236 lines
7.5 KiB
C
236 lines
7.5 KiB
C
/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netdb.h>
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#include <unistd.h>
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#include <errno.h>
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#include <osmocom/core/select.h>
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#include <osmocom/gsm/gsm_utils.h>
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#include <osmocom/hlr/logging.h>
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#include <osmocom/mslookup/mdns.h>
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#include <osmocom/mslookup/mdns_sock.h>
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#include <osmocom/mslookup/mslookup_client.h>
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#include <osmocom/mslookup/mslookup_client_mdns.h>
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struct osmo_mdns_method_state {
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/* Parameters passed by _add_method_dns() */
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struct osmo_sockaddr_str bind_addr;
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const char *domain_suffix;
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struct osmo_mdns_sock *mc;
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struct osmo_mslookup_client *client;
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struct llist_head requests;
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uint16_t next_packet_id;
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};
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struct osmo_mdns_method_request {
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struct llist_head entry;
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uint32_t request_handle;
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struct osmo_mslookup_query query;
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uint16_t packet_id;
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};
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static int request_handle_by_query(uint32_t *request_handle, struct osmo_mdns_method_state *state,
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struct osmo_mslookup_query *query, uint16_t packet_id)
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{
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struct osmo_mdns_method_request *request;
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llist_for_each_entry(request, &state->requests, entry) {
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if (strcmp(request->query.service, query->service) != 0)
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continue;
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if (osmo_mslookup_id_cmp(&request->query.id, &query->id) != 0)
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continue;
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/* Match! */
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*request_handle = request->request_handle;
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return 0;
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}
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return -1;
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}
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static int mdns_method_recv(struct osmo_fd *osmo_fd, unsigned int what)
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{
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struct osmo_mdns_method_state *state = osmo_fd->data;
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struct osmo_mslookup_result result;
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struct osmo_mslookup_query query;
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uint16_t packet_id;
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int n;
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uint8_t buffer[1024];
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uint32_t request_handle = 0;
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void *ctx = state;
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n = read(osmo_fd->fd, buffer, sizeof(buffer));
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if (n < 0) {
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LOGP(DMSLOOKUP, LOGL_ERROR, "failed to read from socket\n");
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return n;
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}
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if (osmo_mdns_result_decode(ctx, buffer, n, &packet_id, &query, &result, state->domain_suffix) < 0)
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return -EINVAL;
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if (request_handle_by_query(&request_handle, state, &query, packet_id) != 0)
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return -EINVAL;
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osmo_mslookup_client_rx_result(state->client, request_handle, &result);
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return n;
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}
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static void mdns_method_request(struct osmo_mslookup_client_method *method, const struct osmo_mslookup_query *query,
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uint32_t request_handle)
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{
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char buf[256];
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struct osmo_mdns_method_state *state = method->priv;
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struct msgb *msg;
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struct osmo_mdns_method_request *r = talloc_zero(method->client, struct osmo_mdns_method_request);
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*r = (struct osmo_mdns_method_request){
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.request_handle = request_handle,
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.query = *query,
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.packet_id = state->next_packet_id,
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};
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llist_add(&r->entry, &state->requests);
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state->next_packet_id++;
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msg = osmo_mdns_query_encode(method->client, r->packet_id, query, state->domain_suffix);
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if (!msg) {
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LOGP(DMSLOOKUP, LOGL_ERROR, "Cannot encode request: %s\n",
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osmo_mslookup_result_name_b(buf, sizeof(buf), query, NULL));
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}
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/* Send over the wire */
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LOGP(DMSLOOKUP, LOGL_DEBUG, "sending mDNS query: %s.%s\n", query->service,
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osmo_mslookup_id_name_b(buf, sizeof(buf), &query->id));
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if (osmo_mdns_sock_send(state->mc, msg) == -1)
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LOGP(DMSLOOKUP, LOGL_ERROR, "sending mDNS query failed\n");
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}
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static void mdns_method_request_cleanup(struct osmo_mslookup_client_method *method, uint32_t request_handle)
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{
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struct osmo_mdns_method_state *state = method->priv;
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/* Tear down any state associated with this handle. */
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struct osmo_mdns_method_request *r;
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llist_for_each_entry(r, &state->requests, entry) {
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if (r->request_handle != request_handle)
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continue;
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llist_del(&r->entry);
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talloc_free(r);
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return;
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}
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}
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static void mdns_method_destruct(struct osmo_mslookup_client_method *method)
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{
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struct osmo_mdns_method_state *state = method->priv;
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struct osmo_mdns_method_request *e, *n;
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if (!state)
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return;
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/* Drop all DNS lookup request state. Triggering a timeout event and cleanup for mslookup client users will
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* happen in the mslookup_client.c, we will simply stop responding from this lookup method. */
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llist_for_each_entry_safe(e, n, &state->requests, entry) {
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llist_del(&e->entry);
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}
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osmo_mdns_sock_cleanup(state->mc);
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}
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/*! Initialize the mDNS lookup method.
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* \param[in] client the client to attach the method to.
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* \param[in] ip IPv4 or IPv6 address string.
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* \param[in] port The port to bind to.
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* \param[in] initial_packet_id Used in the first mslookup query, then increased by one in each following query. All
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* servers answer to each query with the same packet ID. Set to -1 to use a random
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* initial ID (recommended unless you need deterministic output). This ID is for visually
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* distinguishing the packets in packet sniffers, the mslookup client uses not just the
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* ID, but all query parameters (service type, ID, ID type), to determine if a reply is
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* relevant.
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* \param[in] domain_suffix is appended to each domain in the queries to avoid colliding with the top-level domains
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* administrated by IANA. Example: "mdns.osmocom.org" */
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struct osmo_mslookup_client_method *osmo_mslookup_client_add_mdns(struct osmo_mslookup_client *client, const char *ip,
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uint16_t port, int initial_packet_id,
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const char *domain_suffix)
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{
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struct osmo_mdns_method_state *state;
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struct osmo_mslookup_client_method *m;
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m = talloc_zero(client, struct osmo_mslookup_client_method);
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OSMO_ASSERT(m);
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state = talloc_zero(m, struct osmo_mdns_method_state);
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OSMO_ASSERT(state);
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INIT_LLIST_HEAD(&state->requests);
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if (osmo_sockaddr_str_from_str(&state->bind_addr, ip, port)) {
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LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: invalid address/port: %s %u\n",
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ip, port);
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goto error_cleanup;
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}
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if (initial_packet_id == -1) {
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if (osmo_get_rand_id((uint8_t *)&state->next_packet_id, 2) < 0) {
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LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: failed to generate random initial packet ID\n");
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goto error_cleanup;
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}
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} else
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state->next_packet_id = initial_packet_id;
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state->client = client;
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state->domain_suffix = domain_suffix;
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state->mc = osmo_mdns_sock_init(state, ip, port, mdns_method_recv, state, 0);
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if (!state->mc)
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goto error_cleanup;
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*m = (struct osmo_mslookup_client_method){
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.name = "mDNS",
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.priv = state,
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.request = mdns_method_request,
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.request_cleanup = mdns_method_request_cleanup,
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.destruct = mdns_method_destruct,
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};
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osmo_mslookup_client_method_add(client, m);
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return m;
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error_cleanup:
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talloc_free(m);
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return NULL;
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}
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const struct osmo_sockaddr_str *osmo_mslookup_client_method_mdns_get_bind_addr(struct osmo_mslookup_client_method *dns_method)
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{
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struct osmo_mdns_method_state *state;
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if (!dns_method || !dns_method->priv)
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return NULL;
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state = dns_method->priv;
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return &state->bind_addr;
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}
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const char *osmo_mslookup_client_method_mdns_get_domain_suffix(struct osmo_mslookup_client_method *dns_method)
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{
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struct osmo_mdns_method_state *state;
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if (!dns_method || !dns_method->priv)
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return NULL;
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state = dns_method->priv;
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return state->domain_suffix;
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}
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