From 86e85007b500fe54023f94dad0fd3f5d566fc2ba Mon Sep 17 00:00:00 2001
From: Niels Provos <provos@cvs.openbsd.org>
Date: Mon, 11 Dec 2000 19:12:23 +0000
Subject: turn off path mtu when icmp needfrag messages get blocked, okay
 itojun@

---
 sys/netinet/tcp_timer.c | 50 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 7 deletions(-)

(limited to 'sys/netinet/tcp_timer.c')

diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index 4f7b1726439..c1e08b91f27 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tcp_timer.c,v 1.17 2000/09/18 22:06:38 provos Exp $	*/
+/*	$OpenBSD: tcp_timer.c,v 1.18 2000/12/11 19:12:22 provos Exp $	*/
 /*	$NetBSD: tcp_timer.c,v 1.14 1996/02/13 23:44:09 christos Exp $	*/
 
 /*
@@ -60,6 +60,7 @@
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
 #include <netinet/tcpip.h>
+#include <netinet/ip_icmp.h>
 #include <dev/rndvar.h>
 
 int	tcp_keepidle = TCPTV_KEEP_IDLE;
@@ -236,7 +237,7 @@ tcp_timers(tp, timer)
 		    rto * tcp_backoff[tp->t_rxtshift],
 		    tp->t_rttmin, TCPTV_REXMTMAX);
 		tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
-#if 0
+
 		/* 
 		 * If we are losing and we are trying path MTU discovery,
 		 * try turning it off.  This will avoid black holes in
@@ -245,15 +246,50 @@ tcp_timers(tp, timer)
 		 * lots more sophisticated searching to find the right
 		 * value here...
 		 */
-		if (ip_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) {
+		if (ip_mtudisc && tp->t_inpcb &&
+		    tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) {
+			struct inpcb *inp = tp->t_inpcb;
 			struct rtentry *rt = NULL;
+			struct sockaddr_in sin;
 
-			if (tp->t_inpcb)
-				rt = in_pcbrtentry(tp->t_inpcb);
 
-			/* XXX:  Black hole recovery code goes here */
-		}
+			rt = in_pcbrtentry(inp);
+			/* Check if path MTU discovery is disabled already */
+			if (rt && (rt->rt_flags & RTF_HOST) &&
+			    (rt->rt_rmx.rmx_locks & RTV_MTU))
+				goto out;
+
+			rt = NULL;
+			switch(tp->pf) {
+#ifdef INET6
+			case PF_INET6:
+				/*
+				 * We can not turn off path MTU for IPv6.
+				 * Do nothing for now, maybe lower to
+				 * minimum MTU.
+				 */
+				break;
 #endif
+			case PF_INET:
+				bzero(&sin, sizeof(struct sockaddr_in));
+				sin.sin_family = AF_INET;
+				sin.sin_len = sizeof(struct sockaddr_in);
+				sin.sin_addr = inp->inp_faddr;
+				rt = icmp_mtudisc_clone(sintosa(&sin));
+				break;
+			}
+			if (rt != NULL) {
+				/* Disable path MTU discovery */
+				if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0) {
+					rt->rt_rmx.rmx_locks |= RTV_MTU;
+					in_rtchange(inp, 0);
+				}
+
+				rtfree(rt);
+			}
+			out:
+		}
+
 		/*
 		 * If losing, let the lower level know and try for
 		 * a better route.  Also, if we backed off this far,
-- 
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