From: tholo <tholo@openbsd.org>
Date: Thu, 12 Sep 1996 06:19:56 +0000 (+0000)
Subject: TCP Persist handling; from 4.4BSD Lite2 (via NetBSD PR 2335)
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=db011c5bc0920cb435c571d01c766f4612755593;p=openbsd

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 600f6bad8d5..d4192defcd5 100644
--- 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 dd075c0d120..14e8d42ca7b 100644
--- 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 ecae9f2469d..dde7c1b1e77 100644
--- 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 */