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/* packet-rtag.c
* Dissector for IEEE 802.1cb R-TAG tags
* By Stephen Williams <steve.williams@getcruise.com>
* Copyright 2020-present, Cruise LLC
*
* 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>
static int proto_rtag = -1;
static dissector_handle_t ethertype_handle;
static dissector_handle_t rtag_handle;
/*
* These values and tables are a breakdown of the R-TAG parts.
*/
static int hf_rtag_reserved = -1;
static int hf_rtag_sequence = -1;
static int hf_rtag_protocol = -1;
static hf_register_info rtag_breakdown[] = {
{ &hf_rtag_reserved,
{ "<reserved>", "rtag.reserved",
FT_UINT16, BASE_HEX,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_rtag_sequence,
{ "Sequence number", "rtag.seqno",
FT_UINT16, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_rtag_protocol,
{ "Type", "rtag.protocol",
FT_UINT16, BASE_HEX,
VALS(etype_vals), 0x0,
"Ethertype", HFILL }
}
};
/*
*/
static gint ett_rtag = -1;
static gint *ett[] = { &ett_rtag };
/*
* Dissect the R-TAG portion of a given packet. This is called with
* the tvb pointing to where our payload starts (i.e. not including
* the 0xf1c1 tag that got us here.)
*/
static int dissect_rtag(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item*ti;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "R-TAG");
/* Clear the info column */
col_clear(pinfo->cinfo, COL_INFO);
/*
* The R-TAG is 6 octets: 2 reserved, 2 sequence number, and
* 2 encapsulated protocol.
*/
ti = proto_tree_add_item(tree, proto_rtag, tvb, 0, 6, ENC_NA);
guint16 seqno = tvb_get_ntohs(tvb, 2);
guint16 rtag_protocol = tvb_get_ntohs(tvb, 4);
proto_tree *rtag_subtree = proto_item_add_subtree(ti, ett_rtag);
proto_tree_add_item(rtag_subtree, hf_rtag_reserved, tvb, 0, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(rtag_subtree, hf_rtag_sequence, tvb, 2, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(rtag_subtree, hf_rtag_protocol, tvb, 4, 2, ENC_BIG_ENDIAN);
/* Add a quick summary in the info column. */
col_add_fstr(pinfo->cinfo, COL_INFO, "R-TAG: %u", seqno);
/*
* Process the encapsulated packet as an encapsulated Ethernet
* PDU. We have the encapsulated protocol type (and ethertype)
* as part of the R-TAG protocol
*/
ethertype_data_t ethertype_data;
ethertype_data.etype = rtag_protocol;;
ethertype_data.payload_offset = 6;
ethertype_data.fh_tree = tree;
ethertype_data.trailer_id = -1;
ethertype_data.fcs_len = -1;
call_dissector_with_data(ethertype_handle, tvb, pinfo, tree, ðertype_data);
return tvb_captured_length(tvb);
}
/*
* This function is called to register a protocol description.
*/
void proto_register_rtag(void)
{
proto_rtag = proto_register_protocol (
"802.1cb R-TAG", /* name */
"R-TAG", /* short name */
"rtag" /* filter_name */
);
proto_register_field_array(proto_rtag, rtag_breakdown,
array_length(rtag_breakdown));
proto_register_subtree_array(ett, array_length(ett));
}
/*
* This function is called to register the actual dissector.
*/
void proto_reg_handoff_rtag(void)
{
rtag_handle = create_dissector_handle(dissect_rtag, proto_rtag);
dissector_add_uint("ethertype", ETHERTYPE_IEEE_802_1CB, rtag_handle);
/* Get a handle for the ethertype dissector. */
ethertype_handle = find_dissector_add_dependency("ethertype", proto_rtag);
}
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