/* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * Copyright 2017 (c) Stefan Profanter, fortiss GmbH * Copyright 2017 (c) Fraunhofer IOSB (Author: Julius Pfrommer) * Copyright 2017 (c) Thomas Stalder, Blue Time Concept SA */ #include "ua_server_internal.h" #include "ua_services.h" #if defined(UA_ENABLE_DISCOVERY) && defined(UA_ENABLE_DISCOVERY_MULTICAST) #if UA_MULTITHREADING >= 100 static void * multicastWorkerLoop(UA_Server *server) { struct timeval next_sleep = {.tv_sec = 0, .tv_usec = 0}; volatile UA_Boolean *running = &server->discoveryManager.mdnsRunning; fd_set fds; while(*running) { FD_ZERO(&fds); UA_fd_set(server->discoveryManager.mdnsSocket, &fds); select(server->discoveryManager.mdnsSocket + 1, &fds, 0, 0, &next_sleep); if(!*running) break; unsigned short retVal = mdnsd_step(server->discoveryManager.mdnsDaemon, server->discoveryManager.mdnsSocket, FD_ISSET(server->discoveryManager.mdnsSocket, &fds), true, &next_sleep); if(retVal == 1) { UA_LOG_SOCKET_ERRNO_WRAP( UA_LOG_ERROR(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not read from socket. %s", errno_str)); break; } else if (retVal == 2) { UA_LOG_SOCKET_ERRNO_WRAP( UA_LOG_DEBUG(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not write to socket. %s", errno_str)); break; } } return NULL; } static UA_StatusCode multicastListenStart(UA_Server* server) { int err = pthread_create(&server->discoveryManager.mdnsThread, NULL, (void* (*)(void*))multicastWorkerLoop, server); if(err != 0) { UA_LOG_ERROR(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not create multicast thread."); return UA_STATUSCODE_BADUNEXPECTEDERROR; } return UA_STATUSCODE_GOOD; } static UA_StatusCode multicastListenStop(UA_Server* server) { mdnsd_shutdown(server->discoveryManager.mdnsDaemon); // wake up select if (write(server->discoveryManager.mdnsSocket, "\0", 1)) { // TODO: if makes no sense here? } // TODO: move to arch? if (pthread_join(server->discoveryManager.mdnsThread, NULL)) { UA_LOG_ERROR(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not stop thread."); return UA_STATUSCODE_BADUNEXPECTEDERROR; } return UA_STATUSCODE_BADNOTIMPLEMENTED; } # endif /* UA_MULTITHREADING */ static UA_StatusCode addMdnsRecordForNetworkLayer(UA_Server *server, const UA_String *appName, const UA_ServerNetworkLayer* nl) { UA_String hostname = UA_STRING_NULL; UA_UInt16 port = 4840; UA_String path = UA_STRING_NULL; UA_StatusCode retval = UA_parseEndpointUrl(&nl->discoveryUrl, &hostname, &port, &path); if(retval != UA_STATUSCODE_GOOD) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_NETWORK, "Server url is invalid: %.*s", (int)nl->discoveryUrl.length, nl->discoveryUrl.data); return retval; } retval = UA_Discovery_addRecord(server, appName, &hostname, port, &path, UA_DISCOVERY_TCP, true, server->config.mdnsConfig.serverCapabilities, server->config.mdnsConfig.serverCapabilitiesSize, true); if(retval != UA_STATUSCODE_GOOD) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_NETWORK, "Cannot add mDNS Record: %s", UA_StatusCode_name(retval)); return retval; } return UA_STATUSCODE_GOOD; } void startMulticastDiscoveryServer(UA_Server *server) { initMulticastDiscoveryServer(&server->discoveryManager, server); UA_String *appName = &server->config.mdnsConfig.mdnsServerName; for(size_t i = 0; i < server->config.networkLayersSize; i++) addMdnsRecordForNetworkLayer(server, appName, &server->config.networkLayers[i]); /* find any other server on the net */ UA_Discovery_multicastQuery(server); #if UA_MULTITHREADING >= 100 multicastListenStart(server); # endif } void stopMulticastDiscoveryServer(UA_Server *server) { if (!server->discoveryManager.mdnsDaemon) return; for (size_t i=0; iconfig.networkLayersSize; i++) { UA_String hostname = UA_STRING_NULL; UA_String path = UA_STRING_NULL; UA_UInt16 port = 0; UA_StatusCode retval = UA_parseEndpointUrl(&server->config.networkLayers[i].discoveryUrl, &hostname, &port, &path); if (retval != UA_STATUSCODE_GOOD) continue; UA_Discovery_removeRecord(server, &server->config.mdnsConfig.mdnsServerName, &hostname, port, true); } #if UA_MULTITHREADING >= 100 multicastListenStop(server); # else // send out last package with TTL = 0 iterateMulticastDiscoveryServer(server, NULL, false); # endif } /* All filter criteria must be fulfilled in the list entry. The comparison is case * insensitive. * @returns true if the entry matches the filter. False if the filter does not match. * */ static UA_Boolean entryMatchesCapabilityFilter(size_t serverCapabilityFilterSize, UA_String *serverCapabilityFilter, serverOnNetwork_list_entry* current) { // if the entry has less capabilities defined than the filter, there's no match if (serverCapabilityFilterSize > current->serverOnNetwork.serverCapabilitiesSize) return UA_FALSE; for(size_t i = 0; i < serverCapabilityFilterSize; i++) { UA_Boolean capabilityFound = UA_FALSE; for(size_t j = 0; j < current->serverOnNetwork.serverCapabilitiesSize; j++) { if(UA_String_equal_ignorecase(&serverCapabilityFilter[i], ¤t->serverOnNetwork.serverCapabilities[j])) { capabilityFound = UA_TRUE; break; } } if (!capabilityFound) return UA_FALSE; // entry does not match capability } return UA_TRUE; } void Service_FindServersOnNetwork(UA_Server *server, UA_Session *session, const UA_FindServersOnNetworkRequest *request, UA_FindServersOnNetworkResponse *response) { UA_LOCK_ASSERT(&server->serviceMutex, 1); if (!server->config.mdnsEnabled) { response->responseHeader.serviceResult = UA_STATUSCODE_BADNOTIMPLEMENTED; return; } /* Set LastCounterResetTime */ UA_DateTime_copy(&server->discoveryManager.serverOnNetworkRecordIdLastReset, &response->lastCounterResetTime); /* Compute the max number of records to return */ UA_UInt32 recordCount = 0; if(request->startingRecordId < server->discoveryManager.serverOnNetworkRecordIdCounter) recordCount = server->discoveryManager.serverOnNetworkRecordIdCounter - request->startingRecordId; if(request->maxRecordsToReturn && recordCount > request->maxRecordsToReturn) recordCount = UA_MIN(recordCount, request->maxRecordsToReturn); if(recordCount == 0) { response->serversSize = 0; return; } /* Iterate over all records and add to filtered list */ UA_UInt32 filteredCount = 0; UA_STACKARRAY(UA_ServerOnNetwork*, filtered, recordCount); serverOnNetwork_list_entry* current; LIST_FOREACH(current, &server->discoveryManager.serverOnNetwork, pointers) { if(filteredCount >= recordCount) break; if(current->serverOnNetwork.recordId < request->startingRecordId) continue; if(!entryMatchesCapabilityFilter(request->serverCapabilityFilterSize, request->serverCapabilityFilter, current)) continue; filtered[filteredCount++] = ¤t->serverOnNetwork; } if(filteredCount == 0) return; /* Allocate the array for the response */ response->servers = (UA_ServerOnNetwork*)UA_malloc(sizeof(UA_ServerOnNetwork)*filteredCount); if(!response->servers) { response->responseHeader.serviceResult = UA_STATUSCODE_BADOUTOFMEMORY; return; } response->serversSize = filteredCount; /* Copy the server names */ for(size_t i = 0; i < filteredCount; i++) UA_ServerOnNetwork_copy(filtered[i], &response->servers[filteredCount-i-1]); } void UA_Server_updateMdnsForDiscoveryUrl(UA_Server *server, const UA_String *serverName, const UA_MdnsDiscoveryConfiguration *mdnsConfig, const UA_String *discoveryUrl, UA_Boolean isOnline, UA_Boolean updateTxt) { UA_String hostname = UA_STRING_NULL; UA_UInt16 port = 4840; UA_String path = UA_STRING_NULL; UA_StatusCode retval = UA_parseEndpointUrl(discoveryUrl, &hostname, &port, &path); if(retval != UA_STATUSCODE_GOOD) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_NETWORK, "Server url invalid: %.*s", (int)discoveryUrl->length, discoveryUrl->data); return; } if(!isOnline) { UA_StatusCode removeRetval = UA_Discovery_removeRecord(server, serverName, &hostname, port, updateTxt); if(removeRetval != UA_STATUSCODE_GOOD) UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Could not remove mDNS record for hostname %.*s.", (int)serverName->length, serverName->data); return; } UA_String *capabilities = NULL; size_t capabilitiesSize = 0; if(mdnsConfig) { capabilities = mdnsConfig->serverCapabilities; capabilitiesSize = mdnsConfig->serverCapabilitiesSize; } UA_StatusCode addRetval = UA_Discovery_addRecord(server, serverName, &hostname, port, &path, UA_DISCOVERY_TCP, updateTxt, capabilities, capabilitiesSize, false); if(addRetval != UA_STATUSCODE_GOOD) UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Could not add mDNS record for hostname %.*s.", (int)serverName->length, serverName->data); } void UA_Server_setServerOnNetworkCallback(UA_Server *server, UA_Server_serverOnNetworkCallback cb, void* data) { UA_LOCK(&server->serviceMutex); server->discoveryManager.serverOnNetworkCallback = cb; server->discoveryManager.serverOnNetworkCallbackData = data; UA_UNLOCK(&server->serviceMutex); } static void UA_Discovery_multicastConflict(char *name, int type, void *arg) { // cppcheck-suppress unreadVariable UA_Server *server = (UA_Server*) arg; UA_LOG_ERROR(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS name conflict detected: " "'%s' for type %d", name, type); } /* Create a service domain with the format [servername]-[hostname]._opcua-tcp._tcp.local. */ static void createFullServiceDomain(char *outServiceDomain, size_t maxLen, const UA_String *servername, const UA_String *hostname) { size_t hostnameLen = hostname->length; size_t servernameLen = servername->length; maxLen -= 24; /* the length we have remaining before the opc ua postfix and * the trailing zero */ /* Can we use hostname and servername with full length? */ if(hostnameLen + servernameLen + 1 > maxLen) { if(servernameLen + 2 > maxLen) { servernameLen = maxLen; hostnameLen = 0; } else { hostnameLen = maxLen - servernameLen - 1; } } size_t offset = 0; if (hostnameLen > 0) { UA_snprintf(outServiceDomain, maxLen + 1, "%.*s-%.*s", (int) servernameLen, (char *) servername->data, (int) hostnameLen, (char *) hostname->data); offset = servernameLen + hostnameLen + 1; //replace all dots with minus. Otherwise mDNS is not valid for (size_t i=servernameLen+1; idata); offset = servernameLen; } UA_snprintf(&outServiceDomain[offset], 24, "._opcua-tcp._tcp.local."); } /* Check if mDNS already has an entry for given hostname and port combination */ static UA_Boolean UA_Discovery_recordExists(UA_Server* server, const char* fullServiceDomain, unsigned short port, const UA_DiscoveryProtocol protocol) { // [servername]-[hostname]._opcua-tcp._tcp.local. 86400 IN SRV 0 5 port [hostname]. mdns_record_t *r = mdnsd_get_published(server->discoveryManager.mdnsDaemon, fullServiceDomain); while(r) { const mdns_answer_t *data = mdnsd_record_data(r); if(data->type == QTYPE_SRV && (port == 0 || data->srv.port == port)) return true; r = mdnsd_record_next(r); } return false; } static int discovery_multicastQueryAnswer(mdns_answer_t *a, void *arg) { UA_Server *server = (UA_Server*) arg; if(a->type != QTYPE_PTR) return 0; if(a->rdname == NULL) return 0; /* Skip, if we already know about this server */ UA_Boolean exists = UA_Discovery_recordExists(server, a->rdname, 0, UA_DISCOVERY_TCP); if(exists == true) return 0; if(mdnsd_has_query(server->discoveryManager.mdnsDaemon, a->rdname)) return 0; UA_LOG_DEBUG(&server->config.logger, UA_LOGCATEGORY_SERVER, "mDNS send query for: %s SRV&TXT %s", a->name, a->rdname); mdnsd_query(server->discoveryManager.mdnsDaemon, a->rdname, QTYPE_SRV, discovery_multicastQueryAnswer, server); mdnsd_query(server->discoveryManager.mdnsDaemon, a->rdname, QTYPE_TXT, discovery_multicastQueryAnswer, server); return 0; } UA_StatusCode UA_Discovery_multicastQuery(UA_Server* server) { mdnsd_query(server->discoveryManager.mdnsDaemon, "_opcua-tcp._tcp.local.", QTYPE_PTR,discovery_multicastQueryAnswer, server); return UA_STATUSCODE_GOOD; } UA_StatusCode UA_Discovery_addRecord(UA_Server *server, const UA_String *servername, const UA_String *hostname, UA_UInt16 port, const UA_String *path, const UA_DiscoveryProtocol protocol, UA_Boolean createTxt, const UA_String* capabilites, const size_t capabilitiesSize, UA_Boolean isSelf) { // we assume that the hostname is not an IP address, but a valid domain name // It is required by the OPC UA spec (see Part 12, DiscoveryURL to DNS SRV mapping) // to always use the hostname instead of the IP address if(capabilitiesSize > 0 && !capabilites) return UA_STATUSCODE_BADINVALIDARGUMENT; size_t hostnameLen = hostname->length; size_t servernameLen = servername->length; if(hostnameLen == 0 || servernameLen == 0) return UA_STATUSCODE_BADOUTOFRANGE; // use a limit for the hostname length to make sure full string fits into 63 // chars (limited by DNS spec) if(hostnameLen+servernameLen + 1 > 63) { // include dash between servername-hostname UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: Combination of hostname+servername exceeds " "maximum of 62 chars. It will be truncated."); } else if(hostnameLen > 63) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: Hostname length exceeds maximum of 63 chars. " "It will be truncated."); } if(!server->discoveryManager.mdnsMainSrvAdded) { mdns_record_t *r = mdnsd_shared(server->discoveryManager.mdnsDaemon, "_services._dns-sd._udp.local.", QTYPE_PTR, 600); mdnsd_set_host(server->discoveryManager.mdnsDaemon, r, "_opcua-tcp._tcp.local."); server->discoveryManager.mdnsMainSrvAdded = true; } // [servername]-[hostname]._opcua-tcp._tcp.local. char fullServiceDomain[63+24]; createFullServiceDomain(fullServiceDomain, 63+24, servername, hostname); UA_Boolean exists = UA_Discovery_recordExists(server, fullServiceDomain, port, protocol); if(exists == true) return UA_STATUSCODE_GOOD; UA_LOG_INFO(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: add record for domain: %s", fullServiceDomain); if (isSelf && server->discoveryManager.selfFqdnMdnsRecord.length == 0) { server->discoveryManager.selfFqdnMdnsRecord = UA_STRING_ALLOC(fullServiceDomain); if (!server->discoveryManager.selfFqdnMdnsRecord.data) return UA_STATUSCODE_BADOUTOFMEMORY; } struct serverOnNetwork_list_entry *listEntry; // The servername is servername + hostname. It is the same which we get through mDNS and therefore we need to match servername UA_StatusCode retval = UA_DiscoveryManager_addEntryToServersOnNetwork(server, fullServiceDomain, fullServiceDomain, UA_MIN(63, (servernameLen+hostnameLen)+1), &listEntry); if (retval != UA_STATUSCODE_GOOD && retval != UA_STATUSCODE_BADALREADYEXISTS) return retval; // If entry is already in list, skip initialization of capabilities and txt+srv if (retval != UA_STATUSCODE_BADALREADYEXISTS) { // if capabilitiesSize is 0, then add default cap 'NA' listEntry->serverOnNetwork.serverCapabilitiesSize = UA_MAX(1, capabilitiesSize); listEntry->serverOnNetwork.serverCapabilities = (UA_String *) UA_Array_new(listEntry->serverOnNetwork.serverCapabilitiesSize, &UA_TYPES[UA_TYPES_STRING]); if (!listEntry->serverOnNetwork.serverCapabilities) return UA_STATUSCODE_BADOUTOFMEMORY; if (capabilitiesSize == 0) { UA_String na; na.length = 2; na.data = (UA_Byte *) (uintptr_t) "NA"; UA_String_copy(&na, &listEntry->serverOnNetwork.serverCapabilities[0]); } else { for (size_t i = 0; i < capabilitiesSize; i++) { UA_String_copy(&capabilites[i], &listEntry->serverOnNetwork.serverCapabilities[i]); } } listEntry->txtSet = true; UA_STACKARRAY(char, newUrl, 10 + hostnameLen + 8 + path->length + 1); UA_snprintf(newUrl, 10 + hostnameLen + 8 + path->length + 1, "opc.tcp://%.*s:%d%s%.*s", (int) hostnameLen, hostname->data, port, path->length > 0 ? "/" : "", (int) path->length, path->data); listEntry->serverOnNetwork.discoveryUrl = UA_String_fromChars(newUrl); listEntry->srvSet = true; } // _services._dns-sd._udp.local. PTR _opcua-tcp._tcp.local // check if there is already a PTR entry for the given service. // _opcua-tcp._tcp.local. PTR [servername]-[hostname]._opcua-tcp._tcp.local. mdns_record_t *r = mdns_find_record(server->discoveryManager.mdnsDaemon, QTYPE_PTR, "_opcua-tcp._tcp.local.", fullServiceDomain); if(!r) { r = mdnsd_shared(server->discoveryManager.mdnsDaemon, "_opcua-tcp._tcp.local.", QTYPE_PTR, 600); mdnsd_set_host(server->discoveryManager.mdnsDaemon, r, fullServiceDomain); } /* The first 63 characters of the hostname (or less) */ size_t maxHostnameLen = UA_MIN(hostnameLen, 63); char localDomain[65]; memcpy(localDomain, hostname->data, maxHostnameLen); localDomain[maxHostnameLen] = '.'; localDomain[maxHostnameLen+1] = '\0'; // [servername]-[hostname]._opcua-tcp._tcp.local. 86400 IN SRV 0 5 port [hostname]. r = mdnsd_unique(server->discoveryManager.mdnsDaemon, fullServiceDomain, QTYPE_SRV, 600, UA_Discovery_multicastConflict, server); mdnsd_set_srv(server->discoveryManager.mdnsDaemon, r, 0, 0, port, localDomain); // A/AAAA record for all ip addresses. // [servername]-[hostname]._opcua-tcp._tcp.local. A [ip]. // [hostname]. A [ip]. mdns_set_address_record(server, fullServiceDomain, localDomain); // TXT record: [servername]-[hostname]._opcua-tcp._tcp.local. TXT path=/ caps=NA,DA,... UA_STACKARRAY(char, pathChars, path->length + 1); if(createTxt) { if(path->length > 0) memcpy(pathChars, path->data, path->length); pathChars[path->length] = 0; mdns_create_txt(server, fullServiceDomain, pathChars, capabilites, capabilitiesSize, UA_Discovery_multicastConflict); } return UA_STATUSCODE_GOOD; } UA_StatusCode UA_Discovery_removeRecord(UA_Server *server, const UA_String *servername, const UA_String *hostname, UA_UInt16 port, UA_Boolean removeTxt) { // use a limit for the hostname length to make sure full string fits into 63 // chars (limited by DNS spec) size_t hostnameLen = hostname->length; size_t servernameLen = servername->length; if(hostnameLen == 0 || servernameLen == 0) return UA_STATUSCODE_BADOUTOFRANGE; if(hostnameLen+servernameLen+1 > 63) { // include dash between servername-hostname UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: Combination of hostname+servername exceeds " "maximum of 62 chars. It will be truncated."); } // [servername]-[hostname]._opcua-tcp._tcp.local. char fullServiceDomain[63 + 24]; createFullServiceDomain(fullServiceDomain, 63+24, servername, hostname); UA_LOG_INFO(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: remove record for domain: %s", fullServiceDomain); UA_StatusCode retval = UA_DiscoveryManager_removeEntryFromServersOnNetwork( server, fullServiceDomain, fullServiceDomain, UA_MIN(63, (servernameLen+hostnameLen)+1)); if (retval != UA_STATUSCODE_GOOD) return retval; // _opcua-tcp._tcp.local. PTR [servername]-[hostname]._opcua-tcp._tcp.local. mdns_record_t *r = mdns_find_record(server->discoveryManager.mdnsDaemon, QTYPE_PTR, "_opcua-tcp._tcp.local.", fullServiceDomain); if(!r) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: could not remove record. " "PTR Record not found for domain: %s", fullServiceDomain); return UA_STATUSCODE_BADNOTHINGTODO; } mdnsd_done(server->discoveryManager.mdnsDaemon, r); // looks for [servername]-[hostname]._opcua-tcp._tcp.local. 86400 IN SRV 0 5 port hostname.local. // and TXT record: [servername]-[hostname]._opcua-tcp._tcp.local. TXT path=/ caps=NA,DA,... // and A record: [servername]-[hostname]._opcua-tcp._tcp.local. A [ip] mdns_record_t *r2 = mdnsd_get_published(server->discoveryManager.mdnsDaemon, fullServiceDomain); if(!r2) { UA_LOG_WARNING(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast DNS: could not remove record. Record not " "found for domain: %s", fullServiceDomain); return UA_STATUSCODE_BADNOTHINGTODO; } while(r2) { const mdns_answer_t *data = mdnsd_record_data(r2); mdns_record_t *next = mdnsd_record_next(r2); if((removeTxt && data->type == QTYPE_TXT) || (removeTxt && data->type == QTYPE_A) || data->srv.port == port) { mdnsd_done(server->discoveryManager.mdnsDaemon, r2); } r2 = next; } return UA_STATUSCODE_GOOD; } UA_StatusCode iterateMulticastDiscoveryServer(UA_Server* server, UA_DateTime *nextRepeat, UA_Boolean processIn) { struct timeval next_sleep = { 0, 0 }; unsigned short retval = mdnsd_step(server->discoveryManager.mdnsDaemon, (int)server->discoveryManager.mdnsSocket, processIn, true, &next_sleep); if(retval == 1) { UA_LOG_SOCKET_ERRNO_WRAP( UA_LOG_DEBUG(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not read from socket. %s", errno_str)); return UA_STATUSCODE_BADNOCOMMUNICATION; } else if(retval == 2) { UA_LOG_SOCKET_ERRNO_WRAP( UA_LOG_DEBUG(&server->config.logger, UA_LOGCATEGORY_SERVER, "Multicast error: Can not write to socket. %s", errno_str)); return UA_STATUSCODE_BADNOCOMMUNICATION; } if(nextRepeat) *nextRepeat = UA_DateTime_now() + (UA_DateTime)((next_sleep.tv_sec * UA_DATETIME_SEC) + (next_sleep.tv_usec * UA_DATETIME_USEC)); return UA_STATUSCODE_GOOD; } #endif /* defined(UA_ENABLE_DISCOVERY) && defined(UA_ENABLE_DISCOVERY_MULTICAST) */