Use rtalloc(9) instead of ifa_ifwithnet() to find an interface

when adding a route to gateway to ensure a most specific match.

This makes "# route add"  coherent to "# route get" even with
p2p interfaces.  Fix a problem reported by Mart Tõnso.

This also fix rttest20 after the introduction of RTF_CACHED.

ok vgross@

1 files changed, 8 insertions, 12 deletions

diff --git a/sys/net/route.c b/sys/net/route.c
index eed062d2b42..bfa5925e1da 100644
--- a/sys/net/route.c
+++ b/sys/net/route.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: route.c,v 1.316 2016/08/22 16:01:52 mpi Exp $	*/
+/*	$OpenBSD: route.c,v 1.317 2016/08/22 16:53:59 mpi Exp $	*/
 /*	$NetBSD: route.c,v 1.14 1996/02/13 22:00:46 christos Exp $	*/
 
 /*
@@ -797,20 +797,16 @@ ifa_ifwithroute(int flags, struct sockaddr *dst, struct sockaddr *gateway,
 				ifa = ifaof_ifpforaddr(dst, ifp);
 			if_put(ifp);
 		} else {
-			ifa = ifa_ifwithnet(gateway, rtableid);
-		}
-	}
-	if (ifa == NULL) {
-		struct rtentry	*rt = rtalloc(gateway, 0, rtableid);
-		/* The gateway must be local if the same address family. */
-		if (!rtisvalid(rt) || ((rt->rt_flags & RTF_GATEWAY) &&
-		    rt_key(rt)->sa_family == dst->sa_family)) {
+			struct rtentry *rt;
+
+			rt = rtalloc(gateway, RT_RESOLVE, rtableid);
+			if (rt != NULL)
+				ifa = rt->rt_ifa;
 			rtfree(rt);
-			return (NULL);
 		}
-		ifa = rt->rt_ifa;
-		rtfree(rt);
 	}
+	if (ifa == NULL)
+		return (NULL);
 	if (ifa->ifa_addr->sa_family != dst->sa_family) {
 		struct ifaddr	*oifa = ifa;
 		ifa = ifaof_ifpforaddr(dst, ifa->ifa_ifp);