vrrpd: gracefully shutdown on SIGTERM / SIGINT

Handle kill signals by gracefully destroying all of our VRRP instances.
If any of them are in Master state, send an advert with 0 priority to
notify Backup routers we are going down.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

vrrpd/vrrp.c

@@ -2354,3 +2354,21 @@ void vrrp_init(void)
 					 "VRRP virtual router hash");
 	vrf_init(NULL, NULL, NULL, NULL, NULL);
 }
+
+void vrrp_fini(void)
+{
+	/* Destroy all instances */
+	struct list *vrs = hash_to_list(vrrp_vrouters_hash);
+
+	struct listnode *ln;
+	struct vrrp_vrouter *vr;
+
+	for (ALL_LIST_ELEMENTS_RO(vrs, ln, vr)) {
+		vrrp_vrouter_destroy(vr);
+	}
+
+	list_delete(&vrs);
+
+	hash_clean(vrrp_vrouters_hash, NULL);
+	hash_free(vrrp_vrouters_hash);
+}

vrrpd/vrrp.h

@@ -265,6 +265,14 @@ struct vrrp_vrouter {
  */
 void vrrp_init(void);
 
+/*
+ * Destroy all VRRP instances and gracefully shutdown.
+ *
+ * For instances in Master state, VRRP advertisements with 0 priority will be
+ * sent if possible to notify Backup routers that we are going away.
+ */
+void vrrp_fini(void);
+
 
 /* Creation and destruction ------------------------------------------------ */
 

vrrpd/vrrp_main.c

@@ -69,10 +69,12 @@ static void sighup(void)
 }
 
 /* SIGINT / SIGTERM handler. */
-static void sigint(void)
+static void __attribute__((noreturn)) sigint(void)
 {
 	zlog_notice("Terminating on signal");
 
+	vrrp_fini();
+
 	exit(0);
 }