openbsc/src/nat/bsc_mgcp_utils.c

/*
 * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
 * (C) 2010 by On-Waves
 * 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <openbsc/bsc_nat.h>
#include <openbsc/gsm_data.h>
#include <openbsc/bssap.h>
#include <openbsc/debug.h>

#include <netinet/in.h>
#include <arpa/inet.h>

int bsc_mgcp_assign(struct sccp_connections *con, struct msgb *msg)
{
	struct tlv_parsed tp;
	u_int16_t cic;
	u_int8_t timeslot;
	u_int8_t multiplex;

	if (!msg->l3h) {
		LOGP(DNAT, LOGL_ERROR, "Assignment message should have l3h pointer.\n");
		return -1;
	}

	if (msgb_l3len(msg) < 3) {
		LOGP(DNAT, LOGL_ERROR, "Assignment message has not enough space for GSM0808.\n");
		return -1;
	}

	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
	if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
		LOGP(DNAT, LOGL_ERROR, "Circuit identity code not found in assignment message.\n");
		return -1;
	}

	cic = ntohs(*(u_int16_t *)TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
	timeslot = cic & 0x1f;
	multiplex = (cic & ~0x1f) >> 5;

	con->msc_timeslot = (32 * multiplex) + timeslot;
	con->bsc_timeslot = con->msc_timeslot;
	return 0;
}

void bsc_mgcp_clear(struct sccp_connections *con)
{
	con->msc_timeslot = -1;
	con->bsc_timeslot = -1;
}