isisd: fix BFD session when IPv6 not configured

A wrong check was silently skipping the initialization of the bfd_session
struct in the adjacency if the router was not configured for IPv6. This
would cause BFD events to be ignored regardless of the configuration.

Also add a function to return the "name" of an adjacency and use it in a
couple of places, including the new log, instead of repeating the same
code in a bunch of places.

Signed-off-by: Emanuele Di Pascale <emanuele@voltanet.io>

3 files changed, 22 insertions, 15 deletions

diff --git a/isisd/isis_adjacency.c b/isisd/isis_adjacency.c
index 3c3a68764..744f5761c 100644
--- a/isisd/isis_adjacency.c
+++ b/isisd/isis_adjacency.c
@@ -260,22 +260,26 @@ void isis_adj_process_threeway(struct isis_adjacency *adj,
 
 	adj->threeway_state = next_tw_state;
 }
-void isis_log_adj_change(struct isis_adjacency *adj,
-			 enum isis_adj_state old_state,
-			 enum isis_adj_state new_state, const char *reason)
+const char *isis_adj_name(const struct isis_adjacency *adj)
 {
-	const char *adj_name;
+	if (!adj)
+		return "NONE";
+
 	struct isis_dynhn *dyn;
 
 	dyn = dynhn_find_by_id(adj->sysid);
 	if (dyn)
-		adj_name = dyn->hostname;
+		return dyn->hostname;
 	else
-		adj_name = sysid_print(adj->sysid);
-
+		return sysid_print(adj->sysid);
+}
+void isis_log_adj_change(struct isis_adjacency *adj,
+			 enum isis_adj_state old_state,
+			 enum isis_adj_state new_state, const char *reason)
+{
 	zlog_info(
 		"%%ADJCHANGE: Adjacency to %s (%s) for %s changed from %s to %s, %s",
-		adj_name, adj->circuit->interface->name,
+		isis_adj_name(adj), adj->circuit->interface->name,
 		adj_level2string(adj->level), adj_state2string(old_state),
 		adj_state2string(new_state), reason ? reason : "unspecified");
 }
@@ -462,11 +466,7 @@ void isis_adj_print_vty(struct isis_adjacency *adj, struct vty *vty,
 	struct isis_dynhn *dyn;
 	int level;
 
-	dyn = dynhn_find_by_id(adj->sysid);
-	if (dyn)
-		vty_out(vty, "  %-20s", dyn->hostname);
-	else
-		vty_out(vty, "  %-20s", sysid_print(adj->sysid));
+	vty_out(vty, " %-20s", isis_adj_name(adj));
 
 	if (detail == ISIS_UI_LEVEL_BRIEF) {
 		if (adj->circuit)
diff --git a/isisd/isis_adjacency.h b/isisd/isis_adjacency.h
index 3afb7209f..b517a8e03 100644
--- a/isisd/isis_adjacency.h
+++ b/isisd/isis_adjacency.h
@@ -142,5 +142,6 @@ void isis_adj_build_neigh_list(struct list *adjdb, struct list *list);
 void isis_adj_build_up_list(struct list *adjdb, struct list *list);
 int isis_adj_usage2levels(enum isis_adj_usage usage);
 int isis_bfd_startup_timer(struct thread *thread);
+const char *isis_adj_name(const struct isis_adjacency *adj);
 
 #endif /* ISIS_ADJACENCY_H */
diff --git a/isisd/isis_bfd.c b/isisd/isis_bfd.c
index 4fac73511..4acdc2c2d 100644
--- a/isisd/isis_bfd.c
+++ b/isisd/isis_bfd.c
@@ -332,9 +332,15 @@ static void bfd_handle_adj_up(struct isis_adjacency *adj, int command)
 	/* If IS-IS IPv6 is configured wait for IPv6 address to be programmed
 	 * before starting up BFD
 	 */
-	if ((circuit->ipv6_router && listcount(circuit->ipv6_link) == 0)
-	    || adj->ipv6_address_count == 0)
+	if (circuit->ipv6_router
+	    && (listcount(circuit->ipv6_link) == 0
+		|| adj->ipv6_address_count == 0)) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: skipping BFD initialization on adjacency with %s because IPv6 is enabled but not ready",
+				isis_adj_name(adj));
 		return;
+	}
 
 	/*
 	 * If IS-IS is enabled for both IPv4 and IPv6 on the circuit, prefer