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/* packet-xns-llc.c
* Routines for 3Com's encapsulation of XNS over 802.2 LLC
* (and other protocols using DSAP 80)
*
* 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>
/* Forward declarations */
void proto_register_3com_xns(void);
void proto_reg_handoff_3com_xns(void);
static dissector_handle_t our_xns_handle;
static int proto_3com_xns;
static int hf_3com_xns_type_ethertype;
static int hf_3com_xns_type_retix_bpdu;
static int ett_3com_xns;
static const value_string retix_bpdu_type_vals[] = {
{ 0x0004, "Retix Spanning Tree" },
{ 0, NULL }
};
static dissector_table_t ethertype_subdissector_table;
static dissector_handle_t retix_bpdu_handle;
/*
* Apparently 3Com had some scheme for encapsulating XNS in 802.2 LLC,
* using a DSAP and SSAP of 0x80, and putting a 2-byte field that appeared
* to contain, at least for IPP, the Ethertype value for IPP.
*
* We assume that the value there is an Ethertype value, except for
* the Retix spanning tree protocol, which also uses a DSAP and SSAP
* of 0x80 but has, at least in one capture, 0x0004 as the type
* field. We handle that specially.
*
* XXX - I've also seen packets on 802.11 with a DSAP and SSAP of 0x80,
* but with random stuff that appears neither to be XNS nor Retix
* spanning tree.
*/
static int
dissect_3com_xns(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_tree *subtree;
proto_tree *ti;
uint16_t type;
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "3Com XNS");
col_clear(pinfo->cinfo, COL_INFO);
ti = proto_tree_add_item(tree, proto_3com_xns, tvb, 0, 4, ENC_NA);
subtree = proto_item_add_subtree(ti, ett_3com_xns);
type = tvb_get_ntohs(tvb, 0);
next_tvb = tvb_new_subset_remaining(tvb, 2);
if (type == 0x0004) {
proto_tree_add_uint(subtree, hf_3com_xns_type_retix_bpdu,
tvb, 0, 2, type);
call_dissector(retix_bpdu_handle, next_tvb, pinfo, tree);
} else {
proto_tree_add_uint(subtree, hf_3com_xns_type_ethertype,
tvb, 0, 2, type);
if (!dissector_try_uint(ethertype_subdissector_table,
type, next_tvb, pinfo, tree))
call_data_dissector(next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void
proto_register_3com_xns(void)
{
static hf_register_info hf[] = {
/* registered here but handled in ethertype.c */
{ &hf_3com_xns_type_ethertype,
{ "Type", "3comxns.type", FT_UINT16, BASE_HEX,
VALS(etype_vals), 0x0, NULL, HFILL }},
{ &hf_3com_xns_type_retix_bpdu,
{ "Type", "3comxns.type", FT_UINT16, BASE_HEX,
VALS(retix_bpdu_type_vals), 0x0, NULL, HFILL }},
};
static int *ett[] ={
&ett_3com_xns,
};
proto_3com_xns = proto_register_protocol("3Com XNS Encapsulation", "3COMXNS", "3comxns");
proto_register_field_array(proto_3com_xns, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
our_xns_handle = register_dissector("3comxns", dissect_3com_xns, proto_3com_xns);
}
void
proto_reg_handoff_3com_xns(void)
{
retix_bpdu_handle = find_dissector_add_dependency("rbpdu", proto_3com_xns);
ethertype_subdissector_table = find_dissector_table("ethertype");
dissector_add_uint("llc.dsap", 0x80, our_xns_handle);
}
/*
* 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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