summaryrefslogtreecommitdiffstats
path: root/openbsc/src/gprs/gprs_sgsn.c
blob: c346201837d2131b8d86c57884b801b1e18ea99e (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
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
/* GPRS SGSN functionality */

/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
 *
 * 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 <stdint.h>

#include <osmocom/core/linuxlist.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/rate_ctr.h>
#include <osmocom/core/stats.h>
#include <osmocom/core/backtrace.h>
#include <osmocom/gprs/gprs_ns.h>
#include <osmocom/gprs/gprs_bssgp.h>

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

#include <pdp.h>

#include <time.h>

#include <openssl/rand.h>

#define GPRS_LLME_CHECK_TICK 30

extern struct sgsn_instance *sgsn;

LLIST_HEAD(sgsn_mm_ctxts);
LLIST_HEAD(sgsn_ggsn_ctxts);
LLIST_HEAD(sgsn_apn_ctxts);
LLIST_HEAD(sgsn_pdp_ctxts);

static const struct rate_ctr_desc mmctx_ctr_description[] = {
	{ "sign.packets.in",	"Signalling Messages ( In)" },
	{ "sign.packets.out",	"Signalling Messages (Out)" },
	{ "udata.packets.in",	"User Data  Messages ( In)" },
	{ "udata.packets.out",	"User Data  Messages (Out)" },
	{ "udata.bytes.in",	"User Data  Bytes    ( In)" },
	{ "udata.bytes.out",	"User Data  Bytes    (Out)" },
	{ "pdp_ctx_act",	"PDP Context Activations  " },
	{ "suspend",		"SUSPEND Count            " },
	{ "paging.ps",		"Paging Packet Switched   " },
	{ "paging.cs",		"Paging Circuit Switched  " },
	{ "ra_update",		"Routing Area Update      " },
};

static const struct rate_ctr_group_desc mmctx_ctrg_desc = {
	.group_name_prefix = "sgsn.mmctx",
	.group_description = "SGSN MM Context Statistics",
	.num_ctr = ARRAY_SIZE(mmctx_ctr_description),
	.ctr_desc = mmctx_ctr_description,
	.class_id = OSMO_STATS_CLASS_SUBSCRIBER,
};

static const struct rate_ctr_desc pdpctx_ctr_description[] = {
	{ "udata.packets.in",	"User Data  Messages ( In)" },
	{ "udata.packets.out",	"User Data  Messages (Out)" },
	{ "udata.bytes.in",	"User Data  Bytes    ( In)" },
	{ "udata.bytes.out",	"User Data  Bytes    (Out)" },
};

static const struct rate_ctr_group_desc pdpctx_ctrg_desc = {
	.group_name_prefix = "sgsn.pdpctx",
	.group_description = "SGSN PDP Context Statistics",
	.num_ctr = ARRAY_SIZE(pdpctx_ctr_description),
	.ctr_desc = pdpctx_ctr_description,
	.class_id = OSMO_STATS_CLASS_SUBSCRIBER,
};

/* look-up a SGSN MM context based on TLLI + RAI */
struct sgsn_mm_ctx *sgsn_mm_ctx_by_ue_ctx(const void *uectx)
{
	struct sgsn_mm_ctx *ctx;

	llist_for_each_entry(ctx, &sgsn_mm_ctxts, list) {
		if (ctx->ran_type == MM_CTX_T_UTRAN_Iu && uectx == ctx->iu.ue_ctx)
			return ctx;
	}

	return NULL;
}

/* look-up a SGSN MM context based on TLLI + RAI */
struct sgsn_mm_ctx *sgsn_mm_ctx_by_tlli(uint32_t tlli,
					const struct gprs_ra_id *raid)
{
	struct sgsn_mm_ctx *ctx;

	llist_for_each_entry(ctx, &sgsn_mm_ctxts, list) {
		if ((tlli == ctx->gb.tlli || tlli == ctx->gb.tlli_new) &&
		    gprs_ra_id_equals(raid, &ctx->ra))
			return ctx;
	}

	return NULL;
}

struct sgsn_mm_ctx *sgsn_mm_ctx_by_tlli_and_ptmsi(uint32_t tlli,
					const struct gprs_ra_id *raid)
{
	struct sgsn_mm_ctx *ctx;
	int tlli_type;

	/* TODO: Also check the P_TMSI signature to be safe. That signature
	 * should be different (at least with a sufficiently high probability)
	 * after SGSN restarts and for multiple SGSN instances.
	 */

	tlli_type = gprs_tlli_type(tlli);
	if (tlli_type != TLLI_FOREIGN && tlli_type != TLLI_LOCAL)
		return NULL;

	llist_for_each_entry(ctx, &sgsn_mm_ctxts, list) {
		if ((gprs_tmsi2tlli(ctx->p_tmsi, tlli_type) == tlli ||
		     gprs_tmsi2tlli(ctx->p_tmsi_old, tlli_type) == tlli) &&
		    gprs_ra_id_equals(raid, &ctx->ra))
			return ctx;
	}

	return NULL;
}

struct sgsn_mm_ctx *sgsn_mm_ctx_by_ptmsi(uint32_t p_tmsi)
{
	struct sgsn_mm_ctx *ctx;

	llist_for_each_entry(ctx, &sgsn_mm_ctxts, list) {
		if (p_tmsi == ctx->p_tmsi ||
		    (ctx->p_tmsi_old && ctx->p_tmsi_old == p_tmsi))
			return ctx;
	}
	return NULL;
}

struct sgsn_mm_ctx *sgsn_mm_ctx_by_imsi(const char *imsi)
{
	struct sgsn_mm_ctx *ctx;

	llist_for_each_entry(ctx, &sgsn_mm_ctxts, list) {
		if (!strcmp(imsi, ctx->imsi))
			return ctx;
	}
	return NULL;

}

/* Allocate a new SGSN MM context */
struct sgsn_mm_ctx *sgsn_mm_ctx_alloc(uint32_t tlli,
					const struct gprs_ra_id *raid)
{
	struct sgsn_mm_ctx *ctx;

	ctx = talloc_zero(tall_bsc_ctx, struct sgsn_mm_ctx);
	if (!ctx)
		return NULL;

	memcpy(&ctx->ra, raid, sizeof(ctx->ra));
	ctx->ran_type = MM_CTX_T_GERAN_Gb;
	ctx->gb.tlli = tlli;
	ctx->mm_state = GMM_DEREGISTERED;
	ctx->auth_triplet.key_seq = GSM_KEY_SEQ_INVAL;
	ctx->ctrg = rate_ctr_group_alloc(ctx, &mmctx_ctrg_desc, tlli);
	INIT_LLIST_HEAD(&ctx->pdp_list);

	llist_add(&ctx->list, &sgsn_mm_ctxts);

	return ctx;
}

/* Allocate a new SGSN MM context */
struct sgsn_mm_ctx *sgsn_mm_ctx_alloc_iu(void *uectx)
{
	struct sgsn_mm_ctx *ctx;

	ctx = talloc_zero(tall_bsc_ctx, struct sgsn_mm_ctx);
	if (!ctx)
		return NULL;

	ctx->ran_type = MM_CTX_T_UTRAN_Iu;
	ctx->iu.ue_ctx = uectx;
	ctx->iu.new_key = 1;
	ctx->mm_state = GMM_DEREGISTERED;
	ctx->auth_triplet.key_seq = GSM_KEY_SEQ_INVAL;
	ctx->ctrg = rate_ctr_group_alloc(ctx, &mmctx_ctrg_desc, 0);
	INIT_LLIST_HEAD(&ctx->pdp_list);

	llist_add(&ctx->list, &sgsn_mm_ctxts);

	return ctx;
}


/* this is a hard _free_ function, it doesn't clean up the PDP contexts
 * in libgtp! */
static void sgsn_mm_ctx_free(struct sgsn_mm_ctx *mm)
{
	struct sgsn_pdp_ctx *pdp, *pdp2;

	/* Unlink from global list of MM contexts */
	llist_del(&mm->list);

	/* Free all PDP contexts */
	llist_for_each_entry_safe(pdp, pdp2, &mm->pdp_list, list)
		sgsn_pdp_ctx_free(pdp);

	rate_ctr_group_free(mm->ctrg);

	talloc_free(mm);
}

void sgsn_mm_ctx_cleanup_free(struct sgsn_mm_ctx *mm)
{
	struct gprs_llc_llme *llme = mm->gb.llme;
	uint32_t tlli = mm->gb.tlli;
	struct sgsn_pdp_ctx *pdp, *pdp2;
	struct sgsn_signal_data sig_data;
	enum sgsn_ran_type ran_type;

	/* Forget about ongoing look-ups */
	if (mm->ggsn_lookup) {
		LOGMMCTXP(LOGL_NOTICE, mm,
			"Cleaning mmctx with on-going query.\n");
		mm->ggsn_lookup->mmctx = NULL;
		mm->ggsn_lookup = NULL;
	}

	/* delete all existing PDP contexts for this MS */
	llist_for_each_entry_safe(pdp, pdp2, &mm->pdp_list, list) {
		LOGMMCTXP(LOGL_NOTICE, mm,
			  "Dropping PDP context for NSAPI=%u\n", pdp->nsapi);
		sgsn_pdp_ctx_terminate(pdp);
	}

	if (osmo_timer_pending(&mm->timer)) {
		LOGMMCTXP(LOGL_INFO, mm, "Cancelling MM timer %u\n", mm->T);
		osmo_timer_del(&mm->timer);
	}

	memset(&sig_data, 0, sizeof(sig_data));
	sig_data.mm = mm;
	osmo_signal_dispatch(SS_SGSN, S_SGSN_MM_FREE, &sig_data);


	/* Detach from subscriber which is possibly freed then */
	if (mm->subscr) {
		struct gsm_subscriber *subscr = subscr_get(mm->subscr);
		gprs_subscr_cleanup(subscr);
		subscr_put(subscr);
	}

	ran_type = mm->ran_type;

	sgsn_mm_ctx_free(mm);
	mm = NULL;

	if (ran_type == MM_CTX_T_GERAN_Gb) {
		/* TLLI unassignment, must be called after sgsn_mm_ctx_free */
		gprs_llgmm_assign(llme, tlli, 0xffffffff, GPRS_ALGO_GEA0, NULL);
	}
}


/* look up PDP context by MM context and NSAPI */
struct sgsn_pdp_ctx *sgsn_pdp_ctx_by_nsapi(const struct sgsn_mm_ctx *mm,
					   uint8_t nsapi)
{
	struct sgsn_pdp_ctx *pdp;

	llist_for_each_entry(pdp, &mm->pdp_list, list) {
		if (pdp->nsapi == nsapi)
			return pdp;
	}
	return NULL;
}

/* look up PDP context by MM context and transaction ID */
struct sgsn_pdp_ctx *sgsn_pdp_ctx_by_tid(const struct sgsn_mm_ctx *mm,
					 uint8_t tid)
{
	struct sgsn_pdp_ctx *pdp;

	llist_for_each_entry(pdp, &mm->pdp_list, list) {
		if (pdp->ti == tid)
			return pdp;
	}
	return NULL;
}

/* you don't want to use this directly, call sgsn_create_pdp_ctx() */
struct sgsn_pdp_ctx *sgsn_pdp_ctx_alloc(struct sgsn_mm_ctx *mm,
					uint8_t nsapi)
{
	struct sgsn_pdp_ctx *pdp;

	pdp = sgsn_pdp_ctx_by_nsapi(mm, nsapi);
	if (pdp)
		return NULL;

	pdp = talloc_zero(tall_bsc_ctx, struct sgsn_pdp_ctx);
	if (!pdp)
		return NULL;

	pdp->mm = mm;
	pdp->nsapi = nsapi;
	pdp->ctrg = rate_ctr_group_alloc(pdp, &pdpctx_ctrg_desc, nsapi);
	llist_add(&pdp->list, &mm->pdp_list);
	llist_add(&pdp->g_list, &sgsn_pdp_ctxts);

	return pdp;
}

/*
 * This function will not trigger any GSM DEACT PDP ACK messages, so you
 * probably want to call sgsn_delete_pdp_ctx() instead if the connection
 * isn't detached already.
 */
void sgsn_pdp_ctx_terminate(struct sgsn_pdp_ctx *pdp)
{
	struct sgsn_signal_data sig_data;

	OSMO_ASSERT(pdp->mm != NULL);

	/* There might still be pending callbacks in libgtp. So the parts of
	 * this object relevant to GTP need to remain intact in this case. */

	LOGPDPCTXP(LOGL_INFO, pdp, "Forcing release of PDP context\n");

	if (pdp->mm->ran_type == MM_CTX_T_GERAN_Gb) {
		/* Force the deactivation of the SNDCP layer */
		sndcp_sm_deactivate_ind(&pdp->mm->gb.llme->lle[pdp->sapi], pdp->nsapi);
	}

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

	/* Detach from MM context */
	llist_del(&pdp->list);
	pdp->mm = NULL;

	sgsn_delete_pdp_ctx(pdp);
}

/*
 * Don't call this function directly unless you know what you are doing.
 * In normal conditions use sgsn_delete_pdp_ctx and in unspecified or
 * implementation dependent abnormal ones sgsn_pdp_ctx_terminate.
 */
void sgsn_pdp_ctx_free(struct sgsn_pdp_ctx *pdp)
{
	struct sgsn_signal_data sig_data;

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

	rate_ctr_group_free(pdp->ctrg);
	if (pdp->mm)
		llist_del(&pdp->list);
	llist_del(&pdp->g_list);

	/* _if_ we still have a library handle, at least set it to NULL
	 * to avoid any dereferences of the now-deleted PDP context from
	 * sgsn_libgtp:cb_data_ind() */
	if (pdp->lib) {
		struct pdp_t *lib = pdp->lib;
		LOGPDPCTXP(LOGL_NOTICE, pdp, "freeing PDP context that still "
		     "has a libgtp handle attached to it, this shouldn't "
		     "happen!\n");
		osmo_generate_backtrace();
		lib->priv = NULL;
	}

	if (pdp->destroy_ggsn)
		sgsn_ggsn_ctx_free(pdp->ggsn);
	talloc_free(pdp);
}

/* GGSN contexts */

struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_alloc(uint32_t id)
{
	struct sgsn_ggsn_ctx *ggc;

	ggc = talloc_zero(tall_bsc_ctx, struct sgsn_ggsn_ctx);
	if (!ggc)
		return NULL;

	ggc->id = id;
	ggc->gtp_version = 1;
	ggc->remote_restart_ctr = -1;
	/* if we are called from config file parse, this gsn doesn't exist yet */
	ggc->gsn = sgsn->gsn;
	llist_add(&ggc->list, &sgsn_ggsn_ctxts);

	return ggc;
}

void sgsn_ggsn_ctx_free(struct sgsn_ggsn_ctx *ggc)
{
	llist_del(&ggc->list);
	talloc_free(ggc);
}

struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_by_id(uint32_t id)
{
	struct sgsn_ggsn_ctx *ggc;

	llist_for_each_entry(ggc, &sgsn_ggsn_ctxts, list) {
		if (id == ggc->id)
			return ggc;
	}
	return NULL;
}

struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_by_addr(struct in_addr *addr)
{
	struct sgsn_ggsn_ctx *ggc;

	llist_for_each_entry(ggc, &sgsn_ggsn_ctxts, list) {
		if (!memcmp(addr, &ggc->remote_addr, sizeof(*addr)))
			return ggc;
	}
	return NULL;
}


struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_find_alloc(uint32_t id)
{
	struct sgsn_ggsn_ctx *ggc;

	ggc = sgsn_ggsn_ctx_by_id(id);
	if (!ggc)
		ggc = sgsn_ggsn_ctx_alloc(id);
	return ggc;
}

/* APN contexts */

static struct apn_ctx *sgsn_apn_ctx_alloc(const char *ap_name, const char *imsi_prefix)
{
	struct apn_ctx *actx;

	actx = talloc_zero(tall_bsc_ctx, struct apn_ctx);
	if (!actx)
		return NULL;
	actx->name = talloc_strdup(actx, ap_name);
	actx->imsi_prefix = talloc_strdup(actx, imsi_prefix);

	llist_add_tail(&actx->list, &sgsn_apn_ctxts);

	return actx;
}

void sgsn_apn_ctx_free(struct apn_ctx *actx)
{
	llist_del(&actx->list);
	talloc_free(actx);
}

struct apn_ctx *sgsn_apn_ctx_match(const char *name, const char *imsi)
{
	struct apn_ctx *actx;
	struct apn_ctx *found_actx = NULL;
	size_t imsi_prio = 0;
	size_t name_prio = 0;
	size_t name_req_len = strlen(name);

	llist_for_each_entry(actx, &sgsn_apn_ctxts, list) {
		size_t name_ref_len, imsi_ref_len;
		const char *name_ref_start, *name_match_start;

		imsi_ref_len = strlen(actx->imsi_prefix);
		if (strncmp(actx->imsi_prefix, imsi, imsi_ref_len) != 0)
			continue;

		if (imsi_ref_len < imsi_prio)
			continue;

		/* IMSI matches */

		name_ref_start = &actx->name[0];
		if (name_ref_start[0] == '*') {
			/* Suffix match */
			name_ref_start += 1;
			name_ref_len = strlen(name_ref_start);
			if (name_ref_len > name_req_len)
				continue;
		} else {
			name_ref_len = strlen(name_ref_start);
			if (name_ref_len != name_req_len)
				continue;
		}

		name_match_start = name + (name_req_len - name_ref_len);
		if (strcasecmp(name_match_start, name_ref_start) != 0)
			continue;

		/* IMSI and name match */

		if (imsi_ref_len == imsi_prio && name_ref_len < name_prio)
			/* Lower priority, skip */
			continue;

		imsi_prio = imsi_ref_len;
		name_prio = name_ref_len;
		found_actx = actx;
	}
	return found_actx;
}

struct apn_ctx *sgsn_apn_ctx_by_name(const char *name, const char *imsi_prefix)
{
	struct apn_ctx *actx;

	llist_for_each_entry(actx, &sgsn_apn_ctxts, list) {
		if (strcasecmp(name, actx->name) == 0 &&
		    strcasecmp(imsi_prefix, actx->imsi_prefix) == 0)
			return actx;
	}
	return NULL;
}

struct apn_ctx *sgsn_apn_ctx_find_alloc(const char *name, const char *imsi_prefix)
{
	struct apn_ctx *actx;

	actx = sgsn_apn_ctx_by_name(name, imsi_prefix);
	if (!actx)
		actx = sgsn_apn_ctx_alloc(name, imsi_prefix);

	return actx;
}

uint32_t sgsn_alloc_ptmsi(void)
{
	struct sgsn_mm_ctx *mm;
	uint32_t ptmsi;
	int max_retries = 100;

restart:
	if (RAND_bytes((uint8_t *) &ptmsi, sizeof(ptmsi)) != 1)
		goto failed;

	/* Enforce that the 2 MSB are set without loosing the distance between
	 * identical values. Since rand() has no duplicate values within a
	 * period (because the size of the state is the same like the size of
	 * the random value), this leads to a distance of period/4 when the
	 * distribution of the 2 MSB is uniform. This approach fails with a
	 * probability of (3/4)^max_retries, only 1% of the approaches will
	 * need more than 16 numbers (even distribution assumed).
	 *
	 * Alternatively, a freeze list could be used if another PRNG is used
	 * or when this approach proves to be not sufficient.
	 */
	if (ptmsi >= 0xC0000000) {
		if (!max_retries--)
			goto failed;
		goto restart;
	}
	ptmsi |= 0xC0000000;

	if (ptmsi == GSM_RESERVED_TMSI) {
		if (!max_retries--)
			goto failed;
		goto restart;
	}

	llist_for_each_entry(mm, &sgsn_mm_ctxts, list) {
		if (mm->p_tmsi == ptmsi) {
			if (!max_retries--)
				goto failed;
			goto restart;
		}
	}

	return ptmsi;

failed:
	LOGP(DGPRS, LOGL_ERROR, "Failed to allocate a P-TMSI\n");
	return GSM_RESERVED_TMSI;
}

static void drop_one_pdp(struct sgsn_pdp_ctx *pdp)
{
	if (pdp->mm->mm_state == GMM_REGISTERED_NORMAL)
		gsm48_tx_gsm_deact_pdp_req(pdp, GSM_CAUSE_NET_FAIL);
	else  {
		/* FIXME: GPRS paging in case MS is SUSPENDED */
		LOGPDPCTXP(LOGL_NOTICE, pdp, "Hard-dropping PDP ctx due to GGSN "
			"recovery\n");
		/* FIXME: how to tell this to libgtp? */
		sgsn_pdp_ctx_free(pdp);
	}
}

/* High-level function to be called in case a GGSN has disappeared or
 * otherwise lost state (recovery procedure) */
int drop_all_pdp_for_ggsn(struct sgsn_ggsn_ctx *ggsn)
{
	struct sgsn_mm_ctx *mm;
	int num = 0;

	llist_for_each_entry(mm, &sgsn_mm_ctxts, list) {
		struct sgsn_pdp_ctx *pdp;
		llist_for_each_entry(pdp, &mm->pdp_list, list) {
			if (pdp->ggsn == ggsn) {
				drop_one_pdp(pdp);
				num++;
			}
		}
	}

	return num;
}

int sgsn_force_reattach_oldmsg(struct msgb *oldmsg)
{
	return gsm0408_gprs_force_reattach_oldmsg(oldmsg);
}

void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx)
{
	OSMO_ASSERT(mmctx != NULL);
	LOGMMCTXP(LOGL_INFO, mmctx, "Subscriber data update\n");

	sgsn_auth_update(mmctx);
}

static void insert_qos(struct tlv_parsed *tp, struct sgsn_subscriber_pdp_data *pdp)
{
	tp->lv[OSMO_IE_GSM_SUB_QOS].len = pdp->qos_subscribed_len;
	tp->lv[OSMO_IE_GSM_SUB_QOS].val = pdp->qos_subscribed;
}

/**
 * The tlv_parsed tp parameter will be modified to insert a
 * OSMO_IE_GSM_SUB_QOS in case the data is available in the
 * PDP context handling.
 */
struct sgsn_ggsn_ctx *sgsn_mm_ctx_find_ggsn_ctx(struct sgsn_mm_ctx *mmctx,
						struct tlv_parsed *tp,
						enum gsm48_gsm_cause *gsm_cause,
						char *out_apn_str)
{
	char req_apn_str[GSM_APN_LENGTH] = {0};
	const struct apn_ctx *apn_ctx = NULL;
	const char *selected_apn_str = NULL;
	struct sgsn_subscriber_pdp_data *pdp;
	struct sgsn_ggsn_ctx *ggsn = NULL;
	int allow_any_apn = 0;

	out_apn_str[0] = '\0';

	if (TLVP_PRESENT(tp, GSM48_IE_GSM_APN)) {
		if (TLVP_LEN(tp, GSM48_IE_GSM_APN) >= GSM_APN_LENGTH - 1) {
			LOGMMCTXP(LOGL_ERROR, mmctx, "APN IE too long\n");
			*gsm_cause = GSM_CAUSE_INV_MAND_INFO;
			return NULL;
		}

		gprs_apn_to_str(req_apn_str,
				TLVP_VAL(tp, GSM48_IE_GSM_APN),
				TLVP_LEN(tp, GSM48_IE_GSM_APN));

		if (strcmp(req_apn_str, "*") == 0)
			req_apn_str[0] = 0;
	}

	if (mmctx->subscr == NULL)
		allow_any_apn = 1;

	if (strlen(req_apn_str) == 0 && !allow_any_apn) {
		/* No specific APN requested, check for an APN that is both
		 * granted and configured */

		llist_for_each_entry(pdp, &mmctx->subscr->sgsn_data->pdp_list, list) {
			if (strcmp(pdp->apn_str, "*") == 0)
			{
				allow_any_apn = 1;
				selected_apn_str = "";
				insert_qos(tp, pdp);
				continue;
			}
			if (!llist_empty(&sgsn_apn_ctxts)) {
				apn_ctx = sgsn_apn_ctx_match(req_apn_str, mmctx->imsi);
				/* Not configured */
				if (apn_ctx == NULL)
					continue;
			}
			insert_qos(tp, pdp);
			selected_apn_str = pdp->apn_str;
			break;
		}
	} else if (!allow_any_apn) {
		/* Check whether the given APN is granted */
		llist_for_each_entry(pdp, &mmctx->subscr->sgsn_data->pdp_list, list) {
			if (strcmp(pdp->apn_str, "*") == 0) {
				insert_qos(tp, pdp);
				selected_apn_str = req_apn_str;
				allow_any_apn = 1;
				continue;
			}
			if (strcasecmp(pdp->apn_str, req_apn_str) == 0) {
				insert_qos(tp, pdp);
				selected_apn_str = req_apn_str;
				break;
			}
		}
	} else if (strlen(req_apn_str) != 0) {
		/* Any APN is allowed */
		selected_apn_str = req_apn_str;
	} else {
		/* Prefer the GGSN associated with the wildcard APN */
		selected_apn_str = "";
	}

	if (!allow_any_apn && selected_apn_str == NULL) {
		/* Access not granted */
		LOGMMCTXP(LOGL_NOTICE, mmctx,
			  "The requested APN '%s' is not allowed\n",
			  req_apn_str);
		*gsm_cause = GSM_CAUSE_REQ_SERV_OPT_NOTSUB;
		return NULL;
	}

	/* copy the selected apn_str */
	if (selected_apn_str)
		strcpy(out_apn_str, selected_apn_str);
	else
		out_apn_str[0] = '\0';

	if (apn_ctx == NULL && selected_apn_str)
		apn_ctx = sgsn_apn_ctx_match(selected_apn_str, mmctx->imsi);

	if (apn_ctx != NULL) {
		ggsn = apn_ctx->ggsn;
	} else if (llist_empty(&sgsn_apn_ctxts)) {
		/* No configuration -> use GGSN 0 */
		ggsn = sgsn_ggsn_ctx_by_id(0);
	} else if (allow_any_apn &&
		   (selected_apn_str == NULL || strlen(selected_apn_str) == 0)) {
		/* No APN given and no default configuration -> Use GGSN 0 */
		ggsn = sgsn_ggsn_ctx_by_id(0);
	} else {
		/* No matching configuration found */
		LOGMMCTXP(LOGL_NOTICE, mmctx,
			  "The selected APN '%s' has not been configured\n",
			  selected_apn_str);
		*gsm_cause = GSM_CAUSE_MISSING_APN;
		return NULL;
	}

	if (!ggsn) {
		LOGMMCTXP(LOGL_NOTICE, mmctx,
			"No static GGSN configured. Selected APN '%s'\n",
			selected_apn_str);
			return NULL;
	}

	LOGMMCTXP(LOGL_INFO, mmctx,
		  "Found GGSN %d for APN '%s' (requested '%s')\n",
		  ggsn->id, selected_apn_str ? selected_apn_str : "---",
		  req_apn_str);

	return ggsn;
}

static void sgsn_llme_cleanup_free(struct gprs_llc_llme *llme)
{
	struct sgsn_mm_ctx *mmctx = NULL;

	llist_for_each_entry(mmctx, &sgsn_mm_ctxts, list) {
		if (llme == mmctx->gb.llme) {
			gsm0408_gprs_access_cancelled(mmctx, SGSN_ERROR_CAUSE_NONE);
			return;
		}
	}

	/* No MM context found */
	LOGP(DGPRS, LOGL_INFO, "Deleting orphaned LLME, TLLI 0x%08x\n",
	     llme->tlli);
	gprs_llgmm_assign(llme, llme->tlli, 0xffffffff, GPRS_ALGO_GEA0, NULL);
}

static void sgsn_llme_check_cb(void *data_)
{
	struct gprs_llc_llme *llme, *llme_tmp;
	struct timespec now_tp;
	time_t now, age;
	time_t max_age = gprs_max_time_to_idle();

	int rc;

	rc = clock_gettime(CLOCK_MONOTONIC, &now_tp);
	OSMO_ASSERT(rc >= 0);
	now = now_tp.tv_sec;

	LOGP(DGPRS, LOGL_DEBUG,
	     "Checking for inactive LLMEs, time = %u\n", (unsigned)now);

	llist_for_each_entry_safe(llme, llme_tmp, &gprs_llc_llmes, list) {
		if (llme->age_timestamp == GPRS_LLME_RESET_AGE)
			llme->age_timestamp = now;

		age = now - llme->age_timestamp;

		if (age > max_age || age < 0) {
			LOGP(DGPRS, LOGL_INFO,
			     "Inactivity timeout for TLLI 0x%08x, age %d\n",
			     llme->tlli, (int)age);
			sgsn_llme_cleanup_free(llme);
		}
	}

	osmo_timer_schedule(&sgsn->llme_timer, GPRS_LLME_CHECK_TICK, 0);
}

void sgsn_inst_init()
{
	sgsn->llme_timer.cb = sgsn_llme_check_cb;
	sgsn->llme_timer.data = NULL;

	osmo_timer_schedule(&sgsn->llme_timer, GPRS_LLME_CHECK_TICK, 0);
}