![Anders Broman](/assets/img/avatar_default.png)
makes the TDMoE dissector call the LAPD bitstream dissector on the D-Channel. As a result, LAPD calls Q.931, and you can actually see call setup and tear down, instead of just a hex dump. It adds a preference for which channel the D-Channel is. It patches the LAPD code to fix a few bugs, not pass the checksum to Q.931 (who isn't expecting it), to register the lapd-bitstream dissector, and to mark packets with aborts or resets. also storing more data on the lapd_byte_state_t. https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=8374 svn path=/trunk/; revision=48743
188 lines
5.8 KiB
C
188 lines
5.8 KiB
C
/* packet-tdmoe.c
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* Routines for TDM over Ethernet packet disassembly
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* Copyright 2010, Haakon Nessjoen <haakon.nessjoen@gmail.com>
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*
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* $Id$
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "config.h"
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/etypes.h>
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#include <epan/prefs.h>
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/* Bitmasks for the flags in the fourth byte of the packet */
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#define TDMOE_YELLOW_ALARM_BITMASK 0x01
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#define TDMOE_SIGBITS_BITMASK 0x02
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/* protocols and header fields */
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static int proto_tdmoe = -1;
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static int hf_tdmoe_subaddress = -1;
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static int hf_tdmoe_samples = -1;
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static int hf_tdmoe_flags = -1;
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static int hf_tdmoe_yellow_alarm = -1;
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static int hf_tdmoe_sig_bits_present = -1;
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static int hf_tdmoe_packet_counter = -1;
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static int hf_tdmoe_channels = -1;
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static int hf_tdmoe_sig_bits = -1;
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static gint ett_tdmoe = -1;
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static gint ett_tdmoe_flags = -1;
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static dissector_handle_t lapd_handle;
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static dissector_handle_t data_handle;
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static gint pref_tdmoe_d_channel = 24;
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void proto_reg_handoff_tdmoe(void);
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static int
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dissect_tdmoe(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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proto_item *ti;
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proto_tree *tdmoe_tree;
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tvbuff_t *next_client;
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guint16 channels;
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guint16 subaddress;
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gint32 offset = 0;
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static const gint *flags[] = { &hf_tdmoe_yellow_alarm, &hf_tdmoe_sig_bits_present, NULL };
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int chan;
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/* Check that there's enough data */
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if (tvb_length(tvb) < 8)
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return 0;
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subaddress = tvb_get_ntohs(tvb, 0);
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channels = tvb_get_ntohs(tvb, 6);
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "TDMoE");
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col_add_fstr(pinfo->cinfo, COL_INFO, "Subaddress: %d Channels: %d %s",
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subaddress,
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channels,
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(tvb_get_guint8(tvb, 3) & TDMOE_YELLOW_ALARM_BITMASK ? "[YELLOW ALARM]" : "")
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);
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/* create display subtree for the protocol */
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ti = proto_tree_add_item(tree, proto_tdmoe, tvb, 0, -1, ENC_NA);
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tdmoe_tree = proto_item_add_subtree(ti, ett_tdmoe);
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/* Subaddress */
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proto_tree_add_item(tdmoe_tree, hf_tdmoe_subaddress, tvb, offset, 2, ENC_BIG_ENDIAN);
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offset+=2;
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/* Samples (1 byte) */
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proto_tree_add_item(tdmoe_tree, hf_tdmoe_samples, tvb, offset, 1, ENC_NA);
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offset++;
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/* Yellow alarm & "Sig bits present" bits (1 byte) */
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proto_tree_add_bitmask(tdmoe_tree, tvb, offset, hf_tdmoe_flags, ett_tdmoe_flags, flags, ENC_BIG_ENDIAN);
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offset++;
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/* Packet counter (2 bytes) */
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proto_tree_add_item(tdmoe_tree, hf_tdmoe_packet_counter, tvb, offset, 2, ENC_BIG_ENDIAN);
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offset+=2;
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/* Number of channels in packet (2 bytes) */
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proto_tree_add_item(tdmoe_tree, hf_tdmoe_channels, tvb, offset, 2, ENC_BIG_ENDIAN);
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offset+=2;
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if (tvb_get_guint8(tvb, 3) & TDMOE_SIGBITS_BITMASK) {
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/* 4 sigbits per channel. Might be different on other sub-protocols? */
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guint16 length = (channels >> 1) + ((channels & 0x01) ? 1 : 0);
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proto_tree_add_item(tdmoe_tree, hf_tdmoe_sig_bits, tvb, offset, length, ENC_NA);
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offset += length;
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}
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/* The rest is SAMPLES * CHANNELS bytes of channel data */
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for (chan = 1; chan <= channels; chan++) {
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next_client = tvb_new_subset_length(tvb, offset + ((chan - 1) * 8), 8);
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if (chan == pref_tdmoe_d_channel) {
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call_dissector(lapd_handle, next_client, pinfo, tree);
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} else {
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call_dissector(data_handle, next_client, pinfo, tree);
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}
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}
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return 1;
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}
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void
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proto_register_tdmoe(void)
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{
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static hf_register_info hf[] = {
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{ &hf_tdmoe_subaddress,
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{ "Subaddress", "tdmoe.subaddress", FT_UINT8, BASE_DEC, NULL, 0x0,
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NULL, HFILL }},
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{ &hf_tdmoe_samples,
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{ "Samples", "tdmoe.samples", FT_UINT8, BASE_DEC, NULL, 0x0,
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"Samples per channel", HFILL }},
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{ &hf_tdmoe_flags,
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{ "Flags", "tdmoe.flags", FT_UINT8, BASE_HEX, NULL, 0x0,
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NULL, HFILL }},
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{ &hf_tdmoe_yellow_alarm,
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{ "Yellow Alarm", "tdmoe.yellowalarm", FT_BOOLEAN, 8, NULL, TDMOE_YELLOW_ALARM_BITMASK,
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NULL, HFILL }},
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{ &hf_tdmoe_sig_bits_present,
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{ "Sig bits present", "tdmoe.sig_bits_present", FT_BOOLEAN, 8, NULL, TDMOE_SIGBITS_BITMASK,
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NULL, HFILL }},
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{ &hf_tdmoe_packet_counter,
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{ "Counter", "tdmoe.counter", FT_UINT16, BASE_DEC, NULL, 0x0,
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"Packet number", HFILL }},
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{ &hf_tdmoe_channels,
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{ "Channels", "tdmoe.channels", FT_UINT16, BASE_DEC, NULL, 0x0,
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NULL, HFILL }},
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{ &hf_tdmoe_sig_bits,
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{ "Sig bits", "tdmoe.sig_bits", FT_BYTES, BASE_NONE, NULL, 0x0,
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NULL, HFILL }},
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};
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static gint *ett[] = {
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&ett_tdmoe,
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&ett_tdmoe_flags
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};
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module_t *tdmoe_module;
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proto_tdmoe = proto_register_protocol("Digium TDMoE Protocol", "TDMoE", "tdmoe");
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proto_register_field_array(proto_tdmoe, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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tdmoe_module = prefs_register_protocol(proto_tdmoe, proto_reg_handoff_tdmoe);
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prefs_register_uint_preference(tdmoe_module, "d_channel",
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"TDMoE D-Channel",
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"The TDMoE channel that contains the D-Channel.",
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10, &pref_tdmoe_d_channel);
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}
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void
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proto_reg_handoff_tdmoe(void)
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{
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dissector_handle_t tdmoe_handle;
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tdmoe_handle = new_create_dissector_handle(dissect_tdmoe, proto_tdmoe);
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dissector_add_uint("ethertype", ETHERTYPE_TDMOE, tdmoe_handle);
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lapd_handle = find_dissector("lapd-bitstream");
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data_handle = find_dissector("data");
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}
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