/* packet-bt-utp.c * Routines for BT-UTP dissection * Copyright 2011, Xiao Xiangquan * * $Id$ * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1999 Gerald Combs * * 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 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 -- +-------+-------+---------------+---------------+---------------+ | 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 +-------+-------+---------------+---------------+---------------+ | ver | type | extension | connection_id | +-------+-------+---------------+---------------+---------------+ | timestamp_microseconds | +---------------+---------------+---------------+---------------+ | timestamp_difference_microseconds | +---------------+---------------+---------------+---------------+ | wnd_size | +---------------+---------------+---------------+---------------+ | seq_nr | ack_nr | +---------------+---------------+---------------+---------------+ XXX: It appears that the above is to be interpreted as indicating that 'ver' is in the low-order 4 bits of byte 0 (mask: 0x0f). (See utp.cpp @ https://github.com/bittorrent/libutp) -- Extension Field(s) -- 0 8 16 +---------------+---------------+---------------+---------------+ | extension | len | bitmask +---------------+---------------+---------------+---------------+ | +---------------+---------------+.... */ #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 gint ett_bt_utp = -1; static gint ett_bt_utp_extension = -1; void proto_reg_handoff_bt_utp(void); static gboolean utp_is_v1(tvbuff_t *tvb) { guint8 v1_ver_type; guint8 v1_ext; guint len; 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 FALSE; /* Not V1 (or corrupt) */ } /* The simple heuristic above (based upon code from utp.cpp) suggests the header is "V1"; * However, based upon a capture seen, the simple heuristic does not appear to be sufficient. * So: Also do some length checking: * The length of "V1" frames should be 20, 26, 30, 34, 36, 38, ... * fixed hdr len: 20 * extension(s) len: 6, 10, 14, 16, 18, 20, ... * XXX: this is a hack and should be replaced !! * In fact this heuristic probably fails for some SF_DATA packets since they * presumably can contain a variable number of data bytes after the header. */ len = tvb_reported_length(tvb); if (len < V1_FIXED_HDR_SIZE) { return TRUE; /* Invalid ?: pretend V1 anyways */ } len -= V1_FIXED_HDR_SIZE; if ((len == 0) || (len == 6) || (len == 10) || (len == 14) || ((len > 14) && (len%2 == 0))) { return TRUE; /* looks like V1 */ } return FALSE; /* Not V1 (or corrupt) */ } 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 */ /* Strange: Contrary to BEP-29, in LibuTP (utp.cpp) the first byte has the following definition: packet_type (4 high bits) protocol version (4 low bits) */ 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 */ /* XXX: This code loops thru the packet bytes until reaching the end of the PDU * ignoring the "end-of-list" [EXT_NO_EXTENSION] extension type. * Should we just quit when EXT_NO_EXTENSION is encountered ? */ while(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) { conversation_t *conversation; /* try dissecting */ if( tvb_get_guint8(tvb,0)=='d' ) { proto_tree *sub_tree = NULL; int decoded_length = 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" ); if(tree) { proto_item *ti; ti = proto_tree_add_item(tree, proto_bt_utp, tvb, 0, -1, ENC_NA); sub_tree = proto_item_add_subtree(ti, ett_bt_utp); } /* Determine header version */ if (!utp_is_v1(tvb)) { decoded_length = dissect_utp_header_v0(tvb, pinfo, sub_tree, decoded_length, &extension_type); } else { decoded_length = dissect_utp_header_v1(tvb, pinfo, sub_tree, decoded_length, &extension_type); } decoded_length = dissect_utp_extension(tvb, pinfo, sub_tree, decoded_length, &extension_type); return decoded_length; } 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 NR", "bt-utp.seq_nr", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_bt_utp_ack_nr, { "ACK NR", "bt-utp.ack_nr", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, }; /* Setup protocol subtree array */ static gint *ett[] = { &ett_bt_utp, &ett_bt_utp_extension }; /* Register protocol */ proto_bt_utp = proto_register_protocol ( "uTorrent Transport Protocol", /* name */ "BT-uTP", /* short name */ "bt-utp" /* abbrev */ ); 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) { heur_dissector_add("udp", dissect_bt_utp, proto_bt_utp); bt_utp_handle = new_create_dissector_handle(dissect_bt_utp, proto_bt_utp); dissector_add_handle("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: */