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/* packet-tdmoe.c
* Routines for TDM over Ethernet packet disassembly
* Copyright 2010, Haakon Nessjoen <haakon.nessjoen@gmail.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/etypes.h>
#include <epan/prefs.h>
/* Bitmasks for the flags in the fourth byte of the packet */
#define TDMOE_YELLOW_ALARM_BITMASK 0x01
#define TDMOE_SIGBITS_BITMASK 0x02
void proto_reg_handoff_tdmoe(void);
void proto_register_tdmoe(void);
static dissector_handle_t tdmoe_handle;
/* protocols and header fields */
static int proto_tdmoe;
static int hf_tdmoe_subaddress;
static int hf_tdmoe_samples;
static int hf_tdmoe_flags;
static int hf_tdmoe_yellow_alarm;
static int hf_tdmoe_sig_bits_present;
static int hf_tdmoe_packet_counter;
static int hf_tdmoe_channels;
static int hf_tdmoe_sig_bits;
static int ett_tdmoe;
static int ett_tdmoe_flags;
static dissector_handle_t lapd_handle;
static int pref_tdmoe_d_channel = 24;
static int
dissect_tdmoe(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti;
proto_tree *tdmoe_tree;
tvbuff_t *next_client;
uint16_t channels;
uint16_t subaddress;
int32_t offset = 0;
static int * const flags[] = { &hf_tdmoe_yellow_alarm, &hf_tdmoe_sig_bits_present, NULL };
int chan;
/* Check that there's enough data */
if (tvb_captured_length(tvb) < 8)
return 0;
subaddress = tvb_get_ntohs(tvb, 0);
channels = tvb_get_ntohs(tvb, 6);
col_set_str(pinfo->cinfo, COL_PROTOCOL, "TDMoE");
col_add_fstr(pinfo->cinfo, COL_INFO, "Subaddress: %d Channels: %d %s",
subaddress,
channels,
(tvb_get_uint8(tvb, 3) & TDMOE_YELLOW_ALARM_BITMASK ? "[YELLOW ALARM]" : "")
);
/* create display subtree for the protocol */
ti = proto_tree_add_item(tree, proto_tdmoe, tvb, 0, -1, ENC_NA);
tdmoe_tree = proto_item_add_subtree(ti, ett_tdmoe);
/* Subaddress */
proto_tree_add_item(tdmoe_tree, hf_tdmoe_subaddress, tvb, offset, 2, ENC_BIG_ENDIAN);
offset+=2;
/* Samples (1 byte) */
proto_tree_add_item(tdmoe_tree, hf_tdmoe_samples, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
/* Yellow alarm & "Sig bits present" bits (1 byte) */
proto_tree_add_bitmask(tdmoe_tree, tvb, offset, hf_tdmoe_flags, ett_tdmoe_flags, flags, ENC_BIG_ENDIAN);
offset++;
/* Packet counter (2 bytes) */
proto_tree_add_item(tdmoe_tree, hf_tdmoe_packet_counter, tvb, offset, 2, ENC_BIG_ENDIAN);
offset+=2;
/* Number of channels in packet (2 bytes) */
proto_tree_add_item(tdmoe_tree, hf_tdmoe_channels, tvb, offset, 2, ENC_BIG_ENDIAN);
offset+=2;
if (tvb_get_uint8(tvb, 3) & TDMOE_SIGBITS_BITMASK) {
/* 4 sigbits per channel. Might be different on other sub-protocols? */
uint16_t length = (channels >> 1) + ((channels & 0x01) ? 1 : 0);
proto_tree_add_item(tdmoe_tree, hf_tdmoe_sig_bits, tvb, offset, length, ENC_NA);
offset += length;
}
/* The rest is SAMPLES * CHANNELS bytes of channel data */
for (chan = 1; chan <= channels; chan++) {
next_client = tvb_new_subset_length(tvb, offset + ((chan - 1) * 8), 8);
if (chan == pref_tdmoe_d_channel) {
call_dissector(lapd_handle, next_client, pinfo, tree);
} else {
call_data_dissector(next_client, pinfo, tree);
}
}
return 1;
}
void
proto_register_tdmoe(void)
{
static hf_register_info hf[] = {
{ &hf_tdmoe_subaddress,
{ "Subaddress", "tdmoe.subaddress", FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_tdmoe_samples,
{ "Samples", "tdmoe.samples", FT_UINT8, BASE_DEC, NULL, 0x0,
"Samples per channel", HFILL }},
{ &hf_tdmoe_flags,
{ "Flags", "tdmoe.flags", FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_tdmoe_yellow_alarm,
{ "Yellow Alarm", "tdmoe.yellowalarm", FT_BOOLEAN, 8, NULL, TDMOE_YELLOW_ALARM_BITMASK,
NULL, HFILL }},
{ &hf_tdmoe_sig_bits_present,
{ "Sig bits present", "tdmoe.sig_bits_present", FT_BOOLEAN, 8, NULL, TDMOE_SIGBITS_BITMASK,
NULL, HFILL }},
{ &hf_tdmoe_packet_counter,
{ "Counter", "tdmoe.counter", FT_UINT16, BASE_DEC, NULL, 0x0,
"Packet number", HFILL }},
{ &hf_tdmoe_channels,
{ "Channels", "tdmoe.channels", FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_tdmoe_sig_bits,
{ "Sig bits", "tdmoe.sig_bits", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
};
static int *ett[] = {
&ett_tdmoe,
&ett_tdmoe_flags
};
module_t *tdmoe_module;
proto_tdmoe = proto_register_protocol("Digium TDMoE Protocol", "TDMoE", "tdmoe");
proto_register_field_array(proto_tdmoe, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
tdmoe_handle = register_dissector("tdmoe", dissect_tdmoe, proto_tdmoe);
tdmoe_module = prefs_register_protocol(proto_tdmoe, NULL);
prefs_register_uint_preference(tdmoe_module, "d_channel",
"TDMoE D-Channel",
"The TDMoE channel that contains the D-Channel.",
10, &pref_tdmoe_d_channel);
}
void
proto_reg_handoff_tdmoe(void)
{
dissector_add_uint("ethertype", ETHERTYPE_TDMOE, tdmoe_handle);
lapd_handle = find_dissector_add_dependency("lapd-bitstream", proto_tdmoe);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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