isisd: add debug logs to troubleshoot BFD issues

when we receive an event from BFDD and we end up throwing it away,
make sure that we log (with debug guards) the reason for this, so
we can troubleshoot issues like the one addressed by the previous
commit.

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

1 files changed, 57 insertions, 10 deletions

diff --git a/isisd/isis_bfd.c b/isisd/isis_bfd.c
index 4acdc2c2d..8386ada76 100644
--- a/isisd/isis_bfd.c
+++ b/isisd/isis_bfd.c
@@ -92,22 +92,42 @@ static bool bfd_session_same(const struct bfd_session *session, int family,
 static void bfd_adj_event(struct isis_adjacency *adj, struct prefix *dst,
 			  int new_status)
 {
-	if (!adj->bfd_session)
+	if (!adj->bfd_session) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: Ignoring update for adjacency with %s, could not find bfd session on the adjacency",
+				isis_adj_name(adj));
 		return;
+	}
 
-	if (adj->bfd_session->family != dst->family)
+	if (adj->bfd_session->family != dst->family) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: Ignoring update for adjacency with %s, address family does not match the family on the adjacency",
+				isis_adj_name(adj));
 		return;
+	}
 
 	switch (adj->bfd_session->family) {
 	case AF_INET:
 		if (!IPV4_ADDR_SAME(&adj->bfd_session->dst_ip.ipv4,
-				    &dst->u.prefix4))
+				    &dst->u.prefix4)) {
+			if (IS_DEBUG_BFD)
+				zlog_debug(
+					"ISIS-BFD: Ignoring update for adjacency with %s, IPv4 address does not match",
+					isis_adj_name(adj));
 			return;
+		}
 		break;
 	case AF_INET6:
 		if (!IPV6_ADDR_SAME(&adj->bfd_session->dst_ip.ipv6,
-				    &dst->u.prefix6))
+				    &dst->u.prefix6)) {
+			if (IS_DEBUG_BFD)
+				zlog_debug(
+					"ISIS-BFD: Ignoring update for adjacency with %s, IPv6 address does not match",
+					isis_adj_name(adj));
 			return;
+		}
 		break;
 	default:
 		flog_err(EC_LIB_DEVELOPMENT, "%s: unknown address-family: %u",
@@ -119,8 +139,13 @@ static void bfd_adj_event(struct isis_adjacency *adj, struct prefix *dst,
 
 	BFD_SET_CLIENT_STATUS(adj->bfd_session->status, new_status);
 
-	if (old_status == new_status)
+	if (old_status == new_status) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: Ignoring update for adjacency with %s, new status matches current known status",
+				isis_adj_name(adj));
 		return;
+	}
 
 	if (IS_DEBUG_BFD) {
 		char dst_str[INET6_ADDRSTRLEN];
@@ -166,8 +191,12 @@ static int isis_bfd_interface_dest_update(ZAPI_CALLBACK_ARGS)
 
 	struct isis_circuit *circuit = circuit_scan_by_ifp(ifp);
 
-	if (!circuit)
+	if (!circuit) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: Ignoring update, could not find circuit");
 		return 0;
+	}
 
 	if (circuit->circ_type == CIRCUIT_T_BROADCAST) {
 		for (int level = ISIS_LEVEL1; level <= ISIS_LEVEL2; level++) {
@@ -326,8 +355,13 @@ static void bfd_handle_adj_up(struct isis_adjacency *adj, int command)
 	struct list *local_ips;
 	struct prefix *local_ip;
 
-	if (!circuit->bfd_info)
+	if (!circuit->bfd_info) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: skipping BFD initialization on adjacency with %s because there is no bfd_info in the circuit",
+				isis_adj_name(adj));
 		goto out;
+	}
 
 	/* If IS-IS IPv6 is configured wait for IPv6 address to be programmed
 	 * before starting up BFD
@@ -350,16 +384,24 @@ static void bfd_handle_adj_up(struct isis_adjacency *adj, int command)
 		family = AF_INET6;
 		dst_ip.ipv6 = adj->ipv6_addresses[0];
 		local_ips = circuit->ipv6_link;
-		if (!local_ips || list_isempty(local_ips))
+		if (!local_ips || list_isempty(local_ips)) {
+			if (IS_DEBUG_BFD)
+				zlog_debug(
+					"ISIS-BFD: skipping BFD initialization: IPv6 enabled and no local IPv6 addresses");
 			goto out;
+		}
 		local_ip = listgetdata(listhead(local_ips));
 		src_ip.ipv6 = local_ip->u.prefix6;
 	} else if (circuit->ip_router && adj->ipv4_address_count) {
 		family = AF_INET;
 		dst_ip.ipv4 = adj->ipv4_addresses[0];
 		local_ips = fabricd_ip_addrs(adj->circuit);
-		if (!local_ips || list_isempty(local_ips))
+		if (!local_ips || list_isempty(local_ips)) {
+			if (IS_DEBUG_BFD)
+				zlog_debug(
+					"ISIS-BFD: skipping BFD initialization: IPv4 enabled and no local IPv4 addresses");
 			goto out;
+		}
 		local_ip = listgetdata(listhead(local_ips));
 		src_ip.ipv4 = local_ip->u.prefix4;
 	} else
@@ -371,8 +413,13 @@ static void bfd_handle_adj_up(struct isis_adjacency *adj, int command)
 			bfd_handle_adj_down(adj);
 	}
 
-	if (!adj->bfd_session)
+	if (!adj->bfd_session) {
+		if (IS_DEBUG_BFD)
+			zlog_debug(
+				"ISIS-BFD: creating BFD session for adjacency with %s",
+				isis_adj_name(adj));
 		adj->bfd_session = bfd_session_new(family, &dst_ip, &src_ip);
+	}
 
 	bfd_debug(adj->bfd_session->family, &adj->bfd_session->dst_ip,
 		  &adj->bfd_session->src_ip, circuit->interface->name, command);