129 lines
3.5 KiB
C
129 lines
3.5 KiB
C
/* packet-xns-llc.c
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* Routines for 3Com's encapsulation of XNS over 802.2 LLC
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* (and other protocols using DSAP 80)
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/etypes.h>
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/* Forward declarations */
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void proto_register_3com_xns(void);
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void proto_reg_handoff_3com_xns(void);
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static int proto_3com_xns = -1;
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static int hf_3com_xns_type_ethertype = -1;
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static int hf_3com_xns_type_retix_bpdu = -1;
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static gint ett_3com_xns = -1;
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static const value_string retix_bpdu_type_vals[] = {
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{ 0x0004, "Retix Spanning Tree" },
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{ 0, NULL }
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};
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static dissector_table_t ethertype_subdissector_table;
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static dissector_handle_t retix_bpdu_handle;
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/*
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* Apparently 3Com had some scheme for encapsulating XNS in 802.2 LLC,
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* using a DSAP and SSAP of 0x80, and putting a 2-byte field that appeared
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* to contain, at least for IPP, the Ethertype value for IPP.
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*
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* We assume that the value there is an Ethertype value, except for
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* the Retix spanning tree protocol, which also uses a DSAP and SSAP
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* of 0x80 but has, at least in one capture, 0x0004 as the type
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* field. We handle that specially.
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*
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* XXX - I've also seen packets on 802.11 with a DSAP and SSAP of 0x80,
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* but with random stuff that appears neither to be XNS nor Retix
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* spanning tree.
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*/
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static int
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dissect_3com_xns(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
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{
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proto_tree *subtree;
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proto_tree *ti;
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guint16 type;
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tvbuff_t *next_tvb;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "3Com XNS");
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col_clear(pinfo->cinfo, COL_INFO);
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ti = proto_tree_add_item(tree, proto_3com_xns, tvb, 0, 4, ENC_NA);
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subtree = proto_item_add_subtree(ti, ett_3com_xns);
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type = tvb_get_ntohs(tvb, 0);
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next_tvb = tvb_new_subset_remaining(tvb, 2);
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if (type == 0x0004) {
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proto_tree_add_uint(subtree, hf_3com_xns_type_retix_bpdu,
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tvb, 0, 2, type);
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call_dissector(retix_bpdu_handle, next_tvb, pinfo, tree);
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} else {
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proto_tree_add_uint(subtree, hf_3com_xns_type_ethertype,
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tvb, 0, 2, type);
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if (!dissector_try_uint(ethertype_subdissector_table,
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type, next_tvb, pinfo, tree))
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call_data_dissector(next_tvb, pinfo, tree);
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}
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return tvb_captured_length(tvb);
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}
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void
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proto_register_3com_xns(void)
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{
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static hf_register_info hf[] = {
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/* registered here but handled in ethertype.c */
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{ &hf_3com_xns_type_ethertype,
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{ "Type", "3comxns.type", FT_UINT16, BASE_HEX,
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VALS(etype_vals), 0x0, NULL, HFILL }},
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{ &hf_3com_xns_type_retix_bpdu,
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{ "Type", "3comxns.type", FT_UINT16, BASE_HEX,
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VALS(retix_bpdu_type_vals), 0x0, NULL, HFILL }},
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};
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static gint *ett[] ={
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&ett_3com_xns,
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};
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proto_3com_xns = proto_register_protocol("3Com XNS Encapsulation", "3COMXNS", "3comxns");
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proto_register_field_array(proto_3com_xns, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_3com_xns(void)
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{
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dissector_handle_t our_xns_handle;
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retix_bpdu_handle = find_dissector_add_dependency("rbpdu", proto_3com_xns);
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ethertype_subdissector_table = find_dissector_table("ethertype");
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our_xns_handle = create_dissector_handle(dissect_3com_xns, proto_3com_xns);
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dissector_add_uint("llc.dsap", 0x80, our_xns_handle);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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