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  * Ethereal - Network traffic analyzer
   7  * By Gerald Combs <gerald@ethereal.com>
   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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, 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 #ifdef HAVE_CONFIG_H
  40 # include "config.h"
  41 #endif
  42
  43 #include <stdio.h>
  44 #include <string.h>
  45 #include <glib.h>
  46
  47 #include <epan/packet.h>
  48 #include "packet-igmp.h"
  49 #include "packet-mrdisc.h"
  50
  51
  52 static int proto_mrdisc = -1;
  53 static int hf_checksum = -1;
  54 static int hf_checksum_bad = -1;
  55 static int hf_type = -1;
  56 static int hf_advint = -1;
  57 static int hf_numopts = -1;
  58 static int hf_options = -1;
  59 static int hf_option = -1;
  60 static int hf_option_len = -1;
  61 static int hf_qi = -1;
  62 static int hf_rv = -1;
  63 static int hf_option_bytes = -1;
  64
  65 static int ett_mrdisc = -1;
  66 static int ett_options = -1;
  67
  68 #define MRDISC_MRA      0x24
  69 #define MRDISC_MRS      0x25
  70 #define MRDISC_MRT      0x26
  71 static const value_string mrdisc_types[] = {
  72         {MRDISC_MRA,    "Multicast Router Advertisement"},
  73         {MRDISC_MRS,    "Multicast Router Solicitation"},
  74         {MRDISC_MRT,    "Multicast Router Termination"},
  75         {0,                                     NULL}
  76 };
  77
  78 #define MRDISC_QI       0x01
  79 #define MRDISC_RV       0x02
  80 static const value_string mrdisc_options[] = {
  81         {MRDISC_QI,     "Query Interval"},
  82         {MRDISC_RV,     "Robustness Variable"},
  83         {0,                                     NULL}
  84 };
  85
  86
  87 static int
  88 dissect_mrdisc_mra(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
  89 {
  90         guint16 num;
  91
  92         /* Advertising Interval */
  93         proto_tree_add_item(parent_tree, hf_advint, tvb, offset, 1, FALSE);
  94         offset += 1;
  95
  96         /* checksum */
  97         igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_bad, pinfo, 0);
  98         offset += 2;
  99
 100         /* skip unused bytes */
 101         offset += 2;
 102
 103         /* number of options */
 104         num = tvb_get_ntohs(tvb, offset);
 105         proto_tree_add_uint(parent_tree, hf_numopts, tvb,
 106                 offset, 2, num);
 107         offset += 2;
 108
 109         /* process any options */
 110         while (num--) {
 111                 proto_tree *tree;
 112                 proto_item *item;
 113                 guint8 type,len;
 114                 int old_offset = offset;
 115
 116                 item = proto_tree_add_item(parent_tree, hf_options,
 117                         tvb, offset, -1, FALSE);
 118                 tree = proto_item_add_subtree(item, ett_options);
 119
 120                 type = tvb_get_guint8(tvb, offset);
 121                 proto_tree_add_uint(tree, hf_option, tvb, offset, 1, type);
 122                 offset += 1;
 123
 124                 len = tvb_get_guint8(tvb, offset);
 125                 proto_tree_add_uint(tree, hf_option_len, tvb, offset, 1, len);
 126                 offset += 1;
 127
 128                 switch (type) {
 129                 case MRDISC_QI:
 130                         if (item) {
 131                                 proto_item_set_text(item,"Option: %s == %d",
 132                                         val_to_str(type, mrdisc_options, "unknown %x"),
 133                                         tvb_get_ntohs(tvb, offset));
 134                         }
 135
 136                         if (len != 2)
 137                                 THROW(ReportedBoundsError);
 138                         proto_tree_add_item(tree, hf_qi, tvb, offset, len,
 139                                 FALSE);
 140                         offset += len;
 141                         break;
 142                 case MRDISC_RV:
 143                         if (item) {
 144                                 proto_item_set_text(item,"Option: %s == %d",
 145                                         val_to_str(type, mrdisc_options, "unknown %x"),
 146                                         tvb_get_ntohs(tvb, offset));
 147                         }
 148
 149                         if (len != 2)
 150                                 THROW(ReportedBoundsError);
 151                         proto_tree_add_item(tree, hf_rv, tvb, offset, len,
 152                                 FALSE);
 153                         offset += len;
 154                         break;
 155                 default:
 156                         if (item) {
 157                                 proto_item_set_text(item,"Option: unknown");
 158                         }
 159
 160                         proto_tree_add_item(tree, hf_option_bytes,
 161                                 tvb, offset, len, FALSE);
 162                         offset += len;
 163                 }
 164                 if (item) {
 165                         proto_item_set_len(item, offset-old_offset);
 166                 }
 167         }
 168
 169         return offset;
 170 }
 171
 172
 173 static int
 174 dissect_mrdisc_mrst(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
 175 {
 176         /* skip reserved byte */
 177         offset += 1;
 178
 179         /* checksum */
 180         igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_bad, pinfo, 0);
 181         offset += 2;
 182
 183         return offset;
 184 }
 185
 186
 187 /* This function is only called from the IGMP dissector */
 188 int
 189 dissect_mrdisc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
 190 {
 191         proto_tree *tree;
 192         proto_item *item;
 193         guint8 type;
 194
 195         if (!proto_is_protocol_enabled(find_protocol_by_id(proto_mrdisc))) {
 196                 /* we are not enabled, skip entire packet to be nice
 197                    to the igmp layer. (so clicking on IGMP will display the data)
 198                  */
 199                 return offset+tvb_length_remaining(tvb, offset);
 200         }
 201
 202         item = proto_tree_add_item(parent_tree, proto_mrdisc, tvb, offset, 0, FALSE);
 203         tree = proto_item_add_subtree(item, ett_mrdisc);
 204
 205
 206         if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 207                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "MRDISC");
 208         }
 209         if (check_col(pinfo->cinfo, COL_INFO)) {
 210                 col_clear(pinfo->cinfo, COL_INFO);
 211         }
 212
 213
 214         type = tvb_get_guint8(tvb, offset);
 215         if (check_col(pinfo->cinfo, COL_INFO)) {
 216                 col_add_fstr(pinfo->cinfo, COL_INFO,
 217                         "%s",val_to_str(type, mrdisc_types,
 218                                 "Unknown Type:0x%02x"));
 219         }
 220
 221         /* type of command */
 222         proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);
 223         offset += 1;
 224
 225         switch (type) {
 226         case MRDISC_MRA:
 227                 offset = dissect_mrdisc_mra(tvb, pinfo, tree, offset);
 228                 break;
 229         case MRDISC_MRS:
 230         case MRDISC_MRT:
 231                 /* MRS and MRT packets looks the same */
 232                 offset = dissect_mrdisc_mrst(tvb, pinfo, tree, offset);
 233                 break;
 234         }
 235         return offset;
 236 }
 237
 238
 239 void
 240 proto_register_mrdisc(void)
 241 {
 242         static hf_register_info hf[] = {
 243                 { &hf_type,
 244                         { "Type", "mrdisc.type", FT_UINT8, BASE_HEX,
 245                           VALS(mrdisc_types), 0, "MRDISC Packet Type", HFILL }},
 246
 247                 { &hf_checksum,
 248                         { "Checksum", "mrdisc.checksum", FT_UINT16, BASE_HEX,
 249                           NULL, 0, "MRDISC Checksum", HFILL }},
 250
 251                 { &hf_checksum_bad,
 252                         { "Bad Checksum", "mrdisc.checksum_bad", FT_BOOLEAN, BASE_NONE,
 253                           NULL, 0, "Bad MRDISC Checksum", HFILL }},
 254
 255                 { &hf_advint,
 256                         { "Advertising Interval", "mrdisc.adv_int", FT_UINT8, BASE_DEC,
 257                           NULL, 0, "MRDISC Advertising Interval in seconds", HFILL }},
 258
 259                 { &hf_numopts,
 260                         { "Number Of Options", "mrdisc.num_opts", FT_UINT16, BASE_DEC,
 261                           NULL, 0, "MRDISC Number Of Options", HFILL }},
 262
 263                 { &hf_options,
 264                         { "Options", "mrdisc.options", FT_NONE, BASE_NONE,
 265                           NULL, 0, "MRDISC Options", HFILL }},
 266
 267                 { &hf_option,
 268                         { "Option", "mrdisc.option", FT_UINT8, BASE_DEC,
 269                           VALS(mrdisc_options), 0, "MRDISC Option Type", HFILL }},
 270
 271                 { &hf_option_len,
 272                         { "Length", "mrdisc.opt_len", FT_UINT8, BASE_DEC,
 273                           NULL, 0, "MRDISC Option Length", HFILL }},
 274
 275                 { &hf_qi,
 276                         { "Query Interval", "mrdisc.query_int", FT_UINT16, BASE_DEC,
 277                           NULL, 0, "MRDISC Query Interval", HFILL }},
 278
 279                 { &hf_rv,
 280                         { "Robustness Variable", "mrdisc.rob_var", FT_UINT16, BASE_DEC,
 281                           NULL, 0, "MRDISC Robustness Variable", HFILL }},
 282
 283                 { &hf_option_bytes,
 284                         { "Data", "mrdisc.option_data", FT_BYTES, BASE_NONE,
 285                           NULL, 0, "MRDISC Unknown Option Data", HFILL }},
 286
 287         };
 288         static gint *ett[] = {
 289                 &ett_mrdisc,
 290                 &ett_options,
 291         };
 292
 293         proto_mrdisc = proto_register_protocol("Multicast Router DISCovery protocol",
 294             "MRDISC", "mrdisc");
 295         proto_register_field_array(proto_mrdisc, hf, array_length(hf));
 296         proto_register_subtree_array(ett, array_length(ett));
 297 }