isisd, ospfd: IGPs detect LDP down via zapi client close message

When ldp-sync is configured, IGPs take action if the LDP process goes down.

Currently, IGPs detect the LDP process is down if they do not receive a
periodic 'hello' message from LDP within 1 second.

Intermittently, this heartbeat mechanism causes false topotest failures.
When the failure occurs, LDP is busy receiving messages from zebra for a
few seconds.  During this time, LDP does not send the expected periodic
message.

With this change, IGPs detect LDP down via zapi client close message.

Signed-off-by: Karen Schoener <karen@voltanet.io>

1 files changed, 28 insertions, 1 deletions

diff --git a/ospfd/ospf_ldp_sync.c b/ospfd/ospf_ldp_sync.c
index 68792ebcc..bca15304b 100644
--- a/ospfd/ospf_ldp_sync.c
+++ b/ospfd/ospf_ldp_sync.c
@@ -253,6 +253,33 @@ void ospf_ldp_sync_if_complete(struct interface *ifp)
 	}
 }
 
+void ospf_ldp_sync_handle_client_close(struct zapi_client_close_info *info)
+{
+	struct ospf *ospf;
+	struct vrf *vrf;
+	struct interface *ifp;
+
+	/* if ospf is not enabled or LDP-SYNC is not configured ignore */
+	ospf = ospf_lookup_by_vrf_id(VRF_DEFAULT);
+	if (ospf == NULL
+	    || !CHECK_FLAG(ospf->ldp_sync_cmd.flags, LDP_SYNC_FLAG_ENABLE))
+		return;
+
+	/* Check if the LDP main client session closed */
+	if (info->proto != ZEBRA_ROUTE_LDP || info->session_id == 0)
+		return;
+
+	/* Handle the zebra notification that the LDP client session closed.
+	 *  set cost to LSInfinity
+	 *  send request to LDP for LDP-SYNC state for each interface
+	 */
+	zlog_err("ldp_sync: LDP down");
+
+	vrf = vrf_lookup_by_id(ospf->vrf_id);
+	FOR_ALL_INTERFACES (vrf, ifp)
+		ospf_ldp_sync_if_start(ifp, true);
+}
+
 void ospf_ldp_sync_ldp_fail(struct interface *ifp)
 {
 	struct ospf_if_params *params;
@@ -264,7 +291,7 @@ void ospf_ldp_sync_ldp_fail(struct interface *ifp)
 	params = IF_DEF_PARAMS(ifp);
 	ldp_sync_info = params->ldp_sync_info;
 
-	/* LDP failed to send hello:
+	/* LDP client close detected:
 	 *  stop holddown timer
 	 *  set cost of interface to LSInfinity so traffic will use different
 	 *  interface until LDP has learned all labels from peer