summaryrefslogtreecommitdiffstats
path: root/openbsc/src/libgb/gprs_ns.c
blob: cdee833821584e6cf9aa90436190beda44522da7 (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
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
/* GPRS Networks Service (NS) messages on the Gb interface
 * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05) */

/* (C) 2009-2012 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/>.
 *
 */

/*! \addtogroup libgb
 *  @{
 */

/*! \file gprs_ns.c */

/*!
 * GPRS Networks Service (NS) messages on the Gb interface
 * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05) 
 *
 * Some introduction into NS:  NS is used typically on top of frame relay,
 * but in the ip.access world it is encapsulated in UDP packets.  It serves
 * as an intermediate shim betwen BSSGP and the underlying medium.  It doesn't
 * do much, apart from providing congestion notification and status indication.
 *
 * Terms:
 * 	NS		Network Service
 *	NSVC		NS Virtual Connection
 *	NSEI		NS Entity Identifier
 *	NSVL		NS Virtual Link
 *	NSVLI		NS Virtual Link Identifier
 *	BVC		BSSGP Virtual Connection
 *	BVCI		BSSGP Virtual Connection Identifier
 *	NSVCG		NS Virtual Connection Goup
 *	Blocked		NS-VC cannot be used for user traffic
 *	Alive		Ability of a NS-VC to provide communication
 *
 *  There can be multiple BSSGP virtual connections over one (group of) NSVC's.  BSSGP will
 * therefore identify the BSSGP virtual connection by a BVCI passed down to NS.
 * NS then has to firgure out which NSVC's are responsible for this BVCI.
 * Those mappings are administratively configured.
 */

/* This implementation has the following limitations:
 *  o Only one NS-VC for each NSE: No load-sharing function
 *  o NSVCI 65535 and 65534 are reserved for internal use
 *  o Only UDP is supported as of now, no frame relay support
 *  o The IP Sub-Network-Service (SNS) as specified in 48.016 is not implemented
 *  o There are no BLOCK and UNBLOCK timers (yet?)
 */

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

#include <arpa/inet.h>

#include <osmocom/core/msgb.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/select.h>
#include <osmocom/core/rate_ctr.h>
#include <osmocom/core/socket.h>
#include <osmocom/core/signal.h>
#include <osmocom/gprs/gprs_ns.h>
#include <osmocom/gprs/gprs_bssgp.h>
#include <osmocom/gprs/gprs_ns_frgre.h>

#include "common_vty.h"

static const struct tlv_definition ns_att_tlvdef = {
	.def = {
		[NS_IE_CAUSE]	= { TLV_TYPE_TvLV, 0 },
		[NS_IE_VCI]	= { TLV_TYPE_TvLV, 0 },
		[NS_IE_PDU]	= { TLV_TYPE_TvLV, 0 },
		[NS_IE_BVCI]	= { TLV_TYPE_TvLV, 0 },
		[NS_IE_NSEI]	= { TLV_TYPE_TvLV, 0 },
	},
};

enum ns_ctr {
	NS_CTR_PKTS_IN,
	NS_CTR_PKTS_OUT,
	NS_CTR_BYTES_IN,
	NS_CTR_BYTES_OUT,
	NS_CTR_BLOCKED,
	NS_CTR_DEAD,
};

static const struct rate_ctr_desc nsvc_ctr_description[] = {
	{ "packets.in", "Packets at NS Level ( In)" },
	{ "packets.out","Packets at NS Level (Out)" },
	{ "bytes.in",	"Bytes at NS Level   ( In)" },
	{ "bytes.out",	"Bytes at NS Level   (Out)" },
	{ "blocked",	"NS-VC Block count        " },
	{ "dead",	"NS-VC gone dead count    " },
};

static const struct rate_ctr_group_desc nsvc_ctrg_desc = {
	.group_name_prefix = "ns.nsvc",
	.group_description = "NSVC Peer Statistics",
	.num_ctr = ARRAY_SIZE(nsvc_ctr_description),
	.ctr_desc = nsvc_ctr_description,
};

/*! \brief Lookup struct gprs_nsvc based on NSVCI
 *  \param[in] nsi NS instance in which to search
 *  \param[in] nsvci NSVCI to be searched
 *  \returns gprs_nsvc of respective NSVCI
 */
struct gprs_nsvc *gprs_nsvc_by_nsvci(struct gprs_ns_inst *nsi, uint16_t nsvci)
{
	struct gprs_nsvc *nsvc;
	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
		if (nsvc->nsvci == nsvci)
			return nsvc;
	}
	return NULL;
}

/*! \brief Lookup struct gprs_nsvc based on NSEI
 *  \param[in] nsi NS instance in which to search
 *  \param[in] nsei NSEI to be searched
 *  \returns gprs_nsvc of respective NSEI
 */
struct gprs_nsvc *gprs_nsvc_by_nsei(struct gprs_ns_inst *nsi, uint16_t nsei)
{
	struct gprs_nsvc *nsvc;
	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
		if (nsvc->nsei == nsei)
			return nsvc;
	}
	return NULL;
}

/* Lookup struct gprs_nsvc based on remote peer socket addr */
static struct gprs_nsvc *nsvc_by_rem_addr(struct gprs_ns_inst *nsi,
					  struct sockaddr_in *sin)
{
	struct gprs_nsvc *nsvc;
	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
		if (nsvc->ip.bts_addr.sin_addr.s_addr ==
					sin->sin_addr.s_addr &&
		    nsvc->ip.bts_addr.sin_port == sin->sin_port)
			return nsvc;
	}
	return NULL;
}

static void gprs_ns_timer_cb(void *data);

struct gprs_nsvc *gprs_nsvc_create(struct gprs_ns_inst *nsi, uint16_t nsvci)
{
	struct gprs_nsvc *nsvc;

	LOGP(DNS, LOGL_INFO, "NSVCI=%u Creating NS-VC\n", nsvci);

	nsvc = talloc_zero(nsi, struct gprs_nsvc);
	nsvc->nsvci = nsvci;
	/* before RESET procedure: BLOCKED and DEAD */
	nsvc->state = NSE_S_BLOCKED;
	nsvc->nsi = nsi;
	nsvc->timer.cb = gprs_ns_timer_cb;
	nsvc->timer.data = nsvc;
	nsvc->ctrg = rate_ctr_group_alloc(nsvc, &nsvc_ctrg_desc, nsvci);

	llist_add(&nsvc->list, &nsi->gprs_nsvcs);

	return nsvc;
}

/*! \brief Delete given NS-VC
 *  \param[in] nsvc gprs_nsvc to be deleted
 */
void gprs_nsvc_delete(struct gprs_nsvc *nsvc)
{
	if (osmo_timer_pending(&nsvc->timer))
		osmo_timer_del(&nsvc->timer);
	llist_del(&nsvc->list);
	talloc_free(nsvc);
}

static void ns_osmo_signal_dispatch(struct gprs_nsvc *nsvc, unsigned int signal,
			       uint8_t cause)
{
	struct ns_signal_data nssd;

	nssd.nsvc = nsvc;
	nssd.cause = cause;

	osmo_signal_dispatch(SS_L_NS, signal, &nssd);
}

/* Section 10.3.2, Table 13 */
static const struct value_string ns_cause_str[] = {
	{ NS_CAUSE_TRANSIT_FAIL,	"Transit network failure" },
	{ NS_CAUSE_OM_INTERVENTION, 	"O&M intervention" },
	{ NS_CAUSE_EQUIP_FAIL,		"Equipment failure" },
	{ NS_CAUSE_NSVC_BLOCKED,	"NS-VC blocked" },
	{ NS_CAUSE_NSVC_UNKNOWN,	"NS-VC unknown" },
	{ NS_CAUSE_BVCI_UNKNOWN,	"BVCI unknown" },
	{ NS_CAUSE_SEM_INCORR_PDU,	"Semantically incorrect PDU" },
	{ NS_CAUSE_PDU_INCOMP_PSTATE,	"PDU not compatible with protocol state" },
	{ NS_CAUSE_PROTO_ERR_UNSPEC,	"Protocol error, unspecified" },
	{ NS_CAUSE_INVAL_ESSENT_IE,	"Invalid essential IE" },
	{ NS_CAUSE_MISSING_ESSENT_IE,	"Missing essential IE" },
	{ 0, NULL }
};

/*! \brief Obtain a human-readable string for NS cause value */
const char *gprs_ns_cause_str(enum ns_cause cause)
{
	return get_value_string(ns_cause_str, cause);
}

static int nsip_sendmsg(struct gprs_nsvc *nsvc, struct msgb *msg);
extern int grps_ns_frgre_sendmsg(struct gprs_nsvc *nsvc, struct msgb *msg);

static int gprs_ns_tx(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	int ret;

	log_set_context(GPRS_CTX_NSVC, nsvc);

	/* Increment number of Uplink bytes */
	rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_PKTS_OUT]);
	rate_ctr_add(&nsvc->ctrg->ctr[NS_CTR_BYTES_OUT], msgb_l2len(msg));

	switch (nsvc->ll) {
	case GPRS_NS_LL_UDP:
		ret = nsip_sendmsg(nsvc, msg);
		break;
	case GPRS_NS_LL_FR_GRE:
		ret = gprs_ns_frgre_sendmsg(nsvc, msg);
		break;
	default:
		LOGP(DNS, LOGL_ERROR, "unsupported NS linklayer %u\n", nsvc->ll);
		msgb_free(msg);
		ret = -EIO;
		break;
	}
	return ret;
}

static int gprs_ns_tx_simple(struct gprs_nsvc *nsvc, uint8_t pdu_type)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	struct gprs_ns_hdr *nsh;

	log_set_context(GPRS_CTX_NSVC, nsvc);

	if (!msg)
		return -ENOMEM;

	msg->l2h = msgb_put(msg, sizeof(*nsh));
	nsh = (struct gprs_ns_hdr *) msg->l2h;

	nsh->pdu_type = pdu_type;

	return gprs_ns_tx(nsvc, msg);
}

/*! \brief Transmit a NS-RESET on a given NSVC
 *  \param[in] nsvc NS-VC used for transmission
 *  \paam[in] cause Numeric NS cause value
 */
int gprs_ns_tx_reset(struct gprs_nsvc *nsvc, uint8_t cause)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	struct gprs_ns_hdr *nsh;
	uint16_t nsvci = htons(nsvc->nsvci);
	uint16_t nsei = htons(nsvc->nsei);

	log_set_context(GPRS_CTX_NSVC, nsvc);

	if (!msg)
		return -ENOMEM;

	LOGP(DNS, LOGL_INFO, "NSEI=%u Tx NS RESET (NSVCI=%u, cause=%s)\n",
		nsvc->nsei, nsvc->nsvci, gprs_ns_cause_str(cause));

	msg->l2h = msgb_put(msg, sizeof(*nsh));
	nsh = (struct gprs_ns_hdr *) msg->l2h;
	nsh->pdu_type = NS_PDUT_RESET;

	msgb_tvlv_put(msg, NS_IE_CAUSE, 1, &cause);
	msgb_tvlv_put(msg, NS_IE_VCI, 2, (uint8_t *) &nsvci);
	msgb_tvlv_put(msg, NS_IE_NSEI, 2, (uint8_t *) &nsei);

	return gprs_ns_tx(nsvc, msg);

}

/*! \brief Transmit a NS-STATUS on a given NSVC
 *  \param[in] nsvc NS-VC to be used for transmission
 *  \param[in] cause Numeric NS cause value
 *  \param[in] bvci BVCI to be reset within NSVC
 *  \param[in] orig_msg message causing the STATUS */
int gprs_ns_tx_status(struct gprs_nsvc *nsvc, uint8_t cause,
		      uint16_t bvci, struct msgb *orig_msg)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	struct gprs_ns_hdr *nsh;
	uint16_t nsvci = htons(nsvc->nsvci);

	log_set_context(GPRS_CTX_NSVC, nsvc);

	bvci = htons(bvci);

	if (!msg)
		return -ENOMEM;

	LOGP(DNS, LOGL_NOTICE, "NSEI=%u Tx NS STATUS (NSVCI=%u, cause=%s)\n",
		nsvc->nsei, nsvc->nsvci, gprs_ns_cause_str(cause));

	msg->l2h = msgb_put(msg, sizeof(*nsh));
	nsh = (struct gprs_ns_hdr *) msg->l2h;
	nsh->pdu_type = NS_PDUT_STATUS;

	msgb_tvlv_put(msg, NS_IE_CAUSE, 1, &cause);

	/* Section 9.2.7.1: Static conditions for NS-VCI */
	if (cause == NS_CAUSE_NSVC_BLOCKED ||
	    cause == NS_CAUSE_NSVC_UNKNOWN)
		msgb_tvlv_put(msg, NS_IE_VCI, 2, (uint8_t *)&nsvci);

	/* Section 9.2.7.2: Static conditions for NS PDU */
	switch (cause) {
	case NS_CAUSE_SEM_INCORR_PDU:
	case NS_CAUSE_PDU_INCOMP_PSTATE:
	case NS_CAUSE_PROTO_ERR_UNSPEC:
	case NS_CAUSE_INVAL_ESSENT_IE:
	case NS_CAUSE_MISSING_ESSENT_IE:
		msgb_tvlv_put(msg, NS_IE_PDU, msgb_l2len(orig_msg),
			      orig_msg->l2h);
		break;
	default:
		break;
	}

	/* Section 9.2.7.3: Static conditions for BVCI */
	if (cause == NS_CAUSE_BVCI_UNKNOWN)
		msgb_tvlv_put(msg, NS_IE_VCI, 2, (uint8_t *)&bvci);

	return gprs_ns_tx(nsvc, msg);
}

/*! \brief Transmit a NS-BLOCK on a tiven NS-VC
 *  \param[in] nsvc NS-VC on which the NS-BLOCK is to be transmitted
 *  \param[in] cause Numeric NS Cause value
 *  \returns 0 in case of success
 */
int gprs_ns_tx_block(struct gprs_nsvc *nsvc, uint8_t cause)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	struct gprs_ns_hdr *nsh;
	uint16_t nsvci = htons(nsvc->nsvci);

	log_set_context(GPRS_CTX_NSVC, nsvc);

	if (!msg)
		return -ENOMEM;

	LOGP(DNS, LOGL_INFO, "NSEI=%u Tx NS BLOCK (NSVCI=%u, cause=%s)\n",
		nsvc->nsei, nsvc->nsvci, gprs_ns_cause_str(cause));

	/* be conservative and mark it as blocked even now! */
	nsvc->state |= NSE_S_BLOCKED;
	rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_BLOCKED]);

	msg->l2h = msgb_put(msg, sizeof(*nsh));
	nsh = (struct gprs_ns_hdr *) msg->l2h;
	nsh->pdu_type = NS_PDUT_BLOCK;

	msgb_tvlv_put(msg, NS_IE_CAUSE, 1, &cause);
	msgb_tvlv_put(msg, NS_IE_VCI, 2, (uint8_t *) &nsvci);

	return gprs_ns_tx(nsvc, msg);
}

/*! \brief Transmit a NS-UNBLOCK on a given NS-VC
 *  \param[in] nsvc NS-VC on which the NS-UNBLOCK is to be transmitted
 *  \returns 0 in case of success
 */
int gprs_ns_tx_unblock(struct gprs_nsvc *nsvc)
{
	log_set_context(GPRS_CTX_NSVC, nsvc);
	LOGP(DNS, LOGL_INFO, "NSEI=%u Tx NS UNBLOCK (NSVCI=%u)\n",
		nsvc->nsei, nsvc->nsvci);

	return gprs_ns_tx_simple(nsvc, NS_PDUT_UNBLOCK);
}

/*! \brief Transmit a NS-ALIVE on a given NS-VC
 *  \param[in] nsvc NS-VC on which the NS-ALIVE is to be transmitted
 *  \returns 0 in case of success
 */
int gprs_ns_tx_alive(struct gprs_nsvc *nsvc)
{
	log_set_context(GPRS_CTX_NSVC, nsvc);
	LOGP(DNS, LOGL_DEBUG, "NSEI=%u Tx NS ALIVE (NSVCI=%u)\n",
		nsvc->nsei, nsvc->nsvci);

	return gprs_ns_tx_simple(nsvc, NS_PDUT_ALIVE);
}

/*! \brief Transmit a NS-ALIVE-ACK on a given NS-VC
 *  \param[in] nsvc NS-VC on which the NS-ALIVE-ACK is to be transmitted
 *  \returns 0 in case of success
 */
int gprs_ns_tx_alive_ack(struct gprs_nsvc *nsvc)
{
	log_set_context(GPRS_CTX_NSVC, nsvc);
	LOGP(DNS, LOGL_DEBUG, "NSEI=%u Tx NS ALIVE_ACK (NSVCI=%u)\n",
		nsvc->nsei, nsvc->nsvci);

	return gprs_ns_tx_simple(nsvc, NS_PDUT_ALIVE_ACK);
}

static const enum ns_timeout timer_mode_tout[_NSVC_TIMER_NR] = {
	[NSVC_TIMER_TNS_RESET]	= NS_TOUT_TNS_RESET,
	[NSVC_TIMER_TNS_ALIVE]	= NS_TOUT_TNS_ALIVE,
	[NSVC_TIMER_TNS_TEST]	= NS_TOUT_TNS_TEST,
};

static const struct value_string timer_mode_strs[] = {
	{ NSVC_TIMER_TNS_RESET, "tns-reset" },
	{ NSVC_TIMER_TNS_ALIVE, "tns-alive" },
	{ NSVC_TIMER_TNS_TEST, "tns-test" },
	{ 0, NULL }
};

static void nsvc_start_timer(struct gprs_nsvc *nsvc, enum nsvc_timer_mode mode)
{
	enum ns_timeout tout = timer_mode_tout[mode];
	unsigned int seconds = nsvc->nsi->timeout[tout];

	log_set_context(GPRS_CTX_NSVC, nsvc);
	DEBUGP(DNS, "NSEI=%u Starting timer in mode %s (%u seconds)\n",
		nsvc->nsei, get_value_string(timer_mode_strs, mode),
		seconds);
		
	if (osmo_timer_pending(&nsvc->timer))
		osmo_timer_del(&nsvc->timer);

	nsvc->timer_mode = mode;
	osmo_timer_schedule(&nsvc->timer, seconds, 0);
}

static void gprs_ns_timer_cb(void *data)
{
	struct gprs_nsvc *nsvc = data;
	enum ns_timeout tout = timer_mode_tout[nsvc->timer_mode];
	unsigned int seconds = nsvc->nsi->timeout[tout];

	log_set_context(GPRS_CTX_NSVC, nsvc);
	DEBUGP(DNS, "NSEI=%u Timer expired in mode %s (%u seconds)\n",
		nsvc->nsei, get_value_string(timer_mode_strs, nsvc->timer_mode),
		seconds);
		
	switch (nsvc->timer_mode) {
	case NSVC_TIMER_TNS_ALIVE:
		/* Tns-alive case: we expired without response ! */
		nsvc->alive_retries++;
		if (nsvc->alive_retries >
			nsvc->nsi->timeout[NS_TOUT_TNS_ALIVE_RETRIES]) {
			/* mark as dead and blocked */
			nsvc->state = NSE_S_BLOCKED;
			rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_BLOCKED]);
			rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_DEAD]);
			LOGP(DNS, LOGL_NOTICE,
				"NSEI=%u Tns-alive expired more then "
				"%u times, blocking NS-VC\n", nsvc->nsei,
				nsvc->nsi->timeout[NS_TOUT_TNS_ALIVE_RETRIES]);
			ns_osmo_signal_dispatch(nsvc, S_NS_ALIVE_EXP, 0);
			ns_osmo_signal_dispatch(nsvc, S_NS_BLOCK, NS_CAUSE_NSVC_BLOCKED);
			return;
		}
		/* Tns-test case: send NS-ALIVE PDU */
		gprs_ns_tx_alive(nsvc);
		/* start Tns-alive timer */
		nsvc_start_timer(nsvc, NSVC_TIMER_TNS_ALIVE);
		break;
	case NSVC_TIMER_TNS_TEST:
		/* Tns-test case: send NS-ALIVE PDU */
		gprs_ns_tx_alive(nsvc);
		/* start Tns-alive timer (transition into faster
		 * alive retransmissions) */
		nsvc->alive_retries = 0;
		nsvc_start_timer(nsvc, NSVC_TIMER_TNS_ALIVE);
		break;
	case NSVC_TIMER_TNS_RESET:
		/* Chapter 7.3: Re-send the RESET */
		gprs_ns_tx_reset(nsvc, NS_CAUSE_OM_INTERVENTION);
		/* Re-start Tns-reset timer */
		nsvc_start_timer(nsvc, NSVC_TIMER_TNS_RESET);
		break;
	case _NSVC_TIMER_NR:
		break;
	}
}

/* Section 9.2.6 */
static int gprs_ns_tx_reset_ack(struct gprs_nsvc *nsvc)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	struct gprs_ns_hdr *nsh;
	uint16_t nsvci, nsei;

	log_set_context(GPRS_CTX_NSVC, nsvc);
	if (!msg)
		return -ENOMEM;

	nsvci = htons(nsvc->nsvci);
	nsei = htons(nsvc->nsei);

	msg->l2h = msgb_put(msg, sizeof(*nsh));
	nsh = (struct gprs_ns_hdr *) msg->l2h;

	nsh->pdu_type = NS_PDUT_RESET_ACK;

	LOGP(DNS, LOGL_INFO, "NSEI=%u Tx NS RESET ACK (NSVCI=%u)\n",
		nsvc->nsei, nsvc->nsvci);

	msgb_tvlv_put(msg, NS_IE_VCI, 2, (uint8_t *)&nsvci);
	msgb_tvlv_put(msg, NS_IE_NSEI, 2, (uint8_t *)&nsei);

	return gprs_ns_tx(nsvc, msg);
}

/*! \brief High-level function for transmitting a NS-UNITDATA messsage
 *  \param[in] nsi NS-instance on which we shall transmit
 *  \param[in] msg struct msgb to be trasnmitted
 *
 * This function obtains the NS-VC by the msgb_nsei(msg) and then checks
 * if the NS-VC is ALIVEV and not BLOCKED.  After that, it adds a NS
 * header for the NS-UNITDATA message type and sends it off.
 *
 * Section 9.2.10: transmit side / NS-UNITDATA-REQUEST primitive 
 */
int gprs_ns_sendmsg(struct gprs_ns_inst *nsi, struct msgb *msg)
{
	struct gprs_nsvc *nsvc;
	struct gprs_ns_hdr *nsh;
	uint16_t bvci = msgb_bvci(msg);

	nsvc = gprs_nsvc_by_nsei(nsi, msgb_nsei(msg));
	if (!nsvc) {
		LOGP(DNS, LOGL_ERROR, "Unable to resolve NSEI %u "
			"to NS-VC!\n", msgb_nsei(msg));
		msgb_free(msg);
		return -EINVAL;
	}
	log_set_context(GPRS_CTX_NSVC, nsvc);

	if (!(nsvc->state & NSE_S_ALIVE)) {
		LOGP(DNS, LOGL_ERROR, "NSEI=%u is not alive, cannot send\n",
			nsvc->nsei);
		msgb_free(msg);
		return -EBUSY;
	}
	if (nsvc->state & NSE_S_BLOCKED) {
		LOGP(DNS, LOGL_ERROR, "NSEI=%u is blocked, cannot send\n",
			nsvc->nsei);
		msgb_free(msg);
		return -EBUSY;
	}

	msg->l2h = msgb_push(msg, sizeof(*nsh) + 3);
	nsh = (struct gprs_ns_hdr *) msg->l2h;
	if (!nsh) {
		LOGP(DNS, LOGL_ERROR, "Not enough headroom for NS header\n");
		msgb_free(msg);
		return -EIO;
	}

	nsh->pdu_type = NS_PDUT_UNITDATA;
	/* spare octet in data[0] */
	nsh->data[1] = bvci >> 8;
	nsh->data[2] = bvci & 0xff;

	return gprs_ns_tx(nsvc, msg);
}

/* Section 9.2.10: receive side */
static int gprs_ns_rx_unitdata(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *)msg->l2h;
	uint16_t bvci;

	if (nsvc->state & NSE_S_BLOCKED)
		return gprs_ns_tx_status(nsvc, NS_CAUSE_NSVC_BLOCKED,
					 0, msg);

	/* spare octet in data[0] */
	bvci = nsh->data[1] << 8 | nsh->data[2];
	msgb_bssgph(msg) = &nsh->data[3];
	msgb_bvci(msg) = bvci;

	/* call upper layer (BSSGP) */
	return nsvc->nsi->cb(GPRS_NS_EVT_UNIT_DATA, nsvc, msg, bvci);
}

/* Section 9.2.7 */
static int gprs_ns_rx_status(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
	struct tlv_parsed tp;
	uint8_t cause;
	int rc;

	LOGP(DNS, LOGL_NOTICE, "NSEI=%u Rx NS STATUS ", nsvc->nsei);

	rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data,
			msgb_l2len(msg) - sizeof(*nsh), 0, 0);
	if (rc < 0) {
		LOGPC(DNS, LOGL_NOTICE, "Error during TLV Parse\n");
		LOGP(DNS, LOGL_ERROR, "NSEI=%u Rx NS STATUS: "
			"Error during TLV Parse\n", nsvc->nsei);
		return rc;
	}

	if (!TLVP_PRESENT(&tp, NS_IE_CAUSE)) {
		LOGPC(DNS, LOGL_INFO, "missing cause IE\n");
		return -EINVAL;
	}

	cause = *TLVP_VAL(&tp, NS_IE_CAUSE);
	LOGPC(DNS, LOGL_NOTICE, "cause=%s\n", gprs_ns_cause_str(cause));

	return 0;
}

/* Section 7.3 */
static int gprs_ns_rx_reset(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
	struct tlv_parsed tp;
	uint8_t *cause;
	uint16_t *nsvci, *nsei;
	int rc;

	rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data,
			msgb_l2len(msg) - sizeof(*nsh), 0, 0);
	if (rc < 0) {
		LOGP(DNS, LOGL_ERROR, "NSEI=%u Rx NS RESET "
			"Error during TLV Parse\n", nsvc->nsei);
		return rc;
	}

	if (!TLVP_PRESENT(&tp, NS_IE_CAUSE) ||
	    !TLVP_PRESENT(&tp, NS_IE_VCI) ||
	    !TLVP_PRESENT(&tp, NS_IE_NSEI)) {
		LOGP(DNS, LOGL_ERROR, "NS RESET Missing mandatory IE\n");
		gprs_ns_tx_status(nsvc, NS_CAUSE_MISSING_ESSENT_IE, 0, msg);
		return -EINVAL;
	}

	cause = (uint8_t *) TLVP_VAL(&tp, NS_IE_CAUSE);
	nsvci = (uint16_t *) TLVP_VAL(&tp, NS_IE_VCI);
	nsei = (uint16_t *) TLVP_VAL(&tp, NS_IE_NSEI);

	LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS RESET (NSVCI=%u, cause=%s)\n",
		nsvc->nsvci, nsvc->nsei, gprs_ns_cause_str(*cause));

	/* Mark NS-VC as blocked and alive */
	nsvc->state = NSE_S_BLOCKED | NSE_S_ALIVE;

	nsvc->nsei = ntohs(*nsei);
	nsvc->nsvci = ntohs(*nsvci);

	/* start the test procedure */
	gprs_ns_tx_simple(nsvc, NS_PDUT_ALIVE);
	nsvc_start_timer(nsvc, NSVC_TIMER_TNS_TEST);

	/* inform interested parties about the fact that this NSVC
	 * has received RESET */
	ns_osmo_signal_dispatch(nsvc, S_NS_RESET, *cause);

	return gprs_ns_tx_reset_ack(nsvc);
}

static int gprs_ns_rx_block(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
	struct tlv_parsed tp;
	uint8_t *cause;
	int rc;

	LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS BLOCK\n", nsvc->nsei);

	nsvc->state |= NSE_S_BLOCKED;

	rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data,
			msgb_l2len(msg) - sizeof(*nsh), 0, 0);
	if (rc < 0) {
		LOGP(DNS, LOGL_ERROR, "NSEI=%u Rx NS BLOCK "
			"Error during TLV Parse\n", nsvc->nsei);
		return rc;
	}

	if (!TLVP_PRESENT(&tp, NS_IE_CAUSE) ||
	    !TLVP_PRESENT(&tp, NS_IE_VCI)) {
		LOGP(DNS, LOGL_ERROR, "NS RESET Missing mandatory IE\n");
		gprs_ns_tx_status(nsvc, NS_CAUSE_MISSING_ESSENT_IE, 0, msg);
		return -EINVAL;
	}

	cause = (uint8_t *) TLVP_VAL(&tp, NS_IE_CAUSE);
	//nsvci = (uint16_t *) TLVP_VAL(&tp, NS_IE_VCI);

	ns_osmo_signal_dispatch(nsvc, S_NS_BLOCK, *cause);
	rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_BLOCKED]);

	return gprs_ns_tx_simple(nsvc, NS_PDUT_BLOCK_ACK);
}

/*! \brief Receive incoming NS message from underlying transport layer
 *  \param nsi NS instance to which the data belongs
 *  \param[in] msg message buffer containing newly-received data
 *  \param[in] saddr socketaddr from which data was received
 *  \param[in] ll link-layer type in which data was received
 *  \returns 0 in case of success, < 0 in case of error
 *
 * This is the main entry point int othe NS imlementation where frames
 * from the underlying transport (normally UDP) enter.
 */
int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
		   struct sockaddr_in *saddr, enum gprs_ns_ll ll)
{
	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
	struct gprs_nsvc *nsvc;
	int rc = 0;

	/* look up the NSVC based on source address */
	nsvc = nsvc_by_rem_addr(nsi, saddr);
	if (!nsvc) {
		struct tlv_parsed tp;
		uint16_t nsei;
		if (nsh->pdu_type == NS_PDUT_STATUS) {
			LOGP(DNS, LOGL_INFO, "Ignoring NS STATUS from %s:%u "
			     "for non-existing NS-VC\n",
			     inet_ntoa(saddr->sin_addr), ntohs(saddr->sin_port));
			return 0;
		}
		/* Only the RESET procedure creates a new NSVC */
		if (nsh->pdu_type != NS_PDUT_RESET) {
			/* Since we have no NSVC, we have to use a fake */
			nsvc = nsi->unknown_nsvc;
			log_set_context(GPRS_CTX_NSVC, nsvc);
			LOGP(DNS, LOGL_INFO, "Rejecting NS PDU type 0x%0x "
				"from %s:%u for non-existing NS-VC\n",
				nsh->pdu_type, inet_ntoa(saddr->sin_addr),
				ntohs(saddr->sin_port));
			nsvc->nsvci = nsvc->nsei = 0xfffe;
			nsvc->ip.bts_addr = *saddr;
			nsvc->state = NSE_S_ALIVE;
			nsvc->ll = ll;
#if 0
			return gprs_ns_tx_reset(nsvc, NS_CAUSE_PDU_INCOMP_PSTATE);
#else
			return gprs_ns_tx_status(nsvc,
						NS_CAUSE_PDU_INCOMP_PSTATE, 0,
						msg);
#endif
		}
		rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data,
				msgb_l2len(msg) - sizeof(*nsh), 0, 0);
		if (rc < 0) {
			LOGP(DNS, LOGL_ERROR, "Rx NS RESET Error %d during "
				"TLV Parse\n", rc);
			return rc;
		}
		if (!TLVP_PRESENT(&tp, NS_IE_CAUSE) ||
		    !TLVP_PRESENT(&tp, NS_IE_VCI) ||
		    !TLVP_PRESENT(&tp, NS_IE_NSEI)) {
			LOGP(DNS, LOGL_ERROR, "NS RESET Missing mandatory IE\n");
			gprs_ns_tx_status(nsvc, NS_CAUSE_MISSING_ESSENT_IE, 0,
					  msg);
			return -EINVAL;
		}
		nsei = ntohs(*(uint16_t *)TLVP_VAL(&tp, NS_IE_NSEI));
		/* Check if we already know this NSEI, the remote end might
		 * simply have changed addresses, or it is a SGSN */
		nsvc = gprs_nsvc_by_nsei(nsi, nsei);
		if (!nsvc) {
			nsvc = gprs_nsvc_create(nsi, 0xffff);
			nsvc->ll = ll;
			log_set_context(GPRS_CTX_NSVC, nsvc);
			LOGP(DNS, LOGL_INFO, "Creating NS-VC for BSS at %s:%u\n",
				inet_ntoa(saddr->sin_addr), ntohs(saddr->sin_port));
		}
		/* Update the remote peer IP address/port */
		nsvc->ip.bts_addr = *saddr;
	} else
		msgb_nsei(msg) = nsvc->nsei;

	log_set_context(GPRS_CTX_NSVC, nsvc);

	/* Increment number of Incoming bytes */
	rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_PKTS_IN]);
	rate_ctr_add(&nsvc->ctrg->ctr[NS_CTR_BYTES_IN], msgb_l2len(msg));

	switch (nsh->pdu_type) {
	case NS_PDUT_ALIVE:
		/* If we're dead and blocked and suddenly receive a
		 * NS-ALIVE out of the blue, we might have been re-started
		 * and should send a NS-RESET to make sure everything recovers
		 * fine. */
		if (nsvc->state == NSE_S_BLOCKED)
			rc = gprs_ns_tx_reset(nsvc, NS_CAUSE_PDU_INCOMP_PSTATE);
		else
			rc = gprs_ns_tx_alive_ack(nsvc);
		break;
	case NS_PDUT_ALIVE_ACK:
		/* stop Tns-alive and start Tns-test */
		nsvc_start_timer(nsvc, NSVC_TIMER_TNS_TEST);
		if (nsvc->remote_end_is_sgsn) {
			/* FIXME: this should be one level higher */
			if (nsvc->state & NSE_S_BLOCKED)
				rc = gprs_ns_tx_unblock(nsvc);
		}
		break;
	case NS_PDUT_UNITDATA:
		/* actual user data */
		rc = gprs_ns_rx_unitdata(nsvc, msg);
		break;
	case NS_PDUT_STATUS:
		rc = gprs_ns_rx_status(nsvc, msg);
		break;
	case NS_PDUT_RESET:
		rc = gprs_ns_rx_reset(nsvc, msg);
		break;
	case NS_PDUT_RESET_ACK:
		LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS RESET ACK\n", nsvc->nsei);
		/* mark NS-VC as blocked + active */
		nsvc->state = NSE_S_BLOCKED | NSE_S_ALIVE;
		nsvc->remote_state = NSE_S_BLOCKED | NSE_S_ALIVE;
		rate_ctr_inc(&nsvc->ctrg->ctr[NS_CTR_BLOCKED]);
		if (nsvc->persistent || nsvc->remote_end_is_sgsn) {
			/* stop RESET timer */
			osmo_timer_del(&nsvc->timer);
		}
		/* Initiate TEST proc.: Send ALIVE and start timer */
		rc = gprs_ns_tx_simple(nsvc, NS_PDUT_ALIVE);
		nsvc_start_timer(nsvc, NSVC_TIMER_TNS_TEST);
		break;
	case NS_PDUT_UNBLOCK:
		/* Section 7.2: unblocking procedure */
		LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS UNBLOCK\n", nsvc->nsei);
		nsvc->state &= ~NSE_S_BLOCKED;
		ns_osmo_signal_dispatch(nsvc, S_NS_UNBLOCK, 0);
		rc = gprs_ns_tx_simple(nsvc, NS_PDUT_UNBLOCK_ACK);
		break;
	case NS_PDUT_UNBLOCK_ACK:
		LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS UNBLOCK ACK\n", nsvc->nsei);
		/* mark NS-VC as unblocked + active */
		nsvc->state = NSE_S_ALIVE;
		nsvc->remote_state = NSE_S_ALIVE;
		ns_osmo_signal_dispatch(nsvc, S_NS_UNBLOCK, 0);
		break;
	case NS_PDUT_BLOCK:
		rc = gprs_ns_rx_block(nsvc, msg);
		break;
	case NS_PDUT_BLOCK_ACK:
		LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS BLOCK ACK\n", nsvc->nsei);
		/* mark remote NS-VC as blocked + active */
		nsvc->remote_state = NSE_S_BLOCKED | NSE_S_ALIVE;
		break;
	default:
		LOGP(DNS, LOGL_NOTICE, "NSEI=%u Rx Unknown NS PDU type 0x%02x\n",
			nsvc->nsei, nsh->pdu_type);
		rc = -EINVAL;
		break;
	}
	return rc;
}

/*! \brief Create a new GPRS NS instance
 *  \param[in] cb Call-back function for incoming BSSGP data
 *  \returns dynamically allocated gprs_ns_inst
 */
struct gprs_ns_inst *gprs_ns_instantiate(gprs_ns_cb_t *cb, void *ctx)
{
	struct gprs_ns_inst *nsi = talloc_zero(ctx, struct gprs_ns_inst);

	nsi->cb = cb;
	INIT_LLIST_HEAD(&nsi->gprs_nsvcs);
	nsi->timeout[NS_TOUT_TNS_BLOCK] = 3;
	nsi->timeout[NS_TOUT_TNS_BLOCK_RETRIES] = 3;
	nsi->timeout[NS_TOUT_TNS_RESET] = 3;
	nsi->timeout[NS_TOUT_TNS_RESET_RETRIES] = 3;
	nsi->timeout[NS_TOUT_TNS_TEST] = 30;
	nsi->timeout[NS_TOUT_TNS_ALIVE] = 3;
	nsi->timeout[NS_TOUT_TNS_ALIVE_RETRIES] = 10;

	/* Create the dummy NSVC that we use for sending
	 * messages to non-existant/unknown NS-VC's */
	nsi->unknown_nsvc = gprs_nsvc_create(nsi, 0xfffe);
	llist_del(&nsi->unknown_nsvc->list);

	return nsi;
}

/*! \brief Destroy an entire NS instance
 *  \param nsi gprs_ns_inst that is to be destroyed
 *
 *  This function SHOULD release all resources associated with the
 *  NS-instance but is actually not completely implemented!
 */
void gprs_ns_destroy(struct gprs_ns_inst *nsi)
{
	/* FIXME: clear all timers */

	/* recursively free the NSI and all its NSVCs */
	talloc_free(nsi);
}


/* NS-over-IP code, according to 3GPP TS 48.016 Chapter 6.2
 * We don't support Size Procedure, Configuration Procedure, ChangeWeight Procedure */

/* Read a single NS-over-IP message */
static struct msgb *read_nsip_msg(struct osmo_fd *bfd, int *error,
				  struct sockaddr_in *saddr)
{
	struct msgb *msg = gprs_ns_msgb_alloc();
	int ret = 0;
	socklen_t saddr_len = sizeof(*saddr);

	if (!msg) {
		*error = -ENOMEM;
		return NULL;
	}

	ret = recvfrom(bfd->fd, msg->data, NS_ALLOC_SIZE - NS_ALLOC_HEADROOM, 0,
			(struct sockaddr *)saddr, &saddr_len);
	if (ret < 0) {
		LOGP(DNS, LOGL_ERROR, "recv error %s during NSIP recv\n",
			strerror(errno));
		msgb_free(msg);
		*error = ret;
		return NULL;
	} else if (ret == 0) {
		msgb_free(msg);
		*error = ret;
		return NULL;
	}

	msg->l2h = msg->data;
	msgb_put(msg, ret);

	return msg;
}

static int handle_nsip_read(struct osmo_fd *bfd)
{
	int error;
	struct sockaddr_in saddr;
	struct gprs_ns_inst *nsi = bfd->data;
	struct msgb *msg = read_nsip_msg(bfd, &error, &saddr);

	if (!msg)
		return error;

	error = gprs_ns_rcvmsg(nsi, msg, &saddr, GPRS_NS_LL_UDP);

	msgb_free(msg);

	return error;
}

static int handle_nsip_write(struct osmo_fd *bfd)
{
	/* FIXME: actually send the data here instead of nsip_sendmsg() */
	return -EIO;
}

static int nsip_sendmsg(struct gprs_nsvc *nsvc, struct msgb *msg)
{
	int rc;
	struct gprs_ns_inst *nsi = nsvc->nsi;
	struct sockaddr_in *daddr = &nsvc->ip.bts_addr;

	rc = sendto(nsi->nsip.fd.fd, msg->data, msg->len, 0,
		  (struct sockaddr *)daddr, sizeof(*daddr));

	msgb_free(msg);

	return rc;
}

/* UDP Port 23000 carries the LLC-in-BSSGP-in-NS protocol stack */
static int nsip_fd_cb(struct osmo_fd *bfd, unsigned int what)
{
	int rc = 0;

	if (what & BSC_FD_READ)
		rc = handle_nsip_read(bfd);
	if (what & BSC_FD_WRITE)
		rc = handle_nsip_write(bfd);

	return rc;
}

/*! \brief Create a listening socket for GPRS NS/UDP/IP
 *  \param[in] nsi NS protocol instance to listen
 *  \returns >=0 (fd) in case of success, negative in case of error
 *
 *  A call to this function will create a UDP socket bound to the port
 *  number and IP address specified in the NS protocol instance. The
 *  file descriptor of the socket will be stored in nsi->nsip.fd.
 */
int gprs_ns_nsip_listen(struct gprs_ns_inst *nsi)
{
	struct in_addr in;
	int ret;

	in.s_addr = htonl(nsi->nsip.local_ip);

	nsi->nsip.fd.cb = nsip_fd_cb;
	nsi->nsip.fd.data = nsi;
	ret = osmo_sock_init_ofd(&nsi->nsip.fd, AF_INET, SOCK_DGRAM,
				 IPPROTO_UDP, inet_ntoa(in),
				 nsi->nsip.local_port, OSMO_SOCK_F_BIND);
	if (ret < 0)
		return ret;


	return ret;
}

/*! \brief Initiate a RESET procedure
 *  \param[in] nsvc NS-VC in which to start the procedure
 *  \param[in] cause Numeric NS cause value
 *
 * This is a high-level function initiating a NS-RESET procedure. It
 * will not only send a NS-RESET, but also set the state to BLOCKED and
 * start the Tns-reset timer.
 */
void gprs_nsvc_reset(struct gprs_nsvc *nsvc, uint8_t cause)
{
	LOGP(DNS, LOGL_INFO, "NSEI=%u RESET procedure based on API request\n",
		nsvc->nsei);

	/* Mark NS-VC locally as blocked and dead */
	nsvc->state = NSE_S_BLOCKED;
	/* Send NS-RESET PDU */
	if (gprs_ns_tx_reset(nsvc, cause) < 0) {
		LOGP(DNS, LOGL_ERROR, "NSEI=%u, error resetting NS-VC\n",
			nsvc->nsei);
	}
	/* Start Tns-reset */
	nsvc_start_timer(nsvc, NSVC_TIMER_TNS_RESET);
}

/*! \brief Establish a NS connection (from the BSS) to the SGSN
 *  \param nsi NS-instance
 *  \param[in] dest Destination IP/Port
 *  \param[in] nsei NSEI of the to-be-established NS-VC
 *  \param[in] nsvci NSVCI of the to-be-established NS-VC
 *  \returns struct gprs_nsvc representing the new NS-VC
 *
 * This function will establish a single NS/UDP/IP connection in uplink
 * (BSS to SGSN) direction.
 */
struct gprs_nsvc *gprs_ns_nsip_connect(struct gprs_ns_inst *nsi,
				struct sockaddr_in *dest, uint16_t nsei,
				uint16_t nsvci)
{
	struct gprs_nsvc *nsvc;

	nsvc = nsvc_by_rem_addr(nsi, dest);
	if (!nsvc)
		nsvc = gprs_nsvc_create(nsi, nsvci);
	nsvc->ip.bts_addr = *dest;
	nsvc->nsei = nsei;
	nsvc->nsvci = nsvci;
	nsvc->remote_end_is_sgsn = 1;

	gprs_nsvc_reset(nsvc, NS_CAUSE_OM_INTERVENTION);
	return nsvc;
}

void gprs_ns_set_log_ss(int ss)
{
	DNS = ss;
}

/*! }@ */