nhrpd: shortcut routes installed with nexthop.

Previously, when a shortcut entry was created, its associated route was
created on system, with no nexthop, only gre device. eg:

[..]
N>* 192.168.2.0/24 [10/0] is directly connected, gre1, 00:01:04           <--- can not be resolved

[..]
Type     Prefix                   Via                      Identity
dynamic  192.168.2.0/24           10.255.255.2             				<---- correct

This situation was forcing neighbor resolution on the first outgoing packet matching the route entry. for instance 192.168.2.1 could not be resolved at link layer, and was going to fail. Instead, nhrp nexthop should have been used.
This is what this commit intends to do, that is to say that when a
shortcut is installed by nhrp, the associated nexthop entry is used.

[..]
N>* 192.168.2.0/24 [10/0] via 10.255.255.2, gre1 onlink, 00:00:31

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/nhrpd/nhrp_shortcut.c b/nhrpd/nhrp_shortcut.c
index 6ad0c9ea03..fbb883185a 100644
--- a/nhrpd/nhrp_shortcut.c
+++ b/nhrpd/nhrp_shortcut.c
@@ -51,18 +51,26 @@ static int nhrp_shortcut_do_expire(struct thread *t)
 static void nhrp_shortcut_cache_notify(struct notifier_block *n,
 				       unsigned long cmd)
 {
+	char buf2[PREFIX_STRLEN];
+
 	struct nhrp_shortcut *s =
 		container_of(n, struct nhrp_shortcut, cache_notifier);
+	struct nhrp_cache *c = s->cache;
 
+	if (c)
+		sockunion2str(&c->remote_addr, buf2, sizeof(buf2));
+	else
+		snprintf(buf2, sizeof(buf2), "(unspec)");
 	switch (cmd) {
 	case NOTIFY_CACHE_UP:
 		if (!s->route_installed) {
 			debugf(NHRP_DEBUG_ROUTE,
-			       "Shortcut: route install %pFX nh (unspec) dev %s",
-			       s->p, s->cache->ifp->name);
+			       "Shortcut: route install %pFX nh %s dev %s",
+			       s->p, buf2, c && c->ifp ?
+			       c->ifp->name : "<unk>");
 
-			nhrp_route_announce(1, s->type, s->p, s->cache->ifp,
-					    &s->cache->remote_addr, 0);
+			nhrp_route_announce(1, s->type, s->p, c ? c->ifp : NULL,
+					    c ? &c->remote_addr : NULL, 0);
 			s->route_installed = 1;
 		}
 		break;