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/* USSD Filter Code */
/*
* (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/bsc_nat_sccp.h>
#include <osmocore/protocol/gsm_08_08.h>
#include <osmocore/gsm0480.h>
#include <string.h>
int bsc_check_ussd(struct sccp_connections *con, struct bsc_nat_parsed *parsed,
struct msgb *msg)
{
uint32_t len;
uint8_t msg_type;
struct gsm48_hdr *hdr48;
struct bsc_nat_acc_lst *lst;
struct ussd_request req;
/*
* various checks to avoid the decoding work. Right now we only want to
* decode if the connection was created for USSD, we do have a USSD access
* list, a query, a IMSI and such...
*/
if (con->con_type != NAT_CON_TYPE_SSA)
return 0;
if (!con->imsi)
return 0;
if (!con->bsc->nat->ussd_lst_name)
return 0;
if (!con->bsc->nat->ussd_query)
return 0;
if (parsed->bssap != BSSAP_MSG_DTAP)
return 0;
if (strlen(con->imsi) > GSM_IMSI_LENGTH)
return 0;
hdr48 = bsc_unpack_dtap(parsed, msg, &len);
if (!hdr48)
return 0;
msg_type = hdr48->msg_type & 0xbf;
if (hdr48->proto_discr != GSM48_PDISC_NC_SS || msg_type != GSM0480_MTYPE_REGISTER)
return 0;
/* now check if it is a IMSI we care about */
lst = bsc_nat_acc_lst_find(con->bsc->nat, con->bsc->nat->ussd_lst_name);
if (!lst)
return 0;
if (bsc_nat_lst_check_allow(lst, con->imsi) != 0)
return 0;
/* now decode the message and see if we really want to handle it */
memset(&req, 0, sizeof(req));
if (gsm0480_decode_ussd_request(hdr48, len, &req) != 1)
return 0;
if (req.text[0] == 0xff)
return 0;
if (strcmp(req.text, con->bsc->nat->ussd_query) != 0)
return 0;
/* found a USSD query for our subscriber */
LOGP(DNAT, LOGL_NOTICE, "Found USSD query for %s\n", con->imsi);
return 1;
}
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