From a7fe36b40b19de7766981ad47d69f44c8eb1466d Mon Sep 17 00:00:00 2001
From: mpi <mpi@openbsd.org>
Date: Tue, 13 Oct 2015 10:16:17 +0000
Subject: [PATCH] Use rtisivalid(9) to check if the given (cached) route can be
 used.

Note that after calling rtalloc(9) we only check if a route has been
returned or not and do not check for its validity.  This cannot be
improved without a massive refactoring.

The kernel currently *do* use !RTF_UP route due to a mismatch between
the value of ifp->if_link_state and the IFF_UP|IFF_RUNNING code.

I'd explain the RTF_UP flag as follow:

.  If a cached route entry w/o RTF_UP is passed to ip{6,}_output(),
.  call rtalloc(9) to see if a better entry is present in the tree.

This is enough to support MPATH and route cache invalidation.

ok bluhm@
---
 sys/netinet/ip_output.c |  6 +++---
 sys/netinet6/in6_src.c  | 14 ++++++--------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 24ecc1b4bdb..11af574b2b4 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_output.c,v 1.300 2015/10/07 14:52:45 deraadt Exp $	*/
+/*	$OpenBSD: ip_output.c,v 1.301 2015/10/13 10:16:17 mpi Exp $	*/
 /*	$NetBSD: ip_output.c,v 1.28 1996/02/13 23:43:07 christos Exp $	*/
 
 /*
@@ -170,9 +170,9 @@ reroute:
 	 * If there is a cached route, check that it is to the same
 	 * destination and is still up.  If not, free it and try again.
 	 */
-	if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
+	if (!rtisvalid(ro->ro_rt) ||
 	    dst->sin_addr.s_addr != ip->ip_dst.s_addr ||
-	    ro->ro_tableid != m->m_pkthdr.ph_rtableid)) {
+	    ro->ro_tableid != m->m_pkthdr.ph_rtableid) {
 		rtfree(ro->ro_rt);
 		ro->ro_rt = NULL;
 	}
diff --git a/sys/netinet6/in6_src.c b/sys/netinet6/in6_src.c
index 8ab08e25cfb..bbb916efece 100644
--- a/sys/netinet6/in6_src.c
+++ b/sys/netinet6/in6_src.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in6_src.c,v 1.62 2015/09/18 14:26:22 mpi Exp $	*/
+/*	$OpenBSD: in6_src.c,v 1.63 2015/10/13 10:16:17 mpi Exp $	*/
 /*	$KAME: in6_src.c,v 1.36 2001/02/06 04:08:17 itojun Exp $	*/
 
 /*
@@ -252,13 +252,12 @@ in6_selectsrc(struct in6_addr **in6src, struct sockaddr_in6 *dstsock,
 	 * our src addr is taken from the i/f, else punt.
 	 */
 	if (ro) {
-		if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
-		    !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst))) {
+		if (!rtisvalid(ro->ro_rt) ||
+		    !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst)) {
 			rtfree(ro->ro_rt);
 			ro->ro_rt = NULL;
 		}
-		if (ro->ro_rt == (struct rtentry *)0 ||
-		    ro->ro_rt->rt_ifp == (struct ifnet *)0) {
+		if (ro->ro_rt == NULL) {
 			struct sockaddr_in6 *sa6;
 
 			/* No route yet, so try to acquire one */
@@ -368,10 +367,9 @@ in6_selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
 	 * cached destination, in case of sharing the cache with IPv4.
 	 */
 	if (ro) {
-		if (ro->ro_rt &&
-		    (!(ro->ro_rt->rt_flags & RTF_UP) ||
+		if (!rtisvalid(ro->ro_rt) ||
 		     sin6tosa(&ro->ro_dst)->sa_family != AF_INET6 ||
-		     !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst))) {
+		     !IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, dst)) {
 			rtfree(ro->ro_rt);
 			ro->ro_rt = NULL;
 		}
-- 
2.20.1