D-GSM 2/n: implement mDNS method of mslookup server
Implement the mslookup server's mDNS responder, to actually service remote
mslookup requests:
- VTY mslookup/server config with service names,
- the mslookup_mdns_server listening for mslookup requests,
For a detailed overview of the D-GSM and mslookup related files, please see the
elaborate comment at the top of mslookup.c (already added in an earlier patch).
Change-Id: I5cae6459090588b4dd292be90a5e8903432669d2
diff --git a/src/mslookup_server_mdns.c b/src/mslookup_server_mdns.c
new file mode 100644
index 0000000..0e94074
--- /dev/null
+++ b/src/mslookup_server_mdns.c
@@ -0,0 +1,157 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <osmocom/mslookup/mslookup.h>
+#include <osmocom/mslookup/mdns.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/hlr/hlr.h>
+#include <osmocom/hlr/mslookup_server.h>
+#include <osmocom/hlr/mslookup_server_mdns.h>
+
+static void osmo_mslookup_server_mdns_tx(struct osmo_mslookup_server_mdns *server,
+ uint16_t packet_id,
+ const struct osmo_mslookup_query *query,
+ const struct osmo_mslookup_result *result)
+{
+ struct msgb *msg;
+ const char *errmsg = NULL;
+ void *ctx = talloc_named_const(server, 0, __func__);
+
+ msg = osmo_mdns_result_encode(ctx, packet_id, query, result, server->domain_suffix);
+ if (!msg)
+ errmsg = "Error encoding mDNS answer packet";
+ else if (osmo_mdns_sock_send(server->sock, msg))
+ errmsg = "Error sending mDNS answer";
+ if (errmsg)
+ LOGP(DMSLOOKUP, LOGL_ERROR, "%s: mDNS: %s\n", osmo_mslookup_result_name_c(ctx, query, result), errmsg);
+ talloc_free(ctx);
+}
+
+static void osmo_mslookup_server_mdns_handle_request(uint16_t packet_id,
+ struct osmo_mslookup_server_mdns *server,
+ const struct osmo_mslookup_query *query)
+{
+ struct osmo_mslookup_result result;
+
+ mslookup_server_rx(query, &result);
+ /* Error logging already happens in mslookup_server_rx() */
+ if (result.rc != OSMO_MSLOOKUP_RC_RESULT)
+ return;
+
+ osmo_mslookup_server_mdns_tx(server, packet_id, query, &result);
+}
+
+static int osmo_mslookup_server_mdns_rx(struct osmo_fd *osmo_fd, unsigned int what)
+{
+ struct osmo_mslookup_server_mdns *server = osmo_fd->data;
+ struct osmo_mslookup_query *query;
+ uint16_t packet_id;
+ int n;
+ uint8_t buffer[1024];
+ void *ctx;
+
+ /* Parse the message and print it */
+ n = read(osmo_fd->fd, buffer, sizeof(buffer));
+ if (n < 0)
+ return n;
+
+ ctx = talloc_named_const(server, 0, __func__);
+ query = osmo_mdns_query_decode(ctx, buffer, n, &packet_id, server->domain_suffix);
+ if (!query) {
+ talloc_free(ctx);
+ return -1;
+ }
+
+ osmo_mslookup_id_name_buf((char *)buffer, sizeof(buffer), &query->id);
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "mDNS rx request: %s.%s\n", query->service, buffer);
+ osmo_mslookup_server_mdns_handle_request(packet_id, server, query);
+ talloc_free(ctx);
+ return n;
+}
+
+struct osmo_mslookup_server_mdns *osmo_mslookup_server_mdns_start(void *ctx, const struct osmo_sockaddr_str *bind_addr,
+ const char *domain_suffix)
+{
+ struct osmo_mslookup_server_mdns *server = talloc_zero(ctx, struct osmo_mslookup_server_mdns);
+ OSMO_ASSERT(server);
+ *server = (struct osmo_mslookup_server_mdns){
+ .bind_addr = *bind_addr,
+ .domain_suffix = talloc_strdup(server, domain_suffix)
+ };
+
+ server->sock = osmo_mdns_sock_init(server,
+ bind_addr->ip, bind_addr->port,
+ osmo_mslookup_server_mdns_rx,
+ server, 0);
+ if (!server->sock) {
+ LOGP(DMSLOOKUP, LOGL_ERROR,
+ "mslookup mDNS server: error initializing multicast bind on " OSMO_SOCKADDR_STR_FMT "\n",
+ OSMO_SOCKADDR_STR_FMT_ARGS(bind_addr));
+ talloc_free(server);
+ return NULL;
+ }
+
+ return server;
+}
+
+void osmo_mslookup_server_mdns_stop(struct osmo_mslookup_server_mdns *server)
+{
+ if (!server)
+ return;
+ osmo_mdns_sock_cleanup(server->sock);
+ talloc_free(server);
+}
+
+void mslookup_server_mdns_config_apply()
+{
+ /* Check whether to start/stop/restart mDNS server */
+ bool should_run;
+ bool should_stop;
+
+ should_run = g_hlr->mslookup.allow_startup
+ && g_hlr->mslookup.server.enable && g_hlr->mslookup.server.mdns.enable;
+ should_stop = g_hlr->mslookup.server.mdns.running
+ && (!should_run
+ || osmo_sockaddr_str_cmp(&g_hlr->mslookup.server.mdns.bind_addr,
+ &g_hlr->mslookup.server.mdns.running->bind_addr)
+ || strcmp(g_hlr->mslookup.server.mdns.domain_suffix,
+ g_hlr->mslookup.server.mdns.running->domain_suffix));
+
+ if (should_stop) {
+ osmo_mslookup_server_mdns_stop(g_hlr->mslookup.server.mdns.running);
+ g_hlr->mslookup.server.mdns.running = NULL;
+ LOGP(DMSLOOKUP, LOGL_NOTICE, "Stopped mslookup mDNS server\n");
+ }
+
+ if (should_run && !g_hlr->mslookup.server.mdns.running) {
+ g_hlr->mslookup.server.mdns.running =
+ osmo_mslookup_server_mdns_start(g_hlr, &g_hlr->mslookup.server.mdns.bind_addr,
+ g_hlr->mslookup.server.mdns.domain_suffix);
+ if (!g_hlr->mslookup.server.mdns.running)
+ LOGP(DMSLOOKUP, LOGL_ERROR, "Failed to start mslookup mDNS server on " OSMO_SOCKADDR_STR_FMT "\n",
+ OSMO_SOCKADDR_STR_FMT_ARGS(&g_hlr->mslookup.server.mdns.bind_addr));
+ else
+ LOGP(DMSLOOKUP, LOGL_NOTICE, "Started mslookup mDNS server, receiving mDNS requests at multicast "
+ OSMO_SOCKADDR_STR_FMT "\n",
+ OSMO_SOCKADDR_STR_FMT_ARGS(&g_hlr->mslookup.server.mdns.running->bind_addr));
+ }
+}