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 <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include <glib.h>
  37
  38 #include <epan/packet.h>
  39 #include <epan/emem.h>
  40
  41 /* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
  42 enum { MSDP_SA     = 1,
  43        MSDP_SA_REQ,
  44        MSDP_SA_RSP,
  45        MSDP_KEEP_ALIVE,
  46        MSDP_NOTIFICATION,
  47
  48        /* Theses are only assigned in MSDP spec. Their use is specifed
  49         * elsewhere */
  50        MSDP_TRACE_IN_PROGRESS,
  51        MSDP_TRACE_REPLY
  52 };
  53
  54 static const value_string msdp_types[] = {
  55         { MSDP_SA,                "IPv4 Source-Active"           },
  56         { MSDP_SA_REQ,            "IPv4 Source-Active Request"   },
  57         { MSDP_SA_RSP,            "IPv4 Source-Active Response"  },
  58         { MSDP_KEEP_ALIVE,        "KeepAlive"                    },
  59         { MSDP_NOTIFICATION,      "Notification"                 },
  60
  61         { MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progress"  },
  62         { MSDP_TRACE_REPLY,       "MSDP traceroute reply"        },
  63         { 0, NULL },
  64 };
  65
  66
  67 /* Error codes */
  68 enum { MESSAGE_HEADER_ERROR = 1,
  69        SA_REQUEST_ERROR,
  70        SA_MESSAGE_SA_RESPONSE_ERROR,
  71        HOLD_TIMER_EXPIRED,
  72        FSM_ERROR,
  73        NOTIFICATION,
  74        CEASE
  75 };
  76
  77 static const value_string error_vals[] = {
  78         { MESSAGE_HEADER_ERROR,         "Message Header Error"         },
  79         { SA_REQUEST_ERROR,             "SA-Request Error"             },
  80         { SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
  81         { HOLD_TIMER_EXPIRED,           "Hold Timer Expired"           },
  82         { FSM_ERROR,                    "Finite State Machine Error"   },
  83         { NOTIFICATION,                 "Notification"                 },
  84         { CEASE,                        "Cease"                        },
  85         { 0, NULL },
  86 };
  87
  88
  89 /* Message Header Error subcodes */
  90 static const value_string hdr_error_vals[] = {
  91         { 0, "Unspecific"         },
  92         { 2, "Bad Message Length" },
  93         { 3, "Bad Message Type"   },
  94         { 0, NULL },
  95 };
  96
  97 /* SA-Request Error subcodes (the O-bit is always clear) */
  98 static const value_string sa_req_error_vals[] = {
  99         { 0, "Unspecific"    },
 100         { 1, "Invalid Group" },
 101         { 0, NULL },
 102 };
 103
 104 /* SA-Message/SA-Response Error subcodes */
 105 static const value_string sa_msg_error_vals[] = {
 106         { 0, "Unspecific"                             },
 107         { 1, "Invalid Entry Count"                    },
 108         { 2, "Invalid RP Address"                     },
 109         { 3, "Invalid Group Address"                  },
 110         { 4, "Invalid Source Address"                 },
 111         { 5, "Invalid Sprefix Length"                 },
 112         { 6, "Looping SA (Self is RP)"                },
 113         { 7, "Unknown Encapsulation"                  },
 114         { 8, "Administrative Scope Boundary Violated" },
 115         { 0, NULL },
 116 };
 117
 118 /* Finite State Machine Error subcodes (the O-bit is always clear) */
 119 static const value_string fsm_error_vals[] = {
 120         { 0, "Unspecific"                        },
 121         { 1, "Unexpected Message Type FSM Error" },
 122         { 0, NULL },
 123 };
 124
 125 /*
 126  * Hold Timer Expired subcodes (the O-bit is always clear):
 127  * Notification subcodes (the O-bit is always clear):
 128  * Cease subcodes (the O-bit is always clear):
 129  *
 130  * These have only "Unspecific" specified.
 131  */
 132 static const value_string sa_unspec_error_vals[] = {
 133         { 0, "Unspecific" },
 134         { 0, NULL },
 135 };
 136
 137
 138 /* Initialize the protocol and registered fields */
 139 static int proto_msdp = -1;
 140 static int hf_msdp_type = -1;
 141 static int hf_msdp_length = -1;
 142
 143 static int hf_msdp_sa_entry_count = -1;
 144 static int hf_msdp_sa_rp_addr = -1;
 145 static int hf_msdp_sa_reserved = -1;
 146 static int hf_msdp_sa_sprefix_len = -1;
 147 static int hf_msdp_sa_group_addr = -1;
 148 static int hf_msdp_sa_src_addr = -1;
 149
 150 static int hf_msdp_sa_req_res = -1;
 151 static int hf_msdp_sa_req_group = -1;
 152
 153 static int hf_msdp_not_o = -1;
 154 static int hf_msdp_not_error = -1;
 155 static int hf_msdp_not_error_sub = -1;
 156
 157 static int hf_msdp_not_ipv4 = -1;
 158 static int hf_msdp_not_res = -1;
 159 static int hf_msdp_not_entry_count = -1;
 160 static int hf_msdp_not_sprefix_len = -1;
 161
 162
 163 static gint ett_msdp = -1;
 164 static gint ett_msdp_sa_entry = -1;
 165 static gint ett_msdp_sa_enc_data = -1;
 166 static gint ett_msdp_not_data = -1;
 167
 168
 169 static dissector_handle_t ip_handle;
 170
 171
 172 static void
 173 dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 174     int *offset, int len);
 175 static void
 176 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 177
 178
 179 static void
 180 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 181 {
 182         proto_item *ti;
 183         proto_tree *msdp_tree;
 184         int offset;
 185
 186         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 187                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 188
 189         if (check_col(pinfo->cinfo, COL_INFO))
 190                 col_add_str(pinfo->cinfo, COL_INFO, val_to_str(tvb_get_guint8(tvb, 0),
 191                                                             msdp_types,
 192                                                             "<Unknown MSDP message type>"));
 193
 194         if (tree) {
 195                 guint8 type;
 196                 guint16 length;
 197
 198                 ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, FALSE);
 199                 msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 200
 201                 offset = 0;
 202                 while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 203                         type = tvb_get_guint8(tvb, offset);
 204                         length = tvb_get_ntohs(tvb, offset + 1);
 205                         if (length < 3)
 206                                 break;
 207                         proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 208                         proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 209                         offset += 3;
 210                         length -= 3;
 211
 212                         switch (type) {
 213                         case MSDP_SA:
 214                         case MSDP_SA_RSP:
 215                                 dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset,
 216                                     length);
 217                                 break;
 218                         case MSDP_SA_REQ:
 219                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, FALSE);
 220                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, FALSE);
 221                                 offset += 5;
 222                                 break;
 223                         case MSDP_NOTIFICATION:
 224                                 dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
 225                                 break;
 226                         default:
 227                                 if (length > 0)
 228                                         proto_tree_add_text(msdp_tree, tvb, offset, length, "TLV contents");
 229                                 offset += length;
 230                                 break;
 231                         }
 232                 }
 233
 234                 if (tvb_length_remaining(tvb, offset) > 0)
 235                         proto_tree_add_text(msdp_tree, tvb, offset,
 236                                             -1, "Trailing junk");
 237         }
 238
 239         return;
 240 }
 241
 242 /* Both Source-Active and Source-Active Response have the same format
 243  * with one exception. Encapsulated multicast data is not allowed in
 244  * SA Response.
 245  */
 246 static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo,
 247     proto_tree *tree, int *offset, int length)
 248 {
 249         guint8 entries;
 250
 251         if (length < 1)
 252                 return;
 253         entries = tvb_get_guint8(tvb, *offset);
 254         proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
 255         *offset += 1;
 256         length -= 1;
 257
 258         if (length < 4) {
 259                 *offset += length;
 260                 length = 0;
 261                 return;
 262         }
 263         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, FALSE);
 264         *offset += 4;
 265         length -= 4;
 266
 267         /* Put each of the (S,G) entries in their own subtree.
 268          * This is probably visually better.
 269          */
 270         while (entries-- > 0) {
 271                 proto_item *ei;
 272                 proto_tree *entry_tree;
 273
 274                 if (length < 12) {
 275                         *offset += length;
 276                         length = 0;
 277                         return;
 278                 }
 279                 ei = proto_tree_add_text(tree, tvb, *offset, 12, "(S,G) block: %s/%u -> %s",
 280                                          ip_to_str(tvb_get_ptr(tvb, *offset + 8, 4)),
 281                                          tvb_get_guint8(tvb, *offset + 3),
 282                                          ip_to_str(tvb_get_ptr(tvb, *offset + 4, 4)));
 283                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 284
 285                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, FALSE);
 286                 *offset += 3;
 287                 length -= 3;
 288                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, FALSE);
 289                 *offset += 1;
 290                 length -= 1;
 291                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, FALSE);
 292                 *offset += 4;
 293                 length -= 4;
 294                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, FALSE);
 295                 *offset += 4;
 296                 length -= 4;
 297         }
 298
 299         /*
 300          * Check if an encapsulated multicast IPv4 packet follows
 301          */
 302         if (length > 0) {
 303                 proto_item *ei;
 304                 proto_tree *enc_tree;
 305                 gint available_length, reported_length;
 306                 tvbuff_t *next_tvb;
 307
 308                 ei = proto_tree_add_text(tree, tvb, *offset, length,
 309                                          "Encapsulated IPv4 packet: %u bytes",
 310                                          length);
 311                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 312
 313                 available_length = tvb_length_remaining(tvb, *offset);
 314                 reported_length = tvb_reported_length_remaining(tvb, *offset);
 315                 DISSECTOR_ASSERT(available_length >= 0);
 316                 DISSECTOR_ASSERT(reported_length >= 0);
 317                 if (available_length > reported_length)
 318                         available_length = reported_length;
 319                 if (available_length > length)
 320                         available_length = length;
 321                 if (reported_length > length)
 322                         reported_length = length;
 323
 324                 next_tvb = tvb_new_subset(tvb, *offset, available_length,
 325                                           reported_length);
 326                 /* Set the information columns read-only so that they
 327                  * reflect the MSDP packet rather than the
 328                  * encapsulated packet.
 329                  */
 330                 col_set_writable(pinfo->cinfo, FALSE);
 331                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 332         }
 333         *offset += length;
 334
 335         return;
 336 }
 337
 338 /* Note: updates *offset */
 339 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 340 {
 341         guint32 ipaddr;
 342
 343         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, FALSE);
 344         *offset += 3;
 345         ipaddr = tvb_get_ipv4(tvb, *offset);
 346         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 347                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 348         *offset += 4;
 349
 350         return;
 351 }
 352
 353 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 354 {
 355         guint8 error, error_sub;
 356         const value_string *vals;
 357
 358         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, FALSE);
 359         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, FALSE);
 360         error = tvb_get_guint8(tvb, *offset);
 361         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 362         *offset += 1;
 363
 364         /* Depending on the Error Code, we collect the correct
 365          * value_strings for the Error subcode
 366          */
 367         switch (error) {
 368         case MESSAGE_HEADER_ERROR:
 369                 vals = hdr_error_vals;
 370                 break;
 371         case SA_REQUEST_ERROR:
 372                 vals = sa_req_error_vals;
 373                 break;
 374         case SA_MESSAGE_SA_RESPONSE_ERROR:
 375                 vals = sa_msg_error_vals;
 376                 break;
 377         case FSM_ERROR:
 378                 vals = fsm_error_vals;
 379                 break;
 380         case HOLD_TIMER_EXPIRED:
 381         case NOTIFICATION:
 382         case CEASE:
 383                 vals = sa_unspec_error_vals;
 384                 break;
 385         default:
 386                 vals = sa_unspec_error_vals;
 387                 break;
 388         }
 389
 390         error_sub = tvb_get_guint8(tvb, *offset);
 391         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 392                                    error_sub, "Error subcode: %s (%u)",
 393                                    val_to_str(error_sub, vals, "<Unknown Error subcode>"),
 394                                    error_sub);
 395         *offset += 1;
 396
 397         /* Do switch again, this time to dissect the data portion
 398          * correctly. Ugly.
 399          */
 400         switch (error) {
 401                 tvbuff_t *next_tvb;
 402         case SA_REQUEST_ERROR:
 403                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 404                 break;
 405         case SA_MESSAGE_SA_RESPONSE_ERROR:
 406                 if (error_sub == 0) {
 407                         break;
 408                 } else if (error_sub == 1) {
 409                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, FALSE);
 410                         *offset += 1;
 411                         break;
 412                 } else if (error_sub == 2) {
 413                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 414                         break;
 415                 } else if (error_sub == 3 || error_sub == 8) {
 416                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 417                         break;
 418                 } else if (error_sub == 4) {
 419                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 420                         break;
 421                 } else if (error_sub == 5) {
 422                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, FALSE);
 423                         *offset += 1;
 424                         break;
 425                 } else if (error_sub == 6) {
 426                         /* No break, causes fall through to next label */
 427                 } else if (error_sub == 7) {
 428                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 429                                             "Packet with unknown encapsulation: %u bytes",
 430                                             tlv_len - 5);
 431                         *offset += tlv_len - 5;
 432                         break;
 433                 } else {
 434                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 435                                             "<Unknown data>: %u bytes",
 436                                             tlv_len -5);
 437                         *offset += tlv_len - 5;
 438                         break;
 439                 }
 440                 /* Fall through */
 441         case MESSAGE_HEADER_ERROR:
 442         case NOTIFICATION:
 443                 /* Data contains the message that had an error. Even a
 444                  * broken Notification message causes a Notification
 445                  * message with Error Code set to Notification to be
 446                  * sent back.
 447                  */
 448                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 449                 dissect_msdp(next_tvb, pinfo, tree);
 450                 break;
 451         case FSM_ERROR:
 452         case HOLD_TIMER_EXPIRED:
 453         case CEASE:
 454                 /* Do nothing. These contain no data */
 455                 break;
 456         default:
 457                 if (tlv_len - 5 > 0)
 458                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 459                                     "<Unknown data>: %u bytes",
 460                                     tlv_len -5);
 461                 *offset += tlv_len - 5;
 462                 break;
 463         }
 464
 465         return;
 466 }
 467
 468 void
 469 proto_register_msdp(void)
 470 {
 471         static hf_register_info hf[] = {
 472                 { &hf_msdp_type,
 473                         { "Type",           "msdp.type",
 474                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 475                         "MSDP TLV type", HFILL }
 476                 },
 477                 { &hf_msdp_length,
 478                         { "Length",           "msdp.length",
 479                         FT_UINT16, BASE_DEC, NULL, 0,
 480                         "MSDP TLV Length", HFILL }
 481                 },
 482                 { &hf_msdp_sa_entry_count,
 483                         { "Entry Count",           "msdp.sa.entry_count",
 484                         FT_UINT8, BASE_DEC, NULL, 0,
 485                         "MSDP SA Entry Count", HFILL }
 486                 },
 487                 { &hf_msdp_sa_rp_addr,
 488                         { "RP Address",           "msdp.sa.rp_addr",
 489                         FT_IPv4, 0, NULL, 0,
 490                         "Active source's RP address", HFILL }
 491                 },
 492                 { &hf_msdp_sa_reserved,
 493                         { "Reserved",           "msdp.sa.reserved",
 494                         FT_UINT24, BASE_HEX, NULL, 0,
 495                         "Transmitted as zeros and ignored by a receiver", HFILL }
 496                 },
 497                 { &hf_msdp_sa_sprefix_len,
 498                         { "Sprefix len",           "msdp.sa.sprefix_len",
 499                         FT_UINT8, BASE_DEC, NULL, 0,
 500                         "The route prefix length associated with source address", HFILL }
 501                 },
 502                 { &hf_msdp_sa_group_addr,
 503                         { "Group Address",           "msdp.sa.group_addr",
 504                         FT_IPv4, 0, NULL, 0,
 505                         "The group address the active source has sent data to", HFILL }
 506                 },
 507                 { &hf_msdp_sa_src_addr,
 508                         { "Source Address",           "msdp.sa.src_addr",
 509                         FT_IPv4, 0, NULL, 0,
 510                         "The IP address of the active source", HFILL }
 511                 },
 512                 { &hf_msdp_sa_req_res,
 513                         { "Reserved",           "msdp.sa_req.res",
 514                         FT_UINT8, BASE_HEX, NULL, 0,
 515                         "Transmitted as zeros and ignored by a receiver", HFILL }
 516                 },
 517                 { &hf_msdp_sa_req_group,
 518                         { "Group Address",           "msdp.sa_req.group_addr",
 519                         FT_IPv4, 0, NULL, 0,
 520                         "The group address the MSDP peer is requesting", HFILL }
 521                 },
 522                 { &hf_msdp_not_o,
 523                         { "Open-bit",           "msdp.not.o",
 524                         FT_UINT8, BASE_HEX, NULL, 0x80,
 525                         "If clear, the connection will be closed", HFILL }
 526                 },
 527                 { &hf_msdp_not_error,
 528                         { "Error Code",           "msdp.not.error",
 529                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 530                         "Indicates the type of Notification", HFILL }
 531                 },
 532                 { &hf_msdp_not_error_sub,
 533                         { "Error subode",           "msdp.not.error_sub",
 534                         FT_UINT8, BASE_DEC, NULL, 0,
 535                         "Error subcode", HFILL }
 536                 },
 537                 { &hf_msdp_not_ipv4,
 538                         { "IPv4 address",           "msdp.not.ipv4",
 539                         FT_IPv4, 0, NULL, 0,
 540                         "Group/RP/Source address in Notification messages", HFILL }
 541                 },
 542                 { &hf_msdp_not_res,
 543                         { "Reserved",           "msdp.not.res",
 544                         FT_UINT24, BASE_HEX, NULL, 0,
 545                         "Reserved field in Notification messages", HFILL }
 546                 },
 547                 { &hf_msdp_not_entry_count,
 548                         { "Entry Count",           "msdp.not.entry_count",
 549                         FT_UINT24, BASE_HEX, NULL, 0,
 550                         "Entry Count in Notification messages", HFILL }
 551                 },
 552                 { &hf_msdp_not_sprefix_len,
 553                         { "Sprefix len",           "msdp.not.sprefix_len",
 554                         FT_UINT8, BASE_DEC, NULL, 0,
 555                         "Source prefix length in Notification messages", HFILL }
 556                 },
 557         };
 558
 559         static gint *ett[] = {
 560                 &ett_msdp,
 561                 &ett_msdp_sa_entry,
 562                 &ett_msdp_sa_enc_data,
 563                 &ett_msdp_not_data,
 564         };
 565
 566         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 567             "MSDP", "msdp");
 568
 569         proto_register_field_array(proto_msdp, hf, array_length(hf));
 570         proto_register_subtree_array(ett, array_length(ett));
 571 }
 572
 573 void
 574 proto_reg_handoff_msdp(void)
 575 {
 576         dissector_handle_t msdp_handle;
 577
 578         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 579         dissector_add("tcp.port", 639, msdp_handle);
 580
 581         ip_handle = find_dissector("ip");
 582
 583         return;
 584 }