aboutsummaryrefslogtreecommitdiffstats
path: root/openbsc/src/gprs/sgsn_libgtp.c
blob: 3d3173a11556a33104143efd95db86e46d3b34d9 (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
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
/* GPRS SGSN integration with libgtp of OpenGGSN */
/* libgtp implements the GPRS Tunelling Protocol GTP per TS 09.60 / 29.060 */

/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
 * (C) 2010 by On-Waves
 * (C) 2015 by Holger Hans Peter Freyther
 * 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 <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <errno.h>
#include <signal.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <osmocom/core/talloc.h>
#include <osmocom/core/select.h>
#include <osmocom/core/rate_ctr.h>
#include <osmocom/crypt/auth.h>
#include <osmocom/gprs/gprs_bssgp.h>

#include <openbsc/gsm_04_08_gprs.h>
#include <openbsc/signal.h>
#include <openbsc/debug.h>
#include <openbsc/sgsn.h>
#include <openbsc/gprs_llc.h>
#include <openbsc/gprs_sgsn.h>
#include <openbsc/gprs_gmm.h>
#include <openbsc/gsm_subscriber.h>
#include <openbsc/iu.h>

#include <osmocom/ranap/ranap_ies_defs.h>

#include <gtp.h>
#include <pdp.h>

const struct value_string gtp_cause_strs[] = {
	{ GTPCAUSE_REQ_IMSI, "Request IMSI" },
	{ GTPCAUSE_REQ_IMEI, "Request IMEI" },
	{ GTPCAUSE_REQ_IMSI_IMEI, "Request IMSI and IMEI" },
	{ GTPCAUSE_NO_ID_NEEDED, "No identity needed" },
	{ GTPCAUSE_MS_REFUSES_X, "MS refuses" },
	{ GTPCAUSE_MS_NOT_RESP_X, "MS is not GPRS responding" },
	{ GTPCAUSE_ACC_REQ, "Request accepted" },
	{ GTPCAUSE_NON_EXIST, "Non-existent" },
	{ GTPCAUSE_INVALID_MESSAGE, "Invalid message format" },
	{ GTPCAUSE_IMSI_NOT_KNOWN, "IMSI not known" },
	{ GTPCAUSE_MS_DETACHED, "MS is GPRS detached" },
	{ GTPCAUSE_MS_NOT_RESP, "MS is not GPRS responding" },
	{ GTPCAUSE_MS_REFUSES, "MS refuses" },
	{ GTPCAUSE_NO_RESOURCES, "No resources available" },
	{ GTPCAUSE_NOT_SUPPORTED, "Service not supported" },
	{ GTPCAUSE_MAN_IE_INCORRECT, "Mandatory IE incorrect" },
	{ GTPCAUSE_MAN_IE_MISSING, "Mandatory IE missing" },
	{ GTPCAUSE_OPT_IE_INCORRECT, "Optional IE incorrect" },
	{ GTPCAUSE_SYS_FAIL, "System failure" },
	{ GTPCAUSE_ROAMING_REST, "Roaming restrictions" },
	{ GTPCAUSE_PTIMSI_MISMATCH, "P-TMSI Signature mismatch" },
	{ GTPCAUSE_CONN_SUSP, "GPRS connection suspended" },
	{ GTPCAUSE_AUTH_FAIL, "Authentication failure" },
	{ GTPCAUSE_USER_AUTH_FAIL, "User authentication failed" },
	{ GTPCAUSE_CONTEXT_NOT_FOUND, "Context not found" },
	{ GTPCAUSE_ADDR_OCCUPIED, "All dynamic PDP addresses occupied" },
	{ GTPCAUSE_NO_MEMORY, "No memory is available" },
	{ GTPCAUSE_RELOC_FAIL, "Relocation failure" },
	{ GTPCAUSE_UNKNOWN_MAN_EXTHEADER, "Unknown mandatory ext. header" },
	{ GTPCAUSE_SEM_ERR_TFT, "Semantic error in TFT operation" },
	{ GTPCAUSE_SYN_ERR_TFT, "Syntactic error in TFT operation" },
	{ GTPCAUSE_SEM_ERR_FILTER, "Semantic errors in packet filter" },
	{ GTPCAUSE_SYN_ERR_FILTER, "Syntactic errors in packet filter" },
	{ GTPCAUSE_MISSING_APN, "Missing or unknown APN" },
	{ GTPCAUSE_UNKNOWN_PDP, "Unknown PDP address or PDP type" },
	{ 0, NULL }
};

/* Generate the GTP IMSI IE according to 09.60 Section 7.9.2 */
static uint64_t imsi_str2gtp(char *str)
{
	uint64_t imsi64 = 0;
	unsigned int n;
	unsigned int imsi_len = strlen(str);

	if (imsi_len > 16) {
		LOGP(DGPRS, LOGL_NOTICE, "IMSI length > 16 not supported!\n");
		return 0;
	}

	for (n = 0; n < 16; n++) {
		uint64_t val;
		if (n < imsi_len)
			val = (str[n]-'0') & 0xf;
		else
			val = 0xf;
		imsi64 |= (val << (n*4));
	}
	return imsi64;
}

/* generate a PDP context based on the IE's from the 04.08 message,
 * and send the GTP create pdp context request to the GGSN */
struct sgsn_pdp_ctx *sgsn_create_pdp_ctx(struct sgsn_ggsn_ctx *ggsn,
					 struct sgsn_mm_ctx *mmctx,
					 uint16_t nsapi,
					 struct tlv_parsed *tp)
{
	struct gprs_ra_id raid;
	struct sgsn_pdp_ctx *pctx;
	struct pdp_t *pdp;
	uint64_t imsi_ui64;
	size_t qos_len;
	const uint8_t *qos;
	int rc;

	LOGP(DGPRS, LOGL_ERROR, "Create PDP Context\n");
	pctx = sgsn_pdp_ctx_alloc(mmctx, nsapi);
	if (!pctx) {
		LOGP(DGPRS, LOGL_ERROR, "Couldn't allocate PDP Ctx\n");
		return NULL;
	}

	imsi_ui64 = imsi_str2gtp(mmctx->imsi);

	rc = pdp_newpdp(&pdp, imsi_ui64, nsapi, NULL);
	if (rc) {
		LOGP(DGPRS, LOGL_ERROR, "Out of libgtp PDP Contexts\n");
		return NULL;
	}
	pdp->priv = pctx;
	pctx->lib = pdp;
	pctx->ggsn = ggsn;

	//pdp->peer =	/* sockaddr_in of GGSN (receive) */
	//pdp->ipif =	/* not used by library */
	pdp->version = ggsn->gtp_version;
	pdp->hisaddr0 =	ggsn->remote_addr;
	pdp->hisaddr1 = ggsn->remote_addr;
	//pdp->cch_pdp = 512;	/* Charging Flat Rate */

	/* MS provided APN, subscription was verified by the caller */
	pdp->selmode = 0xFC | 0x00;

	/* IMSI, TEID/TEIC, FLLU/FLLC, TID, NSAPI set in pdp_newpdp */

	/* Put the MSISDN in case we have it */
	if (mmctx->subscr) {
		pdp->msisdn.l = mmctx->subscr->sgsn_data->msisdn_len;
		if (pdp->msisdn.l > sizeof(pdp->msisdn.v))
			pdp->msisdn.l = sizeof(pdp->msisdn.v);
		memcpy(pdp->msisdn.v, mmctx->subscr->sgsn_data->msisdn,
			pdp->msisdn.l);
	}

	/* End User Address from GMM requested PDP address */
	pdp->eua.l = TLVP_LEN(tp, OSMO_IE_GSM_REQ_PDP_ADDR);
	if (pdp->eua.l > sizeof(pdp->eua.v))
		pdp->eua.l = sizeof(pdp->eua.v);
	memcpy(pdp->eua.v, TLVP_VAL(tp, OSMO_IE_GSM_REQ_PDP_ADDR),
		pdp->eua.l);
	/* Highest 4 bits of first byte need to be set to 1, otherwise
	 * the IE is identical with the 04.08 PDP Address IE */
	pdp->eua.v[0] |= 0xf0;

	/* APN name from GMM */
	pdp->apn_use.l = TLVP_LEN(tp, GSM48_IE_GSM_APN);
	if (pdp->apn_use.l > sizeof(pdp->apn_use.v))
		pdp->apn_use.l = sizeof(pdp->apn_use.v);
	memcpy(pdp->apn_use.v, TLVP_VAL(tp, GSM48_IE_GSM_APN),
		pdp->apn_use.l);

	/* Protocol Configuration Options from GMM */
	pdp->pco_req.l = TLVP_LEN(tp, GSM48_IE_GSM_PROTO_CONF_OPT);
	if (pdp->pco_req.l > sizeof(pdp->pco_req.v))
		pdp->pco_req.l = sizeof(pdp->pco_req.v);
	memcpy(pdp->pco_req.v, TLVP_VAL(tp, GSM48_IE_GSM_PROTO_CONF_OPT),
		pdp->pco_req.l);

	/* QoS options from GMM or remote */
	if (TLVP_LEN(tp, OSMO_IE_GSM_SUB_QOS) > 0) {
		qos_len = TLVP_LEN(tp, OSMO_IE_GSM_SUB_QOS);
		qos = TLVP_VAL(tp, OSMO_IE_GSM_SUB_QOS);
	} else {
		qos_len = TLVP_LEN(tp, OSMO_IE_GSM_REQ_QOS);
		qos = TLVP_VAL(tp, OSMO_IE_GSM_REQ_QOS);
	}

	if (qos_len <= 3) {
		pdp->qos_req.l = qos_len + 1;
		if (pdp->qos_req.l > sizeof(pdp->qos_req.v))
			pdp->qos_req.l = sizeof(pdp->qos_req.v);
		pdp->qos_req.v[0] = 0; /* Allocation/Retention policy */
		memcpy(&pdp->qos_req.v[1], qos, pdp->qos_req.l - 1);
	} else {
		pdp->qos_req.l = qos_len;
		if (pdp->qos_req.l > sizeof(pdp->qos_req.v))
			pdp->qos_req.l = sizeof(pdp->qos_req.v);
		memcpy(pdp->qos_req.v, qos, pdp->qos_req.l);
	}

	/* SGSN address for control plane */
	pdp->gsnlc.l = sizeof(sgsn->cfg.gtp_listenaddr.sin_addr);
	memcpy(pdp->gsnlc.v, &sgsn->cfg.gtp_listenaddr.sin_addr,
		sizeof(sgsn->cfg.gtp_listenaddr.sin_addr));

	/* SGSN address for user plane
	 * Default to the control plane addr for now. If we are connected to a
	 * hnbgw via IuPS we'll need to send a PDP context update with the
	 * correct IP address after the RAB Assignment is complete */
	pdp->gsnlu.l = sizeof(sgsn->cfg.gtp_listenaddr.sin_addr);
	memcpy(pdp->gsnlu.v, &sgsn->cfg.gtp_listenaddr.sin_addr,
		sizeof(sgsn->cfg.gtp_listenaddr.sin_addr));

	/* Assume we are a GERAN system */
	pdp->rattype.l = 1;
	pdp->rattype.v[0] = 2;
	pdp->rattype_given = 1;

	/* Include RAI and ULI all the time */
	pdp->rai_given = 1;
	pdp->rai.l = 6;
	raid = mmctx->ra;
	raid.lac = 0xFFFE;
	raid.rac = 0xFF;
	gsm48_construct_ra(pdp->rai.v, &raid);

	pdp->userloc_given = 1;
	pdp->userloc.l = 8;
	pdp->userloc.v[0] = 0; /* CGI for GERAN */
	bssgp_create_cell_id(&pdp->userloc.v[1], &mmctx->ra, mmctx->gb.cell_id);

	/* include the IMEI(SV) */
	pdp->imeisv_given = 1;
	gsm48_encode_bcd_number(&pdp->imeisv.v[0], 8, 0, mmctx->imei);
	pdp->imeisv.l = pdp->imeisv.v[0];
	memmove(&pdp->imeisv.v[0], &pdp->imeisv.v[1], 8);

	/* change pdp state to 'requested' */
	pctx->state = PDP_STATE_CR_REQ;

	rc = gtp_create_context_req(ggsn->gsn, pdp, pctx);
	/* FIXME */

	return pctx;
}

/* SGSN wants to delete a PDP context */
int sgsn_delete_pdp_ctx(struct sgsn_pdp_ctx *pctx)
{
	LOGPDPCTXP(LOGL_ERROR, pctx, "Delete PDP Context\n");

	/* FIXME: decide if we need teardown or not ! */
	return gtp_delete_context_req(pctx->ggsn->gsn, pctx->lib, pctx, 1);
}

struct cause_map {
	uint8_t cause_in;
	uint8_t cause_out;
};

static uint8_t cause_map(const struct cause_map *map, uint8_t in, uint8_t deflt)
{
	const struct cause_map *m;

	for (m = map; m->cause_in && m->cause_out; m++) {
		if (m->cause_in == in)
			return m->cause_out;
	}
	return deflt;
}

/* how do we map from gtp cause to SM cause */
static const struct cause_map gtp2sm_cause_map[] = {
	{ GTPCAUSE_NO_RESOURCES, 	GSM_CAUSE_INSUFF_RSRC },
	{ GTPCAUSE_NOT_SUPPORTED,	GSM_CAUSE_SERV_OPT_NOTSUPP },
	{ GTPCAUSE_MAN_IE_INCORRECT,	GSM_CAUSE_INV_MAND_INFO },
	{ GTPCAUSE_MAN_IE_MISSING,	GSM_CAUSE_INV_MAND_INFO },
	{ GTPCAUSE_OPT_IE_INCORRECT,	GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_SYS_FAIL,		GSM_CAUSE_NET_FAIL },
	{ GTPCAUSE_ROAMING_REST,	GSM_CAUSE_REQ_SERV_OPT_NOTSUB },
	{ GTPCAUSE_PTIMSI_MISMATCH,	GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_CONN_SUSP,		GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_AUTH_FAIL,		GSM_CAUSE_AUTH_FAILED },
	{ GTPCAUSE_USER_AUTH_FAIL,	GSM_CAUSE_ACT_REJ_GGSN },
	{ GTPCAUSE_CONTEXT_NOT_FOUND,	GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_ADDR_OCCUPIED,	GSM_CAUSE_INSUFF_RSRC },
	{ GTPCAUSE_NO_MEMORY,		GSM_CAUSE_INSUFF_RSRC },
	{ GTPCAUSE_RELOC_FAIL,		GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_UNKNOWN_MAN_EXTHEADER, GSM_CAUSE_PROTO_ERR_UNSPEC },
	{ GTPCAUSE_MISSING_APN,		GSM_CAUSE_MISSING_APN },
	{ GTPCAUSE_UNKNOWN_PDP,		GSM_CAUSE_UNKNOWN_PDP },
	{ 0, 0 }
};

static int send_act_pdp_cont_acc(struct sgsn_pdp_ctx *pctx)
{
	struct sgsn_signal_data sig_data;

	/* Inform others about it */
	memset(&sig_data, 0, sizeof(sig_data));
	sig_data.pdp = pctx;
	osmo_signal_dispatch(SS_SGSN, S_SGSN_PDP_ACT, &sig_data);

	/* Send PDP CTX ACT to MS */
	return gsm48_tx_gsm_act_pdp_acc(pctx);
}

/* The GGSN has confirmed the creation of a PDP Context */
static int create_pdp_conf(struct pdp_t *pdp, void *cbp, int cause)
{
	struct sgsn_signal_data sig_data;
	struct sgsn_pdp_ctx *pctx = cbp;
	uint8_t reject_cause;

	LOGPDPCTXP(LOGL_INFO, pctx, "Received CREATE PDP CTX CONF, cause=%d(%s)\n",
		cause, get_value_string(gtp_cause_strs, cause));

	if (!pctx->mm) {
		LOGP(DGPRS, LOGL_INFO,
		     "No MM context, aborting CREATE PDP CTX CONF\n");
		return -EIO;
	}

	/* Check for cause value if it was really successful */
	if (cause < 0) {
		LOGP(DGPRS, LOGL_NOTICE, "Create PDP ctx req timed out\n");
		if (pdp && pdp->version == 1) {
			pdp->version = 0;
			gtp_create_context_req(sgsn->gsn, pdp, cbp);
			return 0;
		} else {
			reject_cause = GSM_CAUSE_NET_FAIL;
			goto reject;
		}
	}

	/* Check for cause value if it was really successful */
	if (cause != GTPCAUSE_ACC_REQ) {
		reject_cause = cause_map(gtp2sm_cause_map, cause,
					 GSM_CAUSE_ACT_REJ_GGSN);
		goto reject;
	}

	if (pctx->mm->ran_type == MM_CTX_T_GERAN_Gb) {
		/* Activate the SNDCP layer */
		sndcp_sm_activate_ind(&pctx->mm->gb.llme->lle[pctx->sapi], pctx->nsapi);


		return send_act_pdp_cont_acc(pctx);
	} else {
		/* Activate a radio bearer */
		iu_rab_act_ps(pctx);
		return 0;
	}

reject:
	/*
	 * In case of a timeout pdp will be NULL but we have a valid pointer
	 * in pctx->lib. For other rejects pctx->lib and pdp might be the
	 * same.
	 */
	pctx->state = PDP_STATE_NONE;
	if (pctx->lib && pctx->lib != pdp)
		pdp_freepdp(pctx->lib);
	pctx->lib = NULL;

	if (pdp)
		pdp_freepdp(pdp);
	/* Send PDP CTX ACT REJ to MS */
	gsm48_tx_gsm_act_pdp_rej(pctx->mm, pctx->ti, reject_cause,
					0, NULL);
	sgsn_pdp_ctx_free(pctx);

	return EOF;
}

/* Callback for RAB assignment response */
int sgsn_ranap_rab_ass_resp(struct sgsn_mm_ctx *ctx, RANAP_RAB_SetupOrModifiedItemIEs_t *setup_ies)
{
	uint8_t rab_id;
	struct sgsn_pdp_ctx *pdp = NULL;
	uint32_t gtp_tei;
	RANAP_RAB_SetupOrModifiedItem_t *item = &setup_ies->raB_SetupOrModifiedItem;

	rab_id = item->rAB_ID.buf[0];

	if (item->iuTransportAssociation->present == RANAP_IuTransportAssociation_PR_gTP_TEI) {
		gtp_tei = asn1str_to_u32(&item->iuTransportAssociation->choice.gTP_TEI);
		pdp = sgsn_pdp_ctx_by_tei(ctx, gtp_tei);
	}

	if (!pdp) {
		return -1;
	}

	if (item->transportLayerAddress) {

		LOGPC(DRANAP, LOGL_INFO, " Setup: (%u/%s)", rab_id, osmo_hexdump(item->transportLayerAddress->buf,
								     item->transportLayerAddress->size));
		memcpy(pdp->lib->gsnlu.v, &item->transportLayerAddress->buf[3], 4);
		gtp_update_context(pdp->ggsn->gsn, pdp->lib, pdp, &pdp->lib->hisaddr0);

	}

	send_act_pdp_cont_acc(pdp);
	return 0;

}

/* Confirmation of a PDP Context Delete */
static int delete_pdp_conf(struct pdp_t *pdp, void *cbp, int cause)
{
	struct sgsn_signal_data sig_data;
	struct sgsn_pdp_ctx *pctx = cbp;
	int rc = 0;

	LOGPDPCTXP(LOGL_INFO, pctx, "Received DELETE PDP CTX CONF, cause=%d(%s)\n",
		cause, get_value_string(gtp_cause_strs, cause));

	memset(&sig_data, 0, sizeof(sig_data));
	sig_data.pdp = pctx;
	osmo_signal_dispatch(SS_SGSN, S_SGSN_PDP_DEACT, &sig_data);

	if (pctx->mm) {
		if (pctx->mm->ran_type == MM_CTX_T_GERAN_Gb) {
			/* Deactivate the SNDCP layer */
			sndcp_sm_deactivate_ind(&pctx->mm->gb.llme->lle[pctx->sapi], pctx->nsapi);
		} else {
			/* Dectivate a radio bearer */
			/* TODO: Save and use rab_id */
			iu_rab_deact(pctx->mm->iu.ue_ctx, 1);
		}

		/* Confirm deactivation of PDP context to MS */
		rc = gsm48_tx_gsm_deact_pdp_acc(pctx);
	} else {
		LOGPDPCTXP(LOGL_NOTICE, pctx,
			   "Not deactivating SNDCP layer since the MM context "
			   "is not available\n");
	}

	/* unlink the now non-existing library handle from the pdp
	 * context */
	pctx->lib = NULL;

	sgsn_pdp_ctx_free(pctx);

	return rc;
}

/* Confirmation of an GTP ECHO request */
static int echo_conf(struct pdp_t *pdp, void *cbp, int recovery)
{
	if (recovery < 0) {
		LOGP(DGPRS, LOGL_NOTICE, "GTP Echo Request timed out\n");
		/* FIXME: if version == 1, retry with version 0 */
	} else {
		DEBUGP(DGPRS, "GTP Rx Echo Response\n");
	}
	return 0;
}

/* Any message received by GGSN contains a recovery IE */
static int cb_recovery(struct sockaddr_in *peer, uint8_t recovery)
{
	struct sgsn_ggsn_ctx *ggsn;
	
	ggsn = sgsn_ggsn_ctx_by_addr(&peer->sin_addr);
	if (!ggsn) {
		LOGP(DGPRS, LOGL_NOTICE, "Received Recovery IE for unknown GGSN\n");
		return -EINVAL;
	}

	if (ggsn->remote_restart_ctr == -1) {
		/* First received ECHO RESPONSE, note the restart ctr */
		ggsn->remote_restart_ctr = recovery;
	} else if (ggsn->remote_restart_ctr != recovery) {
		/* counter has changed (GGSN restart): release all PDP */
		LOGP(DGPRS, LOGL_NOTICE, "GGSN recovery (%u->%u), "
		     "releasing all PDP contexts\n",
		     ggsn->remote_restart_ctr, recovery);
		ggsn->remote_restart_ctr = recovery;
		drop_all_pdp_for_ggsn(ggsn);
	}
	return 0;
}

/* libgtp callback for confirmations */
static int cb_conf(int type, int cause, struct pdp_t *pdp, void *cbp)
{
	DEBUGP(DGPRS, "libgtp cb_conf(type=%d, cause=%d, pdp=%p, cbp=%p)\n",
		type, cause, pdp, cbp);

	if (cause == EOF)
		LOGP(DGPRS, LOGL_ERROR, "libgtp EOF (type=%u, pdp=%p, cbp=%p)\n",
			type, pdp, cbp);

	switch (type) {
	case GTP_ECHO_REQ:
		/* libgtp hands us the RECOVERY number instead of a cause */
		return echo_conf(pdp, cbp, cause);
	case GTP_CREATE_PDP_REQ:
		return create_pdp_conf(pdp, cbp, cause);
	case GTP_DELETE_PDP_REQ:
		return delete_pdp_conf(pdp, cbp, cause);
	default:
		break;
	}
	return 0;
}

/* Called whenever a PDP context is deleted for any reason */
static int cb_delete_context(struct pdp_t *pdp)
{
	LOGP(DGPRS, LOGL_INFO, "PDP Context was deleted\n");
	return 0;
}

/* Called when we receive a Version Not Supported message */
static int cb_unsup_ind(struct sockaddr_in *peer)
{
	LOGP(DGPRS, LOGL_INFO, "GTP Version not supported Indication "
		"from %s:%u\n", inet_ntoa(peer->sin_addr),
		ntohs(peer->sin_port));
	return 0;
}

/* Called when we receive a Supported Ext Headers Notification */
static int cb_extheader_ind(struct sockaddr_in *peer)
{
	LOGP(DGPRS, LOGL_INFO, "GTP Supported Ext Headers Noficiation "
		"from %s:%u\n", inet_ntoa(peer->sin_addr),
		ntohs(peer->sin_port));
	return 0;
}

/* Called whenever we recive a DATA packet */
static int cb_data_ind(struct pdp_t *lib, void *packet, unsigned int len)
{
	struct bssgp_paging_info pinfo;
	struct sgsn_pdp_ctx *pdp;
	struct sgsn_mm_ctx *mm;
	struct msgb *msg;
	uint8_t *ud;

	DEBUGP(DGPRS, "GTP DATA IND from GGSN, length=%u\n", len);

	pdp = lib->priv;
	if (!pdp) {
		LOGP(DGPRS, LOGL_NOTICE,
		     "GTP DATA IND from GGSN for unknown PDP\n");
		return -EIO;
	}
	mm = pdp->mm;
	if (!mm) {
		LOGP(DGPRS, LOGL_ERROR,
		     "PDP context (imsi=%s) without MM context!\n", mm->imsi);
		return -EIO;
	}

	msg = msgb_alloc_headroom(len+256, 128, "GTP->SNDCP");
	ud = msgb_put(msg, len);
	memcpy(ud, packet, len);

	msgb_tlli(msg) = mm->gb.tlli;
	msgb_bvci(msg) = mm->gb.bvci;
	msgb_nsei(msg) = mm->gb.nsei;

	switch (mm->mm_state) {
	case GMM_REGISTERED_SUSPENDED:
		/* initiate PS PAGING procedure */
		memset(&pinfo, 0, sizeof(pinfo));
		pinfo.mode = BSSGP_PAGING_PS;
		pinfo.scope = BSSGP_PAGING_BVCI;
		pinfo.bvci = mm->gb.bvci;
		pinfo.imsi = mm->imsi;
		pinfo.ptmsi = &mm->p_tmsi;
		pinfo.drx_params = mm->drx_parms;
		pinfo.qos[0] = 0; // FIXME
		bssgp_tx_paging(mm->gb.nsei, 0, &pinfo);
		rate_ctr_inc(&mm->ctrg->ctr[GMM_CTR_PAGING_PS]);
		/* FIXME: queue the packet we received from GTP */
		break;
	case GMM_REGISTERED_NORMAL:
		break;
	default:
		LOGP(DGPRS, LOGL_ERROR, "GTP DATA IND for TLLI %08X in state "
			"%u\n", mm->gb.tlli, mm->mm_state);
		msgb_free(msg);
		return -1;
	}

	rate_ctr_inc(&pdp->ctrg->ctr[PDP_CTR_PKTS_UDATA_OUT]);
	rate_ctr_add(&pdp->ctrg->ctr[PDP_CTR_BYTES_UDATA_OUT], len);
	rate_ctr_inc(&mm->ctrg->ctr[GMM_CTR_PKTS_UDATA_OUT]);
	rate_ctr_add(&mm->ctrg->ctr[GMM_CTR_BYTES_UDATA_OUT], len);

	/* It is easier to have a global count */
	pdp->cdr_bytes_out += len;

	return sndcp_unitdata_req(msg, &mm->gb.llme->lle[pdp->sapi],
				  pdp->nsapi, mm);
}

/* Called by SNDCP when it has received/re-assembled a N-PDU */
int sgsn_rx_sndcp_ud_ind(struct gprs_ra_id *ra_id, int32_t tlli, uint8_t nsapi,
			 struct msgb *msg, uint32_t npdu_len, uint8_t *npdu)
{
	struct sgsn_mm_ctx *mmctx;
	struct sgsn_pdp_ctx *pdp;

	/* look-up the MM context for this message */
	mmctx = sgsn_mm_ctx_by_tlli(tlli, ra_id);
	if (!mmctx) {
		LOGP(DGPRS, LOGL_ERROR,
			"Cannot find MM CTX for TLLI %08x\n", tlli);
		return -EIO;
	}
	/* look-up the PDP context for this message */
	pdp = sgsn_pdp_ctx_by_nsapi(mmctx, nsapi);
	if (!pdp) {
		LOGP(DGPRS, LOGL_ERROR, "Cannot find PDP CTX for "
			"TLLI=%08x, NSAPI=%u\n", tlli, nsapi);
		return -EIO;
	}
	if (!pdp->lib) {
		LOGP(DGPRS, LOGL_ERROR, "PDP CTX without libgtp\n");
		return -EIO;
	}

	rate_ctr_inc(&pdp->ctrg->ctr[PDP_CTR_PKTS_UDATA_IN]);
	rate_ctr_add(&pdp->ctrg->ctr[PDP_CTR_BYTES_UDATA_IN], npdu_len);
	rate_ctr_inc(&mmctx->ctrg->ctr[GMM_CTR_PKTS_UDATA_IN]);
	rate_ctr_add(&mmctx->ctrg->ctr[GMM_CTR_BYTES_UDATA_IN], npdu_len);

	/* It is easier to have a global count */
	pdp->cdr_bytes_in += npdu_len;

	return gtp_data_req(pdp->ggsn->gsn, pdp->lib, npdu, npdu_len);
}

/* libgtp select loop integration */
static int sgsn_gtp_fd_cb(struct osmo_fd *fd, unsigned int what)
{
	struct sgsn_instance *sgi = fd->data;
	int rc;

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

	switch (fd->priv_nr) {
	case 0:
		rc = gtp_decaps0(sgi->gsn);
		break;
	case 1:
		rc = gtp_decaps1c(sgi->gsn);
		break;
	case 2:
		rc = gtp_decaps1u(sgi->gsn);
		break;
	default:
		rc = -EINVAL;
		break;
	}
	return rc;
}

static void sgsn_gtp_tmr_start(struct sgsn_instance *sgi)
{
	struct timeval next;

	/* Retrieve next retransmission as struct timeval */
	gtp_retranstimeout(sgi->gsn, &next);

	/* re-schedule the timer */
	osmo_timer_schedule(&sgi->gtp_timer, next.tv_sec, next.tv_usec/1000);
}

/* timer callback for libgtp retransmissions and ping */
static void sgsn_gtp_tmr_cb(void *data)
{
	struct sgsn_instance *sgi = data;

	/* Do all the retransmissions as needed */
	gtp_retrans(sgi->gsn);

	sgsn_gtp_tmr_start(sgi);
}

int sgsn_gtp_init(struct sgsn_instance *sgi)
{
	int rc;
	struct gsn_t *gsn;

	rc = gtp_new(&sgi->gsn, sgi->cfg.gtp_statedir,
		     &sgi->cfg.gtp_listenaddr.sin_addr, GTP_MODE_SGSN);
	if (rc) {
		LOGP(DGPRS, LOGL_ERROR, "Failed to create GTP: %d\n", rc);
		return rc;
	}
	gsn = sgi->gsn;

	sgi->gtp_fd0.fd = gsn->fd0;
	sgi->gtp_fd0.priv_nr = 0;
	sgi->gtp_fd0.data = sgi;
	sgi->gtp_fd0.when = BSC_FD_READ;
	sgi->gtp_fd0.cb = sgsn_gtp_fd_cb;
	rc = osmo_fd_register(&sgi->gtp_fd0);
	if (rc < 0)
		return rc;

	sgi->gtp_fd1c.fd = gsn->fd1c;
	sgi->gtp_fd1c.priv_nr = 1;
	sgi->gtp_fd1c.data = sgi;
	sgi->gtp_fd1c.when = BSC_FD_READ;
	sgi->gtp_fd1c.cb = sgsn_gtp_fd_cb;
	rc = osmo_fd_register(&sgi->gtp_fd1c);
	if (rc < 0) {
		osmo_fd_unregister(&sgi->gtp_fd0);
		return rc;
	}

	sgi->gtp_fd1u.fd = gsn->fd1u;
	sgi->gtp_fd1u.priv_nr = 2;
	sgi->gtp_fd1u.data = sgi;
	sgi->gtp_fd1u.when = BSC_FD_READ;
	sgi->gtp_fd1u.cb = sgsn_gtp_fd_cb;
	rc = osmo_fd_register(&sgi->gtp_fd1u);
	if (rc < 0) {
		osmo_fd_unregister(&sgi->gtp_fd0);
		osmo_fd_unregister(&sgi->gtp_fd1c);
		return rc;
	}

	/* Start GTP re-transmission timer */
	sgi->gtp_timer.cb = sgsn_gtp_tmr_cb;
	sgi->gtp_timer.data = sgi;
	sgsn_gtp_tmr_start(sgi);

	/* Register callbackcs with libgtp */
	gtp_set_cb_delete_context(gsn, cb_delete_context);
	gtp_set_cb_conf(gsn, cb_conf);
	gtp_set_cb_recovery(gsn, cb_recovery);
	gtp_set_cb_data_ind(gsn, cb_data_ind);
	gtp_set_cb_unsup_ind(gsn, cb_unsup_ind);
	gtp_set_cb_extheader_ind(gsn, cb_extheader_ind);

	return 0;
}