summaryrefslogtreecommitdiffstats
path: root/epan/dissectors/packet-gsm_bsslap.c
blob: 22d0cd34f9815978b7fb85a501b524d9d68318cd (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
/* packet-gsm_bsslap.c
 * Routines for Location Services (LCS) Serving Mobile Location Centre - Base Station System (SMLC-BSS) dissection
 * Copyright 2008, Anders Broman <anders.broman[at]ericsson.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * References: 3GPP TS 48.071 version 7.2.0 Release 7
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/tfs.h>
#include <wsutil/array.h>

#include "packet-gsm_a_common.h"

void proto_reg_handoff_gsm_bsslap(void);
void proto_register_gsm_bsslap(void);

static dissector_handle_t bsslap_rrlp_handle;

/* Initialize the protocol and registered fields */
static int proto_gsm_bsslap;
static int hf_gsm_bsslap_msg_type;
int hf_gsm_a_bsslap_elem_id;
static int hf_gsm_bsslap_ta;
static int hf_gsm_bsslap_timer_value;
static int hf_gsm_bsslap_ms_pow;
static int hf_gsm_bsslap_cause;
static int hf_gsm_bsslap_rrlp_flg;
static int hf_gsm_bsslap_tfi;
static int hf_gsm_bsslap_poll_rep;
static int hf_gsm_bsslap_lac;
static int hf_gsm_bsslap_cell_id_disc;
static int hf_gsm_bsslap_encryption_key;

/* Initialize the subtree pointers */
static int ett_gsm_bsslap;
static int ett_bsslap_cell_list;

static expert_field ei_gsm_bsslap_missing_mandatory_element;
static expert_field ei_gsm_bsslap_not_decoded_yet;

/* Table 5.1: Element Identifier codes */
#define BSSLAP_PARAM_TIMING_ADVANCE                  0x01
#define BSSLAP_PARAM_RESERVED_01                     0x08
#define BSSLAP_PARAM_CELL_IDENTITY                   0x09
#define BSSLAP_PARAM_RESERVED_02                     0x0A
#define BSSLAP_PARAM_RESERVED_03                     0x0B
#define BSSLAP_PARAM_RESERVED_04                     0x0C
#define BSSLAP_PARAM_CHANNEL_DESCRIPTION             0x10
#define BSSLAP_PARAM_RESERVED_05                     0x11
#define BSSLAP_PARAM_RESERVED_06                     0x12
#define BSSLAP_PARAM_RESERVED_07                     0x13
#define BSSLAP_PARAM_MEASUREMENT_REPORT              0x14
#define BSSLAP_PARAM_RESERVED_08                     0x15
#define BSSLAP_PARAM_CAUSE                           0x18
#define BSSLAP_PARAM_RRLP_FLAG                       0x19
#define BSSLAP_PARAM_RRLP_IE                         0x1B
#define BSSLAP_PARAM_CELL_IDENTITY_LIST              0x1C
#define BSSLAP_PARAM_ENHANCED_MEASUREMENT_REPORT     0x1D
#define BSSLAP_PARAM_LOCATION_AREA_CODE              0x1E
#define BSSLAP_PARAM_FREQUENCY_LIST                  0x21
#define BSSLAP_PARAM_MS_POWER                        0x22
#define BSSLAP_PARAM_DELTA_TIMER                     0x23
#define BSSLAP_PARAM_SERVING_CELL_IDENTIFIER         0x24
#define BSSLAP_PARAM_ENCRYPTION_KEY                  0x25
#define BSSLAP_PARAM_CIPHER_MODE_SETTING             0x26
#define BSSLAP_PARAM_CHANNEL_MODE                    0x27
#define BSSLAP_PARAM_MULTIRATE_CONFIGURATION         0x28
#define BSSLAP_PARAM_POLLING_REPETITION              0x29
#define BSSLAP_PARAM_PACKET_CHANNEL_DESCRIPTION      0x2A
#define BSSLAP_PARAM_TLLI                            0x2B
#define BSSLAP_PARAM_TFI                             0x2C
#define BSSLAP_PARAM_STARTING_TIME                   0x2D

static const value_string gsm_bsslap_elem_strings[] = {
    {  DE_BLAP_RES1,         "Reserved" },
    {  DE_BLAP_TA,           "Timing Advance" },
    {  DE_BLAP_RES3,         "Reserved" },          /* (note) */
    {  DE_BLAP_RES4,         "Cell Identity" },
    {  DE_BLAP_RES5,         "Reserved" },          /* (note) */
    {  DE_BLAP_RES6,         "Reserved" },          /* (note) */
    {  DE_BLAP_RES7,         "Reserved" },          /* (note) */
    {  DE_BLAP_CH_DESC,      "Channel Description" },
    {  DE_BLAP_RES9,         "Reserved" },          /* (note) */
    {  DE_BLAP_RES10,        "Reserved" },          /* (note) */
    {  DE_BLAP_RES11,        "Reserved" },          /* (note) */
    {  DE_BLAP_MEAS_REP,     "Measurement Report" },
    {  DE_BLAP_RES13,        "Reserved" },          /* (note) */
    {  DE_BLAP_CAUSE,        "Cause" },
    {  DE_BLAP_RRLP_FLG,     "RRLP Flag" },
    {  DE_BLAP_RRLP_IE,      "RRLP IE" },
    {  DE_BLAP_CELL_ID_LIST, "Cell Identity List" },
    {  DE_BLAP_ENH_MEAS_REP, "Enhanced Measurement Report" },
    {  DE_BLAP_LAC,          "Location Area Code" },
    {  DE_BLAP_FREQ_LIST,    "Frequency List" },
    {  DE_BLAP_MS_POW,       "MS Power" },
    {  DE_BLAP_DELTA_TIME,   "Delta Timer" },
    {  DE_BLAP_SERV_CELL_ID, "Serving Cell Identifier" },
    {  DE_BLAP_ENC_KEY,      "Encryption Key (Kc)" },
    {  DE_BLAP_CIP_M_SET,    "Cipher Mode Setting" },
    {  DE_BLAP_CH_MODE,      "Channel Mode" },
    {  DE_BLAP_POLL_REP,     "Polling Repetition" },
    {  DE_BLAP_PKT_CH_DESC,  "Packet Channel Description" },
    {  DE_BLAP_TLLI,         "TLLI" },
    {  DE_BLAP_TFI,          "TFI" },
    {  DE_BLAP_START_TIME,   "Starting Time" },
    { 0,        NULL },
};
value_string_ext gsm_bsslap_elem_strings_ext = VALUE_STRING_EXT_INIT(gsm_bsslap_elem_strings);

/*
 *  NOTE: These values of the codepoints shall not be used as they were used in an earlier version of the
 *  protocol.
 *  All unassigned codes are spare.
 */


#define BSSLAP_TA_REQUEST    1
#define BSSLAP_TA_RESPONSE   2
#define BSSLAP_REJECT       10
#define BSSLAP_RESET        11
#define BSSLAP_ABORT        12
#define BSSLAP_TA_LAYER3    13
#define BSSLAP_MS_POS_CMD   15
#define BSSLAP_MS_POS_RES   16
#define BSSLAP_U_TDOA_REQ   17
#define BSSLAP_U_TDOA_RES   18

/* Table 5.1.1: Message Type codes */
static const value_string gsm_a_bsslap_msg_strings[] = {
    {  0x00,               "Reserved" },
    {  BSSLAP_TA_REQUEST,  "TA REQUEST" },
    {  BSSLAP_TA_RESPONSE, "TA RESPONSE" },
    {  0x04,               "Reserved" },
    {  0x05,               "Reserved" },
    {  BSSLAP_REJECT,      "REJECT" },
    {  BSSLAP_RESET,       "RESET" },
    {  BSSLAP_ABORT,       "ABORT" },
    {  BSSLAP_TA_LAYER3,   "TA LAYER3" },
    {  BSSLAP_MS_POS_CMD,  "MS Position Command" },
    {  BSSLAP_MS_POS_RES,  "MS Position Response" },
    {  BSSLAP_U_TDOA_REQ,  "U-TDOA Request" },
    {  BSSLAP_U_TDOA_RES,  "U-TDOA Response" },
    { 0,            NULL }
};

#define NUM_GSM_BSSLAP_ELEM array_length(gsm_bsslap_elem_strings)
int ett_gsm_bsslap_elem[NUM_GSM_BSSLAP_ELEM];

/*
 * 5.2 Timing Advance IE
 */
static uint16_t
de_ta(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_ta, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
/*
 * 5.12 Measurement Report IE
 */
#if 0
static uint16_t
de_meas_rep(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_expert(tree, pinfo, &ei_gsm_bsslap_not_decoded_yet, tvb, curr_offset, len);


    return len;
}
#endif
/*
 * 5.14 Cause IE
 */
static const value_string gsm_bsslap_cause_vals[] = {
    { 0x00, "Congestion" },
    { 0x01, "Channel Mode not supported" },
    { 0x02, "Positioning procedure not supported" },
    { 0x03, "Failure for other radio related events" },
    { 0x04, "Intra-BSS handover" },
    { 0x05, "Supervision Timer Expired" },
    { 0x06, "Inter-BSS handover" },
    { 0x07, "Loss of signalling connection to MS" },
    { 0x08, "Incorrect serving cell identity" },
    { 0x09, "BSSAP-LE Segmentation error" },
    { 0,    NULL }
};

static uint16_t
de_bsslap_cause(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_cause, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
/*
 * 5.15 RRLP Flag IE
 */
static const true_false_string gsm_bsslap_rrlp_flg_vals = {
    "Not a Positioning Command or final response." ,
    "Position Command (SMLC to BSC) or final response (BSC to SMLC)"
};
static uint16_t
de_rrlp_flg(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_rrlp_flg, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
static uint16_t
de_rrlp_ie(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;
    tvbuff_t *rrlp_tvb;
    uint16_t length;

    length = tvb_get_ntohs(tvb, offset);

    curr_offset = offset + 2;
    if (length > 0)
    {
        rrlp_tvb = tvb_new_subset_length(tvb, curr_offset, length);
        if (bsslap_rrlp_handle)
            call_dissector(bsslap_rrlp_handle, rrlp_tvb, pinfo, tree);
    }

    curr_offset += length;
    return curr_offset - offset;
}
/*
 * 5.17 Cell Identity List IE
 */
/*
 * The Cell identification discriminator i is coded as follows:
 */
static const value_string gsm_a_bsslap_cell_id_disc_vals[] = {
    {  0x0, "The whole Cell Global Identification, CGI, is used to identify the 2G cells" },
    {  0x1, "Location Area Code, LAC, and Cell Identify, CI, are used to identify the 2G cells" },
    {  0x2, "3G Cell identification container 1" },
    {  0x3, "3G Cell identification container 2" },
    { 0,            NULL }
};



static uint16_t
de_cell_id_list(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;
    uint8_t consumed;
    uint8_t cell_id_disc;
    uint8_t num_cells;
    proto_item  *item = NULL;
    proto_tree  *subtree = NULL;

    curr_offset = offset;
    cell_id_disc = tvb_get_uint8(tvb,curr_offset);
    num_cells = 0;

    while(len>0){
        num_cells++;
        consumed = 0;
        subtree = proto_tree_add_subtree_format(tree, tvb, curr_offset, -1, ett_bsslap_cell_list, &item, "Cell %u", num_cells);

        if (add_string)
            add_string[0] = '\0';
        proto_tree_add_item(subtree, hf_gsm_bsslap_cell_id_disc, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
        curr_offset++;
        len--;
        switch(cell_id_disc){
            case 0:
                /* The whole Cell Global Identification, CGI, is used to identify the 2G cells. */
                consumed+= be_cell_id_aux(tvb, subtree, pinfo, curr_offset, len, NULL, 0, 0);
                break;
            case 1:
                /* Location Area Code, LAC, and Cell Identify, CI, are used to identify the 2G cells. */
                consumed+= be_cell_id_aux(tvb, subtree, pinfo, curr_offset, len, NULL, 0, 1);
                break;
            case 2:
                /* 3G Cell identification container 1 */
                /* fall trough */
            case 3:
                /* 3G Cell identification container 2 */
                /* fall trough */
            default:
                proto_tree_add_expert(subtree, pinfo, &ei_gsm_bsslap_not_decoded_yet, tvb, curr_offset, len);
                consumed = len;
                break;
        }
        curr_offset += consumed;
        len-=consumed;
        /* length is "cell id" + discriminator */
        proto_item_set_len(item, consumed+1);
    }


    return curr_offset - offset;
}
/*
 * 5.18 Enhanced Measurement Report IE
 * The Enhanced Measurement Results field is encoded as the contents of the
 * ENHANCED MEASUREMENT REPORT message in 3GPP TS 44.018 (excluding the fields:
 * "RR short PD", "Message type" and "Short layer 2 header")...
 */
static uint16_t
de_enh_meas_rep(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_expert(tree, pinfo, &ei_gsm_bsslap_not_decoded_yet, tvb, curr_offset, len);


    return len;
}
/*
 * 5.19 Location Area Code IE
 */
static uint16_t
de_lac(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_lac, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
/*
 * 5.21 MS Power IE
 */
static uint16_t
de_ms_pow(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_ms_pow, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}

/*
 * 5.22 Delta Timer IE
 */
static uint16_t
de_delta_time(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_timer_value, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
/*
 * 5.23 Serving Cell Identifier IE
 * The Serving Cell Identifier IE is encoded as in 3GPP TS 48.008 (excluding IEI and length field).
 */
/*
 * 5.24 Encryption Key
 */
static uint16_t
de_blap_enc_key(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_encryption_key, tvb, curr_offset, 8, ENC_NA);
    curr_offset = curr_offset + 8;

    return curr_offset - offset;
}
/*
 * 5.25 Cipher Mode Setting IE
 * The Cipher Mode Setting information element is coded as defined in TS 44.018 (excluding IEI).
 */
/*
 * 5.26 Channel Mode IE
 * The Channel Mode information element is coded as defined in TS 44.018 (excluding IEI).
 */
/*
 * 5.27 MultiRate Configuration IE
 * The MultiRate Configuration information element is coded as defined in TS 44.018 (excluding IEI).
 */
/*
 * 5.28 Polling Repetition IE
 */
static uint16_t
de_poll_rep(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_poll_rep, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}
/*
 * 5.29 Packet Channel Description IE
 * CSN.1 binary representation of the channel parameters as
 * described in TS 44.018 (CCCH) or TS 44.060 (PCCCH) plus
 * padding bits (binary 0) as required to achieve 4 complete octets
 */
static uint16_t
de_pkt_ch_desc(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_expert(tree, pinfo, &ei_gsm_bsslap_not_decoded_yet, tvb, curr_offset, len);


    return len;
}
/*
 * 5.31 TFI IE
 * The TFI information element is coded as defined in TS 44.060 (excluding IEI).
 * 44.060:
 * UPLINK_TFI (5 bit field)
 * The Temporary Flow Identity field identifies an uplink Temporary Block Flow (TBF).
 * This field is encoded as a binary number. Range 0 to 31
 */
static uint16_t
de_tfi(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;
    proto_tree_add_item(tree, hf_gsm_bsslap_tfi, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset++;

    return curr_offset - offset;
}

/*
This enum has been moved to packet-gsm_a_common to
make it possible to use element dissecton from this dissector
in other dissectors.
It is left here as a comment for easier reference.

Note this enum must be of the same size as the element decoding list

typedef enum
{
    /. BSS LAP Elements 5 ./
    DE_BLAP_RES1,           /. Reserved ./
    DE_BLAP_TA,             /. Timing Advance ./
    DE_BLAP_RES3,           /. Reserved ./          /. (note) ./
    DE_BLAP_RES4,           /. Cell Identity ./
    DE_BLAP_RES5,           /. Reserved ./          /. (note) ./
    DE_BLAP_RES6,           /. Reserved ./          /. (note) ./
    DE_BLAP_RES7,           /. Reserved ./          /. (note) ./
    DE_BLAP_CH_DESC,        /. Channel Description ./
    DE_BLAP_RES9,           /. Reserved ./          /. (note) ./
    DE_BLAP_RES10,          /. Reserved ./          /. (note) ./
    DE_BLAP_RES11,          /. Reserved ./          /. (note) ./
    DE_BLAP_MEAS_REP,       /. Measurement Report ./
    DE_BLAP_RES13,          /. Reserved ./          /. (note) ./
    DE_BLAP_CAUSE,          /. Cause ./
    DE_BLAP_RRLP_FLG,       /. RRLP Flag ./
    DE_BLAP_RRLP_IE,        /. RRLP IE ./
    DE_BLAP_CELL_ID_LIST,   /. Cell Identity List ./
    DE_BLAP_ENH_MEAS_REP,   /. Enhanced Measurement Report ./
    DE_BLAP_LAC,            /. Location Area Code ./
    DE_BLAP_FREQ_LIST,      /. Frequency List ./
    DE_BLAP_MS_POW,         /. MS Power ./
    DE_BLAP_DELTA_TIME,     /. Delta Timer ./
    DE_BLAP_SERV_CELL_ID,   /. Serving Cell Identifier ./
    DE_BLAP_ENC_KEY,        /. Encryption Key (Kc) ./
    DE_BLAP_CIP_M_SET,      /. Cipher Mode Setting ./
    DE_BLAP_CH_MODE,        /. Channel Mode ./
    DE_BLAP_POLL_REP,       /. Polling Repetition ./
    DE_BLAP_PKT_CH_DESC,    /. Packet Channel Description ./
    DE_BLAP_TLLI,           /. TLLI ./
    DE_BLAP_TFI,            /. TFI ./
    DE_BLAP_START_TIME,     /. Starting Time ./
    BSSLAP_NONE             /. NONE ./
}
bsslap_elem_idx_t;
*/
elem_fcn bsslap_elem_fcn[] = {
    /* BSS LAP Elements 5 */
    NULL,            /* Reserved */
    de_ta,           /* Timing Advance */
    NULL,            /* Reserved */          /* (note) */
    NULL,            /* "Cell Identity */
    NULL,            /* "Reserved */         /* (note) */
    NULL,            /* "Reserved */         /* (note) */
    NULL,            /* "Reserved */         /* (note) */
    NULL,            /* "Channel Description */
    NULL,            /* "Reserved */         /* (note) */
    NULL,            /* Reserved */          /* (note) */
    NULL,            /* Reserved */          /* (note) */
    de_rr_meas_res,  /* "Measurement Report */
    NULL,            /* "Reserved */         /* (note) */
    de_bsslap_cause, /* "Cause */
    de_rrlp_flg,     /* "RRLP Flag */
    de_rrlp_ie,      /* "RRLP IE */
    de_cell_id_list, /* "Cell Identity List */
    de_enh_meas_rep, /* Enhanced Measurement Report */
    de_lac,          /* "Location Area Code */
    NULL,            /* "Frequency List */
    de_ms_pow,       /* MS Power */
    de_delta_time,   /* Delta Timer */
    NULL,            /* Serving Cell Identifier */
    de_blap_enc_key, /* Encryption Key (Kc) */
    NULL,            /* Cipher Mode Setting */
    NULL,            /* Channel Mode */
    de_poll_rep,     /* Polling Repetition */
    de_pkt_ch_desc,  /* Packet Channel Description */
    NULL,            /* TLLI */
    de_tfi,          /* TFI */
    NULL,            /* Starting Time */
    NULL,            /* NONE */
};

#define NUM_GSM_BSSLAP_MSG array_length(gsm_a_bsslap_msg_strings)
static int ett_gsm_bsslap_msg[NUM_GSM_BSSLAP_MSG];

/* 4.2.2 TA Response ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_ta_res(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Cell Identity IE / 5.4 M TV 3 */
    ELEM_MAND_TV(BSSLAP_PARAM_CELL_IDENTITY, GSM_A_PDU_TYPE_COMMON, DE_CELL_ID, "Serving Cell Identity", ei_gsm_bsslap_missing_mandatory_element);
    /* Timing Advance IE / 5.2 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_TIMING_ADVANCE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TA, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Measurement Report IE / 5.12 O TLV 18 */
    ELEM_OPT_TLV(BSSLAP_PARAM_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MEAS_REP, " BSSLAP");
    /* Enhanced Measurement Report IE / 5.18 O TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_ENHANCED_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENH_MEAS_REP, NULL);
    /* Cell Identity List IE / 5.17 O TLV 6-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_CELL_IDENTITY_LIST, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CELL_ID_LIST, "-Measured Cell");

    return;

}


/* 4.2.3 (void)   ETSI TS 148 071 V7.2.0 (2007-06) */
/* 4.2.4 (void)   ETSI TS 148 071 V7.2.0 (2007-06) */
/* 4.2.5 Reject   ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_reject(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Cause IE / 5.14 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_CAUSE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CAUSE, NULL, ei_gsm_bsslap_missing_mandatory_element);

    return;
}

/* 4.2.6 Reset   ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_reset(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Cell Identity IE / 5.4 M TV 3 */
    ELEM_MAND_TV(BSSLAP_PARAM_CELL_IDENTITY, GSM_A_PDU_TYPE_COMMON, DE_CELL_ID, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Timing Advance IE / 5.2 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_TIMING_ADVANCE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TA, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Channel Description IE / 5.8 M TV 4 */
    ELEM_MAND_TV(BSSLAP_PARAM_CHANNEL_DESCRIPTION,GSM_A_PDU_TYPE_RR, DE_RR_CH_DSC, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Cause IE / 5.1 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_CAUSE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CAUSE, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Measurement Report Measurement Report IE / 5.12 O TLV 18 */
    ELEM_OPT_TLV(BSSLAP_PARAM_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MEAS_REP, " BSSLAP");
    /* Enhanced Measurement Report Enhanced Measurement Report IE / 5.18 O TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_ENHANCED_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENH_MEAS_REP, NULL);
    /* Cell Identity List IE / 5.17 O TLV 6-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_CELL_IDENTITY_LIST, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CELL_ID_LIST, "-Measured Cell");
    /* LAC Location Area Code IE / 5.19 O TV 3 */
    ELEM_OPT_TLV(BSSLAP_PARAM_LOCATION_AREA_CODE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_LAC, NULL);
    /* Frequency List Frequency List IE 5.20 C (note 1) TLV 3-n  */
    ELEM_OPT_TLV(BSSLAP_PARAM_FREQUENCY_LIST, GSM_A_PDU_TYPE_RR, DE_RR_FREQ_LIST, NULL);
    /* Channel Mode IE 5.26 C (notes 2 & 4) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_CHANNEL_MODE, GSM_A_PDU_TYPE_RR, DE_RR_CH_MODE, NULL);
    /* MultiRate Configuration 5.27 C (notes 3 & 4) TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_MULTIRATE_CONFIGURATION, GSM_A_PDU_TYPE_RR, DE_RR_MULTIRATE_CONF, NULL);
    /* Packet Channel Description Packet Channel Description IE 5.29 C (note 5) TV 4 */
    ELEM_OPT_TLV(BSSLAP_PARAM_PACKET_CHANNEL_DESCRIPTION, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_PKT_CH_DESC, NULL);
    /* TLLI IE 5.30 C (note 5) TV 5 */
    ELEM_OPT_TV(BSSLAP_PARAM_TLLI, GSM_A_PDU_TYPE_RR, DE_RR_TLLI,NULL);
    /* TFI 5.31 C (note 5) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_TFI, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TFI,NULL);
    /* Starting Time IE 5.32 C (note 5) TV 3 */
    ELEM_OPT_TV(BSSLAP_PARAM_STARTING_TIME, GSM_A_PDU_TYPE_RR, DE_RR_STARTING_TIME, "TBF Starting Time");
    /* Encryption Key IE 5.24 C (note 4) TV 9 */
    ELEM_OPT_TV(BSSLAP_PARAM_ENCRYPTION_KEY, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENC_KEY,NULL);
    /* Cipher Mode Setting IE 5.25 C (note 4) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_CIPHER_MODE_SETTING, GSM_A_PDU_TYPE_RR, DE_RR_CIP_MODE_SET, NULL);
    return;
}

/* 4.2.7 Abort  ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_abort(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Cause IE / 5.14 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_CAUSE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CAUSE, NULL, ei_gsm_bsslap_missing_mandatory_element);

    return;
}
/* 4.2.8 TA Layer3  ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_ta_layer3(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Timing Advance IE / 5.2 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_TIMING_ADVANCE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TA, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Measurement Report IE / 5.12 O TLV 18 */
    ELEM_OPT_TLV(BSSLAP_PARAM_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MEAS_REP, " BSSLAP");
    /* Enhanced Measurement Report IE / 5.18 O TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_ENHANCED_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENH_MEAS_REP, NULL);
    /*Cell Identity List IE / 5.17 O TLV 6-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_CELL_IDENTITY_LIST, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CELL_ID_LIST, "-Measured Cell");
    return;
}
/* 4.2.9 MS Position Command  ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_ms_pos_cmd(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* RRLP flag IE / 5.15 M TV 2 */
    ELEM_MAND_TV(BSSLAP_PARAM_RRLP_FLAG, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_RRLP_FLG, "flag", ei_gsm_bsslap_missing_mandatory_element);
    /* RRLP IE / 5.16 M TLV 3-n */
    ELEM_MAND_TV(BSSLAP_PARAM_RRLP_IE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_RRLP_IE, "RRLP Info", ei_gsm_bsslap_missing_mandatory_element);
    return;
}
/* 4.2.10 MS Position Response   ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_ms_pos_res(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* flag RRLP flag IE / 5.15 M TV 2  */
    ELEM_MAND_TV(BSSLAP_PARAM_RRLP_FLAG, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_RRLP_FLG, "flag", ei_gsm_bsslap_missing_mandatory_element);
    /* RRLP Info RRLP IE / 5.16 M TLV 3-n */
    ELEM_MAND_TV(BSSLAP_PARAM_RRLP_IE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_RRLP_IE, "RRLP Info", ei_gsm_bsslap_missing_mandatory_element);
    /* Timing Advance IE / 5.2 O TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_TIMING_ADVANCE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TA, NULL);
    /* Measurement Report IE / 5.12 O TLV 18 */
    ELEM_OPT_TLV(BSSLAP_PARAM_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MEAS_REP, " BSSLAP");
    /* Enhanced Measurement Report IE / 5.18 O TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_ENHANCED_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENH_MEAS_REP, NULL);
    /* Cell Identity List IE / 5.17 O TLV 6-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_CELL_IDENTITY_LIST, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CELL_ID_LIST, "-Measured Cell");
    return;
}
/* 4.2.11 U-TDOA Request   ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_u_tdoa_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Delta Timer IE 5.22 O (note 1) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_DELTA_TIMER, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_DELTA_TIME, NULL);
    /*  Polling Repetition IE 5.28 (note) C (note 2) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_POLLING_REPETITION, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_POLL_REP, NULL);

    return;
}
/* 4.2.12 U-TDOA Response  ETSI TS 148 071 V7.2.0 (2007-06) */
static void
dissect_gsm_bsslap_u_tdoa_res(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len = tvb_reported_length_remaining(tvb,offset);

    /* Channel Description IE 5.8 M TV 4 */
    ELEM_MAND_TV(BSSLAP_PARAM_CHANNEL_DESCRIPTION,GSM_A_PDU_TYPE_RR, DE_RR_CH_DSC, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Serving Cell Identifier Cell Identifier IE 5.23 M TLV 4-n */
    ELEM_MAND_TLV(BSSLAP_PARAM_SERVING_CELL_IDENTIFIER,GSM_A_PDU_TYPE_BSSMAP, BE_CELL_ID, NULL, ei_gsm_bsslap_missing_mandatory_element);
    /* Frequency List IE 5.20 C (note 3) TLV 3-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_FREQUENCY_LIST, GSM_A_PDU_TYPE_RR, DE_RR_FREQ_LIST, NULL);
    /* Timing Advance IE 5.2 O TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_TIMING_ADVANCE, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TA, NULL);
    /* MS Power IE 5.21 O TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_MS_POWER, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MS_POW, NULL);
    /* Measurement Report IE 5.12 O TLV 18 */
    ELEM_OPT_TLV(BSSLAP_PARAM_MEASUREMENT_REPORT, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_MEAS_REP, " BSSLAP");
    /* Encryption Key IE 5.24 C (note 4) TV 9 */
    ELEM_OPT_TV(BSSLAP_PARAM_ENCRYPTION_KEY, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_ENC_KEY, NULL);
    /* Cipher Mode Setting IE 5.25 C (note 4) TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_CIPHER_MODE_SETTING, GSM_A_PDU_TYPE_RR, DE_RR_CIP_MODE_SET, NULL);
    /* Channel Mode IE 5.26 C (notes 1 & 4)TV 2 */
    ELEM_OPT_TV(BSSLAP_PARAM_CHANNEL_MODE, GSM_A_PDU_TYPE_RR, DE_RR_CH_MODE, NULL);
    /* MultiRate Configuration IE 5.27 C (notes 1 & 4)TLV 4-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_MULTIRATE_CONFIGURATION, GSM_A_PDU_TYPE_RR, DE_RR_MULTIRATE_CONF, NULL);
    /* Cell Identity List IE / 5.17 O TLV 6-n */
    ELEM_OPT_TLV(BSSLAP_PARAM_CELL_IDENTITY_LIST, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_CELL_ID_LIST, "-Measured Cell");
    /* Packet Channel Description IE 5.29 C (note 5) TV 4 */
    ELEM_OPT_TLV(BSSLAP_PARAM_PACKET_CHANNEL_DESCRIPTION, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_PKT_CH_DESC, NULL);
    /* TLLI IE 5.30 C (note 5) TV 5 */
    ELEM_OPT_TV(BSSLAP_PARAM_TLLI, GSM_A_PDU_TYPE_RR, DE_RR_TLLI, NULL);
    /* TFI IE 5.31 C (note 5) TV 2 BSSLAP_PARAM_TFI*/
    ELEM_OPT_TV(BSSLAP_PARAM_TFI, GSM_A_PDU_TYPE_BSSLAP, DE_BLAP_TFI, NULL);
    /* Starting Time IE 5.32 C (note 5) TV 3*/
    ELEM_OPT_TV(BSSLAP_PARAM_STARTING_TIME, GSM_A_PDU_TYPE_RR, DE_RR_STARTING_TIME, "TBF Starting Time");
    return;
}


static int
dissect_gsm_bsslap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_item *item;
    proto_tree *sub_tree;
    int offset=0;
    uint8_t octet;

/* Make entries in Protocol column and Info column on summary display */
    col_append_str(pinfo->cinfo, COL_PROTOCOL, "/BSSLAP");
    if (tree) {
        octet = tvb_get_uint8(tvb, offset);
        item = proto_tree_add_item(tree, proto_gsm_bsslap, tvb, 0, -1, ENC_NA);
        sub_tree = proto_item_add_subtree(item, ett_gsm_bsslap);

        /* Message Type IE / 5.1 M V 1 */
        proto_tree_add_item(sub_tree, hf_gsm_bsslap_msg_type, tvb, offset, 1, ENC_BIG_ENDIAN);
        offset++;

        switch (octet){
        case BSSLAP_TA_REQUEST:
            /* Only message type IE */
            break;
        case BSSLAP_TA_RESPONSE:
            dissect_gsm_bsslap_ta_res(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_REJECT:
            dissect_gsm_bsslap_reject(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_RESET:
            dissect_gsm_bsslap_reset(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_ABORT:
            dissect_gsm_bsslap_abort(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_TA_LAYER3:
            dissect_gsm_bsslap_ta_layer3(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_MS_POS_CMD:
            dissect_gsm_bsslap_ms_pos_cmd(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_MS_POS_RES:
            dissect_gsm_bsslap_ms_pos_res(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_U_TDOA_REQ:
            dissect_gsm_bsslap_u_tdoa_req(tvb, sub_tree, pinfo, offset);
            break;
        case BSSLAP_U_TDOA_RES:
            dissect_gsm_bsslap_u_tdoa_res(tvb, sub_tree, pinfo, offset);
            break;
        default:
            break;
        }
    }

    return tvb_captured_length(tvb);
}

void
proto_reg_handoff_gsm_bsslap(void)
{
    bsslap_rrlp_handle = find_dissector_add_dependency("rrlp", proto_gsm_bsslap);
}

void
proto_register_gsm_bsslap(void)
{
    unsigned    i;
    unsigned    last_offset;


    /* Setup list of header fields */
    static hf_register_info hf[] = {
        { &hf_gsm_bsslap_msg_type,
            { "Message Type IE",           "gsm_bsslap.msg_type",
            FT_UINT8, BASE_DEC, VALS(gsm_a_bsslap_msg_strings), 0x0,
            NULL, HFILL }
        },
        { &hf_gsm_a_bsslap_elem_id,
            { "Element ID", "gsm_bsslap.elem_id",
            FT_UINT8, BASE_HEX, NULL, 0,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_ta,
            { "Timing Advance",           "gsm_bsslap.ta",
            FT_UINT8, BASE_HEX, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_timer_value,
            {"Timer Value", "gsm_bsslap.timerValue",
            FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },

        { &hf_gsm_bsslap_ms_pow,
            {"MS Power", "gsm_bsslap.MS_pow",
            FT_UINT8, BASE_DEC, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_cause,
            {"Cause", "gsm_bsslap.cause",
            FT_UINT8, BASE_DEC, VALS(gsm_bsslap_cause_vals), 0x0,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_rrlp_flg,
            {"RRLP Flag", "gsm_bsslap.rrlp_flg",
            FT_BOOLEAN, 8, TFS(&gsm_bsslap_rrlp_flg_vals), 0x01,
            "Cause", HFILL }
        },
        { &hf_gsm_bsslap_tfi,
            {"TFI", "gsm_bsslap.tfi",
            FT_UINT8, BASE_DEC, NULL, 0x1f,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_poll_rep,
            {"Number of polling repetitions", "gsm_bsslap.poll_rep",
            FT_UINT8, BASE_DEC, NULL, 0x3F,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_lac,
            {"Location Area Code", "gsm_bsslap.lac",
            FT_UINT8, BASE_DEC, NULL, 0x3f,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_cell_id_disc,
            {"Cell identification Discriminator", "gsm_bsslap.cell_id_disc",
            FT_UINT8, BASE_DEC, VALS(gsm_a_bsslap_cell_id_disc_vals), 0xf,
            NULL, HFILL }
        },
        { &hf_gsm_bsslap_encryption_key,
            {"Encryption Key (Kc)", "gsm_bsslap.encryption_key",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
    };

    static ei_register_info ei[] = {
        { &ei_gsm_bsslap_missing_mandatory_element, { "gsm_bsslap.missing_mandatory_element", PI_PROTOCOL, PI_WARN, "Missing Mandatory element, rest of dissection is suspect", EXPFILL }},
        { &ei_gsm_bsslap_not_decoded_yet, { "gsm_bsslap.not_decoded_yet", PI_UNDECODED, PI_WARN, "Not decoded yet", EXPFILL }},
    };

    expert_module_t* expert_gsm_bsslap;

    /* Setup protocol subtree array */
#define NUM_INDIVIDUAL_ELEMS    2
    int *ett[NUM_INDIVIDUAL_ELEMS + NUM_GSM_BSSLAP_MSG +
          NUM_GSM_BSSLAP_ELEM];

    ett[0] = &ett_gsm_bsslap;
    ett[1] = &ett_bsslap_cell_list;

    last_offset = NUM_INDIVIDUAL_ELEMS;

    for (i=0; i < NUM_GSM_BSSLAP_MSG; i++, last_offset++)
    {
        ett[last_offset] = &ett_gsm_bsslap_msg[i];
    }

    for (i=0; i < NUM_GSM_BSSLAP_ELEM; i++, last_offset++)
    {
        ett[last_offset] = &ett_gsm_bsslap_elem[i];
    }


/* Register the protocol name and description */
    proto_gsm_bsslap =
        proto_register_protocol("BSS LCS Assistance Protocol",
        "BSSLAP", "bsslap");

/* Required function calls to register the header fields and subtrees used */
    proto_register_field_array(proto_gsm_bsslap, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_gsm_bsslap = expert_register_protocol(proto_gsm_bsslap);
    expert_register_field_array(expert_gsm_bsslap, ei, array_length(ei));

    register_dissector("gsm_bsslap", dissect_gsm_bsslap, proto_gsm_bsslap);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */