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  * Copyright 2006 Joerg Mayer (see AUTHORS file)
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  24  */
  25
  26 /* With current IOS, you can use Cisco wireless Bridges/APs as
  27  * wireless sniffers and configure them to send the data to some
  28  * central IDS:
  29  * interface dot11Radio 0
  30  *   station-role scanner
  31  *   monitor frames endpoint ip address 172.22.1.1 port 8999 truncate 2312
  32  * These frames are raw, i.e. they don't have a pcap header.
  33  * Running wireshark at the receiving end will provide those.
  34  */
  35
  36 /* 2do:
  37  *      - Find out more about the contents of the capture header
  38  *      - Protect the address fields etc (all columns?)
  39  *      - Create subelements and put each header and packet into it
  40  *      - fuzz-test the dissector
  41  *      - Find some heuristic to detect the packet automagically and
  42  *        convert dissector into a heuristic dissector
  43  *      - Is the TRY/CATCH stuff OK?
  44  */
  45
  46 #include "config.h"
  47
  48 #include <glib.h>
  49 #include <epan/packet.h>
  50 #include <epan/exceptions.h>
  51 #include <epan/etypes.h>
  52 #include <epan/expert.h>
  53 #include <epan/prefs.h>
  54 #include <epan/show_exception.h>
  55
  56 static guint global_udp_port = 0;
  57
  58 static int proto_cwids = -1;
  59 static int hf_cwids_version = -1;
  60 static int hf_cwids_unknown1 = -1;
  61 static int hf_cwids_channel = -1;
  62 static int hf_cwids_unknown2 = -1;
  63 static int hf_cwids_reallength = -1;
  64 static int hf_cwids_capturelen = -1;
  65 static int hf_cwids_unknown3 = -1;
  66
  67 static gint ett_cwids = -1;
  68
  69 static dissector_handle_t ieee80211_handle;
  70
  71 static void
  72 dissect_cwids(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  73 {
  74         tvbuff_t *wlan_tvb;
  75         proto_tree *ti, *cwids_tree;
  76         volatile int offset = 0;
  77         guint16 capturelen;
  78         void *pd_save;
  79
  80         col_set_str(pinfo->cinfo, COL_PROTOCOL, "CWIDS");
  81         col_set_str(pinfo->cinfo, COL_INFO, "Cwids: ");
  82         /* FIXME: col_set_fence(pinfo->cinfo, all-cols, only addr-cols?); */
  83
  84         cwids_tree = NULL;
  85
  86         while(tvb_length_remaining(tvb, offset) > 0) {
  87                 ti = proto_tree_add_item(tree, proto_cwids, tvb, offset, 28, ENC_NA);
  88                 cwids_tree = proto_item_add_subtree(ti, ett_cwids);
  89
  90                 proto_tree_add_item(cwids_tree, hf_cwids_version, tvb, offset, 2, ENC_BIG_ENDIAN);
  91                 offset += 2;
  92                 proto_tree_add_item(cwids_tree, hf_cwids_unknown1, tvb, offset, 7, ENC_NA);
  93                 offset += 7;
  94                 proto_tree_add_item(cwids_tree, hf_cwids_channel, tvb, offset, 1, ENC_BIG_ENDIAN);
  95                 offset += 1;
  96                 proto_tree_add_item(cwids_tree, hf_cwids_unknown2, tvb, offset, 6, ENC_NA);
  97                 offset += 6;
  98                 proto_tree_add_item(cwids_tree, hf_cwids_reallength, tvb, offset, 2, ENC_BIG_ENDIAN);
  99                 offset += 2;
 100                 capturelen = tvb_get_ntohs(tvb, offset);
 101                 proto_tree_add_item(cwids_tree, hf_cwids_capturelen, tvb, offset, 2, ENC_BIG_ENDIAN);
 102                 offset += 2;
 103                 proto_tree_add_item(cwids_tree, hf_cwids_unknown3, tvb, offset, 8, ENC_NA);
 104                 offset += 8;
 105
 106                 wlan_tvb = tvb_new_subset_length(tvb, offset, capturelen);
 107                 /* Continue after ieee80211 dissection errors */
 108                 pd_save = pinfo->private_data;
 109                 TRY {
 110                         call_dissector(ieee80211_handle, wlan_tvb, pinfo, tree);
 111                 } CATCH_BOUNDS_ERRORS {
 112                         show_exception(wlan_tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE);
 113
 114                         /*  Restore the private_data structure in case one of the
 115                          *  called dissectors modified it (and, due to the exception,
 116                          *  was unable to restore it).
 117                          */
 118                         pinfo->private_data = pd_save;
 119
 120 #if 0
 121         wlan_tvb = tvb_new_subset_length(tvb, offset, capturelen);
 122                         /* FIXME: Why does this throw an exception? */
 123                         proto_tree_add_text(cwids_tree, wlan_tvb, offset, capturelen,
 124                                 "[Malformed or short IEEE80211 subpacket]");
 125 #else
 126                         tvb_new_subset_length(tvb, offset, capturelen);
 127 #endif
 128         ;
 129                 } ENDTRY;
 130
 131                 offset += capturelen;
 132         }
 133 }
 134
 135 void proto_register_cwids(void);
 136 void proto_reg_handoff_cwids(void);
 137
 138 void
 139 proto_register_cwids(void)
 140 {
 141         static hf_register_info hf[] = {
 142                 { &hf_cwids_version,
 143                 { "Capture Version", "cwids.version", FT_UINT16, BASE_DEC, NULL,
 144                         0x0, "Version or format of record", HFILL }},
 145
 146                 { &hf_cwids_unknown1,
 147                 { "Unknown1", "cwids.unknown1", FT_BYTES, BASE_NONE, NULL,
 148                         0x0, "1st Unknown block - timestamp?", HFILL }},
 149
 150                 { &hf_cwids_channel,
 151                 { "Channel", "cwids.channel", FT_UINT8, BASE_DEC, NULL,
 152                         0x0, "Channel for this capture", HFILL }},
 153
 154                 { &hf_cwids_unknown2,
 155                 { "Unknown2", "cwids.unknown2", FT_BYTES, BASE_NONE, NULL,
 156                         0x0, "2nd Unknown block", HFILL }},
 157
 158                 { &hf_cwids_reallength,
 159                 { "Original length", "cwids.reallen", FT_UINT16, BASE_DEC, NULL,
 160                         0x0, "Original num bytes in frame", HFILL }},
 161
 162                 { &hf_cwids_capturelen,
 163                 { "Capture length", "cwids.caplen", FT_UINT16, BASE_DEC, NULL,
 164                         0x0, "Captured bytes in record", HFILL }},
 165
 166                 { &hf_cwids_unknown3,
 167                 { "Unknown3", "cwids.unknown3", FT_BYTES, BASE_NONE, NULL,
 168                         0x0, "3rd Unknown block", HFILL }},
 169
 170         };
 171         static gint *ett[] = {
 172                 &ett_cwids,
 173         };
 174
 175         module_t *cwids_module;
 176
 177         proto_cwids = proto_register_protocol("Cisco Wireless IDS Captures", "CWIDS", "cwids");
 178         proto_register_field_array(proto_cwids, hf, array_length(hf));
 179         proto_register_subtree_array(ett, array_length(ett));
 180
 181         cwids_module = prefs_register_protocol(proto_cwids, proto_reg_handoff_cwids);
 182         prefs_register_uint_preference(cwids_module, "udp.port",
 183                 "CWIDS port",
 184                 "Set the destination UDP port Cisco wireless IDS messages",
 185                 10, &global_udp_port);
 186
 187 }
 188
 189 void
 190 proto_reg_handoff_cwids(void)
 191 {
 192         static dissector_handle_t cwids_handle;
 193         static guint saved_udp_port;
 194         static gboolean initialized = FALSE;
 195
 196         if (!initialized) {
 197                 cwids_handle = create_dissector_handle(dissect_cwids, proto_cwids);
 198                 dissector_add_handle("udp.port", cwids_handle);
 199                 ieee80211_handle = find_dissector("wlan_withoutfcs");
 200                 initialized = TRUE;
 201         } else {
 202                 if (saved_udp_port != 0) {
 203                         dissector_delete_uint("udp.port", saved_udp_port, cwids_handle);
 204                 }
 205         }
 206         if (global_udp_port != 0) {
 207                 dissector_add_uint("udp.port", global_udp_port, cwids_handle);
 208         }
 209         saved_udp_port = global_udp_port;
 210 }
 211