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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  26  */
  27
  28 #include "config.h"
  29
  30 #include <glib.h>
  31
  32 #include <epan/packet.h>
  33
  34 /* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
  35 enum { MSDP_SA     = 1,
  36        MSDP_SA_REQ,
  37        MSDP_SA_RSP,
  38        MSDP_KEEP_ALIVE,
  39        MSDP_NOTIFICATION,
  40
  41        /* Theses are only assigned in MSDP spec. Their use is specifed
  42         * elsewhere */
  43        MSDP_TRACE_IN_PROGRESS,
  44        MSDP_TRACE_REPLY
  45 };
  46
  47 static const value_string msdp_types[] = {
  48         { MSDP_SA,                "IPv4 Source-Active"           },
  49         { MSDP_SA_REQ,            "IPv4 Source-Active Request"   },
  50         { MSDP_SA_RSP,            "IPv4 Source-Active Response"  },
  51         { MSDP_KEEP_ALIVE,        "KeepAlive"                    },
  52         { MSDP_NOTIFICATION,      "Notification"                 },
  53
  54         { MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progress"  },
  55         { MSDP_TRACE_REPLY,       "MSDP traceroute reply"        },
  56         { 0, NULL },
  57 };
  58
  59
  60 /* Error codes */
  61 enum { MESSAGE_HEADER_ERROR = 1,
  62        SA_REQUEST_ERROR,
  63        SA_MESSAGE_SA_RESPONSE_ERROR,
  64        HOLD_TIMER_EXPIRED,
  65        FSM_ERROR,
  66        NOTIFICATION,
  67        CEASE
  68 };
  69
  70 static const value_string error_vals[] = {
  71         { MESSAGE_HEADER_ERROR,         "Message Header Error"         },
  72         { SA_REQUEST_ERROR,             "SA-Request Error"             },
  73         { SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
  74         { HOLD_TIMER_EXPIRED,           "Hold Timer Expired"           },
  75         { FSM_ERROR,                    "Finite State Machine Error"   },
  76         { NOTIFICATION,                 "Notification"                 },
  77         { CEASE,                        "Cease"                        },
  78         { 0, NULL },
  79 };
  80
  81
  82 /* Message Header Error subcodes */
  83 static const value_string hdr_error_vals[] = {
  84         { 0, "Unspecific"         },
  85         { 2, "Bad Message Length" },
  86         { 3, "Bad Message Type"   },
  87         { 0, NULL },
  88 };
  89
  90 /* SA-Request Error subcodes (the O-bit is always clear) */
  91 static const value_string sa_req_error_vals[] = {
  92         { 0, "Unspecific"    },
  93         { 1, "Invalid Group" },
  94         { 0, NULL },
  95 };
  96
  97 /* SA-Message/SA-Response Error subcodes */
  98 static const value_string sa_msg_error_vals[] = {
  99         { 0, "Unspecific"                             },
 100         { 1, "Invalid Entry Count"                    },
 101         { 2, "Invalid RP Address"                     },
 102         { 3, "Invalid Group Address"                  },
 103         { 4, "Invalid Source Address"                 },
 104         { 5, "Invalid Sprefix Length"                 },
 105         { 6, "Looping SA (Self is RP)"                },
 106         { 7, "Unknown Encapsulation"                  },
 107         { 8, "Administrative Scope Boundary Violated" },
 108         { 0, NULL },
 109 };
 110
 111 /* Finite State Machine Error subcodes (the O-bit is always clear) */
 112 static const value_string fsm_error_vals[] = {
 113         { 0, "Unspecific"                        },
 114         { 1, "Unexpected Message Type FSM Error" },
 115         { 0, NULL },
 116 };
 117
 118 /*
 119  * Hold Timer Expired subcodes (the O-bit is always clear):
 120  * Notification subcodes (the O-bit is always clear):
 121  * Cease subcodes (the O-bit is always clear):
 122  *
 123  * These have only "Unspecific" specified.
 124  */
 125 static const value_string sa_unspec_error_vals[] = {
 126         { 0, "Unspecific" },
 127         { 0, NULL },
 128 };
 129
 130
 131 /* Initialize the protocol and registered fields */
 132 static int proto_msdp = -1;
 133 static int hf_msdp_type = -1;
 134 static int hf_msdp_length = -1;
 135
 136 static int hf_msdp_sa_entry_count = -1;
 137 static int hf_msdp_sa_rp_addr = -1;
 138 static int hf_msdp_sa_reserved = -1;
 139 static int hf_msdp_sa_sprefix_len = -1;
 140 static int hf_msdp_sa_group_addr = -1;
 141 static int hf_msdp_sa_src_addr = -1;
 142
 143 static int hf_msdp_sa_req_res = -1;
 144 static int hf_msdp_sa_req_group = -1;
 145
 146 static int hf_msdp_not_o = -1;
 147 static int hf_msdp_not_error = -1;
 148 static int hf_msdp_not_error_sub = -1;
 149
 150 static int hf_msdp_not_ipv4 = -1;
 151 static int hf_msdp_not_res = -1;
 152 static int hf_msdp_not_entry_count = -1;
 153 static int hf_msdp_not_sprefix_len = -1;
 154
 155
 156 static gint ett_msdp = -1;
 157 static gint ett_msdp_sa_entry = -1;
 158 static gint ett_msdp_sa_enc_data = -1;
 159 static gint ett_msdp_not_data = -1;
 160
 161
 162 static dissector_handle_t ip_handle;
 163
 164
 165 static void
 166 dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 167     int *offset, int len);
 168 static void
 169 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 170
 171
 172 static void
 173 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 174 {
 175         proto_item *ti;
 176         proto_tree *msdp_tree;
 177         int         offset;
 178         guint8      type;
 179         guint16     length;
 180
 181
 182         col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 183
 184         if (check_col(pinfo->cinfo, COL_INFO))
 185                 col_add_str(pinfo->cinfo, COL_INFO, val_to_str_const(tvb_get_guint8(tvb, 0),
 186                                                                      msdp_types,
 187                                                                      "<Unknown MSDP message type>"));
 188
 189         ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, ENC_NA);
 190         msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 191
 192         offset = 0;
 193         while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 194                 type = tvb_get_guint8(tvb, offset);
 195                 length = tvb_get_ntohs(tvb, offset + 1);
 196                 if (length < 3)
 197                         break;
 198                 proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 199                 proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 200                 offset += 3;
 201                 length -= 3;
 202
 203                 switch (type) {
 204                 case MSDP_SA:
 205                 case MSDP_SA_RSP:
 206                         dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset,
 207                                         length);
 208                         break;
 209                 case MSDP_SA_REQ:
 210                         proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, ENC_BIG_ENDIAN);
 211                         proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, ENC_BIG_ENDIAN);
 212                         offset += 5;
 213                         break;
 214                 case MSDP_NOTIFICATION:
 215                         dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
 216                         break;
 217                 default:
 218                         if (length > 0)
 219                                 proto_tree_add_text(msdp_tree, tvb, offset, length, "TLV contents");
 220                         offset += length;
 221                         break;
 222                 }
 223         }
 224
 225         if (tvb_length_remaining(tvb, offset) > 0)
 226                 proto_tree_add_text(msdp_tree, tvb, offset,
 227                                     -1, "Trailing junk");
 228
 229         return;
 230 }
 231
 232 /* Both Source-Active and Source-Active Response have the same format
 233  * with one exception. Encapsulated multicast data is not allowed in
 234  * SA Response.
 235  */
 236 static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo,
 237     proto_tree *tree, int *offset, int length)
 238 {
 239         guint8 entries;
 240
 241         if (length < 1)
 242                 return;
 243         entries = tvb_get_guint8(tvb, *offset);
 244         proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
 245         *offset += 1;
 246         length -= 1;
 247
 248         if (length < 4) {
 249                 *offset += length;
 250                 return;
 251         }
 252         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
 253         *offset += 4;
 254         length -= 4;
 255
 256         /* Put each of the (S,G) entries in their own subtree.
 257          * This is probably visually better.
 258          */
 259         while (entries-- > 0) {
 260                 proto_item *ei;
 261                 proto_tree *entry_tree;
 262
 263                 if (length < 12) {
 264                         *offset += length;
 265                         return;
 266                 }
 267                 ei = proto_tree_add_text(tree, tvb, *offset, 12, "(S,G) block: %s/%u -> %s",
 268                                          tvb_ip_to_str(tvb, *offset + 8),
 269                                          tvb_get_guint8(tvb, *offset + 3),
 270                                          tvb_ip_to_str(tvb, *offset + 4));
 271                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 272
 273                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, ENC_BIG_ENDIAN);
 274                 *offset += 3;
 275                 length -= 3;
 276                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, ENC_BIG_ENDIAN);
 277                 *offset += 1;
 278                 length -= 1;
 279                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
 280                 *offset += 4;
 281                 length -= 4;
 282                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
 283                 *offset += 4;
 284                 length -= 4;
 285         }
 286
 287         /*
 288          * Check if an encapsulated multicast IPv4 packet follows
 289          */
 290         if (length > 0) {
 291                 proto_item *ei;
 292                 proto_tree *enc_tree;
 293                 gint available_length, reported_length;
 294                 tvbuff_t *next_tvb;
 295
 296                 ei = proto_tree_add_text(tree, tvb, *offset, length,
 297                                          "Encapsulated IPv4 packet: %u bytes",
 298                                          length);
 299                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 300
 301                 available_length = tvb_length_remaining(tvb, *offset);
 302                 reported_length = tvb_reported_length_remaining(tvb, *offset);
 303                 DISSECTOR_ASSERT(available_length >= 0);
 304                 DISSECTOR_ASSERT(reported_length >= 0);
 305                 if (available_length > reported_length)
 306                         available_length = reported_length;
 307                 if (available_length > length)
 308                         available_length = length;
 309                 if (reported_length > length)
 310                         reported_length = length;
 311
 312                 next_tvb = tvb_new_subset(tvb, *offset, available_length,
 313                                           reported_length);
 314                 /* Set the information columns read-only so that they
 315                  * reflect the MSDP packet rather than the
 316                  * encapsulated packet.
 317                  */
 318                 col_set_writable(pinfo->cinfo, FALSE);
 319                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 320         }
 321         *offset += length;
 322
 323         return;
 324 }
 325
 326 /* Note: updates *offset */
 327 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 328 {
 329         guint32 ipaddr;
 330
 331         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, ENC_BIG_ENDIAN);
 332         *offset += 3;
 333         ipaddr = tvb_get_ipv4(tvb, *offset);
 334         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 335                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 336         *offset += 4;
 337
 338         return;
 339 }
 340
 341 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 342 {
 343         guint8              error, error_sub;
 344         const value_string *vals;
 345
 346         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, ENC_BIG_ENDIAN);
 347         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, ENC_BIG_ENDIAN);
 348         error = tvb_get_guint8(tvb, *offset);
 349         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 350         *offset += 1;
 351
 352         /* Depending on the Error Code, we collect the correct
 353          * value_strings for the Error subcode
 354          */
 355         switch (error) {
 356         case MESSAGE_HEADER_ERROR:
 357                 vals = hdr_error_vals;
 358                 break;
 359         case SA_REQUEST_ERROR:
 360                 vals = sa_req_error_vals;
 361                 break;
 362         case SA_MESSAGE_SA_RESPONSE_ERROR:
 363                 vals = sa_msg_error_vals;
 364                 break;
 365         case FSM_ERROR:
 366                 vals = fsm_error_vals;
 367                 break;
 368         case HOLD_TIMER_EXPIRED:
 369         case NOTIFICATION:
 370         case CEASE:
 371                 vals = sa_unspec_error_vals;
 372                 break;
 373         default:
 374                 vals = sa_unspec_error_vals;
 375                 break;
 376         }
 377
 378         error_sub = tvb_get_guint8(tvb, *offset);
 379         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 380                                    error_sub, "Error subcode: %s (%u)",
 381                                    val_to_str_const(error_sub, vals, "<Unknown Error subcode>"),
 382                                    error_sub);
 383         *offset += 1;
 384
 385         /* Do switch again, this time to dissect the data portion
 386          * correctly. Ugly.
 387          */
 388         switch (error) {
 389                 tvbuff_t *next_tvb;
 390         case SA_REQUEST_ERROR:
 391                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 392                 break;
 393         case SA_MESSAGE_SA_RESPONSE_ERROR:
 394                 if (error_sub == 0) {
 395                         break;
 396                 } else if (error_sub == 1) {
 397                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, ENC_BIG_ENDIAN);
 398                         *offset += 1;
 399                         break;
 400                 } else if (error_sub == 2) {
 401                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 402                         break;
 403                 } else if (error_sub == 3 || error_sub == 8) {
 404                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 405                         break;
 406                 } else if (error_sub == 4) {
 407                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 408                         break;
 409                 } else if (error_sub == 5) {
 410                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, ENC_BIG_ENDIAN);
 411                         *offset += 1;
 412                         break;
 413                 } else if (error_sub == 6) {
 414                         /* No break, causes fall through to next label */
 415                 } else if (error_sub == 7) {
 416                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 417                                             "Packet with unknown encapsulation: %u bytes",
 418                                             tlv_len - 5);
 419                         *offset += tlv_len - 5;
 420                         break;
 421                 } else {
 422                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 423                                             "<Unknown data>: %u bytes",
 424                                             tlv_len -5);
 425                         *offset += tlv_len - 5;
 426                         break;
 427                 }
 428                 /* Fall through */
 429         case MESSAGE_HEADER_ERROR:
 430         case NOTIFICATION:
 431                 /* Data contains the message that had an error. Even a
 432                  * broken Notification message causes a Notification
 433                  * message with Error Code set to Notification to be
 434                  * sent back.
 435                  */
 436                 next_tvb = tvb_new_subset_remaining(tvb, *offset);
 437                 dissect_msdp(next_tvb, pinfo, tree);
 438                 break;
 439         case FSM_ERROR:
 440         case HOLD_TIMER_EXPIRED:
 441         case CEASE:
 442                 /* Do nothing. These contain no data */
 443                 break;
 444         default:
 445                 if (tlv_len - 5 > 0)
 446                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 447                                     "<Unknown data>: %u bytes",
 448                                     tlv_len -5);
 449                 *offset += tlv_len - 5;
 450                 break;
 451         }
 452
 453         return;
 454 }
 455
 456 void
 457 proto_register_msdp(void)
 458 {
 459         static hf_register_info hf[] = {
 460                 { &hf_msdp_type,
 461                         { "Type",           "msdp.type",
 462                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 463                         "MSDP TLV type", HFILL }
 464                 },
 465                 { &hf_msdp_length,
 466                         { "Length",           "msdp.length",
 467                         FT_UINT16, BASE_DEC, NULL, 0,
 468                         "MSDP TLV Length", HFILL }
 469                 },
 470                 { &hf_msdp_sa_entry_count,
 471                         { "Entry Count",           "msdp.sa.entry_count",
 472                         FT_UINT8, BASE_DEC, NULL, 0,
 473                         "MSDP SA Entry Count", HFILL }
 474                 },
 475                 { &hf_msdp_sa_rp_addr,
 476                         { "RP Address",           "msdp.sa.rp_addr",
 477                         FT_IPv4, BASE_NONE, NULL, 0,
 478                         "Active source's RP address", HFILL }
 479                 },
 480                 { &hf_msdp_sa_reserved,
 481                         { "Reserved",           "msdp.sa.reserved",
 482                         FT_UINT24, BASE_HEX, NULL, 0,
 483                         "Transmitted as zeros and ignored by a receiver", HFILL }
 484                 },
 485                 { &hf_msdp_sa_sprefix_len,
 486                         { "Sprefix len",           "msdp.sa.sprefix_len",
 487                         FT_UINT8, BASE_DEC, NULL, 0,
 488                         "The route prefix length associated with source address", HFILL }
 489                 },
 490                 { &hf_msdp_sa_group_addr,
 491                         { "Group Address",           "msdp.sa.group_addr",
 492                         FT_IPv4, BASE_NONE, NULL, 0,
 493                         "The group address the active source has sent data to", HFILL }
 494                 },
 495                 { &hf_msdp_sa_src_addr,
 496                         { "Source Address",           "msdp.sa.src_addr",
 497                         FT_IPv4, BASE_NONE, NULL, 0,
 498                         "The IP address of the active source", HFILL }
 499                 },
 500                 { &hf_msdp_sa_req_res,
 501                         { "Reserved",           "msdp.sa_req.res",
 502                         FT_UINT8, BASE_HEX, NULL, 0,
 503                         "Transmitted as zeros and ignored by a receiver", HFILL }
 504                 },
 505                 { &hf_msdp_sa_req_group,
 506                         { "Group Address",           "msdp.sa_req.group_addr",
 507                         FT_IPv4, BASE_NONE, NULL, 0,
 508                         "The group address the MSDP peer is requesting", HFILL }
 509                 },
 510                 { &hf_msdp_not_o,
 511                         { "Open-bit",           "msdp.not.o",
 512                         FT_UINT8, BASE_HEX, NULL, 0x80,
 513                         "If clear, the connection will be closed", HFILL }
 514                 },
 515                 { &hf_msdp_not_error,
 516                         { "Error Code",           "msdp.not.error",
 517                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 518                         "Indicates the type of Notification", HFILL }
 519                 },
 520                 { &hf_msdp_not_error_sub,
 521                         { "Error subode",           "msdp.not.error_sub",
 522                         FT_UINT8, BASE_DEC, NULL, 0,
 523                         "Error subcode", HFILL }
 524                 },
 525                 { &hf_msdp_not_ipv4,
 526                         { "IPv4 address",           "msdp.not.ipv4",
 527                         FT_IPv4, BASE_NONE, NULL, 0,
 528                         "Group/RP/Source address in Notification messages", HFILL }
 529                 },
 530                 { &hf_msdp_not_res,
 531                         { "Reserved",           "msdp.not.res",
 532                         FT_UINT24, BASE_HEX, NULL, 0,
 533                         "Reserved field in Notification messages", HFILL }
 534                 },
 535                 { &hf_msdp_not_entry_count,
 536                         { "Entry Count",           "msdp.not.entry_count",
 537                         FT_UINT24, BASE_HEX, NULL, 0,
 538                         "Entry Count in Notification messages", HFILL }
 539                 },
 540                 { &hf_msdp_not_sprefix_len,
 541                         { "Sprefix len",           "msdp.not.sprefix_len",
 542                         FT_UINT8, BASE_DEC, NULL, 0,
 543                         "Source prefix length in Notification messages", HFILL }
 544                 },
 545         };
 546
 547         static gint *ett[] = {
 548                 &ett_msdp,
 549                 &ett_msdp_sa_entry,
 550                 &ett_msdp_sa_enc_data,
 551                 &ett_msdp_not_data,
 552         };
 553
 554         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 555             "MSDP", "msdp");
 556
 557         proto_register_field_array(proto_msdp, hf, array_length(hf));
 558         proto_register_subtree_array(ett, array_length(ett));
 559 }
 560
 561 void
 562 proto_reg_handoff_msdp(void)
 563 {
 564         dissector_handle_t msdp_handle;
 565
 566         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 567         dissector_add_uint("tcp.port", 639, msdp_handle);
 568
 569         ip_handle = find_dissector("ip");
 570
 571         return;
 572 }