epan/dissectors/packet-sscop.c

   1 /* packet-sscop.c
   2  * Routines for SSCOP (Q.2110, Q.SAAL) frame disassembly
   3  * Guy Harris <guy@alum.mit.edu>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998
   8  *
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <epan/packet.h>
  16 #include <epan/prefs.h>
  17 #include <epan/proto_data.h>
  18
  19 #include <wiretap/wtap.h>
  20 #include "packet-sscop.h"
  21
  22 void proto_register_sscop(void);
  23 void proto_reg_handoff_sscop(void);
  24
  25 int proto_sscop;
  26
  27 static int hf_sscop_type;
  28 static int hf_sscop_sq;
  29 static int hf_sscop_mr;
  30 static int hf_sscop_s;
  31 static int hf_sscop_ps;
  32 static int hf_sscop_r;
  33 static int hf_sscop_stat_s;
  34 static int hf_sscop_pad_length;
  35 static int hf_sscop_source;
  36 /* static int hf_sscop_stat_count; */
  37
  38 static int ett_sscop;
  39 static int ett_stat;
  40
  41 static dissector_handle_t q2931_handle;
  42 static dissector_handle_t data_handle;
  43 static dissector_handle_t sscf_nni_handle;
  44 static dissector_handle_t alcap_handle;
  45 static dissector_handle_t nbap_handle;
  46
  47 static dissector_handle_t sscop_handle;
  48
  49
  50 static const enum_val_t sscop_payload_dissector_options[] = {
  51   { "data",     "Data (no further dissection)", DATA_DISSECTOR },
  52   { "Q.2931",   "Q.2931",                       Q2931_DISSECTOR },
  53   { "SSCF-NNI", "SSCF-NNI (MTP3-b)",            SSCF_NNI_DISSECTOR },
  54   { "ALCAP",    "ALCAP",                        ALCAP_DISSECTOR },
  55   { "NBAP",     "NBAP",                         NBAP_DISSECTOR },
  56   { NULL,       NULL,                           0 }
  57 };
  58
  59 static unsigned sscop_payload_dissector = Q2931_DISSECTOR;
  60 static dissector_handle_t default_handle;
  61
  62 static sscop_info_t sscop_info;
  63 /*
  64  * See
  65  *
  66  *   http://web.archive.org/web/20150408122122/http://www.protocols.com/pbook/atmsig.htm
  67  *
  68  * for some information on SSCOP, although, alas, not the actual PDU
  69  * type values - those I got from the FreeBSD 3.2 ATM code.
  70  */
  71
  72 /*
  73  * SSCOP PDU types.
  74  */
  75 #define SSCOP_TYPE_MASK 0x0f
  76
  77 #define SSCOP_BGN       0x01    /* Begin */
  78 #define SSCOP_BGAK      0x02    /* Begin Acknowledge */
  79 #define SSCOP_END       0x03    /* End */
  80 #define SSCOP_ENDAK     0x04    /* End Acknowledge */
  81 #define SSCOP_RS        0x05    /* Resynchronization */
  82 #define SSCOP_RSAK      0x06    /* Resynchronization Acknowledge */
  83 #define SSCOP_BGREJ     0x07    /* Begin Reject */
  84 #define SSCOP_SD        0x08    /* Sequenced Data */
  85 #if 0
  86 #define SSCOP_SDP       0x09    /* Sequenced Data with Poll */
  87 #endif
  88 #define SSCOP_ER        0x09    /* Error Recovery */
  89 #define SSCOP_POLL      0x0a    /* Status Request */
  90 #define SSCOP_STAT      0x0b    /* Solicited Status Response */
  91 #define SSCOP_USTAT     0x0c    /* Unsolicited Status Response */
  92 #define SSCOP_UD        0x0d    /* Unnumbered Data */
  93 #define SSCOP_MD        0x0e    /* Management Data */
  94 #define SSCOP_ERAK      0x0f    /* Error Acknowledge */
  95
  96 #define SSCOP_S         0x10    /* Source bit in End PDU */
  97
  98 /*
  99  * XXX - how to distinguish SDP from ER?
 100  */
 101 static const value_string sscop_type_vals[] = {
 102   { SSCOP_BGN,   "Begin" },
 103   { SSCOP_BGAK,  "Begin Acknowledge" },
 104   { SSCOP_END,   "End" },
 105   { SSCOP_ENDAK, "End Acknowledge" },
 106   { SSCOP_RS,    "Resynchronization" },
 107   { SSCOP_RSAK,  "Resynchronization Acknowledge" },
 108   { SSCOP_BGREJ, "Begin Reject" },
 109   { SSCOP_SD,    "Sequenced Data" },
 110 #if 0
 111   { SSCOP_SDP,   "Sequenced Data with Poll" },
 112 #endif
 113   { SSCOP_ER,    "Error Recovery" },
 114   { SSCOP_POLL,  "Status Request" },
 115   { SSCOP_STAT,  "Solicited Status Response" },
 116   { SSCOP_USTAT, "Unsolicited Status Response" },
 117   { SSCOP_UD,    "Unnumbered Data" },
 118   { SSCOP_MD,    "Management Data" },
 119   { SSCOP_ERAK,  "Error Acknowledge" },
 120   { 0,            NULL }
 121 };
 122 static value_string_ext sscop_type_vals_ext = VALUE_STRING_EXT_INIT(sscop_type_vals);
 123
 124 /*
 125  * The SSCOP "header" is a trailer, so the "offsets" are computed based
 126  * on the length of the packet.
 127  */
 128
 129 /*
 130  * PDU type.
 131  */
 132 #define SSCOP_PDU_TYPE  (reported_length - 4)   /* single byte */
 133
 134 /*
 135  * Begin PDU, Begin Acknowledge PDU (no N(SQ) in it), Resynchronization
 136  * PDU, Resynchronization Acknowledge PDU (no N(SQ) in it in Q.SAAL),
 137  * Error Recovery PDU, Error Recovery Acknoledge PDU (no N(SQ) in it).
 138  */
 139 #define SSCOP_N_SQ      (reported_length - 5)   /* One byte */
 140 #define SSCOP_N_MR      (reported_length - 4)   /* lower 3 bytes thereof */
 141
 142 /*
 143  * Sequenced Data PDU (no N(PS) in it), Sequenced Data with Poll PDU,
 144  * Poll PDU.
 145  */
 146 #define SSCOP_N_PS      (reported_length - 8)   /* lower 3 bytes thereof */
 147 #define SSCOP_N_S       (reported_length - 4)   /* lower 3 bytes thereof */
 148
 149 /*
 150  * Solicited Status PDU, Unsolicited Status PDU (no N(PS) in it).
 151  */
 152 #define SSCOP_SS_N_PS   (reported_length - 12)  /* lower 3 bytes thereof */
 153 #define SSCOP_SS_N_MR   (reported_length - 8)   /* lower 3 bytes thereof */
 154 #define SSCOP_SS_N_R    (reported_length - 4)   /* lower 3 bytes thereof */
 155
 156 static void dissect_stat_list(proto_tree *tree, tvbuff_t *tvb,unsigned h) {
 157   int n,i;
 158
 159   if ((n = (tvb_reported_length(tvb))/4 - h)) {
 160     tree = proto_tree_add_subtree(tree,tvb,0,n*4,ett_stat,NULL,"SD List");
 161
 162     for (i = 0; i < n; i++) {
 163       proto_tree_add_item(tree, hf_sscop_stat_s, tvb, i*4 + 1,3,ENC_BIG_ENDIAN);
 164     }
 165   }
 166 }
 167
 168 extern void
 169 dissect_sscop_and_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, dissector_handle_t payload_handle)
 170 {
 171   unsigned reported_length;
 172   proto_item *ti;
 173   proto_tree *sscop_tree = NULL;
 174   uint8_t sscop_pdu_type;
 175   int pdu_len;
 176   int pad_len;
 177   tvbuff_t *next_tvb;
 178
 179   reported_length = tvb_reported_length(tvb);   /* frame length */
 180   sscop_pdu_type = tvb_get_uint8(tvb, SSCOP_PDU_TYPE);
 181   sscop_info.type = sscop_pdu_type & SSCOP_TYPE_MASK;
 182
 183   col_set_str(pinfo->cinfo, COL_PROTOCOL, "SSCOP");
 184   col_add_str(pinfo->cinfo, COL_INFO, val_to_str_ext(sscop_info.type, &sscop_type_vals_ext,
 185                                                  "Unknown PDU type (0x%02x)"));
 186
 187   /*
 188    * Find the length of the PDU and, if there's any payload and
 189    * padding, the length of the padding.
 190    */
 191   switch (sscop_info.type) {
 192
 193   case SSCOP_SD:
 194     pad_len = (sscop_pdu_type >> 6) & 0x03;
 195     pdu_len = 4;
 196     break;
 197
 198   case SSCOP_BGN:
 199   case SSCOP_BGAK:
 200   case SSCOP_BGREJ:
 201   case SSCOP_END:
 202   case SSCOP_RS:
 203 #if 0
 204   case SSCOP_SDP:
 205 #endif
 206     pad_len = (sscop_pdu_type >> 6) & 0x03;
 207     sscop_info.payload_len = pdu_len = 8;
 208     break;
 209
 210   case SSCOP_UD:
 211     pad_len = (sscop_pdu_type >> 6) & 0x03;
 212     sscop_info.payload_len = pdu_len = 4;
 213     break;
 214
 215   default:
 216     pad_len = 0;
 217     pdu_len = reported_length;  /* No payload, just SSCOP */
 218     sscop_info.payload_len = 0;
 219     break;
 220   }
 221
 222   if (tree) {
 223     ti = proto_tree_add_protocol_format(tree, proto_sscop, tvb,
 224                                         reported_length - pdu_len,
 225                                         pdu_len, "SSCOP");
 226     sscop_tree = proto_item_add_subtree(ti, ett_sscop);
 227
 228     proto_tree_add_item(sscop_tree, hf_sscop_type, tvb, SSCOP_PDU_TYPE, 1,ENC_BIG_ENDIAN);
 229
 230     switch (sscop_info.type) {
 231
 232     case SSCOP_BGN:
 233     case SSCOP_RS:
 234     case SSCOP_ER:
 235       proto_tree_add_item(sscop_tree, hf_sscop_sq, tvb, SSCOP_N_SQ, 1,ENC_BIG_ENDIAN);
 236       proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
 237       break;
 238
 239     case SSCOP_END:
 240       proto_tree_add_string(sscop_tree, hf_sscop_source, tvb, SSCOP_PDU_TYPE, 1,
 241                                 (sscop_pdu_type & SSCOP_S) ? "SSCOP" : "User");
 242       break;
 243
 244     case SSCOP_BGAK:
 245     case SSCOP_RSAK:
 246       proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
 247       break;
 248
 249     case SSCOP_ERAK:
 250       proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
 251       break;
 252
 253     case SSCOP_SD:
 254       proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3, ENC_BIG_ENDIAN);
 255       break;
 256
 257 #if 0
 258     case SSCOP_SDP:
 259 #endif
 260     case SSCOP_POLL:
 261       proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_N_PS + 1, 3,ENC_BIG_ENDIAN);
 262       proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3,ENC_BIG_ENDIAN);
 263       break;
 264
 265     case SSCOP_STAT:
 266       proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_SS_N_PS + 1, 3,ENC_BIG_ENDIAN);
 267       proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, ENC_BIG_ENDIAN);
 268       proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,ENC_BIG_ENDIAN);
 269       dissect_stat_list(sscop_tree,tvb,3);
 270       break;
 271
 272     case SSCOP_USTAT:
 273       proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, ENC_BIG_ENDIAN);
 274       proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,ENC_BIG_ENDIAN);
 275       dissect_stat_list(sscop_tree,tvb,2);
 276       break;
 277     }
 278   }
 279
 280   /*
 281    * Dissect the payload, if any.
 282    *
 283    * XXX - what about a Management Data PDU?
 284    */
 285   switch (sscop_info.type) {
 286
 287   case SSCOP_SD:
 288   case SSCOP_UD:
 289   case SSCOP_BGN:
 290   case SSCOP_BGAK:
 291   case SSCOP_BGREJ:
 292   case SSCOP_END:
 293   case SSCOP_RS:
 294 #if 0
 295   case SSCOP_SDP:
 296 #endif
 297     if (tree) {
 298       proto_tree_add_uint(sscop_tree, hf_sscop_pad_length, tvb, SSCOP_PDU_TYPE, 1, pad_len);
 299     }
 300
 301     /*
 302      * Compute length of data in PDU - subtract the trailer length
 303      * and the pad length from the reported length.
 304      */
 305     reported_length -= (pdu_len + pad_len);
 306
 307     if (reported_length != 0) {
 308       /*
 309        * We know that we have all of the payload, because we know we have
 310        * at least 4 bytes of data after the payload, i.e. the SSCOP trailer.
 311        * Therefore, we know that the captured length of the payload is
 312        * equal to the length of the payload.
 313        */
 314       next_tvb = tvb_new_subset_length(tvb, 0, reported_length);
 315       if (sscop_info.type == SSCOP_SD)
 316       {
 317         call_dissector(payload_handle, next_tvb, pinfo, tree);
 318       }
 319     break;
 320   }
 321 }
 322 }
 323
 324 static int dissect_sscop(tvbuff_t* tvb, packet_info* pinfo,proto_tree* tree, void* data _U_)
 325 {
 326   struct _sscop_payload_info  *p_sscop_info;
 327   dissector_handle_t subdissector;
 328
 329   /* Look for packet info for subdissector information */
 330   p_sscop_info = (struct _sscop_payload_info *)p_get_proto_data(wmem_file_scope(), pinfo, proto_sscop, 0);
 331
 332   if ( p_sscop_info
 333        && ( subdissector = p_sscop_info->subdissector )
 334        && ( subdissector == data_handle
 335             || subdissector == q2931_handle
 336             || subdissector == sscf_nni_handle
 337             || subdissector == alcap_handle
 338             || subdissector == nbap_handle) )
 339     dissect_sscop_and_payload(tvb,pinfo,tree,subdissector);
 340   else
 341     dissect_sscop_and_payload(tvb,pinfo,tree,default_handle);
 342
 343   return tvb_captured_length(tvb);
 344 }
 345
 346 /* Make sure handles for various protocols are initialized */
 347 static void initialize_handles_once(void) {
 348   static bool initialized = false;
 349   if (!initialized) {
 350     q2931_handle = find_dissector("q2931");
 351     data_handle = find_dissector("data");
 352     sscf_nni_handle = find_dissector("sscf-nni");
 353     alcap_handle = find_dissector("alcap");
 354     nbap_handle = find_dissector("nbap");
 355
 356     initialized = true;
 357   }
 358 }
 359
 360 bool sscop_allowed_subdissector(dissector_handle_t handle)
 361 {
 362   initialize_handles_once();
 363   if (handle == q2931_handle || handle == data_handle
 364       || handle == sscf_nni_handle || handle == alcap_handle
 365       || handle == nbap_handle)
 366     return true;
 367   return false;
 368 }
 369
 370 void
 371 proto_reg_handoff_sscop(void)
 372 {
 373   static bool prefs_initialized = false;
 374
 375   if (!prefs_initialized) {
 376     initialize_handles_once();
 377     dissector_add_uint_range_with_preference("udp.port", "", sscop_handle);
 378     dissector_add_uint("atm.aal5.type", TRAF_SSCOP, sscop_handle);
 379
 380     prefs_initialized = true;
 381   }
 382
 383   switch(sscop_payload_dissector) {
 384   case DATA_DISSECTOR:     default_handle = data_handle;     break;
 385   case Q2931_DISSECTOR:    default_handle = q2931_handle;    break;
 386   case SSCF_NNI_DISSECTOR: default_handle = sscf_nni_handle; break;
 387   case ALCAP_DISSECTOR:    default_handle = alcap_handle;    break;
 388   case NBAP_DISSECTOR:     default_handle = nbap_handle;     break;
 389   }
 390
 391 }
 392
 393 void
 394 proto_register_sscop(void)
 395 {
 396   static hf_register_info hf[] = {
 397     { &hf_sscop_type, { "PDU Type", "sscop.type", FT_UINT8, BASE_HEX|BASE_EXT_STRING, &sscop_type_vals_ext, SSCOP_TYPE_MASK, NULL, HFILL }},
 398     { &hf_sscop_sq, { "N(SQ)", "sscop.sq", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 399     { &hf_sscop_mr, { "N(MR)", "sscop.mr", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 400     { &hf_sscop_s, { "N(S)", "sscop.s", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 401     { &hf_sscop_ps, { "N(PS)", "sscop.ps", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 402     { &hf_sscop_r, { "N(R)", "sscop.r", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 403     { &hf_sscop_stat_s, { "N(S)", "sscop.stat.s", FT_UINT24, BASE_DEC, NULL, 0x0,NULL, HFILL }},
 404     { &hf_sscop_pad_length, { "Pad length", "sscop.pad_length", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
 405     { &hf_sscop_source, { "Source", "sscop.source", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},
 406 #if 0
 407     { &hf_sscop_stat_count, { "Number of NACKed pdus", "sscop.stat.count", FT_UINT32, BASE_DEC, NULL, 0x0,NULL, HFILL }}
 408 #endif
 409   };
 410
 411   static int *ett[] = {
 412     &ett_sscop,
 413     &ett_stat
 414   };
 415
 416   module_t *sscop_module;
 417
 418   proto_sscop = proto_register_protocol("SSCOP", "SSCOP", "sscop");
 419   proto_register_field_array(proto_sscop, hf, array_length(hf));
 420   proto_register_subtree_array(ett, array_length(ett));
 421
 422   sscop_handle = register_dissector("sscop", dissect_sscop, proto_sscop);
 423
 424   sscop_module = prefs_register_protocol(proto_sscop, proto_reg_handoff_sscop);
 425
 426   prefs_register_enum_preference(sscop_module, "payload",
 427                                  "SSCOP payload protocol",
 428                                  "SSCOP payload (dissector to call on SSCOP payload)",
 429                                  (int *)&sscop_payload_dissector,
 430                                  sscop_payload_dissector_options, false);
 431 }
 432
 433 /*
 434  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 435  *
 436  * Local Variables:
 437  * c-basic-offset: 2
 438  * tab-width: 8
 439  * indent-tabs-mode: nil
 440  * End:
 441  *
 442  * ex: set shiftwidth=2 tabstop=8 expandtab:
 443  * :indentSize=2:tabSize=8:noTabs=true:
 444  */