diff options
Diffstat (limited to 'src/mslookup/mdns_sock.c')
| -rw-r--r-- | src/mslookup/mdns_sock.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/src/mslookup/mdns_sock.c b/src/mslookup/mdns_sock.c new file mode 100644 index 0000000..5291660 --- /dev/null +++ b/src/mslookup/mdns_sock.c @@ -0,0 +1,144 @@ +/* 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); +} |