![Michael Mann](/assets/img/avatar_default.png)
The main driving force for this was my new Decode As functionality (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=9450) that wants a dissector/subdissector table relationship for all dissectors wanting to use Decode As functionality. The ethertype() function provides the value to the "ethertype" subdissector table, so I think it should be matched to a dissector. Only odd side effect is the display filter of "ethertype" returns no packets because there is no "item" associated with the dissector. svn path=/trunk/; revision=53443
146 lines
4.1 KiB
C
146 lines
4.1 KiB
C
/* packet-vntag.c
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*
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* $Id$
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/etypes.h>
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static dissector_handle_t ethertype_handle;
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static int proto_vntag = -1;
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static int hf_vntag_etype = -1;
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/* static int hf_vntag_len = -1; */
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static int hf_vntag_trailer = -1;
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static gint ett_vntag = -1;
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static void
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dissect_vntag(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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guint16 encap_proto;
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proto_tree *vntag_tree = NULL;
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ethertype_data_t ethertype_data;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "VNTAG");
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col_clear(pinfo->cinfo, COL_INFO);
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if (tree) {
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proto_item *ti = proto_tree_add_item(tree, proto_vntag, tvb, 0, 4, ENC_NA);
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vntag_tree = proto_item_add_subtree(ti, ett_vntag);
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/* XXX, 4 bytes of data */
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/* from scapy (http://hg.secdev.org/scapy-com/rev/37acec891993) GPLv2:
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BitField("dir", 0, 1),
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BitField("ptr", 0, 1),
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BitField("dst", 0, 14),
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BitField("looped", 0, 1),
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BitField("r", 0, 1),
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BitField("version", 0, 2),
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BitField("src", 0, 12) ]
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*/
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/* another: http://www.definethecloud.net/access-layer-network-virtualization-vn-tag-and-vepa */
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}
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encap_proto = tvb_get_ntohs(tvb, 4);
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/* copied from packet-vlan.c do we need it also for VNTAG? */
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#if 0
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if (encap_proto <= IEEE_802_3_MAX_LEN) {
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gboolean is_802_2;
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/* Is there an 802.2 layer? I can tell by looking at the first 2
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bytes after the VLAN header. If they are 0xffff, then what
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follows the VLAN header is an IPX payload, meaning no 802.2.
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(IPX/SPX is they only thing that can be contained inside a
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straight 802.3 packet, so presumably the same applies for
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Ethernet VLAN packets). A non-0xffff value means that there's an
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802.2 layer inside the VLAN layer */
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is_802_2 = TRUE;
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/* Don't throw an exception for this check (even a BoundsError) */
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if (tvb_length_remaining(tvb, 4) >= 2) {
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if (tvb_get_ntohs(tvb, 4) == 0xffff)
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is_802_2 = FALSE;
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}
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dissect_802_3(encap_proto, is_802_2, tvb, 4, pinfo, tree, vntag_tree, hf_vntag_len, hf_vntag_trailer, 0);
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} else {
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#endif
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ethertype_data.etype = encap_proto;
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ethertype_data.offset_after_ethertype = 6;
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ethertype_data.fh_tree = vntag_tree;
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ethertype_data.etype_id = hf_vntag_etype;
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ethertype_data.trailer_id = hf_vntag_trailer;
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ethertype_data.fcs_len = 0;
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call_dissector_with_data(ethertype_handle, tvb, pinfo, tree, ðertype_data);
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#if 0
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}
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#endif
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}
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void
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proto_register_vntag(void)
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{
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static hf_register_info hf[] = {
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{ &hf_vntag_etype,
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{ "Type", "vntag.etype", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0, NULL, HFILL }
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},
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#if 0
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{ &hf_vntag_len,
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{ "Length", "vntag.len", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }
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},
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#endif
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{ &hf_vntag_trailer,
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{ "Trailer", "vntag.trailer", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }
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}
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};
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static gint *ett[] = {
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&ett_vntag
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};
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proto_vntag = proto_register_protocol("VN-Tag", "VNTAG", "vntag");
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proto_register_field_array(proto_vntag, 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_vntag(void)
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{
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dissector_handle_t vntag_handle;
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/* XXX, add 0x8926 define to epan/etypes.h && etype_vals */
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vntag_handle = create_dissector_handle(dissect_vntag, proto_vntag);
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dissector_add_uint("ethertype", 0x8926, vntag_handle);
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ethertype_handle = find_dissector("ethertype");
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}
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