Fix nexthop lookup for connected routes.

In knexthop_true_nexthop() connected routes need to be handled specially.
If a nexthop is directly reachable the gateway needs to remain the same.
There is no nexthop set for F_CONNECTED kroutes. A very similar trick
is used in rde_rib.c::nexthop_update() but was forgotten here.

Regression noticed by Daniel Jakots (danj at chown.me).
OK tb@

diff --git a/usr.sbin/bgpd/kroute.c b/usr.sbin/bgpd/kroute.c
index 8c55e80..b7778fb 100644 (file)
--- a/usr.sbin/bgpd/kroute.c
+++ b/usr.sbin/bgpd/kroute.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kroute.c,v 1.294 2022/08/18 17:02:42 claudio Exp $ */
+/*     $OpenBSD: kroute.c,v 1.295 2022/08/19 09:11:18 claudio Exp $ */
 
 /*
  * Copyright (c) 2022 Claudio Jeker <claudio@openbsd.org>
@@ -2152,11 +2152,15 @@ knexthop_true_nexthop(struct ktable *kt, struct kroute_full *kf)
        switch (kn->nexthop.aid) {
        case AID_INET:
                kr = kn->kroute;
+               if (kr->flags & F_CONNECTED)
+                       return 1;
                gateway.aid = AID_INET;
                gateway.v4.s_addr = kr->nexthop.s_addr;
                break;
        case AID_INET6:
                kr6 = kn->kroute;
+               if (kr6->flags & F_CONNECTED)
+                       return 1;
                gateway.aid = AID_INET6;
                gateway.v6 = kr6->nexthop;
                gateway.scope_id = kr6->nexthop_scope_id;