]> 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 302ab9431bb26343bbcb76f8af1466c45529c2ef..ab5242853b749bf90c5e8be48a8b954adb43f5a7 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2014 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
 #include <sys/socket.h>
 #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>
+
 #include <net/if.h>
 #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>
@@ -93,6 +98,7 @@
 #include <netinet/icmp_var.h>  /* for ICMP_BANDLIM     */
 #include <netinet/in_pcb.h>
 #include <netinet/ip_var.h>
+#include <mach/sdt.h>
 #if INET6
 #include <netinet/ip6.h>
 #include <netinet/icmp6.h>
 #include <netinet/tcp_seq.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>
 #endif
@@ -128,127 +137,208 @@ struct tcphdr tcp_savetcp;
 #endif /* CONFIG_MACF_NET || CONFIG_MACF_SOCKET */
 
 #include <sys/kdebug.h>
-
-#ifndef __APPLE__
-MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry");
-#endif
+#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
-
 struct tcpstat tcpstat;
 
 static int log_in_vain = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW | CTLFLAG_LOCKED,
     &log_in_vain, 0, "Log all incoming TCP connections");
 
 static int blackhole = 0;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW | CTLFLAG_LOCKED,
        &blackhole, 0, "Do not send RST when dropping refused connections");
 
 int tcp_delack_enabled = 3;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_delack_enabled, 0, 
     "Delay ACK to try and piggyback it onto a data packet");
 
 int tcp_lq_overflow = 1;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_lq_overflow, CTLFLAG_RW,
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_lq_overflow, CTLFLAG_RW | CTLFLAG_LOCKED,
     &tcp_lq_overflow, 0, 
     "Listen Queue Overflow");
 
+int tcp_recv_bg = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbg, CTLFLAG_RW | CTLFLAG_LOCKED,
+    &tcp_recv_bg, 0, 
+    "Receive background");
+
 #if TCP_DROP_SYNFIN
 static int drop_synfin = 1;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW | CTLFLAG_LOCKED,
     &drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
 #endif
 
 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,
-    &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,
-    &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,
+SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD | CTLFLAG_LOCKED,
     &tcp_reass_overflows, 0,
     "Global number of TCP Segment Reassembly Queue Overflows");
 
 
 __private_extern__ int slowlink_wsize = 8192;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowlink_wsize, CTLFLAG_RW,
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowlink_wsize, CTLFLAG_RW | CTLFLAG_LOCKED,
        &slowlink_wsize, 0, "Maximum advertised window size for slowlink");
 
-static int maxseg_unacked = 8;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, maxseg_unacked, CTLFLAG_RW,
+int maxseg_unacked = 8;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, maxseg_unacked, CTLFLAG_RW | CTLFLAG_LOCKED,
        &maxseg_unacked, 0, "Maximum number of outstanding segments left unacked");
 
-static int     tcp_do_rfc3465 = 1;
-SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW,
+int    tcp_do_rfc3465 = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW | CTLFLAG_LOCKED,
        &tcp_do_rfc3465, 0, "");
+
+int    tcp_do_rfc3465_lim2 = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465_lim2, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &tcp_do_rfc3465_lim2, 0, "Appropriate bytes counting w/ L=2*SMSS");
+
+int    rtt_samples_per_slot = 20;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, rtt_samples_per_slot, CTLFLAG_RW | CTLFLAG_LOCKED,
+       &rtt_samples_per_slot, 0, "Number of RTT samples stored for rtt history");
+
+int    tcp_allowed_iaj = ALLOWED_IAJ;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, recv_allowed_iaj, CTLFLAG_RW | CTLFLAG_LOCKED,
+        &tcp_allowed_iaj, 0, "Allowed inter-packet arrival jiter");
+
+int    tcp_acc_iaj_high_thresh = ACC_IAJ_HIGH_THRESH;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, acc_iaj_high_thresh, CTLFLAG_RW | CTLFLAG_LOCKED,
+        &tcp_acc_iaj_high_thresh, 0, "Used in calculating maximum accumulated IAJ");
+
+u_int32_t tcp_do_autorcvbuf = 1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, doautorcvbuf, CTLFLAG_RW | CTLFLAG_LOCKED,
+        &tcp_do_autorcvbuf, 0, "Enable automatic socket buffer tuning");
+
+u_int32_t tcp_autorcvbuf_inc_shift = 3;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, autorcvbufincshift, CTLFLAG_RW | CTLFLAG_LOCKED,
+        &tcp_autorcvbuf_inc_shift, 0, "Shift for increment in receive socket buffer size");
+
+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 = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, lro, CTLFLAG_RW | CTLFLAG_LOCKED,
+        &sw_lro, 0, "Used to coalesce TCP packets");
+
+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 = 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
+
 extern int tcp_TCPTV_MIN;
+extern int tcp_acc_iaj_high;
+extern int tcp_acc_iaj_react_limit;
+extern struct zone *tcp_reass_zone;
 
-u_long tcp_now;
+int tcprexmtthresh = 3;
+
+u_int32_t tcp_now;
+struct timeval tcp_uptime;     /* uptime when tcp_now was last updated */
+lck_spin_t *tcp_uptime_lock;   /* Used to sychronize updates to tcp_now */
 
 struct inpcbhead tcb;
 #define        tcb6    tcb  /* for KAME src sync over BSD*'s */
 struct inpcbinfo tcbinfo;
 
-static void     tcp_dooptions(struct tcpcb *,
-           u_char *, int, struct tcphdr *, struct tcpopt *);
+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 *);
-#if INET6
-static inline unsigned int tcp_maxmtu6(struct rtentry *);
-#endif
+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, int nlropkts, int lro_delay_factor);
+static void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj);
+#endif /* TRAFFIC_MGT */
 
-/* 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)
+static inline unsigned int tcp_maxmtu6(struct rtentry *);
 #endif
 
-extern u_long  *delack_bitmask;
+static void tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sb, 
+       struct tcpopt *to, u_int32_t tlen);
+
+void tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sb);
+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
 
-extern void    add_to_time_wait(struct tcpcb *);
-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;
-__private_extern__ int tcp_sockthreshold;
-__private_extern__ int tcp_win_scale;
 
 #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 ;            \
 }
@@ -256,52 +346,230 @@ __private_extern__ int tcp_win_scale;
 #define log_in_vain_log( a ) { log a; }
 #endif
 
+int tcp_rcvunackwin = TCPTV_UNACKWIN;
+int tcp_maxrcvidle = TCPTV_MAXRCVIDLE;
+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");
 
-/*
- * Indicate whether this ack should be delayed.  
- * We can delay the ack if:
- *  - delayed acks are enabled (set to 1) and
- *      - our last ack wasn't a 0-sized window.  We never want to delay
- *       the ack that opens up a 0-sized window.
- *  - delayed acks are enabled (set to 2, "more compatible") and
- *      - our last ack wasn't a 0-sized window.
- *      - if the peer hasn't sent us a TH_PUSH data packet (this solves 3649245)
- *      - the peer hasn't sent us a TH_PUSH data packet, if he did, take this as a clue that we
- *        need to ACK with no delay. This helps higher level protocols who won't send
- *        us more data even if the window is open because their last "segment" hasn't been ACKed
- *  - delayed acks are enabled (set to 3, "streaming detection") and
- *     - if we receive more than "maxseg_unacked"  full packets per second on this socket
- *             - if we don't have more than "maxseg_unacked" delayed so far
- *     - if those criteria aren't met, acts like "2". Allowing faster acking while browsing for example.
- *
- */
-#define DELAY_ACK(tp) \
-       (((tcp_delack_enabled == 1) && ((tp->t_flags & TF_RXWIN0SENT) == 0)) || \
-        (((tcp_delack_enabled == 2) && (tp->t_flags & TF_RXWIN0SENT) == 0) && \
-          ((thflags & TH_PUSH) == 0) && ((tp->t_flags & TF_DELACK) == 0)) || \
-        (((tcp_delack_enabled == 3) && (tp->t_flags & TF_RXWIN0SENT) == 0) && \
-          (tp->t_rcvtime == 0) && ((thflags & TH_PUSH) == 0) && \
-          (((tp->t_unacksegs == 0)) || \
-          ((tp->rcv_byps > (maxseg_unacked * tp->t_maxseg))  && (tp->t_unacksegs < maxseg_unacked)))))
+#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);
+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);
+static void tcp_bwmeas_check(struct tcpcb *tp);
+
+#if TRAFFIC_MGT
+void
+reset_acc_iaj(struct tcpcb *tp)
+{
+       tp->acc_iaj = 0;
+       tp->iaj_rwintop = 0;
+       CLEAR_IAJ_STATE(tp);
+}
+
+static inline void
+update_iaj_state(struct tcpcb *tp, uint32_t size, int rst_size)
+{
+       if (rst_size > 0)
+               tp->iaj_size = 0;
+       if (tp->iaj_size == 0 || size >= tp->iaj_size) {
+               tp->iaj_size = size;
+               tp->iaj_rcv_ts = tcp_now;
+               tp->iaj_small_pkt = 0;
+       }
+}
+
+/* For every 32 bit unsigned integer(v), this function will find the 
+ * largest integer n such that (n*n <= v). This takes at most 16 iterations 
+ * irrespective of the value of v and does not involve multiplications. 
+ */
+static inline int
+isqrt(unsigned int val) {
+       unsigned int sqrt_cache[11] = {0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100};
+       unsigned int temp, g=0, b=0x8000, bshft=15;
+       if ( val <= 100) {
+               for (g = 0; g <= 10; ++g) {
+                       if (sqrt_cache[g] > val) {
+                               g--;
+                               break;
+                       } else if (sqrt_cache[g] == val) {
+                               break;
+                       }
+               }
+       } else {
+               do {
+                       temp = (((g << 1) + b) << (bshft--));
+                       if (val >= temp) {
+                               g += b;
+                               val -= temp;
+                       }
+                       b >>= 1;
+               } while ( b > 0 && val > 0);
+       }
+       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, int nlropkts, int lro_delay_factor)
+{
+       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 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.
+        */
+       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.
+        */
+       if (tp->iaj_pktcnt > IAJ_IGNORE_PKTCNT) {
+               if ( cur_iaj <= allowed_iaj ) {
+                       if (tp->acc_iaj >= 2)
+                               acc_iaj = tp->acc_iaj - 2;
+                       else
+                               acc_iaj = 0;
+                               
+               } else {
+                       acc_iaj = tp->acc_iaj + (cur_iaj - allowed_iaj);
+               }
+
+               if (acc_iaj > MAX_ACC_IAJ)
+                       acc_iaj = MAX_ACC_IAJ;
+               tp->acc_iaj = acc_iaj;
+       }
+
+       /* 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 << 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. 
+        */
+       temp = tp->std_dev_iaj * tp->std_dev_iaj;
+       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);
+
+       return;
+}
+#endif /* TRAFFIC_MGT */
+
+/* Check if enough amount of data has been acknowledged since 
+ * bw measurement was started
+ */
+static void
+tcp_bwmeas_check(struct tcpcb *tp)
+{
+       int32_t bw_meas_bytes;
+       uint32_t bw, bytes, elapsed_time;
+       bw_meas_bytes = tp->snd_una - tp->t_bwmeas->bw_start;
+       if ((tp->t_flagsext & TF_BWMEAS_INPROGRESS) != 0 &&
+           bw_meas_bytes >= (int32_t)(tp->t_bwmeas->bw_size)) {
+               bytes = bw_meas_bytes;
+               elapsed_time = tcp_now - tp->t_bwmeas->bw_ts;
+               if (elapsed_time > 0) {
+                       bw = bytes / elapsed_time;
+                       if ( bw > 0) {
+                               if (tp->t_bwmeas->bw_sndbw > 0) {
+                                       tp->t_bwmeas->bw_sndbw = 
+                                           (((tp->t_bwmeas->bw_sndbw << 3) - tp->t_bwmeas->bw_sndbw) + bw) >> 3;
+                               } else {
+                                       tp->t_bwmeas->bw_sndbw = bw;
+                               }
+                       }
+               }
+               tp->t_flagsext &= ~(TF_BWMEAS_INPROGRESS);
+       }
+}
 
 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
@@ -309,6 +577,18 @@ 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. 
+        * Reset the stretch-ack algorithm at this point.
+        */
+       tcp_reset_stretch_ack(tp);
+
+#if TRAFFIC_MGT
+       if (tp->acc_iaj > 0)
+               reset_acc_iaj(tp);
+#endif /* TRAFFIC_MGT */       
 
        /*
         * Limit the number of segments in the reassembly queue to prevent
@@ -317,8 +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);
@@ -327,14 +609,13 @@ tcp_reass(tp, th, tlenp, m)
        }
 
        /* Allocate a new queue entry. If we can't, just drop the pkt. XXX */
-       MALLOC(te, struct tseg_qent *, sizeof (struct tseg_qent), M_TSEGQ,
-              M_NOWAIT);
+       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.
@@ -358,16 +639,27 @@ tcp_reass(tp, th, tlenp, m)
                        if (i >= *tlenp) {
                                tcpstat.tcps_rcvduppack++;
                                tcpstat.tcps_rcvdupbyte += *tlenp;
+                               if (nstat_collect) {
+                                       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);
-                               FREE(te, M_TSEGQ);
-                               tcp_reass_qsize--;
+                               zfree(tcp_reass_zone, te);
+                               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;
@@ -376,6 +668,13 @@ tcp_reass(tp, th, tlenp, m)
        }
        tcpstat.tcps_rcvoopack++;
        tcpstat.tcps_rcvoobyte += *tlenp;
+       if (nstat_collect) {
+               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;
+       }
 
        /*
         * While we overlap succeeding segments trim them or,
@@ -395,8 +694,8 @@ tcp_reass(tp, th, tlenp, m)
                nq = LIST_NEXT(q, tqe_q);
                LIST_REMOVE(q, tqe_q);
                m_freem(q->tqe_m);
-               FREE(q, M_TSEGQ);
-               tcp_reass_qsize--;
+               zfree(tcp_reass_zone, q);
+               tp->t_reassqlen--;
                q = nq;
        }
 
@@ -411,6 +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
@@ -419,47 +727,104 @@ present:
        if (!TCPS_HAVEESTABLISHED(tp->t_state))
                return (0);
        q = LIST_FIRST(&tp->t_segq);
-       if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
+       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(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 {
-                       if (sbappendstream(&so->so_rcv, q->tqe_m))
+               } else {
+                       so_recv_data_stat(so, q->tqe_m, 0); /* XXXX */
+                       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, 
+                                inp->inp_laddr, inp->inp_faddr,
+                                th->th_dport, th->th_sport);
+                       }
                }
-               FREE(q, M_TSEGQ);
-               tcp_reass_qsize--;
+               zfree(tcp_reass_zone, q);
+               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);
-
 }
 
 /*
@@ -469,22 +834,47 @@ static void
 tcp_reduce_congestion_window(
        struct tcpcb    *tp)
 {
-       u_int win;
-       
-       win = min(tp->snd_wnd, tp->snd_cwnd) /
-               2 / tp->t_maxseg;
-       if (win < 2)
-               win = 2;
-       tp->snd_ssthresh = win * tp->t_maxseg;
+       /*
+        * If the current tcp cc module has
+        * defined a hook for tasks to run
+        * before entering FR, call it
+        */
+       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_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
@@ -492,33 +882,605 @@ tcp_reduce_congestion_window(
  */
 #if INET6
 int
-tcp6_input(mp, offp)
-       struct mbuf **mp;
-       int *offp;
+tcp6_input(struct mbuf **mp, int *offp, int proto)
 {
+#pragma unused(proto)
        register struct mbuf *m = *mp;
-       struct in6_ifaddr *ia6;
+       uint32_t ia6_flags;
+       struct ifnet *ifp = m->m_pkthdr.rcvif;
+
+       IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE);
+
+       /* Expect 32-bit aligned data pointer on strict-align platforms */
+       MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
+
+       /*
+        * draft-itojun-ipv6-tcp-to-anycast
+        * better place to put this in?
+        */
+       if (ip6_getdstifaddr_info(m, NULL, &ia6_flags) == 0) {
+               if (ia6_flags & IN6_IFF_ANYCAST) {
+                       struct ip6_hdr *ip6;
+
+                       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_TCP_STATINC(ifp, icmp6unreach);
+
+                       return (IPPROTO_DONE);
+               }
+       }
+
+       tcp_input(m, *offp);
+       return (IPPROTO_DONE);
+}
+#endif
+
+/* Depending on the usage of mbuf space in the system, this function
+ * will return true or false. This is used to determine if a socket 
+ * buffer can take more memory from the system for auto-tuning or not.
+ */
+u_int8_t
+tcp_cansbgrow(struct sockbuf *sb)
+{
+       /* Calculate the host level space limit in terms of MSIZE buffers.
+        * We can use a maximum of half of the available mbuf space for
+        * socket buffers. 
+        */
+       u_int32_t mblim = ((nmbclusters >> 1) << (MCLSHIFT - MSIZESHIFT));
+
+       /* Calculate per sb limit in terms of bytes. We optimize this limit
+        * for upto 16 socket buffers.
+        */
+
+       u_int32_t sbspacelim = ((nmbclusters >> 4) << MCLSHIFT);
+
+       if ((total_sbmb_cnt < mblim) &&
+               (sb->sb_hiwat < sbspacelim)) {
+               return(1);
+       } else {
+               OSIncrementAtomic64(&sbmb_limreached);
+       }
+       return(0);
+}
+
+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);
+
+       /* The receive window scale negotiated at the 
+        * beginning of the connection will also set a 
+        * limit on the socket buffer size
+        */
+       newsize = min(newsize, TCP_MAXWIN << tp->rcv_scale);
+
+       /* Set new socket buffer size */
+       if (newsize > sbrcv->sb_hiwat &&
+               (sbreserve(sbrcv, newsize) == 1)) {
+               sbrcv->sb_idealsize = min(max(sbrcv->sb_idealsize, 
+                       (idealsize != 0) ? idealsize : newsize), 
+                       tcp_autorcvbuf_max);
+
+               /* Again check the limit set by the advertised 
+                * window scale 
+                */
+               sbrcv->sb_idealsize = min(sbrcv->sb_idealsize, 
+                       TCP_MAXWIN << tp->rcv_scale);
+       }
+}
+
+/* 
+ * This function is used to grow  a receive socket buffer. It
+ * will take into account system-level memory usage and the
+ * bandwidth available on the link to make a decision.
+ */
+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 ||
+               (tp->t_flagsext & TF_RECV_THROTTLE) ||
+               !LIST_EMPTY(&tp->t_segq)) {
+               /* Can not resize the socket buffer, just return */
+               goto out;
+       }
+
+       if (TSTMP_GT(tcp_now,
+               tp->rfbuf_ts + TCPTV_RCVBUFIDLE)) {
+               /* If there has been an idle period in the
+                * connection, just restart the measurement
+                */
+               goto out;
+       }
+
+       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.
+                */
+               if (TSTMP_GEQ(tcp_now, 
+                       tp->rfbuf_ts + TCPTV_RCVNOTS_QUANTUM)) {
+                       if (tp->rfbuf_cnt >= TCP_RCVNOTS_BYTELEVEL) {
+                               tcp_sbrcv_reserve(tp, sbrcv,
+                                       tcp_autorcvbuf_max, 0);
+                       }
+                       goto out;
+               } else {
+                       tp->rfbuf_cnt += pktlen;
+                       return;
+               }
+       } else if (to->to_tsecr != 0) {
+               /*
+                * If the timestamp shows that one RTT has
+                * completed, we can stop counting the
+                * bytes. Here we consider increasing
+                * 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 >> 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.
+                                *
+                                * Set the ideal size based on current
+                                * bandwidth measurements. We set the 
+                                * ideal size on receive socket buffer to
+                                * be twice the bandwidth delay product.
+                                */
+                               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));
+                       }
+                       goto out;
+               } else {
+                       tp->rfbuf_cnt += pktlen;
+                       return;
+               }
+       }
+out:
+       /* Restart the measurement */
+       tp->rfbuf_ts = 0;
+       tp->rfbuf_cnt = 0;
+       return;
+}
+
+/* This function will trim the excess space added to the socket buffer
+ * to help a slow-reading app. The ideal-size of a socket buffer depends
+ * on the link bandwidth or it is set by an application and we aim to 
+ * reach that size.
+ */
+void
+tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sbrcv) {
+       if (tcp_do_autorcvbuf == 1 && sbrcv->sb_idealsize > 0 &&
+               sbrcv->sb_hiwat > sbrcv->sb_idealsize) {
+               int32_t trim;
+               /* compute the difference between ideal and current sizes */
+               u_int32_t diff = sbrcv->sb_hiwat - sbrcv->sb_idealsize;
+
+               /* Compute the maximum advertised window for
+                * this connection.
+                */
+               u_int32_t advwin = tp->rcv_adv - tp->rcv_nxt;
+               
+               /* How much can we trim the receive socket buffer?
+                * 1. it can not be trimmed beyond the max rcv win advertised
+                * 2. if possible, leave 1/16 of bandwidth*delay to 
+                * avoid closing the win completely
+                */
+               u_int32_t leave = max(advwin, (sbrcv->sb_idealsize >> 4));
+
+               /* Sometimes leave can be zero, in that case leave at least
+                * a few segments worth of space.
+                */
+               if (leave == 0)
+                       leave = tp->t_maxseg << tcp_autorcvbuf_inc_shift;
+               
+               trim = sbrcv->sb_hiwat - (sbrcv->sb_cc + leave);
+               trim = imin(trim, (int32_t)diff);
+
+               if (trim > 0)
+                       sbreserve(sbrcv, (sbrcv->sb_hiwat - trim));
+       }
+}
+
+/* We may need to trim the send socket buffer size for two reasons:
+ * 1. if the rtt seen on the connection is climbing up, we do not
+ * want to fill the buffers any more.
+ * 2. if the congestion win on the socket backed off, there is no need
+ * to hold more mbufs for that connection than what the cwnd will allow.
+ */
+void
+tcp_sbsnd_trim(struct sockbuf *sbsnd) {
+       if (tcp_do_autosendbuf == 1 && 
+               ((sbsnd->sb_flags & (SB_AUTOSIZE | SB_TRIM)) == 
+                       (SB_AUTOSIZE | SB_TRIM)) &&
+               (sbsnd->sb_idealsize > 0) &&
+               (sbsnd->sb_hiwat > sbsnd->sb_idealsize)) {
+               u_int32_t trim = 0;
+               if (sbsnd->sb_cc <= sbsnd->sb_idealsize) {
+                       trim = sbsnd->sb_hiwat - sbsnd->sb_idealsize;
+               } else {
+                       trim = sbsnd->sb_hiwat - sbsnd->sb_cc;
+               }
+               sbreserve(sbsnd, (sbsnd->sb_hiwat - trim));
+       }
+       if (sbsnd->sb_hiwat <= sbsnd->sb_idealsize)
+               sbsnd->sb_flags &= ~(SB_TRIM);
+}
+
+/* 
+ * If timestamp option was not negotiated on this connection
+ * and this connection is on the receiving side of a stream
+ * then we can not measure the delay on the link accurately.
+ * Instead of enabling automatic receive socket buffer
+ * resizing, just give more space to the receive socket buffer.
+ */
+static inline void 
+tcp_sbrcv_tstmp_check(struct tcpcb *tp) {
+       struct socket *so = tp->t_inpcb->inp_socket;
+       u_int32_t newsize = 2 * tcp_recvspace;
+       struct sockbuf *sbrcv = &so->so_rcv;
+
+       if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP)) !=
+               (TF_REQ_TSTMP | TF_RCVD_TSTMP) &&
+               (sbrcv->sb_flags & SB_AUTOSIZE) != 0) {
+               tcp_sbrcv_reserve(tp, sbrcv, newsize, 0);
+       }
+}
+
+/* A receiver will evaluate the flow of packets on a connection 
+ * to see if it can reduce ack traffic. The receiver will start 
+ * stretching acks if all of the following conditions are met:
+ * 1. tcp_delack_enabled is set to 3
+ * 2. If the bytes received in the last 100ms is greater than a threshold
+ *      defined by maxseg_unacked
+ * 3. If the connection has not been idle for tcp_maxrcvidle period.
+ * 4. If the connection has seen enough packets to let the slow-start 
+ *      finish after connection establishment or after some packet loss.
+ *
+ * The receiver will stop stretching acks if there is congestion/reordering
+ * as indicated by packets on reassembly queue or an ECN. If the delayed-ack 
+ * timer fires while stretching acks, it means that the packet flow has gone 
+ * below the threshold defined by maxseg_unacked and the receiver will stop
+ * stretching acks. The receiver gets no indication when slow-start is completed 
+ * or when the connection reaches an idle state. That is why we use 
+ * 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->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) ||
+               (tp->rcv_waitforss >= tcp_rcvsspktcnt))) {
+               return(1);
+       }
+                
+       return(0);
+}
+
+/*
+ * 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.
+ */
+void
+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;
 
-       IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE);
+       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);   
+               }
 
-       /*
-        * draft-itojun-ipv6-tcp-to-anycast
-        * better place to put this in?
-        */
-       ia6 = ip6_getdstifaddr(m);
-       if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {                
-               struct ip6_hdr *ip6;
+               /*
+                * 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;
 
-               ip6 = mtod(m, struct ip6_hdr *);
-               icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
-                           (caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
-               return IPPROTO_DONE;
+                       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);
+                               }
+                       }
+               }
        }
 
-       tcp_input(m, *offp);
-       return IPPROTO_DONE;
+       /*
+        * 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;
 }
-#endif
 
 void
 tcp_input(m, off0)
@@ -527,11 +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;
@@ -542,9 +1503,8 @@ tcp_input(m, off0)
        struct in6_addr laddr6;
 #endif
        int dropsocket = 0;
-       int iss = 0;
-       int nosock = 0;
-       u_long tiwin;
+       int iss = 0, nosock = 0; 
+       u_int32_t tiwin, sack_bytes_acked = 0;
        struct tcpopt to;               /* options in this segment */
        struct sockaddr_in *next_hop = NULL;
 #if TCPDEBUG
@@ -552,23 +1512,49 @@ tcp_input(m, off0)
 #endif
        struct m_tag *fwd_tag;
        u_char ip_ecn = IPTOS_ECN_NOTECT;
+       unsigned int ifscope;
+       uint8_t isconnected, isdisconnected;
+       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 {                  \
+               stat += npkts;                          \
+} while (0)
+
+       TCP_INC_VAR(tcpstat.tcps_rcvtotal, nlropkts);
 
        /* Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. */
-       fwd_tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_IPFORWARD, NULL);
+       if (!SLIST_EMPTY(&m->m_pkthdr.tags)) {
+               fwd_tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID,
+                   KERNEL_TAG_TYPE_IPFORWARD, NULL);
+       } else {
+               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
@@ -576,20 +1562,21 @@ tcp_input(m, off0)
 #endif
        bzero((char *)&to, sizeof(to));
 
-       tcpstat.tcps_rcvtotal++;
-
-
-
 #if INET6
        if (isipv6) {
+               /* 
+                * 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() */
                ip6 = mtod(m, struct ip6_hdr *);
                tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0;
-               if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
-                       tcpstat.tcps_rcvbadsum++;
+               th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0);
+
+               if (tcp_input_checksum(AF_INET6, m, th, off0, tlen))
                        goto dropnosock;
-               }
-               th = (struct tcphdr *)((caddr_t)ip6 + off0);
 
                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])),
@@ -604,8 +1591,14 @@ tcp_input(m, off0)
                 */
                if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
                        /* XXX stat */
+                       IF_TCP_STATINC(ifp, unspecv6);
                        goto dropnosock;
                }
+               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;
        } else
 #endif /* INET6 */
        {
@@ -616,9 +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) {
@@ -626,72 +1616,30 @@ tcp_input(m, off0)
                        return;
                }
        }
-       ip = mtod(m, struct ip *);
-       ipov = (struct ipovly *)ip;
-       th = (struct tcphdr *)((caddr_t)ip + off0);
-       tlen = ip->ip_len;
 
-       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);
+       /* Expect 32-bit aligned data pointer on strict-align platforms */
+       MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
 
-       if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
-               if (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16) {
-                       u_short pseudo;
-                       char b[9];
-                       *(uint32_t*)&b[0] = *(uint32_t*)&ipov->ih_x1[0];
-                       *(uint32_t*)&b[4] = *(uint32_t*)&ipov->ih_x1[4];
-                       *(uint8_t*)&b[8] = *(uint8_t*)&ipov->ih_x1[8];
-                       
-                       bzero(ipov->ih_x1, sizeof(ipov->ih_x1));
-                       ipov->ih_len = (u_short)tlen;
-                       HTONS(ipov->ih_len);
-                       pseudo = in_cksum(m, sizeof (struct ip));
-                       
-                       *(uint32_t*)&ipov->ih_x1[0] = *(uint32_t*)&b[0];
-                       *(uint32_t*)&ipov->ih_x1[4] = *(uint32_t*)&b[4];
-                       *(uint8_t*)&ipov->ih_x1[8] = *(uint8_t*)&b[8];
-                       
-                       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.
-                */
-               *(uint32_t*)&b[0] = *(uint32_t*)&ipov->ih_x1[0];
-               *(uint32_t*)&b[4] = *(uint32_t*)&ipov->ih_x1[4];
-               *(uint8_t*)&b[8] = *(uint8_t*)&ipov->ih_x1[8];
-               
-               len = sizeof (struct ip) + tlen;
-               bzero(ipov->ih_x1, sizeof(ipov->ih_x1));
-               ipov->ih_len = (u_short)tlen;
-               HTONS(ipov->ih_len);
-               th->th_sum = in_cksum(m, len);
-               
-               *(uint32_t*)&ipov->ih_x1[0] = *(uint32_t*)&b[0];
-               *(uint32_t*)&ipov->ih_x1[4] = *(uint32_t*)&b[4];
-               *(uint8_t*)&ipov->ih_x1[8] = *(uint8_t*)&b[8];
+       ip = mtod(m, struct ip *);
+       th = (struct tcphdr *)(void *)((caddr_t)ip + off0);
+       tlen = ip->ip_len;
 
-               tcp_in_cksum_stats(len);
-       }
-       if (th->th_sum) {
-               tcpstat.tcps_rcvbadsum++;
+       if (tcp_input_checksum(AF_INET, m, th, off0, tlen))
                goto dropnosock;
-       }
+
 #if INET6
        /* Re-initialization for later version check */
        ip->ip_v = IPVERSION;
 #endif
        ip_ecn = (ip->ip_tos & IPTOS_ECN_MASK);
+
+       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);
+
        }
 
        /*
@@ -701,6 +1649,7 @@ tcp_input(m, off0)
        off = th->th_off << 2;
        if (off < sizeof (struct tcphdr) || off > tlen) {
                tcpstat.tcps_rcvbadoff++;
+               IF_TCP_STATINC(ifp, badformat);
                goto dropnosock;
        }
        tlen -= off;    /* tlen is used instead of ti->ti_len */
@@ -709,7 +1658,7 @@ tcp_input(m, off0)
                if (isipv6) {
                        IP6_EXTHDR_CHECK(m, off0, off, return);
                        ip6 = mtod(m, struct ip6_hdr *);
-                       th = (struct tcphdr *)((caddr_t)ip6 + off0);
+                       th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0);
                } else
 #endif /* INET6 */
                {
@@ -719,8 +1668,7 @@ tcp_input(m, off0)
                                        return;
                                }
                                ip = mtod(m, struct ip *);
-                               ipov = (struct ipovly *)ip;
-                               th = (struct tcphdr *)((caddr_t)ip + off0);
+                               th = (struct tcphdr *)(void *)((caddr_t)ip + off0);
                        }
                }
                optlen = off - sizeof (struct tcphdr);
@@ -735,11 +1683,11 @@ tcp_input(m, off0)
                if ((optlen == TCPOLEN_TSTAMP_APPA ||
                        (optlen > TCPOLEN_TSTAMP_APPA &&
                        optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
-                       *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
+                       *(u_int32_t *)(void *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
                        (th->th_flags & TH_SYN) == 0) {
                        to.to_flags |= TOF_TS;
-                       to.to_tsval = ntohl(*(u_int32_t *)(optp + 4));
-                       to.to_tsecr = ntohl(*(u_int32_t *)(optp + 8));
+                       to.to_tsval = ntohl(*(u_int32_t *)(void *)(optp + 4));
+                       to.to_tsecr = ntohl(*(u_int32_t *)(void *)(optp + 8));
                        optp = NULL;    /* we've parsed the options */
                }
        }
@@ -753,18 +1701,12 @@ tcp_input(m, off0)
         *
         * This is a violation of the TCP specification.
         */
-       if (drop_synfin && (thflags & (TH_SYN|TH_FIN)) == (TH_SYN|TH_FIN))
+       if (drop_synfin && (thflags & (TH_SYN|TH_FIN)) == (TH_SYN|TH_FIN)) {
+               IF_TCP_STATINC(ifp, synfin);
                goto dropnosock;
+       }
 #endif
 
-       /*
-        * Convert TCP protocol specific fields to host format.
-        */
-       NTOHL(th->th_seq);
-       NTOHL(th->th_ack);
-       NTOHS(th->th_win);
-       NTOHS(th->th_urp);
-
        /*
         * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
         * until after ip6_savecontrol() is called and before other functions
@@ -774,11 +1716,43 @@ tcp_input(m, off0)
         * parameters to be unchanged.
         */
        drop_hdrlen = off0 + off;
+       
+       /* Since this is an entry point for input processing of tcp packets, we
+        * can update the tcp clock here.
+        */
+       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_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.
+        */
+
+#if BYTE_ORDER != BIG_ENDIAN
+       NTOHL(th->th_seq);
+       NTOHL(th->th_ack);
+       NTOHS(th->th_win);
+       NTOHS(th->th_urp);
+#endif
 
        /*
         * Locate pcb for segment.
         */
 findpcb:
+
+       isconnected = FALSE;
+       isdisconnected = FALSE;
+
 #if IPFIREWALL_FORWARD
        if (next_hop != NULL
 #if INET6
@@ -821,22 +1795,32 @@ findpcb:
            ip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif);
       }
 
-#if IPSEC
-       if (ipsec_bypass == 0)  {
+       /*
+        * Use the interface scope information from the PCB for outbound
+        * segments.  If the PCB isn't present and if scoped routing is
+        * enabled, tcp_respond will use the scope of the interface where
+        * the segment arrived on.
+        */
+       if (inp != NULL && (inp->inp_flags & INP_BOUND_IF))
+               ifscope = inp->inp_boundifp->if_index;
+#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);
-                               goto dropnosock;
-                       }
-               } else
-#endif /* INET6 */
-                       if (inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) {
-                         IPSEC_STAT_INCREMENT(ipsecstat.in_polvio);
-                               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
@@ -878,7 +1862,8 @@ findpcb:
                                        ntohs(th->th_sport), thflags);
                                break;
                        case 3:
-                               if ((thflags & TH_SYN) &&
+                       case 4:
+                               if ((thflags & TH_SYN) && !(thflags & TH_ACK) &&
                                        !(m->m_flags & (M_BCAST | M_MCAST)) &&
 #if INET6
                                        ((isipv6 && !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) ||
@@ -899,6 +1884,7 @@ findpcb:
                }
                if (blackhole) { 
                        if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type != IFT_LOOP)
+                               
                                switch (blackhole) {
                                case 1:
                                        if (thflags & TH_SYN)
@@ -911,30 +1897,26 @@ findpcb:
                                }
                }
                rstreason = BANDLIM_RST_CLOSEDPORT;
+               IF_TCP_STATINC(ifp, noconnnolist);
                goto dropwithresetnosock;
        }
        so = inp->inp_socket;
        if (so == NULL) {
-               if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) 
-                       inp = NULL;     // pretend we didn't find it 
+               /* This case shouldn't happen  as the socket shouldn't be null
+                * if inp_state isn't set to INPCB_STATE_DEAD
+                * But just in case, we pretend we didn't find the socket if we hit this case
+                * as this isn't cause for a panic (the socket might be leaked however)...
+                */
+               inp = NULL;
 #if TEMPDEBUG
-               printf("tcp_input: no more socket for inp=%x\n", inp);
+               printf("tcp_input: no more socket for inp=%x. This shouldn't happen\n", inp);
 #endif
                goto dropnosock;
        }
 
-#ifdef __APPLE__
-        /* 
-         * Bogus state when listening port owned by SharedIP with loopback as the 
-         * only configured interface: BlueBox does not filters loopback
-         */ 
-       if (so == &tcbinfo.nat_dummy_socket)
-               goto drop;
-
-#endif
-       tcp_lock(so, 1, 2);
+       tcp_lock(so, 1, 0);
        if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) {
-               tcp_unlock(so, 1, 2);
+               tcp_unlock(so, 1, (void *)2);
                inp = NULL;     // pretend we didn't find it 
                goto dropnosock;
        }
@@ -942,6 +1924,7 @@ findpcb:
        tp = intotcpcb(inp);
        if (tp == 0) {
                rstreason = BANDLIM_RST_CLOSEDPORT;
+               IF_TCP_STATINC(ifp, noconnlist);
                goto dropwithreset;
        }
        if (tp->t_state == TCPS_CLOSED)
@@ -958,6 +1941,11 @@ findpcb:
                goto drop;
 #endif
 
+       /* 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)) {
 #if TCPDEBUG
                if (so->so_options & SO_DEBUG) {
@@ -980,28 +1968,79 @@ findpcb:
 #if INET6
                        struct inpcb *oinp = sotoinpcb(so);
 #endif /* INET6 */
-                       int ogencnt = so->so_gencnt;
+                       struct ifnet *head_ifscope;
+                       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_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 !IPSEC
                        /*
-                        * Current IPsec implementation makes incorrect IPsec
-                        * cache if this check is done here.
-                        * So delay this until duplicated socket is created.
+                        * If the state is LISTEN then ignore segment if it contains an RST.
+                        * If the segment contains an ACK then it is bad and send a RST.
+                        * If it does not contain a SYN then it is not interesting; drop it.
+                        * If it is from this socket, drop it, it must be forged.
                         */
                        if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) {
-                               /*
-                                * Note: dropwithreset makes sure we don't
-                                * send a RST in response to a RST.
-                                */
+                               IF_TCP_STATINC(ifp, listbadsyn);
+
+                               if (thflags & TH_RST) {
+                                       goto drop;
+                               }
                                if (thflags & TH_ACK) {
+                                       tp = NULL;
                                        tcpstat.tcps_badsyn++;
                                        rstreason = BANDLIM_RST_OPENPORT;
                                        goto dropwithreset;
                                }
+
+                               /* We come here if there is no SYN set */
+                               tcpstat.tcps_badsyn++;
                                goto drop;
                        }
-#endif
                        KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_START,0,0,0,0,0);
+                       if (th->th_dport == th->th_sport) {
+#if INET6
+                               if (isipv6) {
+                                       if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
+                                                       &ip6->ip6_src))
+                                               goto drop;
+                               } else
+#endif /* INET6 */
+                                       if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
+                                               goto drop;
+                       }
+                       /*
+                        * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
+                        * in_broadcast() should never return true on a received
+                        * packet with M_BCAST not set.
+                        *
+                        * Packets with a multicast source address should also
+                        * be discarded.
+                        */
+                       if (m->m_flags & (M_BCAST|M_MCAST))
+                               goto drop;
+#if INET6
+                       if (isipv6) {
+                               if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
+                                       IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
+                                       goto drop;
+                       } else
+#endif
+                       if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
+                               IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
+                               ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
+                               in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
+                               goto drop;
+
 
 #if INET6
                        /*
@@ -1016,32 +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;
-
-                               if ((ia6 = ip6_getdstifaddr(m)) &&
-                                   (ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
-                                       tp = NULL;
-                                       rstreason = BANDLIM_RST_OPENPORT;
-                                       goto dropwithreset;
+                               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_TCP_STATINC(ifp, deprecate6);
+                                               goto dropwithreset;
+                                       }
                                }
                        }
 #endif
@@ -1082,12 +2109,10 @@ findpcb:
                                if (!so2) 
                                        goto drop;
                        }
-                       /*
-                        * Make sure listening socket did not get closed during socket allocation,
-                        * not only this is incorrect but it is know to cause panic
-                        */
-                       if (so->so_gencnt != ogencnt)
-                               goto drop;
+
+                       /* Point "inp" and "tp" in tandem to new socket */
+                       inp = (struct inpcb *)so2->so_pcb;
+                       tp = intotcpcb(inp);
 
                        oso = so;
                        tcp_unlock(so, 0, 0); /* Unlock but keep a reference on listener for now */
@@ -1095,8 +2120,6 @@ findpcb:
                        so = so2;
                        tcp_lock(so, 1, 0);
                        /*
-                        * This is ugly, but ....
-                        *
                         * Mark socket as temporary until we're
                         * committed to keeping it.  The code at
                         * ``drop'' and ``dropwithreset'' check the
@@ -1104,9 +2127,38 @@ findpcb:
                         * socket created here should be discarded.
                         * We mark the socket as discardable until
                         * we're committed to it below in TCPS_LISTEN.
+                        * There are some error conditions in which we
+                        * have to drop the temporary socket.
                         */
                        dropsocket++;
-                       inp = (struct inpcb *)so->so_pcb;
+                       /*
+                        * Inherit INP_BOUND_IF from listener; testing if
+                        * head_ifscope is non-NULL is sufficient, since it
+                        * can only be set to a non-zero value earlier if
+                        * the listener has such a flag set.
+                        */
+                       if (head_ifscope != NULL) {
+                               inp->inp_flags |= INP_BOUND_IF;
+                               inp->inp_boundifp = head_ifscope;
+                       } else {
+                               inp->inp_flags &= ~INP_BOUND_IF;
+                       }
+                       /*
+                        * Inherit restrictions from listener.
+                        */
+                       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.
+                        */
+                       if (head_recvanyif)
+                               inp->inp_flags |= INP_RECV_ANYIF;
+                       else
+                               inp->inp_flags &= ~INP_RECV_ANYIF;
 #if INET6
                        if (isipv6)
                                inp->in6p_laddr = ip6->ip6_dst;
@@ -1114,7 +2166,7 @@ findpcb:
                                inp->inp_vflag &= ~INP_IPV6;
                                inp->inp_vflag |= INP_IPV4;
 #endif /* INET6 */
-                       inp->inp_laddr = ip->ip_dst;
+                               inp->inp_laddr = ip->ip_dst;
 #if INET6
                        }
 #endif /* INET6 */
@@ -1129,36 +2181,12 @@ findpcb:
                                        inp->in6p_laddr = in6addr_any;
                                else
 #endif /* INET6 */
-                               inp->inp_laddr.s_addr = INADDR_ANY;
+                                       inp->inp_laddr.s_addr = INADDR_ANY;
                                inp->inp_lport = 0;
                                tcp_lock(oso, 0, 0);    /* release ref on parent */
                                tcp_unlock(oso, 1, 0);
                                goto drop;
                        }
-#if IPSEC
-                       /*
-                        * To avoid creating incorrectly cached IPsec
-                        * association, this is need to be done here.
-                        *
-                        * Subject: (KAME-snap 748)
-                        * From: Wayne Knowles <w.knowles@niwa.cri.nz>
-                        * ftp://ftp.kame.net/pub/mail-list/snap-users/748
-                        */
-                       if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) {
-                               /*
-                                * Note: dropwithreset makes sure we don't
-                                * send a RST in response to a RST.
-                                */
-                               tcp_lock(oso, 0, 0);    /* release ref on parent */
-                               tcp_unlock(oso, 1, 0);
-                               if (thflags & TH_ACK) {
-                                       tcpstat.tcps_badsyn++;
-                                       rstreason = BANDLIM_RST_OPENPORT;
-                                       goto dropwithreset;
-                               }
-                               goto drop;
-                       }
-#endif
 #if INET6
                        if (isipv6) {
                                /*
@@ -1182,7 +2210,7 @@ findpcb:
                                                                M_NOWAIT);
                        } else
 #endif /* INET6 */
-                       inp->inp_options = ip_srcroute();
+                               inp->inp_options = ip_srcroute();
                        tcp_lock(oso, 0, 0);
 #if IPSEC
                        /* copy old policy into new socket's */
@@ -1196,178 +2224,226 @@ findpcb:
                                        printf("tcp_input: could not copy policy\n");
                        }
 #endif
-                       tcp_unlock(oso, 1, 0);  /* now drop the reference on the listener */
-                       tp = intotcpcb(inp);
+                       /* inherit states from the listener */
+                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                               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|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;
-                       /* Compute proper scaling value from buffer space */
-                       if (inp->inp_pcbinfo->ipi_count < tcp_sockthreshold) {
-                               tp->request_r_scale = max(tcp_win_scale, tp->request_r_scale);
-                               so->so_rcv.sb_hiwat = lmin(TCP_MAXWIN << tp->request_r_scale, (sb_max / (MSIZE+MCLBYTES)) * MCLBYTES);  
-                       }
-                       else {
-                               while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
-                               TCP_MAXWIN << tp->request_r_scale <
-                               so->so_rcv.sb_hiwat)
-                                       tp->request_r_scale++;
-                       }
+                       if ((so->so_flags & SOF_NOTSENT_LOWAT) != 0)
+                               tp->t_notsent_lowat = tp0->t_notsent_lowat;
+
+                       /* now drop the reference on the listener */
+                       tcp_unlock(oso, 1, 0);
+
+                       tcp_set_max_rwinscale(tp, so);
 
                        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);
 
-#if 1
-       lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-#endif
-       /*
-        * 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.
-        *
-        * The packet per second count is done all the time and is also used
-        * by "DELAY_ACK" to detect streaming situations.
-        *
-        */
        if (tp->t_state == TCPS_ESTABLISHED && tlen > 0) {
-               if (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. 
+               /* 
+                * 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.
                 */
-                       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. %lubyte/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;
-                               }
-                       }
+               if ((tp->t_flagsext & TF_RCVUNACK_WAITSS) != 0) {
+                       TCP_INC_VAR(tp->rcv_waitforss, nlropkts);
+               }
+               if (tcp_stretch_ack_enable(tp)) {
+                       tp->t_flags |= TF_STRETCHACK;
+                       tp->t_flagsext &= ~(TF_RCVUNACK_WAITSS);
+                       tp->rcv_waitforss = 0;
                } else {
-                       tp->rcv_reset = tcp_now + TCP_RETRANSHZ;
-                       tp->rcv_pps = 1;
-                       tp->rcv_byps = tlen + off;
+                       tp->t_flags &= ~(TF_STRETCHACK);
+               }
+               if (TSTMP_GT(tp->rcv_unackwin, tcp_now)) {
+                       tp->rcv_by_unackwin += (tlen + off);
+               } else {
+                       tp->rcv_unackwin = tcp_now + tcp_rcvunackwin;
+                       tp->rcv_by_unackwin = tlen + off;
                }
        }
-       
-#if TRAFFIC_MGT
-       if (so->so_traffic_mgt_flags & TRAFFIC_MGT_SO_BACKGROUND) {
-               tcpstat.tcps_bg_rcvtotal++;
-
-                /* Take snapshots of pkts recv;
-                 * tcpcb should have been initialized to 0 when allocated, 
-                 * so if 0 then this is the first time we're doing this
-                 */
-               if (!tp->tot_recv_snapshot) {
-                        tp->tot_recv_snapshot = tcpstat.tcps_rcvtotal;
-                }
-               if (!tp->bg_recv_snapshot) {
-                        tp->bg_recv_snapshot = tcpstat.tcps_bg_rcvtotal;
-                }
-       }
-#endif /* TRAFFIC_MGT */
 
+       /* 
+        * Keep track of how many bytes were received in the LRO packet
+        */
+       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_SETUPSENT | TE_SETUPRECEIVED)) ==
-                (TE_SETUPSENT | TE_SETUPRECEIVED) && tlen > 0 &&
+               ((tp->ecn_flags & (TE_ECN_ON)) == (TE_ECN_ON)) && tlen > 0 &&
                SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
                SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
                tp->ecn_flags |= TE_SENDECE;
        }
        
        /*
-          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 
+        * ip tos ecn bits or by the CWR bit in TCP header flags, reset
+        * 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->ecn_flags & TE_SETUPSENT)
+           && (ip_ecn == IPTOS_ECN_CE || (thflags & TH_CWR)))
+               tcp_reset_stretch_ack(tp);
+
+       /* 
+        * Try to determine if we are receiving a packet after a long time.
+        * Use our own approximation of idletime to roughly measure remote 
+        * end's idle time. Since slowstart is used after an idle period
+        * we want to avoid doing LRO if the remote end is not up to date
+        * on initial window support and starts with 1 or 2 packets as its IW.
+        */
+        if (sw_lro && (tp->t_flagsext & TF_LRO_OFFLOADED) &&
+               ((tcp_now - tp->t_rcvtime) >= (TCP_IDLETIMEOUT(tp)))) {
+               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 = 0;
        if (TCPS_HAVEESTABLISHED(tp->t_state))
-               tp->t_timer[TCPT_KEEP] = 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)
-               tcp_dooptions(tp, optp, optlen, th, &to);
-
-       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 (tp->t_state != TCPS_LISTEN && optp) {
+               tcp_dooptions(tp, optp, optlen, th, &to, ifscope);
+#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;
                        tp->ts_recent_age = tcp_now;
                }
                if (to.to_flags & TOF_MSS)
-                       tcp_mss(tp, to.to_mss);
-               if (tp->sack_enable) {
+                       tcp_mss(tp, to.to_mss, ifscope);
+               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;
                }
        }
 
+#if TRAFFIC_MGT
+       /* Compute inter-packet arrival jitter. According to RFC 3550, inter-packet 
+        * arrival jitter is defined as the difference in packet spacing at the 
+        * receiver compared to the sender for a pair of packets. When two packets 
+        * of maximum segment size come one after the other with consecutive 
+        * sequence numbers, we consider them as packets sent together at the 
+        * sender and use them as a pair to compute inter-packet arrival jitter.
+        * This metric indicates the delay induced by the network components due
+        * to queuing in edge/access routers.
+        */
+       if (tp->t_state == TCPS_ESTABLISHED &&
+           (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK|TH_ECE|TH_PUSH)) == TH_ACK &&
+           ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) &&
+           ((to.to_flags & TOF_TS) == 0 ||
+            TSTMP_GEQ(to.to_tsval, tp->ts_recent)) &&
+           th->th_seq == tp->rcv_nxt &&
+           LIST_EMPTY(&tp->t_segq)) {
+               int seg_size = tlen;
+               if (tp->iaj_pktcnt <= IAJ_IGNORE_PKTCNT) {
+                       TCP_INC_VAR(tp->iaj_pktcnt, nlropkts);
+               }
+
+               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 ||
+                       (seg_size == tp->iaj_size && tp->iaj_rcv_ts == 0)) {
+                       /* State related to inter-arrival jitter is uninitialized 
+                        * or we are trying to find a good first packet to start 
+                        * computing the metric
+                        */
+                       update_iaj_state(tp, seg_size, 0);
+               } else {
+                       if (seg_size == tp->iaj_size) {
+                               /* Compute inter-arrival jitter taking this packet 
+                                * as the second packet
+                                */
+                               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.
+                                * Some times the maximum size supported on a path can 
+                                * change if there is a new link with smaller MTU. 
+                                * The receiver will not know about this change. 
+                                * If there are too many packets smaller than iaj_size, 
+                                * we try to learn the iaj_size again.
+                                */
+                               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 {
+                                       CLEAR_IAJ_STATE(tp);
+                               }
+                       } else {
+                               update_iaj_state(tp, seg_size, 0);
+                       }
+               }
+       } else {
+               CLEAR_IAJ_STATE(tp);
+       }
+#endif /* TRAFFIC_MGT */
+
        /*
         * Header prediction: check for the two common cases
         * of a uni-directional data xfer.  If the packet has
@@ -1406,75 +2482,65 @@ findpcb:
                        tp->ts_recent = to.to_tsval;
                }
 
+               /* Force acknowledgment if we received a FIN */
+
+               if (thflags & TH_FIN)
+                       tp->t_flags |= TF_ACKNOW;
+
                if (tlen == 0) {
                        if (SEQ_GT(th->th_ack, tp->snd_una) &&
                            SEQ_LEQ(th->th_ack, tp->snd_max) &&
                            tp->snd_cwnd >= tp->snd_ssthresh &&
-                           ((!tcp_do_newreno && !tp->sack_enable &&
-                             tp->t_dupacks < tcprexmtthresh) ||
-                            ((tcp_do_newreno || tp->sack_enable) &&
-                             !IN_FASTRECOVERY(tp) && to.to_nsacks == 0 &&
-                             TAILQ_EMPTY(&tp->snd_holes)))) {
+                           (!IN_FASTRECOVERY(tp) && 
+                           ((!(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 &&
-                                   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;
-                               }
-                               /*
-                                * 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)) { /* Makes sure we already have a TS */
-                                       if (!tp->t_rttlow ||
-                                           tp->t_rttlow > tcp_now - to.to_tsecr)
-                                               tp->t_rttlow = 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)) {
-                                       if (!tp->t_rttlow ||
-                                           tp->t_rttlow > tcp_now - tp->t_rtttime)
-                                               tp->t_rttlow = tcp_now - tp->t_rtttime;
-                                       tcp_xmit_timer(tp, tp->t_rtttime);
-                               }
-                               acked = th->th_ack - tp->snd_una;
+                               ++tcpstat.tcps_predack;
+
+                               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;
-                               /*
-                                * Grow the congestion window, if the
-                                * connection is cwnd bound.
+                               
+                               /* Handle an ack that is in sequence during congestion
+                                * avoidance phase. The calculations in this function 
+                                * assume that snd_una is not updated yet. 
                                 */
+                               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) &&
                                    SEQ_LEQ(th->th_ack, tp->snd_recover))
                                        tp->snd_recover = th->th_ack - 1;
                                tp->snd_una = th->th_ack;
+
                                /*
                                 * pull snd_wl2 up to prevent seq wrap relative
                                 * 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
@@ -1485,16 +2551,24 @@ 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] = 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)
+                                       tcp_bwmeas_check(tp);
                                sowwakeup(so); /* has to be done with socket lock held */
                                if ((so->so_snd.sb_cc) || (tp->t_flags & TF_ACKNOW)) {
-                                       tp->t_unacksegs = 0;
                                        (void) tcp_output(tp);
                                }
+
+                               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;
@@ -1507,8 +2581,33 @@ findpcb:
                         * with nothing on the reassembly queue and
                         * we have enough buffer space to take it.
                         */
+
+                       /*
+                        * If this is a connection in steady state, start
+                        * coalescing packets belonging to this flow.
+                        */
+                       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_flagsext &= ~TF_LRO_OFFLOADED;
+                               tp->t_idleat = tp->rcv_nxt;
+                       } 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_idleat == 0) || ((th->th_seq - 
+                            tp->t_idleat) > (tp->t_maxseg << lro_start)))) {
+                               tp->t_flagsext |= TF_LRO_OFFLOADED;
+                               tcp_start_coalescing(ip, th, tlen);
+                               tp->t_idleat = 0;
+                       }
+
                        /* 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;
@@ -1522,15 +2621,46 @@ findpcb:
                         * rcv_nxt.
                         */
                        tp->rcv_up = tp->rcv_nxt;
-                       tcpstat.tcps_rcvpack++;
+                       TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts);
                        tcpstat.tcps_rcvbyte += tlen;
-                       ND6_HINT(tp);   /* some progress has been done */
+                       if (nstat_collect) {
+                               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);
+                               }
+                               INP_ADD_STAT(inp, cell, wifi, wired,rxbytes,
+                                   tlen);
+                       }
+
+                       /*
+                        * 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);
+                       
                        /*
                         * Add data to socket buffer.
                         */
+                       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),
@@ -1544,14 +2674,20 @@ findpcb:
                                        (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)),
                                        th->th_seq, th->th_ack, th->th_win); 
                        }
-                       if (DELAY_ACK(tp))  {
-                               tp->t_flags |= TF_DELACK;
-                               tp->t_unacksegs++;
+                       TCP_INC_VAR(tp->t_unacksegs, nlropkts);
+                       if (DELAY_ACK(tp, th))  {
+                               if ((tp->t_flags & TF_DELACK) == 0) {
+                                       tp->t_flags |= TF_DELACK;
+                                       tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack);
+                               }
                        } else {
-                               tp->t_unacksegs = 0;
                                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);
                        return;
@@ -1564,13 +2700,9 @@ findpcb:
         * Receive window is amount of space in rcv queue,
         * but not less than advertised window.
         */
-#if 1
-       lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-#endif
-       { 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 */
@@ -1578,17 +2710,26 @@ 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) {
 
        /*
-        * If the state is LISTEN then ignore segment if it contains an RST.
-        * If the segment contains an ACK then it is bad and send a RST.
-        * If it does not contain a SYN then it is not interesting; drop it.
-        * If it is from this socket, drop it, it must be forged.
-        * Don't bother responding if the destination was a broadcast.
-        * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
+        * Initialize tp->rcv_nxt, and tp->irs, select an initial
         * tp->iss, and send a segment:
         *     <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
         * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
@@ -1602,50 +2743,8 @@ findpcb:
                register struct sockaddr_in6 *sin6;
 #endif
 
-#if 1
-               lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-#endif
-               if (thflags & TH_RST) 
-                       goto drop;
-               if (thflags & TH_ACK) {
-                       rstreason = BANDLIM_RST_OPENPORT;
-                       goto dropwithreset;
-               }
-               if ((thflags & TH_SYN) == 0)
-                       goto drop;
-               if (th->th_dport == th->th_sport) {
-#if INET6
-                       if (isipv6) {
-                               if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
-                                                      &ip6->ip6_src))
-                                       goto drop;
-                       } else
-#endif /* INET6 */
-                       if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
-                               goto drop;
-               }
-               /*
-                * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
-                * in_broadcast() should never return true on a received
-                * packet with M_BCAST not set.
-                *
-                * Packets with a multicast source address should also
-                * be discarded.
-                */
-               if (m->m_flags & (M_BCAST|M_MCAST))
-                       goto drop;
-#if INET6
-               if (isipv6) {
-                       if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
-                           IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
-                               goto drop;
-               } else
-#endif
-               if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
-                   IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
-                   ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
-                   in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
-                       goto drop;
+               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,
@@ -1670,9 +2769,7 @@ findpcb:
                } else
 #endif
            {
-#if 0
-                       lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-#endif
+                       lck_mtx_assert(&((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
                        MALLOC(sin, struct sockaddr_in *, sizeof *sin, M_SONAME,
                       M_NOWAIT);
                        if (sin == NULL)
@@ -1685,7 +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)) {
+                       if (in_pcbconnect(inp, (struct sockaddr *)sin, proc0,
+                           IFSCOPE_NONE, NULL)) {
                                inp->inp_laddr = laddr;
                                FREE(sin, M_SONAME);
                                goto drop;
@@ -1693,11 +2791,11 @@ findpcb:
                        FREE(sin, M_SONAME);
                }
 
-               tcp_dooptions(tp, optp, optlen, th, &to);
+               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;
                }
@@ -1719,14 +2817,40 @@ findpcb:
                tp->snd_wnd = tiwin;    /* initial send-window */
                tp->t_flags |= TF_ACKNOW;
                tp->t_unacksegs = 0;
+               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                       struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED);
                tp->t_state = TCPS_SYN_RECEIVED;
-               tp->t_timer[TCPT_KEEP] = tcp_keepinit;
+               tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, 
+                       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);
                tcpstat.tcps_accepts++;
                if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE | TH_CWR)) {
                        /* ECN-setup SYN */
                        tp->ecn_flags |= (TE_SETUPRECEIVED | TE_SENDIPECT);
                }
+
+#if CONFIG_IFEF_NOWINDOWSCALE
+               if (tcp_obey_ifef_nowindowscale && m->m_pkthdr.rcvif != NULL &&
+                   (m->m_pkthdr.rcvif->if_eflags & IFEF_NOWINDOWSCALE)) {
+                       /* Window scaling is not enabled on this interface */
+                       tp->t_flags &= ~TF_REQ_SCALE;
+               }
+#endif
                goto trimthenstep6;
                }
 
@@ -1739,8 +2863,19 @@ findpcb:
                    (SEQ_LEQ(th->th_ack, tp->snd_una) ||
                     SEQ_GT(th->th_ack, tp->snd_max))) {
                                rstreason = BANDLIM_RST_OPENPORT;
+                               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;
 
        /*
@@ -1760,10 +2895,22 @@ findpcb:
                    (SEQ_LEQ(th->th_ack, tp->iss) ||
                     SEQ_GT(th->th_ack, tp->snd_max))) {
                        rstreason = BANDLIM_UNLIMITED;
+                       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));
                                tp = tcp_drop(tp, ECONNREFUSED);
                                postevent(so, 0, EV_RESET);
                        }
@@ -1781,6 +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 */
@@ -1798,19 +2946,21 @@ findpcb:
                                tp->snd_scale = tp->requested_s_scale;
                                tp->rcv_scale = tp->request_r_scale;
                        }
-                       tp->rcv_adv += tp->rcv_wnd;
+                       tp->rcv_adv += min(tp->rcv_wnd, TCP_MAXWIN << tp->rcv_scale);
                        tp->snd_una++;          /* SYN is acked */
                        /*
                         * If there's data, delay ACK; if there's also a FIN
                         * ACKNOW will be turned on later.
                         */
-                       if (DELAY_ACK(tp) && tlen != 0) {
-                               tp->t_flags |= TF_DELACK;
-                               tp->t_unacksegs++;
+                       TCP_INC_VAR(tp->t_unacksegs, nlropkts);
+                       if (DELAY_ACK(tp, th) && tlen != 0 ) {
+                               if ((tp->t_flags & TF_DELACK) == 0) {
+                                       tp->t_flags |= TF_DELACK;
+                                       tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack);
+                               }
                        }
                        else {
                                tp->t_flags |= TF_ACKNOW;
-                               tp->t_unacksegs = 0;
                        }
                        /*
                         * Received <SYN,ACK> in SYN_SENT[*] state.
@@ -1818,30 +2968,52 @@ findpcb:
                         *      SYN_SENT  --> ESTABLISHED
                         *      SYN_SENT* --> FIN_WAIT_1
                         */
-                       tp->t_starttime = 0;
+                       tp->t_starttime = tcp_now;
+                       tcp_sbrcv_tstmp_check(tp);
                        if (tp->t_flags & TF_NEEDFIN) {
+                               DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                                       struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_1);
                                tp->t_state = TCPS_FIN_WAIT_1;
                                tp->t_flags &= ~TF_NEEDFIN;
                                thflags &= ~TH_SYN;
                        } else {
+                               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] = 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);
                        }
-                       /* soisconnected may lead to socket_unlock in case of upcalls,
-                        * make sure this is done when everything is setup.
+#if MPTCP
+                       /*
+                        * Do not send the connect notification for additional
+                        * subflows until ACK for 3-way handshake arrives.
                         */
-                       soisconnected(so);
+                       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-
-                *  taneous open.  If segment contains CC option and there is
-                *  a cached CC, apply TAO test; if it succeeds, connection is
-                *  half-synchronized.  Otherwise, do 3-way handshake:
-                *        SYN-SENT -> SYN-RECEIVED
-                *        SYN-SENT* -> SYN-RECEIVED*
-                */
+                       /*
+                        *  Received initial SYN in SYN-SENT[*] state => simul-
+                        *  taneous open.  If segment contains CC option and there is
+                        *  a cached CC, apply TAO test; if it succeeds, connection is
+                        *  half-synchronized.  Otherwise, do 3-way handshake:
+                        *        SYN-SENT -> SYN-RECEIVED
+                        *        SYN-SENT* -> SYN-RECEIVED*
+                        */
                        tp->t_flags |= TF_ACKNOW;
                        tp->t_timer[TCPT_REXMT] = 0;
+                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                               struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED);
                        tp->t_state = TCPS_SYN_RECEIVED;
 
                }
@@ -1967,10 +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_TCP_STATINC(ifp, rstinsynrcv);
                                so->so_error = ECONNREFUSED;
                                goto close;
 
@@ -1988,7 +3162,10 @@ trimthenstep6:
                                so->so_error = ECONNRESET;
                        close:
                                postevent(so, 0, EV_RESET);
-                               tp->t_state = TCPS_CLOSED;
+                               soevent(so,
+                                   (SO_FILT_HINT_LOCKED |
+                                   SO_FILT_HINT_CONNRESET));
+
                                tcpstat.tcps_drops++;
                                tp = tcp_close(tp);
                                break;
@@ -2005,10 +3182,6 @@ trimthenstep6:
                goto drop;
        }
 
-#if 0
-       lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
-#endif
-
        /*
         * RFC 1323 PAWS: If we have a timestamp reply on this segment
         * and it's less than ts_recent, drop it.
@@ -2034,6 +3207,15 @@ trimthenstep6:
                        tcpstat.tcps_rcvduppack++;
                        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);
+                               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)
                                goto dropafterack;
                        goto drop;
@@ -2049,6 +3231,7 @@ trimthenstep6:
         */
        if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
                rstreason = BANDLIM_RST_OPENPORT;
+               IF_TCP_STATINC(ifp, dospacket);
                goto dropwithreset;
        }
 
@@ -2080,14 +3263,25 @@ trimthenstep6:
                         * But keep on processing for RST or ACK.
                         */
                        tp->t_flags |= TF_ACKNOW;
-                       tp->t_unacksegs = 0;
+                       if (todrop == 1) {
+                               /* This could be a keepalive */
+                               soevent(so, SO_FILT_HINT_LOCKED |
+                                       SO_FILT_HINT_KEEPALIVE);
+                       }
                        todrop = tlen;
                        tcpstat.tcps_rcvduppack++;
-                       tcpstat.tcps_rcvdupbyte += todrop;
+                       tcpstat.tcps_rcvdupbyte += todrop; 
                } else {
                        tcpstat.tcps_rcvpartduppack++;
                        tcpstat.tcps_rcvpartdupbyte += todrop;
                }
+               if (nstat_collect) {
+                       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 */
                th->th_seq += todrop;
                tlen -= todrop;
@@ -2100,14 +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_TCP_STATINC(ifp, cleanup);
                goto dropwithreset;
        }
 
@@ -2143,7 +3342,6 @@ trimthenstep6:
                         */
                        if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
                                tp->t_flags |= TF_ACKNOW;
-                               tp->t_unacksegs = 0;
                                tcpstat.tcps_rcvwinprobe++;
                        } else
                                goto dropafterack;
@@ -2188,6 +3386,7 @@ trimthenstep6:
                tp = tcp_drop(tp, ECONNRESET);
                rstreason = BANDLIM_UNLIMITED;
                postevent(so, 0, EV_RESET);
+               IF_TCP_STATINC(ifp, synwindow);
                goto dropwithreset;
        }
 
@@ -2209,6 +3408,7 @@ trimthenstep6:
        /*
         * Ack processing.
         */
+
        switch (tp->t_state) {
 
        /*
@@ -2225,19 +3425,29 @@ trimthenstep6:
                        (TF_RCVD_SCALE|TF_REQ_SCALE)) {
                        tp->snd_scale = tp->requested_s_scale;
                        tp->rcv_scale = tp->request_r_scale;
+                       tp->snd_wnd = th->th_win << tp->snd_scale;
+                       tiwin = tp->snd_wnd;
                }
                /*
                 * Make transitions:
                 *      SYN-RECEIVED  -> ESTABLISHED
                 *      SYN-RECEIVED* -> FIN-WAIT-1
                 */
-               tp->t_starttime = 0;
+               tp->t_starttime = tcp_now;
+               tcp_sbrcv_tstmp_check(tp);
                if (tp->t_flags & TF_NEEDFIN) {
+                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                               struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_1);
                        tp->t_state = TCPS_FIN_WAIT_1;
                        tp->t_flags &= ~TF_NEEDFIN;
                } else {
+                       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] = 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);
                }
                /*
                 * If segment contains data or ACK, will call tcp_reass()
@@ -2245,15 +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 */
-
-               /* soisconnected may lead to socket_unlock in case of upcalls,
-                * make sure this is done when everything is setup.
+#if MPTCP
+               /*
+                * Do not send the connect notification for additional subflows
+                * until ACK for 3-way handshake arrives.
                 */
-               soisconnected(so);
+               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
@@ -2274,19 +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;
+
                                /*
-                                * 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
+                                * 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'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
@@ -2305,12 +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 ||
-                                        ((tcp_do_newreno || tp->sack_enable) &&
-                                         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;
                                                
                                                /*
@@ -2328,12 +3654,13 @@ trimthenstep6:
                                                }
                                        } else
                                                tp->snd_cwnd += tp->t_maxseg;
-                                       tp->t_unacksegs = 0;
+
+                                       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;
-                                       u_int win;
 
                                        /*
                                         * If we're doing sack, check to
@@ -2342,88 +3669,171 @@ 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 (tcp_do_newreno) {
+                                       } else {
                                                if (SEQ_LEQ(th->th_ack,
                                                    tp->snd_recover)) {
                                                        tp->t_dupacks = 0;
                                                        break;
                                                }
                                        }
-                                       win = min(tp->snd_wnd, tp->snd_cwnd) /
-                                           2 / tp->t_maxseg;
-                                       if (win < 2)
-                                               win = 2;
-                                       tp->snd_ssthresh = win * tp->t_maxseg;
-                                       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;
-                                       if (tp->sack_enable) {
+
+                                       /*
+                                        * 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
+                                        * before entering FR, call it
+                                        */
+                                       if (CC_ALGO(tp)->pre_fr != NULL)
+                                               CC_ALGO(tp)->pre_fr(tp);
+                                       ENTER_FASTRECOVERY(tp);
+                                       tp->t_timer[TCPT_REXMT] = 0;
+                                       if ((tp->ecn_flags & TE_ECN_ON)
+                                           == TE_ECN_ON) 
+                                               tp->ecn_flags |= TE_SENDCWR;
+
+                                       if (SACK_ENABLED(tp)) {
                                                tcpstat.tcps_sack_recovery_episode++;
                                                tp->sack_newdata = tp->snd_nxt;
                                                tp->snd_cwnd = tp->t_maxseg;
-                                               tp->t_unacksegs = 0;
+
+                                               /*
+                                                * 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;
                                        }
                                        tp->snd_nxt = th->th_ack;
                                        tp->snd_cwnd = tp->t_maxseg;
-                                       tp->t_unacksegs = 0;
                                        (void) tcp_output(tp);
                                        tp->snd_cwnd = tp->snd_ssthresh +
                                             tp->t_maxseg * tp->t_dupacks;
                                        if (SEQ_GT(onxt, tp->snd_nxt))
                                                tp->snd_nxt = onxt;
+                                       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;
                }
                /*
                 * If the congestion window was inflated to account
                 * for the other side's cached packets, retract it.
                 */
-               if (tcp_do_newreno || tp->sack_enable) {
-                       if (IN_FASTRECOVERY(tp)) {
-                               if (SEQ_LT(th->th_ack, tp->snd_recover)) {
-                                       if (tp->sack_enable)
-                                               tcp_sack_partialack(tp, th);
-                                       else
-                                               tcp_newreno_partial_ack(tp, th);
-                               } else {
-                                       /*
-                                        * Out of fast recovery.
-                                        * Window inflation should have left us
-                                        * with approximately snd_ssthresh
-                                        * outstanding data.
-                                        * But in case we would be inclined to
-                                        * send a burst, better to do it via
-                                        * the slow start mechanism.
-                                        */
-                                       if (SEQ_GT(th->th_ack +
-                                                       tp->snd_ssthresh,
-                                                  tp->snd_max))
-                                               tp->snd_cwnd = tp->snd_max -
-                                                               th->th_ack +
-                                                               tp->t_maxseg;
-                                       else
-                                               tp->snd_cwnd = tp->snd_ssthresh;
-                               }
+               if (IN_FASTRECOVERY(tp)) {
+                       if (SEQ_LT(th->th_ack, tp->snd_recover)) {
+                               /*
+                                * 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);                        
+                               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);
+
+                               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 {
-                       if (tp->t_dupacks >= tcprexmtthresh &&
-                           tp->snd_cwnd > tp->snd_ssthresh)
-                               tp->snd_cwnd = tp->snd_ssthresh;
+                       /*
+                        * We were not in fast recovery. Reset the
+                        * duplicate ack counter.
+                        */
+                       tp->t_dupacks = 0;
+                       tp->t_rexmtthresh = tcprexmtthresh;
                }
-               tp->t_dupacks = 0;
-               tp->t_bytes_acked = 0;
+
+
                /*
                 * If we reach this point, ACK is not a duplicate,
                 *     i.e., it ACKs something we sent.
@@ -2447,52 +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 && 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 */ 
-               }
-
-               /*
-                * 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)) {
-                       if (!tp->t_rttlow || tp->t_rttlow > tcp_now - to.to_tsecr)
-                               tp->t_rttlow = 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)) {
-                       if (!tp->t_rttlow || tp->t_rttlow > tcp_now - tp->t_rtttime)
-                               tp->t_rttlow = tcp_now - tp->t_rtttime;
-                       tcp_xmit_timer(tp, 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
@@ -2502,115 +3882,85 @@ 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] = 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;
 
-               /*
-                * When new data is acked, open the congestion window.
-                */
+
                if ((thflags & TH_ECE) != 0 &&
-                       (tp->ecn_flags & TE_SETUPSENT) != 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)) &&
-                               !(tcp_do_newreno && SEQ_LEQ(th->th_ack, tp->snd_recover))) {
+                       if (!IN_FASTRECOVERY(tp)) {
                                tcp_reduce_congestion_window(tp);
+                               tp->ecn_flags |= (TE_INRECOVERY|TE_SENDCWR);
+                               tcp_ccdbg_trace(tp, th, TCP_CC_ECN_RCVD);
                        }
-               } else if ((!tcp_do_newreno && !tp->sack_enable) ||
-                   !IN_FASTRECOVERY(tp)) {
-                       /*
-                        * RFC 3465 - Appropriate Byte Counting.
-                        *
-                        * If the window is currently less than ssthresh,
-                        * open the window by the number of bytes ACKed by
-                        * the last ACK, however clamp the window increase
-                        * to an upper limit "L".
-                        *
-                        * In congestion avoidance phase, open the window by
-                        * one segment each time "bytes_acked" grows to be
-                        * greater than or equal to the congestion window.
-                        */
-
-                       register u_int cw = tp->snd_cwnd;
-                       register u_int incr = tp->t_maxseg;
-
-                       if ((acked > incr) && tcp_do_rfc3465) {
-                               if (cw >= tp->snd_ssthresh) {
-                                       tp->t_bytes_acked += acked;
-                                       if (tp->t_bytes_acked >= cw) {
-                                       /* Time to increase the window. */
-                                               tp->t_bytes_acked -= cw;
-                                       } else {
-                                       /* No need to increase yet. */
-                                               incr = 0;
-                                       }
-                               } else {
-                                       /*
-                                        * If the user explicitly enables RFC3465
-                                        * use 2*SMSS for the "L" param.  Otherwise
-                                        * use the more conservative 1*SMSS.
-                                        *
-                                        * (See RFC 3465 2.3 Choosing the Limit)
-                                        */
-                                       u_int abc_lim;
-
-                                       abc_lim = (tcp_do_rfc3465 == 0) ?
-                                           incr : incr * 2;
-                                       incr = lmin(acked, abc_lim);
-                               }
-                       }
-                       else {
-                               /*
-                                * If the window gives us less than ssthresh packets
-                                * in flight, open exponentially (segsz per packet).
-                                * Otherwise open linearly: segsz per window
-                                * (segsz^2 / cwnd per packet).
-                                */
-               
-                                       if (cw >= tp->snd_ssthresh) {
-                                               incr = incr * incr / cw;
-                                       }
-                       }
-
+               }
 
-                       tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale);
+               /*
+                * When new data is acked, open the congestion window.
+                * The specifics of how this is achieved are up to the
+                * congestion control algorithm in use for this connection.
+                *
+                * The calculations in this function assume that snd_una is
+                * not updated yet.
+                */
+               if (!IN_FASTRECOVERY(tp)) {
+                       if (CC_ALGO(tp)->ack_rcvd != NULL)
+                               CC_ALGO(tp)->ack_rcvd(tp, th);
+                       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;
                }
                /* detect una wraparound */
-               if ((tcp_do_newreno || tp->sack_enable) &&
-                   !IN_FASTRECOVERY(tp) &&
+               if ( !IN_FASTRECOVERY(tp) &&
                    SEQ_GT(tp->snd_una, tp->snd_recover) &&
                    SEQ_LEQ(th->th_ack, tp->snd_recover))
                        tp->snd_recover = th->th_ack - 1;
-               if ((tcp_do_newreno || tp->sack_enable) &&
-                   IN_FASTRECOVERY(tp) &&
+
+               if (IN_FASTRECOVERY(tp) &&
                    SEQ_GEQ(th->th_ack, tp->snd_recover))
                        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;
                }
                if (SEQ_LT(tp->snd_nxt, tp->snd_una))
                        tp->snd_nxt = tp->snd_una;
-                       
+               if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 &&
+                       tp->t_bwmeas != NULL)
+                       tcp_bwmeas_check(tp);
+
                /*
                 * sowwakeup must happen after snd_una, et al. are updated so that
                 * the sequence numbers are in sync with so_snd
@@ -2629,18 +3979,26 @@ 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) {
-                                       tp->t_timer[TCPT_2MSL] = tcp_maxidle;
-                                       add_to_time_wait(tp);
-                                       soisdisconnected(so);
+                                       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);
                                tp->t_state = TCPS_FIN_WAIT_2;
-                               goto drop;
+                               /* fall through and make sure we also recognize 
+                                * data ACKed with the FIN 
+                                */
                        }
+                       tp->t_flags |= TF_ACKNOW;
                        break;
 
                /*
@@ -2651,18 +4009,21 @@ process_ACK:
                 */
                case TCPS_CLOSING:
                        if (ourfinisacked) {
+                               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 &&
-                                   tp->t_starttime < (u_long)tcp_msl)
-                                       tp->t_timer[TCPT_2MSL] =
-                                           tp->t_rxtcur * TCPTV_TWTRUNC;
-                               else
-                                       tp->t_timer[TCPT_2MSL] = 2 * tcp_msl;
-                               add_to_time_wait(tp);
-                               soisdisconnected(so);
+                               if (tp->t_flagsext & TF_NOTIMEWAIT) {
+                                       tp->t_flags |= TF_CLOSING;
+                               } else {
+                                       add_to_time_wait(tp, 2 * tcp_msl);
+                               }
+                               isconnected = FALSE;
+                               isdisconnected = TRUE;
                        }
+                       tp->t_flags |= TF_ACKNOW;
                        break;
 
                /*
@@ -2684,10 +4045,29 @@ process_ACK:
                 * it and restart the finack timer.
                 */
                case TCPS_TIME_WAIT:
-                       tp->t_timer[TCPT_2MSL] = 2 * tcp_msl;
-                       add_to_time_wait(tp);
+                       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:
@@ -2758,14 +4138,14 @@ step6:
                 * but if two URG's are pending at once, some out-of-band
                 * data may creep in... ick.
                 */
-               if (th->th_urp <= (u_long)tlen
+               if (th->th_urp <= (u_int32_t)tlen
 #if SO_OOBINLINE
                     && (so->so_options & SO_OOBINLINE) == 0
 #endif
                     )
                        tcp_pulloutofband(so, th, m,
                                drop_hdrlen);   /* hdr drop is delayed */
-       } else
+       } else {
                /*
                 * If no out of band data is expected,
                 * pull receive urgent pointer along
@@ -2773,8 +4153,27 @@ step6:
                 */
                if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
                        tp->rcv_up = tp->rcv_nxt;
-dodata:                                                        /* XXX */
+       }
+dodata:
+
+       /* Set socket's connect or disconnect state correcly before doing data.
+        * The following might unlock the socket if there is an upcall or a socket
+        * filter.
+        */
+       if (isconnected) {
+               soisconnected(so);
+       } else if (isdisconnected) {
+               soisdisconnected(so);
+       }
 
+       /* Let's check the state of pcb just to make sure that it did not get closed 
+        * when we unlocked above
+        */
+       if (inp->inp_state == INPCB_STATE_DEAD) {
+               /* Just drop the packet that we are processing and return */
+               goto drop;
+       }
+       
        /*
         * Process the segment text, merging it into the TCP sequencing queue,
         * and arranging for acknowledgment of receipt if necessary.
@@ -2783,7 +4182,7 @@ dodata:                                                   /* XXX */
         * case PRU_RCVD).  If a FIN has already been received on this
         * connection then we just ignore the text.
         */
-       if ((tlen || (thflags&TH_FIN)) &&
+       if ((tlen || (thflags & TH_FIN)) &&
            TCPS_HAVERCVDFIN(tp->t_state) == 0) {
                tcp_seq save_start = th->th_seq;
                tcp_seq save_end = th->th_seq + tlen;
@@ -2803,30 +4202,59 @@ dodata:                                                 /* XXX */
                if (th->th_seq == tp->rcv_nxt &&
                    LIST_EMPTY(&tp->t_segq) &&
                    TCPS_HAVEESTABLISHED(tp->t_state)) {
-                       if (DELAY_ACK(tp) && ((tp->t_flags & TF_ACKNOW) == 0)) {
-                               tp->t_flags |= TF_DELACK;
-                               tp->t_unacksegs++;
+                       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);
+                               }
                        }         
                        else {
-                               tp->t_unacksegs = 0;
                                tp->t_flags |= TF_ACKNOW;
                        }
                        tp->rcv_nxt += tlen;
                        thflags = th->th_flags & TH_FIN;
-                       tcpstat.tcps_rcvpack++;
+                       TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts);
                        tcpstat.tcps_rcvbyte += tlen;
-                       ND6_HINT(tp);
-                       if (sbappendstream(&so->so_rcv, m))
+                       if (nstat_collect) {
+                               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);
+                               }
+                               INP_ADD_STAT(inp, cell, wifi, wired,
+                                   rxbytes, tlen);
+                       }
+                       tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen);
+                       so_recv_data_stat(so, m, drop_hdrlen);
+                       
+                       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;
-                       tp->t_unacksegs = 0;
                }
 
-               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
@@ -2844,14 +4272,6 @@ dodata:                                                  /* XXX */
                        }
                                
                }
-               /*
-                * Note the amount of data that peer has sent into
-                * our window, in order to estimate the sender's
-                * buffer size.
-                */
-               len = (u_int)(so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt));
-               if (len > so->so_rcv.sb_maxused)
-                       so->so_rcv.sb_maxused = len;
        } else {
                m_freem(m);
                thflags &= ~TH_FIN;
@@ -2866,21 +4286,21 @@ dodata:                                                 /* XXX */
                        socantrcvmore(so);
                        postevent(so, 0, EV_FIN);
                        /*
-                        *  If connection is half-synchronized
-                        *  (ie NEEDSYN flag on) then delay ACK,
                         * If connection is half-synchronized
                         * (ie NEEDSYN flag on) then delay ACK,
                         * so it may be piggybacked when SYN is sent.
                         * Otherwise, since we received a FIN then no
                         * more input can be expected, send ACK now.
                         */
-                       if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) {
-                               tp->t_flags |= TF_DELACK;
-                               tp->t_unacksegs++;
+                       TCP_INC_VAR(tp->t_unacksegs, nlropkts);
+                       if (DELAY_ACK(tp, th) && (tp->t_flags & TF_NEEDSYN)) {
+                               if ((tp->t_flags & TF_DELACK) == 0) {
+                                       tp->t_flags |= TF_DELACK;
+                                       tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack);
+                               }
                        }
                        else {
                                tp->t_flags |= TF_ACKNOW;
-                               tp->t_unacksegs = 0;
                        }
                        tp->rcv_nxt++;
                }
@@ -2891,8 +4311,10 @@ dodata:                                                  /* XXX */
                 * enter the CLOSE_WAIT state.
                 */
                case TCPS_SYN_RECEIVED:
-                       tp->t_starttime = 0;
+                       tp->t_starttime = tcp_now;
                case TCPS_ESTABLISHED:
+                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                               struct tcpcb *, tp, int32_t, TCPS_CLOSE_WAIT);
                        tp->t_state = TCPS_CLOSE_WAIT;
                        break;
 
@@ -2901,6 +4323,8 @@ dodata:                                                   /* XXX */
                 * enter the CLOSING state.
                 */
                case TCPS_FIN_WAIT_1:
+                       DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp,
+                               struct tcpcb *, tp, int32_t, TCPS_CLOSING);
                        tp->t_state = TCPS_CLOSING;
                        break;
 
@@ -2910,21 +4334,18 @@ dodata:                                                 /* XXX */
                 * standard timers.
                 */
                case TCPS_FIN_WAIT_2:
+                       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 &&
-                           tp->t_starttime < (u_long)tcp_msl) {
-                               tp->t_timer[TCPT_2MSL] =
-                                   tp->t_rxtcur * TCPTV_TWTRUNC;
-                               /* For transaction client, force ACK now. */
-                               tp->t_flags |= TF_ACKNOW;
-                               tp->t_unacksegs = 0;
+                       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);
                        }
-                       else
-                               tp->t_timer[TCPT_2MSL] = 2 * tcp_msl;
-
-                       add_to_time_wait(tp);
                        soisdisconnected(so);
                        break;
 
@@ -2932,8 +4353,7 @@ dodata:                                                   /* XXX */
                 * In TIME_WAIT state restart the 2 MSL time_wait timer.
                 */
                case TCPS_TIME_WAIT:
-                       tp->t_timer[TCPT_2MSL] = 2 * tcp_msl;
-                       add_to_time_wait(tp);
+                       add_to_time_wait(tp, 2 * tcp_msl);
                        break;
                }
        }
@@ -2947,9 +4367,12 @@ dodata:                                                  /* XXX */
         * Return any desired output.
         */
        if (needoutput || (tp->t_flags & TF_ACKNOW)) {
-               tp->t_unacksegs = 0;
                (void) tcp_output(tp);
        }
+
+       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;
@@ -2974,6 +4397,7 @@ dropafterack:
            (SEQ_GT(tp->snd_una, th->th_ack) ||
             SEQ_GT(th->th_ack, tp->snd_max)) ) {
                rstreason = BANDLIM_RST_OPENPORT;
+               IF_TCP_STATINC(ifp, dospacket);
                goto dropwithreset;
        }
 #if TCPDEBUG
@@ -2983,8 +4407,9 @@ dropafterack:
 #endif
        m_freem(m);
        tp->t_flags |= TF_ACKNOW;
-       tp->t_unacksegs = 0;
        (void) tcp_output(tp);
+
+       /* Don't need to check timer state as we should have done it during tcp_output */
        tcp_unlock(so, 1, 0);
        KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0);
        return;
@@ -3025,25 +4450,27 @@ 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, m->m_pkthdr.rcvif);
+                   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, m->m_pkthdr.rcvif);
+                   (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)) {
+               tcp_unlock(so, 1, 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);
        return;
 dropnosock:
@@ -3063,15 +4490,15 @@ drop:
                (void) soabort(so); 
                tcp_unlock(so, 1, 0);
        }
-       else
-               if (nosock == 0)
-                       tcp_unlock(so, 1, 0);
+       else if (nosock == 0) {
+               tcp_unlock(so, 1, 0);
+       }
        KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0);
        return;
 }
 
 static void
-tcp_dooptions(tp, cp, cnt, th, to)
+tcp_dooptions(tp, cp, cnt, th, to, input_ifscope)
 /*
  * Parse TCP options and place in tcpopt.
  */
@@ -3080,6 +4507,7 @@ tcp_dooptions(tp, cp, cnt, th, to)
        int cnt;
        struct tcphdr *th;
        struct tcpopt *to;
+       unsigned int input_ifscope;
 {
        u_short mss = 0;
        int opt, optlen;
@@ -3116,6 +4544,7 @@ tcp_dooptions(tp, cp, cnt, th, to)
                                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;
@@ -3130,7 +4559,6 @@ tcp_dooptions(tp, cp, cnt, th, to)
                        bcopy((char *)cp + 6,
                            (char *)&to->to_tsecr, sizeof(to->to_tsecr));
                        NTOHL(to->to_tsecr);
-
                        /*
                         * A timestamp received in a SYN makes
                         * it ok to send timestamp requests and replies.
@@ -3156,10 +4584,16 @@ tcp_dooptions(tp, cp, cnt, th, to)
                        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)
-               tcp_mss(tp, mss);       /* sets t_maxseg */
+               tcp_mss(tp, mss, input_ifscope);        /* sets t_maxseg */
 }
 
 /*
@@ -3198,28 +4632,138 @@ tcp_pulloutofband(so, th, m, off)
        panic("tcp_pulloutofband");
 }
 
+uint32_t
+get_base_rtt(struct tcpcb *tp) 
+{
+       uint32_t base_rtt = 0, i;
+       for (i = 0; i < N_RTT_BASE; ++i) {
+               if (tp->rtt_hist[i] != 0 &&
+                       (base_rtt == 0 || tp->rtt_hist[i] < base_rtt))
+                       base_rtt = tp->rtt_hist[i];
+       }
+       return base_rtt;
+}
+
+/* Each value of RTT base represents the minimum RTT seen in a minute.
+ * We keep upto N_RTT_BASE minutes worth of history.
+ */
+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) {
+#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];
+               }
+               tp->rtt_hist[0] = rtt;
+               tp->rtt_count = 0;
+       } else {
+               tp->rtt_hist[0] = min(tp->rtt_hist[0], 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++;
+
+       if (rtt > 0) {
+               tp->t_rttcur = rtt;
+               update_base_rtt(tp, rtt);
+       }
+
        if (tp->t_srtt != 0) {
                /*
                 * srtt is stored as fixed point with 5 bits after the
-                * binary point (i.e., scaled by 8).  The following magic
+                * binary point (i.e., scaled by 32).  The following magic
                 * is equivalent to the smoothing algorithm in rfc793 with
                 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
-                * point).  Adjust rtt to origin 0.
+                * 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
+                * tcp_now, this extra adjustment is not needed.
                 */
-               delta = ((rtt - 1) << TCP_DELTA_SHIFT)
+               delta = (rtt << TCP_DELTA_SHIFT)
                        - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
 
                if ((tp->t_srtt += delta) <= 0)
@@ -3240,8 +4784,9 @@ tcp_xmit_timer(tp, rtt)
                delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
                if ((tp->t_rttvar += delta) <= 0)
                        tp->t_rttvar = 1;
-               if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
-                   tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
+               if (tp->t_rttbest == 0  || 
+                       tp->t_rttbest > (tp->t_srtt + tp->t_rttvar))
+                       tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
        } else {
                /*
                 * No rtt measurement yet - use the unsmoothed rtt.
@@ -3250,10 +4795,14 @@ tcp_xmit_timer(tp, rtt)
                 */
                tp->t_srtt = rtt << TCP_RTT_SHIFT;
                tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
-               tp->t_rttbest = 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->t_rxtstart = 0;
 
        /*
         * the retransmit should happen at rtt + 4 * rttvar.
@@ -3267,7 +4816,8 @@ tcp_xmit_timer(tp, rtt)
         * the minimum feasible timer (which is 2 ticks).
         */
        TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
-                     max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
+               max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX, 
+               TCP_ADD_REXMTSLOP(tp));
 
        /*
         * We received an ack for a packet that wasn't retransmitted;
@@ -3284,6 +4834,7 @@ tcp_maxmtu(struct rtentry *rt)
 {
        unsigned int maxmtu;
 
+       RT_LOCK_ASSERT_HELD(rt);
        if (rt->rt_rmx.rmx_mtu == 0)
                maxmtu = rt->rt_ifp->if_mtu;
        else
@@ -3297,11 +4848,21 @@ static inline unsigned int
 tcp_maxmtu6(struct rtentry *rt)
 {
        unsigned int maxmtu;
-
+       struct nd_ifinfo *ndi;
+
+       RT_LOCK_ASSERT_HELD(rt);
+       lck_rw_lock_shared(nd_if_rwlock);
+       if ((ndi = ND_IFINFO(rt->rt_ifp)) != NULL && !ndi->initialized)
+               ndi = NULL;
+       if (ndi != NULL)
+               lck_mtx_lock(&ndi->lock);
        if (rt->rt_rmx.rmx_mtu == 0)
                maxmtu = IN6_LINKMTU(rt->rt_ifp);
        else
                maxmtu = MIN(rt->rt_rmx.rmx_mtu, IN6_LINKMTU(rt->rt_ifp));
+       if (ndi != NULL)
+               lck_mtx_unlock(&ndi->lock);
+       lck_rw_done(nd_if_rwlock);
 
        return (maxmtu);
 }
@@ -3318,9 +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
@@ -3333,19 +4894,20 @@ tcp_maxmtu6(struct rtentry *rt)
  *
  */
 void
-tcp_mss(tp, offer)
+tcp_mss(tp, offer, input_ifscope)
        struct tcpcb *tp;
        int offer;
+       unsigned int input_ifscope;
 {
        register struct rtentry *rt;
        struct ifnet *ifp;
        register int rtt, mss;
-       u_long bufsize;
+       u_int32_t bufsize;
        struct inpcb *inp;
        struct socket *so;
        struct rmxp_tao *taop;
        int origoffer = offer;
-       u_long sb_max_corrected;
+       u_int32_t sb_max_corrected;
        int isnetlocal = 0;
 #if INET6
        int isipv6;
@@ -3360,36 +4922,33 @@ tcp_mss(tp, offer)
 #else
 #define min_protoh  (sizeof (struct tcpiphdr))
 #endif
-       lck_mtx_lock(rt_mtx);
+
 #if INET6
        if (isipv6) {
-               rt = tcp_rtlookup6(inp);
-               if (rt && (IN6_IS_ADDR_LOOPBACK(&inp->in6p_faddr) || IN6_IS_ADDR_LINKLOCAL(&inp->in6p_faddr) || rt->rt_gateway->sa_family == AF_LINK))
-                                isnetlocal = TRUE;
+               rt = tcp_rtlookup6(inp, input_ifscope);
        }
        else
 #endif /* INET6 */
        {
-               rt = tcp_rtlookup(inp);
-               if (rt && (rt->rt_gateway->sa_family == AF_LINK ||
-                       rt->rt_ifp->if_flags & IFF_LOOPBACK)) 
-                        isnetlocal = TRUE;
+               rt = tcp_rtlookup(inp, input_ifscope);
        }
+       isnetlocal = (tp->t_flags & TF_LOCAL);
+
        if (rt == NULL) {
                tp->t_maxopd = tp->t_maxseg =
 #if INET6
                isipv6 ? tcp_v6mssdflt :
 #endif /* INET6 */
                tcp_mssdflt;
-               lck_mtx_unlock(rt_mtx);
                return;
        }
        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) {
@@ -3435,32 +4994,11 @@ tcp_mss(tp, offer)
         * or rttvar.  Convert from the route-table units
         * to scaled multiples of the slow timeout timer.
         */
-       if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
-               /*
-                * XXX the lock bit for RTT indicates that the value
-                * is also a minimum value; this is subject to time.
-                */
-               if (rt->rt_rmx.rmx_locks & RTV_RTT)
-                       tp->t_rttmin = rtt / (RTM_RTTUNIT / TCP_RETRANSHZ);
-               else
-                       tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCP_RETRANSHZ;
-               tp->t_srtt = rtt / (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTT_SCALE));
-               tcpstat.tcps_usedrtt++;
-               if (rt->rt_rmx.rmx_rttvar) {
-                       tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
-                           (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTTVAR_SCALE));
-                       tcpstat.tcps_usedrttvar++;
-               } else {
-                       /* default variation is +- 1 rtt */
-                       tp->t_rttvar =
-                           tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
-               }
-               TCPT_RANGESET(tp->t_rxtcur,
-                             ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
-                             tp->t_rttmin, TCPTV_REXMTMAX);
+       if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt) != 0) {
+               tcp_getrt_rtt(tp, rt);
+       } else {
+               tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCPTV_REXMTMIN;
        }
-       else
-               tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCP_RETRANSHZ;
 
 #if INET6
        mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt));
@@ -3498,8 +5036,12 @@ tcp_mss(tp, offer)
            (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.
@@ -3540,26 +5082,32 @@ tcp_mss(tp, offer)
                (void)sbreserve(&so->so_rcv, bufsize);
        }
 
-       /*
-        * Set the slow-start flight size depending on whether this
-        * is a local network or not.
-        */
-       if (isnetlocal)
-               tp->snd_cwnd = mss * ss_fltsz_local;
-       else 
-               tp->snd_cwnd = mss * ss_fltsz;
+       set_tcp_stream_priority(so);
 
        if (rt->rt_rmx.rmx_ssthresh) {
                /*
                 * 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++;
+       } else {
+               tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
        }
-       lck_mtx_unlock(rt_mtx);
+
+       /*
+        * Set the slow-start flight size depending on whether this
+        * is a local network or not.
+        */
+       if (CC_ALGO(tp)->cwnd_init != NULL)
+               CC_ALGO(tp)->cwnd_init(tp);
+
+       tcp_ccdbg_trace(tp, NULL, TCP_CC_CWND_INIT);
+
+       /* Route locked during lookup above */
+       RT_UNLOCK(rt);
 }
 
 /*
@@ -3583,15 +5131,14 @@ tcp_mssopt(tp)
 #else
 #define min_protoh  (sizeof (struct tcpiphdr))
 #endif
-       lck_mtx_lock(rt_mtx);
+
 #if INET6
        if (isipv6)
-               rt = tcp_rtlookup6(tp->t_inpcb);
+               rt = tcp_rtlookup6(tp->t_inpcb, IFSCOPE_NONE);
        else
 #endif /* INET6 */
-       rt = tcp_rtlookup(tp->t_inpcb);
+       rt = tcp_rtlookup(tp->t_inpcb, IFSCOPE_NONE);
        if (rt == NULL) {
-               lck_mtx_unlock(rt_mtx);
                return (
 #if INET6
                        isipv6 ? tcp_v6mssdflt :
@@ -3614,14 +5161,15 @@ tcp_mssopt(tp)
 #else
        mss = tcp_maxmtu(rt);
 #endif
-       lck_mtx_unlock(rt_mtx);
+       /* Route locked during lookup above */
+       RT_UNLOCK(rt);
        return (mss - min_protoh);
 }
 
 /*
  * On a partial ack arrives, force the retransmission of the
  * next unacknowledged segment.  Do not clear tp->t_dupacks.
- * By setting snd_nxt to ti_ack, this forces retransmission timer to
+ * By setting snd_nxt to th_ack, this forces retransmission timer to
  * be started again.
  */
 static void
@@ -3630,8 +5178,9 @@ tcp_newreno_partial_ack(tp, th)
        struct tcphdr *th;
 {
                tcp_seq onxt = tp->snd_nxt;
-               u_long  ocwnd = tp->snd_cwnd;
+               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;
                /*
@@ -3639,9 +5188,8 @@ 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;
-               tp->t_unacksegs = 0;
                (void) tcp_output(tp);
                tp->snd_cwnd = ocwnd;
                if (SEQ_GT(onxt, tp->snd_nxt))
@@ -3650,8 +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;
@@ -3672,29 +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;
@@ -3708,67 +5288,217 @@ 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)) {
+                       if (lck_mtx_try_lock(&inp->inpcb_mtx)) {
                                so->so_usecount++;
-                               if ((so->so_usecount == 2) && so->so_state & SS_INCOMP) 
+                               if ((so->so_usecount == 2) && 
+                                   (so->so_state & SS_INCOMP) &&
+                                   !(so->so_flags & SOF_INCOMP_INPROGRESS))  {
                                        break;
-                               else {/* don't use if beeing 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.
+                                * Only drop the inp_wntcnt reference.
+                                */
+                               in_pcb_checkstate(inp, WNT_RELEASE, 1);
                        }
                }
                so = sonext;
                
        }
-       if (!so)
-               return 0;
-
-       TAILQ_REMOVE(&head->so_incomp, so, so_list);
-       tcp_unlock(head, 0, 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);
-               tcp_lock(head, 0, 0);
-               return 0;
+               return (0);
        }
 
+found_victim:
        if (so->so_usecount != 2 || !(so->so_state & SS_INCOMP)) {
-               /* do not discard: that socket is beeing accepted */
+               /* do not discard: that socket is being accepted */
                tcp_unlock(so, 1, 0);
-               tcp_lock(head, 0, 0);
-               return 0;
+               return (0);
        }
 
-       so->so_head = NULL;
+       TAILQ_REMOVE(&head->so_incomp, so, so_list);
+       tcp_unlock(head, 0, 0);
 
-       /* 
-        * We do not want to lose track of the PCB right away in case we receive 
-        * more segments from the peer
-        */
+       lck_mtx_assert(&inp->inpcb_mtx, LCK_MTX_ASSERT_OWNED);
        tp = sototcpcb(so);
        so->so_flags |= SOF_OVERFLOW;
-       tp->t_state = TCPS_TIME_WAIT;
-       (void) tcp_close(tp);
-       tp->t_unacksegs = 0;
+       so->so_head = NULL;
+
+       tcp_close(tp);
+       if (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING) {
+               /* 
+                * 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 
+                */
+               tcp_unlock(so, 0, 0);
+
+               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
+                        */
+                       tcp_unlock(so, 1, 0);
+               } else {
+
+                       /* Drop the reference held for this function */
+                       so->so_usecount--;
+
+                       in_pcbdispose(inp);
+               }
+               lck_rw_done(tcbinfo.ipi_lock);
+       }
        tcpstat.tcps_drops++;
-       tcp_canceltimers(tp);
-       add_to_time_wait(tp);
-       
-       tcp_unlock(so, 1, 0);
+
        tcp_lock(head, 0, 0);
        head->so_incqlen--;
        head->so_qlen--;
-       return 1;
+       return(1);
+}
+
+/* Set background congestion control on a socket */
+void
+tcp_set_background_cc(struct socket *so)
+{
+       tcp_set_new_cc(so, TCP_CC_ALGO_BACKGROUND_INDEX);
+}
+
+/* Set foreground congestion control on a socket */
+void
+tcp_set_foreground_cc(struct socket *so)
+{
+       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
+tcp_set_new_cc(struct socket *so, uint16_t cc_index)
+{
+       struct inpcb *inp = sotoinpcb(so);
+       struct tcpcb *tp = intotcpcb(inp);
+       u_char old_cc_index = 0;
+       if (tp->tcp_cc_index != cc_index) {
+
+               old_cc_index = tp->tcp_cc_index;
+
+               if (CC_ALGO(tp)->cleanup != NULL)
+                       CC_ALGO(tp)->cleanup(tp);
+               tp->tcp_cc_index = cc_index;
+
+               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);
+       }
+}
+
+void
+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
+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
+inp_fc_unthrottle_tcp(struct inpcb *inp)
+{
+       struct tcpcb *tp = inp->inp_ppcb;
+       /*
+        * Back off the slow-start threshold and enter
+        * congestion avoidance phase
+        */
+       if (CC_ALGO(tp)->pre_fr != NULL)
+               CC_ALGO(tp)->pre_fr(tp);
+
+       tp->snd_cwnd = tp->snd_ssthresh;
+
+       /*
+        * Restart counting for ABC as we changed the
+        * congestion window just now.
+        */
+       tp->t_bytes_acked = 0;
+
+       /* Reset retransmit shift as we know that the reason
+        * for delay in sending a packet is due to flow 
+        * control on the outgoing interface. There is no need
+        * to backoff retransmit timer.
+        */
+       tp->t_rxtshift = 0;
+
+       /*
+        * Start the output stream again. Since we are
+        * not retransmitting data, do not reset the
+        * retransmit timer or rtt calculation.
+        */
+       tcp_output(tp);
+}
+    
 static int
 tcp_getstat SYSCTL_HANDLER_ARGS
 {
@@ -3776,6 +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);
        }
@@ -3786,7 +5551,155 @@ tcp_getstat SYSCTL_HANDLER_ARGS
 
 }
 
-SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RD, 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
@@ -3814,5 +5727,5 @@ sysctl_rexmtthresh SYSCTL_HANDLER_ARGS
        return (0);
 }
 
-SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmt_thresh, CTLTYPE_INT|CTLFLAG_RW,
+SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmt_thresh, CTLTYPE_INT|CTLFLAG_RW | CTLFLAG_LOCKED,
        &tcprexmtthresh, 0, &sysctl_rexmtthresh, "I", "Duplicate ACK Threshold for Fast Retransmit");