Stack: Only allow to call FindServersOnNetwork if mDNS is enabled

src/server/ua_services_discovery_multicast.c

@@ -154,6 +154,11 @@ filterServerRecord(size_t serverCapabilityFilterSize, UA_String *serverCapabilit
 void Service_FindServersOnNetwork(UA_Server *server, UA_Session *session,
                                   const UA_FindServersOnNetworkRequest *request,
                                   UA_FindServersOnNetworkResponse *response) {
+	if (!server->config.discovery.mdnsEnable) {
+		response->responseHeader.serviceResult = UA_STATUSCODE_BADNOTIMPLEMENTED;
+		return;
+	}
+
     /* Set LastCounterResetTime */
     UA_DateTime_copy(&server->discoveryManager.serverOnNetworkRecordIdLastReset,
                      &response->lastCounterResetTime);