aboutsummaryrefslogtreecommitdiffstats
path: root/openbsc/src/libbsc/bsc_api.c
blob: cc12e9f7e9c748b4bc36f4876df5c390d596472e (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
/* GSM 08.08 like API for OpenBSC. The bridge from MSC to BSC */

/* (C) 2010-2011 by Holger Hans Peter Freyther
 * (C) 2010-2011 by On-Waves
 * (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 <openbsc/bsc_api.h>
#include <openbsc/bsc_rll.h>
#include <openbsc/gsm_data.h>
#include <openbsc/gsm_subscriber.h>
#include <openbsc/signal.h>
#include <openbsc/abis_rsl.h>
#include <openbsc/chan_alloc.h>
#include <openbsc/handover.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_04_08.h>
#include <openbsc/trau_mux.h>

#include <osmocom/gsm/protocol/gsm_08_08.h>

#include <osmocom/core/talloc.h>

#define GSM0808_T10_VALUE    6, 0


static void rll_ind_cb(struct gsm_lchan *, uint8_t, void *, enum bsc_rllr_ind);
static void send_sapi_reject(struct gsm_subscriber_connection *conn, int link_id);
static void handle_release(struct gsm_subscriber_connection *conn, struct bsc_api *bsc, struct  gsm_lchan *lchan);
static void handle_chan_ack(struct gsm_subscriber_connection *conn, struct bsc_api *bsc, struct  gsm_lchan *lchan);
static void handle_chan_nack(struct gsm_subscriber_connection *conn, struct bsc_api *bsc, struct  gsm_lchan *lchan);

/* GSM 08.08 3.2.2.33 */
static uint8_t lchan_to_chosen_channel(struct gsm_lchan *lchan)
{
	uint8_t channel_mode = 0, channel = 0;

	switch (lchan->tch_mode) {
	case GSM48_CMODE_SPEECH_V1:
	case GSM48_CMODE_SPEECH_EFR:
	case GSM48_CMODE_SPEECH_AMR:
		channel_mode = 0x9;
		break;
	case GSM48_CMODE_SIGN:
		channel_mode = 0x8;
		break;
	case GSM48_CMODE_DATA_14k5:
		channel_mode = 0xe;
		break;
	case GSM48_CMODE_DATA_12k0:
		channel_mode = 0xb;
		break;
	case GSM48_CMODE_DATA_6k0:
		channel_mode = 0xc;
		break;
	case GSM48_CMODE_DATA_3k6:
		channel_mode = 0xd;
		break;
	}

	switch (lchan->type) {
	case GSM_LCHAN_NONE:
		channel = 0x0;
		break;
	case GSM_LCHAN_SDCCH:
		channel = 0x1;
		break;
	case GSM_LCHAN_TCH_F:
		channel = 0x8;
		break;
	case GSM_LCHAN_TCH_H:
		channel = 0x9;
		break;
	case GSM_LCHAN_UNKNOWN:
	default:
		LOGP(DMSC, LOGL_ERROR, "Unknown lchan type: %p\n", lchan);
		break;
	}

	return channel_mode << 4 | channel;
}

static uint8_t chan_mode_to_speech(struct gsm_lchan *lchan)
{
	int mode = 0;

	switch (lchan->tch_mode) {
	case GSM48_CMODE_SPEECH_V1:
		mode = 1;
		break;
	case GSM48_CMODE_SPEECH_EFR:
		mode = 0x11;
		break;
	case GSM48_CMODE_SPEECH_AMR:
		mode = 0x21;
		break;
	case GSM48_CMODE_SIGN:
	case GSM48_CMODE_DATA_14k5:
	case GSM48_CMODE_DATA_12k0:
	case GSM48_CMODE_DATA_6k0:
	case GSM48_CMODE_DATA_3k6:
	default:
		LOGP(DMSC, LOGL_ERROR, "Using non speech mode: %d\n", mode);
		return 0;
		break;
	}

	/* assume to always do AMR HR on any TCH type */
	if (lchan->type == GSM_LCHAN_TCH_H ||
	    lchan->tch_mode == GSM48_CMODE_SPEECH_AMR)
		mode |= 0x4;

        return mode;
}

static void assignment_t10_timeout(void *_conn)
{
	struct bsc_api *api;
	struct gsm_subscriber_connection *conn =
		(struct gsm_subscriber_connection *) _conn;

	LOGP(DMSC, LOGL_ERROR, "Assigment T10 timeout on %p\n", conn);

	/*
	 * normal release on the secondary channel but only if the
	 * secondary_channel has not been released by the handle_chan_nack.
	 */
	if (conn->secondary_lchan)
		lchan_release(conn->secondary_lchan, 0, RSL_REL_LOCAL_END);
	conn->secondary_lchan = NULL;

	/* inform them about the failure */
	api = conn->network->bsc_api;
	api->assign_fail(conn, GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE, NULL);
}

/**
 * Handle the multirate config
 */
static void handle_mr_config(struct gsm_subscriber_connection *conn,
			     struct gsm_lchan *lchan, int full_rate)
{
	struct bsc_api *api;
	api = conn->network->bsc_api;
	struct amr_multirate_conf *mr;
	struct gsm48_multi_rate_conf *mr_conf;

	if (api->mr_config)
		return api->mr_config(conn, lchan, full_rate);

	if (full_rate)
		mr = &lchan->ts->trx->bts->mr_full;
	else
		mr = &lchan->ts->trx->bts->mr_half;

	mr_conf = (struct gsm48_multi_rate_conf *) mr->gsm48_ie;
	mr_conf->ver = 1;

	/* default, if no AMR codec defined */
	if (!mr->gsm48_ie[1]) {
		mr_conf->icmi = 1;
		mr_conf->m5_90 = 1;
	}
	gsm48_multirate_config(lchan->mr_ms_lv, mr, mr->ms_mode);
	gsm48_multirate_config(lchan->mr_bts_lv, mr, mr->bts_mode);
}

/*
 * Start a new assignment and make sure that it is completed within T10 either
 * positively, negatively or by the timeout.
 *
 *  1.) allocate a new lchan
 *  2.) copy the encryption key and other data from the
 *      old to the new channel.
 *  3.) RSL Channel Activate this channel and wait
 *
 * -> Signal handler for the LCHAN
 *  4.) Send GSM 04.08 assignment command to the MS
 *
 * -> Assignment Complete/Assignment Failure
 *  5.) Release the SDCCH, continue signalling on the new link
 */
static int handle_new_assignment(struct gsm_subscriber_connection *conn, int chan_mode, int full_rate)
{
	struct gsm_lchan *new_lchan;
	int chan_type;

	chan_type = full_rate ? GSM_LCHAN_TCH_F : GSM_LCHAN_TCH_H;

	new_lchan = lchan_alloc(conn->bts, chan_type, 0);

	if (!new_lchan) {
		LOGP(DMSC, LOGL_NOTICE, "No free channel.\n");
		return -1;
	}

	/* copy old data to the new channel */
	memcpy(&new_lchan->encr, &conn->lchan->encr, sizeof(new_lchan->encr));
	new_lchan->ms_power = conn->lchan->ms_power;
	new_lchan->bs_power = conn->lchan->bs_power;
	new_lchan->rqd_ta = conn->lchan->rqd_ta;

	/* copy new data to it */
	new_lchan->tch_mode = chan_mode;
	new_lchan->rsl_cmode = RSL_CMOD_SPD_SPEECH;

	/* handle AMR correctly */
	if (chan_mode == GSM48_CMODE_SPEECH_AMR)
		handle_mr_config(conn, new_lchan, full_rate);

	if (rsl_chan_activate_lchan(new_lchan, 0x1, 0) < 0) {
		LOGP(DHO, LOGL_ERROR, "could not activate channel\n");
		lchan_free(new_lchan);
		return -1;
	}

	/* remember that we have the channel */
	conn->secondary_lchan = new_lchan;
	new_lchan->conn = conn;

	rsl_lchan_set_state(new_lchan, LCHAN_S_ACT_REQ);
	return 0;
}

struct gsm_subscriber_connection *subscr_con_allocate(struct gsm_lchan *lchan)
{
	struct gsm_subscriber_connection *conn;
	struct gsm_network *net = lchan->ts->trx->bts->network;

	conn = talloc_zero(net, struct gsm_subscriber_connection);
	if (!conn)
		return NULL;

	conn->network = net;
	conn->lchan = lchan;
	conn->bts = lchan->ts->trx->bts;
	lchan->conn = conn;
	llist_add_tail(&conn->entry, &net->subscr_conns);
	return conn;
}

/* TODO: move subscriber put here... */
void subscr_con_free(struct gsm_subscriber_connection *conn)
{
	if (!conn)
		return;


	if (conn->subscr) {
		subscr_put(conn->subscr);
		conn->subscr = NULL;
	}


	if (conn->ho_lchan) {
		LOGP(DNM, LOGL_ERROR, "The ho_lchan should have been cleared.\n");
		conn->ho_lchan->conn = NULL;
	}

	if (conn->lchan) {
		LOGP(DNM, LOGL_ERROR, "The lchan should have been cleared.\n");
		conn->lchan->conn = NULL;
	}

	if (conn->secondary_lchan) {
		LOGP(DNM, LOGL_ERROR, "The secondary_lchan should have been cleared.\n");
		conn->secondary_lchan->conn = NULL;
	}

	llist_del(&conn->entry);
	talloc_free(conn);
}

int bsc_api_init(struct gsm_network *network, struct bsc_api *api)
{
	network->bsc_api = api;
	return 0;
}

/*! \brief process incoming 08.08 DTAP from MSC (send via BTS to MS) */
int gsm0808_submit_dtap(struct gsm_subscriber_connection *conn,
			struct msgb *msg, int link_id, int allow_sacch)
{
	uint8_t sapi;


	if (!conn->lchan) {
		LOGP(DMSC, LOGL_ERROR,
		     "Called submit dtap without an lchan.\n");
		msgb_free(msg);
		return -1;
	}

	sapi = link_id & 0x7;
	msg->lchan = conn->lchan;
	msg->dst = msg->lchan->ts->trx->rsl_link;

	/* If we are on a TCH and need to submit a SMS (on SAPI=3) we need to use the SACH */
	if (allow_sacch && sapi != 0) {
		if (conn->lchan->type == GSM_LCHAN_TCH_F || conn->lchan->type == GSM_LCHAN_TCH_H)
			link_id |= 0x40;
	}

	msg->l3h = msg->data;
	/* is requested SAPI already up? */
	if (conn->lchan->sapis[sapi] == LCHAN_SAPI_UNUSED) {
		/* Establish L2 for additional SAPI */
		OBSC_LINKID_CB(msg) = link_id;
		if (rll_establish(msg->lchan, sapi, rll_ind_cb, msg) != 0) {
			msgb_free(msg);
			send_sapi_reject(conn, link_id);
			return -1;
		}
		return 0;
	} else {
		/* Directly forward via RLL/RSL to BTS */
		return rsl_data_request(msg, link_id);
	}
}

/*
 * \brief Check if the given channel is compatible with the mode/fullrate
 */
static int chan_compat_with_mode(struct gsm_lchan *lchan, int chan_mode, int full_rate)
{
	switch (chan_mode) {
	case GSM48_CMODE_SIGN:
		/* signalling is always possible */
		return 1;
	case GSM48_CMODE_SPEECH_V1:
	case GSM48_CMODE_SPEECH_AMR:
	case GSM48_CMODE_DATA_3k6:
	case GSM48_CMODE_DATA_6k0:
		/* these services can all run on TCH/H, but we may have
		 * an explicit override by the 'full_rate' argument */
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return 1;
		case GSM_LCHAN_TCH_H:
			if (full_rate)
				return 0;
			else
				return 1;
			break;
		default:
			return 0;
		}
		break;
	case GSM48_CMODE_DATA_12k0:
	case GSM48_CMODE_DATA_14k5:
	case GSM48_CMODE_SPEECH_EFR:
		/* these services all explicitly require a TCH/F */
		if (lchan->type == GSM_LCHAN_TCH_F)
			return 1;
		else
			return 0;
		break;
	}

	return 0;
}

/**
 * Send a GSM08.08 Assignment Request. Right now this does not contain the
 * audio codec type or the allowed rates for the config. It is assumed that
 * this is for audio handling only. In case the current channel does not allow
 * the selected mode a new one will be allocated.
 *
 * TODO: Add multirate configuration, make it work for more than audio.
 */
int gsm0808_assign_req(struct gsm_subscriber_connection *conn, int chan_mode, int full_rate)
{
	struct bsc_api *api;
	api = conn->network->bsc_api;

	if (!chan_compat_with_mode(conn->lchan, chan_mode, full_rate)) {
		if (handle_new_assignment(conn, chan_mode, full_rate) != 0)
			goto error;
	} else {
		if (chan_mode == GSM48_CMODE_SPEECH_AMR)
			handle_mr_config(conn, conn->lchan, full_rate);

		LOGP(DMSC, LOGL_NOTICE,
		     "Sending ChanModify for speech: %s on channel %s\n",
		     get_value_string(gsm48_chan_mode_names, chan_mode),
		     get_value_string(gsm_chan_t_names, conn->lchan->type));
		gsm48_lchan_modify(conn->lchan, chan_mode);
	}

	/* we will now start the timer to complete the assignment */
	conn->T10.cb = assignment_t10_timeout;
	conn->T10.data = conn;
	osmo_timer_schedule(&conn->T10, GSM0808_T10_VALUE);
	return 0;

error:
	api->assign_fail(conn, 0, NULL);
	return -1;
}

int gsm0808_page(struct gsm_bts *bts, unsigned int page_group, unsigned int mi_len,
		 uint8_t *mi, int chan_type)
{
	return rsl_paging_cmd(bts, page_group, mi_len, mi, chan_type);
}

static void handle_ass_compl(struct gsm_subscriber_connection *conn,
			     struct msgb *msg)
{
	struct gsm48_hdr *gh;
	struct bsc_api *api = conn->network->bsc_api;

	if (conn->secondary_lchan != msg->lchan) {
		LOGP(DMSC, LOGL_ERROR, "Assignment Compl should occur on second lchan.\n");
		return;
	}

	gh = msgb_l3(msg);
	if (msgb_l3len(msg) - sizeof(*gh) != 1) {
		LOGP(DMSC, LOGL_ERROR, "Assignment Compl invalid: %zu\n",
		     msgb_l3len(msg) - sizeof(*gh));
		return;
	}

	/* switch TRAU muxer for E1 based BTS from one channel to another */
	if (is_e1_bts(conn->bts))
		switch_trau_mux(conn->lchan, conn->secondary_lchan);

	/* swap channels */
	osmo_timer_del(&conn->T10);

	lchan_release(conn->lchan, 0, RSL_REL_LOCAL_END);
	conn->lchan = conn->secondary_lchan;
	conn->secondary_lchan = NULL;

	if (is_ipaccess_bts(conn->bts) && conn->lchan->tch_mode != GSM48_CMODE_SIGN)
		rsl_ipacc_crcx(conn->lchan);

	api->assign_compl(conn, gh->data[0],
			  lchan_to_chosen_channel(conn->lchan),
			  conn->lchan->encr.alg_id,
			  chan_mode_to_speech(conn->lchan));
}

static void handle_ass_fail(struct gsm_subscriber_connection *conn,
			    struct msgb *msg)
{
	struct bsc_api *api = conn->network->bsc_api;
	uint8_t *rr_failure;
	struct gsm48_hdr *gh;


	if (conn->lchan != msg->lchan) {
		LOGP(DMSC, LOGL_ERROR, "Assignment failure should occur on primary lchan.\n");
		return;
	}

	/* stop the timer and release it */
	osmo_timer_del(&conn->T10);
	lchan_release(conn->secondary_lchan, 0, RSL_REL_LOCAL_END);
	conn->secondary_lchan = NULL;

	gh = msgb_l3(msg);
	if (msgb_l3len(msg) - sizeof(*gh) != 1) {
		LOGP(DMSC, LOGL_ERROR, "assignemnt failure unhandled: %zu\n",
		     msgb_l3len(msg) - sizeof(*gh));
		rr_failure = NULL;
	} else {
		rr_failure = &gh->data[0];
	}

	api->assign_fail(conn,
			 GSM0808_CAUSE_RADIO_INTERFACE_MESSAGE_FAILURE,
			 rr_failure);
}

static void handle_classmark_chg(struct gsm_subscriber_connection *conn,
				 struct msgb *msg)
{
	struct bsc_api *api = msg->lchan->ts->trx->bts->network->bsc_api;
	struct gsm48_hdr *gh = msgb_l3(msg);
	unsigned int payload_len = msgb_l3len(msg) - sizeof(*gh);
	uint8_t cm2_len, cm3_len = 0;
	uint8_t *cm2, *cm3 = NULL;

	DEBUGP(DRR, "CLASSMARK CHANGE ");

	/* classmark 2 */
	cm2_len = gh->data[0];
	cm2 = &gh->data[1];
	DEBUGPC(DRR, "CM2(len=%u) ", cm2_len);

	if (payload_len > cm2_len + 1) {
		/* we must have a classmark3 */
		if (gh->data[cm2_len+1] != 0x20) {
			DEBUGPC(DRR, "ERR CM3 TAG\n");
			return;
		}
		if (cm2_len > 3) {
			DEBUGPC(DRR, "CM2 too long!\n");
			return;
		}

		cm3_len = gh->data[cm2_len+2];
		cm3 = &gh->data[cm2_len+3];
		if (cm3_len > 14) {
			DEBUGPC(DRR, "CM3 len %u too long!\n", cm3_len);
			return;
		}
		DEBUGPC(DRR, "CM3(len=%u)\n", cm3_len);
	}
	api->classmark_chg(conn, cm2, cm2_len, cm3, cm3_len);
}

/* Chapter 9.1.16 Handover complete */
static void handle_rr_ho_compl(struct msgb *msg)
{
	struct lchan_signal_data sig;
	struct gsm48_hdr *gh = msgb_l3(msg);

	DEBUGP(DRR, "HANDOVER COMPLETE cause = %s\n",
		rr_cause_name(gh->data[0]));

	sig.lchan = msg->lchan;
	sig.mr = NULL;
	osmo_signal_dispatch(SS_LCHAN, S_LCHAN_HANDOVER_COMPL, &sig);
	/* FIXME: release old channel */
}

/* Chapter 9.1.17 Handover Failure */
static void handle_rr_ho_fail(struct msgb *msg)
{
	struct lchan_signal_data sig;
	struct gsm48_hdr *gh = msgb_l3(msg);

	DEBUGP(DRR, "HANDOVER FAILED cause = %s\n",
		rr_cause_name(gh->data[0]));

	sig.lchan = msg->lchan;
	sig.mr = NULL;
	osmo_signal_dispatch(SS_LCHAN, S_LCHAN_HANDOVER_FAIL, &sig);
	/* FIXME: release allocated new channel */
}


static void dispatch_dtap(struct gsm_subscriber_connection *conn,
			  uint8_t link_id, struct msgb *msg)
{
	struct bsc_api *api = msg->lchan->ts->trx->bts->network->bsc_api;
	struct gsm48_hdr *gh;
	uint8_t pdisc;
	uint8_t msg_type;
	int rc;

	if (msgb_l3len(msg) < sizeof(*gh)) {
		LOGP(DMSC, LOGL_ERROR, "Message too short for a GSM48 header.\n");
		return;
	}

	gh = msgb_l3(msg);
	pdisc = gsm48_hdr_pdisc(gh);
	msg_type = gsm48_hdr_msg_type(gh);

	/* the idea is to handle all RR messages here, and only hand
	 * MM/CC/SMS-CP/LCS up to the MSC.  Some messages like PAGING
	 * RESPONSE or CM SERVICE REQUEST will not be covered here, as
	 * they are only possible in the first L3 message of each L2
	 * channel, i.e. 'conn' will not exist and gsm0408_rcvmsg()
	 * will call api->compl_l3() for it */
	switch (pdisc) {
	case GSM48_PDISC_RR:
		switch (msg_type) {
		case GSM48_MT_RR_GPRS_SUSP_REQ:
			DEBUGP(DRR, "GRPS SUSPEND REQUEST\n");
			break;
		case GSM48_MT_RR_STATUS:
			LOGP(DRR, LOGL_NOTICE, "RR STATUS (cause: %s)\n",
				rr_cause_name(gh->data[0]));
			break;
		case GSM48_MT_RR_MEAS_REP:
			/* This shouldn't actually end up here, as RSL treats
			* L3 Info of 08.58 MEASUREMENT REPORT different by calling
			* directly into gsm48_parse_meas_rep */
			LOGP(DMEAS, LOGL_ERROR, "DIRECT GSM48 MEASUREMENT REPORT ?!? ");
			break;
		case GSM48_MT_RR_HANDO_COMPL:
			handle_rr_ho_compl(msg);
			break;
		case GSM48_MT_RR_HANDO_FAIL:
			handle_rr_ho_fail(msg);
			break;
		case GSM48_MT_RR_CIPH_M_COMPL:
			if (api->cipher_mode_compl)
				api->cipher_mode_compl(conn, msg,
						conn->lchan->encr.alg_id);
			break;
		case GSM48_MT_RR_ASS_COMPL:
			handle_ass_compl(conn, msg);
			break;
		case GSM48_MT_RR_ASS_FAIL:
			handle_ass_fail(conn, msg);
			break;
		case GSM48_MT_RR_CHAN_MODE_MODIF_ACK:
			osmo_timer_del(&conn->T10);
			rc = gsm48_rx_rr_modif_ack(msg);
			if (rc < 0) {
				api->assign_fail(conn,
						 GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE,
						 NULL);
			} else if (rc >= 0) {
				api->assign_compl(conn, 0,
						  lchan_to_chosen_channel(conn->lchan),
						  conn->lchan->encr.alg_id,
						  chan_mode_to_speech(conn->lchan));
			}
			break;
		case GSM48_MT_RR_CLSM_CHG:
			handle_classmark_chg(conn, msg);
			break;
		case GSM48_MT_RR_APP_INFO:
			/* Passing RR APP INFO to MSC, not quite
			 * according to spec */
			if (api->dtap)
				api->dtap(conn, link_id, msg);
			break;
		default:
			/* Normally, a MSC should never receive RR
			 * messages, but we'd rather forward what we
			 * don't know than drop it... */
			LOGP(DRR, LOGL_NOTICE, "BSC: Passing unknown 04.08 "
			     "RR message type 0x%02x to MSC\n", msg_type);
			if (api->dtap)
				api->dtap(conn, link_id, msg);
		}
		break;
	default:
		if (api->dtap)
			api->dtap(conn, link_id, msg);
		break;
	}
}

/*! \brief RSL has received a DATA INDICATION with L3 from MS */
int gsm0408_rcvmsg(struct msgb *msg, uint8_t link_id)
{
	int rc;
	struct bsc_api *api = msg->lchan->ts->trx->bts->network->bsc_api;
	struct gsm_lchan *lchan;

	lchan = msg->lchan;
	if (lchan->state != LCHAN_S_ACTIVE) {
		LOGP(DRSL, LOGL_INFO, "Got data in non active state(%s), "
		     "discarding.\n", gsm_lchans_name(lchan->state));
		return -1;
	}


	if (lchan->conn) {
		/* if we already have a connection, forward via DTAP to
		 * MSC */
		dispatch_dtap(lchan->conn, link_id, msg);
	} else {
		/* allocate a new connection */
		rc = BSC_API_CONN_POL_REJECT;
		lchan->conn = subscr_con_allocate(msg->lchan);
		if (!lchan->conn) {
			lchan_release(lchan, 1, RSL_REL_NORMAL);
			return -1;
		}

		/* fwd via bsc_api to send COMPLETE L3 INFO to MSC */
		rc = api->compl_l3(lchan->conn, msg, 0);

		if (rc != BSC_API_CONN_POL_ACCEPT) {
			lchan->conn->lchan = NULL;
			subscr_con_free(lchan->conn);
			lchan_release(lchan, 1, RSL_REL_NORMAL);
		}
	}

	return 0;
}

/*! \brief We received a GSM 08.08 CIPHER MODE from the MSC */
int gsm0808_cipher_mode(struct gsm_subscriber_connection *conn, int cipher,
			const uint8_t *key, int len, int include_imeisv)
{
	if (cipher > 0 && key == NULL) {
		LOGP(DRSL, LOGL_ERROR, "Need to have an encrytpion key.\n");
		return -1;
	}

	if (len > MAX_A5_KEY_LEN) {
		LOGP(DRSL, LOGL_ERROR, "The key is too long: %d\n", len);
		return -1;
	}

	conn->lchan->encr.alg_id = RSL_ENC_ALG_A5(cipher);
	if (key) {
		conn->lchan->encr.key_len = len;
		memcpy(conn->lchan->encr.key, key, len);
	}

	return gsm48_send_rr_ciph_mode(conn->lchan, include_imeisv);
}

/*
 * Release all occupied RF Channels but stay around for more.
 */
int gsm0808_clear(struct gsm_subscriber_connection *conn)
{
	if (conn->ho_lchan)
		bsc_clear_handover(conn, 1);

	if (conn->secondary_lchan)
		lchan_release(conn->secondary_lchan, 0, RSL_REL_LOCAL_END);

	if (conn->lchan)
		lchan_release(conn->lchan, 1, RSL_REL_NORMAL);

	conn->lchan = NULL;
	conn->secondary_lchan = NULL;
	conn->ho_lchan = NULL;
	conn->bts = NULL;

	osmo_timer_del(&conn->T10);

	return 0;
}

static void send_sapi_reject(struct gsm_subscriber_connection *conn, int link_id)
{
	struct bsc_api *api;

	if (!conn)
		return;

	api = conn->network->bsc_api;
	if (!api || !api->sapi_n_reject)
		return;

	api->sapi_n_reject(conn, link_id);
}

static void rll_ind_cb(struct gsm_lchan *lchan, uint8_t link_id, void *_data, enum bsc_rllr_ind rllr_ind)
{
	struct msgb *msg = _data;

	/*
	 * There seems to be a small window that the RLL timer can
	 * fire after a lchan_release call and before the S_CHALLOC_FREED
	 * is called. Check if a conn is set before proceeding.
	 */
	if (!lchan->conn)
		return;

	switch (rllr_ind) {
	case BSC_RLLR_IND_EST_CONF:
		rsl_data_request(msg, OBSC_LINKID_CB(msg));
		break;
	case BSC_RLLR_IND_REL_IND:
	case BSC_RLLR_IND_ERR_IND:
	case BSC_RLLR_IND_TIMEOUT:
		send_sapi_reject(lchan->conn, OBSC_LINKID_CB(msg));
		msgb_free(msg);
		break;
	}
}

static int bsc_handle_lchan_signal(unsigned int subsys, unsigned int signal,
				   void *handler_data, void *signal_data)
{
	struct bsc_api *bsc;
	struct gsm_lchan *lchan;
	struct lchan_signal_data *lchan_data;

	if (subsys != SS_LCHAN)
		return 0;


	lchan_data = signal_data;
	if (!lchan_data->lchan || !lchan_data->lchan->conn)
		return 0;

	lchan = lchan_data->lchan;
	bsc = lchan->ts->trx->bts->network->bsc_api;
	if (!bsc)
		return 0;

	switch (signal) {
	case S_LCHAN_UNEXPECTED_RELEASE:
		handle_release(lchan->conn, bsc, lchan);
		break;
	case S_LCHAN_ACTIVATE_ACK:
		handle_chan_ack(lchan->conn, bsc, lchan);
		break;
	case S_LCHAN_ACTIVATE_NACK:
		handle_chan_nack(lchan->conn, bsc, lchan);
		break;
	}

	return 0;
}

static void handle_release(struct gsm_subscriber_connection *conn,
			   struct bsc_api *bsc, struct gsm_lchan *lchan)
{
	int destruct = 1;

	if (conn->secondary_lchan == lchan) {
		osmo_timer_del(&conn->T10);
		conn->secondary_lchan = NULL;

		bsc->assign_fail(conn,
				 GSM0808_CAUSE_RADIO_INTERFACE_FAILURE,
				 NULL);
	}

	/* clear the connection now */
	if (bsc->clear_request)
		destruct = bsc->clear_request(conn, 0);

	/* now give up all channels */
	if (conn->lchan == lchan)
		conn->lchan = NULL;
	if (conn->ho_lchan == lchan) {
		bsc_clear_handover(conn, 0);
		conn->ho_lchan = NULL;
	}
	lchan->conn = NULL;

	gsm0808_clear(conn);

	if (destruct)
		subscr_con_free(conn);
}

static void handle_chan_ack(struct gsm_subscriber_connection *conn,
			    struct bsc_api *api, struct gsm_lchan *lchan)
{
	if (conn->secondary_lchan != lchan)
		return;

	LOGP(DMSC, LOGL_NOTICE, "Sending assignment on chan: %p\n", lchan);
	gsm48_send_rr_ass_cmd(conn->lchan, lchan, lchan->ms_power);
}

static void handle_chan_nack(struct gsm_subscriber_connection *conn,
			     struct bsc_api *api, struct gsm_lchan *lchan)
{
	if (conn->secondary_lchan != lchan)
		return;

	LOGP(DMSC, LOGL_ERROR, "Channel activation failed. Waiting for timeout now\n");
	conn->secondary_lchan->conn = NULL;
	conn->secondary_lchan = NULL;
}

static __attribute__((constructor)) void on_dso_load_bsc(void)
{
	osmo_signal_register_handler(SS_LCHAN, bsc_handle_lchan_signal, NULL);
}