aboutsummaryrefslogtreecommitdiffstats
path: root/src/osmo-bsc/osmo_bsc_bssap.c
blob: 24a5e3a3e6fc04f934434bd1027203a7ba4e2e44 (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
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
/* GSM 08.08 BSSMAP handling						*/
/* (C) 2009-2012 by Holger Hans Peter Freyther <zecke@selfish.org>
 * (C) 2009-2012 by On-Waves
 * (C) 2017 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 <osmocom/bsc/osmo_bsc.h>
#include <osmocom/bsc/osmo_bsc_grace.h>
#include <osmocom/bsc/osmo_bsc_rf.h>
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/debug.h>
#include <osmocom/bsc/bsc_subscriber.h>
#include <osmocom/bsc/paging.h>
#include <osmocom/bsc/gsm_04_08_utils.h>
#include <osmocom/bsc/bsc_subscr_conn_fsm.h>

#include <osmocom/gsm/protocol/gsm_08_08.h>
#include <osmocom/gsm/gsm0808.h>
#include <osmocom/gsm/gsm0808_utils.h>
#include <osmocom/gsm/gsm48.h>
#include <osmocom/bsc/osmo_bsc_sigtran.h>
#include <osmocom/bsc/osmo_bsc_lcls.h>
#include <osmocom/bsc/a_reset.h>
#include <osmocom/core/byteswap.h>
#include <osmocom/core/fsm.h>

#define IP_V4_ADDR_LEN 4

/*
 * helpers for the assignment command
 */

/* Helper function for match_codec_pref(), looks up a matching permitted speech
 * value for a given msc audio codec pref */
enum gsm0808_permitted_speech audio_support_to_gsm88(struct gsm_audio_support *audio)
{
	if (audio->hr) {
		switch (audio->ver) {
		case 1:
			return GSM0808_PERM_HR1;
			break;
		case 2:
			return GSM0808_PERM_HR2;
			break;
		case 3:
			return GSM0808_PERM_HR3;
			break;
		default:
			LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: hr%d, using hr1 instead\n",
			     audio->ver);
			return GSM0808_PERM_HR1;
		}
	} else {
		switch (audio->ver) {
		case 1:
			return GSM0808_PERM_FR1;
			break;
		case 2:
			return GSM0808_PERM_FR2;
			break;
		case 3:
			return GSM0808_PERM_FR3;
			break;
		default:
			LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: fr%d, using fr1 instead\n",
			     audio->ver);
			return GSM0808_PERM_FR1;
		}
	}
}

/* Helper function for match_codec_pref(), looks up a matching chan mode for
 * a given permitted speech value */
enum gsm48_chan_mode gsm88_to_chan_mode(enum gsm0808_permitted_speech speech)
{
	switch (speech) {
	case GSM0808_PERM_HR1:
	case GSM0808_PERM_FR1:
		return GSM48_CMODE_SPEECH_V1;
		break;
	case GSM0808_PERM_HR2:
	case GSM0808_PERM_FR2:
		return GSM48_CMODE_SPEECH_EFR;
		break;
	case GSM0808_PERM_HR3:
	case GSM0808_PERM_FR3:
		return GSM48_CMODE_SPEECH_AMR;
		break;
	default:
		LOGP(DMSC, LOGL_FATAL,
		     "Unsupported permitted speech selected, assuming AMR as channel mode...\n");
		return GSM48_CMODE_SPEECH_AMR;
	}
}

/* Helper function for match_codec_pref(), tests if a given audio support
 * matches one of the permitted speech settings of the channel type element.
 * The matched permitted speech value is then also compared against the
 * speech codec list. (optional, only relevant for AoIP) */
static bool test_codec_pref(const struct gsm0808_channel_type *ct,
			    const struct gsm0808_speech_codec_list *scl,
			    uint8_t perm_spch)
{
	unsigned int i;
	bool match = false;
	struct gsm0808_speech_codec sc;
	int rc;

	/* Try to finde the given permitted speech value in the
	 * codec list of the channel type element */
	for (i = 0; i < ct->perm_spch_len; i++) {
		if (ct->perm_spch[i] == perm_spch) {
			match = true;
			break;
		}
	}

	/* If we do not have a speech codec list to test against,
	 * we just exit early (will be always the case in non-AoIP networks) */
	if (!scl)
		return match;

	/* If we failed to match until here, there is no
	 * point in testing further */
	if (match == false)
		return false;

	/* Extrapolate speech codec data */
	rc = gsm0808_speech_codec_from_chan_type(&sc, perm_spch);
	if (rc < 0)
		return false;

	/* Try to find extrapolated speech codec data in
	 * the speech codec list */
	for (i = 0; i < scl->len; i++) {
		if (sc.type == scl->codec[i].type)
			return true;
	}

	return false;
}

/*! Helper function for bssmap_handle_assignm_req(), matches the codec
 *  preferences from the MSC with the codec preferences
 *  \param[out] full_rate '1' if full-rate, '0' if half-rate, '-1' if no match
 *  \param[out] chan_mode GSM 04.08 channel mode
 *  \param[in] ct GSM 08.08 channel type
 *  \param[in] scl GSM 08.08 speech codec list
 *  \param[in] msc MSC data [for configuration]
 *  \returns 0 on success, -1 in case no match was found */
static int match_codec_pref(int *full_rate, enum gsm48_chan_mode *chan_mode,
			    const struct gsm0808_channel_type *ct,
			    const struct gsm0808_speech_codec_list *scl,
			    const struct bsc_msc_data *msc)
{
	unsigned int i;
	uint8_t perm_spch;
	bool match = false;

	for (i = 0; i < msc->audio_length; i++) {
		perm_spch = audio_support_to_gsm88(msc->audio_support[i]);
		if (test_codec_pref(ct, scl, perm_spch)) {
			match = true;
			break;
		}
	}

	/* Exit without result, in case no match can be deteched */
	if (!match) {
		*full_rate = -1;
		*chan_mode = GSM48_CMODE_SIGN;
		return -1;
	}

	/* Check if the result is a half or full rate codec */
	if (perm_spch == GSM0808_PERM_HR1 || perm_spch == GSM0808_PERM_HR2
	    || perm_spch == GSM0808_PERM_HR3 || perm_spch == GSM0808_PERM_HR4
	    || perm_spch == GSM0808_PERM_HR6)
		*full_rate = 0;
	else
		*full_rate = 1;

	/* Lookup a channel mode for the selected codec */
	*chan_mode = gsm88_to_chan_mode(perm_spch);

	return 0;
}

static int bssmap_handle_reset_ack(struct bsc_msc_data *msc,
				   struct msgb *msg, unsigned int length)
{
	LOGP(DMSC, LOGL_NOTICE, "RESET ACK from MSC: %s\n",
	     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance),
				 &msc->a.msc_addr));

	/* Inform the FSM that controls the RESET/RESET-ACK procedure
	 * that we have successfully received the reset-ack message */
	a_reset_ack_confirm(msc->a.reset_fsm);

	return 0;
}

/* Handle MSC sided reset */
static int bssmap_handle_reset(struct bsc_msc_data *msc,
			       struct msgb *msg, unsigned int length)
{
	LOGP(DMSC, LOGL_NOTICE, "RESET from MSC: %s\n",
	     osmo_sccp_addr_name(osmo_ss7_instance_find(msc->a.cs7_instance),
				 &msc->a.msc_addr));

	/* Instruct the bsc to close all open sigtran connections and to
	 * close all active channels on the BTS side as well */
	osmo_bsc_sigtran_reset(msc);

	/* Drop all ongoing paging requests that this MSC has created on any BTS */
	paging_flush_network(msc->network, msc);

	/* Inform the MSC that we have received the reset request and
	 * that we acted accordingly */
	osmo_bsc_sigtran_tx_reset_ack(msc);

	return 0;
}

/* Page a subscriber based on TMSI and LAC via the specified BTS.
 * The msc parameter is the MSC which issued the corresponding paging request.
 * Log an error if paging failed. */
static void
page_subscriber(struct bsc_msc_data *msc, struct gsm_bts *bts,
    uint32_t tmsi, uint32_t lac, const char *mi_string, uint8_t chan_needed)
{
	struct bsc_subscr *subscr;
	int ret;

	LOGP(DMSC, LOGL_INFO, "Paging request from MSC BTS: %d IMSI: '%s' TMSI: '0x%x/%u' LAC: 0x%x\n",
	    bts->nr, mi_string, tmsi, tmsi, lac);

	subscr = bsc_subscr_find_or_create_by_imsi(msc->network->bsc_subscribers,
						   mi_string);
	if (!subscr) {
		LOGP(DMSC, LOGL_ERROR, "Paging request failed: Could not allocate subscriber for %s\n", mi_string);
		return;
	}

	subscr->lac = lac;
	subscr->tmsi = tmsi;

	ret = bsc_grace_paging_request(msc->network->bsc_data->rf_ctrl->policy, subscr, chan_needed, msc, bts);
	if (ret == 0)
		LOGP(DMSC, LOGL_ERROR, "Paging request failed: BTS: %d IMSI: '%s' TMSI: '0x%x/%u' LAC: 0x%x\n",
		     bts->nr, mi_string, tmsi, tmsi, lac);

	/* the paging code has grabbed its own references */
	bsc_subscr_put(subscr);
}

static void
page_all_bts(struct bsc_msc_data *msc, uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	struct gsm_bts *bts;
	llist_for_each_entry(bts, &msc->network->bts_list, list)
		page_subscriber(msc, bts, tmsi, GSM_LAC_RESERVED_ALL_BTS, mi_string, chan_needed);
}

static void
page_cgi(struct bsc_msc_data *msc, struct gsm0808_cell_id_list2 *cil,
	 uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	int i;
	for (i = 0; i < cil->id_list_len; i++) {
		struct osmo_cell_global_id *id = &cil->id_list[i].global;
		if (!osmo_plmn_cmp(&id->lai.plmn, &msc->network->plmn)) {
			int paged = 0;
			struct gsm_bts *bts;
			llist_for_each_entry(bts, &msc->network->bts_list, list) {
				if (bts->location_area_code != id->lai.lac)
					continue;
				if (bts->cell_identity != id->cell_identity)
					continue;
				page_subscriber(msc, bts, tmsi, id->lai.lac, mi_string, chan_needed);
				paged = 1;
			}
			if (!paged) {
				LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: BTS with LAC %d and CI %d not found\n",
				     mi_string, id->lai.lac, id->cell_identity);
			}
		} else {
			LOGP(DMSC, LOGL_DEBUG, "Paging IMSI %s: MCC-MNC in Cell Identifier List "
			     "(%s) do not match our network (%s)\n",
			     mi_string, osmo_plmn_name(&id->lai.plmn),
			     osmo_plmn_name2(&msc->network->plmn));
		}
	}
}

static void
page_lac_and_ci(struct bsc_msc_data *msc, struct gsm0808_cell_id_list2 *cil,
	 uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	int i;

	for (i = 0; i < cil->id_list_len; i++) {
		struct osmo_lac_and_ci_id *id = &cil->id_list[i].lac_and_ci;
		int paged = 0;
		struct gsm_bts *bts;
		llist_for_each_entry(bts, &msc->network->bts_list, list) {
			if (bts->location_area_code != id->lac)
				continue;
			if (bts->cell_identity != id->ci)
				continue;
			page_subscriber(msc, bts, tmsi, id->lac, mi_string, chan_needed);
			paged = 1;
		}
		if (!paged) {
			LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: BTS with LAC %d and CI %d not found\n",
			     mi_string, id->lac, id->ci);
		}
	}
}

static void
page_ci(struct bsc_msc_data *msc, struct gsm0808_cell_id_list2 *cil,
	 uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	int i;

	for (i = 0; i < cil->id_list_len; i++) {
		uint16_t ci = cil->id_list[i].ci;
		int paged = 0;
		struct gsm_bts *bts;
		llist_for_each_entry(bts, &msc->network->bts_list, list) {
			if (bts->cell_identity != ci)
				continue;
			page_subscriber(msc, bts, tmsi, GSM_LAC_RESERVED_ALL_BTS, mi_string, chan_needed);
			paged = 1;
		}
		if (!paged) {
			LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: BTS with CI %d not found\n",
			     mi_string, ci);
		}
	}
}

static void
page_lai_and_lac(struct bsc_msc_data *msc, struct gsm0808_cell_id_list2 *cil,
	 uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	int i;

	for (i = 0; i < cil->id_list_len; i++) {
		struct osmo_location_area_id *id = &cil->id_list[i].lai_and_lac;
		if (!osmo_plmn_cmp(&id->plmn, &msc->network->plmn)) {
			int paged = 0;
			struct gsm_bts *bts;
			llist_for_each_entry(bts, &msc->network->bts_list, list) {
				if (bts->location_area_code != id->lac)
					continue;
				page_subscriber(msc, bts, tmsi, id->lac, mi_string, chan_needed);
				paged = 1;
			}
			if (!paged) {
				LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: BTS with LAC %d not found\n",
				     mi_string, id->lac);
			}
		} else {
			LOGP(DMSC, LOGL_DEBUG, "Paging IMSI %s: MCC-MNC in Cell Identifier List "
			     "(%s) do not match our network (%s)\n",
			     mi_string, osmo_plmn_name(&id->plmn),
			     osmo_plmn_name2(&msc->network->plmn));
		}
	}
}

static void
page_lac(struct bsc_msc_data *msc, struct gsm0808_cell_id_list2 *cil,
	 uint32_t tmsi, const char *mi_string, uint8_t chan_needed)
{
	int i;

	for (i = 0; i < cil->id_list_len; i++) {
		uint16_t lac = cil->id_list[i].lac;
		int paged = 0;
		struct gsm_bts *bts;
		llist_for_each_entry(bts, &msc->network->bts_list, list) {
			if (bts->location_area_code != lac)
				continue;
			page_subscriber(msc, bts, tmsi, lac, mi_string, chan_needed);
			paged = 1;
		}
		if (!paged) {
			LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: BTS with LAC %d not found\n",
			     mi_string, lac);
		}
	}
}

/* GSM 08.08 § 3.2.1.19 */
static int bssmap_handle_paging(struct bsc_msc_data *msc,
				struct msgb *msg, unsigned int payload_length)
{
	struct tlv_parsed tp;
	char mi_string[GSM48_MI_SIZE];
	uint32_t tmsi = GSM_RESERVED_TMSI;
	uint8_t data_length;
	int remain;
	const uint8_t *data;
	uint8_t chan_needed = RSL_CHANNEED_ANY;
	struct gsm0808_cell_id_list2 cil;

	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, payload_length - 1, 0, 0);
	remain = payload_length - 1;

	if (!TLVP_PRESENT(&tp, GSM0808_IE_IMSI)) {
		LOGP(DMSC, LOGL_ERROR, "Mandatory IMSI not present.\n");
		return -1;
	} else if ((TLVP_VAL(&tp, GSM0808_IE_IMSI)[0] & GSM_MI_TYPE_MASK) != GSM_MI_TYPE_IMSI) {
		LOGP(DMSC, LOGL_ERROR, "Wrong content in the IMSI\n");
		return -1;
	}
	remain -= TLVP_LEN(&tp, GSM0808_IE_IMSI);

	if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
		LOGP(DMSC, LOGL_ERROR, "Mandatory CELL IDENTIFIER LIST not present.\n");
		return -1;
	}

	if (TLVP_PRESENT(&tp, GSM0808_IE_TMSI) &&
	    TLVP_LEN(&tp, GSM0808_IE_TMSI) == 4) {
		tmsi = ntohl(tlvp_val32_unal(&tp, GSM0808_IE_TMSI));
		remain -= TLVP_LEN(&tp, GSM0808_IE_TMSI);
	}

	if (remain <= 0) {
		LOGP(DMSC, LOGL_ERROR, "Payload too short.\n");
		return -1;
	}

	/*
	 * parse the IMSI
	 */
	gsm48_mi_to_string(mi_string, sizeof(mi_string),
			   TLVP_VAL(&tp, GSM0808_IE_IMSI), TLVP_LEN(&tp, GSM0808_IE_IMSI));

	/*
	 * There are various cell identifier list types defined at 3GPP TS § 08.08, we don't support all
	 * of them yet. To not disrupt paging operation just because we're lacking some implementation,
	 * interpret any unknown cell identifier type as "page the entire BSS".
	 */
	data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
	data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
	if (gsm0808_dec_cell_id_list2(&cil, data, data_length) < 0) {
		LOGP(DMSC, LOGL_ERROR, "Paging IMSI %s: Could not parse Cell Identifier List\n",
		     mi_string);
		return -1;
	}
	remain = 0;

	if (TLVP_PRESENT(&tp, GSM0808_IE_CHANNEL_NEEDED) && TLVP_LEN(&tp, GSM0808_IE_CHANNEL_NEEDED) == 1)
		chan_needed = TLVP_VAL(&tp, GSM0808_IE_CHANNEL_NEEDED)[0] & 0x03;

	if (TLVP_PRESENT(&tp, GSM0808_IE_EMLPP_PRIORITY)) {
		LOGP(DMSC, LOGL_ERROR, "eMLPP is not handled\n");
	}

	rate_ctr_inc(&msc->network->bsc_ctrs->ctr[BSC_CTR_PAGING_ATTEMPTED]);

	switch (cil.id_discr) {
	case CELL_IDENT_NO_CELL:
		page_all_bts(msc, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_WHOLE_GLOBAL:
		page_cgi(msc, &cil, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_LAC_AND_CI:
		page_lac_and_ci(msc, &cil, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_CI:
		page_ci(msc, &cil, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_LAI_AND_LAC:
		page_lai_and_lac(msc, &cil, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_LAC:
		page_lac(msc, &cil, tmsi, mi_string, chan_needed);
		break;

	case CELL_IDENT_BSS:
		if (data_length != 1) {
			LOGP(DMSC, LOGL_ERROR, "Paging IMSI %s: Cell Identifier List for BSS (0x%x)"
			     " has invalid length: %u, paging entire BSS anyway (%s)\n",
			     mi_string, CELL_IDENT_BSS, data_length, osmo_hexdump(data, data_length));
		}
		page_all_bts(msc, tmsi, mi_string, chan_needed);
		break;

	default:
		LOGP(DMSC, LOGL_NOTICE, "Paging IMSI %s: unimplemented Cell Identifier List (0x%x),"
		     " paging entire BSS instead (%s)\n",
		     mi_string, cil.id_discr, osmo_hexdump(data, data_length));
		page_all_bts(msc, tmsi, mi_string, chan_needed);
		break;
	}

	return 0;
}

/* select the best cipher permitted by the intersection of both masks */
static int select_best_cipher(uint8_t msc_mask, uint8_t bsc_mask)
{
	uint8_t intersection = msc_mask & bsc_mask;
	int i;

	for (i = 7; i >= 0; i--) {
		if (intersection & (1 << i))
			return i;
	}
	return -1;
}

/*
 * GSM 08.08 § 3.4.7 cipher mode handling. We will have to pick
 * the cipher to be used for this. In case we are already using
 * a cipher we will have to send cipher mode reject to the MSC,
 * otherwise we will have to pick something that we and the MS
 * is supporting. Currently we are doing it in a rather static
 * way by picking one encryption or no encryption.
 */
static int bssmap_handle_cipher_mode(struct gsm_subscriber_connection *conn,
				     struct msgb *msg, unsigned int payload_length)
{
	uint16_t len;
	struct gsm_network *network = NULL;
	const uint8_t *data;
	struct tlv_parsed tp;
	struct msgb *resp;
	int reject_cause = -1;
	int include_imeisv = 1;
	const uint8_t *enc_key;
	uint16_t enc_key_len;
	uint8_t enc_bits_msc;
	int chosen_cipher;

	if (!conn) {
		LOGP(DMSC, LOGL_ERROR, "No lchan/msc_data in cipher mode command.\n");
		goto reject;
	}

	if (conn->ciphering_handled) {
		LOGP(DMSC, LOGL_ERROR, "Already seen ciphering command. Protocol Error.\n");
		goto reject;
	}

	conn->ciphering_handled = 1;

	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, payload_length - 1, 0, 0);
	if (!TLVP_PRESENT(&tp, GSM0808_IE_ENCRYPTION_INFORMATION)) {
		LOGP(DMSC, LOGL_ERROR, "IE Encryption Information missing.\n");
		goto reject;
	}

	/*
	 * check if our global setting is allowed
	 *  - Currently we check for A5/0 and A5/1
	 *  - Copy the key if that is necessary
	 *  - Otherwise reject
	 */
	len = TLVP_LEN(&tp, GSM0808_IE_ENCRYPTION_INFORMATION);
	if (len < 1) {
		LOGP(DMSC, LOGL_ERROR, "IE Encryption Information is too short.\n");
		goto reject;
	}

	network = conn_get_bts(conn)->network;
	data = TLVP_VAL(&tp, GSM0808_IE_ENCRYPTION_INFORMATION);
	enc_bits_msc = data[0];
	enc_key = &data[1];
	enc_key_len = len - 1;

	if (TLVP_PRESENT(&tp, GSM0808_IE_CIPHER_RESPONSE_MODE))
		include_imeisv = TLVP_VAL(&tp, GSM0808_IE_CIPHER_RESPONSE_MODE)[0] & 0x1;

	/* Identical to the GSM0808_IE_ENCRYPTION_INFORMATION above:
	 * a5_encryption == 0 --> 0x01
	 * a5_encryption == 1 --> 0x02
	 * a5_encryption == 2 --> 0x04 ... */
	enc_bits_msc = data[0];

	/* The bit-mask of permitted ciphers from the MSC (sent in ASSIGNMENT COMMAND) is intersected
	 * with the vty-configured mask a the BSC.  Finally, the best (highest) possible cipher is
	 * chosen. */
	chosen_cipher = select_best_cipher(enc_bits_msc, network->a5_encryption_mask);
	if (chosen_cipher < 0) {
		LOGP(DMSC, LOGL_ERROR, "Reject: no overlapping A5 ciphers between BSC (0x%02x) "
			"and MSC (0x%02x)\n", network->a5_encryption_mask, enc_bits_msc);
		reject_cause = GSM0808_CAUSE_CIPHERING_ALGORITHM_NOT_SUPPORTED;
		goto reject;
	}

	/* To complete the confusion, gsm0808_cipher_mode again expects the encryption as a number
	 * from 0 to 7. */
	if (gsm0808_cipher_mode(conn, chosen_cipher, enc_key, enc_key_len,
				include_imeisv)) {
		reject_cause = GSM0808_CAUSE_PROTOCOL_ERROR_BETWEEN_BSS_AND_MSC;
		goto reject;
	}
	return 0;

reject:
	resp = gsm0808_create_cipher_reject(reject_cause);
	if (!resp) {
		LOGP(DMSC, LOGL_ERROR, "Sending the cipher reject failed.\n");
		return -1;
	}

	osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_TX_SCCP, resp);
	return -1;
}

/* handle LCLS specific IES in BSSMAP ASS REQ */
static void bssmap_handle_ass_req_lcls(struct gsm_subscriber_connection *conn,
					const struct tlv_parsed *tp)
{
	const struct tlv_p_entry *tlv;
	const uint8_t *config, *control;

	tlv = TLVP_GET(tp, GSM0808_IE_GLOBAL_CALL_REF);
	if (tlv) {
		if (tlv->len > sizeof(conn->lcls.global_call_ref))
			LOGPFSML(conn->fi, LOGL_ERROR, "Global Call Ref IE of %u bytes is too long\n",
				tlv->len);
		else {
			LOGPFSM(conn->fi, "Setting GCR to %s\n", osmo_hexdump_nospc(tlv->val, tlv->len));
			memcpy(&conn->lcls.global_call_ref, tlv->val, tlv->len);
			conn->lcls.global_call_ref_len = tlv->len;
		}
	}

	config = TLVP_VAL_MINLEN(tp, GSM0808_IE_LCLS_CONFIG, 1);
	control = TLVP_VAL_MINLEN(tp, GSM0808_IE_LCLS_CONN_STATUS_CTRL, 1);

	if (config || control) {
		LOGPFSM(conn->fi, "BSSMAP ASS REQ contains LCLS (%s / %s)\n",
			config ? gsm0808_lcls_config_name(*config) : "NULL",
			control ? gsm0808_lcls_control_name(*control) : "NULL");
	}

	/* Update the LCLS state with Config + CSC (if any) */
	lcls_update_config(conn, config, control);

	/* Do not attempt to perform correlation yet, as during processing of the ASS REQ
	 * we don't have the MGCP/MGW connections yet, and hence couldn't enable LS. */
}

/* TS 48.008 3.2.1.91 */
static int bssmap_handle_lcls_connect_ctrl(struct gsm_subscriber_connection *conn,
					   struct msgb *msg, unsigned int length)
{
	struct msgb *resp;
	struct tlv_parsed tp;
	const uint8_t *config, *control;
	int rc;

	OSMO_ASSERT(conn);

	rc = tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, length - 1, 0, 0);
	if (rc < 0) {
		LOGPFSML(conn->fi, LOGL_ERROR, "Error parsing TLVs of LCLS CONNT CTRL: %s\n",
			 msgb_hexdump(msg));
		return rc;
	}
	config = TLVP_VAL_MINLEN(&tp, GSM0808_IE_LCLS_CONFIG, 1);
	control = TLVP_VAL_MINLEN(&tp, GSM0808_IE_LCLS_CONN_STATUS_CTRL, 1);

	LOGPFSM(conn->fi, "Rx LCLS CONNECT CTRL (%s / %s)\n",
		config ? gsm0808_lcls_config_name(*config) : "NULL",
		control ? gsm0808_lcls_control_name(*control) : "NULL");

	if (conn->lcls.global_call_ref_len == 0) {
		LOGPFSML(conn->fi, LOGL_ERROR, "Ignoring LCLS as no GCR was set before\n");
		return 0;
	}
	/* Update the LCLS state with Config + CSC (if any) */
	lcls_update_config(conn, TLVP_VAL_MINLEN(&tp, GSM0808_IE_LCLS_CONFIG, 1),
				TLVP_VAL_MINLEN(&tp, GSM0808_IE_LCLS_CONN_STATUS_CTRL, 1));
	lcls_apply_config(conn);

	LOGPFSM(conn->fi, "Tx LCLS CONNECT CTRL ACK (%s)\n",
		gsm0808_lcls_status_name(lcls_get_status(conn)));
	resp = gsm0808_create_lcls_conn_ctrl_ack(lcls_get_status(conn));
	osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_TX_SCCP, resp);

	return 0;
}


/*
 * Handle the assignment request message.
 *
 * See §3.2.1.1 for the message type
 */
static int bssmap_handle_assignm_req(struct gsm_subscriber_connection *conn,
				     struct msgb *msg, unsigned int length)
{
	struct msgb *resp;
	struct bsc_msc_data *msc;
	struct tlv_parsed tp;
	uint8_t timeslot = 0;
	uint8_t multiplex = 0;
	enum gsm48_chan_mode chan_mode = GSM48_CMODE_SIGN;
	int full_rate = -1;
	bool aoip = false;
	struct sockaddr_storage rtp_addr;
	struct gsm0808_channel_type ct;
	struct gsm0808_speech_codec_list *scl_ptr = NULL;
	uint8_t cause;
	int rc;

	if (!conn) {
		LOGP(DMSC, LOGL_ERROR,
		     "No lchan/msc_data in cipher mode command.\n");
		return -1;
	}

	msc = conn->sccp.msc;

	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, length - 1, 0, 0);

	/* Check for channel type element, if its missing, immediately reject */
	if (!TLVP_PRESENT(&tp, GSM0808_IE_CHANNEL_TYPE)) {
		LOGP(DMSC, LOGL_ERROR, "Mandatory channel type not present.\n");
		cause = GSM0808_CAUSE_INFORMATION_ELEMENT_OR_FIELD_MISSING;
		goto reject;
	}

	/* Decode Channel Type element */
	rc = gsm0808_dec_channel_type(&ct,  TLVP_VAL(&tp, GSM0808_IE_CHANNEL_TYPE),
				      TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE));
	if (rc < 0) {
		LOGP(DMSC, LOGL_ERROR, "unable to decode channel type.\n");
		cause = GSM0808_CAUSE_INCORRECT_VALUE;
		goto reject;
	}

	bssmap_handle_ass_req_lcls(conn, &tp);

	/* Currently we only support a limited subset of all
	 * possible channel types, such as multi-slot or CSD */
	switch (ct.ch_indctr) {
	case GSM0808_CHAN_DATA:
		LOGP(DMSC, LOGL_ERROR, "Unsupported channel type, currently only speech is supported!\n");
		cause = GSM0808_CAUSE_REQ_CODEC_TYPE_OR_CONFIG_NOT_SUPP;
		goto reject;
	case GSM0808_CHAN_SPEECH:
		/* Detect if a CIC code is present, if so, we use the classic ip.access method to
		 * calculate the RTP port */
		if (TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
			conn->user_plane.cic =
				osmo_load16be(TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
			timeslot = conn->user_plane.cic & 0x1f;
			multiplex = (conn->user_plane.cic & ~0x1f) >> 5;
		} else if (TLVP_PRESENT(&tp, GSM0808_IE_AOIP_TRASP_ADDR)) {
			/* Decode AoIP transport address element */
			rc = gsm0808_dec_aoip_trasp_addr(&rtp_addr,
							 TLVP_VAL(&tp, GSM0808_IE_AOIP_TRASP_ADDR),
							 TLVP_LEN(&tp, GSM0808_IE_AOIP_TRASP_ADDR));
			if (rc < 0) {
				LOGP(DMSC, LOGL_ERROR, "Unable to decode AoIP transport address.\n");
				cause = GSM0808_CAUSE_INCORRECT_VALUE;
				goto reject;
			}
			aoip = true;
		} else {
			LOGP(DMSC, LOGL_ERROR, "AoIP transport address and CIC missing. "
			     "Audio would not work; rejecting\n");
			cause = GSM0808_CAUSE_INFORMATION_ELEMENT_OR_FIELD_MISSING;
			goto reject;
		}

		/* Decode speech codec list (AoIP) */
		conn->codec_list_present = false;
		if (aoip) {

			/* Check for speech codec list element */
			if (!TLVP_PRESENT(&tp, GSM0808_IE_SPEECH_CODEC_LIST)) {
				LOGP(DMSC, LOGL_ERROR, "Mandatory speech codec list not present.\n");
				cause = GSM0808_CAUSE_INFORMATION_ELEMENT_OR_FIELD_MISSING;
				goto reject;
			}

			/* Decode Speech Codec list */
			rc = gsm0808_dec_speech_codec_list(&conn->codec_list,
							   TLVP_VAL(&tp, GSM0808_IE_SPEECH_CODEC_LIST),
							   TLVP_LEN(&tp, GSM0808_IE_SPEECH_CODEC_LIST));
			if (rc < 0) {
				LOGP(DMSC, LOGL_ERROR, "Unable to decode speech codec list\n");
				cause = GSM0808_CAUSE_INCORRECT_VALUE;
				goto reject;
			}
			conn->codec_list_present = true;
			scl_ptr = &conn->codec_list;
		}

		/* Match codec information from the assignment command against the
		 * local preferences of the BSC */
		rc = match_codec_pref(&full_rate, &chan_mode, &ct, scl_ptr, msc);
		if (rc < 0) {
			LOGP(DMSC, LOGL_ERROR, "No supported audio type found for channel_type ="
			     " { ch_indctr=0x%x, ch_rate_type=0x%x, perm_spch=[ %s] }\n",
			     ct.ch_indctr, ct.ch_rate_type, osmo_hexdump(ct.perm_spch, ct.perm_spch_len));
			/* TODO: actually output codec names, e.g. implement
			 * gsm0808_permitted_speech_names[] and iterate perm_spch. */
			cause = GSM0808_CAUSE_REQ_CODEC_TYPE_OR_CONFIG_UNAVAIL;
			goto reject;
		}

		DEBUGP(DMSC, "Found matching audio type: %s %s for channel_type ="
		       " { ch_indctr=0x%x, ch_rate_type=0x%x, perm_spch=[ %s] }\n",
		       full_rate? "full rate" : "half rate",
		       get_value_string(gsm48_chan_mode_names, chan_mode),
		       ct.ch_indctr, ct.ch_rate_type, osmo_hexdump(ct.perm_spch, ct.perm_spch_len));

		/* Forward the assignment request to lower layers */
		if (aoip) {
			/* Store network side RTP connection information, we will
			 * process this address later after we have established an RTP
			 * connection to the BTS. This is just for organizational
			 * reasons, functional wise it would not matter when exactly
			 * the network side RTP connection is made, as long it is made
			 * before we return with the assignment complete message. */
			memcpy(&conn->user_plane.aoip_rtp_addr_remote, &rtp_addr, sizeof(rtp_addr));
		} else {
			/* Note: In the sccp-lite case we to not perform any mgcp operation,
			 * (the MSC does that for us). We set conn->rtp_ip to 0 and check
			 * on this later. By this we know that we have to behave accordingly
			 * to sccp-lite. */
			conn->user_plane.rtp_port = mgcp_timeslot_to_port(multiplex, timeslot, msc->rtp_base);
			conn->user_plane.rtp_ip = 0;
		}
		conn->user_plane.chan_mode = chan_mode;
		conn->user_plane.full_rate = full_rate;
		osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_A_ASSIGNMENT_CMD, NULL);
		break;
	case GSM0808_CHAN_SIGN:
		conn->user_plane.chan_mode = GSM48_CMODE_SIGN;
		osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_A_ASSIGNMENT_CMD, NULL);
		break;
	default:
		cause = GSM0808_CAUSE_INVALID_MESSAGE_CONTENTS;
		goto reject;
	}

	return 0;
reject:
	resp = gsm0808_create_assignment_failure(cause, NULL);
	OSMO_ASSERT(resp);

	osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_TX_SCCP, resp);
	return -1;
}

static int bssmap_rcvmsg_udt(struct bsc_msc_data *msc,
			     struct msgb *msg, unsigned int length)
{
	int ret = 0;

	if (length < 1) {
		LOGP(DMSC, LOGL_ERROR, "Not enough room: %d\n", length);
		return -1;
	}

	LOGP(DMSC, LOGL_INFO, "Rx MSC UDT BSSMAP %s\n",
		gsm0808_bssmap_name(msg->l4h[0]));

	switch (msg->l4h[0]) {
	case BSS_MAP_MSG_RESET_ACKNOWLEDGE:
		ret = bssmap_handle_reset_ack(msc, msg, length);
		break;
	case BSS_MAP_MSG_RESET:
		ret = bssmap_handle_reset(msc, msg, length);
		break;
	case BSS_MAP_MSG_PAGING:
		ret = bssmap_handle_paging(msc, msg, length);
		break;
	default:
		LOGP(DMSC, LOGL_NOTICE, "Received unimplemented BSSMAP UDT %s\n",
			gsm0808_bssmap_name(msg->l4h[0]));
		break;
	}

	return ret;
}

static int bssmap_rcvmsg_dt1(struct gsm_subscriber_connection *conn,
			     struct msgb *msg, unsigned int length)
{
	int ret = 0;

	if (length < 1) {
		LOGP(DMSC, LOGL_ERROR, "Not enough room: %d\n", length);
		return -1;
	}

	LOGP(DMSC, LOGL_INFO, "Rx MSC DT1 BSSMAP %s\n",
		gsm0808_bssmap_name(msg->l4h[0]));

	switch (msg->l4h[0]) {
	case BSS_MAP_MSG_CLEAR_CMD:
		osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_A_CLEAR_CMD, msg);
		break;
	case BSS_MAP_MSG_CIPHER_MODE_CMD:
		ret = bssmap_handle_cipher_mode(conn, msg, length);
		break;
	case BSS_MAP_MSG_ASSIGMENT_RQST:
		ret = bssmap_handle_assignm_req(conn, msg, length);
		break;
	case BSS_MAP_MSG_LCLS_CONNECT_CTRL:
		ret = bssmap_handle_lcls_connect_ctrl(conn, msg, length);
		break;
	default:
		LOGP(DMSC, LOGL_NOTICE, "Unimplemented msg type: %s\n",
			gsm0808_bssmap_name(msg->l4h[0]));
		break;
	}

	return ret;
}

static int dtap_rcvmsg(struct gsm_subscriber_connection *conn,
		       struct msgb *msg, unsigned int length)
{
	struct dtap_header *header;
	struct msgb *gsm48;
	uint8_t *data;
	int rc, dtap_rc;

	LOGP(DMSC, LOGL_DEBUG, "Rx MSC DTAP: %s\n",
		osmo_hexdump(msg->l3h, length));

	if (!conn) {
		LOGP(DMSC, LOGL_ERROR, "No subscriber connection available\n");
		return -1;
	}

	header = (struct dtap_header *) msg->l3h;
	if (sizeof(*header) >= length) {
		LOGP(DMSC, LOGL_ERROR, "The DTAP header does not fit. Wanted: %zu got: %u\n", sizeof(*header), length);
                LOGP(DMSC, LOGL_ERROR, "hex: %s\n", osmo_hexdump(msg->l3h, length));
                return -1;
	}

	if (header->length > length - sizeof(*header)) {
		LOGP(DMSC, LOGL_ERROR, "The DTAP l4 information does not fit: header: %u length: %u\n", header->length, length);
                LOGP(DMSC, LOGL_ERROR, "hex: %s\n", osmo_hexdump(msg->l3h, length));
		return -1;
	}

	LOGP(DMSC, LOGL_INFO, "Rx MSC DTAP, SAPI: %u CHAN: %u\n", header->link_id & 0x07, header->link_id & 0xC0);

	/* forward the data */
	gsm48 = gsm48_msgb_alloc_name("GSM 04.08 DTAP RCV");
	if (!gsm48) {
		LOGP(DMSC, LOGL_ERROR, "Allocation of the message failed.\n");
		return -1;
	}

	gsm48->l3h = gsm48->data;
	data = msgb_put(gsm48, length - sizeof(*header));
	memcpy(data, msg->l3h + sizeof(*header), length - sizeof(*header));

	/* pass it to the filter for extra actions */
	rc = bsc_scan_msc_msg(conn, gsm48);
	/* Store link_id in msgb->cb */
	OBSC_LINKID_CB(msg) = header->link_id;
	dtap_rc = osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_MT_DTAP, gsm48);
	if (rc == BSS_SEND_USSD)
		bsc_send_welcome_ussd(conn);
	return dtap_rc;
}

int bsc_handle_udt(struct bsc_msc_data *msc,
		   struct msgb *msgb, unsigned int length)
{
	struct bssmap_header *bs;

	LOGP(DMSC, LOGL_DEBUG, "Rx MSC UDT: %s\n",
		osmo_hexdump(msgb->l3h, length));

	if (length < sizeof(*bs)) {
		LOGP(DMSC, LOGL_ERROR, "The header is too short.\n");
		return -1;
	}

	bs = (struct bssmap_header *) msgb->l3h;
	if (bs->length < length - sizeof(*bs))
		return -1;

	switch (bs->type) {
	case BSSAP_MSG_BSS_MANAGEMENT:
		msgb->l4h = &msgb->l3h[sizeof(*bs)];
		bssmap_rcvmsg_udt(msc, msgb, length - sizeof(*bs));
		break;
	default:
		LOGP(DMSC, LOGL_NOTICE, "Unimplemented msg type: %s\n",
			gsm0808_bssmap_name(bs->type));
	}

	return 0;
}

int bsc_handle_dt(struct gsm_subscriber_connection *conn,
		  struct msgb *msg, unsigned int len)
{
	if (len < sizeof(struct bssmap_header)) {
		LOGP(DMSC, LOGL_ERROR, "The header is too short.\n");
	}

	switch (msg->l3h[0]) {
	case BSSAP_MSG_BSS_MANAGEMENT:
		msg->l4h = &msg->l3h[sizeof(struct bssmap_header)];
		bssmap_rcvmsg_dt1(conn, msg, len - sizeof(struct bssmap_header));
		break;
	case BSSAP_MSG_DTAP:
		dtap_rcvmsg(conn, msg, len);
		break;
	default:
		LOGP(DMSC, LOGL_NOTICE, "Unimplemented BSSAP msg type: %s\n",
			gsm0808_bssap_name(msg->l3h[0]));
	}

	return -1;
}