xnu-1228.3.13.tar.gz

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

diff --git a/bsd/netinet/tcp_output.c b/bsd/netinet/tcp_output.c
index 250d4a2d66ef6c9582fef571065d6718a3cdf53c..db82d4d90a5517ce13db2c728c088b6d7619ea79 100644 (file)
--- a/bsd/netinet/tcp_output.c
+++ b/bsd/netinet/tcp_output.c
@@ -167,8 +167,10 @@ extern int ipsec_bypass;
 
 extern int slowlink_wsize;     /* window correction for slow links */
 extern u_long  route_generation;
+#if IPFIREWALL
 extern int fw_enable;          /* firewall check for packet chaining */
 extern int fw_bypass;          /* firewall check: disable packet chaining if there is rules */
+#endif /* IPFIREWALL */
 
 extern vm_size_t       so_cache_zone_element_size;
 
@@ -677,10 +679,19 @@ after_sack_rexmit:
                long adv = lmin(recwin, (long)TCP_MAXWIN << tp->rcv_scale) -
                        (tp->rcv_adv - tp->rcv_nxt);
 
-               if (adv >= (long) (2 * tp->t_maxseg))
-                       goto send;
-               if (2 * adv >= (long) so->so_rcv.sb_hiwat)
-                       goto send;
+               if (adv >= (long) (2 * tp->t_maxseg)) {
+                       
+                       /* 
+                        * Update only if the resulting scaled value of the window changed, or
+                        * if there is a change in the sequence since the last ack.
+                        * This avoids what appears as dupe ACKS (see rdar://5640997)
+                        */
+
+                       if ((tp->last_ack_sent != tp->rcv_nxt) || (((recwin + adv) >> tp->rcv_scale) > recwin)) 
+                               goto send;
+               }
+               if (2 * adv >= (long) so->so_rcv.sb_hiwat) 
+                               goto send;
        }
 
        /*
@@ -1239,6 +1250,8 @@ send:
                tp->sackhint.sack_bytes_rexmit += len;
        }
        th->th_ack = htonl(tp->rcv_nxt);
+       tp->last_ack_sent = tp->rcv_nxt;
+
        if (optlen) {
                bcopy(opt, th + 1, optlen);
                th->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
@@ -1623,6 +1636,11 @@ tcp_ip_output(struct socket *so, struct tcpcb *tp, struct mbuf *pkt,
        boolean_t chain;
        boolean_t unlocked = FALSE;
 
+       /* Make sure ACK/DELACK conditions are cleared before
+        * we unlock the socket.
+        */
+
+       tp->t_flags &= ~(TF_ACKNOW | TF_DELACK);
        /*
         * If allowed, unlock TCP socket while in IP 
         * but only if the connection is established and
@@ -1642,11 +1660,15 @@ tcp_ip_output(struct socket *so, struct tcpcb *tp, struct mbuf *pkt,
         * - there is a non default rule set for the firewall
         */
 
-       chain = tcp_packet_chaining > 1 &&
+       chain = tcp_packet_chaining > 1
 #if IPSEC
-               ipsec_bypass &&
+               && ipsec_bypass
+#endif
+#if IPFIREWALL
+               && (fw_enable == 0 || fw_bypass)
 #endif
-               (fw_enable == 0 || fw_bypass);
+               ; // I'm important, not extraneous
+
 
        while (pkt != NULL) {
                struct mbuf *npkt = pkt->m_nextpkt;