/* packet-bittorrent.c * Routines for bittorrent packet dissection * Copyright (C) 2004 Jelmer Vernooij * * $Id$ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * Copied from packet-pop.c * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #include #include #include #include #include #include #include "packet-tcp.h" /* * See * * http://bittorrent.com/protocol.html * http://wiki.theory.org/BitTorrentSpecification * http://bitconjurer.org/BitTorrent/protocol.html */ #define BITTORRENT_MESSAGE_CHOKE 0 #define BITTORRENT_MESSAGE_UNCHOKE 1 #define BITTORRENT_MESSAGE_INTERESTED 2 #define BITTORRENT_MESSAGE_NOT_INTERESTED 3 #define BITTORRENT_MESSAGE_HAVE 4 #define BITTORRENT_MESSAGE_BITFIELD 5 #define BITTORRENT_MESSAGE_REQUEST 6 #define BITTORRENT_MESSAGE_PIECE 7 #define BITTORRENT_MESSAGE_CANCEL 8 #define BITTORRENT_HEADER_LENGTH 4 static const value_string bittorrent_messages[] = { { BITTORRENT_MESSAGE_CHOKE, "Choke" }, { BITTORRENT_MESSAGE_UNCHOKE, "Unchoke" }, { BITTORRENT_MESSAGE_INTERESTED, "Interested" }, { BITTORRENT_MESSAGE_NOT_INTERESTED, "Not Interested" }, { BITTORRENT_MESSAGE_HAVE, "Have" }, { BITTORRENT_MESSAGE_BITFIELD, "Bitfield" }, { BITTORRENT_MESSAGE_REQUEST, "Request" }, { BITTORRENT_MESSAGE_PIECE, "Piece" }, { BITTORRENT_MESSAGE_CANCEL, "Cancel" }, { 0, NULL } }; static dissector_handle_t dissector_handle; static int proto_bittorrent = -1; static gint hf_bittorrent_field_length = -1; static gint hf_bittorrent_prot_name_len = -1; static gint hf_bittorrent_prot_name = -1; static gint hf_bittorrent_reserved = -1; static gint hf_bittorrent_sha1_hash = -1; static gint hf_bittorrent_peer_id = -1; static gint hf_bittorrent_msg_len = -1; static gint hf_bittorrent_msg_type = -1; static gint hf_bittorrent_bitfield_data = -1; static gint hf_bittorrent_piece_index = -1; static gint hf_bittorrent_piece_begin = -1; static gint hf_bittorrent_piece_length = -1; static gint hf_bittorrent_piece_data = -1; static gint ett_bittorrent = -1; static gint ett_bittorrent_msg = -1; static gint ett_peer_id = -1; static gboolean bittorrent_desegment = TRUE; static gboolean decode_client_information = FALSE; struct client_information { char id[4]; char *name; }; static struct client_information peer_id[] = { {"-AZ", "Azureus"}, {"-BB", "BitBuddy"}, {"-CT", "CTorrent"}, {"-MT", "MoonlightTorrent"}, {"-LT", "libtorrent"}, {"-BX", "Bittorrent X"}, {"-TS", "Torrentstorm"}, {"-TN", "TorrnetDotNET"}, {"-SS", "SwarmScope"}, {"-XT", "XanTorrent"}, {"-BS", "BTSlave"}, {"-ZT", "ZipTorrent"}, {"S", "Shadow's client"}, {"U", "UPnP NAT Bit Torrent"}, {"T", "BitTornado"}, {"A", "ABC"}, {"", NULL} }; static guint get_bittorrent_pdu_length(tvbuff_t *tvb, int offset) { guint8 type; guint32 length; if (tvb_get_guint8(tvb, offset) == 19 && tvb_memeql(tvb, offset + 1, "BitTorrent protocol", 19) == 0) { /* Return the length of a Handshake message */ return 1 + /* pstrlen */ 19 + /* pstr */ 8 + /* reserved */ 20 + /* SHA1 hash of the info key */ 20; /* peer id */ } else { /* Try to validate the length of the message indicated by the header. */ length = tvb_get_ntohl(tvb, offset); if(length == 0) { /* keep-alive - no message ID */ return BITTORRENT_HEADER_LENGTH; } /* Do some sanity checking of the message, if we have the ID byte */ if(tvb_offset_exists(tvb, offset + BITTORRENT_HEADER_LENGTH)) { type = tvb_get_guint8(tvb, offset + BITTORRENT_HEADER_LENGTH); if(type <= BITTORRENT_MESSAGE_CANCEL) { /* This seems to be a valid BitTorrent header with a known type identifier */ return BITTORRENT_HEADER_LENGTH + length; } else { /* The type is not known, so this message cannot be decoded properly by this dissector. We assume it's continuation data from the middle of a message, and just return the remaining length in the tvbuff so the rest of the tvbuff is displayed as continuation data. */ return tvb_length_remaining(tvb, offset); } } else { /* We don't have the type field, so we can't determine whether this is a valid message. For now, we assume it's continuation data from the middle of a message, and just return the remaining length in the tvbuff so the rest of the tvbuff is displayed as continuation data. */ return tvb_length_remaining(tvb, offset); } } } static void dissect_bittorrent_message (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { int offset = 0; proto_tree *mtree; guint8 type = 0; guint32 length; const char *msgtype = NULL; proto_item *ti; if (tvb_bytes_exist(tvb, offset + BITTORRENT_HEADER_LENGTH, 1)) { /* Check for data from the middle of a message. */ type = tvb_get_guint8(tvb, offset + BITTORRENT_HEADER_LENGTH); msgtype = match_strval(type, bittorrent_messages); if (msgtype == NULL) { proto_tree_add_text(tree, tvb, offset, -1, "Continuation data"); if (check_col(pinfo->cinfo, COL_INFO)) { col_add_str(pinfo->cinfo, COL_INFO, "Continuation"); } return; } } length = tvb_get_ntohl(tvb, offset); ti = proto_tree_add_text(tree, tvb, offset, length + BITTORRENT_HEADER_LENGTH, "BitTorrent Message"); mtree = proto_item_add_subtree(ti, ett_bittorrent_msg); /* Keepalive message */ if (length == 0) { proto_tree_add_item(mtree, hf_bittorrent_msg_len, tvb, offset, BITTORRENT_HEADER_LENGTH, FALSE); if (check_col(pinfo->cinfo, COL_INFO)) { col_set_str(pinfo->cinfo, COL_INFO, "BitTorrent KeepAlive message"); } return; } proto_tree_add_item(mtree, hf_bittorrent_msg_len, tvb, offset, BITTORRENT_HEADER_LENGTH, FALSE); offset += BITTORRENT_HEADER_LENGTH; /* If the tvb_bytes_exist() call above returned FALSE, this will throw an exception, so we won't use msgtype or type. */ proto_tree_add_item(mtree, hf_bittorrent_msg_type, tvb, offset, 1, FALSE); if (check_col(pinfo->cinfo, COL_INFO)) { col_add_str(pinfo->cinfo, COL_INFO, msgtype); } offset += 1; length -= 1; switch (type) { case BITTORRENT_MESSAGE_CHOKE: case BITTORRENT_MESSAGE_UNCHOKE: case BITTORRENT_MESSAGE_INTERESTED: case BITTORRENT_MESSAGE_NOT_INTERESTED: /* No payload */ break; case BITTORRENT_MESSAGE_REQUEST: case BITTORRENT_MESSAGE_CANCEL: proto_tree_add_item(mtree, hf_bittorrent_piece_index, tvb, offset, 4, FALSE); offset += 4; proto_tree_add_item(mtree, hf_bittorrent_piece_begin, tvb, offset, 4, FALSE); offset += 4; proto_tree_add_item(mtree, hf_bittorrent_piece_length, tvb, offset, 4, FALSE); break; case BITTORRENT_MESSAGE_HAVE: proto_tree_add_item(mtree, hf_bittorrent_piece_index, tvb, offset, 4, FALSE); break; case BITTORRENT_MESSAGE_BITFIELD: proto_tree_add_item(mtree, hf_bittorrent_bitfield_data, tvb, offset, length, FALSE); break; case BITTORRENT_MESSAGE_PIECE: proto_tree_add_item(mtree, hf_bittorrent_piece_index, tvb, offset, 4, FALSE); offset += 4; length -= 4; proto_tree_add_item(mtree, hf_bittorrent_piece_begin, tvb, offset, 4, FALSE); offset += 4; length -= 4; proto_tree_add_item(mtree, hf_bittorrent_piece_data, tvb, offset, length, FALSE); break; default: break; } } static void dissect_bittorrent_welcome (tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { int offset = 0; int i; char *version; if (check_col(pinfo->cinfo, COL_INFO)) { col_set_str(pinfo->cinfo, COL_INFO, "BitTorrent Handshake"); } proto_tree_add_item(tree, hf_bittorrent_prot_name_len, tvb, offset, 1, FALSE); offset+=1; proto_tree_add_item(tree, hf_bittorrent_prot_name, tvb, offset, 19, FALSE); offset += 19; proto_tree_add_item(tree, hf_bittorrent_reserved, tvb, offset, 8, FALSE); offset += 8; proto_tree_add_item(tree, hf_bittorrent_sha1_hash, tvb, offset, 20, FALSE); offset += 20; proto_tree_add_item(tree, hf_bittorrent_peer_id, tvb, offset, 20, FALSE); if(decode_client_information) { for(i = 0; peer_id[i].id[0] != '\0'; ++i) { if(tvb_memeql(tvb, offset, peer_id[i].id, strlen(peer_id[i].id)) == 0) { /* The version number is 4 numeric characters for the client ids beginning with '-' and 3 characters for the rest. */ version = tvb_get_string(tvb, offset + strlen(peer_id[i].id), (peer_id[i].id[0] == '-') ? 4 : 3); proto_tree_add_text(tree, tvb, offset, 20, "Client is %s v%s", peer_id[i].name, format_text(version, (peer_id[i].id[0] == '-') ? 4 : 3)); g_free(version); break; } } } offset += 20; } static void dissect_bittorrent_tcp_pdu (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_item *ti; if (check_col(pinfo->cinfo, COL_PROTOCOL)) { col_set_str(pinfo->cinfo, COL_PROTOCOL, "BitTorrent"); } if (check_col(pinfo->cinfo, COL_INFO)) { col_set_str(pinfo->cinfo, COL_INFO, "BitTorrent Peer-To-Peer connection"); } ti = proto_tree_add_text(tree, tvb, 0, -1, "BitTorrent"); tree = proto_item_add_subtree(ti, ett_bittorrent); if (tvb_get_guint8(tvb, 0) == 19 && tvb_memeql(tvb, 1, "BitTorrent protocol", 19) == 0) { dissect_bittorrent_welcome(tvb, pinfo, tree); } else { dissect_bittorrent_message(tvb, pinfo, tree); } } static void dissect_bittorrent (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { tcp_dissect_pdus(tvb, pinfo, tree, bittorrent_desegment, BITTORRENT_HEADER_LENGTH, get_bittorrent_pdu_length, dissect_bittorrent_tcp_pdu); } static gboolean test_bittorrent_packet (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { conversation_t *conversation; if (tvb_bytes_exist(tvb, 0, 20) && tvb_get_guint8(tvb, 0) == 19 && tvb_memeql(tvb, 1, "BitTorrent protocol", 19) == 0) { conversation = conversation_new (pinfo->fd->num, &pinfo->src, &pinfo->dst, pinfo->ptype, pinfo->srcport, pinfo->destport, 0); conversation_set_dissector(conversation, dissector_handle); dissect_bittorrent(tvb, pinfo, tree); return TRUE; } return FALSE; } void proto_register_bittorrent(void) { static hf_register_info hf[] = { { &hf_bittorrent_field_length, { "Field Length", "bittorrent.length", FT_UINT32, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_prot_name_len, { "Protocol Name Length", "bittorrent.protocol.name.length", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_prot_name, { "Protocol Name", "bittorrent.protocol.name", FT_STRING, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_reserved, { "Reserved Extension Bytes", "bittorrent.reserved", FT_BYTES, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_sha1_hash, { "SHA1 Hash of info dictionary", "bittorrent.info_hash", FT_BYTES, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_peer_id, { "Peer ID", "bittorrent.peer_id", FT_BYTES, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_msg_len, { "Message Length", "bittorrent.msg.length", FT_UINT32, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_msg_type, { "Message Type", "bittorrent.msg.type", FT_UINT8, BASE_DEC, VALS(bittorrent_messages), 0x0, "", HFILL } }, { &hf_bittorrent_bitfield_data, { "Bitfield data", "bittorrent.msg.bitfield", FT_BYTES, BASE_HEX, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_piece_index, { "Piece index", "bittorrent.piece.index", FT_UINT32, BASE_HEX, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_piece_begin, { "Begin offset of piece", "bittorrent.piece.begin", FT_UINT32, BASE_HEX, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_piece_data, { "Data in a piece", "bittorrent.piece.data", FT_BYTES, BASE_HEX, NULL, 0x0, "", HFILL } }, { &hf_bittorrent_piece_length, { "Piece Length", "bittorrent.piece.length", FT_UINT32, BASE_HEX, NULL, 0x0, "", HFILL } } }; static gint *ett[] = { &ett_bittorrent, &ett_bittorrent_msg, &ett_peer_id }; module_t *bittorrent_module; proto_bittorrent = proto_register_protocol("BitTorrent", "BitTorrent", "bittorrent"); proto_register_field_array(proto_bittorrent, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); bittorrent_module = prefs_register_protocol(proto_bittorrent, NULL); prefs_register_bool_preference(bittorrent_module, "desegment", "Reassemble BitTorrent messages spanning multiple TCP segments", "Whether the BitTorrent dissector should reassemble messages spanning multiple TCP segments." " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.", &bittorrent_desegment); prefs_register_bool_preference(bittorrent_module, "decode_client", "Decode the peer_id of the handshake messages", "Enabling this will tell which BitTorrent client that produced the handshake message", &decode_client_information); } void proto_reg_handoff_bittorrent(void) { dissector_handle = create_dissector_handle(dissect_bittorrent, proto_bittorrent); heur_dissector_add("tcp", test_bittorrent_packet, proto_bittorrent); }