Reevaluate received mappings upon receipt of address message.

If a neighbor was a nexthop for a given set of prefixes but it's not
anymore, then we should uninstall the associated label mappings (if any)
from the kernel.  The same applies for the other way round (neighbor
wasn't a nexthop for a given set of prefixes but now is).

This issue is only evident when we have multiple links between a pair
of LSRs. Generally, when a link is shut down, the whole LDP is torn down
and all label mappings uninstalled automatically.

ok claudio@

1 files changed, 50 insertions, 1 deletions

diff --git a/usr.sbin/ldpd/lde.c b/usr.sbin/ldpd/lde.c
index 84f5565941a..2985cac573b 100644
--- a/usr.sbin/ldpd/lde.c
+++ b/usr.sbin/ldpd/lde.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: lde.c,v 1.65 2016/09/02 17:03:24 renato Exp $ */
+/*	$OpenBSD: lde.c,v 1.66 2016/09/02 17:05:23 renato Exp $ */
 
 /*
  * Copyright (c) 2013, 2016 Renato Westphal <renato@openbsd.org>
@@ -50,6 +50,8 @@ static struct lde_nbr	*lde_nbr_new(uint32_t, struct lde_nbr *);
 static void		 lde_nbr_del(struct lde_nbr *);
 static struct lde_nbr	*lde_nbr_find(uint32_t);
 static void		 lde_nbr_clear(void);
+static void		 lde_nbr_addr_update(struct lde_nbr *,
+			    struct lde_addr *, int);
 static void		 lde_map_free(void *);
 static int		 lde_address_add(struct lde_nbr *, struct lde_addr *);
 static int		 lde_address_del(struct lde_nbr *, struct lde_addr *);
@@ -1077,6 +1079,47 @@ lde_nbr_clear(void)
 		lde_nbr_del(ln);
 }
 
+static void
+lde_nbr_addr_update(struct lde_nbr *ln, struct lde_addr *lde_addr, int removed)
+{
+	struct fec		*fec;
+	struct fec_node		*fn;
+	struct fec_nh		*fnh;
+	struct lde_map		*me;
+
+	RB_FOREACH(fec, fec_tree, &ln->recv_map) {
+		fn = (struct fec_node *)fec_find(&ft, fec);
+		switch (fec->type) {
+		case FEC_TYPE_IPV4:
+			if (lde_addr->af != AF_INET)
+				continue;
+			break;
+		case FEC_TYPE_IPV6:
+			if (lde_addr->af != AF_INET6)
+				continue;
+			break;
+		default:
+			continue;
+		}
+
+		LIST_FOREACH(fnh, &fn->nexthops, entry) {
+			if (ldp_addrcmp(fnh->af, &fnh->nexthop,
+			    &lde_addr->addr))
+				continue;
+
+			if (removed) {
+				lde_send_delete_klabel(fn, fnh);
+				fnh->remote_label = NO_LABEL;
+			} else {
+				me = (struct lde_map *)fec;
+				fnh->remote_label = me->map.label;
+				lde_send_change_klabel(fn, fnh);
+			}
+			break;
+		}
+	}
+}
+
 struct lde_map *
 lde_map_add(struct lde_nbr *ln, struct fec_node *fn, int sent)
 {
@@ -1248,6 +1291,9 @@ lde_address_add(struct lde_nbr *ln, struct lde_addr *lde_addr)
 	new->addr = lde_addr->addr;
 	TAILQ_INSERT_TAIL(&ln->addr_list, new, entry);
 
+	/* reevaluate the previously received mappings from this neighbor */
+	lde_nbr_addr_update(ln, lde_addr, 0);
+
 	return (0);
 }
 
@@ -1258,6 +1304,9 @@ lde_address_del(struct lde_nbr *ln, struct lde_addr *lde_addr)
 	if (lde_addr == NULL)
 		return (-1);
 
+	/* reevaluate the previously received mappings from this neighbor */
+	lde_nbr_addr_update(ln, lde_addr, 1);
+
 	TAILQ_REMOVE(&ln->addr_list, lde_addr, entry);
 	free(lde_addr);