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 1.6 2002/01/24 09:20:49 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 #ifdef HAVE_SYS_TYPES_H
  37 # include <sys/types.h>
  38 #endif
  39
  40 #ifdef HAVE_NETINET_IN_H
  41 # include <netinet/in.h>
  42 #endif
  43 #include <glib.h>
  44
  45 #include <epan/packet.h>
  46
  47 /* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
  48 enum { MSDP_SA     = 1,
  49        MSDP_SA_REQ,
  50        MSDP_SA_RSP,
  51        MSDP_KEEP_ALIVE,
  52        MSDP_NOTIFICATION,
  53
  54        /* Theses are only assigned in MSDP spec. Their use is specifed
  55         * elsewhere */
  56        MSDP_TRACE_IN_PROGRESS,
  57        MSDP_TRACE_REPLY
  58 };
  59
  60 static const value_string msdp_types[] = {
  61         { MSDP_SA,                "IPv4 Source-Active"           },
  62         { MSDP_SA_REQ,            "IPv4 Source-Active Request"   },
  63         { MSDP_SA_RSP,            "IPv4 Source-Active Response"  },
  64         { MSDP_KEEP_ALIVE,        "KeepAlive"                    },
  65         { MSDP_NOTIFICATION,      "Notification"                 },
  66
  67         { MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progresss" },
  68         { MSDP_TRACE_REPLY,       "MSDP traceroute reply"        },
  69         { 0, NULL },
  70 };
  71
  72
  73 /* Error codes */
  74 enum { MESSAGE_HEADER_ERROR = 1,
  75        SA_REQUEST_ERROR,
  76        SA_MESSAGE_SA_RESPONSE_ERROR,
  77        HOLD_TIMER_EXPIRED,
  78        FSM_ERROR,
  79        NOTIFICATION,
  80        CEASE
  81 };
  82
  83 static const value_string error_vals[] = {
  84         { MESSAGE_HEADER_ERROR,         "Message Header Error"         },
  85         { SA_REQUEST_ERROR,             "SA-Request Error"             },
  86         { SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
  87         { HOLD_TIMER_EXPIRED,           "Hold Timer Expired"           },
  88         { FSM_ERROR,                    "Finite State Machine Error"   },
  89         { NOTIFICATION,                 "Notification"                 },
  90         { CEASE,                        "Cease"                        },
  91         { 0, NULL },
  92 };
  93
  94
  95 /* Message Header Error subcodes */
  96 static const value_string hdr_error_vals[] = {
  97         { 0, "Unspecific"         },
  98         { 2, "Bad Message Length" },
  99         { 3, "Bad Message Type"   },
 100         { 0, NULL },
 101 };
 102
 103 /* SA-Request Error subcodes (the O-bit is always clear) */
 104 static const value_string sa_req_error_vals[] = {
 105         { 0, "Unspecific"    },
 106         { 1, "Invalid Group" },
 107         { 0, NULL },
 108 };
 109
 110 /* SA-Message/SA-Response Error subcodes */
 111 static const value_string sa_msg_error_vals[] = {
 112         { 0, "Unspecific"                             },
 113         { 1, "Invalid Entry Count"                    },
 114         { 2, "Invalid RP Address"                     },
 115         { 3, "Invalid Group Address"                  },
 116         { 4, "Invalid Source Address"                 },
 117         { 5, "Invalid Sprefix Length"                 },
 118         { 6, "Looping SA (Self is RP)"                },
 119         { 7, "Unknown Encapsulation"                  },
 120         { 8, "Administrative Scope Boundary Violated" },
 121         { 0, NULL },
 122 };
 123
 124 /* Finite State Machine Error subcodes (the O-bit is always clear) */
 125 static const value_string fsm_error_vals[] = {
 126         { 0, "Unspecific"                        },
 127         { 1, "Unexpected Message Type FSM Error" },
 128         { 0, NULL },
 129 };
 130
 131 /*
 132  * Hold Timer Expired subcodes (the O-bit is always clear):
 133  * Notification subcodes (the O-bit is always clear):
 134  * Cease subcodes (the O-bit is always clear):
 135  *
 136  * These have only "Unspecific" specified.
 137  */
 138 static const value_string sa_unspec_error_vals[] = {
 139         { 0, "Unspecific" },
 140         { 0, NULL },
 141 };
 142
 143
 144 /* Initialize the protocol and registered fields */
 145 static int proto_msdp = -1;
 146 static int hf_msdp_type = -1;
 147 static int hf_msdp_length = -1;
 148
 149 static int hf_msdp_sa_entry_count = -1;
 150 static int hf_msdp_sa_rp_addr = -1;
 151 static int hf_msdp_sa_reserved = -1;
 152 static int hf_msdp_sa_sprefix_len = -1;
 153 static int hf_msdp_sa_group_addr = -1;
 154 static int hf_msdp_sa_src_addr = -1;
 155
 156 static int hf_msdp_sa_req_res = -1;
 157 static int hf_msdp_sa_req_group = -1;
 158
 159 static int hf_msdp_not_o = -1;
 160 static int hf_msdp_not_error = -1;
 161 static int hf_msdp_not_error_sub = -1;
 162
 163 static int hf_msdp_not_ipv4 = -1;
 164 static int hf_msdp_not_res = -1;
 165 static int hf_msdp_not_entry_count = -1;
 166 static int hf_msdp_not_sprefix_len = -1;
 167
 168
 169 static gint ett_msdp = -1;
 170 static gint ett_msdp_sa_entry = -1;
 171 static gint ett_msdp_sa_enc_data = -1;
 172 static gint ett_msdp_not_data = -1;
 173
 174
 175 static dissector_handle_t ip_handle;
 176
 177
 178 static void
 179 dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset);
 180 static void
 181 dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
 182
 183
 184 static void
 185 dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 186 {
 187         proto_item *ti;
 188         proto_tree *msdp_tree;
 189         int offset;
 190
 191         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 192                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
 193
 194         if (check_col(pinfo->cinfo, COL_INFO))
 195                 col_set_str(pinfo->cinfo, COL_INFO, val_to_str(tvb_get_guint8(tvb, 0),
 196                                                             msdp_types,
 197                                                             "<Unknown MSDP message type>"));
 198
 199         if (tree) {
 200                 guint8 type;
 201                 guint16 length;
 202
 203                 ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, FALSE);
 204                 msdp_tree = proto_item_add_subtree(ti, ett_msdp);
 205
 206                 offset = 0;
 207                 while (tvb_reported_length_remaining(tvb, offset) >= 3) {
 208                         type = tvb_get_guint8(tvb, offset);
 209                         length = tvb_get_ntohs(tvb, offset + 1);
 210                         if (length < 3)
 211                                 break;
 212                         proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
 213                         proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
 214                         offset += 3;
 215
 216                         switch (type) {
 217                         case MSDP_SA:
 218                         case MSDP_SA_RSP:
 219                                 dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset);
 220                                 break;
 221                         case MSDP_SA_REQ:
 222                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, FALSE);
 223                                 proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, FALSE);
 224                                 offset += 5;
 225                                 break;
 226                         case MSDP_NOTIFICATION:
 227                                 dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
 228                                 break;
 229                         default:
 230                                 if (length > 3)
 231                                         proto_tree_add_text(msdp_tree, tvb, offset, length - 3, "TLV contents");
 232                                 offset += (length - 3);
 233                                 break;
 234                         }
 235                 }
 236
 237                 if (tvb_length_remaining(tvb, offset) > 0)
 238                         proto_tree_add_text(msdp_tree, tvb, offset,
 239                                             -1, "Trailing junk");
 240         }
 241
 242         return;
 243 }
 244
 245 /* Both Source-Active and Source-Active Response have the same format
 246  * with one exception. Encapsulated multicast data is not allowed in
 247  * SA Response.
 248  */
 249 static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset)
 250 {
 251         guint8 entries;
 252         guint32 rp_addr;
 253
 254         entries = tvb_get_guint8(tvb, *offset);
 255         proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
 256         *offset += 1;
 257
 258         tvb_memcpy(tvb, (guint8 *)&rp_addr, *offset, 4);
 259         proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, FALSE);
 260         *offset += 4;
 261
 262         /* Put each of the (S,G) entries in their own subtree.
 263          * This is probably visually better.
 264          */
 265         while (entries-- > 0) {
 266                 proto_item *ei;
 267                 proto_tree *entry_tree;
 268
 269                 ei = proto_tree_add_text(tree, tvb, *offset, 24, "(S,G) block: %s/%u -> %s",
 270                                          ip_to_str(tvb_get_ptr(tvb, *offset + 8, 4)),
 271                                          tvb_get_guint8(tvb, *offset + 3),
 272                                          ip_to_str(tvb_get_ptr(tvb, *offset + 4, 4)));
 273                 entry_tree = proto_item_add_subtree(ei, ett_msdp_sa_entry);
 274
 275                 proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, FALSE);
 276                 *offset += 3;
 277                 proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, FALSE);
 278                 *offset += 1;
 279                 proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, FALSE);
 280                 *offset += 4;
 281                 proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, FALSE);
 282                 *offset += 4;
 283         }
 284
 285         /*
 286          * Check if an encapsulated multicast IPv4 packet follows
 287          */
 288         if (tvb_reported_length_remaining(tvb, *offset) > 0) {
 289                 proto_item *ei;
 290                 proto_tree *enc_tree;
 291                 tvbuff_t *next_tvb;
 292
 293                 ei = proto_tree_add_text(tree, tvb, *offset, -1,
 294                                          "Encapsulated IPv4 packet: %u bytes",
 295                                          tvb_reported_length_remaining(tvb, *offset));
 296                 enc_tree = proto_item_add_subtree(ei, ett_msdp_sa_enc_data);
 297
 298                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 299                 /* Set the information columns read-only so that they
 300                  * reflect the MSDP packet rather than the
 301                  * encapsulated packet.
 302                  */
 303                 col_set_writable(pinfo->cinfo, FALSE);
 304                 call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
 305         }
 306         *offset += tvb_length_remaining(tvb, *offset);
 307
 308         return;
 309 }
 310
 311 /* Note: updates *offset */
 312 static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, const char *addrtype)
 313 {
 314         guint32 ipaddr;
 315
 316         proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, FALSE);
 317         *offset += 3;
 318         tvb_memcpy(tvb, (guint8 *)&ipaddr, *offset, 4);
 319         proto_tree_add_ipv4_format(tree, hf_msdp_not_ipv4, tvb, *offset, 4, ipaddr,
 320                                    "%s: %s", addrtype, ip_to_str((guint8 *)&ipaddr));
 321         *offset += 4;
 322
 323         return;
 324 }
 325
 326 static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
 327 {
 328         guint8 error, error_sub;
 329         const value_string *vals;
 330
 331         proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, FALSE);
 332         proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, FALSE);
 333         error = tvb_get_guint8(tvb, *offset);
 334         error &= 0x7F;             /* Error is 7-bit field. O-bit is bit 8 */
 335         *offset += 1;
 336
 337         /* Depending on the Error Code, we collect the correct
 338          * value_strings for the Error subcode
 339          */
 340         switch (error) {
 341         case MESSAGE_HEADER_ERROR:
 342                 vals = hdr_error_vals;
 343                 break;
 344         case SA_REQUEST_ERROR:
 345                 vals = sa_req_error_vals;
 346                 break;
 347         case SA_MESSAGE_SA_RESPONSE_ERROR:
 348                 vals = sa_msg_error_vals;
 349                 break;
 350         case FSM_ERROR:
 351                 vals = fsm_error_vals;
 352                 break;
 353         case HOLD_TIMER_EXPIRED:
 354         case NOTIFICATION:
 355         case CEASE:
 356                 vals = sa_unspec_error_vals;
 357                 break;
 358         default:
 359                 vals = sa_unspec_error_vals;
 360                 break;
 361         }
 362
 363         error_sub = tvb_get_guint8(tvb, *offset);
 364         proto_tree_add_uint_format(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
 365                                    error_sub, "Error subcode: %s (%u)",
 366                                    val_to_str(error_sub, vals, "<Unknown Error subcode>"),
 367                                    error_sub);
 368         *offset += 1;
 369
 370         /* Do switch again, this time to dissect the data portion
 371          * correctly. Ugly.
 372          */
 373         switch (error) {
 374                 tvbuff_t *next_tvb;
 375         case SA_REQUEST_ERROR:
 376                 add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 377                 break;
 378         case SA_MESSAGE_SA_RESPONSE_ERROR:
 379                 if (error_sub == 0) {
 380                         break;
 381                 } else if (error_sub == 1) {
 382                         proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, FALSE);
 383                         *offset += 1;
 384                         break;
 385                 } else if (error_sub == 2) {
 386                         add_notification_data_ipv4addr(tvb, tree, offset, "RP address");
 387                         break;
 388                 } else if (error_sub == 3 || error_sub == 8) {
 389                         add_notification_data_ipv4addr(tvb, tree, offset, "Group address");
 390                         break;
 391                 } else if (error_sub == 4) {
 392                         add_notification_data_ipv4addr(tvb, tree, offset, "Source address");
 393                         break;
 394                 } else if (error_sub == 5) {
 395                         proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, FALSE);
 396                         *offset += 1;
 397                         break;
 398                 } else if (error_sub == 6) {
 399                         /* No break, causes fall through to next label */
 400                 } else if (error_sub == 7) {
 401                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 402                                             "Packet with unknown encapsulation: %u bytes",
 403                                             tlv_len - 5);
 404                         *offset += tlv_len - 5;
 405                         break;
 406                 } else {
 407                         proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 408                                             "<Unknown data>: %u bytes",
 409                                             tlv_len -5);
 410                         *offset += tlv_len - 5;
 411                         break;
 412                 }
 413                 /* Fall through */
 414         case MESSAGE_HEADER_ERROR:
 415         case NOTIFICATION:
 416                 /* Data contains the message that had an error. Even a
 417                  * broken Notification message causes a Notification
 418                  * message with Error Code set to Notification to be
 419                  * sent back.
 420                  */
 421                 next_tvb = tvb_new_subset(tvb, *offset, -1, -1);
 422                 dissect_msdp(next_tvb, pinfo, tree);
 423                 break;
 424         case FSM_ERROR:
 425         case HOLD_TIMER_EXPIRED:
 426         case CEASE:
 427                 /* Do nothing. These contain no data */
 428                 break;
 429         default:
 430                 if (tlv_len - 5 > 0)
 431                 proto_tree_add_text(tree, tvb, *offset, tlv_len - 5,
 432                                     "<Unknown data>: %u bytes",
 433                                     tlv_len -5);
 434                 *offset += tlv_len - 5;
 435                 break;
 436         }
 437
 438         return;
 439 }
 440
 441 void
 442 proto_register_msdp(void)
 443 {
 444         static hf_register_info hf[] = {
 445                 { &hf_msdp_type,
 446                         { "Type",           "msdp.type",
 447                         FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
 448                         "MSDP TLV type", HFILL }
 449                 },
 450                 { &hf_msdp_length,
 451                         { "Length",           "msdp.length",
 452                         FT_UINT16, BASE_DEC, NULL, 0,
 453                         "MSDP TLV Length", HFILL }
 454                 },
 455                 { &hf_msdp_sa_entry_count,
 456                         { "Entry Count",           "msdp.sa.entry_count",
 457                         FT_UINT8, BASE_DEC, NULL, 0,
 458                         "MSDP SA Entry Count", HFILL }
 459                 },
 460                 { &hf_msdp_sa_rp_addr,
 461                         { "RP Address",           "msdp.sa.rp_addr",
 462                         FT_IPv4, 0, NULL, 0,
 463                         "Active source's RP address", HFILL }
 464                 },
 465                 { &hf_msdp_sa_reserved,
 466                         { "Reserved",           "msdp.sa.reserved",
 467                         FT_UINT24, BASE_HEX, NULL, 0,
 468                         "Transmitted as zeros and ignored by a receiver", HFILL }
 469                 },
 470                 { &hf_msdp_sa_sprefix_len,
 471                         { "Sprefix len",           "msdp.sa.sprefix_len",
 472                         FT_UINT8, BASE_DEC, NULL, 0,
 473                         "The route prefix length associated with source address", HFILL }
 474                 },
 475                 { &hf_msdp_sa_group_addr,
 476                         { "Group Address",           "msdp.sa.group_addr",
 477                         FT_IPv4, 0, NULL, 0,
 478                         "The group address the active source has sent data to", HFILL }
 479                 },
 480                 { &hf_msdp_sa_src_addr,
 481                         { "Source Address",           "msdp.sa.src_addr",
 482                         FT_IPv4, 0, NULL, 0,
 483                         "The IP address of the active source", HFILL }
 484                 },
 485                 { &hf_msdp_sa_req_res,
 486                         { "Reserved",           "msdp.sa_req.res",
 487                         FT_UINT8, BASE_HEX, NULL, 0,
 488                         "Transmitted as zeros and ignored by a receiver", HFILL }
 489                 },
 490                 { &hf_msdp_sa_req_group,
 491                         { "Group Address",           "msdp.sa_req.group_addr",
 492                         FT_IPv4, 0, NULL, 0,
 493                         "The group address the MSDP peer is requesting", HFILL }
 494                 },
 495                 { &hf_msdp_not_o,
 496                         { "Open-bit",           "msdp.not.o",
 497                         FT_UINT8, BASE_HEX, NULL, 0x80,
 498                         "If clear, the connection will be closed", HFILL }
 499                 },
 500                 { &hf_msdp_not_error,
 501                         { "Error Code",           "msdp.not.error",
 502                         FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
 503                         "Indicates the type of Notification", HFILL }
 504                 },
 505                 { &hf_msdp_not_error_sub,
 506                         { "Error subode",           "msdp.not.error_sub",
 507                         FT_UINT8, BASE_DEC, NULL, 0,
 508                         "Error subcode", HFILL }
 509                 },
 510                 { &hf_msdp_not_ipv4,
 511                         { "IPv4 address",           "msdp.not.ipv4",
 512                         FT_IPv4, 0, NULL, 0,
 513                         "Group/RP/Source address in Notification messages", HFILL }
 514                 },
 515                 { &hf_msdp_not_res,
 516                         { "Reserved",           "msdp.not.res",
 517                         FT_UINT24, BASE_HEX, NULL, 0,
 518                         "Reserved field in Notification messages", HFILL }
 519                 },
 520                 { &hf_msdp_not_entry_count,
 521                         { "Entry Count",           "msdp.not.entry_count",
 522                         FT_UINT24, BASE_HEX, NULL, 0,
 523                         "Entry Count in Notification messages", HFILL }
 524                 },
 525                 { &hf_msdp_not_sprefix_len,
 526                         { "Sprefix len",           "msdp.not.sprefix_len",
 527                         FT_UINT8, BASE_DEC, NULL, 0,
 528                         "Source prefix length in Notification messages", HFILL }
 529                 },
 530         };
 531
 532         static gint *ett[] = {
 533                 &ett_msdp,
 534                 &ett_msdp_sa_entry,
 535                 &ett_msdp_sa_enc_data,
 536                 &ett_msdp_not_data,
 537         };
 538
 539         proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
 540             "MSDP", "msdp");
 541
 542         proto_register_field_array(proto_msdp, hf, array_length(hf));
 543         proto_register_subtree_array(ett, array_length(ett));
 544 }
 545
 546 void
 547 proto_reg_handoff_msdp(void)
 548 {
 549         dissector_handle_t msdp_handle;
 550
 551         msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
 552         dissector_add("tcp.port", 639, msdp_handle);
 553
 554         ip_handle = find_dissector("ip");
 555
 556         return;
 557 }