snd_una = th->th_ack;
-               if (tp->sack_enable) {
+               if (SACK_ENABLED(tp)) {
                        if (SEQ_GT(tp->snd_una, tp->snd_recover))
                                tp->snd_recover = tp->snd_una;
                }
@@ -3529,19 +3979,24 @@ process_ACK:
                                /*
                                 * If we can't receive any more
                                 * data, then closing user can proceed.
-                                * Starting the timer is contrary to the
+                                * Starting the TCPT_2MSL timer is contrary to the
                                 * specification, but if we don't get a FIN
                                 * we'll hang forever.
                                 */
                                if (so->so_state & SS_CANTRCVMORE) {
-                                       add_to_time_wait(tp, tcp_maxidle);
+                                       tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp,
+                                               TCP_CONN_MAXIDLE(tp));
                                        isconnected = FALSE;
                                        isdisconnected = TRUE;
                                }
-                               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_2);
+                               DTRACE_TCP4(state__change, void, NULL, 
+                                       struct inpcb *, inp,
+                                       struct tcpcb *, tp, 
+                                       int32_t, TCPS_FIN_WAIT_2);
                                tp->t_state = TCPS_FIN_WAIT_2;
-                               /* fall through and make sure we also recognize data ACKed with the FIN */
+                               /* fall through and make sure we also recognize 
+                                * data ACKed with the FIN 
+                                */
                        }
                        tp->t_flags |= TF_ACKNOW;
                        break;
@@ -3554,16 +4009,17 @@ process_ACK:
                 */
                case TCPS_CLOSING:
                        if (ourfinisacked) {
-                               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
-                                       struct tcpcb *, tp, int32_t, TCPS_TIME_WAIT);
+                               DTRACE_TCP4(state__change, void, NULL, 
+                                       struct inpcb *, inp,
+                                       struct tcpcb *, tp, 
+                                       int32_t, TCPS_TIME_WAIT);
                                tp->t_state = TCPS_TIME_WAIT;
                                tcp_canceltimers(tp);
-                               /* Shorten TIME_WAIT [RFC-1644, p.28] */
-                               if (tp->cc_recv != 0 &&
-                                   ((int)(tcp_now - tp->t_starttime)) < tcp_msl)
-                                       add_to_time_wait(tp, tp->t_rxtcur * TCPTV_TWTRUNC);
-                               else
+                               if (tp->t_flagsext & TF_NOTIMEWAIT) {
+                                       tp->t_flags |= TF_CLOSING;
+                               } else {
                                        add_to_time_wait(tp, 2 * tcp_msl);
+                               }
                                isconnected = FALSE;
                                isdisconnected = TRUE;
                        }
@@ -3592,6 +4048,26 @@ process_ACK:
                        add_to_time_wait(tp, 2 * tcp_msl);
                        goto dropafterack;
                }
+
+               /*
+                * If there is a SACK option on the ACK and we 
+                * haven't seen any duplicate acks before, count
+                * it as a duplicate ack even if the cumulative
+                * ack is advanced. If the receiver delayed an
+                * ack and detected loss afterwards, then the ack
+                * will advance cumulative ack and will also have 
+                * a SACK option. So counting it as one duplicate
+                * ack is ok.
+                */ 
+               if (sack_ackadv == 1 &&
+                   tp->t_state == TCPS_ESTABLISHED && 
+                   SACK_ENABLED(tp) && sack_bytes_acked > 0 && 
+                   to.to_nsacks > 0 && tp->t_dupacks == 0 &&
+                   SEQ_LEQ(th->th_ack, tp->snd_una) && tlen == 0 &&
+                   !(tp->t_flagsext & TF_PKTS_REORDERED)) {
+                       tcpstat.tcps_sack_ackadv++;
+                       goto process_dupack;
+               }
        }
 
 step6:
@@ -3727,11 +4203,21 @@ dodata:
                    LIST_EMPTY(&tp->t_segq) &&
                    TCPS_HAVEESTABLISHED(tp->t_state)) {
                        TCP_INC_VAR(tp->t_unacksegs, nlropkts);
+                       /*
+                        * Calculate the RTT on the receiver only if the 
+                        * connection is in streaming mode and the last 
+                        * packet was not an end-of-write
+                        */
+                       if ((tp->t_flags & TF_STRETCHACK) &&
+                               !(tp->t_flagsext & TF_STREAMEOW))
+                               tcp_compute_rtt(tp, &to, th);
+                       
                        if (DELAY_ACK(tp, th) && 
                                ((tp->t_flags & TF_ACKNOW) == 0) ) {
                                if ((tp->t_flags & TF_DELACK) == 0) {
                                        tp->t_flags |= TF_DELACK;
-                                       tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack);
+                                       tp->t_timer[TCPT_DELACK] = 
+                                               OFFSET_FROM_START(tp, tcp_delack);
                                }
                        }         
                        else {
@@ -3742,27 +4228,33 @@ dodata:
                        TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts);
                        tcpstat.tcps_rcvbyte += tlen;
                        if (nstat_collect) {
-                               if (m->m_pkthdr.aux_flags & MAUXF_SW_LRO_PKT) {
-                                       locked_add_64(&inp->inp_stat->rxpackets, m->m_pkthdr.lro_npkts);
-                               } else { 
-                                       locked_add_64(&inp->inp_stat->rxpackets, 1);
+                               if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) {
+                                       INP_ADD_STAT(inp, cell, wifi, wired, 
+                                           rxpackets, m->m_pkthdr.lro_npkts);
+                               } else {
+                                       INP_ADD_STAT(inp, cell, wifi, wired,
+                                           rxpackets, 1);
                                }
-                               locked_add_64(&inp->inp_stat->rxbytes, tlen);
+                               INP_ADD_STAT(inp, cell, wifi, wired,
+                                   rxbytes, tlen);
                        }
-                       ND6_HINT(tp);
-                       
                        tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen);
                        so_recv_data_stat(so, m, drop_hdrlen);
-                       if (sbappendstream(&so->so_rcv, m))
+                       
+                       if (sbappendstream_rcvdemux(so, m,
+                           th->th_seq - (tp->irs + 1), 0)) {
                                sorwakeup(so);
+                       }
                } else {
-                       thflags = tcp_reass(tp, th, &tlen, m);
+                       thflags = tcp_reass(tp, th, &tlen, m, ifp);
                        tp->t_flags |= TF_ACKNOW;
                }
 
-               if (tlen > 0 && tp->sack_enable)
+               if (tlen > 0 && SACK_ENABLED(tp))
                        tcp_update_sack_list(tp, save_start, save_end);
 
+               tcp_adaptive_rwtimo_check(tp, tlen);
+
                if (tp->t_flags & TF_DELACK) 
                {
 #if INET6
@@ -3842,20 +4334,18 @@ dodata:
                 * standard timers.
                 */
                case TCPS_FIN_WAIT_2:
-                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
-                               struct tcpcb *, tp, int32_t, TCPS_TIME_WAIT);
+                       DTRACE_TCP4(state__change, void, NULL, 
+                               struct inpcb *, inp,
+                               struct tcpcb *, tp, 
+                               int32_t, TCPS_TIME_WAIT);
                        tp->t_state = TCPS_TIME_WAIT;
                        tcp_canceltimers(tp);
-                       /* Shorten TIME_WAIT [RFC-1644, p.28] */
-                       if (tp->cc_recv != 0 &&
-                               ((int)(tcp_now - tp->t_starttime)) < tcp_msl) {
-                               add_to_time_wait(tp, tp->t_rxtcur * TCPTV_TWTRUNC);
-                               /* For transaction client, force ACK now. */
-                               tp->t_flags |= TF_ACKNOW;
-                               tp->t_unacksegs = 0;
-                       }
-                       else
+                       tp->t_flags |= TF_ACKNOW;
+                       if (tp->t_flagsext & TF_NOTIMEWAIT) {
+                               tp->t_flags |= TF_CLOSING;
+                       } else {
                                add_to_time_wait(tp, 2 * tcp_msl);
+                       }
                        soisdisconnected(so);
                        break;
 
@@ -3907,10 +4397,7 @@ dropafterack:
            (SEQ_GT(tp->snd_una, th->th_ack) ||
             SEQ_GT(th->th_ack, tp->snd_max)) ) {
                rstreason = BANDLIM_RST_OPENPORT;
-               
-               if (ifp != NULL && ifp->if_tcp_stat != NULL)
-                       atomic_add_64(&ifp->if_tcp_stat->dospacket, 1);
-                       
+               IF_TCP_STATINC(ifp, dospacket);
                goto dropwithreset;
        }
 #if TCPDEBUG
@@ -3963,23 +4450,25 @@ dropwithreset:
                tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
                          &tcp_savetcp, 0);
 #endif
+       bzero(&tra, sizeof(tra));
+       tra.ifscope = ifscope;
+       tra.awdl_unrestricted = 1;
        if (thflags & TH_ACK)
                /* mtod() below is safe as long as hdr dropping is delayed */
                tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack,
-                   TH_RST, ifscope, nocell);
+                   TH_RST, &tra);
        else {
                if (thflags & TH_SYN)
                        tlen++;
                /* mtod() below is safe as long as hdr dropping is delayed */
                tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen,
-                   (tcp_seq)0, TH_RST|TH_ACK, ifscope, nocell);
+                   (tcp_seq)0, TH_RST|TH_ACK, &tra);
        }
        /* destroy temporarily created socket */
        if (dropsocket) {
                (void) soabort(so); 
                tcp_unlock(so, 1, 0);
-       }
-       else if ((inp != NULL) && (nosock == 0)) {
+       } else if ((inp != NULL) && (nosock == 0)) {
                tcp_unlock(so, 1, 0);
        }
        KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0);
@@ -4047,11 +4536,7 @@ tcp_dooptions(tp, cp, cnt, th, to, input_ifscope)
                        if (!(th->th_flags & TH_SYN))
                                continue;
                        bcopy((char *) cp + 2, (char *) &mss, sizeof(mss));
-
-#if BYTE_ORDER != BIG_ENDIAN
                        NTOHS(mss);
-#endif
-
                        break;
 
                case TCPOPT_WINDOW:
@@ -4059,6 +4544,7 @@ tcp_dooptions(tp, cp, cnt, th, to, input_ifscope)
                                continue;
                        if (!(th->th_flags & TH_SYN))
                                continue;
+                       to->to_flags |= TOF_SCALE;
                        tp->t_flags |= TF_RCVD_SCALE;
                        tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
                        break;
@@ -4069,18 +4555,10 @@ tcp_dooptions(tp, cp, cnt, th, to, input_ifscope)
                        to->to_flags |= TOF_TS;
                        bcopy((char *)cp + 2,
                            (char *)&to->to_tsval, sizeof(to->to_tsval));
-
-#if BYTE_ORDER != BIG_ENDIAN
                        NTOHL(to->to_tsval);
-#endif
-
                        bcopy((char *)cp + 6,
                            (char *)&to->to_tsecr, sizeof(to->to_tsecr));
-
-#if BYTE_ORDER != BIG_ENDIAN
                        NTOHL(to->to_tsecr);
-#endif
-
                        /*
                         * A timestamp received in a SYN makes
                         * it ok to send timestamp requests and replies.
@@ -4106,6 +4584,12 @@ tcp_dooptions(tp, cp, cnt, th, to, input_ifscope)
                        tcpstat.tcps_sack_rcv_blocks++;
 
                        break;
+               
+#if MPTCP
+               case TCPOPT_MULTIPATH:
+                       tcp_do_mptcp_options(tp, cp, th, to, optlen);
+                       break;
+#endif /* MPTCP */
                }
        }
        if (th->th_flags & TH_SYN)
@@ -4166,8 +4650,24 @@ get_base_rtt(struct tcpcb *tp)
 void
 update_base_rtt(struct tcpcb *tp, uint32_t rtt)
 {
+       int32_t i, qdelay;
+       u_int32_t base_rtt;
+
        if (++tp->rtt_count >= rtt_samples_per_slot) {
-               int i=0;
+#if TRAFFIC_MGT
+               /*
+                * If the recv side is being throttled, check if the 
+                * current RTT is closer to the base RTT seen in 
+                * first (recent) two slots. If so, unthrottle the stream.
+                */
+               if (tp->t_flagsext & TF_RECV_THROTTLE) {
+                       base_rtt = min(tp->rtt_hist[0], tp->rtt_hist[1]);
+                       qdelay = tp->t_rttcur - base_rtt;
+                       if (qdelay < target_qdelay)
+                               tp->t_flagsext &= ~(TF_RECV_THROTTLE);
+               }
+#endif /* TRAFFIC_MGT */
+
                for (i = (N_RTT_BASE-1); i > 0; --i) {
                        tp->rtt_hist[i] = tp->rtt_hist[i-1];
                }
@@ -4178,17 +4678,69 @@ update_base_rtt(struct tcpcb *tp, uint32_t rtt)
        }
 }
 
+/*
+ * If we have a timestamp reply, update smoothed RTT. If no timestamp is
+ * present but transmit timer is running and timed sequence number was 
+ * acked, update smoothed RTT. 
+ *
+ * If timestamps are supported, a receiver can update RTT even if
+ * there is no outstanding data.
+ *
+ * Some boxes send broken timestamp replies during the SYN+ACK phase,
+ * ignore timestamps of 0or we could calculate a huge RTT and blow up 
+ * the retransmit timer.
+ */
+static void
+tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th)
+{
+       VERIFY(to != NULL && th != NULL);
+       if (((to->to_flags & TOF_TS) != 0) && 
+               (to->to_tsecr != 0) &&
+               TSTMP_GEQ(tcp_now, to->to_tsecr)) {
+               tcp_xmit_timer(tp, tcp_now - to->to_tsecr, 
+                       to->to_tsecr, th->th_ack);
+       } else if (tp->t_rtttime != 0 && SEQ_GT(th->th_ack, tp->t_rtseq)) {
+               tcp_xmit_timer(tp, tcp_now - tp->t_rtttime, 0,
+                       th->th_ack);
+       }
+}
+
 /*
  * Collect new round-trip time estimate
  * and update averages and current timeout.
  */
 static void
-tcp_xmit_timer(tp, rtt)
-       register struct tcpcb *tp;
-       int rtt;
+tcp_xmit_timer(register struct tcpcb *tp, int rtt, 
+       u_int32_t tsecr, tcp_seq th_ack)
 {
        register int delta;
 
+       if (tp->t_flagsext & TF_RECOMPUTE_RTT) {
+               if (SEQ_GT(th_ack, tp->snd_una) &&
+                   SEQ_LEQ(th_ack, tp->snd_max) &&
+                   (tsecr == 0 ||
+                   TSTMP_GEQ(tsecr, tp->t_badrexmt_time))) {
+                       /*
+                        * We received a new ACk after a
+                        * spurious timeout. Adapt retransmission 
+                        * timer as described in rfc 4015.
+                        */
+                       tp->t_flagsext &= ~(TF_RECOMPUTE_RTT);
+                       tp->t_badrexmt_time = 0;
+                       tp->t_srtt = max(tp->t_srtt_prev, rtt);
+                       tp->t_srtt = tp->t_srtt << TCP_RTT_SHIFT;
+                       tp->t_rttvar = max(tp->t_rttvar_prev, (rtt >> 1));
+                       tp->t_rttvar = tp->t_rttvar << TCP_RTTVAR_SHIFT;
+
+                       if (tp->t_rttbest > (tp->t_srtt + tp->t_rttvar))
+                               tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
+
+                       goto compute_rto;
+               } else {
+                       return;
+               }
+       }
+
        tcpstat.tcps_rttupdated++;
        tp->t_rttupdated++;
 
@@ -4205,9 +4757,10 @@ tcp_xmit_timer(tp, rtt)
                 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
                 * point).
                 *
-                * Freebsd adjusts rtt to origin 0 by subtracting 1 from the provided
-                * rtt value. This was required because of the way t_rtttime was
-                * initiailised to 1 before. Since we changed t_rtttime to be based on
+                * Freebsd adjusts rtt to origin 0 by subtracting 1 
+                * from the provided rtt value. This was required because 
+                * of the way t_rtttime was initiailised to 1 before. 
+                * Since we changed t_rtttime to be based on
                 * tcp_now, this extra adjustment is not needed.
                 */
                delta = (rtt << TCP_DELTA_SHIFT)
@@ -4243,10 +4796,13 @@ tcp_xmit_timer(tp, rtt)
                tp->t_srtt = rtt << TCP_RTT_SHIFT;
                tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
        }
-       nstat_route_rtt(tp->t_inpcb->inp_route.ro_rt, tp->t_srtt, tp->t_rttvar);
+
+compute_rto:
+       nstat_route_rtt(tp->t_inpcb->inp_route.ro_rt, tp->t_srtt, 
+               tp->t_rttvar);
        tp->t_rtttime = 0;
        tp->t_rxtshift = 0;
-       tp->rxt_start = 0;
+       tp->t_rxtstart = 0;
 
        /*
         * the retransmit should happen at rtt + 4 * rttvar.
@@ -4323,9 +4879,9 @@ tcp_maxmtu6(struct rtentry *rt)
  * size (usually 512 or the default IP max size, but no more than the mtu
  * of the interface), as we can't discover anything about intervening
  * gateways or networks.  We also initialize the congestion/slow start
- * window to be a single segment if the destination isn't local.
- * While looking at the routing entry, we also initialize other path-dependent
- * parameters from pre-set or cached values in the routing entry.
+ * window. While looking at the routing entry, we also initialize 
+ * other path-dependent parameters from pre-set or cached values 
+ * in the routing entry.
  *
  * Also take into account the space needed for options that we
  * send regularly.  Make maxseg shorter by that amount to assure
@@ -4370,24 +4926,11 @@ tcp_mss(tp, offer, input_ifscope)
 #if INET6
        if (isipv6) {
                rt = tcp_rtlookup6(inp, input_ifscope);
-               if (rt != NULL &&
-                   (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;
-               }
        }
        else
 #endif /* INET6 */
        {
                rt = tcp_rtlookup(inp, input_ifscope);
-               if (rt != NULL &&
-                   (rt->rt_gateway->sa_family == AF_LINK ||
-                   rt->rt_ifp->if_flags & IFF_LOOPBACK ||
-                   in_localaddr(inp->inp_faddr))) {
-                       tp->t_flags |= TF_LOCAL;
-               }
        }
        isnetlocal = (tp->t_flags & TF_LOCAL);
 
@@ -4402,9 +4945,10 @@ tcp_mss(tp, offer, input_ifscope)
        ifp = rt->rt_ifp;
        /*
         * Slower link window correction:
-        * If a value is specificied for slowlink_wsize use it for PPP links
-        * believed to be on a serial modem (speed <128Kbps). Excludes 9600bps as
-        * it is the default value adversized by pseudo-devices over ppp.
+        * If a value is specificied for slowlink_wsize use it for
+        * PPP links believed to be on a serial modem (speed <128Kbps).
+        * Excludes 9600bps as it is the default value adversized
+        * by pseudo-devices over ppp.
         */
        if (ifp->if_type == IFT_PPP && slowlink_wsize > 0 && 
            ifp->if_baudrate > 9600 && ifp->if_baudrate <= 128000) {
@@ -4492,8 +5036,12 @@ tcp_mss(tp, offer, input_ifscope)
            (origoffer == -1 ||
             (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
                mss -= TCPOLEN_TSTAMP_APPA;
-       tp->t_maxseg = mss;
 
+#if MPTCP
+       mss -= mptcp_adj_mss(tp, FALSE);
+#endif /* MPTCP */
+       tp->t_maxseg = mss;
+       
        /*
         * Calculate corrected value for sb_max; ensure to upgrade the
         * numerator for large sb_max values else it will overflow.
@@ -4540,8 +5088,8 @@ tcp_mss(tp, offer, input_ifscope)
                /*
                 * There's some sort of gateway or interface
                 * buffer limit on the path.  Use this to set
-                * the slow start threshhold, but set the
-                * threshold to no less than 2*mss.
+                * slow-start threshold, but set the threshold to
+                * no less than 2*mss.
                 */
                tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
                tcpstat.tcps_usedssthresh++;
@@ -4549,7 +5097,6 @@ tcp_mss(tp, offer, input_ifscope)
                tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
        }
 
-
        /*
         * Set the slow-start flight size depending on whether this
         * is a local network or not.
@@ -4557,8 +5104,7 @@ tcp_mss(tp, offer, input_ifscope)
        if (CC_ALGO(tp)->cwnd_init != NULL)
                CC_ALGO(tp)->cwnd_init(tp);
 
-       DTRACE_TCP5(cc, void, NULL, struct inpcb *, tp->t_inpcb, struct tcpcb *, tp,
-               struct tcphdr *, NULL, int32_t, TCP_CC_CWND_INIT);
+       tcp_ccdbg_trace(tp, NULL, TCP_CC_CWND_INIT);
 
        /* Route locked during lookup above */
        RT_UNLOCK(rt);
@@ -4634,6 +5180,7 @@ tcp_newreno_partial_ack(tp, th)
                tcp_seq onxt = tp->snd_nxt;
                u_int32_t  ocwnd = tp->snd_cwnd;
                tp->t_timer[TCPT_REXMT] = 0;
+               tp->t_timer[TCPT_PTO] = 0;
                tp->t_rtttime = 0;
                tp->snd_nxt = th->th_ack;
                /*
@@ -4641,7 +5188,7 @@ tcp_newreno_partial_ack(tp, th)
                 * (tp->snd_una has not yet been updated when this function 
                 *  is called)
                 */
-               tp->snd_cwnd = tp->t_maxseg + (th->th_ack - tp->snd_una);
+               tp->snd_cwnd = tp->t_maxseg + BYTES_ACKED(th, tp);
                tp->t_flags |= TF_ACKNOW;
                (void) tcp_output(tp);
                tp->snd_cwnd = ocwnd;
@@ -4651,8 +5198,8 @@ tcp_newreno_partial_ack(tp, th)
                 * Partial window deflation.  Relies on fact that tp->snd_una
                 * not updated yet.
                 */
-               if (tp->snd_cwnd > th->th_ack - tp->snd_una)
-                       tp->snd_cwnd -= th->th_ack - tp->snd_una;
+               if (tp->snd_cwnd > BYTES_ACKED(th, tp))
+                       tp->snd_cwnd -= BYTES_ACKED(th, tp);
                else
                        tp->snd_cwnd = 0;
                tp->snd_cwnd += tp->t_maxseg;
@@ -4673,29 +5220,61 @@ tcp_dropdropablreq(struct socket *head)
 {
        struct socket *so, *sonext;
        unsigned int i, j, qlen;
-       static int rnd;
-       static struct timeval old_runtime;
+       static u_int32_t rnd = 0;
+       static u_int64_t old_runtime;
        static unsigned int cur_cnt, old_cnt;
-       struct timeval tv;
+       u_int64_t now_sec;
        struct inpcb *inp = NULL;
        struct tcpcb *tp;
 
        if ((head->so_options & SO_ACCEPTCONN) == 0)
-               return 0;
+               return (0);
+
+       if (TAILQ_EMPTY(&head->so_incomp))
+               return (0);
+
+       /* 
+        * Check if there is any socket in the incomp queue
+        * that is closed because of a reset from the peer and is
+        * waiting to be garbage collected. If so, pick that as
+        * the victim
+        */
+       TAILQ_FOREACH_SAFE(so, &head->so_incomp, so_list, sonext) {
+               inp = sotoinpcb(so);
+               tp = intotcpcb(inp);
+               if (tp != NULL && tp->t_state == TCPS_CLOSED &&
+                   so->so_head != NULL &&
+                   (so->so_state & (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE)) ==
+                   (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE)) {
+                       /* 
+                        * The listen socket is already locked but we 
+                        * can lock this socket here without lock ordering
+                        * issues because it is in the incomp queue and
+                        * is not visible to others.
+                        */
+                       if (lck_mtx_try_lock(&inp->inpcb_mtx)) {
+                               so->so_usecount++;
+                               goto found_victim;
+                       } else {
+                               continue;
+                       }
+               }
+       }
 
        so = TAILQ_FIRST(&head->so_incomp);
-       if (!so)
-               return 0;
 
-       microtime(&tv);
-       if ((i = (tv.tv_sec - old_runtime.tv_sec)) != 0) {
-               old_runtime = tv;
+       now_sec = net_uptime();
+       if ((i = (now_sec - old_runtime)) != 0) {
+               old_runtime = now_sec;
                old_cnt = cur_cnt / i;
                cur_cnt = 0;
        }
        
        
        qlen = head->so_incqlen;
+       if (rnd == 0)
+               rnd = RandomULong();
+
        if (++cur_cnt > qlen || old_cnt > qlen) {
                rnd = (314159 * rnd + 66329) & 0xffff;
                j = ((qlen + 1) * rnd) >> 16;
@@ -4709,25 +5288,34 @@ tcp_dropdropablreq(struct socket *head)
                
                sonext = TAILQ_NEXT(so, so_list);
 
-               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) != WNT_STOPUSING) {
-                       /* Avoid the issue of a socket being accepted by one input thread
-                        * and being dropped by another input thread.
-                        * If we can't get a hold on this mutex, then grab the next socket in line.
+               if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) 
+                       != WNT_STOPUSING) {
+                       /* 
+                        * Avoid the issue of a socket being accepted
+                        * by one input thread and being dropped by 
+                        * another input thread. If we can't get a hold 
+                        * on this mutex, then grab the next socket in 
+                        * line.
                         */
                        if (lck_mtx_try_lock(&inp->inpcb_mtx)) {
                                so->so_usecount++;
                                if ((so->so_usecount == 2) && 
-                                   (so->so_state & SS_INCOMP) != 0 &&
-                                   (so->so_flags & SOF_INCOMP_INPROGRESS) == 0) 
+                                   (so->so_state & SS_INCOMP) &&
+                                   !(so->so_flags & SOF_INCOMP_INPROGRESS))  {
                                        break;
-                               else {/* don't use if being accepted or used in any other way */
+                               } else {
+                                       /* 
+                                        * don't use if being accepted or 
+                                        * used in any other way
+                                        */
                                        in_pcb_checkstate(inp, WNT_RELEASE, 1);
                                        tcp_unlock(so, 1, 0);
                                }
-                       }
-                       else {
-                               /* do not try to lock the inp in in_pcb_checkstate
-                                * because the lock is already held in some other thread.
+                       } else {
+                               /* 
+                                * do not try to lock the inp in 
+                                * in_pcb_checkstate because the lock 
+                                * is already held in some other thread.
                                 * Only drop the inp_wntcnt reference.
                                 */
                                in_pcb_checkstate(inp, WNT_RELEASE, 1);
@@ -4736,20 +5324,22 @@ tcp_dropdropablreq(struct socket *head)
                so = sonext;
                
        }
-       if (!so)
-               return 0;
+       if (so == NULL) {
+               return (0);
+       }
 
        /* Makes sure socket is still in the right state to be discarded */
 
        if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
                tcp_unlock(so, 1, 0);
-               return 0;
+               return (0);
        }
 
+found_victim:
        if (so->so_usecount != 2 || !(so->so_state & SS_INCOMP)) {
                /* do not discard: that socket is being accepted */
                tcp_unlock(so, 1, 0);
-               return 0;
+               return (0);
        }
 
        TAILQ_REMOVE(&head->so_incomp, so, so_list);
@@ -4761,35 +5351,38 @@ tcp_dropdropablreq(struct socket *head)
        so->so_head = NULL;
 
        tcp_close(tp);
-       tp->t_unacksegs = 0;
-
        if (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING) {
-               /* Some one has a wantcnt on this pcb. Since WNT_ACQUIRE
+               /* 
+                * Some one has a wantcnt on this pcb. Since WNT_ACQUIRE
                 * doesn't require a lock, it could have happened while
                 * we are holding the lock. This pcb will have to
                 * be garbage collected later.
                 * Release the reference held for so_incomp queue
                 */
                so->so_usecount--;
-
                tcp_unlock(so, 1, 0);
        } else {
-               /* Unlock this socket and leave the reference on. We need to
-                * acquire the pcbinfo lock in order to fully dispose it off 
+               /* 
+                * Unlock this socket and leave the reference on. 
+                * We need to acquire the pcbinfo lock in order to 
+                * fully dispose it off 
                 */
                tcp_unlock(so, 0, 0);
 
-               lck_rw_lock_exclusive(tcbinfo.mtx);
+               lck_rw_lock_exclusive(tcbinfo.ipi_lock);
 
                tcp_lock(so, 0, 0);
                /* Release the reference held for so_incomp queue */
                so->so_usecount--;
 
                if (so->so_usecount != 1 || 
-                   (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING)) {
-                       /* There is an extra wantcount or usecount that must
-                        * have been added when the socket was unlocked. This
-                        * socket will have to be garbage collected later
+                   (inp->inp_wantcnt > 0 && 
+                   inp->inp_wantcnt != WNT_STOPUSING)) {
+                       /* 
+                        * There is an extra wantcount or usecount 
+                        * that must have been added when the socket 
+                        * was unlocked. This socket will have to be 
+                        * garbage collected later
                         */
                        tcp_unlock(so, 1, 0);
                } else {
@@ -4799,7 +5392,7 @@ tcp_dropdropablreq(struct socket *head)
 
                        in_pcbdispose(inp);
                }
-               lck_rw_done(tcbinfo.mtx);
+               lck_rw_done(tcbinfo.ipi_lock);
        }
        tcpstat.tcps_drops++;
 
@@ -4820,7 +5413,10 @@ tcp_set_background_cc(struct socket *so)
 void
 tcp_set_foreground_cc(struct socket *so)
 {
-       tcp_set_new_cc(so, TCP_CC_ALGO_NEWRENO_INDEX);
+       if (tcp_use_newreno)
+               tcp_set_new_cc(so, TCP_CC_ALGO_NEWRENO_INDEX);
+       else
+               tcp_set_new_cc(so, TCP_CC_ALGO_CUBIC_INDEX);
 }
 
 static void
@@ -4828,7 +5424,7 @@ tcp_set_new_cc(struct socket *so, uint16_t cc_index)
 {
        struct inpcb *inp = sotoinpcb(so);
        struct tcpcb *tp = intotcpcb(inp);
-       uint16_t old_cc_index = 0;
+       u_char old_cc_index = 0;
        if (tp->tcp_cc_index != cc_index) {
 
                old_cc_index = tp->tcp_cc_index;
@@ -4837,20 +5433,12 @@ tcp_set_new_cc(struct socket *so, uint16_t cc_index)
                        CC_ALGO(tp)->cleanup(tp);
                tp->tcp_cc_index = cc_index;
 
-               /* Decide if the connection is just starting or if
-                * we have sent some packets on it.
-                */
-               if (tp->snd_nxt > tp->iss) {
-                       /* Already sent some packets */
-                       if (CC_ALGO(tp)->switch_to != NULL)
-                               CC_ALGO(tp)->switch_to(tp, old_cc_index);
-               } else {        
-                       if (CC_ALGO(tp)->init != NULL)
-                               CC_ALGO(tp)->init(tp);
-               }
-               DTRACE_TCP5(cc, void, NULL, struct inpcb *, inp,
-                       struct tcpcb *, tp, struct tcphdr *, NULL,
-                       int32_t, TCP_CC_CHANGE_ALGO);
+               tcp_cc_allocate_state(tp);
+
+               if (CC_ALGO(tp)->switch_to != NULL)
+                       CC_ALGO(tp)->switch_to(tp, old_cc_index);
+
+               tcp_ccdbg_trace(tp, NULL, TCP_CC_CHANGE_ALGO);
        }
 }
 
@@ -4859,6 +5447,9 @@ tcp_set_recv_bg(struct socket *so)
 {
        if (!IS_TCP_RECV_BG(so))
                so->so_traffic_mgt_flags |= TRAFFIC_MGT_TCP_RECVBG;
+
+       /* Unset Large Receive Offload on background sockets */
+       so_set_lro(so, SO_TC_BK);
 }
 
 void
@@ -4866,6 +5457,12 @@ tcp_clear_recv_bg(struct socket *so)
 {
        if (IS_TCP_RECV_BG(so))
                so->so_traffic_mgt_flags &= ~(TRAFFIC_MGT_TCP_RECVBG);
+
+       /* 
+        * Set/unset use of Large Receive Offload depending on 
+        * the traffic class
+        */
+       so_set_lro(so, so->so_traffic_class);
 }
 
 void
@@ -4901,7 +5498,7 @@ inp_fc_unthrottle_tcp(struct inpcb *inp)
         */
        tcp_output(tp);
 }
-
+    
 static int
 tcp_getstat SYSCTL_HANDLER_ARGS
 {
@@ -4909,6 +5506,41 @@ tcp_getstat SYSCTL_HANDLER_ARGS
 
        int error;
 
+       proc_t caller = PROC_NULL;
+       proc_t caller_parent = PROC_NULL;
+       char command_name[MAXCOMLEN + 1] = "";
+       char parent_name[MAXCOMLEN + 1] = "";
+
+       if ((caller = proc_self()) != PROC_NULL) {
+               /* get process name */
+               strlcpy(command_name, caller->p_comm, sizeof(command_name));
+
+               /* get parent process name if possible */
+               if ((caller_parent = proc_find(caller->p_ppid)) != PROC_NULL) {
+                       strlcpy(parent_name, caller_parent->p_comm,
+                           sizeof(parent_name));
+                       proc_rele(caller_parent);
+               }
+
+               if ((escape_str(command_name, strlen(command_name),
+                   sizeof(command_name)) == 0) &&
+                   (escape_str(parent_name, strlen(parent_name),
+                   sizeof(parent_name)) == 0)) {
+                       kern_asl_msg(LOG_DEBUG, "messagetracer",
+                           5,
+                           "com.apple.message.domain",
+                           "com.apple.kernel.tcpstat", /* 1 */
+                           "com.apple.message.signature",
+                           "tcpstat", /* 2 */
+                           "com.apple.message.signature2", command_name, /* 3 */
+                           "com.apple.message.signature3", parent_name, /* 4 */
+                           "com.apple.message.summarize", "YES", /* 5 */
+                           NULL);
+               }
+       }
+       if (caller != PROC_NULL)
+               proc_rele(caller);
+
        if (req->oldptr == 0) {
                req->oldlen= (size_t)sizeof(struct tcpstat);
        }
@@ -4919,7 +5551,155 @@ tcp_getstat SYSCTL_HANDLER_ARGS
 
 }
 
-SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
+/*
+ * Checksum extended TCP header and data.
+ */
+int
+tcp_input_checksum(int af, struct mbuf *m, struct tcphdr *th, int off, int tlen)
+{
+       struct ifnet *ifp = m->m_pkthdr.rcvif;
+
+       switch (af) {
+       case AF_INET: {
+               struct ip *ip = mtod(m, struct ip *);
+               struct ipovly *ipov = (struct ipovly *)ip;
+
+               if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_DID_CSUM)
+                       return (0);
+
+               if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) ||
+                   (m->m_pkthdr.pkt_flags & PKTF_LOOP)) &&
+                   (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) {
+                       if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) {
+                               th->th_sum = m->m_pkthdr.csum_rx_val;
+                       } else {
+                               uint16_t sum = m->m_pkthdr.csum_rx_val;
+                               uint16_t start = m->m_pkthdr.csum_rx_start;
+
+                               /*
+                                * Perform 1's complement adjustment of octets
+                                * that got included/excluded in the hardware-
+                                * calculated checksum value.  Ignore cases
+                                * where the value includes or excludes the IP
+                                * header span, as the sum for those octets
+                                * would already be 0xffff and thus no-op.
+                                */
+                               if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) &&
+                                   start != 0 && (off - start) != off) {
+#if BYTE_ORDER != BIG_ENDIAN
+                                       if (start < off) {
+                                               HTONS(ip->ip_len);
+                                               HTONS(ip->ip_off);
+                                       }
+#endif
+                                       /* callee folds in sum */
+                                       sum = m_adj_sum16(m, start, off, sum);
+#if BYTE_ORDER != BIG_ENDIAN
+                                       if (start < off) {
+                                               NTOHS(ip->ip_off);
+                                               NTOHS(ip->ip_len);
+                                       }
+#endif
+                               }
+
+                               /* callee folds in sum */
+                               th->th_sum = in_pseudo(ip->ip_src.s_addr,
+                                   ip->ip_dst.s_addr,
+                                   sum + htonl(tlen + IPPROTO_TCP));
+                       }
+                       th->th_sum ^= 0xffff;
+               } else {
+                       uint16_t ip_sum;
+                       int len;
+                       char b[9];
+
+                       bcopy(ipov->ih_x1, b, sizeof (ipov->ih_x1));
+                       bzero(ipov->ih_x1, sizeof (ipov->ih_x1));
+                       ip_sum = ipov->ih_len;
+                       ipov->ih_len = (u_short)tlen;
+#if BYTE_ORDER != BIG_ENDIAN
+                       HTONS(ipov->ih_len);
+#endif
+                       len = sizeof (struct ip) + tlen;
+                       th->th_sum = in_cksum(m, len);
+                       bcopy(b, ipov->ih_x1, sizeof (ipov->ih_x1));
+                       ipov->ih_len = ip_sum;
+
+                       tcp_in_cksum_stats(len);
+               }
+               break;
+       }
+#if INET6
+       case AF_INET6: {
+               struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
+
+               if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_DID_CSUM)
+                       return (0);
+
+               if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) ||
+                   (m->m_pkthdr.pkt_flags & PKTF_LOOP)) &&
+                   (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) {
+                       if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) {
+                               th->th_sum = m->m_pkthdr.csum_rx_val;
+                       } else {
+                               uint16_t sum = m->m_pkthdr.csum_rx_val;
+                               uint16_t start = m->m_pkthdr.csum_rx_start;
+
+                               /*
+                                * Perform 1's complement adjustment of octets
+                                * that got included/excluded in the hardware-
+                                * calculated checksum value.
+                                */
+                               if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) &&
+                                   start != off) {
+                                       uint16_t s, d;
+
+                                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) {
+                                               s = ip6->ip6_src.s6_addr16[1];
+                                               ip6->ip6_src.s6_addr16[1] = 0 ;
+                                       }
+                                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) {
+                                               d = ip6->ip6_dst.s6_addr16[1];
+                                               ip6->ip6_dst.s6_addr16[1] = 0;
+                                       }
+
+                                       /* callee folds in sum */
+                                       sum = m_adj_sum16(m, start, off, sum);
+
+                                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
+                                               ip6->ip6_src.s6_addr16[1] = s;
+                                       if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
+                                               ip6->ip6_dst.s6_addr16[1] = d;
+                               }
+
+                               th->th_sum = in6_pseudo(
+                                   &ip6->ip6_src, &ip6->ip6_dst,
+                                   sum + htonl(tlen + IPPROTO_TCP));
+                       }
+                       th->th_sum ^= 0xffff;
+               } else {
+                       tcp_in6_cksum_stats(tlen);
+                       th->th_sum = in6_cksum(m, IPPROTO_TCP, off, tlen);
+               }
+               break;
+       }
+#endif /* INET6 */
+       default:
+               VERIFY(0);
+               /* NOTREACHED */
+       }
+
+       if (th->th_sum != 0) {
+               tcpstat.tcps_rcvbadsum++;
+               IF_TCP_STATINC(ifp, badformat);
+               return (-1);
+       }
+
+       return (0);
+}
+
+SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats,
+    CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0,
     tcp_getstat, "S,tcpstat", "TCP statistics (struct tcpstat, netinet/tcp_var.h)");
 
 static int