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 1.7 2002/08/02 23:35:54 jmayer 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, int *offset);
 173 static void
 174 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 175
 176
 177 static void
 178 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 179 {
 180         proto_item *ti;
 181         proto_tree *msdp_tree;
 182         int offset;
 183
 184         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 185                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 186
 187         if (check_col(pinfo->cinfo, COL_INFO))
 188                 col_set_str(pinfo->cinfo, COL_INFO, val_to_str(tvb_get_guint8(tvb, 0),
 189                                                             msdp_types,
 190                                                             "<Unknown MSDP message type>"));
 191
 192         if (tree) {
 193                 guint8 type;
 194                 guint16 length;
 195
 196                 ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, FALSE);
 197                 msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 198
 199                 offset = 0;
 200                 while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 201                         type = tvb_get_guint8(tvb, offset);
 202                         length = tvb_get_ntohs(tvb, offset + 1);
 203                         if (length < 3)
 204                                 break;
 205                         proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 206                         proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 207                         offset += 3;
 208
 209                         switch (type) {
 210                         case MSDP_SA:
 211                         case MSDP_SA_RSP:
 212                                 dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset);
 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 > 3)
 224                                         proto_tree_add_text(msdp_tree, tvb, offset, length - 3, "TLV contents");
 225                                 offset += (length - 3);
 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, proto_tree *tree, int *offset)
 243 {
 244         guint8 entries;
 245         guint32 rp_addr;
 246
 247         entries = tvb_get_guint8(tvb, *offset);
 248         proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
 249         *offset += 1;
 250
 251         tvb_memcpy(tvb, (guint8 *)&rp_addr, *offset, 4);
 252         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, FALSE);
 253         *offset += 4;
 254
 255         /* Put each of the (S,G) entries in their own subtree.
 256          * This is probably visually better.
 257          */
 258         while (entries-- > 0) {
 259                 proto_item *ei;
 260                 proto_tree *entry_tree;
 261
 262                 ei = proto_tree_add_text(tree, tvb, *offset, 24, "(S,G) block: %s/%u -> %s",
 263                                          ip_to_str(tvb_get_ptr(tvb, *offset + 8, 4)),
 264                                          tvb_get_guint8(tvb, *offset + 3),
 265                                          ip_to_str(tvb_get_ptr(tvb, *offset + 4, 4)));
 266                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 267
 268                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, FALSE);
 269                 *offset += 3;
 270                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, FALSE);
 271                 *offset += 1;
 272                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, FALSE);
 273                 *offset += 4;
 274                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, FALSE);
 275                 *offset += 4;
 276         }
 277
 278         /*
 279          * Check if an encapsulated multicast IPv4 packet follows
 280          */
 281         if (tvb_reported_length_remaining(tvb, *offset) > 0) {
 282                 proto_item *ei;
 283                 proto_tree *enc_tree;
 284                 tvbuff_t *next_tvb;
 285
 286                 ei = proto_tree_add_text(tree, tvb, *offset, -1,
 287                                          "Encapsulated IPv4 packet: %u bytes",
 288                                          tvb_reported_length_remaining(tvb, *offset));
 289                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 290
 291                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 292                 /* Set the information columns read-only so that they
 293                  * reflect the MSDP packet rather than the
 294                  * encapsulated packet.
 295                  */
 296                 col_set_writable(pinfo->cinfo, FALSE);
 297                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 298         }
 299         *offset += tvb_length_remaining(tvb, *offset);
 300
 301         return;
 302 }
 303
 304 /* Note: updates *offset */
 305 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 306 {
 307         guint32 ipaddr;
 308
 309         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, FALSE);
 310         *offset += 3;
 311         tvb_memcpy(tvb, (guint8 *)&ipaddr, *offset, 4);
 312         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 313                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 314         *offset += 4;
 315
 316         return;
 317 }
 318
 319 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 320 {
 321         guint8 error, error_sub;
 322         const value_string *vals;
 323
 324         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, FALSE);
 325         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, FALSE);
 326         error = tvb_get_guint8(tvb, *offset);
 327         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 328         *offset += 1;
 329
 330         /* Depending on the Error Code, we collect the correct
 331          * value_strings for the Error subcode
 332          */
 333         switch (error) {
 334         case MESSAGE_HEADER_ERROR:
 335                 vals = hdr_error_vals;
 336                 break;
 337         case SA_REQUEST_ERROR:
 338                 vals = sa_req_error_vals;
 339                 break;
 340         case SA_MESSAGE_SA_RESPONSE_ERROR:
 341                 vals = sa_msg_error_vals;
 342                 break;
 343         case FSM_ERROR:
 344                 vals = fsm_error_vals;
 345                 break;
 346         case HOLD_TIMER_EXPIRED:
 347         case NOTIFICATION:
 348         case CEASE:
 349                 vals = sa_unspec_error_vals;
 350                 break;
 351         default:
 352                 vals = sa_unspec_error_vals;
 353                 break;
 354         }
 355
 356         error_sub = tvb_get_guint8(tvb, *offset);
 357         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 358                                    error_sub, "Error subcode: %s (%u)",
 359                                    val_to_str(error_sub, vals, "<Unknown Error subcode>"),
 360                                    error_sub);
 361         *offset += 1;
 362
 363         /* Do switch again, this time to dissect the data portion
 364          * correctly. Ugly.
 365          */
 366         switch (error) {
 367                 tvbuff_t *next_tvb;
 368         case SA_REQUEST_ERROR:
 369                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 370                 break;
 371         case SA_MESSAGE_SA_RESPONSE_ERROR:
 372                 if (error_sub == 0) {
 373                         break;
 374                 } else if (error_sub == 1) {
 375                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, FALSE);
 376                         *offset += 1;
 377                         break;
 378                 } else if (error_sub == 2) {
 379                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 380                         break;
 381                 } else if (error_sub == 3 || error_sub == 8) {
 382                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 383                         break;
 384                 } else if (error_sub == 4) {
 385                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 386                         break;
 387                 } else if (error_sub == 5) {
 388                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, FALSE);
 389                         *offset += 1;
 390                         break;
 391                 } else if (error_sub == 6) {
 392                         /* No break, causes fall through to next label */
 393                 } else if (error_sub == 7) {
 394                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 395                                             "Packet with unknown encapsulation: %u bytes",
 396                                             tlv_len - 5);
 397                         *offset += tlv_len - 5;
 398                         break;
 399                 } else {
 400                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 401                                             "<Unknown data>: %u bytes",
 402                                             tlv_len -5);
 403                         *offset += tlv_len - 5;
 404                         break;
 405                 }
 406                 /* Fall through */
 407         case MESSAGE_HEADER_ERROR:
 408         case NOTIFICATION:
 409                 /* Data contains the message that had an error. Even a
 410                  * broken Notification message causes a Notification
 411                  * message with Error Code set to Notification to be
 412                  * sent back.
 413                  */
 414                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 415                 dissect_msdp(next_tvb, pinfo, tree);
 416                 break;
 417         case FSM_ERROR:
 418         case HOLD_TIMER_EXPIRED:
 419         case CEASE:
 420                 /* Do nothing. These contain no data */
 421                 break;
 422         default:
 423                 if (tlv_len - 5 > 0)
 424                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 425                                     "<Unknown data>: %u bytes",
 426                                     tlv_len -5);
 427                 *offset += tlv_len - 5;
 428                 break;
 429         }
 430
 431         return;
 432 }
 433
 434 void
 435 proto_register_msdp(void)
 436 {
 437         static hf_register_info hf[] = {
 438                 { &hf_msdp_type,
 439                         { "Type",           "msdp.type",
 440                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 441                         "MSDP TLV type", HFILL }
 442                 },
 443                 { &hf_msdp_length,
 444                         { "Length",           "msdp.length",
 445                         FT_UINT16, BASE_DEC, NULL, 0,
 446                         "MSDP TLV Length", HFILL }
 447                 },
 448                 { &hf_msdp_sa_entry_count,
 449                         { "Entry Count",           "msdp.sa.entry_count",
 450                         FT_UINT8, BASE_DEC, NULL, 0,
 451                         "MSDP SA Entry Count", HFILL }
 452                 },
 453                 { &hf_msdp_sa_rp_addr,
 454                         { "RP Address",           "msdp.sa.rp_addr",
 455                         FT_IPv4, 0, NULL, 0,
 456                         "Active source's RP address", HFILL }
 457                 },
 458                 { &hf_msdp_sa_reserved,
 459                         { "Reserved",           "msdp.sa.reserved",
 460                         FT_UINT24, BASE_HEX, NULL, 0,
 461                         "Transmitted as zeros and ignored by a receiver", HFILL }
 462                 },
 463                 { &hf_msdp_sa_sprefix_len,
 464                         { "Sprefix len",           "msdp.sa.sprefix_len",
 465                         FT_UINT8, BASE_DEC, NULL, 0,
 466                         "The route prefix length associated with source address", HFILL }
 467                 },
 468                 { &hf_msdp_sa_group_addr,
 469                         { "Group Address",           "msdp.sa.group_addr",
 470                         FT_IPv4, 0, NULL, 0,
 471                         "The group address the active source has sent data to", HFILL }
 472                 },
 473                 { &hf_msdp_sa_src_addr,
 474                         { "Source Address",           "msdp.sa.src_addr",
 475                         FT_IPv4, 0, NULL, 0,
 476                         "The IP address of the active source", HFILL }
 477                 },
 478                 { &hf_msdp_sa_req_res,
 479                         { "Reserved",           "msdp.sa_req.res",
 480                         FT_UINT8, BASE_HEX, NULL, 0,
 481                         "Transmitted as zeros and ignored by a receiver", HFILL }
 482                 },
 483                 { &hf_msdp_sa_req_group,
 484                         { "Group Address",           "msdp.sa_req.group_addr",
 485                         FT_IPv4, 0, NULL, 0,
 486                         "The group address the MSDP peer is requesting", HFILL }
 487                 },
 488                 { &hf_msdp_not_o,
 489                         { "Open-bit",           "msdp.not.o",
 490                         FT_UINT8, BASE_HEX, NULL, 0x80,
 491                         "If clear, the connection will be closed", HFILL }
 492                 },
 493                 { &hf_msdp_not_error,
 494                         { "Error Code",           "msdp.not.error",
 495                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 496                         "Indicates the type of Notification", HFILL }
 497                 },
 498                 { &hf_msdp_not_error_sub,
 499                         { "Error subode",           "msdp.not.error_sub",
 500                         FT_UINT8, BASE_DEC, NULL, 0,
 501                         "Error subcode", HFILL }
 502                 },
 503                 { &hf_msdp_not_ipv4,
 504                         { "IPv4 address",           "msdp.not.ipv4",
 505                         FT_IPv4, 0, NULL, 0,
 506                         "Group/RP/Source address in Notification messages", HFILL }
 507                 },
 508                 { &hf_msdp_not_res,
 509                         { "Reserved",           "msdp.not.res",
 510                         FT_UINT24, BASE_HEX, NULL, 0,
 511                         "Reserved field in Notification messages", HFILL }
 512                 },
 513                 { &hf_msdp_not_entry_count,
 514                         { "Entry Count",           "msdp.not.entry_count",
 515                         FT_UINT24, BASE_HEX, NULL, 0,
 516                         "Entry Count in Notification messages", HFILL }
 517                 },
 518                 { &hf_msdp_not_sprefix_len,
 519                         { "Sprefix len",           "msdp.not.sprefix_len",
 520                         FT_UINT8, BASE_DEC, NULL, 0,
 521                         "Source prefix length in Notification messages", HFILL }
 522                 },
 523         };
 524
 525         static gint *ett[] = {
 526                 &ett_msdp,
 527                 &ett_msdp_sa_entry,
 528                 &ett_msdp_sa_enc_data,
 529                 &ett_msdp_not_data,
 530         };
 531
 532         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 533             "MSDP", "msdp");
 534
 535         proto_register_field_array(proto_msdp, hf, array_length(hf));
 536         proto_register_subtree_array(ett, array_length(ett));
 537 }
 538
 539 void
 540 proto_reg_handoff_msdp(void)
 541 {
 542         dissector_handle_t msdp_handle;
 543
 544         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 545         dissector_add("tcp.port", 639, msdp_handle);
 546
 547         ip_handle = find_dissector("ip");
 548
 549         return;
 550 }