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/* 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 General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdbool.h>
#include <talloc.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/select.h>
#include <osmocom/hlr/logging.h>
#include <osmocom/mslookup/mdns_sock.h>
/*! Open socket to send and receive multicast data.
*
* The socket is opened with SO_REUSEADDR, so we can bind to the same IP and port multiple times. This socket receives
* everything sent to that multicast IP/port, including its own data data sent from osmo_mdns_sock_send(). So whenever
* sending something, the receive callback will be called with the same data and should discard it.
*
* \param[in] ip multicast IPv4 or IPv6 address.
* \param[in] port port number.
* \param[in] cb callback for incoming data that will be passed to osmo_fd_setup (should read from osmo_fd->fd).
* \param[in] data userdata passed to osmo_fd (available in cb as osmo_fd->data).
* \param[in] priv_nr additional userdata integer passed to osmo_fd (available in cb as osmo_fd->priv_nr).
* \returns allocated osmo_mdns_sock, NULL on error.
*/
struct osmo_mdns_sock *osmo_mdns_sock_init(void *ctx, const char *ip, unsigned int port,
int (*cb)(struct osmo_fd *fd, unsigned int what),
void *data, unsigned int priv_nr)
{
struct osmo_mdns_sock *ret;
int sock, rc;
struct addrinfo hints = {0};
struct ip_mreq multicast_req = {0};
in_addr_t iface = INADDR_ANY;
char portbuf[10];
int y = 1;
snprintf(portbuf, sizeof(portbuf) -1, "%u", port);
ret = talloc_zero(ctx, struct osmo_mdns_sock);
OSMO_ASSERT(ret);
/* Fill addrinfo */
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = (AI_PASSIVE | AI_NUMERICHOST);
rc = getaddrinfo(ip, portbuf, &hints, &ret->ai);
if (rc != 0) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: getaddrinfo: %s\n", gai_strerror(rc));
ret->ai = NULL;
goto error;
}
/* Open socket */
sock = socket(ret->ai->ai_family, ret->ai->ai_socktype, 0);
if (sock == -1) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: socket: %s\n", strerror(errno));
goto error;
}
/* Set multicast options */
rc = setsockopt(sock, IPPROTO_IP, IP_MULTICAST_IF, (char*)&iface, sizeof(iface));
if (rc == -1) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
goto error;
}
memcpy(&multicast_req.imr_multiaddr, &((struct sockaddr_in*)(ret->ai->ai_addr))->sin_addr,
sizeof(multicast_req.imr_multiaddr));
multicast_req.imr_interface.s_addr = htonl(INADDR_ANY);
rc = setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*)&multicast_req, sizeof(multicast_req));
if (rc == -1) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
goto error;
}
/* Always allow binding the same IP and port twice. This is needed in OsmoHLR (where the code becomes cleaner by
* just using a different socket for server and client code) and in the mslookup_client_mdns_test. Also for
* osmo-mslookup-client if it is running multiple times in parallel (i.e. two incoming calls almost at the same
* time need to be resolved with the simple dialplan example that just starts new processes). */
rc = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *)&y, sizeof(y));
if (rc == -1) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
goto error;
}
/* Bind and register osmo_fd callback */
rc = bind(sock, ret->ai->ai_addr, ret->ai->ai_addrlen);
if (rc == -1) {
LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: bind: %s\n", strerror(errno));
goto error;
}
osmo_fd_setup(&ret->osmo_fd, sock, OSMO_FD_READ, cb, data, priv_nr);
if (osmo_fd_register(&ret->osmo_fd) != 0)
goto error;
return ret;
error:
if (ret->ai)
freeaddrinfo(ret->ai);
talloc_free(ret);
return NULL;
}
/*! Send msgb over mdns_sock and consume msgb.
* \returns 0 on success, -1 on error.
*/
int osmo_mdns_sock_send(const struct osmo_mdns_sock *mdns_sock, struct msgb *msg)
{
size_t len = msgb_length(msg);
int rc = sendto(mdns_sock->osmo_fd.fd, msgb_data(msg), len, 0, mdns_sock->ai->ai_addr,
mdns_sock->ai->ai_addrlen);
msgb_free(msg);
return (rc == len) ? 0 : -1;
}
/*! Tear down osmo_mdns_sock. */
void osmo_mdns_sock_cleanup(struct osmo_mdns_sock *mdns_sock)
{
osmo_fd_close(&mdns_sock->osmo_fd);
freeaddrinfo(mdns_sock->ai);
talloc_free(mdns_sock);
}
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