vrrp: Don't send IPv6 advert from interface with no address

If an interface has no IPv6 address, no advert can be sent. Rather
that logging an error when the send fails, simply don't send the
advert.

Signed-off-by: Quentin Armitage <quentin@armitage.org.uk>

keepalived/core/keepalived_netlink.c

@@ -1184,6 +1184,14 @@ netlink_if_address_filter(__attribute__((unused)) struct sockaddr_nl *snl, struc
 						  IF_ISUP(ifp)) &&
 #endif
 						 (!__test_bit(VRRP_FLAG_SADDR_FROM_CONFIG, &vrrp->flags) || is_tracking_saddr)) {
+						/* Don't attempt to send an IPv6 advert if no address on the interface */
+						if (vrrp->saddr.ss_family == AF_INET6
+#ifdef _HAVE_VRRP_VMAC_
+						    && !__test_bit(VRRP_VMAC_XMITBASE_BIT, &vrrp->flags)
+#endif
+											)
+							vrrp->saddr.ss_family = AF_UNSPEC;
+
 						down_instance(vrrp);
 						vrrp->saddr.ss_family = AF_UNSPEC;
 					}

keepalived/vrrp/vrrp.c

@@ -1814,7 +1814,10 @@ vrrp_state_leave_master(vrrp_t * vrrp, bool advF)
 	}
 	else if (vrrp->wantstate == VRRP_STATE_FAULT) {
 		log_message(LOG_INFO, "(%s) Entering FAULT STATE", vrrp->iname);
-		vrrp_send_adv(vrrp, VRRP_PRIO_STOP);
+
+		/* If there is no address on the interface we cannot sent an IPv6 advert */
+		if (vrrp->family == AF_INET || vrrp->saddr.ss_family != AF_UNSPEC)
+			vrrp_send_adv(vrrp, VRRP_PRIO_STOP);
 	}
 	else {
 		log_message(LOG_INFO, "(%s) vrrp_state_leave_master called with invalid wantstate %d", vrrp->iname, vrrp->wantstate);