epan/dissectors/packet-lapsat.c

   1 /* packet-lapsat.c
   2  *
   3  * Routines for GMR-1 LAPSat dissection in wireshark.
   4  *
   5  * Link Access Procedures (LAP) for the Satellite Channel (LAPSat).
   6  * LAPSat is the protocol for signalling transfer between an Access
   7  * Terminal (MES) and a Gateway Station (GS) in the GeoMobile (GMR-1) network.
   8  *
   9  * Copyright (c) 2011 Sylvain Munaut <tnt@246tNt.com>
  10  * Inspired on LAPDm code by Duncan Salerno <duncan.salerno@googlemail.com>
  11  *
  12  * References:
  13  *  [1] ETSI TS 101 376-4-6 V1.2.1 - GMR-1 04.006
  14  *
  15  * $Id$
  16  *
  17  * Wireshark - Network traffic analyzer
  18  * By Gerald Combs <gerald@wireshark.org>
  19  * Copyright 1998 Gerald Combs
  20  *
  21  * This program is free software; you can redistribute it and/or
  22  * modify it under the terms of the GNU General Public License
  23  * as published by the Free Software Foundation; either version 2
  24  * of the License, or (at your option) any later version.
  25  *
  26  * This program is distributed in the hope that it will be useful,
  27  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  * GNU General Public License for more details.
  30  *
  31  * You should have received a copy of the GNU General Public License
  32  * along with this program; if not, write to the Free Software
  33  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  34  */
  35
  36 #include "config.h"
  37
  38 #include <glib.h>
  39 #include <epan/packet.h>
  40 #include <epan/reassemble.h>
  41 #include <epan/wmem/wmem.h>
  42
  43
  44 static int proto_lapsat = -1;
  45
  46 static reassembly_table lapsat_reassembly_table;
  47
  48 static dissector_table_t lapsat_sapi_dissector_table;
  49
  50 static dissector_handle_t data_handle;
  51
  52 static gint ett_lapsat = -1;
  53 static gint ett_lapsat_address = -1;
  54 static gint ett_lapsat_control = -1;
  55 static gint ett_lapsat_fragment = -1;
  56 static gint ett_lapsat_fragments = -1;
  57
  58 static int hf_lapsat_addr = -1;
  59 static int hf_lapsat_addr_sst = -1;
  60 static int hf_lapsat_addr_cr = -1;
  61 static int hf_lapsat_addr_sapi = -1;
  62 static int hf_lapsat_addr_si = -1;
  63 static int hf_lapsat_addr_lpd = -1;
  64 static int hf_lapsat_addr_lfi = -1;
  65
  66 static int hf_lapsat_ctl = -1;
  67 static int hf_lapsat_ctl_ftype_i = -1;
  68 static int hf_lapsat_ctl_ftype_s_u = -1;
  69 static int hf_lapsat_ctl_s_ftype = -1;
  70 static int hf_lapsat_ctl_u_modifier_cmd = -1;
  71 static int hf_lapsat_ctl_u_modifier_resp = -1;
  72 static int hf_lapsat_ctl_n_r = -1;
  73 static int hf_lapsat_ctl_n_s = -1;
  74 static int hf_lapsat_ctl_p = -1;
  75 static int hf_lapsat_ctl_f = -1;
  76 static int hf_lapsat_ctl_mii = -1;
  77
  78 static int hf_lapsat_payload_last_nibble = -1;
  79
  80 static int hf_lapsat_len = -1;
  81
  82 static int hf_lapsat_fragments = -1;
  83 static int hf_lapsat_fragment = -1;
  84 static int hf_lapsat_fragment_overlap = -1;
  85 static int hf_lapsat_fragment_overlap_conflicts = -1;
  86 static int hf_lapsat_fragment_multiple_tails = -1;
  87 static int hf_lapsat_fragment_too_long_fragment = -1;
  88 static int hf_lapsat_fragment_error = -1;
  89 static int hf_lapsat_fragment_count = -1;
  90 static int hf_lapsat_reassembled_in = -1;
  91 static int hf_lapsat_reassembled_length = -1;
  92
  93
  94 #define LAPSAT_HEADER_LEN               3
  95
  96 #define LAPSAT_SAPI_RR_CC_MM            0
  97 #define LAPSAT_SAPI_SMS                 3
  98
  99
 100 /*
 101  * Address field bits
 102  */
 103
 104 #define LAPSAT_SST                      0x01    /* SACCH status bit */
 105 #define LAPSAT_CR                       0x02    /* Command/Response bit */
 106 #define LAPSAT_SAPI_MSK                 0x0c    /* Service Access Point Identifier */
 107 #define LAPSAT_SAPI_SHIFT               2
 108 #define LAPSAT_SI                       0x10    /* Segment Indicator */
 109 #define LAPSAT_LPD_MSK                  0x60    /* DL for LAPSat or SMS-CB */
 110 #define LAPSAT_LPD_SHIFT                6
 111 #define LAPSAT_LFI                      0x80    /* Length Field Indicator */
 112
 113 static const value_string lapsat_addr_sst_vals[] = {
 114         { 0, "FACCH and all other messages" },
 115         { 1, "SACCH message" },
 116         { 0 , NULL }
 117 };
 118
 119 static const value_string lapsat_addr_sapi_vals[] = {
 120         { LAPSAT_SAPI_RR_CC_MM, "RR/MM/CC" },
 121         { LAPSAT_SAPI_SMS, "SMS/SS" },
 122         { 0, NULL }
 123 };
 124
 125 static const value_string lapsat_addr_lpd_vals[] = {
 126         { 0, "Normal GMR-1" },
 127         { 1, "Cell broadcast service" },
 128         { 0, NULL }
 129 };
 130
 131 static const value_string lapsat_addr_si_vals[] = {
 132         { 0, "Complete/Last Segment of L3 message" },
 133         { 1, "Segment only" },
 134         { 0, NULL }
 135 };
 136
 137 static const value_string lapsat_addr_lfi_vals[] = {
 138         { 0, "Length Field not present (all data valid)" },
 139         { 1, "Length Field present" },
 140         { 0, NULL }
 141 };
 142
 143
 144 /*
 145  * Frame types
 146  */
 147
 148 #define LAPSAT_CTL_TYPE_S               0x001
 149 #define LAPSAT_CTL_TYPE_U               0x003
 150 #define LAPSAT_CTL_TYPE_S_U_MSK         0x003
 151
 152 #define LAPSAT_CTL_TYPE_I               0x000
 153 #define LAPSAT_CTL_TYPE_I_MSK           0x001
 154
 155 static const value_string lapsat_ctl_ftype_vals[] = {
 156         { LAPSAT_CTL_TYPE_I, "Information frame" },
 157         { LAPSAT_CTL_TYPE_S, "Supervisory frame" },
 158         { LAPSAT_CTL_TYPE_U, "Unnumbered frame" },
 159         { 0, NULL }
 160 };
 161
 162
 163 /*
 164  * S-format frame types
 165  */
 166
 167 #define LAPSAT_CTL_S_FTYPE_MSK          0x00c
 168
 169 #define LAPSAT_RR                       0x000
 170 #define LAPSAT_GREJ                     0x008
 171
 172 static const value_string lapsat_ctl_s_ftype_vals[] = {
 173         { LAPSAT_RR >> 2,   "Receiver ready" },
 174         { LAPSAT_GREJ >> 2, "Group reject" },
 175         { 0, NULL}
 176 };
 177
 178
 179 /*
 180  * U-format modifiers
 181  */
 182
 183 #define LAPSAT_CTL_U_MODIFIER_MSK       0x18c
 184
 185 #define LAPSAT_SABM                     0x08c
 186 #define LAPSAT_DM                       0x00c
 187 #define LAPSAT_DISC                     0x100
 188 #define LAPSAT_UA                       0x180
 189 #define LAPSAT_UI                       0x000
 190
 191 static const value_string lapsat_ctl_u_modifier_vals_cmd[] = {
 192         { LAPSAT_SABM >> 2, "Set Asynchronous Balanced Mode" },
 193         { LAPSAT_DISC >> 2, "Disconnect" },
 194         { LAPSAT_UI >> 2,   "Unnumbered Information" },
 195         { 0, NULL}
 196 };
 197
 198 static const value_string lapsat_ctl_u_modifier_vals_resp[] = {
 199         { LAPSAT_DM >> 2,   "Disconnected mode" },
 200         { LAPSAT_UA >> 2,   "Unnumbered Acknowledge" },
 201         { 0, NULL}
 202 };
 203
 204
 205 /*
 206  * Control fields
 207  */
 208
 209 #define LAPSAT_CTL_P_F                  0x040
 210 #define LAPSAT_CTL_MII                  0x200
 211 #define LAPSAT_CTL_N_R_MSK              0xf80
 212 #define LAPSAT_CTL_N_R_SHIFT            7
 213 #define LAPSAT_CTL_N_S_MSK              0x03e
 214 #define LAPSAT_CTL_N_S_SHIFT            1
 215
 216
 217 /*
 218  * Fragment stuff
 219  */
 220
 221 static const value_string true_false_vals[] = {
 222         { 0, "False" },
 223         { 1, "True" },
 224         { 0, NULL },
 225 };
 226
 227
 228 static const fragment_items lapsat_frag_items = {
 229         /* Fragment subtrees */
 230         &ett_lapsat_fragment,
 231         &ett_lapsat_fragments,
 232         /* Fragment fields */
 233         &hf_lapsat_fragments,
 234         &hf_lapsat_fragment,
 235         &hf_lapsat_fragment_overlap,
 236         &hf_lapsat_fragment_overlap_conflicts,
 237         &hf_lapsat_fragment_multiple_tails,
 238         &hf_lapsat_fragment_too_long_fragment,
 239         &hf_lapsat_fragment_error,
 240         &hf_lapsat_fragment_count,
 241         /* Reassembled in field */
 242         &hf_lapsat_reassembled_in,
 243         /* Reassembled length field */
 244         &hf_lapsat_reassembled_length,
 245         /* Reassembled data field */
 246         NULL,
 247         /* Tag */
 248         "fragments"
 249 };
 250
 251 static void
 252 lapsat_defragment_init(void)
 253 {
 254         reassembly_table_init(&lapsat_reassembly_table,
 255             &addresses_reassembly_table_functions);
 256 }
 257
 258
 259 /*
 260  * Main dissection functions
 261  */
 262
 263 static guint16
 264 dissect_control(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int is_response)
 265 {
 266         proto_tree *ctl_tree;
 267         proto_item *ctl_ti;
 268         guint16 ctl, poll_final;
 269         const char *frame_type;
 270         char *info;
 271
 272         info = (char *)wmem_alloc(wmem_packet_scope(), 80);
 273
 274         /* Grab complete control field */
 275         ctl = tvb_get_ntohs(tvb, 1) >> 4;
 276
 277         poll_final = ctl & LAPSAT_CTL_P_F;
 278
 279         /* Generate small 'descriptive' text */
 280         switch (ctl & LAPSAT_CTL_TYPE_S_U_MSK) {
 281         case LAPSAT_CTL_TYPE_S:
 282                 /*
 283                  * Supervisory frame.
 284                  */
 285                 switch (ctl & LAPSAT_CTL_S_FTYPE_MSK) {
 286                 case LAPSAT_RR:
 287                         frame_type = "RR";
 288                         break;
 289                 case LAPSAT_GREJ:
 290                         frame_type = "GREJ";
 291                         break;
 292                 default:
 293                         frame_type = "Unknown";
 294                         break;
 295                 }
 296
 297                 g_snprintf(info, 80, "S%s, func=%s, N(R)=%u",
 298                         poll_final ? (is_response ? " F" : " P") : "",
 299                         frame_type,
 300                         (ctl & LAPSAT_CTL_N_R_MSK) >> LAPSAT_CTL_N_R_SHIFT);
 301
 302                 break;
 303
 304         case LAPSAT_CTL_TYPE_U:
 305                 /*
 306                  * Unnumbered frame
 307                  */
 308                 switch (ctl & LAPSAT_CTL_U_MODIFIER_MSK) {
 309                 case LAPSAT_SABM:
 310                         frame_type = (ctl & LAPSAT_CTL_MII) ?
 311                                 "SABM, MII=1" : "SABM, MII=0";
 312                         break;
 313                 case LAPSAT_DM:
 314                         frame_type = "DM";
 315                         break;
 316                 case LAPSAT_DISC:
 317                         frame_type = "DISC";
 318                         break;
 319                 case LAPSAT_UA:
 320                         frame_type = "UA";
 321                         break;
 322                 case LAPSAT_UI:
 323                         frame_type = "UI";
 324                         break;
 325                 default:
 326                         frame_type = "Unknown";
 327                         break;
 328                 }
 329
 330                 g_snprintf(info, 80, "U%s, func=%s",
 331                         poll_final ? (is_response ? " F" : " P") : "",
 332                         frame_type);
 333
 334                 break;
 335
 336         default:
 337                 /*
 338                  * Information frame
 339                  */
 340                 g_snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u",
 341                         poll_final ? " P" : "",
 342                         (ctl & LAPSAT_CTL_N_R_MSK) >> LAPSAT_CTL_N_R_SHIFT,
 343                         (ctl & LAPSAT_CTL_N_S_MSK) >> LAPSAT_CTL_N_S_SHIFT);
 344
 345                 break;
 346         }
 347
 348         /* Add info */
 349         col_add_str(pinfo->cinfo, COL_INFO, info);
 350
 351         /* Create item & subtree */
 352         ctl_ti = proto_tree_add_uint_format_value(
 353                         tree, hf_lapsat_ctl,
 354                         tvb, 1, 2, (guint32)ctl,
 355                         "%s (0x%03x)", info, ctl
 356         );
 357
 358         ctl_tree = proto_item_add_subtree(ctl_ti, ett_lapsat_control);
 359
 360         /* Add all fields */
 361         switch (ctl & LAPSAT_CTL_TYPE_S_U_MSK) {
 362         case LAPSAT_CTL_TYPE_S:
 363                 /*
 364                  * Supervisory frame.
 365                  */
 366
 367                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_ftype_s_u,
 368                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 369
 370                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_s_ftype,
 371                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 372
 373                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_n_r,
 374                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 375
 376                 if (poll_final)
 377                         proto_tree_add_item(ctl_tree,
 378                                 is_response ? hf_lapsat_ctl_f : hf_lapsat_ctl_p,
 379                                 tvb, 1, 2, ENC_BIG_ENDIAN);
 380
 381                 break;
 382
 383         case LAPSAT_CTL_TYPE_U:
 384                 /*
 385                  * Unnumbered frame
 386                  */
 387
 388                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_ftype_s_u,
 389                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 390
 391                 proto_tree_add_item(ctl_tree,
 392                         is_response ?   hf_lapsat_ctl_u_modifier_resp :
 393                                         hf_lapsat_ctl_u_modifier_cmd,
 394                         tvb, 1, 2, ENC_BIG_ENDIAN);
 395
 396                 if (poll_final)
 397                         proto_tree_add_item(ctl_tree,
 398                                 is_response ? hf_lapsat_ctl_f : hf_lapsat_ctl_p,
 399                                 tvb, 1, 2, ENC_BIG_ENDIAN);
 400
 401                 if (((ctl & LAPSAT_CTL_U_MODIFIER_MSK) == LAPSAT_SABM) &&
 402                      (ctl & LAPSAT_CTL_MII))
 403                         proto_tree_add_item(ctl_tree, hf_lapsat_ctl_mii,
 404                                             tvb, 1, 2, ENC_BIG_ENDIAN);
 405
 406                 break;
 407
 408         default:
 409                 /*
 410                  * Information frame
 411                  */
 412
 413                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_ftype_i,
 414                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 415
 416                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_n_r,
 417                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 418
 419                 proto_tree_add_item(ctl_tree, hf_lapsat_ctl_n_s,
 420                                     tvb, 1, 2, ENC_BIG_ENDIAN);
 421
 422                 if (poll_final)
 423                         proto_tree_add_item(ctl_tree, hf_lapsat_ctl_p,
 424                                             tvb, 1, 2, ENC_BIG_ENDIAN);
 425
 426                 break;
 427         }
 428
 429         return ctl;
 430 }
 431
 432 static void
 433 dissect_lapsat(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 434 {
 435         proto_tree *lapsat_tree, *addr_tree;
 436         proto_item *lapsat_ti, *addr_ti;
 437         tvbuff_t *payload;
 438         guint8 addr, sapi, cr;
 439         guint16 control;
 440         unsigned int hlen, is_response = 0, plen;
 441
 442         /* Check that there's enough data */
 443         if (tvb_length(tvb) < LAPSAT_HEADER_LEN)
 444                 return;
 445
 446         /* Set protocol column */
 447         col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPSat");
 448
 449         /* Grab a couple of fields */
 450         addr = tvb_get_guint8(tvb, 0);
 451
 452         sapi = (addr & LAPSAT_SAPI_MSK) >> LAPSAT_SAPI_SHIFT;
 453
 454         cr = addr & LAPSAT_CR;
 455         if (pinfo->p2p_dir == P2P_DIR_RECV) {
 456                 is_response = cr ? FALSE : TRUE;
 457         }
 458         else if (pinfo->p2p_dir == P2P_DIR_SENT) {
 459                 is_response = cr ? TRUE : FALSE;
 460         }
 461
 462         hlen = LAPSAT_HEADER_LEN;
 463
 464         if (addr & LAPSAT_LFI)
 465                 hlen++;
 466
 467                 /* FIXME if "S func=GREJ", extend */
 468
 469         /* Create LAPSat tree */
 470         lapsat_ti = proto_tree_add_item(tree, proto_lapsat, tvb, 0, hlen, ENC_BIG_ENDIAN);
 471         lapsat_tree = proto_item_add_subtree(lapsat_ti, ett_lapsat);
 472
 473         /* Dissect address field */
 474         addr_ti = proto_tree_add_item(lapsat_tree, hf_lapsat_addr, tvb, 0, 1, ENC_BIG_ENDIAN);
 475         addr_tree = proto_item_add_subtree(addr_ti, ett_lapsat_address);
 476
 477         proto_tree_add_item(addr_tree, hf_lapsat_addr_sst,  tvb, 0, 1, ENC_BIG_ENDIAN);
 478         proto_tree_add_item(addr_tree, hf_lapsat_addr_cr,   tvb, 0, 1, ENC_BIG_ENDIAN);
 479         proto_tree_add_item(addr_tree, hf_lapsat_addr_sapi, tvb, 0, 1, ENC_BIG_ENDIAN);
 480         proto_tree_add_item(addr_tree, hf_lapsat_addr_si,   tvb, 0, 1, ENC_BIG_ENDIAN);
 481         proto_tree_add_item(addr_tree, hf_lapsat_addr_lpd,  tvb, 0, 1, ENC_BIG_ENDIAN);
 482         proto_tree_add_item(addr_tree, hf_lapsat_addr_lfi,  tvb, 0, 1, ENC_BIG_ENDIAN);
 483
 484         /* Dissect control field */
 485         control = dissect_control(tvb, pinfo, lapsat_tree, is_response);
 486
 487         /* Last payload nibble */
 488         proto_tree_add_item(lapsat_tree, hf_lapsat_payload_last_nibble, tvb, 2, 1, ENC_BIG_ENDIAN);
 489
 490         /* Optional length field */
 491         if (addr & LAPSAT_LFI)
 492                 proto_tree_add_item(lapsat_tree, hf_lapsat_len, tvb, 3, 1, ENC_BIG_ENDIAN);
 493
 494         /* If frame is "S func=GREJ", then add Na(R) & Nb(R) */
 495                 /* FIXME */
 496
 497         /* Get the payload */
 498         plen = (addr & LAPSAT_LFI) ?
 499                 tvb_get_guint8(tvb, 3) : tvb_length(tvb) - hlen;
 500
 501         if (!plen)
 502                 return; /* No point in doing more if there is no payload */
 503
 504         DISSECTOR_ASSERT((plen + hlen) <= tvb_length(tvb));
 505
 506         if ((plen + hlen) == tvb_length(tvb)) {
 507                 /* Need to integrate the last nibble */
 508                 guint8 *data = (guint8 *)tvb_memdup(NULL, tvb, hlen, plen);
 509                 data[plen-1] |= tvb_get_guint8(tvb, 2) << 4;
 510                 payload = tvb_new_child_real_data(tvb, data, plen, plen);
 511                 tvb_set_free_cb(payload, g_free);
 512         } else {
 513                 /* Last nibble doesn't need merging */
 514                 payload = tvb_new_subset(tvb, hlen, plen, -1);
 515         }
 516
 517         add_new_data_source(pinfo, payload, "LAPSat Payload");
 518
 519         /* Handle fragments */
 520         if ((control & LAPSAT_CTL_TYPE_I_MSK) == LAPSAT_CTL_TYPE_I) {
 521                 /*
 522                  * Potentially fragmented I frames
 523                  */
 524                 fragment_head *fd_m = NULL;
 525                 tvbuff_t *reassembled = NULL;
 526                 guint32 fragment_id;
 527                 gboolean save_fragmented = pinfo->fragmented;
 528
 529                 /* Is this a fragment ? */
 530                 pinfo->fragmented = !!(addr & LAPSAT_SI);
 531
 532                 /* Rely on caller to provide a way to group fragments */
 533                 fragment_id = (pinfo->circuit_id << 3) | (sapi << 1) | pinfo->p2p_dir;
 534
 535                 /* Fragment reconstruction helpers */
 536                 fd_m = fragment_add_seq_next(
 537                         &lapsat_reassembly_table,
 538                         payload, 0,
 539                         pinfo,
 540                         fragment_id,            /* To group fragments */
 541                         NULL,
 542                         plen,
 543                         !!(addr & LAPSAT_SI)    /* More fragment ? */
 544                 );
 545
 546                 reassembled = process_reassembled_data(
 547                         payload, 0, pinfo,
 548                         "Reassembled LAPSat", fd_m, &lapsat_frag_items,
 549                         NULL, lapsat_tree
 550                 );
 551
 552                 /* Reassembled into this packet ? */
 553                 if (fd_m && pinfo->fd->num == fd_m->reassembled_in) {
 554                         /* Yes, so handoff to upper layers */
 555                         if (!dissector_try_uint(lapsat_sapi_dissector_table, sapi,
 556                                                 reassembled, pinfo, tree))
 557                                 call_dissector(data_handle, reassembled, pinfo, tree);
 558                 } else {
 559                         /* No, just add infos */
 560                         col_append_str(pinfo->cinfo, COL_INFO, " (Fragment)");
 561                         proto_tree_add_text(lapsat_tree, payload, 0, -1, "Fragment Data");
 562                 }
 563
 564                 /* Now reset fragmentation information in pinfo */
 565                 pinfo->fragmented = save_fragmented;
 566         } else {
 567                 /*
 568                  * Whole frame
 569                  */
 570                 if (!dissector_try_uint(lapsat_sapi_dissector_table, sapi, payload, pinfo, tree))
 571                         call_dissector(data_handle, payload, pinfo, tree);
 572         }
 573 }
 574
 575 void
 576 proto_register_lapsat(void)
 577 {
 578         static hf_register_info hf[] = {
 579                 /* Address field */
 580                 { &hf_lapsat_addr,
 581                   { "Address Field", "lapsat.address",
 582                     FT_UINT8, BASE_HEX, NULL, 0x00,
 583                     NULL, HFILL },
 584                 },
 585                 { &hf_lapsat_addr_sst,
 586                   { "SST", "lapsat.address.sst",
 587                     FT_UINT8, BASE_DEC, VALS(lapsat_addr_sst_vals), LAPSAT_SST,
 588                     "SACCH status bit", HFILL },
 589                 },
 590                 { &hf_lapsat_addr_cr,
 591                   { "C/R", "lapsat.address.cr",
 592                     FT_UINT8, BASE_DEC, NULL, LAPSAT_CR,
 593                     "Command/response bit", HFILL },
 594                 },
 595                 { &hf_lapsat_addr_sapi,
 596                   { "SAPI", "lapsat.address.sapi",
 597                     FT_UINT8, BASE_DEC, VALS(lapsat_addr_sapi_vals), LAPSAT_SAPI_MSK,
 598                     "Service access point identifier", HFILL },
 599                 },
 600                 { &hf_lapsat_addr_si,
 601                   { "SI", "lapsat.address.si",
 602                     FT_UINT8, BASE_DEC, VALS(lapsat_addr_si_vals), LAPSAT_SI,
 603                     "Segment Indicator", HFILL },
 604                 },
 605                 { &hf_lapsat_addr_lpd,
 606                   { "LPD", "lapsat.address.lpd",
 607                     FT_UINT8, BASE_DEC, VALS(lapsat_addr_lpd_vals), LAPSAT_LPD_MSK,
 608                     "Link Protocol Discriminator", HFILL },
 609                 },
 610                 { &hf_lapsat_addr_lfi,
 611                   { "LFI", "lapsat.address.lfi",
 612                     FT_UINT8, BASE_DEC, VALS(lapsat_addr_lfi_vals), LAPSAT_LFI,
 613                     "Length Field Indicator", HFILL },
 614                 },
 615
 616                 /* Control field */
 617                 { &hf_lapsat_ctl,
 618                   { "Control Field", "lapsat.control_field",
 619                     FT_UINT16, BASE_HEX, NULL, 0x00,
 620                     NULL, HFILL }
 621                 },
 622                 { &hf_lapsat_ctl_ftype_i,
 623                   { "Frame type", "lapsat.control.ftype",
 624                     FT_UINT16, BASE_DEC, VALS(lapsat_ctl_ftype_vals), LAPSAT_CTL_TYPE_I_MSK << 4,
 625                     NULL, HFILL }
 626                 },
 627                 { &hf_lapsat_ctl_ftype_s_u,
 628                   { "Frame type", "lapsat.control.ftype",
 629                     FT_UINT16, BASE_DEC, VALS(lapsat_ctl_ftype_vals), LAPSAT_CTL_TYPE_S_U_MSK << 4,
 630                     NULL, HFILL }
 631                 },
 632                 { &hf_lapsat_ctl_s_ftype,
 633                   { "Supervisory frame type", "lapsat.control.s_ftype",
 634                     FT_UINT16, BASE_DEC, VALS(lapsat_ctl_s_ftype_vals), LAPSAT_CTL_S_FTYPE_MSK << 4,
 635                     NULL, HFILL }
 636                 },
 637                 { &hf_lapsat_ctl_u_modifier_cmd,
 638                   { "Command", "lapsat.control.u_modifier_cmd",
 639                     FT_UINT16, BASE_HEX, VALS(lapsat_ctl_u_modifier_vals_cmd),
 640                     LAPSAT_CTL_U_MODIFIER_MSK << 4,
 641                     NULL, HFILL }
 642                 },
 643                 { &hf_lapsat_ctl_u_modifier_resp,
 644                   { "Response", "lapsat.control.u_modifier_resp",
 645                     FT_UINT16, BASE_HEX, VALS(lapsat_ctl_u_modifier_vals_resp),
 646                     LAPSAT_CTL_U_MODIFIER_MSK << 4,
 647                     NULL, HFILL }
 648                 },
 649                 { &hf_lapsat_ctl_n_r,
 650                   { "N(R)", "lapsat.control.n_r",
 651                     FT_UINT16, BASE_DEC, NULL, LAPSAT_CTL_N_R_MSK << 4,
 652                     NULL, HFILL }
 653                 },
 654                 { &hf_lapsat_ctl_n_s,
 655                   { "N(S)", "lapsat.control.n_s",
 656                     FT_UINT16, BASE_DEC, NULL, LAPSAT_CTL_N_S_MSK << 4,
 657                     NULL, HFILL }
 658                 },
 659                 { &hf_lapsat_ctl_p,
 660                   { "Poll", "lapsat.control.p",
 661                     FT_UINT16, BASE_DEC, VALS(true_false_vals), LAPSAT_CTL_P_F << 4,
 662                     NULL, HFILL }
 663                 },
 664                 { &hf_lapsat_ctl_f,
 665                   { "Final", "lapsat.control.f",
 666                     FT_UINT16, BASE_DEC, VALS(true_false_vals), LAPSAT_CTL_P_F << 4,
 667                     NULL, HFILL }
 668                 },
 669                 { &hf_lapsat_ctl_mii,
 670                   { "MII", "lapsat.control.mii",
 671                     FT_UINT16, BASE_DEC, VALS(true_false_vals), LAPSAT_CTL_MII << 4,
 672                     "Mobile Identity Indicator", HFILL }
 673                 },
 674
 675                 /* Payload last nibble */
 676                 { &hf_lapsat_payload_last_nibble,
 677                   { "Payload last nibble", "lapsat.payload.last_nibble",
 678                     FT_UINT8, BASE_HEX, NULL, 0x0f,
 679                     NULL, HFILL }
 680                 },
 681
 682                 /* Length field */
 683                 { &hf_lapsat_len,
 684                   { "Length Field", "lapsat.length",
 685                     FT_UINT8, BASE_DEC, NULL, 0x00,
 686                     NULL, HFILL },
 687                 },
 688
 689                 /* Fragment reassembly */
 690                 { &hf_lapsat_fragments,
 691                   { "Message fragments", "lapsat.fragments",
 692                     FT_NONE, BASE_NONE, NULL, 0x00,
 693                     "LAPSat Message fragments", HFILL }
 694                 },
 695                 { &hf_lapsat_fragment,
 696                   { "Message fragment", "lapsat.fragment",
 697                     FT_FRAMENUM, BASE_NONE, NULL, 0x00,
 698                     "LAPSat Message fragment", HFILL }
 699                 },
 700                 { &hf_lapsat_fragment_overlap,
 701                   { "Message fragment overlap", "lapsat.fragment.overlap",
 702                     FT_BOOLEAN, BASE_NONE, NULL, 0x0,
 703                     "LAPSat Message fragment overlaps with other fragment(s)", HFILL }
 704                 },
 705                 { &hf_lapsat_fragment_overlap_conflicts,
 706                   { "Message fragment overlapping with conflicting data",
 707                     "lapsat.fragment.overlap.conflicts",
 708                     FT_BOOLEAN, BASE_NONE, NULL, 0x0,
 709                     "LAPSat Message fragment overlaps with conflicting data", HFILL }
 710                 },
 711                 { &hf_lapsat_fragment_multiple_tails,
 712                   { "Message has multiple tail fragments", "lapsat.fragment.multiple_tails",
 713                     FT_BOOLEAN, BASE_NONE, NULL, 0x0,
 714                     "LAPSat Message fragment has multiple tail fragments", HFILL }
 715                 },
 716                 { &hf_lapsat_fragment_too_long_fragment,
 717                   { "Message fragment too long", "lapsat.fragment.too_long_fragment",
 718                     FT_BOOLEAN, BASE_NONE, NULL, 0x0,
 719                     "LAPSat Message fragment data goes beyond the packet end", HFILL }
 720                 },
 721                 { &hf_lapsat_fragment_error,
 722                   { "Message defragmentation error", "lapsat.fragment.error",
 723                     FT_FRAMENUM, BASE_NONE, NULL, 0x00,
 724                     "LAPSat Message defragmentation error due to illegal fragments", HFILL }
 725                 },
 726                 { &hf_lapsat_fragment_count,
 727                   { "Message fragment count", "lapsat.fragment.count",
 728                     FT_UINT32, BASE_DEC, NULL, 0x00,
 729                     NULL, HFILL }
 730                 },
 731                 { &hf_lapsat_reassembled_in,
 732                   { "Reassembled in", "lapsat.reassembled.in",
 733                     FT_FRAMENUM, BASE_NONE, NULL, 0x00,
 734                     "LAPSat Message has been reassembled in this packet.", HFILL }
 735                 },
 736                 { &hf_lapsat_reassembled_length,
 737                   { "Reassembled LAPSat length", "lapsat.reassembled.length",
 738                     FT_UINT32, BASE_DEC, NULL, 0x00,
 739                     "The total length of the reassembled payload", HFILL }
 740                 },
 741         };
 742
 743         static gint *ett[] = {
 744                 &ett_lapsat,
 745                 &ett_lapsat_address,
 746                 &ett_lapsat_control,
 747                 &ett_lapsat_fragment,
 748                 &ett_lapsat_fragments,
 749         };
 750
 751         proto_lapsat = proto_register_protocol("Link Access Procedure, Satellite channel (LAPSat)", "LAPSat", "lapsat");
 752
 753         proto_register_field_array (proto_lapsat, hf, array_length(hf));
 754         proto_register_subtree_array(ett, array_length(ett));
 755
 756         register_dissector("lapsat", dissect_lapsat, proto_lapsat);
 757
 758         lapsat_sapi_dissector_table = register_dissector_table("lapsat.sapi", "LAPSat SAPI", FT_UINT8, BASE_DEC);
 759
 760         register_init_routine (lapsat_defragment_init);
 761 }
 762
 763 void
 764 proto_reg_handoff_lapsat(void)
 765 {
 766         data_handle = find_dissector("data");
 767 }