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/* packet-at-ldf.c
* Dissector for Allied Telesis Loop Detection Frames
*
* Copyright (c) 2021-2024 by Martin Mayer <martin.mayer@m2-it-solutions.de>
*
* 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>
#define AT_LDF_LLC_CTRL 0xE3
#define AT_LDF_FRAME_LEN 79
void proto_register_at_ldf(void);
void proto_reg_handoff_at_ldf(void);
static dissector_handle_t at_ldf_handle;
static int proto_at_ldf;
/* Fields */
static int hf_at_ldf_version;
static int hf_at_ldf_src_vlan;
static int hf_at_ldf_src_port;
static int hf_at_ldf_ttl;
static int hf_at_ldf_id;
static int hf_at_ldf_text;
static gint ett_at_ldf;
static int
dissect_at_ldf(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
/*
* Packet description
*
* The frame is an LLC frame (non-SNAP) with DSAP=0, SSAP=0, Control=0xE3.
* Ethernet destination address is the non-existing device address
* with Allied Telesis OUI (00:00:f4:27:71:01).
*
* The payload contains information about protocol version, source VLAN and port,
* TTL, random LDF identifier and an informational text.
*/
/* Check if packet is destined to the Allied Telesis test address (00:00:F4:27:71:01) */
guint8 dst_mac[6] = {0x00, 0x00, 0xF4, 0x27, 0x71, 0x01};
address dst_addr = ADDRESS_INIT_NONE;
set_address(&dst_addr, AT_ETHER, sizeof(dst_mac), &dst_mac);
if(!addresses_equal(&pinfo->dl_dst, &dst_addr))
return 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "AT LDF");
col_clear(pinfo->cinfo,COL_INFO);
col_add_fstr(pinfo->cinfo, COL_INFO, "Source VLAN: %u, Port: %u",
tvb_get_guint16(tvb, 1, ENC_BIG_ENDIAN),
tvb_get_guint16(tvb, 5, ENC_BIG_ENDIAN));
/* Frame has fixed length, so we can directly set tree and reported length */
tvb_set_reported_length(tvb, AT_LDF_FRAME_LEN);
proto_item *ti = proto_tree_add_item(tree, proto_at_ldf, tvb, 0, AT_LDF_FRAME_LEN, ENC_NA);
proto_tree *at_ldf_tree = proto_item_add_subtree(ti, ett_at_ldf);
gint offset = 0;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_version, tvb, offset, 1, ENC_BIG_ENDIAN);
offset += 1;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_src_vlan, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_src_port, tvb, offset, 4, ENC_BIG_ENDIAN);
offset += 4;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_ttl, tvb, offset, 1, ENC_BIG_ENDIAN);
offset += 1;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_id, tvb, offset, 7, ENC_NA);
offset += 7;
proto_tree_add_item(at_ldf_tree, hf_at_ldf_text, tvb, offset, 64, ENC_ASCII);
return AT_LDF_FRAME_LEN;
}
void
proto_register_at_ldf(void)
{
static hf_register_info hf[] = {
{ &hf_at_ldf_version,
{ "Version", "atldf.version",
FT_UINT8, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_at_ldf_src_vlan,
{ "Source VLAN", "atldf.vlan",
FT_UINT16, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_at_ldf_src_port,
{ "Source Port", "atldf.port",
FT_UINT32, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_at_ldf_ttl,
{ "Time to Live", "atldf.ttl",
FT_UINT8, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_at_ldf_id,
{ "Identifier", "atldf.id",
FT_UINT56, BASE_HEX,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_at_ldf_text,
{ "Information", "atldf.info",
FT_STRINGZPAD, BASE_NONE,
NULL, 0x0,
NULL, HFILL }
}
};
static gint *ett[] = {
&ett_at_ldf
};
proto_at_ldf = proto_register_protocol ("Allied Telesis Loop Detection", "AT LDF", "atldf");
proto_register_field_array(proto_at_ldf, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
at_ldf_handle = register_dissector("atldf", dissect_at_ldf, proto_at_ldf);
}
void
proto_reg_handoff_at_ldf(void)
{
dissector_add_uint("llc.control", AT_LDF_LLC_CTRL, at_ldf_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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