aboutsummaryrefslogtreecommitdiffstats
path: root/openbsc/src/osmo-bsc_nat/bsc_ussd.c
blob: 108241421faa7397a4ac13af66a0d8ef2f797fdd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
/* USSD Filter Code */

/*
 * (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
 * (C) 2010-2011 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 Affero General Public License as published by
 * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <openbsc/bsc_nat.h>
#include <openbsc/bsc_nat_sccp.h>
#include <openbsc/bsc_msg_filter.h>
#include <openbsc/ipaccess.h>
#include <openbsc/socket.h>

#include <osmocom/gsm/protocol/gsm_08_08.h>
#include <osmocom/gsm/gsm0480.h>
#include <osmocom/core/talloc.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/gsm/ipa.h>

#include <osmocom/sccp/sccp.h>

#include <osmocom/abis/ipa.h>

#include <sys/socket.h>
#include <string.h>
#include <unistd.h>

#define USSD_LAC_IE	0
#define USSD_CI_IE	1

static void ussd_auth_con(struct tlv_parsed *, struct bsc_nat_ussd_con *);

static struct bsc_nat_ussd_con *bsc_nat_ussd_alloc(struct bsc_nat *nat)
{
	struct bsc_nat_ussd_con *con;

	con = talloc_zero(nat, struct bsc_nat_ussd_con);
	if (!con)
		return NULL;

	con->nat = nat;
	return con;
}

static void bsc_nat_ussd_destroy(struct bsc_nat_ussd_con *con)
{
	if (con->nat->ussd_con == con) {
		bsc_ussd_close_connections(con->nat);
		con->nat->ussd_con = NULL;
	}

	close(con->queue.bfd.fd);
	osmo_fd_unregister(&con->queue.bfd);
	osmo_timer_del(&con->auth_timeout);
	osmo_wqueue_clear(&con->queue);

	msgb_free(con->pending_msg);
	talloc_free(con);
}

static void ussd_pong(struct bsc_nat_ussd_con *conn)
{
	struct msgb *msg;

	msg = msgb_alloc_headroom(4096, 128, "pong message");
	if (!msg) {
		LOGP(DNAT, LOGL_ERROR, "Failed to allocate pong msg\n");
		return;
	}

	msgb_v_put(msg, IPAC_MSGT_PONG);
	bsc_do_write(&conn->queue, msg, IPAC_PROTO_IPACCESS);
}

static int forward_sccp(struct bsc_nat *nat, struct msgb *msg)
{
	struct nat_sccp_connection *con;
	struct bsc_nat_parsed *parsed;


	parsed = bsc_nat_parse(msg);
	if (!parsed) {
		LOGP(DNAT, LOGL_ERROR, "Can not parse msg from USSD.\n");
		msgb_free(msg);
		return -1;
	}

	if (!parsed->dest_local_ref) {
		LOGP(DNAT, LOGL_ERROR, "No destination local reference.\n");
		msgb_free(msg);
		return -1;
	}

	con = bsc_nat_find_con_by_bsc(nat, parsed->dest_local_ref);
	if (!con || !con->bsc) {
		LOGP(DNAT, LOGL_ERROR, "No active connection found.\n");
		msgb_free(msg);
		return -1;
	}

	talloc_free(parsed);
	bsc_write_msg(&con->bsc->write_queue, msg);
	return 0;
}

static int ussd_read_cb(struct osmo_fd *bfd)
{
	struct bsc_nat_ussd_con *conn = bfd->data;
	struct msgb *msg = NULL;
	struct ipaccess_head *hh;
	int ret;

	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &conn->pending_msg);
	if (ret <= 0) {
		if (ret == -EAGAIN)
			return 0;
		LOGP(DNAT, LOGL_ERROR, "USSD Connection was lost.\n");
		bsc_nat_ussd_destroy(conn);
		return -1;
	}

	LOGP(DNAT, LOGL_NOTICE, "MSG from USSD: %s proto: %d\n",
		osmo_hexdump(msg->data, msg->len), msg->l2h[0]);
	hh = (struct ipaccess_head *) msg->data;

	if (hh->proto == IPAC_PROTO_IPACCESS) {
		if (msg->l2h[0] == IPAC_MSGT_ID_RESP) {
			struct tlv_parsed tvp;
			int ret;
			ret = ipa_ccm_idtag_parse(&tvp,
					     (unsigned char *) msg->l2h + 2,
					     msgb_l2len(msg) - 2);
			if (ret < 0) {
				LOGP(DNAT, LOGL_ERROR, "ignoring IPA response "
					"message with malformed TLVs\n");
				msgb_free(msg);
				return ret;
			}
			if (TLVP_PRESENT(&tvp, IPAC_IDTAG_UNITNAME))
				ussd_auth_con(&tvp, conn);
		} else if (msg->l2h[0] == IPAC_MSGT_PING) {
			LOGP(DNAT, LOGL_DEBUG, "Got USSD ping request.\n");
			ussd_pong(conn);
		} else {
			LOGP(DNAT, LOGL_NOTICE, "Got unknown IPACCESS message 0x%02x.\n", msg->l2h[0]);
		}

		msgb_free(msg);
	} else if (hh->proto == IPAC_PROTO_SCCP) {
		forward_sccp(conn->nat, msg);
	} else {
		msgb_free(msg);
	}

	return 0;
}

static void ussd_auth_cb(void *_data)
{
	LOGP(DNAT, LOGL_ERROR, "USSD module didn't authenticate\n");
	bsc_nat_ussd_destroy((struct bsc_nat_ussd_con *) _data);
}

static void ussd_auth_con(struct tlv_parsed *tvp, struct bsc_nat_ussd_con *conn)
{
	const char *token;
	int len;
	if (!conn->nat->ussd_token) {
		LOGP(DNAT, LOGL_ERROR, "No USSD token set. Closing\n");
		bsc_nat_ussd_destroy(conn);
		return;
	}

	token = (const char *) TLVP_VAL(tvp, IPAC_IDTAG_UNITNAME);
 	len = TLVP_LEN(tvp, IPAC_IDTAG_UNITNAME);

	/* last byte should be a NULL */
	if (strlen(conn->nat->ussd_token) != len - 1)
		goto disconnect;
	/* compare everything including the null byte */
	if (memcmp(conn->nat->ussd_token, token, len) != 0)
		goto disconnect;

	/* it is authenticated now */
	if (conn->nat->ussd_con && conn->nat->ussd_con != conn)
		bsc_nat_ussd_destroy(conn->nat->ussd_con);

	LOGP(DNAT, LOGL_ERROR, "USSD token specified. USSD provider is connected.\n");
	osmo_timer_del(&conn->auth_timeout);
	conn->authorized = 1;
	conn->nat->ussd_con = conn;
	return;

disconnect:
	LOGP(DNAT, LOGL_ERROR, "Wrong USSD token by client: %d\n",
		conn->queue.bfd.fd);
	bsc_nat_ussd_destroy(conn);
}

static void ussd_start_auth(struct bsc_nat_ussd_con *conn)
{
	struct msgb *msg;

	conn->auth_timeout.data = conn;
	conn->auth_timeout.cb = ussd_auth_cb;
	osmo_timer_schedule(&conn->auth_timeout, conn->nat->auth_timeout, 0);

	msg = msgb_alloc_headroom(4096, 128, "auth message");
	if (!msg) {
		LOGP(DNAT, LOGL_ERROR, "Failed to allocate auth msg\n");
		return;
	}

	msgb_v_put(msg, IPAC_MSGT_ID_GET);
	bsc_do_write(&conn->queue, msg, IPAC_PROTO_IPACCESS);
}

static int ussd_listen_cb(struct osmo_fd *bfd, unsigned int what)
{
	struct bsc_nat_ussd_con *conn;
	struct bsc_nat *nat;
	struct sockaddr_in sa;
	socklen_t sa_len = sizeof(sa);
	int fd;

	if (!(what & BSC_FD_READ))
		return 0;

	fd = accept(bfd->fd, (struct sockaddr *) &sa, &sa_len);
	if (fd < 0) {
		perror("accept");
		return fd;
	}

	nat = (struct bsc_nat *) bfd->data;
	osmo_counter_inc(nat->stats.ussd.reconn);

	conn = bsc_nat_ussd_alloc(nat);
	if (!conn) {
		LOGP(DNAT, LOGL_ERROR, "Failed to allocate USSD con struct.\n");
		close(fd);
		return -1;
	}

	osmo_wqueue_init(&conn->queue, 10);
	conn->queue.bfd.data = conn;
	conn->queue.bfd.fd = fd;
	conn->queue.bfd.when = BSC_FD_READ;
	conn->queue.read_cb = ussd_read_cb;
	conn->queue.write_cb = bsc_write_cb;

	if (osmo_fd_register(&conn->queue.bfd) < 0) {
		LOGP(DNAT, LOGL_ERROR, "Failed to register USSD fd.\n");
		bsc_nat_ussd_destroy(conn);
		return -1;
	}

	LOGP(DNAT, LOGL_NOTICE, "USSD Connection on %d with IP: %s\n",
	     fd, inet_ntoa(sa.sin_addr));

	/* do authentication */
	ussd_start_auth(conn);
	return 0;
}

int bsc_ussd_init(struct bsc_nat *nat)
{
	struct in_addr addr;

	addr.s_addr = INADDR_ANY;
	if (nat->ussd_local)
		inet_aton(nat->ussd_local, &addr);

	nat->ussd_listen.data = nat;
	return make_sock(&nat->ussd_listen, IPPROTO_TCP,
			 ntohl(addr.s_addr), 5001, 0, ussd_listen_cb, nat);
}

static int forward_ussd_simple(struct nat_sccp_connection *con, struct msgb *input)
{
	struct msgb *copy;
	struct bsc_nat_ussd_con *ussd;

	if (!con->bsc->nat->ussd_con)
		return -1;

	copy = msgb_alloc_headroom(4096, 128, "forward bts");
	if (!copy) {
		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
		return -1;
	}

	/* copy the data into the copy */
	copy->l2h = msgb_put(copy, msgb_l2len(input));
	memcpy(copy->l2h, input->l2h, msgb_l2len(input));

	/* send it out */
	ussd = con->bsc->nat->ussd_con;
	bsc_do_write(&ussd->queue, copy, IPAC_PROTO_SCCP);
	return 0;
}

static int forward_ussd(struct nat_sccp_connection *con, const struct ussd_request *req,
			struct msgb *input)
{
	struct msgb *msg, *copy;
	struct ipac_msgt_sccp_state *state;
	struct bsc_nat_ussd_con *ussd;
	uint16_t lac, ci;

	if (!con->bsc->nat->ussd_con)
		return -1;

	msg = msgb_alloc_headroom(4096, 128, "forward ussd");
	if (!msg) {
		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
		return -1;
	}

	copy = msgb_alloc_headroom(4096, 128, "forward bts");
	if (!copy) {
		LOGP(DNAT, LOGL_ERROR, "Allocation failed, not forwarding.\n");
		msgb_free(msg);
		return -1;
	}

	copy->l2h = msgb_put(copy, msgb_l2len(input));
	memcpy(copy->l2h, input->l2h, msgb_l2len(input));

	msg->l2h = msgb_put(msg, 1);
	msg->l2h[0] = IPAC_MSGT_SCCP_OLD;

	/* fill out the data */
	state = (struct ipac_msgt_sccp_state *) msgb_put(msg, sizeof(*state));
	state->trans_id = req->transaction_id;
	state->invoke_id = req->invoke_id;
	memcpy(&state->src_ref, &con->remote_ref, sizeof(con->remote_ref));
	memcpy(&state->dst_ref, &con->real_ref, sizeof(con->real_ref));
	memcpy(state->imsi, con->filter_state.imsi, strlen(con->filter_state.imsi));

	/* add additional tag/values */
	lac = htons(con->lac);
	ci = htons(con->ci);
	msgb_tv_fixed_put(msg, USSD_LAC_IE, sizeof(lac), (const uint8_t *) &lac);
	msgb_tv_fixed_put(msg, USSD_CI_IE, sizeof(ci), (const uint8_t *) &ci);

	ussd = con->bsc->nat->ussd_con;
	bsc_do_write(&ussd->queue, msg, IPAC_PROTO_IPACCESS);
	bsc_do_write(&ussd->queue, copy, IPAC_PROTO_SCCP);

	return 0;
}

int bsc_ussd_check(struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
		   struct msgb *msg)
{
	uint32_t len;
	uint8_t msg_type;
	uint8_t proto;
	uint8_t ti;
	struct gsm48_hdr *hdr48;
	struct bsc_msg_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->filter_state.con_type != FLT_CON_TYPE_SSA)
		return 0;

	if (!con->filter_state.imsi)
		return 0;

	/* We have not verified the IMSI yet */
	if (!con->authorized)
		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->filter_state.imsi) >= GSM_IMSI_LENGTH)
		return 0;

	hdr48 = bsc_unpack_dtap(parsed, msg, &len);
	if (!hdr48)
		return 0;

	proto = hdr48->proto_discr & 0x0f;
	msg_type = hdr48->msg_type & 0xbf;
	ti = (hdr48->proto_discr & 0x70) >> 4;
	if (proto != GSM48_PDISC_NC_SS)
		return 0;

	if (msg_type == GSM0480_MTYPE_REGISTER) {

		/* now check if it is a IMSI we care about */
		lst = bsc_msg_acc_lst_find(&con->bsc->nat->access_lists,
					   con->bsc->nat->ussd_lst_name);
		if (!lst)
			return 0;

		if (bsc_msg_acc_lst_check_allow(lst, con->filter_state.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 (regexec(&con->bsc->nat->ussd_query_re,
			    req.text, 0, NULL, 0) == REG_NOMATCH)
			return 0;

		/* found a USSD query for our subscriber */
		LOGP(DNAT, LOGL_NOTICE, "Found USSD query for %s\n",
			con->filter_state.imsi);
		con->ussd_ti[ti] = 1;
		if (forward_ussd(con, &req, msg) != 0)
			return 0;
		return 1;
	} else if (msg_type == GSM0480_MTYPE_FACILITY && con->ussd_ti[ti]) {
		LOGP(DNAT, LOGL_NOTICE, "Forwarding message part of TI: %d %s\n",
		     ti, con->filter_state.imsi);
		if (forward_ussd_simple(con, msg) != 0)
			return 0;
		return 1;
	}

	return 0;
}