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packet-bt-utp.c
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packet-bt-utp.c
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/* packet-bt-utp.c
* Routines for BT-UTP dissection
* Copyright 2011, Xiao Xiangquan <xiaoxiangquan@gmail.com>
*
* $Id$
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/conversation.h>
#include <epan/prefs.h>
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;
static gboolean bt_utp_enable_heuristic_dissection = FALSE; /* disabled by default since heuristic is weak */
/* --- "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;
void proto_reg_handoff_bt_utp(void);
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_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_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", /* name */
"BT-uTP", /* short name */
"bt-utp" /* abbrev */
);
bt_utp_module = prefs_register_protocol(proto_bt_utp, proto_reg_handoff_bt_utp);
prefs_register_bool_preference(bt_utp_module, "enable", "Enable BT-uTP heuristic dissection",
"Enable BT-uTP heuristic dissection (default is disabled)",
&bt_utp_enable_heuristic_dissection);
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)
{
static gboolean prefs_initialized = FALSE;
if (!prefs_initialized) {
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);
prefs_initialized = TRUE;
}
heur_dissector_set_enabled("udp", dissect_bt_utp, proto_bt_utp, bt_utp_enable_heuristic_dissection);
}
/*
* 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:
*/