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: packet-msdp.c,v 1.8 2003/01/20 06:24:37 guy Exp $
   8  *
   9  * Ethereal - Network traffic analyzer
  10  * By Gerald Combs <gerald@ethereal.com>
  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
  40 /* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
  41 enum { MSDP_SA     = 1,
  42        MSDP_SA_REQ,
  43        MSDP_SA_RSP,
  44        MSDP_KEEP_ALIVE,
  45        MSDP_NOTIFICATION,
  46
  47        /* Theses are only assigned in MSDP spec. Their use is specifed
  48         * elsewhere */
  49        MSDP_TRACE_IN_PROGRESS,
  50        MSDP_TRACE_REPLY
  51 };
  52
  53 static const value_string msdp_types[] = {
  54         { MSDP_SA,                "IPv4 Source-Active"           },
  55         { MSDP_SA_REQ,            "IPv4 Source-Active Request"   },
  56         { MSDP_SA_RSP,            "IPv4 Source-Active Response"  },
  57         { MSDP_KEEP_ALIVE,        "KeepAlive"                    },
  58         { MSDP_NOTIFICATION,      "Notification"                 },
  59
  60         { MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progresss" },
  61         { MSDP_TRACE_REPLY,       "MSDP traceroute reply"        },
  62         { 0, NULL },
  63 };
  64
  65
  66 /* Error codes */
  67 enum { MESSAGE_HEADER_ERROR = 1,
  68        SA_REQUEST_ERROR,
  69        SA_MESSAGE_SA_RESPONSE_ERROR,
  70        HOLD_TIMER_EXPIRED,
  71        FSM_ERROR,
  72        NOTIFICATION,
  73        CEASE
  74 };
  75
  76 static const value_string error_vals[] = {
  77         { MESSAGE_HEADER_ERROR,         "Message Header Error"         },
  78         { SA_REQUEST_ERROR,             "SA-Request Error"             },
  79         { SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
  80         { HOLD_TIMER_EXPIRED,           "Hold Timer Expired"           },
  81         { FSM_ERROR,                    "Finite State Machine Error"   },
  82         { NOTIFICATION,                 "Notification"                 },
  83         { CEASE,                        "Cease"                        },
  84         { 0, NULL },
  85 };
  86
  87
  88 /* Message Header Error subcodes */
  89 static const value_string hdr_error_vals[] = {
  90         { 0, "Unspecific"         },
  91         { 2, "Bad Message Length" },
  92         { 3, "Bad Message Type"   },
  93         { 0, NULL },
  94 };
  95
  96 /* SA-Request Error subcodes (the O-bit is always clear) */
  97 static const value_string sa_req_error_vals[] = {
  98         { 0, "Unspecific"    },
  99         { 1, "Invalid Group" },
 100         { 0, NULL },
 101 };
 102
 103 /* SA-Message/SA-Response Error subcodes */
 104 static const value_string sa_msg_error_vals[] = {
 105         { 0, "Unspecific"                             },
 106         { 1, "Invalid Entry Count"                    },
 107         { 2, "Invalid RP Address"                     },
 108         { 3, "Invalid Group Address"                  },
 109         { 4, "Invalid Source Address"                 },
 110         { 5, "Invalid Sprefix Length"                 },
 111         { 6, "Looping SA (Self is RP)"                },
 112         { 7, "Unknown Encapsulation"                  },
 113         { 8, "Administrative Scope Boundary Violated" },
 114         { 0, NULL },
 115 };
 116
 117 /* Finite State Machine Error subcodes (the O-bit is always clear) */
 118 static const value_string fsm_error_vals[] = {
 119         { 0, "Unspecific"                        },
 120         { 1, "Unexpected Message Type FSM Error" },
 121         { 0, NULL },
 122 };
 123
 124 /*
 125  * Hold Timer Expired subcodes (the O-bit is always clear):
 126  * Notification subcodes (the O-bit is always clear):
 127  * Cease subcodes (the O-bit is always clear):
 128  *
 129  * These have only "Unspecific" specified.
 130  */
 131 static const value_string sa_unspec_error_vals[] = {
 132         { 0, "Unspecific" },
 133         { 0, NULL },
 134 };
 135
 136
 137 /* Initialize the protocol and registered fields */
 138 static int proto_msdp = -1;
 139 static int hf_msdp_type = -1;
 140 static int hf_msdp_length = -1;
 141
 142 static int hf_msdp_sa_entry_count = -1;
 143 static int hf_msdp_sa_rp_addr = -1;
 144 static int hf_msdp_sa_reserved = -1;
 145 static int hf_msdp_sa_sprefix_len = -1;
 146 static int hf_msdp_sa_group_addr = -1;
 147 static int hf_msdp_sa_src_addr = -1;
 148
 149 static int hf_msdp_sa_req_res = -1;
 150 static int hf_msdp_sa_req_group = -1;
 151
 152 static int hf_msdp_not_o = -1;
 153 static int hf_msdp_not_error = -1;
 154 static int hf_msdp_not_error_sub = -1;
 155
 156 static int hf_msdp_not_ipv4 = -1;
 157 static int hf_msdp_not_res = -1;
 158 static int hf_msdp_not_entry_count = -1;
 159 static int hf_msdp_not_sprefix_len = -1;
 160
 161
 162 static gint ett_msdp = -1;
 163 static gint ett_msdp_sa_entry = -1;
 164 static gint ett_msdp_sa_enc_data = -1;
 165 static gint ett_msdp_not_data = -1;
 166
 167
 168 static dissector_handle_t ip_handle;
 169
 170
 171 static void
 172 dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 173     int *offset, int len);
 174 static void
 175 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 176
 177
 178 static void
 179 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 180 {
 181         proto_item *ti;
 182         proto_tree *msdp_tree;
 183         int offset;
 184
 185         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 186                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 187
 188         if (check_col(pinfo->cinfo, COL_INFO))
 189                 col_set_str(pinfo->cinfo, COL_INFO, val_to_str(tvb_get_guint8(tvb, 0),
 190                                                             msdp_types,
 191                                                             "<Unknown MSDP message type>"));
 192
 193         if (tree) {
 194                 guint8 type;
 195                 guint16 length;
 196
 197                 ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, FALSE);
 198                 msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 199
 200                 offset = 0;
 201                 while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 202                         type = tvb_get_guint8(tvb, offset);
 203                         length = tvb_get_ntohs(tvb, offset + 1);
 204                         if (length < 3)
 205                                 break;
 206                         proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 207                         proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 208                         offset += 3;
 209                         length -= 3;
 210
 211                         switch (type) {
 212                         case MSDP_SA:
 213                         case MSDP_SA_RSP:
 214                                 dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset,
 215                                     length);
 216                                 break;
 217                         case MSDP_SA_REQ:
 218                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, FALSE);
 219                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, FALSE);
 220                                 offset += 5;
 221                                 break;
 222                         case MSDP_NOTIFICATION:
 223                                 dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
 224                                 break;
 225                         default:
 226                                 if (length > 0)
 227                                         proto_tree_add_text(msdp_tree, tvb, offset, length, "TLV contents");
 228                                 offset += length;
 229                                 break;
 230                         }
 231                 }
 232
 233                 if (tvb_length_remaining(tvb, offset) > 0)
 234                         proto_tree_add_text(msdp_tree, tvb, offset,
 235                                             -1, "Trailing junk");
 236         }
 237
 238         return;
 239 }
 240
 241 /* Both Source-Active and Source-Active Response have the same format
 242  * with one exception. Encapsulated multicast data is not allowed in
 243  * SA Response.
 244  */
 245 static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo,
 246     proto_tree *tree, int *offset, int length)
 247 {
 248         guint8 entries;
 249         guint32 rp_addr;
 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         tvb_memcpy(tvb, (guint8 *)&rp_addr, *offset, 4);
 264         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, FALSE);
 265         *offset += 4;
 266         length -= 4;
 267
 268         /* Put each of the (S,G) entries in their own subtree.
 269          * This is probably visually better.
 270          */
 271         while (entries-- > 0) {
 272                 proto_item *ei;
 273                 proto_tree *entry_tree;
 274
 275                 if (length < 12) {
 276                         *offset += length;
 277                         length = 0;
 278                         return;
 279                 }
 280                 ei = proto_tree_add_text(tree, tvb, *offset, 12, "(S,G) block: %s/%u -> %s",
 281                                          ip_to_str(tvb_get_ptr(tvb, *offset + 8, 4)),
 282                                          tvb_get_guint8(tvb, *offset + 3),
 283                                          ip_to_str(tvb_get_ptr(tvb, *offset + 4, 4)));
 284                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 285
 286                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, FALSE);
 287                 *offset += 3;
 288                 length -= 3;
 289                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, FALSE);
 290                 *offset += 1;
 291                 length -= 1;
 292                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, FALSE);
 293                 *offset += 4;
 294                 length -= 4;
 295                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, FALSE);
 296                 *offset += 4;
 297                 length -= 4;
 298         }
 299
 300         /*
 301          * Check if an encapsulated multicast IPv4 packet follows
 302          */
 303         if (length > 0) {
 304                 proto_item *ei;
 305                 proto_tree *enc_tree;
 306                 gint available_length, reported_length;
 307                 tvbuff_t *next_tvb;
 308
 309                 ei = proto_tree_add_text(tree, tvb, *offset, length,
 310                                          "Encapsulated IPv4 packet: %u bytes",
 311                                          length);
 312                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 313
 314                 available_length = tvb_length_remaining(tvb, *offset);
 315                 reported_length = tvb_reported_length_remaining(tvb, *offset);
 316                 g_assert(available_length >= 0);
 317                 g_assert(reported_length >= 0);
 318                 if (available_length > reported_length)
 319                         available_length = reported_length;
 320                 if (available_length > length)
 321                         available_length = length;
 322                 if (reported_length > length)
 323                         reported_length = length;
 324
 325                 next_tvb = tvb_new_subset(tvb, *offset, available_length,
 326                                           reported_length);
 327                 /* Set the information columns read-only so that they
 328                  * reflect the MSDP packet rather than the
 329                  * encapsulated packet.
 330                  */
 331                 col_set_writable(pinfo->cinfo, FALSE);
 332                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 333         }
 334         *offset += length;
 335
 336         return;
 337 }
 338
 339 /* Note: updates *offset */
 340 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 341 {
 342         guint32 ipaddr;
 343
 344         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, FALSE);
 345         *offset += 3;
 346         tvb_memcpy(tvb, (guint8 *)&ipaddr, *offset, 4);
 347         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 348                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 349         *offset += 4;
 350
 351         return;
 352 }
 353
 354 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 355 {
 356         guint8 error, error_sub;
 357         const value_string *vals;
 358
 359         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, FALSE);
 360         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, FALSE);
 361         error = tvb_get_guint8(tvb, *offset);
 362         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 363         *offset += 1;
 364
 365         /* Depending on the Error Code, we collect the correct
 366          * value_strings for the Error subcode
 367          */
 368         switch (error) {
 369         case MESSAGE_HEADER_ERROR:
 370                 vals = hdr_error_vals;
 371                 break;
 372         case SA_REQUEST_ERROR:
 373                 vals = sa_req_error_vals;
 374                 break;
 375         case SA_MESSAGE_SA_RESPONSE_ERROR:
 376                 vals = sa_msg_error_vals;
 377                 break;
 378         case FSM_ERROR:
 379                 vals = fsm_error_vals;
 380                 break;
 381         case HOLD_TIMER_EXPIRED:
 382         case NOTIFICATION:
 383         case CEASE:
 384                 vals = sa_unspec_error_vals;
 385                 break;
 386         default:
 387                 vals = sa_unspec_error_vals;
 388                 break;
 389         }
 390
 391         error_sub = tvb_get_guint8(tvb, *offset);
 392         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 393                                    error_sub, "Error subcode: %s (%u)",
 394                                    val_to_str(error_sub, vals, "<Unknown Error subcode>"),
 395                                    error_sub);
 396         *offset += 1;
 397
 398         /* Do switch again, this time to dissect the data portion
 399          * correctly. Ugly.
 400          */
 401         switch (error) {
 402                 tvbuff_t *next_tvb;
 403         case SA_REQUEST_ERROR:
 404                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 405                 break;
 406         case SA_MESSAGE_SA_RESPONSE_ERROR:
 407                 if (error_sub == 0) {
 408                         break;
 409                 } else if (error_sub == 1) {
 410                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, FALSE);
 411                         *offset += 1;
 412                         break;
 413                 } else if (error_sub == 2) {
 414                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 415                         break;
 416                 } else if (error_sub == 3 || error_sub == 8) {
 417                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 418                         break;
 419                 } else if (error_sub == 4) {
 420                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 421                         break;
 422                 } else if (error_sub == 5) {
 423                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, FALSE);
 424                         *offset += 1;
 425                         break;
 426                 } else if (error_sub == 6) {
 427                         /* No break, causes fall through to next label */
 428                 } else if (error_sub == 7) {
 429                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 430                                             "Packet with unknown encapsulation: %u bytes",
 431                                             tlv_len - 5);
 432                         *offset += tlv_len - 5;
 433                         break;
 434                 } else {
 435                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 436                                             "<Unknown data>: %u bytes",
 437                                             tlv_len -5);
 438                         *offset += tlv_len - 5;
 439                         break;
 440                 }
 441                 /* Fall through */
 442         case MESSAGE_HEADER_ERROR:
 443         case NOTIFICATION:
 444                 /* Data contains the message that had an error. Even a
 445                  * broken Notification message causes a Notification
 446                  * message with Error Code set to Notification to be
 447                  * sent back.
 448                  */
 449                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 450                 dissect_msdp(next_tvb, pinfo, tree);
 451                 break;
 452         case FSM_ERROR:
 453         case HOLD_TIMER_EXPIRED:
 454         case CEASE:
 455                 /* Do nothing. These contain no data */
 456                 break;
 457         default:
 458                 if (tlv_len - 5 > 0)
 459                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 460                                     "<Unknown data>: %u bytes",
 461                                     tlv_len -5);
 462                 *offset += tlv_len - 5;
 463                 break;
 464         }
 465
 466         return;
 467 }
 468
 469 void
 470 proto_register_msdp(void)
 471 {
 472         static hf_register_info hf[] = {
 473                 { &hf_msdp_type,
 474                         { "Type",           "msdp.type",
 475                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 476                         "MSDP TLV type", HFILL }
 477                 },
 478                 { &hf_msdp_length,
 479                         { "Length",           "msdp.length",
 480                         FT_UINT16, BASE_DEC, NULL, 0,
 481                         "MSDP TLV Length", HFILL }
 482                 },
 483                 { &hf_msdp_sa_entry_count,
 484                         { "Entry Count",           "msdp.sa.entry_count",
 485                         FT_UINT8, BASE_DEC, NULL, 0,
 486                         "MSDP SA Entry Count", HFILL }
 487                 },
 488                 { &hf_msdp_sa_rp_addr,
 489                         { "RP Address",           "msdp.sa.rp_addr",
 490                         FT_IPv4, 0, NULL, 0,
 491                         "Active source's RP address", HFILL }
 492                 },
 493                 { &hf_msdp_sa_reserved,
 494                         { "Reserved",           "msdp.sa.reserved",
 495                         FT_UINT24, BASE_HEX, NULL, 0,
 496                         "Transmitted as zeros and ignored by a receiver", HFILL }
 497                 },
 498                 { &hf_msdp_sa_sprefix_len,
 499                         { "Sprefix len",           "msdp.sa.sprefix_len",
 500                         FT_UINT8, BASE_DEC, NULL, 0,
 501                         "The route prefix length associated with source address", HFILL }
 502                 },
 503                 { &hf_msdp_sa_group_addr,
 504                         { "Group Address",           "msdp.sa.group_addr",
 505                         FT_IPv4, 0, NULL, 0,
 506                         "The group address the active source has sent data to", HFILL }
 507                 },
 508                 { &hf_msdp_sa_src_addr,
 509                         { "Source Address",           "msdp.sa.src_addr",
 510                         FT_IPv4, 0, NULL, 0,
 511                         "The IP address of the active source", HFILL }
 512                 },
 513                 { &hf_msdp_sa_req_res,
 514                         { "Reserved",           "msdp.sa_req.res",
 515                         FT_UINT8, BASE_HEX, NULL, 0,
 516                         "Transmitted as zeros and ignored by a receiver", HFILL }
 517                 },
 518                 { &hf_msdp_sa_req_group,
 519                         { "Group Address",           "msdp.sa_req.group_addr",
 520                         FT_IPv4, 0, NULL, 0,
 521                         "The group address the MSDP peer is requesting", HFILL }
 522                 },
 523                 { &hf_msdp_not_o,
 524                         { "Open-bit",           "msdp.not.o",
 525                         FT_UINT8, BASE_HEX, NULL, 0x80,
 526                         "If clear, the connection will be closed", HFILL }
 527                 },
 528                 { &hf_msdp_not_error,
 529                         { "Error Code",           "msdp.not.error",
 530                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 531                         "Indicates the type of Notification", HFILL }
 532                 },
 533                 { &hf_msdp_not_error_sub,
 534                         { "Error subode",           "msdp.not.error_sub",
 535                         FT_UINT8, BASE_DEC, NULL, 0,
 536                         "Error subcode", HFILL }
 537                 },
 538                 { &hf_msdp_not_ipv4,
 539                         { "IPv4 address",           "msdp.not.ipv4",
 540                         FT_IPv4, 0, NULL, 0,
 541                         "Group/RP/Source address in Notification messages", HFILL }
 542                 },
 543                 { &hf_msdp_not_res,
 544                         { "Reserved",           "msdp.not.res",
 545                         FT_UINT24, BASE_HEX, NULL, 0,
 546                         "Reserved field in Notification messages", HFILL }
 547                 },
 548                 { &hf_msdp_not_entry_count,
 549                         { "Entry Count",           "msdp.not.entry_count",
 550                         FT_UINT24, BASE_HEX, NULL, 0,
 551                         "Entry Count in Notification messages", HFILL }
 552                 },
 553                 { &hf_msdp_not_sprefix_len,
 554                         { "Sprefix len",           "msdp.not.sprefix_len",
 555                         FT_UINT8, BASE_DEC, NULL, 0,
 556                         "Source prefix length in Notification messages", HFILL }
 557                 },
 558         };
 559
 560         static gint *ett[] = {
 561                 &ett_msdp,
 562                 &ett_msdp_sa_entry,
 563                 &ett_msdp_sa_enc_data,
 564                 &ett_msdp_not_data,
 565         };
 566
 567         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 568             "MSDP", "msdp");
 569
 570         proto_register_field_array(proto_msdp, hf, array_length(hf));
 571         proto_register_subtree_array(ett, array_length(ett));
 572 }
 573
 574 void
 575 proto_reg_handoff_msdp(void)
 576 {
 577         dissector_handle_t msdp_handle;
 578
 579         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 580         dissector_add("tcp.port", 639, msdp_handle);
 581
 582         ip_handle = find_dissector("ip");
 583
 584         return;
 585 }