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packet-cgmp.c

/* packet-cgmp.c
 * Routines for the disassembly of the Cisco Group Management Protocol
 *
 * $Id: packet-cgmp.c 18196 2006-05-21 04:49:01Z sahlberg $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "config.h"

#include <stdlib.h>
#include <string.h>

#include <glib.h>
#include <epan/packet.h>

/*
 * See
 *
 * http://www.barnett.sk/software/bbooks/cisco_multicasting_routing/chap04.html
 *
 * for some information on CGMP.
 */

static int proto_cgmp = -1;
static int hf_cgmp_version = -1;
static int hf_cgmp_type = -1;
static int hf_cgmp_count = -1;
static int hf_cgmp_gda = -1;
static int hf_cgmp_usa = -1;

static gint ett_cgmp = -1;

static const value_string type_vals[] = {
      { 0, "Join" },
      { 1, "Leave" },
      { 0, NULL },
};

static void
dissect_cgmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
      proto_item *ti;
      proto_tree *cgmp_tree = NULL;
      int offset = 0;
      guint8 count;

      if (check_col(pinfo->cinfo, COL_PROTOCOL))
            col_set_str(pinfo->cinfo, COL_PROTOCOL, "CGMP");
      if (check_col(pinfo->cinfo, COL_INFO))
            col_set_str(pinfo->cinfo, COL_INFO, "Cisco Group Management Protocol");

      if (tree) {
            ti = proto_tree_add_item(tree, proto_cgmp, tvb, offset, -1,
                FALSE);
            cgmp_tree = proto_item_add_subtree(ti, ett_cgmp);

            proto_tree_add_item(cgmp_tree, hf_cgmp_version, tvb, offset, 1,
                FALSE);
            proto_tree_add_item(cgmp_tree, hf_cgmp_type, tvb, offset, 1,
                FALSE);
            offset += 1;

            offset += 2;      /* skip reserved field */

            count = tvb_get_guint8(tvb, offset);
            proto_tree_add_uint(cgmp_tree, hf_cgmp_count, tvb, offset, 1,
                count);
            offset += 1;

            while (count != 0) {
                  proto_tree_add_item(cgmp_tree, hf_cgmp_gda, tvb, offset, 6,
                      FALSE);
                  offset += 6;

                  proto_tree_add_item(cgmp_tree, hf_cgmp_usa, tvb, offset, 6,
                      FALSE);
                  offset += 6;

                  count--;
            }
      }
}

void
proto_register_cgmp(void)
{
      static hf_register_info hf[] = {
            { &hf_cgmp_version,
            { "Version",      "cgmp.version",   FT_UINT8, BASE_DEC, NULL, 0xF0,
                  "", HFILL }},

            { &hf_cgmp_type,
            { "Type",   "cgmp.type",      FT_UINT8, BASE_DEC, VALS(type_vals), 0x0F,
                  "", HFILL }},

            { &hf_cgmp_count,
            { "Count",  "cgmp.count", FT_UINT8, BASE_DEC, NULL, 0x0,
                  "", HFILL }},

            { &hf_cgmp_gda,
            { "Group Destination Address",      "cgmp.gda", FT_ETHER, BASE_NONE, NULL, 0x0,
                  "Group Destination Address", HFILL }},

            { &hf_cgmp_usa,
            { "Unicast Source Address",   "cgmp.usa", FT_ETHER, BASE_NONE, NULL, 0x0,
                  "Unicast Source Address", HFILL }},
        };
      static gint *ett[] = {
            &ett_cgmp,
      };

        proto_cgmp = proto_register_protocol("Cisco Group Management Protocol",
          "CGMP", "cgmp");
        proto_register_field_array(proto_cgmp, hf, array_length(hf));
      proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_cgmp(void)
{
      dissector_handle_t cgmp_handle;

      cgmp_handle = create_dissector_handle(dissect_cgmp, proto_cgmp);
      dissector_add("llc.cisco_pid", 0x2001, cgmp_handle);
      dissector_add("ethertype", 0x2001, cgmp_handle);
}

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