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wireshark/epan/dissectors/packet-mtp2.c

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/* packet-mtp2.c
* Routines for MTP2 dissection
* It is hopefully (needs testing) compliant to
* ITU-T Q.703 and Q.703 Annex A.
*
* Copyright 2001, 2004 Michael Tuexen <tuexen [AT] fh-muenster.de>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* Copied from packet-m2pa.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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/prefs.h>
#include <epan/crc16-tvb.h>
#include <epan/expert.h>
#include <wiretap/wtap.h>
void proto_register_mtp2(void);
void proto_reg_handoff_mtp2(void);
static dissector_handle_t mtp2_handle;
/* Initialize the protocol and registered fields */
static int proto_mtp2 = -1;
static int hf_mtp2_bsn = -1;
static int hf_mtp2_ext_bsn = -1;
static int hf_mtp2_ext_res = -1;
static int hf_mtp2_bib = -1;
static int hf_mtp2_ext_bib = -1;
static int hf_mtp2_fsn = -1;
static int hf_mtp2_ext_fsn = -1;
static int hf_mtp2_fib = -1;
static int hf_mtp2_ext_fib = -1;
static int hf_mtp2_li = -1;
static int hf_mtp2_ext_li = -1;
static int hf_mtp2_spare = -1;
static int hf_mtp2_ext_spare = -1;
static int hf_mtp2_sf = -1;
static int hf_mtp2_sf_extra = -1;
static int hf_mtp2_fcs_16 = -1;
static expert_field ei_mtp2_checksum_error = EI_INIT;
/* Initialize the subtree pointers */
static gint ett_mtp2 = -1;
static dissector_handle_t mtp3_handle;
static gboolean use_extended_sequence_numbers_default = FALSE;
#define BSN_BIB_LENGTH 1
#define FSN_FIB_LENGTH 1
#define LI_LENGTH 1
#define HEADER_LENGTH (BSN_BIB_LENGTH + FSN_FIB_LENGTH + LI_LENGTH)
#define EXTENDED_BSN_BIB_LENGTH 2
#define EXTENDED_FSN_FIB_LENGTH 2
#define EXTENDED_LI_LENGTH 2
#define EXTENDED_HEADER_LENGTH (EXTENDED_BSN_BIB_LENGTH + EXTENDED_FSN_FIB_LENGTH + EXTENDED_LI_LENGTH)
#define BSN_BIB_OFFSET 0
#define FSN_FIB_OFFSET (BSN_BIB_OFFSET + BSN_BIB_LENGTH)
#define LI_OFFSET (FSN_FIB_OFFSET + FSN_FIB_LENGTH)
#define SIO_OFFSET (LI_OFFSET + LI_LENGTH)
#define EXTENDED_BSN_BIB_OFFSET 0
#define EXTENDED_FSN_FIB_OFFSET (EXTENDED_BSN_BIB_OFFSET + EXTENDED_BSN_BIB_LENGTH)
#define EXTENDED_LI_OFFSET (EXTENDED_FSN_FIB_OFFSET + EXTENDED_FSN_FIB_LENGTH)
#define EXTENDED_SIO_OFFSET (EXTENDED_LI_OFFSET + EXTENDED_LI_LENGTH)
#define BSN_MASK 0x7f
#define BIB_MASK 0x80
#define FSN_MASK 0x7f
#define FIB_MASK 0x80
#define LI_MASK 0x3f
#define SPARE_MASK 0xc0
#define EXTENDED_BSN_MASK 0x0fff
#define EXTENDED_RES_MASK 0x7000
#define EXTENDED_BIB_MASK 0x8000
#define EXTENDED_FSN_MASK 0x0fff
#define EXTENDED_FIB_MASK 0x8000
#define EXTENDED_LI_MASK 0x01ff
#define EXTENDED_SPARE_MASK 0xfe00
static void
dissect_mtp2_header(tvbuff_t *su_tvb, proto_item *mtp2_tree, gboolean use_extended_sequence_numbers)
{
if (mtp2_tree) {
if (use_extended_sequence_numbers) {
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_bsn, su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_res, su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_bib, su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_fsn, su_tvb, EXTENDED_FSN_FIB_OFFSET, EXTENDED_FSN_FIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_res, su_tvb, EXTENDED_BSN_BIB_OFFSET, EXTENDED_BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_fib, su_tvb, EXTENDED_FSN_FIB_OFFSET, EXTENDED_FSN_FIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_li, su_tvb, EXTENDED_LI_OFFSET, EXTENDED_LI_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_ext_spare, su_tvb, EXTENDED_LI_OFFSET, EXTENDED_LI_LENGTH, ENC_LITTLE_ENDIAN);
} else {
proto_tree_add_item(mtp2_tree, hf_mtp2_bsn, su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_bib, su_tvb, BSN_BIB_OFFSET, BSN_BIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_fsn, su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_fib, su_tvb, FSN_FIB_OFFSET, FSN_FIB_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_li, su_tvb, LI_OFFSET, LI_LENGTH, ENC_LITTLE_ENDIAN);
proto_tree_add_item(mtp2_tree, hf_mtp2_spare, su_tvb, LI_OFFSET, LI_LENGTH, ENC_LITTLE_ENDIAN);
}
}
}
/*
*******************************************************************************
* DETAILS : Calculate a new FCS-16 given the current FCS-16 and the new data.
*******************************************************************************
*/
static guint16
mtp2_fcs16(tvbuff_t * tvbuff)
{
guint len = tvb_reported_length(tvbuff)-2;
/* Check for Invalid Length */
if (len == 0)
return (0x0000);
return crc16_ccitt_tvb(tvbuff, len);
}
/*
* This function for CRC16 only is based on the decode_fcs of packet_ppp.c
*/
static tvbuff_t *
mtp2_decode_crc16(tvbuff_t *tvb, proto_tree *fh_tree, packet_info *pinfo)
{
tvbuff_t *next_tvb;
gint len, reported_len;
int proto_offset=0;
/*
* Do we have the entire packet, and does it include a 2-byte FCS?
*/
len = tvb_reported_length_remaining(tvb, proto_offset);
reported_len = tvb_reported_length_remaining(tvb, proto_offset);
if (reported_len < 2 || len < 0) {
/*
* The packet is claimed not to even have enough data for a 2-byte FCS,
* or we're already past the end of the captured data.
* Don't slice anything off.
*/
next_tvb = tvb_new_subset_remaining(tvb, proto_offset);
} else if (len < reported_len) {
/*
* The packet is claimed to have enough data for a 2-byte FCS, but
* we didn't capture all of the packet.
* Slice off the 2-byte FCS from the reported length, and trim the
* captured length so it's no more than the reported length; that
* will slice off what of the FCS, if any, is in the captured
* length.
*/
reported_len -= 2;
if (len > reported_len)
len = reported_len;
next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
} else {
/*
* We have the entire packet, and it includes a 2-byte FCS.
* Slice it off.
*/
len -= 2;
reported_len -= 2;
next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
/*
* Compute the FCS and put it into the tree.
*/
proto_tree_add_checksum(fh_tree, tvb, proto_offset + len, hf_mtp2_fcs_16, -1, &ei_mtp2_checksum_error, pinfo, mtp2_fcs16(tvb),
ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
}
return next_tvb;
}
static void
dissect_mtp2_fisu(packet_info *pinfo)
{
col_set_str(pinfo->cinfo, COL_INFO, "FISU ");
}
static const value_string status_field_vals[] = {
{ 0x0, "Status Indication O" },
{ 0x1, "Status Indication N" },
{ 0x2, "Status Indication E" },
{ 0x3, "Status Indication OS" },
{ 0x4, "Status Indication PO" },
{ 0x5, "Status Indication B" },
{ 0, NULL}
};
/* Same as above but in acronym form (for the Info column) */
static const value_string status_field_acro_vals[] = {
{ 0x0, "SIO" },
{ 0x1, "SIN" },
{ 0x2, "SIE" },
{ 0x3, "SIOS" },
{ 0x4, "SIPO" },
{ 0x5, "SIB" },
{ 0, NULL}
};
#define SF_OFFSET (LI_OFFSET + LI_LENGTH)
#define EXTENDED_SF_OFFSET (EXTENDED_LI_OFFSET + EXTENDED_LI_LENGTH)
#define SF_LENGTH 1
#define SF_EXTRA_OFFSET (SF_OFFSET + SF_LENGTH)
#define EXTENDED_SF_EXTRA_OFFSET (EXTENDED_SF_OFFSET + SF_LENGTH)
#define SF_EXTRA_LENGTH 1
static void
dissect_mtp2_lssu(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_tree,
gboolean use_extended_sequence_numbers)
{
guint8 sf = 0xFF;
guint8 sf_offset, sf_extra_offset;
if (use_extended_sequence_numbers) {
sf_offset = EXTENDED_SF_OFFSET;
sf_extra_offset = EXTENDED_SF_EXTRA_OFFSET;
} else {
sf_offset = SF_OFFSET;
sf_extra_offset = SF_EXTRA_OFFSET;
}
proto_tree_add_item(mtp2_tree, hf_mtp2_sf, su_tvb, sf_offset, SF_LENGTH, ENC_LITTLE_ENDIAN);
sf = tvb_get_guint8(su_tvb, SF_OFFSET);
/* If the LI is 2 then there is an extra octet following the standard SF
* field but it is not defined what this octet is.
* (In any case the first byte of the SF always has the same meaning.)
*/
if ((tvb_get_guint8(su_tvb, LI_OFFSET) & LI_MASK) == 2)
proto_tree_add_item(mtp2_tree, hf_mtp2_sf_extra, su_tvb, sf_extra_offset, SF_EXTRA_LENGTH, ENC_LITTLE_ENDIAN);
col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(sf, status_field_acro_vals, "Unknown"));
}
static void
dissect_mtp2_msu(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_item,
proto_item *tree, gboolean use_extended_sequence_numbers)
{
gint sif_sio_length;
tvbuff_t *sif_sio_tvb;
col_set_str(pinfo->cinfo, COL_INFO, "MSU ");
if (use_extended_sequence_numbers) {
sif_sio_length = tvb_reported_length(su_tvb) - EXTENDED_HEADER_LENGTH;
sif_sio_tvb = tvb_new_subset_length(su_tvb, EXTENDED_SIO_OFFSET, sif_sio_length);
} else {
sif_sio_length = tvb_reported_length(su_tvb) - HEADER_LENGTH;
sif_sio_tvb = tvb_new_subset_length(su_tvb, SIO_OFFSET, sif_sio_length);
}
call_dissector(mtp3_handle, sif_sio_tvb, pinfo, tree);
if (tree) {
if (use_extended_sequence_numbers)
proto_item_set_len(mtp2_item, EXTENDED_HEADER_LENGTH);
else
proto_item_set_len(mtp2_item, HEADER_LENGTH);
}
}
static void
dissect_mtp2_su(tvbuff_t *su_tvb, packet_info *pinfo, proto_item *mtp2_item,
proto_item *mtp2_tree, proto_tree *tree, gboolean validate_crc,
gboolean use_extended_sequence_numbers)
{
guint16 li;
tvbuff_t *next_tvb = NULL;
dissect_mtp2_header(su_tvb, mtp2_tree, use_extended_sequence_numbers);
if (validate_crc)
next_tvb = mtp2_decode_crc16(su_tvb, mtp2_tree, pinfo);
if (use_extended_sequence_numbers)
li = tvb_get_letohs(su_tvb, EXTENDED_LI_OFFSET) & EXTENDED_LI_MASK;
else
li = tvb_get_guint8(su_tvb, LI_OFFSET) & LI_MASK;
switch(li) {
case 0:
dissect_mtp2_fisu(pinfo);
break;
case 1:
case 2:
if (validate_crc)
dissect_mtp2_lssu(next_tvb, pinfo, mtp2_tree, use_extended_sequence_numbers);
else
dissect_mtp2_lssu(su_tvb, pinfo, mtp2_tree, use_extended_sequence_numbers);
break;
default:
/* In some capture files (like .rf5), CRC are not present */
/* So, to avoid trouble, give the complete buffer if CRC validation is disabled */
if (validate_crc)
dissect_mtp2_msu(next_tvb, pinfo, mtp2_item, tree, use_extended_sequence_numbers);
else
dissect_mtp2_msu(su_tvb, pinfo, mtp2_item, tree, use_extended_sequence_numbers);
break;
}
}
static void
dissect_mtp2_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
gboolean validate_crc, gboolean use_extended_sequence_numbers)
{
proto_item *mtp2_item;
proto_tree *mtp2_tree;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MTP2");
mtp2_item = proto_tree_add_item(tree, proto_mtp2, tvb, 0, -1, ENC_NA);
mtp2_tree = proto_item_add_subtree(mtp2_item, ett_mtp2);
dissect_mtp2_su(tvb, pinfo, mtp2_item, mtp2_tree, tree, validate_crc,
use_extended_sequence_numbers);
}
/* Dissect MTP2 frame without CRC16 and with a pseudo-header */
static int
dissect_mtp2_with_phdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
if (pinfo->pseudo_header->mtp2.annex_a_used == MTP2_ANNEX_A_USED_UNKNOWN)
dissect_mtp2_common(tvb, pinfo, tree, FALSE, use_extended_sequence_numbers_default);
else
dissect_mtp2_common(tvb, pinfo, tree, FALSE,
(pinfo->pseudo_header->mtp2.annex_a_used == MTP2_ANNEX_A_USED));
return tvb_captured_length(tvb);
}
/* Dissect MTP2 frame with CRC16 included at end of payload */
static int
dissect_mtp2_with_crc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
dissect_mtp2_common(tvb, pinfo, tree, TRUE, use_extended_sequence_numbers_default);
return tvb_captured_length(tvb);
}
/* Dissect MTP2 frame without CRC16 included at end of payload */
static int
dissect_mtp2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
dissect_mtp2_common(tvb, pinfo, tree, FALSE, use_extended_sequence_numbers_default);
return tvb_captured_length(tvb);
}
void
proto_register_mtp2(void)
{
static hf_register_info hf[] = {
{ &hf_mtp2_bsn, { "Backward sequence number", "mtp2.bsn", FT_UINT8, BASE_DEC, NULL, BSN_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_bsn, { "Backward sequence number", "mtp2.bsn", FT_UINT16, BASE_DEC, NULL, EXTENDED_BSN_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_res, { "Reserved", "mtp2.res", FT_UINT16, BASE_DEC, NULL, EXTENDED_RES_MASK, NULL, HFILL } },
{ &hf_mtp2_bib, { "Backward indicator bit", "mtp2.bib", FT_UINT8, BASE_DEC, NULL, BIB_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_bib, { "Backward indicator bit", "mtp2.bib", FT_UINT16, BASE_DEC, NULL, EXTENDED_BIB_MASK, NULL, HFILL } },
{ &hf_mtp2_fsn, { "Forward sequence number", "mtp2.fsn", FT_UINT8, BASE_DEC, NULL, FSN_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_fsn, { "Forward sequence number", "mtp2.fsn", FT_UINT16, BASE_DEC, NULL, EXTENDED_FSN_MASK, NULL, HFILL } },
{ &hf_mtp2_fib, { "Forward indicator bit", "mtp2.fib", FT_UINT8, BASE_DEC, NULL, FIB_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_fib, { "Forward indicator bit", "mtp2.fib", FT_UINT16, BASE_DEC, NULL, EXTENDED_FIB_MASK, NULL, HFILL } },
{ &hf_mtp2_li, { "Length Indicator", "mtp2.li", FT_UINT8, BASE_DEC, NULL, LI_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_li, { "Length Indicator", "mtp2.li", FT_UINT16, BASE_DEC, NULL, EXTENDED_LI_MASK, NULL, HFILL } },
{ &hf_mtp2_spare, { "Spare", "mtp2.spare", FT_UINT8, BASE_DEC, NULL, SPARE_MASK, NULL, HFILL } },
{ &hf_mtp2_ext_spare, { "Spare", "mtp2.spare", FT_UINT16, BASE_DEC, NULL, EXTENDED_SPARE_MASK, NULL, HFILL } },
{ &hf_mtp2_sf, { "Status field", "mtp2.sf", FT_UINT8, BASE_DEC, VALS(status_field_vals), 0x0, NULL, HFILL } },
{ &hf_mtp2_sf_extra, { "Status field extra octet", "mtp2.sf_extra", FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL } },
{ &hf_mtp2_fcs_16, { "FCS 16", "mtp2.fcs_16", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } },
};
static gint *ett[] = {
&ett_mtp2
};
static ei_register_info ei[] = {
{ &ei_mtp2_checksum_error, { "mtp2.checksum.error", PI_CHECKSUM, PI_WARN, "MTP2 Frame CheckFCS 16 Error", EXPFILL }},
};
module_t *mtp2_module;
expert_module_t* expert_mtp2;
proto_mtp2 = proto_register_protocol("Message Transfer Part Level 2", "MTP2", "mtp2");
mtp2_handle = register_dissector("mtp2", dissect_mtp2, proto_mtp2);
register_dissector("mtp2_with_crc", dissect_mtp2_with_crc, proto_mtp2);
proto_register_field_array(proto_mtp2, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_mtp2 = expert_register_protocol(proto_mtp2);
expert_register_field_array(expert_mtp2, ei, array_length(ei));
mtp2_module = prefs_register_protocol(proto_mtp2, NULL);
prefs_register_bool_preference(mtp2_module,
"use_extended_sequence_numbers",
"Use extended sequence numbers",
"Whether the MTP2 dissector should use extended sequence numbers as described in Q.703, Annex A as a default.",
&use_extended_sequence_numbers_default);
}
void
proto_reg_handoff_mtp2(void)
{
dissector_handle_t mtp2_with_phdr_handle;
dissector_add_uint("wtap_encap", WTAP_ENCAP_MTP2, mtp2_handle);
mtp2_with_phdr_handle = create_dissector_handle(dissect_mtp2_with_phdr,
proto_mtp2);
dissector_add_uint("wtap_encap", WTAP_ENCAP_MTP2_WITH_PHDR,
mtp2_with_phdr_handle);
mtp3_handle = find_dissector_add_dependency("mtp3", proto_mtp2);
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* 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:
*/
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