summaryrefslogtreecommitdiffstats
path: root/openbsc/src/libgb/gprs_bssgp.c
blob: e93b3de9a5c599eb433ad3132b9d2921b0756b69 (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
/* GPRS BSSGP protocol implementation as per 3GPP TS 08.18 */

/* (C) 2009-2010 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/>.
 *
 * TODO:
 *  o  properly count incoming BVC-RESET packets in counter group
 *  o  set log context as early as possible for outgoing packets
 */

#include <errno.h>
#include <stdint.h>

#include <netinet/in.h>

#include <osmocom/core/msgb.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/rate_ctr.h>

#include <openbsc/debug.h>
#include <openbsc/gsm_data.h>
#include <openbsc/gsm_04_08_gprs.h>

#include <osmocom/gprs/gprs_bssgp.h>
#include <osmocom/gprs/gprs_ns.h>

#include <openbsc/gprs_gmm.h>

void *bssgp_tall_ctx = NULL;

static const struct rate_ctr_desc bssgp_ctr_description[] = {
	{ "packets.in",	"Packets at BSSGP Level ( In)" },
	{ "packets.out","Packets at BSSGP Level (Out)" },
	{ "bytes.in",	"Bytes at BSSGP Level   ( In)" },
	{ "bytes.out",	"Bytes at BSSGP Level   (Out)" },
	{ "blocked",	"BVC Blocking count" },
	{ "discarded",	"BVC LLC Discarded count" },
};

static const struct rate_ctr_group_desc bssgp_ctrg_desc = {
	.group_name_prefix = "bssgp.bss_ctx",
	.group_description = "BSSGP Peer Statistics",
	.num_ctr = ARRAY_SIZE(bssgp_ctr_description),
	.ctr_desc = bssgp_ctr_description,
};

LLIST_HEAD(bssgp_bvc_ctxts);

/* Find a BTS Context based on parsed RA ID and Cell ID */
struct bssgp_bvc_ctx *btsctx_by_raid_cid(const struct gprs_ra_id *raid, uint16_t cid)
{
	struct bssgp_bvc_ctx *bctx;

	llist_for_each_entry(bctx, &bssgp_bvc_ctxts, list) {
		if (!memcmp(&bctx->ra_id, raid, sizeof(bctx->ra_id)) &&
		    bctx->cell_id == cid)
			return bctx;
	}
	return NULL;
}

/* Find a BTS context based on BVCI+NSEI tuple */
struct bssgp_bvc_ctx *btsctx_by_bvci_nsei(uint16_t bvci, uint16_t nsei)
{
	struct bssgp_bvc_ctx *bctx;

	llist_for_each_entry(bctx, &bssgp_bvc_ctxts, list) {
		if (bctx->nsei == nsei && bctx->bvci == bvci)
			return bctx;
	}
	return NULL;
}

struct bssgp_bvc_ctx *btsctx_alloc(uint16_t bvci, uint16_t nsei)
{
	struct bssgp_bvc_ctx *ctx;

	ctx = talloc_zero(bssgp_tall_ctx, struct bssgp_bvc_ctx);
	if (!ctx)
		return NULL;
	ctx->bvci = bvci;
	ctx->nsei = nsei;
	/* FIXME: BVCI is not unique, only BVCI+NSEI ?!? */
	ctx->ctrg = rate_ctr_group_alloc(ctx, &bssgp_ctrg_desc, bvci);

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

	return ctx;
}

/* Chapter 10.4.5: Flow Control BVC ACK */
static int bssgp_tx_fc_bvc_ack(uint16_t nsei, uint8_t tag, uint16_t ns_bvci)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = ns_bvci;

	bgph->pdu_type = BSSGP_PDUT_FLOW_CONTROL_BVC_ACK;
	msgb_tvlv_put(msg, BSSGP_IE_TAG, 1, &tag);

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

/* 10.3.7 SUSPEND-ACK PDU */
int bssgp_tx_suspend_ack(uint16_t nsei, uint32_t tlli,
			 const struct gprs_ra_id *ra_id, uint8_t suspend_ref)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
		(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
	uint32_t _tlli;
	uint8_t ra[6];

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = 0; /* Signalling */
	bgph->pdu_type = BSSGP_PDUT_SUSPEND_ACK;

	_tlli = htonl(tlli);
	msgb_tvlv_put(msg, BSSGP_IE_TLLI, 4, (uint8_t *) &_tlli);
	gsm48_construct_ra(ra, ra_id);
	msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);
	msgb_tvlv_put(msg, BSSGP_IE_SUSPEND_REF_NR, 1, &suspend_ref);

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

/* 10.3.8 SUSPEND-NACK PDU */
int bssgp_tx_suspend_nack(uint16_t nsei, uint32_t tlli,
			  const struct gprs_ra_id *ra_id,
			  uint8_t *cause)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
		(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
	uint32_t _tlli;
	uint8_t ra[6];

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = 0; /* Signalling */
	bgph->pdu_type = BSSGP_PDUT_SUSPEND_NACK;

	_tlli = htonl(tlli);
	msgb_tvlv_put(msg, BSSGP_IE_TLLI, 4, (uint8_t *) &_tlli);
	gsm48_construct_ra(ra, ra_id);
	msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);
	if (cause)
		msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, cause);

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

/* 10.3.10 RESUME-ACK PDU */
int bssgp_tx_resume_ack(uint16_t nsei, uint32_t tlli,
			const struct gprs_ra_id *ra_id)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
		(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
	uint32_t _tlli;
	uint8_t ra[6];

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = 0; /* Signalling */
	bgph->pdu_type = BSSGP_PDUT_RESUME_ACK;

	_tlli = htonl(tlli);
	msgb_tvlv_put(msg, BSSGP_IE_TLLI, 4, (uint8_t *) &_tlli);
	gsm48_construct_ra(ra, ra_id);
	msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

/* 10.3.11 RESUME-NACK PDU */
int bssgp_tx_resume_nack(uint16_t nsei, uint32_t tlli,
			 const struct gprs_ra_id *ra_id, uint8_t *cause)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
		(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
	uint32_t _tlli;
	uint8_t ra[6];

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = 0; /* Signalling */
	bgph->pdu_type = BSSGP_PDUT_SUSPEND_NACK;

	_tlli = htonl(tlli);
	msgb_tvlv_put(msg, BSSGP_IE_TLLI, 4, (uint8_t *) &_tlli);
	gsm48_construct_ra(ra, ra_id);
	msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);
	if (cause)
		msgb_tvlv_put(msg, BSSGP_IE_CAUSE, 1, cause);

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

uint16_t bssgp_parse_cell_id(struct gprs_ra_id *raid, const uint8_t *buf)
{
	/* 6 octets RAC */
	gsm48_parse_ra(raid, buf);
	/* 2 octets CID */
	return ntohs(*(uint16_t *) (buf+6));
}

int bssgp_create_cell_id(uint8_t *buf, const struct gprs_ra_id *raid,
			 uint16_t cid)
{
	uint16_t *out_cid = (uint16_t *) (buf + 6);
	/* 6 octets RAC */
	gsm48_construct_ra(buf, raid);
	/* 2 octets CID */
	*out_cid = htons(cid);

	return 8;
}

/* Chapter 8.4 BVC-Reset Procedure */
static int bssgp_rx_bvc_reset(struct msgb *msg, struct tlv_parsed *tp,	
			      uint16_t ns_bvci)
{
	struct bssgp_bvc_ctx *bctx;
	uint16_t nsei = msgb_nsei(msg);
	uint16_t bvci;
	int rc;

	bvci = ntohs(*(uint16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
	DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx RESET cause=%s\n", bvci,
		bssgp_cause_str(*TLVP_VAL(tp, BSSGP_IE_CAUSE)));

	/* look-up or create the BTS context for this BVC */
	bctx = btsctx_by_bvci_nsei(bvci, nsei);
	if (!bctx)
		bctx = btsctx_alloc(bvci, nsei);

	/* As opposed to NS-VCs, BVCs are NOT blocked after RESET */
	bctx->state &= ~BVC_S_BLOCKED;

	/* When we receive a BVC-RESET PDU (at least of a PTP BVCI), the BSS
	 * informs us about its RAC + Cell ID, so we can create a mapping */
	if (bvci != 0 && bvci != 1) {
		if (!TLVP_PRESENT(tp, BSSGP_IE_CELL_ID)) {
			LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx RESET "
				"missing mandatory IE\n", bvci);
			return -EINVAL;
		}
		/* actually extract RAC / CID */
		bctx->cell_id = bssgp_parse_cell_id(&bctx->ra_id,
						TLVP_VAL(tp, BSSGP_IE_CELL_ID));
		LOGP(DBSSGP, LOGL_NOTICE, "Cell %u-%u-%u-%u CI %u on BVCI %u\n",
			bctx->ra_id.mcc, bctx->ra_id.mnc, bctx->ra_id.lac,
			bctx->ra_id.rac, bctx->cell_id, bvci);
	}

	/* Acknowledge the RESET to the BTS */
	rc = bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_RESET_ACK,
				  nsei, bvci, ns_bvci);
	return 0;
}

static int bssgp_rx_bvc_block(struct msgb *msg, struct tlv_parsed *tp)
{
	uint16_t bvci;
	struct bssgp_bvc_ctx *ptp_ctx;

	bvci = ntohs(*(uint16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
	if (bvci == BVCI_SIGNALLING) {
		/* 8.3.2: Signalling BVC shall never be blocked */
		LOGP(DBSSGP, LOGL_ERROR, "NSEI=%u/BVCI=%u "
			"received block for signalling BVC!?!\n",
			msgb_nsei(msg), msgb_bvci(msg));
		return 0;
	}

	LOGP(DBSSGP, LOGL_INFO, "BSSGP Rx BVCI=%u BVC-BLOCK\n", bvci);

	ptp_ctx = btsctx_by_bvci_nsei(bvci, msgb_nsei(msg));
	if (!ptp_ctx)
		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, &bvci, msg);

	ptp_ctx->state |= BVC_S_BLOCKED;
	rate_ctr_inc(&ptp_ctx->ctrg->ctr[BSSGP_CTR_BLOCKED]);

	/* FIXME: Send NM_BVC_BLOCK.ind to NM */

	/* We always acknowledge the BLOCKing */
	return bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_BLOCK_ACK, msgb_nsei(msg),
				    bvci, msgb_bvci(msg));
};

static int bssgp_rx_bvc_unblock(struct msgb *msg, struct tlv_parsed *tp)
{
	uint16_t bvci;
	struct bssgp_bvc_ctx *ptp_ctx;

	bvci = ntohs(*(uint16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
	if (bvci == BVCI_SIGNALLING) {
		/* 8.3.2: Signalling BVC shall never be blocked */
		LOGP(DBSSGP, LOGL_ERROR, "NSEI=%u/BVCI=%u "
			"received unblock for signalling BVC!?!\n",
			msgb_nsei(msg), msgb_bvci(msg));
		return 0;
	}

	DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx BVC-UNBLOCK\n", bvci);

	ptp_ctx = btsctx_by_bvci_nsei(bvci, msgb_nsei(msg));
	if (!ptp_ctx)
		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, &bvci, msg);

	ptp_ctx->state &= ~BVC_S_BLOCKED;

	/* FIXME: Send NM_BVC_UNBLOCK.ind to NM */

	/* We always acknowledge the unBLOCKing */
	return bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_UNBLOCK_ACK, msgb_nsei(msg),
				    bvci, msgb_bvci(msg));
};

/* Uplink unit-data */
static int bssgp_rx_ul_ud(struct msgb *msg, struct tlv_parsed *tp,
			  struct bssgp_bvc_ctx *ctx)
{
	struct bssgp_ud_hdr *budh = (struct bssgp_ud_hdr *) msgb_bssgph(msg);

	/* extract TLLI and parse TLV IEs */
	msgb_tlli(msg) = ntohl(budh->tlli);

	DEBUGP(DBSSGP, "BSSGP TLLI=0x%08x Rx UPLINK-UNITDATA\n", msgb_tlli(msg));

	/* Cell ID and LLC_PDU are the only mandatory IE */
	if (!TLVP_PRESENT(tp, BSSGP_IE_CELL_ID) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_LLC_PDU)) {
		LOGP(DBSSGP, LOGL_ERROR, "BSSGP TLLI=0x%08x Rx UL-UD "
			"missing mandatory IE\n", msgb_tlli(msg));
		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
	}

	/* store pointer to LLC header and CELL ID in msgb->cb */
	msgb_llch(msg) = (uint8_t *) TLVP_VAL(tp, BSSGP_IE_LLC_PDU);
	msgb_bcid(msg) = (uint8_t *) TLVP_VAL(tp, BSSGP_IE_CELL_ID);

	return gprs_llc_rcvmsg(msg, tp);
}

static int bssgp_rx_suspend(struct msgb *msg, struct tlv_parsed *tp,
			    struct bssgp_bvc_ctx *ctx)
{
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_bssgph(msg);
	struct gprs_ra_id raid;
	uint32_t tlli;
	int rc;

	if (!TLVP_PRESENT(tp, BSSGP_IE_TLLI) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
		LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx SUSPEND "
			"missing mandatory IE\n", ctx->bvci);
		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
	}

	tlli = ntohl(*(uint32_t *)TLVP_VAL(tp, BSSGP_IE_TLLI));

	DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=0x%08x Rx SUSPEND\n",
		ctx->bvci, tlli);

	gsm48_parse_ra(&raid, TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));

	/* Inform GMM about the SUSPEND request */
	rc = gprs_gmm_rx_suspend(&raid, tlli);
	if (rc < 0)
		return bssgp_tx_suspend_nack(msgb_nsei(msg), tlli, &raid, NULL);

	bssgp_tx_suspend_ack(msgb_nsei(msg), tlli, &raid, 0);

	return 0;
}

static int bssgp_rx_resume(struct msgb *msg, struct tlv_parsed *tp,
			   struct bssgp_bvc_ctx *ctx)
{
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_bssgph(msg);
	struct gprs_ra_id raid;
	uint32_t tlli;
	uint8_t suspend_ref;
	int rc;

	if (!TLVP_PRESENT(tp, BSSGP_IE_TLLI) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_SUSPEND_REF_NR)) {
		LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx RESUME "
			"missing mandatory IE\n", ctx->bvci);
		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
	}

	tlli = ntohl(*(uint32_t *)TLVP_VAL(tp, BSSGP_IE_TLLI));
	suspend_ref = *TLVP_VAL(tp, BSSGP_IE_SUSPEND_REF_NR);

	DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=0x%08x Rx RESUME\n", ctx->bvci, tlli);

	gsm48_parse_ra(&raid, TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));

	/* Inform GMM about the RESUME request */
	rc = gprs_gmm_rx_resume(&raid, tlli, suspend_ref);
	if (rc < 0)
		return bssgp_tx_resume_nack(msgb_nsei(msg), tlli, &raid,
					    NULL);

	bssgp_tx_resume_ack(msgb_nsei(msg), tlli, &raid);
	return 0;
}


static int bssgp_rx_llc_disc(struct msgb *msg, struct tlv_parsed *tp,
			     struct bssgp_bvc_ctx *ctx)
{
	uint32_t tlli = 0;

	if (!TLVP_PRESENT(tp, BSSGP_IE_TLLI) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_LLC_FRAMES_DISCARDED) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_BVCI) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_NUM_OCT_AFF)) {
		LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx LLC DISCARDED "
			"missing mandatory IE\n", ctx->bvci);
	}

	if (TLVP_PRESENT(tp, BSSGP_IE_TLLI))
		tlli = ntohl(*(uint32_t *)TLVP_VAL(tp, BSSGP_IE_TLLI));

	DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=%08x Rx LLC DISCARDED\n",
		ctx->bvci, tlli);

	rate_ctr_inc(&ctx->ctrg->ctr[BSSGP_CTR_DISCARDED]);

	/* FIXME: send NM_LLC_DISCARDED to NM */
	return 0;
}

static int bssgp_rx_fc_bvc(struct msgb *msg, struct tlv_parsed *tp,
			   struct bssgp_bvc_ctx *bctx)
{

	DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx Flow Control BVC\n",
		bctx->bvci);

	if (!TLVP_PRESENT(tp, BSSGP_IE_TAG) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_BVC_BUCKET_SIZE) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_BUCKET_LEAK_RATE) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_BMAX_DEFAULT_MS) ||
	    !TLVP_PRESENT(tp, BSSGP_IE_R_DEFAULT_MS)) {
		LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx FC BVC "
			"missing mandatory IE\n", bctx->bvci);
		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
	}

	/* FIXME: actually implement flow control */

	/* Send FLOW_CONTROL_BVC_ACK */
	return bssgp_tx_fc_bvc_ack(msgb_nsei(msg), *TLVP_VAL(tp, BSSGP_IE_TAG),
				   msgb_bvci(msg));
}

/* Receive a BSSGP PDU from a BSS on a PTP BVCI */
static int gprs_bssgp_rx_ptp(struct msgb *msg, struct tlv_parsed *tp,
			     struct bssgp_bvc_ctx *bctx)
{
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_bssgph(msg);
	uint8_t pdu_type = bgph->pdu_type;
	int rc = 0;

	/* If traffic is received on a BVC that is marked as blocked, the
	 * received PDU shall not be accepted and a STATUS PDU (Cause value:
	 * BVC Blocked) shall be sent to the peer entity on the signalling BVC */
	if (bctx->state & BVC_S_BLOCKED && pdu_type != BSSGP_PDUT_STATUS) {
		uint16_t bvci = msgb_bvci(msg);
		return bssgp_tx_status(BSSGP_CAUSE_BVCI_BLOCKED, &bvci, msg);
	}

	switch (pdu_type) {
	case BSSGP_PDUT_UL_UNITDATA:
		/* some LLC data from the MS */
		rc = bssgp_rx_ul_ud(msg, tp, bctx);
		break;
	case BSSGP_PDUT_RA_CAPABILITY:
		/* BSS requests RA capability or IMSI */
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx RA CAPABILITY UPDATE\n",
			bctx->bvci);
		/* FIXME: send GMM_RA_CAPABILITY_UPDATE.ind to GMM */
		/* FIXME: send RA_CAPA_UPDATE_ACK */
		break;
	case BSSGP_PDUT_RADIO_STATUS:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx RADIO STATUS\n", bctx->bvci);
		/* BSS informs us of some exception */
		/* FIXME: send GMM_RADIO_STATUS.ind to GMM */
		break;
	case BSSGP_PDUT_FLOW_CONTROL_BVC:
		/* BSS informs us of available bandwidth in Gb interface */
		rc = bssgp_rx_fc_bvc(msg, tp, bctx);
		break;
	case BSSGP_PDUT_FLOW_CONTROL_MS:
		/* BSS informs us of available bandwidth to one MS */
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx Flow Control MS\n",
			bctx->bvci);
		/* FIXME: actually implement flow control */
		/* FIXME: Send FLOW_CONTROL_MS_ACK */
		break;
	case BSSGP_PDUT_STATUS:
		/* Some exception has occurred */
		/* FIXME: send NM_STATUS.ind to NM */
	case BSSGP_PDUT_DOWNLOAD_BSS_PFC:
	case BSSGP_PDUT_CREATE_BSS_PFC_ACK:
	case BSSGP_PDUT_CREATE_BSS_PFC_NACK:
	case BSSGP_PDUT_MODIFY_BSS_PFC:
	case BSSGP_PDUT_DELETE_BSS_PFC_ACK:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx PDU type 0x%02x not [yet] "
			"implemented\n", bctx->bvci, pdu_type);
		rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, msg);
		break;
	/* those only exist in the SGSN -> BSS direction */
	case BSSGP_PDUT_DL_UNITDATA:
	case BSSGP_PDUT_PAGING_PS:
	case BSSGP_PDUT_PAGING_CS:
	case BSSGP_PDUT_RA_CAPA_UPDATE_ACK:
	case BSSGP_PDUT_FLOW_CONTROL_BVC_ACK:
	case BSSGP_PDUT_FLOW_CONTROL_MS_ACK:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u PDU type 0x%02x only exists "
			"in DL\n", bctx->bvci, pdu_type);
		bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
		rc = -EINVAL;
		break;
	default:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u PDU type 0x%02x unknown\n",
			bctx->bvci, pdu_type);
		rc = bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
		break;
	}

	return rc;
}

/* Receive a BSSGP PDU from a BSS on a SIGNALLING BVCI */
static int gprs_bssgp_rx_sign(struct msgb *msg, struct tlv_parsed *tp,
				struct bssgp_bvc_ctx *bctx)
{
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_bssgph(msg);
	uint8_t pdu_type = bgph->pdu_type;
	int rc = 0;
	uint16_t ns_bvci = msgb_bvci(msg);
	uint16_t bvci;

	switch (bgph->pdu_type) {
	case BSSGP_PDUT_SUSPEND:
		/* MS wants to suspend */
		rc = bssgp_rx_suspend(msg, tp, bctx);
		break;
	case BSSGP_PDUT_RESUME:
		/* MS wants to resume */
		rc = bssgp_rx_resume(msg, tp, bctx);
		break;
	case BSSGP_PDUT_FLUSH_LL_ACK:
		/* BSS informs us it has performed LL FLUSH */
		DEBUGP(DBSSGP, "BSSGP Rx BVCI=%u FLUSH LL ACK\n", bctx->bvci);
		/* FIXME: send NM_FLUSH_LL.res to NM */
		break;
	case BSSGP_PDUT_LLC_DISCARD:
		/* BSS informs that some LLC PDU's have been discarded */
		rc = bssgp_rx_llc_disc(msg, tp, bctx);
		break;
	case BSSGP_PDUT_BVC_BLOCK:
		/* BSS tells us that BVC shall be blocked */
		if (!TLVP_PRESENT(tp, BSSGP_IE_BVCI) ||
		    !TLVP_PRESENT(tp, BSSGP_IE_CAUSE)) {
			LOGP(DBSSGP, LOGL_ERROR, "BSSGP Rx BVC-BLOCK "
				"missing mandatory IE\n");
			goto err_mand_ie;
		}
		rc = bssgp_rx_bvc_block(msg, tp);
		break;
	case BSSGP_PDUT_BVC_UNBLOCK:
		/* BSS tells us that BVC shall be unblocked */
		if (!TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
			LOGP(DBSSGP, LOGL_ERROR, "BSSGP Rx BVC-UNBLOCK "
				"missing mandatory IE\n");
			goto err_mand_ie;
		}
		rc = bssgp_rx_bvc_unblock(msg, tp);
		break;
	case BSSGP_PDUT_BVC_RESET:
		/* BSS tells us that BVC init is required */
		if (!TLVP_PRESENT(tp, BSSGP_IE_BVCI) ||
		    !TLVP_PRESENT(tp, BSSGP_IE_CAUSE)) {
			LOGP(DBSSGP, LOGL_ERROR, "BSSGP Rx BVC-RESET "
				"missing mandatory IE\n");
			goto err_mand_ie;
		}
		rc = bssgp_rx_bvc_reset(msg, tp, ns_bvci);
		break;
	case BSSGP_PDUT_STATUS:
		/* Some exception has occurred */
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx BVC STATUS\n", bctx->bvci);
		/* FIXME: send NM_STATUS.ind to NM */
		break;
	/* those only exist in the SGSN -> BSS direction */
	case BSSGP_PDUT_PAGING_PS:
	case BSSGP_PDUT_PAGING_CS:
	case BSSGP_PDUT_SUSPEND_ACK:
	case BSSGP_PDUT_SUSPEND_NACK:
	case BSSGP_PDUT_RESUME_ACK:
	case BSSGP_PDUT_RESUME_NACK:
	case BSSGP_PDUT_FLUSH_LL:
	case BSSGP_PDUT_BVC_BLOCK_ACK:
	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
	case BSSGP_PDUT_SGSN_INVOKE_TRACE:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx PDU type 0x%02x only exists "
			"in DL\n", bctx->bvci, pdu_type);
		bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
		rc = -EINVAL;
		break;
	default:
		DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx PDU type 0x%02x unknown\n",
			bctx->bvci, pdu_type);
		rc = bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
		break;
	}

	return rc;
err_mand_ie:
	return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
}

/* We expect msgb_bssgph() to point to the BSSGP header */
int gprs_bssgp_rcvmsg(struct msgb *msg)
{
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_bssgph(msg);
	struct bssgp_ud_hdr *budh = (struct bssgp_ud_hdr *) msgb_bssgph(msg);
	struct tlv_parsed tp;
	struct bssgp_bvc_ctx *bctx;
	uint8_t pdu_type = bgph->pdu_type;
	uint16_t ns_bvci = msgb_bvci(msg);
	int data_len;
	int rc = 0;

	/* Identifiers from DOWN: NSEI, BVCI (both in msg->cb) */

	/* UNITDATA BSSGP headers have TLLI in front */
	if (pdu_type != BSSGP_PDUT_UL_UNITDATA &&
	    pdu_type != BSSGP_PDUT_DL_UNITDATA) {
		data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
		rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
	} else {
		data_len = msgb_bssgp_len(msg) - sizeof(*budh);
		rc = bssgp_tlv_parse(&tp, budh->data, data_len);
	}

	/* look-up or create the BTS context for this BVC */
	bctx = btsctx_by_bvci_nsei(ns_bvci, msgb_nsei(msg));
	/* Only a RESET PDU can create a new BVC context */
	if (!bctx && pdu_type != BSSGP_PDUT_BVC_RESET) {
		LOGP(DBSSGP, LOGL_NOTICE, "NSEI=%u/BVCI=%u Rejecting PDU "
			"type %u for unknown BVCI\n", msgb_nsei(msg), ns_bvci,
			pdu_type);
		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, NULL, msg);
	}

	if (bctx) {
		log_set_context(BSC_CTX_BVC, bctx);
		rate_ctr_inc(&bctx->ctrg->ctr[BSSGP_CTR_PKTS_IN]);
		rate_ctr_add(&bctx->ctrg->ctr[BSSGP_CTR_BYTES_IN],
			     msgb_bssgp_len(msg));
	}

	if (ns_bvci == BVCI_SIGNALLING)
		rc = gprs_bssgp_rx_sign(msg, &tp, bctx);
	else if (ns_bvci == BVCI_PTM)
		rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, msg);
	else
		rc = gprs_bssgp_rx_ptp(msg, &tp, bctx);

	return rc;
}

/* Entry function from upper level (LLC), asking us to transmit a BSSGP PDU
 * to a remote MS (identified by TLLI) at a BTS identified by its BVCI and NSEI */
int gprs_bssgp_tx_dl_ud(struct msgb *msg, struct sgsn_mm_ctx *mmctx)
{
	struct bssgp_bvc_ctx *bctx;
	struct bssgp_ud_hdr *budh;
	uint8_t llc_pdu_tlv_hdr_len = 2;
	uint8_t *llc_pdu_tlv, *qos_profile;
	uint16_t pdu_lifetime = 1000; /* centi-seconds */
	uint8_t qos_profile_default[3] = { 0x00, 0x00, 0x20 };
	uint16_t msg_len = msg->len;
	uint16_t bvci = msgb_bvci(msg);
	uint16_t nsei = msgb_nsei(msg);
	uint16_t drx_params;

	/* Identifiers from UP: TLLI, BVCI, NSEI (all in msgb->cb) */
	if (bvci <= BVCI_PTM ) {
		LOGP(DBSSGP, LOGL_ERROR, "Cannot send DL-UD to BVCI %u\n",
			bvci);
		return -EINVAL;
	}

	bctx = btsctx_by_bvci_nsei(bvci, nsei);
	if (!bctx) {
		/* FIXME: don't simply create missing context, but reject message */
		bctx = btsctx_alloc(bvci, nsei);
	}

	if (msg->len > TVLV_MAX_ONEBYTE)
		llc_pdu_tlv_hdr_len += 1;

	/* prepend the tag and length of the LLC-PDU TLV */
	llc_pdu_tlv = msgb_push(msg, llc_pdu_tlv_hdr_len);
	llc_pdu_tlv[0] = BSSGP_IE_LLC_PDU;
	if (llc_pdu_tlv_hdr_len > 2) {
		llc_pdu_tlv[1] = msg_len >> 8;
		llc_pdu_tlv[2] = msg_len & 0xff;
	} else {
		llc_pdu_tlv[1] = msg_len & 0x7f;
		llc_pdu_tlv[1] |= 0x80;
	}

	/* FIXME: optional elements: Alignment, UTRAN CCO, LSA, PFI */

	if (mmctx) {
		/* Old TLLI to help BSS map from old->new */
#if 0
		if (mmctx->tlli_old)
			msgb_tvlv_push(msg, BSSGP_IE_TLLI, 4, htonl(*tlli_old));
#endif

		/* IMSI */
		if (strlen(mmctx->imsi)) {
			uint8_t mi[10];
			int imsi_len = gsm48_generate_mid_from_imsi(mi, mmctx->imsi);
			if (imsi_len > 2)
				msgb_tvlv_push(msg, BSSGP_IE_IMSI,
							imsi_len-2, mi+2);
		}

		/* DRX parameters */
		drx_params = htons(mmctx->drx_parms);
		msgb_tvlv_push(msg, BSSGP_IE_DRX_PARAMS, 2,
				(uint8_t *) &drx_params);

		/* FIXME: Priority */

		/* MS Radio Access Capability */
		if (mmctx->ms_radio_access_capa.len)
			msgb_tvlv_push(msg, BSSGP_IE_MS_RADIO_ACCESS_CAP,
					mmctx->ms_radio_access_capa.len,
					mmctx->ms_radio_access_capa.buf);
	}

	/* prepend the pdu lifetime */
	pdu_lifetime = htons(pdu_lifetime);
	msgb_tvlv_push(msg, BSSGP_IE_PDU_LIFETIME, 2, (uint8_t *)&pdu_lifetime);

	/* prepend the QoS profile, TLLI and pdu type */
	budh = (struct bssgp_ud_hdr *) msgb_push(msg, sizeof(*budh));
	memcpy(budh->qos_profile, qos_profile_default, sizeof(qos_profile_default));
	budh->tlli = htonl(msgb_tlli(msg));
	budh->pdu_type = BSSGP_PDUT_DL_UNITDATA;

	rate_ctr_inc(&bctx->ctrg->ctr[BSSGP_CTR_PKTS_OUT]);
	rate_ctr_add(&bctx->ctrg->ctr[BSSGP_CTR_BYTES_OUT], msg->len);

	/* Identifiers down: BVCI, NSEI (in msgb->cb) */

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}

/* Send a single GMM-PAGING.req to a given NSEI/NS-BVCI */
int gprs_bssgp_tx_paging(uint16_t nsei, uint16_t ns_bvci,
			 struct bssgp_paging_info *pinfo)
{
	struct msgb *msg = bssgp_msgb_alloc();
	struct bssgp_normal_hdr *bgph =
			(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
	uint16_t drx_params = htons(pinfo->drx_params);
	uint8_t mi[10];
	int imsi_len = gsm48_generate_mid_from_imsi(mi, pinfo->imsi);
	uint8_t ra[6];

	if (imsi_len < 2)
		return -EINVAL;

	msgb_nsei(msg) = nsei;
	msgb_bvci(msg) = ns_bvci;

	if (pinfo->mode == BSSGP_PAGING_PS)
		bgph->pdu_type = BSSGP_PDUT_PAGING_PS;
	else
		bgph->pdu_type = BSSGP_PDUT_PAGING_CS;
	/* IMSI */
	msgb_tvlv_put(msg, BSSGP_IE_IMSI, imsi_len-2, mi+2);
	/* DRX Parameters */
	msgb_tvlv_put(msg, BSSGP_IE_DRX_PARAMS, 2,
			(uint8_t *) &drx_params);
	/* Scope */
	switch (pinfo->scope) {
	case BSSGP_PAGING_BSS_AREA:
		{
			uint8_t null = 0;
			msgb_tvlv_put(msg, BSSGP_IE_BSS_AREA_ID, 1, &null);
		}
		break;
	case BSSGP_PAGING_LOCATION_AREA:
		gsm48_construct_ra(ra, &pinfo->raid);
		msgb_tvlv_put(msg, BSSGP_IE_LOCATION_AREA, 4, ra);
		break;
	case BSSGP_PAGING_ROUTEING_AREA:
		gsm48_construct_ra(ra, &pinfo->raid);
		msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);
		break;
	case BSSGP_PAGING_BVCI:
		{
			uint16_t bvci = htons(pinfo->bvci);
			msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *)&bvci);
		}
		break;
	}
	/* QoS profile mandatory for PS */
	if (pinfo->mode == BSSGP_PAGING_PS)
		msgb_tvlv_put(msg, BSSGP_IE_QOS_PROFILE, 3, pinfo->qos);

	/* Optional (P-)TMSI */
	if (pinfo->ptmsi) {
		uint32_t ptmsi = htonl(*pinfo->ptmsi);
		msgb_tvlv_put(msg, BSSGP_IE_TMSI, 4, (uint8_t *) &ptmsi);
	}

	return gprs_ns_sendmsg(bssgp_nsi, msg);
}