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packet-cisco-wids.c
/* packet-cwids.c
 * Routines for dissecting wireless ids packets sent from a Cisco 
 * access point to the WLSE (or whatever)
 *
 * $Id: packet-cisco-wids.c 26185 2008-09-12 16:52:01Z wmeier $
 *
 * Copyright 2006 Joerg Mayer (see AUTHORS file)
 *
 * 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.
 */

/* With current IOS, you can use Cisco wireless Bridges/APs as
 * wireless sniffers and configure them to send the data to some
 * central IDS:
 * interface dot11Radio 0
 *   station-role scanner
 *   monitor frames endpoint ip address 172.22.1.1 port 8999 truncate 2312
 * These frames are raw, i.e. they don't have a pcap header.
 * Running wireshark at the receiving end will provide those.
 */

/* 2do:
 *    - Find out more about the contents of the capture header
 *    - Protect the address fields etc (all columns?)
 *    - Create subelements and put each header and packet into it
 *    - fuzz-test the dissector
 *    - Find some heuristic to detect the packet automagically and
 *      convert dissector into a heuristic dissector
 *    - Is the TRY/CATCH stuff OK?
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <glib.h>
#include <epan/packet.h>
#include <epan/etypes.h>
#include <epan/expert.h>
#include <epan/prefs.h>

static guint global_udp_port = 0;

static int proto_cwids = -1;
static int hf_cwids_version = -1;
static int hf_cwids_unknown1 = -1;
static int hf_cwids_channel = -1;
static int hf_cwids_unknown2 = -1;
static int hf_cwids_reallength = -1;
static int hf_cwids_capturelen = -1;
static int hf_cwids_unknown3 = -1;

static gint ett_cwids = -1;

static dissector_handle_t ieee80211_handle;

static void
dissect_cwids(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
      tvbuff_t *wlan_tvb;
      proto_tree *ti, *cwids_tree;
      volatile int offset = 0;
      guint16 capturelen;
      guint remain;

      if (check_col(pinfo->cinfo, COL_PROTOCOL))
        col_set_str(pinfo->cinfo, COL_PROTOCOL, "CWIDS");
      if (check_col(pinfo->cinfo, COL_INFO))
        col_clear(pinfo->cinfo, COL_INFO);

      if (check_col(pinfo->cinfo, COL_INFO)) {
        col_set_str(pinfo->cinfo, COL_INFO, "Cwids: ");
      }
      /* FIXME: col_set_fence(pinfo->cinfo, all-cols, only addr-cols?); */

      cwids_tree = NULL;

      while((remain = tvb_length_remaining(tvb, offset)) > 0) {
            ti = proto_tree_add_item(tree, proto_cwids, tvb, offset, 28, FALSE);
            cwids_tree = proto_item_add_subtree(ti, ett_cwids);
      
            proto_tree_add_item(cwids_tree, hf_cwids_version, tvb, offset, 2, FALSE);
            offset += 2;
            proto_tree_add_item(cwids_tree, hf_cwids_unknown1, tvb, offset, 7, FALSE);
            offset += 7;
            proto_tree_add_item(cwids_tree, hf_cwids_channel, tvb, offset, 1, FALSE);
            offset += 1;
            proto_tree_add_item(cwids_tree, hf_cwids_unknown2, tvb, offset, 6, FALSE);
            offset += 6;
            proto_tree_add_item(cwids_tree, hf_cwids_reallength, tvb, offset, 2, FALSE);
            offset += 2;
            capturelen = tvb_get_ntohs(tvb, offset);
            proto_tree_add_item(cwids_tree, hf_cwids_capturelen, tvb, offset, 2, FALSE);
            offset += 2;
            proto_tree_add_item(cwids_tree, hf_cwids_unknown3, tvb, offset, 8, FALSE);
            offset += 8;
      
            wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
            /* Continue after ieee80211 dissection errors */
            TRY {
                  call_dissector(ieee80211_handle, wlan_tvb, pinfo, tree);
            } CATCH2(BoundsError, ReportedBoundsError) {

                  expert_add_info_format(pinfo, NULL,
                        PI_MALFORMED, PI_ERROR,
                        "Malformed or short IEEE80211 subpacket");

                  if (check_col(pinfo->cinfo, COL_INFO)) {
                        col_append_str(pinfo->cinfo, COL_INFO,
                              " [Malformed or short IEEE80211 subpacket] " );
                        col_set_fence(pinfo->cinfo, COL_INFO);
                  }

      wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
#if 0
                  /* FIXME: Why does this throw an exception? */
                  proto_tree_add_text(cwids_tree, wlan_tvb, offset, capturelen, 
                        "[Malformed or short IEEE80211 subpacket]");
#endif
      ;
            } ENDTRY;

            offset += capturelen;
      }
}

void proto_register_cwids(void);
void proto_reg_handoff_cwids(void);

void
proto_register_cwids(void)
{
      static hf_register_info hf[] = {
            { &hf_cwids_version,
            { "Capture Version", "cwids.version", FT_UINT16, BASE_DEC, NULL,
                  0x0, "Version or format of record", HFILL }},

            { &hf_cwids_unknown1,
            { "Unknown1", "cwids.unknown1", FT_BYTES, BASE_NONE, NULL,
                  0x0, "1st Unknown block - timestamp?", HFILL }},

            { &hf_cwids_channel,
            { "Channel", "cwids.channel", FT_UINT8, BASE_DEC, NULL,
                  0x0, "Channel for this capture", HFILL }},

            { &hf_cwids_unknown2,
            { "Unknown2", "cwids.unknown2", FT_BYTES, BASE_NONE, NULL,
                  0x0, "2nd Unknown block", HFILL }},

            { &hf_cwids_reallength,
            { "Original length", "cwids.reallen", FT_UINT16, BASE_DEC, NULL,
                  0x0, "Original num bytes in frame", HFILL }},

            { &hf_cwids_capturelen,
            { "Capture length", "cwids.caplen", FT_UINT16, BASE_DEC, NULL,
                  0x0, "Captured bytes in record", HFILL }},

            { &hf_cwids_unknown3,
            { "Unknown3", "cwids.unknown3", FT_BYTES, BASE_NONE, NULL,
                  0x0, "3rd Unknown block", HFILL }},

      };
      static gint *ett[] = {
            &ett_cwids,
      };

      module_t *cwids_module;

      proto_cwids = proto_register_protocol("Cisco Wireless IDS Captures", "CWIDS", "cwids");
      proto_register_field_array(proto_cwids, hf, array_length(hf));
      proto_register_subtree_array(ett, array_length(ett));

      cwids_module = prefs_register_protocol(proto_cwids, proto_reg_handoff_cwids);
      prefs_register_uint_preference(cwids_module, "udp.port",
            "CWIDS port",
            "Set the destination UDP port Cisco wireless IDS messages",
            10, &global_udp_port);

}

void
proto_reg_handoff_cwids(void)
{
      static dissector_handle_t cwids_handle;
      static guint saved_udp_port;
      static gboolean initialized = FALSE;

      if (!initialized) {
            cwids_handle = create_dissector_handle(dissect_cwids, proto_cwids);
            dissector_add_handle("udp.port", cwids_handle);
            ieee80211_handle = find_dissector("wlan");
            initialized = TRUE;
      } else {
            if (saved_udp_port != 0) {
                  dissector_delete("udp.port", saved_udp_port, cwids_handle);
            }
      }
      if (global_udp_port != 0) {
            dissector_add("udp.port", global_udp_port, cwids_handle);
      }
      saved_udp_port = global_udp_port;
}


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