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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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 #include "config.h"
  49
  50 #include <glib.h>
  51 #include <epan/packet.h>
  52 #include <epan/exceptions.h>
  53 #include <epan/etypes.h>
  54 #include <epan/expert.h>
  55 #include <epan/prefs.h>
  56 #include <epan/show_exception.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         void *pd_save;
  81
  82         col_set_str(pinfo->cinfo, COL_PROTOCOL, "CWIDS");
  83         col_set_str(pinfo->cinfo, COL_INFO, "Cwids: ");
  84         /* FIXME: col_set_fence(pinfo->cinfo, all-cols, only addr-cols?); */
  85
  86         cwids_tree = NULL;
  87
  88         while(tvb_length_remaining(tvb, offset) > 0) {
  89                 ti = proto_tree_add_item(tree, proto_cwids, tvb, offset, 28, ENC_NA);
  90                 cwids_tree = proto_item_add_subtree(ti, ett_cwids);
  91
  92                 proto_tree_add_item(cwids_tree, hf_cwids_version, tvb, offset, 2, ENC_BIG_ENDIAN);
  93                 offset += 2;
  94                 proto_tree_add_item(cwids_tree, hf_cwids_unknown1, tvb, offset, 7, ENC_NA);
  95                 offset += 7;
  96                 proto_tree_add_item(cwids_tree, hf_cwids_channel, tvb, offset, 1, ENC_BIG_ENDIAN);
  97                 offset += 1;
  98                 proto_tree_add_item(cwids_tree, hf_cwids_unknown2, tvb, offset, 6, ENC_NA);
  99                 offset += 6;
 100                 proto_tree_add_item(cwids_tree, hf_cwids_reallength, tvb, offset, 2, ENC_BIG_ENDIAN);
 101                 offset += 2;
 102                 capturelen = tvb_get_ntohs(tvb, offset);
 103                 proto_tree_add_item(cwids_tree, hf_cwids_capturelen, tvb, offset, 2, ENC_BIG_ENDIAN);
 104                 offset += 2;
 105                 proto_tree_add_item(cwids_tree, hf_cwids_unknown3, tvb, offset, 8, ENC_NA);
 106                 offset += 8;
 107
 108                 wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
 109                 /* Continue after ieee80211 dissection errors */
 110                 pd_save = pinfo->private_data;
 111                 TRY {
 112                         call_dissector(ieee80211_handle, wlan_tvb, pinfo, tree);
 113                 } CATCH_BOUNDS_ERRORS {
 114                         show_exception(wlan_tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE);
 115
 116                         /*  Restore the private_data structure in case one of the
 117                          *  called dissectors modified it (and, due to the exception,
 118                          *  was unable to restore it).
 119                          */
 120                         pinfo->private_data = pd_save;
 121
 122 #if 0
 123         wlan_tvb = tvb_new_subset(tvb, offset, capturelen, capturelen);
 124                         /* FIXME: Why does this throw an exception? */
 125                         proto_tree_add_text(cwids_tree, wlan_tvb, offset, capturelen,
 126                                 "[Malformed or short IEEE80211 subpacket]");
 127 #else
 128                         tvb_new_subset(tvb, offset, capturelen, capturelen);
 129 #endif
 130         ;
 131                 } ENDTRY;
 132
 133                 offset += capturelen;
 134         }
 135 }
 136
 137 void proto_register_cwids(void);
 138 void proto_reg_handoff_cwids(void);
 139
 140 void
 141 proto_register_cwids(void)
 142 {
 143         static hf_register_info hf[] = {
 144                 { &hf_cwids_version,
 145                 { "Capture Version", "cwids.version", FT_UINT16, BASE_DEC, NULL,
 146                         0x0, "Version or format of record", HFILL }},
 147
 148                 { &hf_cwids_unknown1,
 149                 { "Unknown1", "cwids.unknown1", FT_BYTES, BASE_NONE, NULL,
 150                         0x0, "1st Unknown block - timestamp?", HFILL }},
 151
 152                 { &hf_cwids_channel,
 153                 { "Channel", "cwids.channel", FT_UINT8, BASE_DEC, NULL,
 154                         0x0, "Channel for this capture", HFILL }},
 155
 156                 { &hf_cwids_unknown2,
 157                 { "Unknown2", "cwids.unknown2", FT_BYTES, BASE_NONE, NULL,
 158                         0x0, "2nd Unknown block", HFILL }},
 159
 160                 { &hf_cwids_reallength,
 161                 { "Original length", "cwids.reallen", FT_UINT16, BASE_DEC, NULL,
 162                         0x0, "Original num bytes in frame", HFILL }},
 163
 164                 { &hf_cwids_capturelen,
 165                 { "Capture length", "cwids.caplen", FT_UINT16, BASE_DEC, NULL,
 166                         0x0, "Captured bytes in record", HFILL }},
 167
 168                 { &hf_cwids_unknown3,
 169                 { "Unknown3", "cwids.unknown3", FT_BYTES, BASE_NONE, NULL,
 170                         0x0, "3rd Unknown block", HFILL }},
 171
 172         };
 173         static gint *ett[] = {
 174                 &ett_cwids,
 175         };
 176
 177         module_t *cwids_module;
 178
 179         proto_cwids = proto_register_protocol("Cisco Wireless IDS Captures", "CWIDS", "cwids");
 180         proto_register_field_array(proto_cwids, hf, array_length(hf));
 181         proto_register_subtree_array(ett, array_length(ett));
 182
 183         cwids_module = prefs_register_protocol(proto_cwids, proto_reg_handoff_cwids);
 184         prefs_register_uint_preference(cwids_module, "udp.port",
 185                 "CWIDS port",
 186                 "Set the destination UDP port Cisco wireless IDS messages",
 187                 10, &global_udp_port);
 188
 189 }
 190
 191 void
 192 proto_reg_handoff_cwids(void)
 193 {
 194         static dissector_handle_t cwids_handle;
 195         static guint saved_udp_port;
 196         static gboolean initialized = FALSE;
 197
 198         if (!initialized) {
 199                 cwids_handle = create_dissector_handle(dissect_cwids, proto_cwids);
 200                 dissector_add_handle("udp.port", cwids_handle);
 201                 ieee80211_handle = find_dissector("wlan");
 202                 initialized = TRUE;
 203         } else {
 204                 if (saved_udp_port != 0) {
 205                         dissector_delete_uint("udp.port", saved_udp_port, cwids_handle);
 206                 }
 207         }
 208         if (global_udp_port != 0) {
 209                 dissector_add_uint("udp.port", global_udp_port, cwids_handle);
 210         }
 211         saved_udp_port = global_udp_port;
 212 }
 213