/* packet-bt-utp.c * Routines for BT-UTP dissection * Copyright 2011, Xiao Xiangquan * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1999 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include #include void proto_register_bt_utp(void); void proto_reg_handoff_bt_utp(void); enum { ST_DATA = 0, ST_FIN = 1, ST_STATE = 2, ST_RESET = 3, ST_SYN = 4, ST_NUM_STATES }; /* V0 hdr: "flags"; V1 hdr: "type" */ static const value_string bt_utp_type_vals[] = { { ST_DATA, "Data" }, { ST_FIN, "Fin" }, { ST_STATE, "State" }, { ST_RESET, "Reset" }, { ST_SYN, "Syn" }, { 0, NULL } }; enum { EXT_NO_EXTENSION = 0, EXT_SELECTION_ACKS = 1, EXT_EXTENSION_BITS = 2, EXT_NUM_EXT }; static const value_string bt_utp_extension_type_vals[] = { { EXT_NO_EXTENSION, "No Extension" }, { EXT_SELECTION_ACKS, "Selective ACKs" }, { EXT_EXTENSION_BITS, "Extension bits" }, { 0, NULL } }; static int proto_bt_utp = -1; /* --- "Original" uTP Header ("version 0" ?) -------------- See utp.cpp source code @ https://github.com/bittorrent/libutp -- Fixed Header -- 0 4 8 16 24 32 +-------+-------+---------------+---------------+---------------+ | connection_id | +-------+-------+---------------+---------------+---------------+ | timestamp_seconds | +---------------+---------------+---------------+---------------+ | timestamp_microseconds | +---------------+---------------+---------------+---------------+ | timestamp_difference_microseconds | +---------------+---------------+---------------+---------------+ | wnd_size | ext | flags | seq_nr [ho] | +---------------+---------------+---------------+---------------+ | seq_nr [lo] | ack_nr | +---------------+---------------+---------------+ -- Extension Field(s) -- 0 8 16 +---------------+---------------+---------------+---------------+ | extension | len | bitmask +---------------+---------------+---------------+---------------+ | +---------------+---------------+.... */ /* --- Version 1 Header ---------------- Specifications: BEP-0029 http://www.bittorrent.org/beps/bep_0029.html -- Fixed Header -- Fields Types 0 4 8 16 24 32 +-------+-------+---------------+---------------+---------------+ | type | ver | extension | connection_id | +-------+-------+---------------+---------------+---------------+ | timestamp_microseconds | +---------------+---------------+---------------+---------------+ | timestamp_difference_microseconds | +---------------+---------------+---------------+---------------+ | wnd_size | +---------------+---------------+---------------+---------------+ | seq_nr | ack_nr | +---------------+---------------+---------------+---------------+ -- Extension Field(s) -- 0 8 16 +---------------+---------------+---------------+---------------+ | extension | len | bitmask +---------------+---------------+---------------+---------------+ | +---------------+---------------+.... */ #define V0_FIXED_HDR_SIZE 23 #define V1_FIXED_HDR_SIZE 20 static dissector_handle_t bt_utp_handle; static int hf_bt_utp_ver = -1; static int hf_bt_utp_type = -1; static int hf_bt_utp_flags = -1; static int hf_bt_utp_extension = -1; static int hf_bt_utp_next_extension_type = -1; static int hf_bt_utp_extension_len = -1; static int hf_bt_utp_extension_bitmask = -1; static int hf_bt_utp_extension_unknown = -1; static int hf_bt_utp_connection_id_v0 = -1; static int hf_bt_utp_connection_id_v1 = -1; static int hf_bt_utp_timestamp_sec = -1; static int hf_bt_utp_timestamp_us = -1; static int hf_bt_utp_timestamp_diff_us = -1; static int hf_bt_utp_wnd_size_v0 = -1; static int hf_bt_utp_wnd_size_v1 = -1; static int hf_bt_utp_seq_nr = -1; static int hf_bt_utp_ack_nr = -1; static int hf_bt_utp_data = -1; static gint ett_bt_utp = -1; static gint ett_bt_utp_extension = -1; static gint get_utp_version(tvbuff_t *tvb) { guint8 v0_flags, v0_ext; guint8 v1_ver_type, v1_ext; guint len; /* Simple heuristics inspired by code from utp.cpp */ len = tvb_captured_length(tvb); /* Version 1? */ if (len < V1_FIXED_HDR_SIZE) { return -1; } v1_ver_type = tvb_get_guint8(tvb, 0); v1_ext = tvb_get_guint8(tvb, 1); if (((v1_ver_type & 0x0f) == 1) && ((v1_ver_type>>4) < ST_NUM_STATES) && (v1_ext < EXT_NUM_EXT)) { return 1; } /* Version 0? */ if (len < V0_FIXED_HDR_SIZE) { return -1; } v0_flags = tvb_get_guint8(tvb, 18); v0_ext = tvb_get_guint8(tvb, 17); if ((v0_flags < ST_NUM_STATES) || (v0_ext < EXT_NUM_EXT)) { return 0; } return -1; } static int dissect_utp_header_v0(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, guint8 *extension_type) { /* "Original" (V0) */ proto_tree_add_item(tree, hf_bt_utp_connection_id_v0, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_timestamp_sec, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_timestamp_us, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_timestamp_diff_us, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_wnd_size_v0, tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1; proto_tree_add_item(tree, hf_bt_utp_next_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN); *extension_type = tvb_get_guint8(tvb, offset); offset += 1; proto_tree_add_item(tree, hf_bt_utp_flags, tvb, offset, 1, ENC_BIG_ENDIAN); col_append_fstr(pinfo->cinfo, COL_INFO, " Type: %s", val_to_str(tvb_get_guint8(tvb, offset), bt_utp_type_vals, "Unknown %d")); offset += 1; proto_tree_add_item(tree, hf_bt_utp_seq_nr, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; proto_tree_add_item(tree, hf_bt_utp_ack_nr, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; return offset; } static int dissect_utp_header_v1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, guint8 *extension_type) { /* V1 */ proto_tree_add_item(tree, hf_bt_utp_ver, tvb, offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_bt_utp_type, tvb, offset, 1, ENC_BIG_ENDIAN); col_append_fstr(pinfo->cinfo, COL_INFO, " Type: %s", val_to_str((tvb_get_guint8(tvb, offset) >> 4), bt_utp_type_vals, "Unknown %d")); offset += 1; proto_tree_add_item(tree, hf_bt_utp_next_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN); *extension_type = tvb_get_guint8(tvb, offset); offset += 1; proto_tree_add_item(tree, hf_bt_utp_connection_id_v1, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; proto_tree_add_item(tree, hf_bt_utp_timestamp_us, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_timestamp_diff_us, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_wnd_size_v1, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; proto_tree_add_item(tree, hf_bt_utp_seq_nr, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; proto_tree_add_item(tree, hf_bt_utp_ack_nr, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; return offset; } static int dissect_utp_extension(tvbuff_t *tvb, packet_info _U_*pinfo, proto_tree *tree, int offset, guint8 *extension_type) { proto_item *ti; proto_tree *ext_tree; guint8 extension_length; /* display the extension tree */ while(*extension_type != EXT_NO_EXTENSION && offset < (int)tvb_reported_length(tvb)) { switch(*extension_type){ case EXT_SELECTION_ACKS: /* 1 */ { ti = proto_tree_add_item(tree, hf_bt_utp_extension, tvb, offset, -1, ENC_NA); ext_tree = proto_item_add_subtree(ti, ett_bt_utp_extension); proto_tree_add_item(ext_tree, hf_bt_utp_next_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN); *extension_type = tvb_get_guint8(tvb, offset); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_len, tvb, offset, 1, ENC_BIG_ENDIAN); extension_length = tvb_get_guint8(tvb, offset); proto_item_append_text(ti, " Selection ACKs, Len=%d", extension_length); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_bitmask, tvb, offset, extension_length, ENC_NA); offset += extension_length; proto_item_set_len(ti, 1 + 1 + extension_length); break; } case EXT_EXTENSION_BITS: /* 2 */ { ti = proto_tree_add_item(tree, hf_bt_utp_extension, tvb, offset, -1, ENC_NA); ext_tree = proto_item_add_subtree(ti, ett_bt_utp_extension); proto_tree_add_item(ext_tree, hf_bt_utp_next_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN); *extension_type = tvb_get_guint8(tvb, offset); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_len, tvb, offset, 1, ENC_BIG_ENDIAN); extension_length = tvb_get_guint8(tvb, offset); proto_item_append_text(ti, " Extension Bits, Len=%d", extension_length); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_bitmask, tvb, offset, extension_length, ENC_NA); offset += extension_length; proto_item_set_len(ti, 1 + 1 + extension_length); break; } default: ti = proto_tree_add_item(tree, hf_bt_utp_extension, tvb, offset, -1, ENC_NA); ext_tree = proto_item_add_subtree(ti, ett_bt_utp_extension); proto_tree_add_item(ext_tree, hf_bt_utp_next_extension_type, tvb, offset, 1, ENC_BIG_ENDIAN); *extension_type = tvb_get_guint8(tvb, offset); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_len, tvb, offset, 1, ENC_BIG_ENDIAN); extension_length = tvb_get_guint8(tvb, offset); proto_item_append_text(ti, " Unknown, Len=%d", extension_length); offset += 1; proto_tree_add_item(ext_tree, hf_bt_utp_extension_unknown, tvb, offset, extension_length, ENC_NA); offset += extension_length; proto_item_set_len(ti, 1 + 1 + extension_length); break; } } return offset; } static int dissect_bt_utp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) { gint version; version = get_utp_version(tvb); /* try dissecting */ if (version >= 0) { conversation_t *conversation; guint len_tvb; proto_tree *sub_tree = NULL; proto_item *ti; gint offset = 0; guint8 extension_type; conversation = find_or_create_conversation(pinfo); conversation_set_dissector(conversation, bt_utp_handle); /* set the protocol column */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "BT-uTP"); /* set the info column */ col_set_str( pinfo->cinfo, COL_INFO, "uTorrent Transport Protocol" ); len_tvb = tvb_reported_length(tvb); ti = proto_tree_add_protocol_format(tree, proto_bt_utp, tvb, 0, -1, "uTorrent Transport Protocol V%d (%d bytes)", version, len_tvb); sub_tree = proto_item_add_subtree(ti, ett_bt_utp); /* Determine header version */ if (version == 0) { offset = dissect_utp_header_v0(tvb, pinfo, sub_tree, offset, &extension_type); } else { offset = dissect_utp_header_v1(tvb, pinfo, sub_tree, offset, &extension_type); } offset = dissect_utp_extension(tvb, pinfo, sub_tree, offset, &extension_type); len_tvb = tvb_captured_length_remaining(tvb, offset); if(len_tvb > 0) proto_tree_add_item(sub_tree, hf_bt_utp_data, tvb, offset, len_tvb, ENC_NA); return offset+len_tvb; } return 0; } void proto_register_bt_utp(void) { static hf_register_info hf[] = { { &hf_bt_utp_ver, { "Version", "bt-utp.ver", FT_UINT8, BASE_DEC, NULL, 0x0F, NULL, HFILL } }, { &hf_bt_utp_flags, { "Flags", "bt-utp.flags", FT_UINT8, BASE_DEC, VALS(bt_utp_type_vals), 0x0, NULL, HFILL } }, { &hf_bt_utp_type, { "Type", "bt-utp.type", FT_UINT8, BASE_DEC, VALS(bt_utp_type_vals), 0xF0, NULL, HFILL } }, { &hf_bt_utp_extension, { "Extension", "bt-utp.extension", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_next_extension_type, { "Next Extension Type", "bt-utp.next_extension_type", FT_UINT8, BASE_DEC, VALS(bt_utp_extension_type_vals), 0x0, NULL, HFILL } }, { &hf_bt_utp_extension_len, { "Extension Length", "bt-utp.extension_len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_extension_bitmask, { "Extension Bitmask", "bt-utp.extension_bitmask", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_extension_unknown, { "Extension Unknown", "bt-utp.extension_unknown", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_connection_id_v0, { "Connection ID", "bt-utp.connection_id", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_connection_id_v1, { "Connection ID", "bt-utp.connection_id", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_timestamp_sec, { "Timestamp seconds", "bt-utp.timestamp_sec", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_timestamp_us, { "Timestamp Microseconds", "bt-utp.timestamp_us", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_timestamp_diff_us, { "Timestamp Difference Microseconds", "bt-utp.timestamp_diff_us", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_wnd_size_v0, { "Windows Size", "bt-utp.wnd_size", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_wnd_size_v1, { "Windows Size", "bt-utp.wnd_size", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_seq_nr, { "Sequence number", "bt-utp.seq_nr", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_ack_nr, { "ACK number", "bt-utp.ack_nr", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_data, { "Data", "bt-utp.data", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, }; /* Setup protocol subtree array */ static gint *ett[] = { &ett_bt_utp, &ett_bt_utp_extension }; module_t *bt_utp_module; /* Register protocol */ proto_bt_utp = proto_register_protocol ("uTorrent Transport Protocol", "BT-uTP", "bt-utp"); bt_utp_module = prefs_register_protocol(proto_bt_utp, NULL); prefs_register_obsolete_preference(bt_utp_module, "enable"); proto_register_field_array(proto_bt_utp, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } void proto_reg_handoff_bt_utp(void) { /* disabled by default since heuristic is weak */ heur_dissector_add("udp", dissect_bt_utp, "BitTorrent UTP over UDP", "bt_utp_udp", proto_bt_utp, HEURISTIC_DISABLE); bt_utp_handle = create_dissector_handle(dissect_bt_utp, proto_bt_utp); dissector_add_for_decode_as_with_preference("udp.port", bt_utp_handle); } /* * Editor modelines * * Local Variables: * c-basic-offset: 2 * tab-width: 8 * indent-tabs-mode: nil * End: * * ex: set shiftwidth=2 tabstop=8 expandtab: * :indentSize=2:tabSize=8:noTabs=true: */