epan/dissectors/packet-cisco-wids.c

   1 /* packet-cwids.c
   2  * Routines for dissecting wireless ids packets sent from a Cisco
   3  * access point to the WLSE (or whatever)
   4  *
   5  * $Id$
   6  *
   7  * Copyright 2006 Joerg Mayer (see AUTHORS file)
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  26  */
  27
  28 /* With current IOS, you can use Cisco wireless Bridges/APs as
  29  * wireless sniffers and configure them to send the data to some
  30  * central IDS:
  31  * interface dot11Radio 0
  32  *   station-role scanner
  33  *   monitor frames endpoint ip address 172.22.1.1 port 8999 truncate 2312
  34  * These frames are raw, i.e. they don't have a pcap header.
  35  * Running wireshark at the receiving end will provide those.
  36  */
  37
  38 /* 2do:
  39  *      - Find out more about the contents of the capture header
  40  *      - Protect the address fields etc (all columns?)
  41  *      - Create subelements and put each header and packet into it
  42  *      - fuzz-test the dissector
  43  *      - Find some heuristic to detect the packet automagically and
  44  *        convert dissector into a heuristic dissector
  45  *      - Is the TRY/CATCH stuff OK?
  46  */
  47
  48 #ifdef HAVE_CONFIG_H
  49 # include "config.h"
  50 #endif
  51
  52 #include <glib.h>
  53 #include <epan/packet.h>
  54 #include <epan/etypes.h>
  55 #include <epan/expert.h>
  56 #include <epan/prefs.h>
  57
  58 static guint global_udp_port = 0;
  59
  60 static int proto_cwids = -1;
  61 static int hf_cwids_version = -1;
  62 static int hf_cwids_unknown1 = -1;
  63 static int hf_cwids_channel = -1;
  64 static int hf_cwids_unknown2 = -1;
  65 static int hf_cwids_reallength = -1;
  66 static int hf_cwids_capturelen = -1;
  67 static int hf_cwids_unknown3 = -1;
  68
  69 static gint ett_cwids = -1;
  70
  71 static dissector_handle_t ieee80211_handle;
  72
  73 static void
  74 dissect_cwids(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  75 {
  76         tvbuff_t *wlan_tvb;
  77         proto_tree *ti, *cwids_tree;
  78         volatile int offset = 0;
  79         guint16 capturelen;
  80         guint remain;
  81
  82         col_set_str(pinfo->cinfo, COL_PROTOCOL, "CWIDS");
  83         if (check_col(pinfo->cinfo, COL_INFO))
  84           col_clear(pinfo->cinfo, COL_INFO);
  85
  86         if (check_col(pinfo->cinfo, COL_INFO)) {
  87           col_set_str(pinfo->cinfo, COL_INFO, "Cwids: ");
  88         }
  89         /* FIXME: col_set_fence(pinfo->cinfo, all-cols, only addr-cols?); */
  90
  91         cwids_tree = NULL;
  92
  93         while((remain = tvb_length_remaining(tvb, offset)) > 0) {
  94                 ti = proto_tree_add_item(tree, proto_cwids, tvb, offset, 28, FALSE);
  95                 cwids_tree = proto_item_add_subtree(ti, ett_cwids);
  96
  97                 proto_tree_add_item(cwids_tree, hf_cwids_version, tvb, offset, 2, FALSE);
  98                 offset += 2;
  99                 proto_tree_add_item(cwids_tree, hf_cwids_unknown1, tvb, offset, 7, FALSE);
 100                 offset += 7;
 101                 proto_tree_add_item(cwids_tree, hf_cwids_channel, tvb, offset, 1, FALSE);
 102                 offset += 1;
 103                 proto_tree_add_item(cwids_tree, hf_cwids_unknown2, tvb, offset, 6, FALSE);
 104                 offset += 6;
 105                 proto_tree_add_item(cwids_tree, hf_cwids_reallength, tvb, offset, 2, FALSE);
 106                 offset += 2;
 107                 capturelen = tvb_get_ntohs(tvb, offset);
 108                 proto_tree_add_item(cwids_tree, hf_cwids_capturelen, tvb, offset, 2, FALSE);
 109                 offset += 2;
 110                 proto_tree_add_item(cwids_tree, hf_cwids_unknown3, tvb, offset, 8, FALSE);
 111                 offset += 8;
 112
 113                 wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
 114                 /* Continue after ieee80211 dissection errors */
 115                 TRY {
 116                         call_dissector(ieee80211_handle, wlan_tvb, pinfo, tree);
 117                 } CATCH2(BoundsError, ReportedBoundsError) {
 118
 119                         expert_add_info_format(pinfo, NULL,
 120                                 PI_MALFORMED, PI_ERROR,
 121                                 "Malformed or short IEEE80211 subpacket");
 122
 123                         if (check_col(pinfo->cinfo, COL_INFO)) {
 124                                 col_append_str(pinfo->cinfo, COL_INFO,
 125                                         " [Malformed or short IEEE80211 subpacket] " );
 126                                 col_set_fence(pinfo->cinfo, COL_INFO);
 127                         }
 128
 129         wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
 130 #if 0
 131                         /* FIXME: Why does this throw an exception? */
 132                         proto_tree_add_text(cwids_tree, wlan_tvb, offset, capturelen,
 133                                 "[Malformed or short IEEE80211 subpacket]");
 134 #endif
 135         ;
 136                 } ENDTRY;
 137
 138                 offset += capturelen;
 139         }
 140 }
 141
 142 void proto_register_cwids(void);
 143 void proto_reg_handoff_cwids(void);
 144
 145 void
 146 proto_register_cwids(void)
 147 {
 148         static hf_register_info hf[] = {
 149                 { &hf_cwids_version,
 150                 { "Capture Version", "cwids.version", FT_UINT16, BASE_DEC, NULL,
 151                         0x0, "Version or format of record", HFILL }},
 152
 153                 { &hf_cwids_unknown1,
 154                 { "Unknown1", "cwids.unknown1", FT_BYTES, BASE_NONE, NULL,
 155                         0x0, "1st Unknown block - timestamp?", HFILL }},
 156
 157                 { &hf_cwids_channel,
 158                 { "Channel", "cwids.channel", FT_UINT8, BASE_DEC, NULL,
 159                         0x0, "Channel for this capture", HFILL }},
 160
 161                 { &hf_cwids_unknown2,
 162                 { "Unknown2", "cwids.unknown2", FT_BYTES, BASE_NONE, NULL,
 163                         0x0, "2nd Unknown block", HFILL }},
 164
 165                 { &hf_cwids_reallength,
 166                 { "Original length", "cwids.reallen", FT_UINT16, BASE_DEC, NULL,
 167                         0x0, "Original num bytes in frame", HFILL }},
 168
 169                 { &hf_cwids_capturelen,
 170                 { "Capture length", "cwids.caplen", FT_UINT16, BASE_DEC, NULL,
 171                         0x0, "Captured bytes in record", HFILL }},
 172
 173                 { &hf_cwids_unknown3,
 174                 { "Unknown3", "cwids.unknown3", FT_BYTES, BASE_NONE, NULL,
 175                         0x0, "3rd Unknown block", HFILL }},
 176
 177         };
 178         static gint *ett[] = {
 179                 &ett_cwids,
 180         };
 181
 182         module_t *cwids_module;
 183
 184         proto_cwids = proto_register_protocol("Cisco Wireless IDS Captures", "CWIDS", "cwids");
 185         proto_register_field_array(proto_cwids, hf, array_length(hf));
 186         proto_register_subtree_array(ett, array_length(ett));
 187
 188         cwids_module = prefs_register_protocol(proto_cwids, proto_reg_handoff_cwids);
 189         prefs_register_uint_preference(cwids_module, "udp.port",
 190                 "CWIDS port",
 191                 "Set the destination UDP port Cisco wireless IDS messages",
 192                 10, &global_udp_port);
 193
 194 }
 195
 196 void
 197 proto_reg_handoff_cwids(void)
 198 {
 199         static dissector_handle_t cwids_handle;
 200         static guint saved_udp_port;
 201         static gboolean initialized = FALSE;
 202
 203         if (!initialized) {
 204                 cwids_handle = create_dissector_handle(dissect_cwids, proto_cwids);
 205                 dissector_add_handle("udp.port", cwids_handle);
 206                 ieee80211_handle = find_dissector("wlan");
 207                 initialized = TRUE;
 208         } else {
 209                 if (saved_udp_port != 0) {
 210                         dissector_delete("udp.port", saved_udp_port, cwids_handle);
 211                 }
 212         }
 213         if (global_udp_port != 0) {
 214                 dissector_add("udp.port", global_udp_port, cwids_handle);
 215         }
 216         saved_udp_port = global_udp_port;
 217 }
 218