epan/dissectors/packet-isdn.c

   1 /* packet-isdn.c
   2  * Routines for ISDN packet disassembly
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include <glib.h>
  28 #include <epan/packet.h>
  29 #include <epan/prefs.h>
  30 #include <epan/circuit.h>
  31
  32 static int proto_isdn = -1;
  33 static int hf_isdn_channel = -1;
  34
  35 static gint ett_isdn = -1;
  36
  37 /*
  38  * Protocol used on the D channel.
  39  */
  40 #define DCHANNEL_LAPD   0       /* LAPD */
  41 #define DCHANNEL_DPNSS  1       /* DPNSS link layer */
  42
  43 static const enum_val_t dchannel_protocol_options[] = {
  44     { "lapd", "LAPD", DCHANNEL_LAPD },
  45     { "DPNSS", "DPNSS", DCHANNEL_DPNSS },
  46     { NULL, NULL, 0 }
  47 };
  48
  49 static int dchannel_protocol = DCHANNEL_LAPD;
  50
  51 static dissector_handle_t lapd_handle;
  52 static dissector_handle_t dpnss_link_handle;
  53 static dissector_handle_t ppp_hdlc_handle;
  54 static dissector_handle_t v120_handle;
  55 static dissector_handle_t data_handle;
  56
  57 static const value_string channel_vals[] = {
  58         { 0,    "D" },
  59         { 1,    "B1" },
  60         { 2,    "B2" },
  61         { 3,    "B3" },
  62         { 4,    "B4" },
  63         { 5,    "B5" },
  64         { 6,    "B6" },
  65         { 7,    "B7" },
  66         { 8,    "B8" },
  67         { 9,    "B9" },
  68         { 10,   "B10" },
  69         { 11,   "B11" },
  70         { 12,   "B12" },
  71         { 13,   "B13" },
  72         { 14,   "B14" },
  73         { 15,   "B15" },
  74         { 16,   "B16" },
  75         { 17,   "B17" },
  76         { 18,   "B19" },
  77         { 19,   "B19" },
  78         { 20,   "B20" },
  79         { 21,   "B21" },
  80         { 22,   "B22" },
  81         { 23,   "B23" },
  82         { 24,   "B24" },
  83         { 25,   "B25" },
  84         { 26,   "B26" },
  85         { 27,   "B27" },
  86         { 28,   "B29" },
  87         { 29,   "B29" },
  88         { 30,   "B30" },
  89         { 0,    NULL }
  90 };
  91
  92 static void
  93 dissect_isdn(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  94 {
  95         proto_tree *isdn_tree;
  96         proto_item *ti;
  97         static const guint8 v120_sabme[3] = { 0x08, 0x01, 0x7F };
  98         static const guint8 ppp[2] = { 0xFF, 0x03 };
  99         circuit_t *circuit;
 100
 101         col_set_str(pinfo->cinfo, COL_PROTOCOL, "ISDN");
 102
 103         if (pinfo->pseudo_header->isdn.uton) {
 104                 col_set_str(pinfo->cinfo, COL_RES_DL_DST, "Network");
 105                 col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "User");
 106         } else {
 107                 col_set_str(pinfo->cinfo, COL_RES_DL_DST, "User");
 108                 col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "Network");
 109         }
 110
 111         pinfo->ctype = CT_ISDN;
 112         pinfo->circuit_id = pinfo->pseudo_header->isdn.channel;
 113
 114         if (tree) {
 115                 ti = proto_tree_add_item(tree, proto_isdn, tvb, 0, 0, ENC_NA);
 116                 isdn_tree = proto_item_add_subtree(ti, ett_isdn);
 117
 118                 proto_tree_add_uint(isdn_tree, hf_isdn_channel, tvb, 0, 0,
 119                     pinfo->pseudo_header->isdn.channel);
 120         }
 121
 122         /*
 123          * Set up a circuit for this channel, and assign it a dissector.
 124          */
 125         circuit = find_circuit(pinfo->ctype, pinfo->circuit_id, pinfo->fd->num);
 126         if (circuit == NULL)
 127                 circuit = circuit_new(pinfo->ctype, pinfo->circuit_id,
 128                     pinfo->fd->num);
 129
 130         if (circuit_get_dissector(circuit) == NULL) {
 131                 /*
 132                  * We don't yet know the type of traffic on the circuit.
 133                  */
 134                 switch (pinfo->pseudo_header->isdn.channel) {
 135
 136                 case 0:
 137                         /*
 138                          * D-channel.  Dissect it with whatever protocol
 139                          * the user specified, or the default of LAPD if
 140                          * they didn't specify one.
 141                          */
 142                         switch (dchannel_protocol) {
 143
 144                         case DCHANNEL_LAPD:
 145                                 circuit_set_dissector(circuit, lapd_handle);
 146                                 break;
 147
 148                         case DCHANNEL_DPNSS:
 149                                 circuit_set_dissector(circuit,
 150                                     dpnss_link_handle);
 151                                 break;
 152                         }
 153                         break;
 154
 155                 default:
 156                         /*
 157                          * B-channel.
 158                          *
 159                          * We don't know yet whether the datastream is
 160                          * V.120 or not; this heuristic tries to figure
 161                          * that out.
 162                          *
 163                          * We cannot glean this from the Q.931 SETUP message,
 164                          * because no commercial V.120 implementation I've
 165                          * seen actually sets the V.120 protocol discriminator
 166                          * (that, or I'm misreading the spec badly).
 167                          *
 168                          * TODO: close the circuit after a close on the B
 169                          * channel is detected.
 170                          *
 171                          *      -Bert Driehuis (from the i4btrace reader;
 172                          *       this heuristic was moved from there to
 173                          *       here)
 174                          *
 175                          * XXX - I don't know that one can guarantee that
 176                          * the SABME will appear in the first frame on
 177                          * the channels, so we probably can't just say
 178                          * "it must be PPP" if we don't immediately see
 179                          * the V.120 SABME frame, so we do so only if
 180                          * we see the 0xFF 0x03.  Unfortunately, that
 181                          * won't do the right thing if the PPP-over-HDLC
 182                          * headers aren't being used....
 183                          */
 184                         if (tvb_memeql(tvb, 0, v120_sabme, 3) == 0) {
 185                                 /*
 186                                  * We assume this is V.120.
 187                                  */
 188                                 circuit_set_dissector(circuit, v120_handle);
 189                         } else if (tvb_memeql(tvb, 0, ppp, 2) == 0) {
 190                                 /*
 191                                  * We assume this is PPP.
 192                                  */
 193                                 circuit_set_dissector(circuit, ppp_hdlc_handle);
 194                         }
 195                         break;
 196                 }
 197         }
 198
 199         if (!try_circuit_dissector(pinfo->ctype, pinfo->circuit_id,
 200                 pinfo->fd->num, tvb, pinfo, tree, NULL))
 201                 call_dissector(data_handle, tvb, pinfo, tree);
 202 }
 203
 204 void
 205 proto_register_isdn(void)
 206 {
 207         static hf_register_info hf[] = {
 208                 { &hf_isdn_channel,
 209                 { "Channel",    "isdn.channel", FT_UINT8, BASE_DEC,
 210                   VALS(channel_vals), 0x0, NULL, HFILL }},
 211         };
 212         static gint *ett[] = {
 213                 &ett_isdn,
 214         };
 215         module_t *isdn_module;
 216
 217         proto_isdn = proto_register_protocol("ISDN", "ISDN", "isdn");
 218         proto_register_field_array(proto_isdn, hf, array_length(hf));
 219         proto_register_subtree_array(ett, array_length(ett));
 220
 221         isdn_module = prefs_register_protocol(proto_isdn, NULL);
 222
 223         prefs_register_enum_preference(isdn_module, "dchannel_protocol",
 224             "D-channel protocol",
 225             "The protocol running on the D channel",
 226             &dchannel_protocol, dchannel_protocol_options, FALSE);
 227 }
 228
 229 void
 230 proto_reg_handoff_isdn(void)
 231 {
 232         dissector_handle_t isdn_handle;
 233
 234         /*
 235          * Get handles for the LAPD, DPNSS link-layer, PPP, and V.120
 236          * dissectors.
 237          */
 238         lapd_handle = find_dissector("lapd");
 239         dpnss_link_handle = find_dissector("dpnss_link");
 240         ppp_hdlc_handle = find_dissector("ppp_hdlc");
 241         v120_handle = find_dissector("v120");
 242         data_handle = find_dissector("data");
 243
 244         isdn_handle = create_dissector_handle(dissect_isdn, proto_isdn);
 245
 246         dissector_add_uint("wtap_encap", WTAP_ENCAP_ISDN, isdn_handle);
 247 }