epan/dissectors/packet-mrdisc.c

   1 /* packet-mrdisc.c   2001 Ronnie Sahlberg <See AUTHORS for email>
   2  * Routines for IGMP/MRDISC 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
  26
  27                         MRDISC
  28         code
  29
  30         0x24            x
  31         0x25            x
  32         0x26            x
  33
  34         MRDISC : IGMP Multicast Router DISCovery
  35         Defined in draft-ietf-idmr-igmp-mrdisc-06.txt
  36         TTL==1 and IP.DST==224.0.0.2 for all packets.
  37 */
  38
  39 #include "config.h"
  40
  41 #include <glib.h>
  42
  43 #include <epan/packet.h>
  44 #include <epan/exceptions.h>
  45
  46 #include "packet-igmp.h"
  47 #include "packet-mrdisc.h"
  48
  49
  50 static int proto_mrdisc = -1;
  51 static int hf_checksum = -1;
  52 static int hf_checksum_bad = -1;
  53 static int hf_type = -1;
  54 static int hf_advint = -1;
  55 static int hf_numopts = -1;
  56 static int hf_options = -1;
  57 static int hf_option = -1;
  58 static int hf_option_len = -1;
  59 static int hf_qi = -1;
  60 static int hf_rv = -1;
  61 static int hf_option_bytes = -1;
  62
  63 static int ett_mrdisc = -1;
  64 static int ett_options = -1;
  65
  66 #define MRDISC_MRA      0x24
  67 #define MRDISC_MRS      0x25
  68 #define MRDISC_MRT      0x26
  69 static const value_string mrdisc_types[] = {
  70         {MRDISC_MRA,    "Multicast Router Advertisement"},
  71         {MRDISC_MRS,    "Multicast Router Solicitation"},
  72         {MRDISC_MRT,    "Multicast Router Termination"},
  73         {0,                                     NULL}
  74 };
  75
  76 #define MRDISC_QI       0x01
  77 #define MRDISC_RV       0x02
  78 static const value_string mrdisc_options[] = {
  79         {MRDISC_QI,     "Query Interval"},
  80         {MRDISC_RV,     "Robustness Variable"},
  81         {0,                                     NULL}
  82 };
  83
  84
  85 static int
  86 dissect_mrdisc_mra(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
  87 {
  88         guint16 num;
  89
  90         /* Advertising Interval */
  91         proto_tree_add_item(parent_tree, hf_advint, tvb, offset, 1, ENC_BIG_ENDIAN);
  92         offset += 1;
  93
  94         /* checksum */
  95         igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_bad, pinfo, 0);
  96         offset += 2;
  97
  98         /* skip unused bytes */
  99         offset += 2;
 100
 101         /* number of options */
 102         num = tvb_get_ntohs(tvb, offset);
 103         proto_tree_add_uint(parent_tree, hf_numopts, tvb,
 104                 offset, 2, num);
 105         offset += 2;
 106
 107         /* process any options */
 108         while (num--) {
 109                 proto_tree *tree;
 110                 proto_item *item;
 111                 guint8 type,len;
 112                 int old_offset = offset;
 113
 114                 item = proto_tree_add_item(parent_tree, hf_options,
 115                         tvb, offset, -1, ENC_NA);
 116                 tree = proto_item_add_subtree(item, ett_options);
 117
 118                 type = tvb_get_guint8(tvb, offset);
 119                 proto_tree_add_uint(tree, hf_option, tvb, offset, 1, type);
 120                 offset += 1;
 121
 122                 len = tvb_get_guint8(tvb, offset);
 123                 proto_tree_add_uint(tree, hf_option_len, tvb, offset, 1, len);
 124                 offset += 1;
 125
 126                 switch (type) {
 127                 case MRDISC_QI:
 128                         if (item) {
 129                                 proto_item_set_text(item,"Option: %s == %d",
 130                                         val_to_str(type, mrdisc_options, "unknown %x"),
 131                                         tvb_get_ntohs(tvb, offset));
 132                         }
 133
 134                         if (len != 2)
 135                                 THROW(ReportedBoundsError);
 136                         proto_tree_add_item(tree, hf_qi, tvb, offset, len,
 137                                 ENC_BIG_ENDIAN);
 138                         offset += len;
 139                         break;
 140                 case MRDISC_RV:
 141                         if (item) {
 142                                 proto_item_set_text(item,"Option: %s == %d",
 143                                         val_to_str(type, mrdisc_options, "unknown %x"),
 144                                         tvb_get_ntohs(tvb, offset));
 145                         }
 146
 147                         if (len != 2)
 148                                 THROW(ReportedBoundsError);
 149                         proto_tree_add_item(tree, hf_rv, tvb, offset, len,
 150                                 ENC_BIG_ENDIAN);
 151                         offset += len;
 152                         break;
 153                 default:
 154                         if (item) {
 155                                 proto_item_set_text(item,"Option: unknown");
 156                         }
 157
 158                         proto_tree_add_item(tree, hf_option_bytes,
 159                                 tvb, offset, len, ENC_NA);
 160                         offset += len;
 161                 }
 162                 if (item) {
 163                         proto_item_set_len(item, offset-old_offset);
 164                 }
 165         }
 166
 167         return offset;
 168 }
 169
 170
 171 static int
 172 dissect_mrdisc_mrst(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
 173 {
 174         /* skip reserved byte */
 175         offset += 1;
 176
 177         /* checksum */
 178         igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_bad, pinfo, 0);
 179         offset += 2;
 180
 181         return offset;
 182 }
 183
 184
 185 /* This function is only called from the IGMP dissector */
 186 int
 187 dissect_mrdisc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
 188 {
 189         proto_tree *tree;
 190         proto_item *item;
 191         guint8 type;
 192
 193         if (!proto_is_protocol_enabled(find_protocol_by_id(proto_mrdisc))) {
 194                 /* we are not enabled, skip entire packet to be nice
 195                    to the igmp layer. (so clicking on IGMP will display the data)
 196                  */
 197                 return offset+tvb_length_remaining(tvb, offset);
 198         }
 199
 200         item = proto_tree_add_item(parent_tree, proto_mrdisc, tvb, offset, 0, ENC_NA);
 201         tree = proto_item_add_subtree(item, ett_mrdisc);
 202
 203
 204         col_set_str(pinfo->cinfo, COL_PROTOCOL, "MRDISC");
 205         col_clear(pinfo->cinfo, COL_INFO);
 206
 207
 208         type = tvb_get_guint8(tvb, offset);
 209         col_add_str(pinfo->cinfo, COL_INFO,
 210                         val_to_str(type, mrdisc_types,
 211                                 "Unknown Type:0x%02x"));
 212
 213         /* type of command */
 214         proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);
 215         offset += 1;
 216
 217         switch (type) {
 218         case MRDISC_MRA:
 219                 offset = dissect_mrdisc_mra(tvb, pinfo, tree, offset);
 220                 break;
 221         case MRDISC_MRS:
 222         case MRDISC_MRT:
 223                 /* MRS and MRT packets looks the same */
 224                 offset = dissect_mrdisc_mrst(tvb, pinfo, tree, offset);
 225                 break;
 226         }
 227         return offset;
 228 }
 229
 230
 231 void
 232 proto_register_mrdisc(void)
 233 {
 234         static hf_register_info hf[] = {
 235                 { &hf_type,
 236                         { "Type", "mrdisc.type", FT_UINT8, BASE_HEX,
 237                           VALS(mrdisc_types), 0, "MRDISC Packet Type", HFILL }},
 238
 239                 { &hf_checksum,
 240                         { "Checksum", "mrdisc.checksum", FT_UINT16, BASE_HEX,
 241                           NULL, 0, "MRDISC Checksum", HFILL }},
 242
 243                 { &hf_checksum_bad,
 244                         { "Bad Checksum", "mrdisc.checksum_bad", FT_BOOLEAN, BASE_NONE,
 245                           NULL, 0x0, "Bad MRDISC Checksum", HFILL }},
 246
 247                 { &hf_advint,
 248                         { "Advertising Interval", "mrdisc.adv_int", FT_UINT8, BASE_DEC,
 249                           NULL, 0, "MRDISC Advertising Interval in seconds", HFILL }},
 250
 251                 { &hf_numopts,
 252                         { "Number Of Options", "mrdisc.num_opts", FT_UINT16, BASE_DEC,
 253                           NULL, 0, "MRDISC Number Of Options", HFILL }},
 254
 255                 { &hf_options,
 256                         { "Options", "mrdisc.options", FT_NONE, BASE_NONE,
 257                           NULL, 0, "MRDISC Options", HFILL }},
 258
 259                 { &hf_option,
 260                         { "Option", "mrdisc.option", FT_UINT8, BASE_DEC,
 261                           VALS(mrdisc_options), 0, "MRDISC Option Type", HFILL }},
 262
 263                 { &hf_option_len,
 264                         { "Length", "mrdisc.opt_len", FT_UINT8, BASE_DEC,
 265                           NULL, 0, "MRDISC Option Length", HFILL }},
 266
 267                 { &hf_qi,
 268                         { "Query Interval", "mrdisc.query_int", FT_UINT16, BASE_DEC,
 269                           NULL, 0, "MRDISC Query Interval", HFILL }},
 270
 271                 { &hf_rv,
 272                         { "Robustness Variable", "mrdisc.rob_var", FT_UINT16, BASE_DEC,
 273                           NULL, 0, "MRDISC Robustness Variable", HFILL }},
 274
 275                 { &hf_option_bytes,
 276                         { "Data", "mrdisc.option_data", FT_BYTES, BASE_NONE,
 277                           NULL, 0, "MRDISC Unknown Option Data", HFILL }},
 278
 279         };
 280         static gint *ett[] = {
 281                 &ett_mrdisc,
 282                 &ett_options,
 283         };
 284
 285         proto_mrdisc = proto_register_protocol("Multicast Router DISCovery protocol",
 286             "MRDISC", "mrdisc");
 287         proto_register_field_array(proto_mrdisc, hf, array_length(hf));
 288         proto_register_subtree_array(ett, array_length(ett));
 289 }