xnu-792.6.70.tar.gz

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

diff --git a/bsd/netinet/tcp_input.c b/bsd/netinet/tcp_input.c
index e85e6aed5b5d150ba86adc7f11c4a4d2e70211a5..624b3451fb11a2f2758c826af620cec5680e2a76 100644 (file)
--- a/bsd/netinet/tcp_input.c
+++ b/bsd/netinet/tcp_input.c
@@ -144,7 +144,7 @@ static int blackhole = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
        &blackhole, 0, "Do not send RST when dropping refused connections");
 
-int tcp_delack_enabled = 1;
+int tcp_delack_enabled = 3;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, 
     &tcp_delack_enabled, 0, 
     "Delay ACK to try and piggyback it onto a data packet");
@@ -236,13 +236,17 @@ extern int fw_verbose;
  *      - 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 4 full packets per second on this socket, we're streaming acts as "1".
+ *     - if we don't meet that criteria, 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)))
+          ((thflags & TH_PUSH) == 0) && ((tp->t_flags & TF_DELACK) == 0)) || \
+        (((tcp_delack_enabled == 3) && (tp->t_flags & TF_RXWIN0SENT) == 0) && \
+          (((tp->t_rcvtime == 0) && (tp->rcv_byps > (4* tp->t_maxseg)))  || (((thflags & TH_PUSH) == 0) && ((tp->t_flags & TF_DELACK) == 0)))))
 
 
 static int tcpdropdropablreq(struct socket *head);
@@ -1166,17 +1170,22 @@ findpcb:
         * 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 (tcp_minmss && tcp_minmssoverload &&
-           tp->t_state == TCPS_ESTABLISHED && tlen > 0) {
+       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_pps > tcp_minmssoverload) {
+               /*
+                * Setting either tcp_minmssoverload or tcp_minmss to "0" disables
+                * the check. 
+                */
+                       if (tcp_minmss && tcp_minmssoverload && tp->rcv_pps > tcp_minmssoverload) {
                                if ((tp->rcv_byps / tp->rcv_pps) < tcp_minmss) {
                                        char    ipstrbuf[MAX_IPv6_STR_LEN];
                                        printf("too many small tcp packets from "
@@ -3453,6 +3462,11 @@ tcpdropdropablreq(struct socket *head)
        if (!so)
                return 0;
        
+       head->so_incqlen--;
+       head->so_qlen--;
+       TAILQ_REMOVE(&head->so_incomp, so, so_list);
+       tcp_unlock(head, 0, 0);
+
        /* Let's remove this connection from the incomplete list */
        tcp_lock(so, 1, 0);
        
@@ -3460,10 +3474,6 @@ tcpdropdropablreq(struct socket *head)
                tcp_unlock(so, 1, 0);
                return 0;
        }
-       head->so_incqlen--;
-       head->so_qlen--;
-       TAILQ_REMOVE(&head->so_incomp, so, so_list);
-       tcp_unlock(head, 0, 0);
        
        so->so_head = NULL;
        so->so_usecount--;      /* No more held by so_head */