epan/dissectors/packet-msdp.c

   1 /* packet-msdp.c
   2  * Routines for Multicast Source Discovery Protocol (MSDP) dissection.
   3  * draft-ietf-msdp-spec-10.txt
   4  *
   5  * Copyright 2001, Heikki Vatiainen <hessu@cs.tut.fi>
   6  *
   7  * $Id$
   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  26  */
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <stdlib.h>
  33
  34 #include <glib.h>
  35
  36 #include <epan/packet.h>
  37
  38 /* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
  39 enum { MSDP_SA     = 1,
  40        MSDP_SA_REQ,
  41        MSDP_SA_RSP,
  42        MSDP_KEEP_ALIVE,
  43        MSDP_NOTIFICATION,
  44
  45        /* Theses are only assigned in MSDP spec. Their use is specifed
  46         * elsewhere */
  47        MSDP_TRACE_IN_PROGRESS,
  48        MSDP_TRACE_REPLY
  49 };
  50
  51 static const value_string msdp_types[] = {
  52         { MSDP_SA,                "IPv4 Source-Active"           },
  53         { MSDP_SA_REQ,            "IPv4 Source-Active Request"   },
  54         { MSDP_SA_RSP,            "IPv4 Source-Active Response"  },
  55         { MSDP_KEEP_ALIVE,        "KeepAlive"                    },
  56         { MSDP_NOTIFICATION,      "Notification"                 },
  57
  58         { MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progress"  },
  59         { MSDP_TRACE_REPLY,       "MSDP traceroute reply"        },
  60         { 0, NULL },
  61 };
  62
  63
  64 /* Error codes */
  65 enum { MESSAGE_HEADER_ERROR = 1,
  66        SA_REQUEST_ERROR,
  67        SA_MESSAGE_SA_RESPONSE_ERROR,
  68        HOLD_TIMER_EXPIRED,
  69        FSM_ERROR,
  70        NOTIFICATION,
  71        CEASE
  72 };
  73
  74 static const value_string error_vals[] = {
  75         { MESSAGE_HEADER_ERROR,         "Message Header Error"         },
  76         { SA_REQUEST_ERROR,             "SA-Request Error"             },
  77         { SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
  78         { HOLD_TIMER_EXPIRED,           "Hold Timer Expired"           },
  79         { FSM_ERROR,                    "Finite State Machine Error"   },
  80         { NOTIFICATION,                 "Notification"                 },
  81         { CEASE,                        "Cease"                        },
  82         { 0, NULL },
  83 };
  84
  85
  86 /* Message Header Error subcodes */
  87 static const value_string hdr_error_vals[] = {
  88         { 0, "Unspecific"         },
  89         { 2, "Bad Message Length" },
  90         { 3, "Bad Message Type"   },
  91         { 0, NULL },
  92 };
  93
  94 /* SA-Request Error subcodes (the O-bit is always clear) */
  95 static const value_string sa_req_error_vals[] = {
  96         { 0, "Unspecific"    },
  97         { 1, "Invalid Group" },
  98         { 0, NULL },
  99 };
 100
 101 /* SA-Message/SA-Response Error subcodes */
 102 static const value_string sa_msg_error_vals[] = {
 103         { 0, "Unspecific"                             },
 104         { 1, "Invalid Entry Count"                    },
 105         { 2, "Invalid RP Address"                     },
 106         { 3, "Invalid Group Address"                  },
 107         { 4, "Invalid Source Address"                 },
 108         { 5, "Invalid Sprefix Length"                 },
 109         { 6, "Looping SA (Self is RP)"                },
 110         { 7, "Unknown Encapsulation"                  },
 111         { 8, "Administrative Scope Boundary Violated" },
 112         { 0, NULL },
 113 };
 114
 115 /* Finite State Machine Error subcodes (the O-bit is always clear) */
 116 static const value_string fsm_error_vals[] = {
 117         { 0, "Unspecific"                        },
 118         { 1, "Unexpected Message Type FSM Error" },
 119         { 0, NULL },
 120 };
 121
 122 /*
 123  * Hold Timer Expired subcodes (the O-bit is always clear):
 124  * Notification subcodes (the O-bit is always clear):
 125  * Cease subcodes (the O-bit is always clear):
 126  *
 127  * These have only "Unspecific" specified.
 128  */
 129 static const value_string sa_unspec_error_vals[] = {
 130         { 0, "Unspecific" },
 131         { 0, NULL },
 132 };
 133
 134
 135 /* Initialize the protocol and registered fields */
 136 static int proto_msdp = -1;
 137 static int hf_msdp_type = -1;
 138 static int hf_msdp_length = -1;
 139
 140 static int hf_msdp_sa_entry_count = -1;
 141 static int hf_msdp_sa_rp_addr = -1;
 142 static int hf_msdp_sa_reserved = -1;
 143 static int hf_msdp_sa_sprefix_len = -1;
 144 static int hf_msdp_sa_group_addr = -1;
 145 static int hf_msdp_sa_src_addr = -1;
 146
 147 static int hf_msdp_sa_req_res = -1;
 148 static int hf_msdp_sa_req_group = -1;
 149
 150 static int hf_msdp_not_o = -1;
 151 static int hf_msdp_not_error = -1;
 152 static int hf_msdp_not_error_sub = -1;
 153
 154 static int hf_msdp_not_ipv4 = -1;
 155 static int hf_msdp_not_res = -1;
 156 static int hf_msdp_not_entry_count = -1;
 157 static int hf_msdp_not_sprefix_len = -1;
 158
 159
 160 static gint ett_msdp = -1;
 161 static gint ett_msdp_sa_entry = -1;
 162 static gint ett_msdp_sa_enc_data = -1;
 163 static gint ett_msdp_not_data = -1;
 164
 165
 166 static dissector_handle_t ip_handle;
 167
 168
 169 static void
 170 dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 171     int *offset, int len);
 172 static void
 173 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 174
 175
 176 static void
 177 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 178 {
 179         proto_item *ti;
 180         proto_tree *msdp_tree;
 181         int offset;
 182
 183         col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 184
 185         if (check_col(pinfo->cinfo, COL_INFO))
 186                 col_add_str(pinfo->cinfo, COL_INFO, val_to_str(tvb_get_guint8(tvb, 0),
 187                                                             msdp_types,
 188                                                             "<Unknown MSDP message type>"));
 189
 190         if (tree) {
 191                 guint8 type;
 192                 guint16 length;
 193
 194                 ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, FALSE);
 195                 msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 196
 197                 offset = 0;
 198                 while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 199                         type = tvb_get_guint8(tvb, offset);
 200                         length = tvb_get_ntohs(tvb, offset + 1);
 201                         if (length < 3)
 202                                 break;
 203                         proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 204                         proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 205                         offset += 3;
 206                         length -= 3;
 207
 208                         switch (type) {
 209                         case MSDP_SA:
 210                         case MSDP_SA_RSP:
 211                                 dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset,
 212                                     length);
 213                                 break;
 214                         case MSDP_SA_REQ:
 215                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, FALSE);
 216                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, FALSE);
 217                                 offset += 5;
 218                                 break;
 219                         case MSDP_NOTIFICATION:
 220                                 dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
 221                                 break;
 222                         default:
 223                                 if (length > 0)
 224                                         proto_tree_add_text(msdp_tree, tvb, offset, length, "TLV contents");
 225                                 offset += length;
 226                                 break;
 227                         }
 228                 }
 229
 230                 if (tvb_length_remaining(tvb, offset) > 0)
 231                         proto_tree_add_text(msdp_tree, tvb, offset,
 232                                             -1, "Trailing junk");
 233         }
 234
 235         return;
 236 }
 237
 238 /* Both Source-Active and Source-Active Response have the same format
 239  * with one exception. Encapsulated multicast data is not allowed in
 240  * SA Response.
 241  */
 242 static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo,
 243     proto_tree *tree, int *offset, int length)
 244 {
 245         guint8 entries;
 246
 247         if (length < 1)
 248                 return;
 249         entries = tvb_get_guint8(tvb, *offset);
 250         proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
 251         *offset += 1;
 252         length -= 1;
 253
 254         if (length < 4) {
 255                 *offset += length;
 256                 return;
 257         }
 258         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, FALSE);
 259         *offset += 4;
 260         length -= 4;
 261
 262         /* Put each of the (S,G) entries in their own subtree.
 263          * This is probably visually better.
 264          */
 265         while (entries-- > 0) {
 266                 proto_item *ei;
 267                 proto_tree *entry_tree;
 268
 269                 if (length < 12) {
 270                         *offset += length;
 271                         return;
 272                 }
 273                 ei = proto_tree_add_text(tree, tvb, *offset, 12, "(S,G) block: %s/%u -> %s",
 274                                          ip_to_str(tvb_get_ptr(tvb, *offset + 8, 4)),
 275                                          tvb_get_guint8(tvb, *offset + 3),
 276                                          ip_to_str(tvb_get_ptr(tvb, *offset + 4, 4)));
 277                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 278
 279                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, FALSE);
 280                 *offset += 3;
 281                 length -= 3;
 282                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, FALSE);
 283                 *offset += 1;
 284                 length -= 1;
 285                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, FALSE);
 286                 *offset += 4;
 287                 length -= 4;
 288                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, FALSE);
 289                 *offset += 4;
 290                 length -= 4;
 291         }
 292
 293         /*
 294          * Check if an encapsulated multicast IPv4 packet follows
 295          */
 296         if (length > 0) {
 297                 proto_item *ei;
 298                 proto_tree *enc_tree;
 299                 gint available_length, reported_length;
 300                 tvbuff_t *next_tvb;
 301
 302                 ei = proto_tree_add_text(tree, tvb, *offset, length,
 303                                          "Encapsulated IPv4 packet: %u bytes",
 304                                          length);
 305                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 306
 307                 available_length = tvb_length_remaining(tvb, *offset);
 308                 reported_length = tvb_reported_length_remaining(tvb, *offset);
 309                 DISSECTOR_ASSERT(available_length >= 0);
 310                 DISSECTOR_ASSERT(reported_length >= 0);
 311                 if (available_length > reported_length)
 312                         available_length = reported_length;
 313                 if (available_length > length)
 314                         available_length = length;
 315                 if (reported_length > length)
 316                         reported_length = length;
 317
 318                 next_tvb = tvb_new_subset(tvb, *offset, available_length,
 319                                           reported_length);
 320                 /* Set the information columns read-only so that they
 321                  * reflect the MSDP packet rather than the
 322                  * encapsulated packet.
 323                  */
 324                 col_set_writable(pinfo->cinfo, FALSE);
 325                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 326         }
 327         *offset += length;
 328
 329         return;
 330 }
 331
 332 /* Note: updates *offset */
 333 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 334 {
 335         guint32 ipaddr;
 336
 337         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, FALSE);
 338         *offset += 3;
 339         ipaddr = tvb_get_ipv4(tvb, *offset);
 340         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 341                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 342         *offset += 4;
 343
 344         return;
 345 }
 346
 347 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 348 {
 349         guint8 error, error_sub;
 350         const value_string *vals;
 351
 352         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, FALSE);
 353         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, FALSE);
 354         error = tvb_get_guint8(tvb, *offset);
 355         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 356         *offset += 1;
 357
 358         /* Depending on the Error Code, we collect the correct
 359          * value_strings for the Error subcode
 360          */
 361         switch (error) {
 362         case MESSAGE_HEADER_ERROR:
 363                 vals = hdr_error_vals;
 364                 break;
 365         case SA_REQUEST_ERROR:
 366                 vals = sa_req_error_vals;
 367                 break;
 368         case SA_MESSAGE_SA_RESPONSE_ERROR:
 369                 vals = sa_msg_error_vals;
 370                 break;
 371         case FSM_ERROR:
 372                 vals = fsm_error_vals;
 373                 break;
 374         case HOLD_TIMER_EXPIRED:
 375         case NOTIFICATION:
 376         case CEASE:
 377                 vals = sa_unspec_error_vals;
 378                 break;
 379         default:
 380                 vals = sa_unspec_error_vals;
 381                 break;
 382         }
 383
 384         error_sub = tvb_get_guint8(tvb, *offset);
 385         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 386                                    error_sub, "Error subcode: %s (%u)",
 387                                    val_to_str(error_sub, vals, "<Unknown Error subcode>"),
 388                                    error_sub);
 389         *offset += 1;
 390
 391         /* Do switch again, this time to dissect the data portion
 392          * correctly. Ugly.
 393          */
 394         switch (error) {
 395                 tvbuff_t *next_tvb;
 396         case SA_REQUEST_ERROR:
 397                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 398                 break;
 399         case SA_MESSAGE_SA_RESPONSE_ERROR:
 400                 if (error_sub == 0) {
 401                         break;
 402                 } else if (error_sub == 1) {
 403                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, FALSE);
 404                         *offset += 1;
 405                         break;
 406                 } else if (error_sub == 2) {
 407                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 408                         break;
 409                 } else if (error_sub == 3 || error_sub == 8) {
 410                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 411                         break;
 412                 } else if (error_sub == 4) {
 413                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 414                         break;
 415                 } else if (error_sub == 5) {
 416                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, FALSE);
 417                         *offset += 1;
 418                         break;
 419                 } else if (error_sub == 6) {
 420                         /* No break, causes fall through to next label */
 421                 } else if (error_sub == 7) {
 422                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 423                                             "Packet with unknown encapsulation: %u bytes",
 424                                             tlv_len - 5);
 425                         *offset += tlv_len - 5;
 426                         break;
 427                 } else {
 428                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 429                                             "<Unknown data>: %u bytes",
 430                                             tlv_len -5);
 431                         *offset += tlv_len - 5;
 432                         break;
 433                 }
 434                 /* Fall through */
 435         case MESSAGE_HEADER_ERROR:
 436         case NOTIFICATION:
 437                 /* Data contains the message that had an error. Even a
 438                  * broken Notification message causes a Notification
 439                  * message with Error Code set to Notification to be
 440                  * sent back.
 441                  */
 442                 next_tvb = tvb_new_subset_remaining(tvb, *offset);
 443                 dissect_msdp(next_tvb, pinfo, tree);
 444                 break;
 445         case FSM_ERROR:
 446         case HOLD_TIMER_EXPIRED:
 447         case CEASE:
 448                 /* Do nothing. These contain no data */
 449                 break;
 450         default:
 451                 if (tlv_len - 5 > 0)
 452                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 453                                     "<Unknown data>: %u bytes",
 454                                     tlv_len -5);
 455                 *offset += tlv_len - 5;
 456                 break;
 457         }
 458
 459         return;
 460 }
 461
 462 void
 463 proto_register_msdp(void)
 464 {
 465         static hf_register_info hf[] = {
 466                 { &hf_msdp_type,
 467                         { "Type",           "msdp.type",
 468                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 469                         "MSDP TLV type", HFILL }
 470                 },
 471                 { &hf_msdp_length,
 472                         { "Length",           "msdp.length",
 473                         FT_UINT16, BASE_DEC, NULL, 0,
 474                         "MSDP TLV Length", HFILL }
 475                 },
 476                 { &hf_msdp_sa_entry_count,
 477                         { "Entry Count",           "msdp.sa.entry_count",
 478                         FT_UINT8, BASE_DEC, NULL, 0,
 479                         "MSDP SA Entry Count", HFILL }
 480                 },
 481                 { &hf_msdp_sa_rp_addr,
 482                         { "RP Address",           "msdp.sa.rp_addr",
 483                         FT_IPv4, BASE_NONE, NULL, 0,
 484                         "Active source's RP address", HFILL }
 485                 },
 486                 { &hf_msdp_sa_reserved,
 487                         { "Reserved",           "msdp.sa.reserved",
 488                         FT_UINT24, BASE_HEX, NULL, 0,
 489                         "Transmitted as zeros and ignored by a receiver", HFILL }
 490                 },
 491                 { &hf_msdp_sa_sprefix_len,
 492                         { "Sprefix len",           "msdp.sa.sprefix_len",
 493                         FT_UINT8, BASE_DEC, NULL, 0,
 494                         "The route prefix length associated with source address", HFILL }
 495                 },
 496                 { &hf_msdp_sa_group_addr,
 497                         { "Group Address",           "msdp.sa.group_addr",
 498                         FT_IPv4, BASE_NONE, NULL, 0,
 499                         "The group address the active source has sent data to", HFILL }
 500                 },
 501                 { &hf_msdp_sa_src_addr,
 502                         { "Source Address",           "msdp.sa.src_addr",
 503                         FT_IPv4, BASE_NONE, NULL, 0,
 504                         "The IP address of the active source", HFILL }
 505                 },
 506                 { &hf_msdp_sa_req_res,
 507                         { "Reserved",           "msdp.sa_req.res",
 508                         FT_UINT8, BASE_HEX, NULL, 0,
 509                         "Transmitted as zeros and ignored by a receiver", HFILL }
 510                 },
 511                 { &hf_msdp_sa_req_group,
 512                         { "Group Address",           "msdp.sa_req.group_addr",
 513                         FT_IPv4, BASE_NONE, NULL, 0,
 514                         "The group address the MSDP peer is requesting", HFILL }
 515                 },
 516                 { &hf_msdp_not_o,
 517                         { "Open-bit",           "msdp.not.o",
 518                         FT_UINT8, BASE_HEX, NULL, 0x80,
 519                         "If clear, the connection will be closed", HFILL }
 520                 },
 521                 { &hf_msdp_not_error,
 522                         { "Error Code",           "msdp.not.error",
 523                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 524                         "Indicates the type of Notification", HFILL }
 525                 },
 526                 { &hf_msdp_not_error_sub,
 527                         { "Error subode",           "msdp.not.error_sub",
 528                         FT_UINT8, BASE_DEC, NULL, 0,
 529                         "Error subcode", HFILL }
 530                 },
 531                 { &hf_msdp_not_ipv4,
 532                         { "IPv4 address",           "msdp.not.ipv4",
 533                         FT_IPv4, BASE_NONE, NULL, 0,
 534                         "Group/RP/Source address in Notification messages", HFILL }
 535                 },
 536                 { &hf_msdp_not_res,
 537                         { "Reserved",           "msdp.not.res",
 538                         FT_UINT24, BASE_HEX, NULL, 0,
 539                         "Reserved field in Notification messages", HFILL }
 540                 },
 541                 { &hf_msdp_not_entry_count,
 542                         { "Entry Count",           "msdp.not.entry_count",
 543                         FT_UINT24, BASE_HEX, NULL, 0,
 544                         "Entry Count in Notification messages", HFILL }
 545                 },
 546                 { &hf_msdp_not_sprefix_len,
 547                         { "Sprefix len",           "msdp.not.sprefix_len",
 548                         FT_UINT8, BASE_DEC, NULL, 0,
 549                         "Source prefix length in Notification messages", HFILL }
 550                 },
 551         };
 552
 553         static gint *ett[] = {
 554                 &ett_msdp,
 555                 &ett_msdp_sa_entry,
 556                 &ett_msdp_sa_enc_data,
 557                 &ett_msdp_not_data,
 558         };
 559
 560         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 561             "MSDP", "msdp");
 562
 563         proto_register_field_array(proto_msdp, hf, array_length(hf));
 564         proto_register_subtree_array(ett, array_length(ett));
 565 }
 566
 567 void
 568 proto_reg_handoff_msdp(void)
 569 {
 570         dissector_handle_t msdp_handle;
 571
 572         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 573         dissector_add_uint("tcp.port", 639, msdp_handle);
 574
 575         ip_handle = find_dissector("ip");
 576
 577         return;
 578 }