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/* packet-ieee8021CB.c
* Routines for 802.1CB R-tag ethernet header disassembly
*
* Copyright 2020, Rene Nielsen <rene.nielsen@microchip.com>
* In association with Microchip Technology Inc.
*
* 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/capture_dissectors.h>
#include <wsutil/pint.h>
#include <epan/addr_resolv.h>
#include "packet-ipx.h"
#include "packet-llc.h"
#include <epan/etypes.h>
#include <epan/prefs.h>
void proto_register_ieee8021cb(void);
void proto_reg_handoff_ieee8021cb(void);
static dissector_handle_t ethertype_handle;
static capture_dissector_handle_t ipx_cap_handle;
static capture_dissector_handle_t llc_cap_handle;
/* GLOBALS ************************************************************/
static int proto_ieee8021cb = -1;
/* dot1cb R-tag fields */
static int hf_ieee8021cb_res = -1;
static int hf_ieee8021cb_seq = -1;
/* Encapsulated protocol */
static int hf_ieee8021cb_etype = -1;
static gint ett_ieee8021cb = -1;
#define IEEE8021CB_LEN 6
static gboolean
capture_ieee8021cb(const guchar *pd, int offset, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)
{
guint16 encap_proto;
if (!BYTES_ARE_IN_FRAME(offset, len, IEEE8021CB_LEN + 1))
return FALSE;
encap_proto = pntoh16( &pd[offset + IEEE8021CB_LEN - 2] );
if (encap_proto <= IEEE_802_3_MAX_LEN) {
if ( pd[offset + IEEE8021CB_LEN] == 0xff
&& pd[offset + IEEE8021CB_LEN + 1] == 0xff ) {
return call_capture_dissector(ipx_cap_handle, pd, offset + IEEE8021CB_LEN, len, cpinfo, pseudo_header);
}
else {
return call_capture_dissector(llc_cap_handle, pd, offset + IEEE8021CB_LEN, len, cpinfo, pseudo_header);
}
}
return try_capture_dissector("ethertype", encap_proto, pd, offset + IEEE8021CB_LEN, len, cpinfo, pseudo_header);
}
/* Dissector *************************************************************/
static
int dissect_ieee8021cb(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree, void* data _U_)
{
proto_tree *ptree = NULL;
guint16 seq, pro;
ethertype_data_t ethertype_data;
proto_tree *ieee8021cb_tree;
/* add info to column display */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "802.1CB R-Tag");
col_clear(pinfo->cinfo, COL_INFO);
seq = tvb_get_ntohs(tvb, 2);
pro = tvb_get_ntohs(tvb, 4);
col_add_fstr(pinfo->cinfo, COL_INFO, "SEQ: %u", seq);
/* create the protocol tree */
ptree = proto_tree_add_item(tree, proto_ieee8021cb, tvb, 0, IEEE8021CB_LEN, ENC_NA);
ieee8021cb_tree = proto_item_add_subtree(ptree, ett_ieee8021cb);
/* add fields */
proto_tree_add_uint(ieee8021cb_tree, hf_ieee8021cb_seq, tvb, 2, 2, seq);
proto_tree_add_uint(ieee8021cb_tree, hf_ieee8021cb_etype, tvb, 4, 2, pro);
proto_item_append_text(ptree, ", SEQ: %u", seq);
ethertype_data.fh_tree = ieee8021cb_tree;
ethertype_data.fcs_len = 0;
ethertype_data.etype = pro;
ethertype_data.payload_offset = IEEE8021CB_LEN;
/* 802.1CB tags are always followed by an ethertype; call next dissector
based on ethertype */
call_dissector_with_data(ethertype_handle, tvb, pinfo, tree, ðertype_data);
return tvb_captured_length(tvb);
}
void
proto_register_ieee8021cb(void)
{
static hf_register_info hf_1cb[] = {
{ &hf_ieee8021cb_res, {
"Reserved", "ieee8021cb.reserved", FT_UINT16, BASE_HEX,
NULL, 0x0, NULL, HFILL }},
{ &hf_ieee8021cb_seq, {
"SEQ", "ieee8021cb.seq", FT_UINT16, BASE_HEX_DEC,
NULL, 0x0, NULL, HFILL }},
{ &hf_ieee8021cb_etype, {
"Type", "ieee8021cb.etype", FT_UINT16, BASE_HEX,
VALS(etype_vals), 0x0, "Ethertype", HFILL }}
};
static gint *ett[] = {
&ett_ieee8021cb
};
/* registration */
proto_ieee8021cb = proto_register_protocol("802.1CB Redundancy Tag", "R-Tag", "ieee8021cb");
proto_register_field_array(proto_ieee8021cb, hf_1cb, array_length(hf_1cb));
proto_register_subtree_array(ett, array_length(ett));
}
void
proto_reg_handoff_ieee8021cb(void)
{
static dissector_handle_t ieee8021cb_handle;
static capture_dissector_handle_t ieee8021cb_cap_handle;
ieee8021cb_handle = create_dissector_handle(dissect_ieee8021cb, proto_ieee8021cb);
dissector_add_uint("ethertype", ETHERTYPE_IEEE_802_1CB, ieee8021cb_handle);
ethertype_handle = find_dissector_add_dependency("ethertype", proto_ieee8021cb);
ieee8021cb_cap_handle = create_capture_dissector_handle(capture_ieee8021cb, proto_ieee8021cb);
capture_dissector_add_uint("ethertype", ETHERTYPE_IEEE_802_1CB, ieee8021cb_cap_handle);
ipx_cap_handle = find_capture_dissector("ipx");
llc_cap_handle = find_capture_dissector("llc");
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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