TCP Persist handling; from 4.4BSD Lite2 (via NetBSD PR 2335)

diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index 600f6ba..d4192de 100644 (file)
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tcp_output.c,v 1.3 1996/03/14 08:06:57 tholo Exp $    */
+/*     $OpenBSD: tcp_output.c,v 1.4 1996/09/12 06:19:56 tholo Exp $    */
 /*     $NetBSD: tcp_output.c,v 1.14 1996/02/13 23:43:53 christos Exp $ */
 
 /*
@@ -154,15 +154,18 @@ again:
                 * but we haven't been called to retransmit,
                 * len will be -1.  Otherwise, window shrank
                 * after we sent into it.  If window shrank to 0,
-                * cancel pending retransmit and pull snd_nxt
-                * back to (closed) window.  We will enter persist
-                * state below.  If the window didn't close completely,
-                * just wait for an ACK.
+                * calcel pending retransmit, pull snd_nxt back
+                * to (closed) window, and set the persist timer
+                * if it isn't already running.  If the window
+                * didn't close completely, just wait for an ACK.
                 */
                len = 0;
                if (win == 0) {
                        tp->t_timer[TCPT_REXMT] = 0;
+                       tp->t_rxtshift = 0;
                        tp->snd_nxt = tp->snd_una;
+                       if (tp->t_timer[TCPT_PERSIST] == 0)
+                               tcp_setpersist(tp);
                }
        }
        if (len > tp->t_maxseg) {

diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index dd075c0..14e8d42 100644 (file)
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tcp_timer.c,v 1.5 1996/07/29 22:01:51 niklas Exp $    */
+/*     $OpenBSD: tcp_timer.c,v 1.6 1996/09/12 06:19:57 tholo Exp $     */
 /*     $NetBSD: tcp_timer.c,v 1.14 1996/02/13 23:44:09 christos Exp $  */
 
 /*
@@ -63,6 +63,7 @@
 
 int    tcp_keepidle = TCPTV_KEEP_IDLE;
 int    tcp_keepintvl = TCPTV_KEEPINTVL;
+int    tcp_maxpersistidle = TCPTV_KEEP_IDLE;   /* max idle time in persist */
 int    tcp_maxidle;
 #endif /* TUBA_INCLUDE */
 /*
@@ -165,6 +166,8 @@ tcp_canceltimers(tp)
 int    tcp_backoff[TCP_MAXRXTSHIFT + 1] =
     { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
 
+int tcp_totbackoff = 511;      /* sum of tcp_backoff[] */
+
 /*
  * TCP timer processing.
  */
@@ -268,6 +271,20 @@ tcp_timers(tp, timer)
         */
        case TCPT_PERSIST:
                tcpstat.tcps_persisttimeo++;
+               /*
+                * Hack: if the peer is dead/unreachable, we do not
+                * time out if the window is closed.  After a full
+                * backoff, drop the connection if the idle time
+                * (no responses to probes) reaches the maximum
+                * backoff that we would use if retransmitting.
+                */
+               if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
+                   (tp->t_idle >= tcp_maxpersistidle ||
+                    tp->t_idle >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
+                       tcpstat.tcps_persistdrop++;
+                       tp = tcp_drop(tp, ETIMEDOUT);
+                       break;
+               }
                tcp_setpersist(tp);
                tp->t_force = 1;
                (void) tcp_output(tp);

diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index ecae9f2..dde7c1b 100644 (file)
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tcp_var.h,v 1.3 1996/03/03 22:30:50 niklas Exp $      */
+/*     $OpenBSD: tcp_var.h,v 1.4 1996/09/12 06:19:57 tholo Exp $       */
 /*     $NetBSD: tcp_var.h,v 1.17 1996/02/13 23:44:24 christos Exp $    */
 
 /*
@@ -181,6 +181,7 @@ struct      tcpstat {
        u_long  tcps_timeoutdrop;       /* conn. dropped in rxmt timeout */
        u_long  tcps_rexmttimeo;        /* retransmit timeouts */
        u_long  tcps_persisttimeo;      /* persist timeouts */
+       u_long  tcps_persistdrop;       /* connections dropped in persist */
        u_long  tcps_keeptimeo;         /* keepalive timeouts */
        u_long  tcps_keepprobe;         /* keepalive probes sent */
        u_long  tcps_keepdrops;         /* connections dropped in keepalive */