epan/dissectors/packet-bt-tracker.c

   1 /* packet-bt-tracker.c
   2  * Routines for BitTorrent Tracker over UDP dissection
   3  * Copyright 2023, Ivan Nardi <nardi.ivan@gmail.com>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1999 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include "config.h"
  13
  14 #include <epan/packet.h>
  15 #include <epan/conversation.h>
  16 #include <epan/to_str.h>
  17 #include <epan/prefs.h>
  18 #include <epan/unit_strings.h>
  19
  20 void proto_register_bt_tracker(void);
  21 void proto_reg_handoff_bt_tracker(void);
  22
  23 /* Specifications:
  24  * https://www.bittorrent.org/beps/bep_0015.html BEP 15 UDP Tracker Protocol for BitTorrent
  25  * https://www.bittorrent.org/beps/bep_0041.html BEP 41 UDP Tracker Protocol Extensions
  26  */
  27
  28 enum {
  29   ACTION_CONNECT = 0,
  30   ACTION_ANNOUNCE = 1,
  31   ACTION_SCRAPE = 2,
  32   ACTION_ERROR = 3,
  33 };
  34
  35 enum {
  36   MSG_TYPE_CONNECT_REQUEST,
  37   MSG_TYPE_CONNECT_RESPONSE,
  38   MSG_TYPE_ANNOUNCE_REQUEST,
  39   MSG_TYPE_ANNOUNCE_RESPONSE,
  40   MSG_TYPE_SCRAPE_REQUEST,
  41   MSG_TYPE_SCRAPE_RESPONSE,
  42   MSG_TYPE_ERROR_RESPONSE,
  43
  44   MSG_TYPE_UNKNOWN,
  45 };
  46
  47 static const value_string bt_tracker_msg_type_vals[] = {
  48   { MSG_TYPE_CONNECT_REQUEST,   "Connection Request"  },
  49   { MSG_TYPE_CONNECT_RESPONSE,  "Connection Response"  },
  50   { MSG_TYPE_ANNOUNCE_REQUEST,  "Announce Request"  },
  51   { MSG_TYPE_ANNOUNCE_RESPONSE, "Announce Response"  },
  52   { MSG_TYPE_SCRAPE_REQUEST,    "Scrape Request"  },
  53   { MSG_TYPE_SCRAPE_RESPONSE,   "Scrape Response"  },
  54   { MSG_TYPE_ERROR_RESPONSE,    "Error Response"  },
  55   { 0, NULL }
  56 };
  57
  58 static const value_string bt_tracker_event_vals[] = {
  59   { 0, "None"  },
  60   { 1, "Completed"  },
  61   { 2, "Started"  },
  62   { 3, "Stopped"  },
  63   { 0, NULL }
  64 };
  65
  66 static const value_string bt_tracker_action_vals[] = {
  67   { ACTION_CONNECT,  "Connect"  },
  68   { ACTION_ANNOUNCE, "Announce"   },
  69   { ACTION_SCRAPE,   "Scrape" },
  70   { ACTION_ERROR,    "Error" },
  71   { 0, NULL }
  72 };
  73
  74 enum {
  75   EXT_END_OF_OPTIONS  = 0,
  76   EXT_NOP             = 1,
  77   EXT_URLDATA         = 2,
  78   EXT_MAX
  79 };
  80
  81 static const value_string bt_tracker_extension_type_vals[] = {
  82   { EXT_END_OF_OPTIONS, "End of Options" },
  83   { EXT_NOP,            "NOP" },
  84   { EXT_URLDATA,        "URL Data" },
  85   { 0, NULL }
  86 };
  87
  88 static int proto_bt_tracker;
  89 static dissector_handle_t bt_tracker_handle;
  90
  91 static int hf_bt_tracker_msg_type;
  92 static int hf_bt_tracker_protocol_id;
  93 static int hf_bt_tracker_action;
  94 static int hf_bt_tracker_transaction_id;
  95 static int hf_bt_tracker_connection_id;
  96 static int hf_bt_tracker_info_hash;
  97 static int hf_bt_tracker_peer_id;
  98 static int hf_bt_tracker_downloaded;
  99 static int hf_bt_tracker_left;
 100 static int hf_bt_tracker_uploaded;
 101 static int hf_bt_tracker_event;
 102 static int hf_bt_tracker_ip_address;
 103 static int hf_bt_tracker_key;
 104 static int hf_bt_tracker_num_want;
 105 static int hf_bt_tracker_port;
 106 static int hf_bt_tracker_interval;
 107 static int hf_bt_tracker_leechers;
 108 static int hf_bt_tracker_seeders;
 109 static int hf_bt_tracker_trackers;
 110 static int hf_bt_tracker_tracker;
 111 static int hf_bt_tracker_tr_ip;
 112 static int hf_bt_tracker_tr_ip6;
 113 static int hf_bt_tracker_tr_port;
 114 static int hf_bt_tracker_completed;
 115 static int hf_bt_tracker_error_msg;
 116 static int hf_bt_tracker_extension;
 117 static int hf_bt_tracker_extension_type;
 118 static int hf_bt_tracker_extension_len;
 119 static int hf_bt_tracker_extension_unknown;
 120 static int hf_bt_tracker_extension_urldata;
 121
 122 static int ett_bt_tracker;
 123 static int ett_bt_tracker_trackers;
 124 static int ett_bt_tracker_extension;
 125
 126 #define MAGIC_CONSTANT 0x41727101980
 127
 128 static unsigned
 129 get_message_type(tvbuff_t *tvb)
 130 {
 131   if (tvb_get_ntoh64(tvb, 0) == MAGIC_CONSTANT &&
 132       tvb_get_ntohl(tvb, 8) == ACTION_CONNECT)
 133     return MSG_TYPE_CONNECT_REQUEST;
 134   if (tvb_get_ntohl(tvb, 0) == ACTION_CONNECT)
 135     return MSG_TYPE_CONNECT_RESPONSE;
 136   if (tvb_get_ntohl(tvb, 8) == ACTION_ANNOUNCE)
 137     return MSG_TYPE_ANNOUNCE_REQUEST;
 138   if (tvb_get_ntohl(tvb, 0) == ACTION_ANNOUNCE)
 139     return MSG_TYPE_ANNOUNCE_RESPONSE;
 140   if (tvb_get_ntohl(tvb, 8) == ACTION_SCRAPE)
 141     return MSG_TYPE_SCRAPE_REQUEST;
 142   if (tvb_get_ntohl(tvb, 0) == ACTION_SCRAPE)
 143     return MSG_TYPE_SCRAPE_RESPONSE;
 144   if (tvb_get_ntohl(tvb, 0) == ACTION_ERROR)
 145     return MSG_TYPE_ERROR_RESPONSE;
 146
 147   return MSG_TYPE_UNKNOWN;
 148 }
 149
 150 static bool
 151 is_ipv4_format(packet_info *pinfo)
 152 {
 153   wmem_list_frame_t *cur;
 154   int cur_proto;
 155   const char *cur_name;
 156
 157   /* Format of Announce Response message depends on IPv4 vs IPv6
 158      "Which format is used is determined by the address family of the underlying UDP packet.
 159       I.e. packets from a v4 address use the v4 format, those from a v6 address use the v6 format."
 160      Check the innermost IP layer, to take into account tunnels
 161   */
 162
 163   cur = wmem_list_frame_prev(wmem_list_tail(pinfo->layers));
 164   while (cur != NULL) {
 165     cur_proto = (int)GPOINTER_TO_UINT(wmem_list_frame_data(cur));
 166     cur_name = proto_get_protocol_filter_name(cur_proto);
 167     if (!strcmp(cur_name, "ip"))
 168       return true;
 169     if (!strcmp(cur_name, "ipv6"))
 170       return false;
 171     cur = wmem_list_frame_prev(cur);
 172   }
 173   return true;
 174 }
 175 static int
 176 dissect_bt_tracker_extension(tvbuff_t *tvb, packet_info _U_*pinfo, proto_tree *tree, int offset)
 177 {
 178   proto_item *ti;
 179   proto_tree *ext_tree;
 180   uint8_t extension_type;
 181   uint32_t extension_length;
 182   int32_t tot_length;
 183
 184   while (offset < (int)tvb_reported_length(tvb)) {
 185     extension_type = tvb_get_uint8(tvb, offset);
 186
 187     tot_length = 1;
 188     if (extension_type == EXT_URLDATA) {
 189       tot_length += 1 + tvb_get_uint8(tvb, offset + 1);
 190     } else if (extension_type >= EXT_MAX) {
 191       tot_length = -1;
 192     }
 193
 194     ti = proto_tree_add_none_format(tree, hf_bt_tracker_extension, tvb, offset, tot_length, "Extension: %s", val_to_str_const(extension_type, bt_tracker_extension_type_vals, "Unknown"));
 195     ext_tree = proto_item_add_subtree(ti, ett_bt_tracker_extension);
 196     proto_tree_add_item(ext_tree, hf_bt_tracker_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN);
 197     offset += 1;
 198
 199     switch (extension_type) {
 200       case EXT_END_OF_OPTIONS:
 201         /* Option parsing continues until either the end of the packet is reached, or an EndOfOptions option is encountered, whichever happens first */
 202         return offset;
 203       case EXT_NOP:
 204         /* A special case option that has a fixed-length of one byte. It is not followed by a length field, or associated data.
 205            A NOP has no affect on option parsing. It is used only if optional padding is necessary in the future. */
 206         break;
 207       case EXT_URLDATA:
 208         proto_tree_add_item_ret_uint(ext_tree, hf_bt_tracker_extension_len, tvb, offset, 1, ENC_BIG_ENDIAN, &extension_length);
 209         offset += 1;
 210         proto_tree_add_item(ext_tree, hf_bt_tracker_extension_urldata, tvb, offset, extension_length, ENC_ASCII);
 211         offset += extension_length;
 212         break;
 213       default:
 214         proto_tree_add_item(ext_tree, hf_bt_tracker_extension_unknown, tvb, offset, -1, ENC_NA);
 215         return offset;
 216     }
 217   }
 218   return offset;
 219 }
 220
 221 static int
 222 dissect_bt_tracker_msg(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, unsigned msg_type)
 223 {
 224   unsigned node_index = 0;
 225   int stride_length;
 226   proto_item *ti;
 227   proto_tree *sub_tree;
 228   bool is_ipv6;
 229
 230   ti = proto_tree_add_uint(tree, hf_bt_tracker_msg_type, tvb, 0, 0, msg_type);
 231   proto_item_set_generated(ti);
 232
 233   switch (msg_type) {
 234   case MSG_TYPE_CONNECT_REQUEST:
 235     proto_tree_add_item(tree, hf_bt_tracker_protocol_id, tvb, offset, 8, ENC_BIG_ENDIAN);
 236     offset += 8;
 237     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 238     offset += 4;
 239     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 240     offset += 4;
 241     break;
 242
 243   case MSG_TYPE_CONNECT_RESPONSE:
 244     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 245     offset += 4;
 246     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 247     offset += 4;
 248     proto_tree_add_item(tree, hf_bt_tracker_connection_id, tvb, offset, 8, ENC_BIG_ENDIAN);
 249     offset += 8;
 250     break;
 251
 252   case MSG_TYPE_ANNOUNCE_REQUEST:
 253     proto_tree_add_item(tree, hf_bt_tracker_connection_id, tvb, offset, 8, ENC_BIG_ENDIAN);
 254     offset += 8;
 255     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 256     offset += 4;
 257     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 258     offset += 4;
 259     proto_tree_add_item(tree, hf_bt_tracker_info_hash, tvb, offset, 20, ENC_NA);
 260     offset += 20;
 261     proto_tree_add_item(tree, hf_bt_tracker_peer_id, tvb, offset, 20, ENC_NA);
 262     offset += 20;
 263     proto_tree_add_item(tree, hf_bt_tracker_downloaded, tvb, offset, 8, ENC_BIG_ENDIAN);
 264     offset += 8;
 265     proto_tree_add_item(tree, hf_bt_tracker_left, tvb, offset, 8, ENC_BIG_ENDIAN);
 266     offset += 8;
 267     proto_tree_add_item(tree, hf_bt_tracker_uploaded, tvb, offset, 8, ENC_BIG_ENDIAN);
 268     offset += 8;
 269     proto_tree_add_item(tree, hf_bt_tracker_event, tvb, offset, 4, ENC_BIG_ENDIAN);
 270     offset += 4;
 271     proto_tree_add_item(tree, hf_bt_tracker_ip_address, tvb, offset, 4, ENC_BIG_ENDIAN);
 272     offset += 4;
 273     proto_tree_add_item(tree, hf_bt_tracker_key, tvb, offset, 4, ENC_BIG_ENDIAN);
 274     offset += 4;
 275     proto_tree_add_item(tree, hf_bt_tracker_num_want, tvb, offset, 4, ENC_BIG_ENDIAN);
 276     offset += 4;
 277     proto_tree_add_item(tree, hf_bt_tracker_port, tvb, offset, 2, ENC_BIG_ENDIAN);
 278     offset += 2;
 279
 280     offset = dissect_bt_tracker_extension(tvb, pinfo, tree, offset);
 281     break;
 282
 283   case MSG_TYPE_ANNOUNCE_RESPONSE:
 284     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 285     offset += 4;
 286     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 287     offset += 4;
 288     proto_tree_add_item(tree, hf_bt_tracker_interval, tvb, offset, 4, ENC_BIG_ENDIAN);
 289     offset += 4;
 290     proto_tree_add_item(tree, hf_bt_tracker_leechers, tvb, offset, 4, ENC_BIG_ENDIAN);
 291     offset += 4;
 292     proto_tree_add_item(tree, hf_bt_tracker_seeders, tvb, offset, 4, ENC_BIG_ENDIAN);
 293     offset += 4;
 294
 295     if (tvb_captured_length_remaining(tvb, offset) > 0)
 296     {
 297       stride_length = 6;
 298       is_ipv6 = !is_ipv4_format(pinfo);
 299       if (is_ipv6)
 300         stride_length = 18;
 301       ti = proto_tree_add_item(tree, hf_bt_tracker_trackers, tvb, offset, -1, ENC_NA);
 302       sub_tree = proto_item_add_subtree(ti, ett_bt_tracker_trackers);
 303
 304       while (tvb_captured_length_remaining(tvb, offset) >= stride_length)
 305       {
 306         proto_item *node_ti;
 307         proto_tree *node_tree;
 308
 309         node_index += 1;
 310
 311         node_ti = proto_tree_add_item(sub_tree, hf_bt_tracker_tracker, tvb, offset, stride_length, ENC_NA);
 312         proto_item_append_text(node_ti, " %d", node_index);
 313         node_tree = proto_item_add_subtree(node_ti, ett_bt_tracker_trackers);
 314
 315         if (is_ipv6)
 316         {
 317           proto_tree_add_item( node_tree, hf_bt_tracker_tr_ip6, tvb, offset, 16, ENC_NA);
 318           proto_item_append_text(node_ti, ", IPv6/Port: [%s]", tvb_ip6_to_str(pinfo->pool, tvb, offset));
 319
 320           proto_tree_add_item( node_tree, hf_bt_tracker_tr_port, tvb, offset + 16, 2, ENC_BIG_ENDIAN);
 321           proto_item_append_text(node_ti, ":%u", tvb_get_ntohs( tvb, offset + 16 ));
 322         }
 323         else
 324         {
 325           proto_tree_add_item( node_tree, hf_bt_tracker_tr_ip, tvb, offset, 4, ENC_BIG_ENDIAN);
 326           proto_item_append_text(node_ti, ", IPv4/Port: %s", tvb_ip_to_str(pinfo->pool, tvb, offset));
 327
 328           proto_tree_add_item( node_tree, hf_bt_tracker_tr_port, tvb, offset + 4, 2, ENC_BIG_ENDIAN);
 329           proto_item_append_text(node_ti, ":%u", tvb_get_ntohs( tvb, offset + 4 ));
 330         }
 331
 332         offset += stride_length;
 333       }
 334       proto_item_set_text(ti, "Trackers: %d trackers", node_index);
 335       col_append_fstr(pinfo->cinfo, COL_INFO, ": %d trackers", node_index);
 336     }
 337
 338     break;
 339
 340   case MSG_TYPE_SCRAPE_REQUEST:
 341     proto_tree_add_item(tree, hf_bt_tracker_connection_id, tvb, offset, 8, ENC_BIG_ENDIAN);
 342     offset += 8;
 343     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 344     offset += 4;
 345     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 346     offset += 4;
 347
 348     while (tvb_captured_length_remaining(tvb, offset) >= 20)
 349     {
 350       proto_tree_add_item(tree, hf_bt_tracker_info_hash, tvb, offset, 20, ENC_NA);
 351       offset += 20;
 352     }
 353     break;
 354
 355   case MSG_TYPE_SCRAPE_RESPONSE:
 356     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 357     offset += 4;
 358     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 359     offset += 4;
 360
 361     while (tvb_captured_length_remaining(tvb, offset) >= 12)
 362     {
 363       proto_tree_add_item(tree, hf_bt_tracker_seeders, tvb, offset, 4, ENC_BIG_ENDIAN);
 364       offset += 4;
 365       proto_tree_add_item(tree, hf_bt_tracker_completed, tvb, offset, 4, ENC_BIG_ENDIAN);
 366       offset += 4;
 367       proto_tree_add_item(tree, hf_bt_tracker_leechers, tvb, offset, 4, ENC_BIG_ENDIAN);
 368       offset += 4;
 369     }
 370
 371     break;
 372
 373   case MSG_TYPE_ERROR_RESPONSE:
 374     proto_tree_add_item(tree, hf_bt_tracker_action, tvb, offset, 4, ENC_BIG_ENDIAN);
 375     offset += 4;
 376     proto_tree_add_item(tree, hf_bt_tracker_transaction_id, tvb, offset, 4, ENC_BIG_ENDIAN);
 377     offset += 4;
 378     proto_tree_add_item(tree, hf_bt_tracker_error_msg, tvb, offset, -1, ENC_ASCII);
 379     offset = tvb_captured_length(tvb);
 380     break;
 381
 382   }
 383
 384   return offset;
 385
 386 }
 387 static int
 388 dissect_bt_tracker(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 389 {
 390   unsigned msg_type;
 391   proto_item *ti;
 392   proto_tree *sub_tree;
 393
 394   col_set_str(pinfo->cinfo, COL_PROTOCOL, "BT-Tracker");
 395   col_clear(pinfo->cinfo, COL_INFO);
 396
 397   msg_type = get_message_type(tvb);
 398
 399   col_append_str(pinfo->cinfo, COL_INFO, val_to_str_const(msg_type, bt_tracker_msg_type_vals, " Unknown Msg Type"));
 400
 401   ti = proto_tree_add_item(tree, proto_bt_tracker, tvb, 0, -1, ENC_NA);
 402   sub_tree = proto_item_add_subtree(ti, ett_bt_tracker);
 403
 404   return dissect_bt_tracker_msg(tvb, pinfo, sub_tree, 0, msg_type);
 405 }
 406
 407
 408 static bool
 409 dissect_bt_tracker_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 410 {
 411   conversation_t *conversation;
 412
 413   /* Look for a Connect Request */
 414   if (tvb_captured_length_remaining(tvb, 0) < 16)
 415     return false;
 416   if (tvb_get_ntoh64(tvb, 0) != MAGIC_CONSTANT)
 417     return false;
 418   if (tvb_get_ntohl(tvb, 8) != ACTION_CONNECT)
 419     return false;
 420
 421   conversation = find_or_create_conversation(pinfo);
 422   conversation_set_dissector_from_frame_number(conversation, pinfo->num, bt_tracker_handle);
 423
 424   dissect_bt_tracker(tvb, pinfo, tree, data);
 425   return true;
 426 }
 427
 428 void
 429 proto_register_bt_tracker(void)
 430 {
 431   static hf_register_info hf[] = {
 432     { &hf_bt_tracker_protocol_id,
 433       { "Protocol", "bt-tracker.proto_id",
 434       FT_UINT64, BASE_HEX, NULL, 0x00,
 435       NULL, HFILL }
 436     },
 437     { &hf_bt_tracker_action,
 438       { "Action", "bt-tracker.action",
 439       FT_UINT32, BASE_DEC, VALS(bt_tracker_action_vals), 0x0,
 440       NULL, HFILL }
 441     },
 442     { &hf_bt_tracker_transaction_id,
 443       { "Transaction Id", "bt-tracker.transaction_id",
 444       FT_UINT32, BASE_DEC, NULL, 0x00,
 445       NULL, HFILL }
 446     },
 447     { &hf_bt_tracker_connection_id,
 448       { "Connection Id", "bt-tracker.connection_id",
 449       FT_UINT64, BASE_DEC, NULL, 0x00,
 450       NULL, HFILL }
 451     },
 452     { &hf_bt_tracker_msg_type,
 453       { "Message Type", "bt-tracker.msg_type",
 454       FT_UINT8, BASE_DEC, VALS(bt_tracker_msg_type_vals), 0x0,
 455       NULL, HFILL }
 456     },
 457     { &hf_bt_tracker_info_hash,
 458       { "Info Hash", "bt-tracker.info_hash",
 459       FT_BYTES, BASE_NONE, NULL, 0x00,
 460       NULL, HFILL }
 461     },
 462     { &hf_bt_tracker_peer_id,
 463       { "Peer Id", "bt-tracker.peer_id",
 464       FT_BYTES, BASE_NONE, NULL, 0x00,
 465       NULL, HFILL }
 466     },
 467     { &hf_bt_tracker_downloaded,
 468       { "Downloaded", "bt-tracker.downloaded",
 469       FT_UINT64, BASE_DEC, NULL, 0x00,
 470       NULL, HFILL }
 471     },
 472     { &hf_bt_tracker_left,
 473       { "Left", "bt-tracker.left",
 474       FT_UINT64, BASE_DEC, NULL, 0x00,
 475       NULL, HFILL }
 476     },
 477     { &hf_bt_tracker_uploaded,
 478       { "Uploaded", "bt-tracker.uploaded",
 479       FT_UINT64, BASE_DEC, NULL, 0x00,
 480       NULL, HFILL }
 481     },
 482     { &hf_bt_tracker_event,
 483       { "Event", "bt-tracker.event",
 484       FT_UINT32, BASE_DEC, VALS(bt_tracker_event_vals), 0x00,
 485       NULL, HFILL }
 486     },
 487     { &hf_bt_tracker_ip_address,
 488       { "IP Address", "bt-tracker.ip_address",
 489       FT_IPv4, BASE_NONE, NULL, 0x00,
 490       NULL, HFILL }
 491     },
 492     { &hf_bt_tracker_key,
 493       { "Key", "bt-tracker.key",
 494       FT_UINT32, BASE_DEC, NULL, 0x00,
 495       NULL, HFILL }
 496     },
 497     { &hf_bt_tracker_num_want,
 498       { "Num Want", "bt-tracker.num_want",
 499       FT_INT32, BASE_DEC, NULL, 0x00,
 500       NULL, HFILL }
 501     },
 502     { &hf_bt_tracker_port,
 503       { "Port", "bt-tracker.port",
 504       FT_UINT16, BASE_DEC, NULL, 0x00,
 505       NULL, HFILL }
 506     },
 507     { &hf_bt_tracker_interval,
 508       { "Interval", "bt-tracker.interval",
 509       FT_INT32, BASE_DEC, NULL, 0x00,
 510       NULL, HFILL }
 511     },
 512     { &hf_bt_tracker_leechers,
 513       { "Leechers", "bt-tracker.leechers",
 514       FT_INT32, BASE_DEC, NULL, 0x00,
 515       NULL, HFILL }
 516     },
 517     { &hf_bt_tracker_seeders,
 518       { "Seeders", "bt-tracker.seeders",
 519       FT_INT32, BASE_DEC, NULL, 0x00,
 520       NULL, HFILL }
 521     },
 522     { &hf_bt_tracker_trackers,
 523       { "Trackers", "bt-tracker.trackers",
 524       FT_NONE, BASE_NONE, NULL, 0x0,
 525       NULL, HFILL }
 526     },
 527     { &hf_bt_tracker_tracker,
 528       { "Tracker", "bt-tracker.tracker",
 529       FT_NONE, BASE_NONE, NULL, 0x0,
 530       NULL, HFILL }
 531     },
 532     { &hf_bt_tracker_tr_ip,
 533       { "IP", "bt-tracker.tracker.ip",
 534       FT_IPv4, BASE_NONE, NULL, 0x00,
 535       NULL, HFILL }
 536     },
 537     { &hf_bt_tracker_tr_ip6,
 538       { "IPv6", "bt-tracker.tracker.ip6",
 539       FT_IPv6, BASE_NONE, NULL, 0x00,
 540       NULL, HFILL }
 541     },
 542     { &hf_bt_tracker_tr_port,
 543       { "(TCP) Port", "bt-tracker.tracker.port",
 544       FT_UINT16, BASE_DEC, NULL, 0x00,
 545       NULL, HFILL }
 546     },
 547     { &hf_bt_tracker_completed,
 548       { "Completed", "bt-tracker.completed",
 549       FT_INT32, BASE_DEC, NULL, 0x00,
 550       NULL, HFILL }
 551     },
 552     { &hf_bt_tracker_error_msg,
 553       { "Error message", "bt-tracker.error_msg",
 554       FT_STRING, BASE_NONE, NULL, 0x00,
 555       NULL, HFILL }
 556     },
 557     { &hf_bt_tracker_extension,
 558       { "Extension", "bt-tracker.extension",
 559       FT_NONE, BASE_NONE, NULL, 0x0,
 560       NULL, HFILL }
 561     },
 562     { &hf_bt_tracker_extension_type,
 563       { "Extension Type", "bt-tracker.extension_type",
 564       FT_UINT8, BASE_HEX, VALS(bt_tracker_extension_type_vals), 0x0,
 565       NULL, HFILL }
 566     },
 567     { &hf_bt_tracker_extension_len,
 568       { "Extension Length", "bt-tracker.extension_len",
 569       FT_UINT8, BASE_DEC|BASE_UNIT_STRING, UNS(&units_byte_bytes), 0x0,
 570       NULL, HFILL }
 571     },
 572     { &hf_bt_tracker_extension_unknown,
 573       { "Extension Unknown", "bt-tracker.extension_unknown",
 574       FT_BYTES, BASE_NONE, NULL, 0x0,
 575       NULL, HFILL }
 576     },
 577     { &hf_bt_tracker_extension_urldata,
 578       { "URL Data", "bt-tracker.extension.urldata",
 579       FT_STRING, BASE_NONE, NULL, 0x00,
 580       NULL, HFILL }
 581     },
 582   };
 583
 584   /* Setup protocol subtree array */
 585   static int *ett[] = { &ett_bt_tracker, &ett_bt_tracker_trackers, &ett_bt_tracker_extension};
 586   module_t *bt_tracker_module;
 587
 588   /* Register protocol */
 589   proto_bt_tracker = proto_register_protocol ("BitTorrent Tracker", "BT-Tracker", "bt-tracker");
 590
 591   bt_tracker_module = prefs_register_protocol(proto_bt_tracker, NULL);
 592   prefs_register_obsolete_preference(bt_tracker_module, "enable");
 593
 594   proto_register_field_array(proto_bt_tracker, hf, array_length(hf));
 595   proto_register_subtree_array(ett, array_length(ett));
 596 }
 597
 598 void
 599 proto_reg_handoff_bt_tracker(void)
 600 {
 601   heur_dissector_add("udp", dissect_bt_tracker_heur, "BitTorrent Tracker over UDP", "bt_tracker_udp", proto_bt_tracker, HEURISTIC_ENABLE);
 602
 603   bt_tracker_handle = create_dissector_handle(dissect_bt_tracker, proto_bt_tracker);
 604   dissector_add_for_decode_as_with_preference("udp.port", bt_tracker_handle);
 605 }