428 lines
9.5 KiB
C
428 lines
9.5 KiB
C
/* BSC Multiplexer/NAT */
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/*
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* (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
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* (C) 2010 by on-waves.com
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* (C) 2009 by Harald Welte <laforge@gnumonks.org>
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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, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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#define _GNU_SOURCE
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#include <getopt.h>
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#include <openbsc/debug.h>
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#include <openbsc/msgb.h>
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#include <openbsc/bsc_msc.h>
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#include <openbsc/bsc_nat.h>
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#include <openbsc/ipaccess.h>
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#include <openbsc/abis_nm.h>
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#include <openbsc/talloc.h>
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#include <openbsc/linuxlist.h>
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#include <sccp/sccp.h>
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static const char *config_file = "openbsc.cfg";
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static char *msc_address = "127.0.0.1";
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static struct in_addr local_addr;
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static struct bsc_fd msc_connection;
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static struct bsc_fd bsc_connection;
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/*
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* Per BSC data structure
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*/
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struct bsc_connection {
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struct llist_head list_entry;
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/* do we know anything about this BSC? */
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int authenticated;
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/* the fd we use to communicate */
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struct bsc_fd bsc_fd;
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};
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static LLIST_HEAD(bsc_connections);
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/*
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* below are stubs we need to link
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*/
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int nm_state_event(enum nm_evt evt, u_int8_t obj_class, void *obj,
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struct gsm_nm_state *old_state, struct gsm_nm_state *new_state)
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{
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return -1;
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}
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void input_event(int event, enum e1inp_sign_type type, struct gsm_bts_trx *trx)
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{}
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int gsm0408_rcvmsg(struct msgb *msg, u_int8_t link_id)
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{
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return -1;
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}
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/*
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* Below is the handling of messages coming
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* from the MSC and need to be forwarded to
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* a real BSC.
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*/
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static void initialize_msc_if_needed()
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{
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static int init = 0;
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init = 1;
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/* do we need to send a GSM 08.08 message here? */
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}
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static void forward_sccp_to_bts(struct msgb *msg)
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{
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struct bsc_connection *bsc;
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struct bsc_nat_parsed *parsed;
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int rc;
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/* filter, drop, patch the message? */
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parsed = bsc_nat_parse(msg);
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if (!parsed) {
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LOGP(DNAT, LOGL_ERROR, "Can not parse msg from BSC.\n");
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return;
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}
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if (bsc_nat_filter_ipa(DIR_BSC, msg, parsed))
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goto exit;
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/* currently send this to every BSC connected */
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llist_for_each_entry(bsc, &bsc_connections, list_entry) {
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rc = write(bsc->bsc_fd.fd, msg->data, msg->len);
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/* try the next one */
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if (rc < msg->len)
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LOGP(DNAT, LOGL_ERROR, "Failed to write message to BTS: %d\n", rc);
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}
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exit:
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talloc_free(parsed);
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}
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static int ipaccess_msc_cb(struct bsc_fd *bfd, unsigned int what)
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{
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int error;
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struct msgb *msg = ipaccess_read_msg(bfd, &error);
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struct ipaccess_head *hh;
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if (!msg) {
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if (error == 0) {
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LOGP(DNAT, LOGL_FATAL, "The connection the MSC was lost, exiting\n");
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exit(-2);
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}
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LOGP(DNAT, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);
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return -1;
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}
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LOGP(DNAT, LOGL_DEBUG, "MSG from MSC: %s proto: %d\n", hexdump(msg->data, msg->len), msg->l2h[0]);
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/* handle base message handling */
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hh = (struct ipaccess_head *) msg->data;
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ipaccess_rcvmsg_base(msg, bfd);
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/* initialize the networking. This includes sending a GSM08.08 message */
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if (hh->proto == IPAC_PROTO_IPACCESS && msg->l2h[0] == IPAC_MSGT_ID_ACK)
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initialize_msc_if_needed();
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else if (hh->proto == IPAC_PROTO_SCCP)
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forward_sccp_to_bts(msg);
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return 0;
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}
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/*
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* Below is the handling of messages coming
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* from the BSC and need to be forwarded to
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* a real BSC.
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*/
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/*
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* Remove the connection from the connections list,
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* remove it from the patching of SCCP header lists
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* as well. Maybe in the future even close connection..
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*/
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static void remove_bsc_connection(struct bsc_connection *connection)
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{
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bsc_unregister_fd(&connection->bsc_fd);
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llist_del(&connection->list_entry);
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talloc_free(connection);
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}
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static int forward_sccp_to_msc(struct msgb *msg)
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{
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struct bsc_nat_parsed *parsed;
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int rc = -1;
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/* Parse and filter messages */
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parsed = bsc_nat_parse(msg);
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if (!parsed) {
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LOGP(DNAT, LOGL_ERROR, "Can not parse msg from BSC.\n");
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return -1;
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}
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if (bsc_nat_filter_ipa(DIR_MSC, msg, parsed))
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goto exit;
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/* send the non-filtered but maybe modified msg */
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rc = write(msc_connection.fd, msg->data, msg->len);
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exit:
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talloc_free(parsed);
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return rc;
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}
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static int ipaccess_bsc_cb(struct bsc_fd *bfd, unsigned int what)
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{
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int error;
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struct msgb *msg = ipaccess_read_msg(bfd, &error);
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if (!msg) {
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if (error == 0) {
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LOGP(DNAT, LOGL_ERROR, "The connection to the BSC was lost. Cleaning it\n");
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remove_bsc_connection((struct bsc_connection *) bfd->data);
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} else {
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LOGP(DNAT, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);
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}
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return -1;
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}
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LOGP(DNAT, LOGL_DEBUG, "MSG from BSC: %s proto: %d\n", hexdump(msg->data, msg->len), msg->l2h[0]);
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/* Handle messages from the BSC */
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/* FIXME: Currently no PONG is sent to the BSC */
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/* FIXME: Currently no ID ACK is sent to the BSC */
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forward_sccp_to_msc(msg);
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return 0;
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}
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static int ipaccess_listen_bsc_cb(struct bsc_fd *bfd, unsigned int what)
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{
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struct bsc_connection *bsc;
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int ret;
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struct sockaddr_in sa;
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socklen_t sa_len = sizeof(sa);
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if (!(what & BSC_FD_READ))
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return 0;
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ret = accept(bfd->fd, (struct sockaddr *) &sa, &sa_len);
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if (ret < 0) {
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perror("accept");
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return ret;
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}
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/* todo... do something with the connection */
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/* todo... use GNUtls to see if we want to trust this as a BTS */
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/*
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*
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*/
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bsc = talloc_zero(tall_bsc_ctx, struct bsc_connection);
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if (!bsc) {
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LOGP(DNAT, LOGL_ERROR, "Failed to allocate BSC struct.\n");
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close(ret);
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return -1;
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}
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bsc->bsc_fd.data = bsc;
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bsc->bsc_fd.fd = ret;
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bsc->bsc_fd.cb = ipaccess_bsc_cb;
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bsc->bsc_fd.when = BSC_FD_READ;
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if (bsc_register_fd(&bsc->bsc_fd) < 0) {
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LOGP(DNAT, LOGL_ERROR, "Failed to register BSC fd.\n");
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close(ret);
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talloc_free(bsc);
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return -2;
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}
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LOGP(DNAT, LOGL_INFO, "Registered new BSC\n");
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llist_add(&bsc->list_entry, &bsc_connections);
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ipaccess_send_id_ack(ret);
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return 0;
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}
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static int listen_for_bsc(struct bsc_fd *bfd, struct in_addr *in_addr, int port)
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{
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struct sockaddr_in addr;
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int ret, on = 1;
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bfd->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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bfd->cb = ipaccess_listen_bsc_cb;
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bfd->when = BSC_FD_READ;
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memset(&addr, 0, sizeof(addr));
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addr.sin_family = AF_INET;
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addr.sin_port = htons(port);
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addr.sin_addr.s_addr = in_addr->s_addr;
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setsockopt(bfd->fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
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ret = bind(bfd->fd, (struct sockaddr *) &addr, sizeof(addr));
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if (ret < 0) {
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fprintf(stderr, "Could not bind the BSC socket %s\n",
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strerror(errno));
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return -EIO;
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}
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ret = listen(bfd->fd, 1);
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if (ret < 0) {
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perror("listen");
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return ret;
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}
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ret = bsc_register_fd(bfd);
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if (ret < 0) {
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perror("register_listen_fd");
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return ret;
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}
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return 0;
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}
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static void print_usage()
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{
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printf("Usage: bsc_nat\n");
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}
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static void print_help()
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{
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printf(" Some useful help...\n");
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printf(" -h --help this text\n");
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printf(" -d option --debug=DRLL:DCC:DMM:DRR:DRSL:DNM enable debugging\n");
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printf(" -s --disable-color\n");
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printf(" -c --config-file filename The config file to use.\n");
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printf(" -m --msc=IP. The address of the MSC.\n");
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printf(" -l --local=IP. The local address of this BSC.\n");
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}
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static void handle_options(int argc, char** argv)
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{
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while (1) {
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int option_index = 0, c;
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static struct option long_options[] = {
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{"help", 0, 0, 'h'},
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{"debug", 1, 0, 'd'},
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{"config-file", 1, 0, 'c'},
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{"disable-color", 0, 0, 's'},
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{"timestamp", 0, 0, 'T'},
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{"msc", 1, 0, 'm'},
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{"local", 1, 0, 'l'},
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{0, 0, 0, 0}
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};
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c = getopt_long(argc, argv, "hd:sTPc:m:l:",
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long_options, &option_index);
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if (c == -1)
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break;
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switch (c) {
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case 'h':
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print_usage();
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print_help();
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exit(0);
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case 's':
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debug_use_color(0);
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break;
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case 'd':
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debug_parse_category_mask(optarg);
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break;
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case 'c':
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config_file = strdup(optarg);
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break;
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case 'T':
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debug_timestamp(1);
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break;
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case 'm':
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msc_address = strdup(optarg);
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break;
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case 'l':
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inet_aton(optarg, &local_addr);
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break;
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default:
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/* ignore */
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break;
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}
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}
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}
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static void signal_handler(int signal)
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{
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switch (signal) {
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case SIGABRT:
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/* in case of abort, we want to obtain a talloc report
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* and then return to the caller, who will abort the process */
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case SIGUSR1:
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talloc_report_full(tall_bsc_ctx, stderr);
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break;
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default:
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break;
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}
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}
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int main(int argc, char** argv)
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{
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int rc;
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/* parse options */
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local_addr.s_addr = INADDR_ANY;
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handle_options(argc, argv);
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/* seed the PRNG */
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srand(time(NULL));
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/* connect to the MSC */
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msc_connection.cb = ipaccess_msc_cb;
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rc = connect_to_msc(&msc_connection, msc_address, 5000);
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if (rc < 0) {
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fprintf(stderr, "Opening the MSC connection failed.\n");
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exit(1);
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}
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/* wait for the BSC */
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if (listen_for_bsc(&bsc_connection, &local_addr, 5000) < 0) {
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fprintf(stderr, "Failed to listen for BSC.\n");
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exit(1);
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}
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signal(SIGINT, &signal_handler);
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signal(SIGABRT, &signal_handler);
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signal(SIGUSR1, &signal_handler);
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signal(SIGPIPE, SIG_IGN);
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while (1) {
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bsc_select_main(0);
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}
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return 0;
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}
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