packet-rtp.c

   1 /* packet-rtp.c
   2  *
   3  * Routines for RTP dissection
   4  * RTP = Real time Transport Protocol
   5  *
   6  * Copyright 2000, Philips Electronics N.V.
   7  * Written by Andreas Sikkema <andreas.sikkema@philips.com>
   8  *
   9  * $Id: packet-rtp.c,v 1.25 2001/09/08 00:43:51 guy Exp $
  10  *
  11  * Ethereal - Network traffic analyzer
  12  * By Gerald Combs <gerald@ethereal.com>
  13  * Copyright 1998 Gerald Combs
  14  *
  15  * This program is free software; you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License
  17  * as published by the Free Software Foundation; either version 2
  18  * of the License, or (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  28  */
  29
  30 /*
  31  * This dissector tries to dissect the RTP protocol according to Annex A
  32  * of ITU-T Recommendation H.225.0 (02/98) or RFC 1889
  33  *
  34  * RTP traffic is handled by an even UDP portnumber. This can be any
  35  * port number, but there is a registered port available, port 5004
  36  * See Annex B of ITU-T Recommendation H.225.0, section B.7
  37  *
  38  * This doesn't dissect older versions of RTP, such as:
  39  *
  40  *    the vat protocol ("version 0") - see
  41  *
  42  *      ftp://ftp.ee.lbl.gov/conferencing/vat/alpha-test/vatsrc-4.0b2.tar.gz
  43  *
  44  *    and look in "session-vat.cc" if you want to write a dissector
  45  *    (have fun - there aren't any nice header files showing the packet
  46  *    format);
  47  *
  48  *    version 1, as documented in
  49  *
  50  *      ftp://gaia.cs.umass.edu/pub/hgschulz/rtp/draft-ietf-avt-rtp-04.txt
  51  */
  52
  53
  54 #ifdef HAVE_CONFIG_H
  55 # include "config.h"
  56 #endif
  57
  58 #include <glib.h>
  59 #include "packet.h"
  60
  61 #ifdef HAVE_SYS_TYPES_H
  62 #  include <sys/types.h>
  63 #endif
  64
  65 #ifdef HAVE_NETINET_IN_H
  66 #  include <netinet/in.h>
  67 #endif
  68
  69 #include <stdio.h>
  70 #include <string.h>
  71
  72 #include "packet-rtp.h"
  73 #include "conversation.h"
  74
  75 /* RTP header fields             */
  76 static int proto_rtp           = -1;
  77 static int hf_rtp_version      = -1;
  78 static int hf_rtp_padding      = -1;
  79 static int hf_rtp_extension    = -1;
  80 static int hf_rtp_csrc_count   = -1;
  81 static int hf_rtp_marker       = -1;
  82 static int hf_rtp_payload_type = -1;
  83 static int hf_rtp_seq_nr       = -1;
  84 static int hf_rtp_timestamp    = -1;
  85 static int hf_rtp_ssrc         = -1;
  86 static int hf_rtp_csrc_item    = -1;
  87 static int hf_rtp_data         = -1;
  88 static int hf_rtp_padding_data = -1;
  89 static int hf_rtp_padding_count= -1;
  90
  91 /* RTP header extension fields   */
  92 static int hf_rtp_prof_define  = -1;
  93 static int hf_rtp_length       = -1;
  94 static int hf_rtp_hdr_ext      = -1;
  95
  96 /* RTP fields defining a sub tree */
  97 static gint ett_rtp       = -1;
  98 static gint ett_csrc_list = -1;
  99 static gint ett_hdr_ext   = -1;
 100
 101 static dissector_handle_t h261_handle;
 102 static dissector_handle_t mpeg1_handle;
 103
 104 /*
 105  * Fields in the first octet of the RTP header.
 106  */
 107
 108 /* Version is the first 2 bits of the first octet*/
 109 #define RTP_VERSION(octet)      ((octet) >> 6)
 110
 111 /* Padding is the third bit; No need to shift, because true is any value
 112    other than 0! */
 113 #define RTP_PADDING(octet)      ((octet) & 0x20)
 114
 115 /* Extension bit is the fourth bit */
 116 #define RTP_EXTENSION(octet)    ((octet) & 0x10)
 117
 118 /* CSRC count is the last four bits */
 119 #define RTP_CSRC_COUNT(octet)   ((octet) & 0xF)
 120
 121 static const value_string rtp_version_vals[] =
 122 {
 123         { 0, "Old VAT Version" },
 124         { 1, "First Draft Version" },
 125         { 2, "RFC 1889 Version" },
 126         { 0, NULL },
 127 };
 128
 129 /*
 130  * Fields in the second octet of the RTP header.
 131  */
 132
 133 /* Marker is the first bit of the second octet */
 134 #define RTP_MARKER(octet)       ((octet) & 0x80)
 135
 136 /* Payload type is the last 7 bits */
 137 #define RTP_PAYLOAD_TYPE(octet) ((octet) & 0x7F)
 138
 139 /*
 140  * RTP Payload types
 141  * Table B.2 / H.225.0
 142  * Also RFC 1890
 143  */
 144 #define PT_PCMU         0
 145 #define PT_1016         1
 146 #define PT_G721         2
 147 #define PT_GSM          3
 148 #define PT_G723         4
 149 #define PT_DVI4_8000    5
 150 #define PT_DVI4_16000   6
 151 #define PT_LPC          7
 152 #define PT_PCMA         8
 153 #define PT_G722         9
 154 #define PT_L16_STEREO   10
 155 #define PT_L16_MONO     11
 156 #define PT_MPA          14
 157 #define PT_G728         15
 158 #define PT_G729         18
 159 #define PT_CELB         25
 160 #define PT_JPEG         26
 161 #define PT_NV           28
 162 #define PT_H261         31
 163 #define PT_MPV          32
 164 #define PT_MP2T         33
 165 #define PT_H263         34
 166
 167 static const value_string rtp_payload_type_vals[] =
 168 {
 169         { PT_PCMU,      "ITU-T G.711 PCMU" },
 170         { PT_1016,      "USA Federal Standard FS-1016" },
 171         { PT_G721,      "ITU-T G.721" },
 172         { PT_GSM,       "GSM 06.10" },
 173         { PT_G723,      "ITU-T G.723" },
 174         { PT_DVI4_8000, "DVI4 8000 samples/s" },
 175         { PT_DVI4_16000, "DVI4 16000 samples/s" },
 176         { PT_LPC,       "LPC" },
 177         { PT_PCMA,      "ITU-T G.711 PCMA" },
 178         { PT_G722,      "ITU-T G.722" },
 179         { PT_L16_STEREO, "16-bit uncompressed audio, stereo" },
 180         { PT_L16_MONO,  "16-bit uncompressed audio, monaural" },
 181         { PT_MPA,       "MPEG-I/II Audeo"},
 182         { PT_G728,      "ITU-T G.728" },
 183         { PT_G729,      "ITU-T G.729" },
 184         { PT_CELB,      "Sun CELL-B" },
 185         { PT_JPEG,      "JPEG" },
 186         { PT_NV,        "'nv' program" },
 187         { PT_H261,      "ITU-T H.261" },
 188         { PT_MPV,       "MPEG-I/II Video"},
 189         { PT_MP2T,      "MPEG-II transport streams"},
 190         { PT_H263,      "ITU-T H.263" },
 191         { 0,            NULL },
 192 };
 193
 194 static address fake_addr;
 195 static int heur_init = FALSE;
 196
 197 void rtp_add_address( packet_info *pinfo, const unsigned char* ip_addr,
 198     int prt )
 199 {
 200         address src_addr;
 201         conversation_t* pconv;
 202
 203         /*
 204          * If this isn't the first time this packet has been processed,
 205          * we've already done this work, so we don't need to do it
 206          * again.
 207          */
 208         if (pinfo->fd->flags.visited)
 209                 return;
 210
 211         src_addr.type = AT_IPv4;
 212         src_addr.len = 4;
 213         src_addr.data = ip_addr;
 214
 215         /*
 216          * The first time the function is called let the tcp dissector
 217          * know that we're interested in traffic
 218          */
 219         if ( ! heur_init ) {
 220                 heur_dissector_add( "udp", dissect_rtp_heur, proto_rtp );
 221                 heur_init = TRUE;
 222         }
 223
 224         /*
 225          * Check if the ip address an dport combination is not
 226          * already registered
 227          */
 228         pconv = find_conversation( &src_addr, &fake_addr, PT_UDP, prt, 0, 0 );
 229
 230         /*
 231          * If not, add
 232          * XXX - use wildcard address and port B?
 233          */
 234         if ( ! pconv ) {
 235                 pconv = conversation_new( &src_addr, &fake_addr, PT_UDP,
 236                     (guint32) prt, (guint32) 0, 0 );
 237                 conversation_add_proto_data(pconv, proto_rtp, NULL);
 238         }
 239
 240 }
 241
 242 #if 0
 243 static void rtp_init( void )
 244 {
 245         unsigned char* tmp_data;
 246         int i;
 247
 248         /* Create a fake adddress... */
 249         fake_addr.type = AT_IPv4;
 250         fake_addr.len = 4;
 251
 252         tmp_data = malloc( fake_addr.len );
 253         for ( i = 0; i < fake_addr.len; i++) {
 254                 tmp_data[i] = 0;
 255         }
 256         fake_addr.data = tmp_data;
 257 }
 258 #endif
 259
 260 gboolean
 261 dissect_rtp_heur( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
 262 {
 263         conversation_t* pconv;
 264
 265         if (!proto_is_protocol_enabled(proto_rtp))
 266                 return FALSE;   /* RTP has been disabled */
 267
 268         /* This is a heuristic dissector, which means we get all the TCP
 269          * traffic not sent to a known dissector and not claimed by
 270          * a heuristic dissector called before us!
 271          * So we first check if the frame is really meant for us.
 272          */
 273         if ( ( pconv = find_conversation( &pinfo->src, &fake_addr, pinfo->ptype,
 274             pinfo->srcport, 0, 0 ) ) == NULL ) {
 275                 /*
 276                  * The source ip:port combination was not what we were
 277                  * looking for, check the destination
 278                  */
 279                 if ( ( pconv = find_conversation( &pinfo->dst, &fake_addr,
 280                     pinfo->ptype, pinfo->destport, 0, 0 ) ) == NULL ) {
 281                         return FALSE;
 282                 }
 283         }
 284
 285         /*
 286          * An RTP conversation always has a data item for RTP.
 287          * (Its existence is sufficient to indicate that this is an RTP
 288          * conversation.)
 289          */
 290         if (conversation_get_proto_data(pconv, proto_rtp) == NULL)
 291                 return FALSE;
 292
 293         dissect_rtp( tvb, pinfo, tree );
 294
 295         return TRUE;
 296 }
 297
 298 static void
 299 dissect_rtp_data( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 300     proto_tree *rtp_tree, int offset, unsigned int data_len,
 301     unsigned int data_reported_len, unsigned int payload_type )
 302 {
 303         tvbuff_t *newtvb;
 304
 305         switch( payload_type ) {
 306                 case PT_H261:
 307                         newtvb = tvb_new_subset( tvb, offset, data_len,
 308                             data_reported_len );
 309                         call_dissector(h261_handle, newtvb, pinfo, tree);
 310                         break;
 311
 312                 case PT_MPV:
 313                         newtvb = tvb_new_subset( tvb, offset, data_len,
 314                             data_reported_len );
 315                         call_dissector(mpeg1_handle, newtvb, pinfo, tree);
 316                         break;
 317
 318                 default:
 319                         proto_tree_add_item( rtp_tree, hf_rtp_data, tvb, offset, data_len, FALSE );
 320                         break;
 321         }
 322 }
 323
 324 void
 325 dissect_rtp( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
 326 {
 327         proto_item *ti            = NULL;
 328         proto_tree *rtp_tree      = NULL;
 329         proto_tree *rtp_csrc_tree = NULL;
 330         guint8      octet;
 331         unsigned int version;
 332         gboolean    padding_set;
 333         gboolean    extension_set;
 334         unsigned int csrc_count;
 335         gboolean    marker_set;
 336         unsigned int payload_type;
 337         unsigned int i            = 0;
 338         unsigned int hdr_extension= 0;
 339         unsigned int padding_count;
 340         int         data_len;
 341         unsigned int offset = 0;
 342         guint16     seq_num;
 343         guint32     timestamp;
 344         guint32     sync_src;
 345         guint32     csrc_item;
 346
 347         CHECK_DISPLAY_AS_DATA(proto_rtp, tvb, pinfo, tree);
 348
 349         pinfo->current_proto = "RTP";
 350
 351         /* Get the fields in the first octet */
 352         octet = tvb_get_guint8( tvb, offset );
 353         version = RTP_VERSION( octet );
 354
 355         if (version != 2) {
 356                 /*
 357                  * Unknown or unsupported version.
 358                  */
 359                 if ( check_col( pinfo->fd, COL_PROTOCOL ) )   {
 360                         col_set_str( pinfo->fd, COL_PROTOCOL, "RTP" );
 361                 }
 362
 363                 if ( check_col( pinfo->fd, COL_INFO) ) {
 364                         col_add_fstr( pinfo->fd, COL_INFO,
 365                             "Unknown RTP version %u", version);
 366                 }
 367
 368                 if ( tree ) {
 369                         ti = proto_tree_add_item( tree, proto_rtp, tvb, offset, tvb_length_remaining( tvb, offset ), FALSE );
 370                         rtp_tree = proto_item_add_subtree( ti, ett_rtp );
 371
 372                         proto_tree_add_uint( rtp_tree, hf_rtp_version, tvb,
 373                             offset, 1, version );
 374                 }
 375                 return;
 376         }
 377
 378         padding_set = RTP_PADDING( octet );
 379         extension_set = RTP_EXTENSION( octet );
 380         csrc_count = RTP_CSRC_COUNT( octet );
 381
 382         /* Get the fields in the second octet */
 383         octet = tvb_get_guint8( tvb, offset + 1 );
 384         marker_set = RTP_MARKER( octet );
 385         payload_type = RTP_PAYLOAD_TYPE( octet );
 386
 387         /* Get the subsequent fields */
 388         seq_num = tvb_get_ntohs( tvb, offset + 2 );
 389         timestamp = tvb_get_ntohl( tvb, offset + 4 );
 390         sync_src = tvb_get_ntohl( tvb, offset + 8 );
 391
 392         if ( check_col( pinfo->fd, COL_PROTOCOL ) )   {
 393                 col_set_str( pinfo->fd, COL_PROTOCOL, "RTP" );
 394         }
 395
 396         if ( check_col( pinfo->fd, COL_INFO) ) {
 397                 col_add_fstr( pinfo->fd, COL_INFO,
 398                     "Payload type=%s, SSRC=%u, Seq=%u, Time=%u%s",
 399                     val_to_str( payload_type, rtp_payload_type_vals,
 400                         "Unknown (%u)" ),
 401                     sync_src,
 402                     seq_num,
 403                     timestamp,
 404                     marker_set ? ", Mark" : "");
 405         }
 406
 407         if ( tree ) {
 408                 ti = proto_tree_add_item( tree, proto_rtp, tvb, offset, tvb_length_remaining( tvb, offset ), FALSE );
 409                 rtp_tree = proto_item_add_subtree( ti, ett_rtp );
 410
 411                 proto_tree_add_uint( rtp_tree, hf_rtp_version, tvb,
 412                     offset, 1, version );
 413                 proto_tree_add_boolean( rtp_tree, hf_rtp_padding, tvb,
 414                     offset, 1, padding_set );
 415                 proto_tree_add_boolean( rtp_tree, hf_rtp_extension, tvb,
 416                     offset, 1, extension_set );
 417                 proto_tree_add_uint( rtp_tree, hf_rtp_csrc_count, tvb,
 418                     offset, 1, csrc_count );
 419                 offset++;
 420
 421                 proto_tree_add_boolean( rtp_tree, hf_rtp_marker, tvb, offset,
 422                     1, marker_set );
 423                 proto_tree_add_uint( rtp_tree, hf_rtp_payload_type, tvb,
 424                     offset, 1, payload_type );
 425                 offset++;
 426
 427                 /* Sequence number 16 bits (2 octets) */
 428                 proto_tree_add_uint( rtp_tree, hf_rtp_seq_nr, tvb, offset, 2, seq_num );
 429                 offset += 2;
 430
 431                 /* Timestamp 32 bits (4 octets) */
 432                 proto_tree_add_uint( rtp_tree, hf_rtp_timestamp, tvb, offset, 4, timestamp );
 433                 offset += 4;
 434
 435                 /* Synchronization source identifier 32 bits (4 octets) */
 436                 proto_tree_add_uint( rtp_tree, hf_rtp_ssrc, tvb, offset, 4, sync_src );
 437                 offset += 4;
 438
 439                 /* CSRC list*/
 440                 if ( csrc_count > 0 ) {
 441                         ti = proto_tree_add_text(rtp_tree, tvb, offset, csrc_count * 4, "Contributing Source identifiers");
 442                         rtp_csrc_tree = proto_item_add_subtree( ti, ett_csrc_list );
 443                         for (i = 0; i < csrc_count; i++ ) {
 444                                 csrc_item = tvb_get_ntohl( tvb, offset );
 445                                 proto_tree_add_uint_format( rtp_csrc_tree,
 446                                     hf_rtp_csrc_item, tvb, offset, 4,
 447                                     csrc_item,
 448                                     "CSRC item %d: %u",
 449                                     i, csrc_item );
 450                                 offset += 4;
 451                         }
 452                 }
 453
 454                 /* Optional RTP header extension */
 455                 if ( extension_set ) {
 456                         /* Defined by profile field is 16 bits (2 octets) */
 457                         proto_tree_add_uint( rtp_tree, hf_rtp_prof_define, tvb, offset, 2, tvb_get_ntohs( tvb, offset ) );
 458                         offset += 2;
 459
 460                         hdr_extension = tvb_get_ntohs( tvb, offset );
 461                         proto_tree_add_uint( rtp_tree, hf_rtp_length, tvb,
 462                             offset, 2, hdr_extension);
 463                         offset += 2;
 464                         if ( hdr_extension > 0 ) {
 465                                 ti = proto_tree_add_text(rtp_tree, tvb, offset, csrc_count * 4, "Header extensions");
 466                                 /* I'm re-using the old tree variable here
 467                                    from the CSRC list!*/
 468                                 rtp_csrc_tree = proto_item_add_subtree( ti,
 469                                     ett_hdr_ext );
 470                                 for (i = 0; i < hdr_extension; i++ ) {
 471                                         proto_tree_add_uint( rtp_csrc_tree, hf_rtp_hdr_ext, tvb, offset, 4, tvb_get_ntohl( tvb, offset ) );
 472                                         offset += 4;
 473                                 }
 474                         }
 475                 }
 476
 477                 if ( padding_set ) {
 478                         /*
 479                          * This RTP frame has padding - find it.
 480                          *
 481                          * The padding count is found in the LAST octet of
 482                          * the packet; it contains the number of octets
 483                          * that can be ignored at the end of the packet.
 484                          */
 485                         if (tvb_length(tvb) < tvb_reported_length(tvb)) {
 486                                 /*
 487                                  * We don't *have* the last octet of the
 488                                  * packet, so we can't get the padding
 489                                  * count.
 490                                  *
 491                                  * Put an indication of that into the
 492                                  * tree, and just put in a raw data
 493                                  * item.
 494                                  */
 495                                 proto_tree_add_text(rtp_tree, tvb, 0, 0,
 496                                     "Frame has padding, but not all the frame data was captured");
 497                                 dissect_data(tvb, offset, pinfo, rtp_tree);
 498                                 return;
 499                         }
 500
 501                         padding_count = tvb_get_guint8( tvb,
 502                             tvb_reported_length( tvb ) - 1 );
 503                         data_len =
 504                             tvb_reported_length_remaining( tvb, offset ) - padding_count;
 505                         if (data_len > 0) {
 506                                 /*
 507                                  * There's data left over when you take out
 508                                  * the padding; dissect it.
 509                                  */
 510                                 dissect_rtp_data( tvb, pinfo, tree, rtp_tree,
 511                                     offset,
 512                                     data_len,
 513                                     data_len,
 514                                     payload_type );
 515                                 offset += data_len;
 516                         } else if (data_len < 0) {
 517                                 /*
 518                                  * The padding count is bigger than the
 519                                  * amount of RTP payload in the packet!
 520                                  * Clip the padding count.
 521                                  *
 522                                  * XXX - put an item in the tree to indicate
 523                                  * that the padding count is bogus?
 524                                  */
 525                                 padding_count =
 526                                     tvb_reported_length_remaining(tvb, offset);
 527                         }
 528                         if (padding_count > 1) {
 529                                 /*
 530                                  * There's more than one byte of padding;
 531                                  * show all but the last byte as padding
 532                                  * data.
 533                                  */
 534                                 proto_tree_add_item( rtp_tree, hf_rtp_padding_data,
 535                                     tvb, offset, padding_count - 1, FALSE );
 536                                 offset += padding_count - 1;
 537                         }
 538                         /*
 539                          * Show the last byte in the PDU as the padding
 540                          * count.
 541                          */
 542                         proto_tree_add_item( rtp_tree, hf_rtp_padding_count,
 543                             tvb, offset, 1, FALSE );
 544                 }
 545                 else {
 546                         /*
 547                          * No padding.
 548                          */
 549                         dissect_rtp_data( tvb, pinfo, tree, rtp_tree, offset,
 550                             tvb_length_remaining( tvb, offset ),
 551                             tvb_reported_length_remaining( tvb, offset ),
 552                             payload_type );
 553                 }
 554         }
 555 }
 556
 557 void
 558 proto_register_rtp(void)
 559 {
 560         static hf_register_info hf[] =
 561         {
 562                 {
 563                         &hf_rtp_version,
 564                         {
 565                                 "Version",
 566                                 "rtp.version",
 567                                 FT_UINT8,
 568                                 BASE_DEC,
 569                                 VALS(rtp_version_vals),
 570                                 0x0,
 571                                 "", HFILL
 572                         }
 573                 },
 574                 {
 575                         &hf_rtp_padding,
 576                         {
 577                                 "Padding",
 578                                 "rtp.padding",
 579                                 FT_BOOLEAN,
 580                                 BASE_NONE,
 581                                 NULL,
 582                                 0x0,
 583                                 "", HFILL
 584                         }
 585                 },
 586                 {
 587                         &hf_rtp_extension,
 588                         {
 589                                 "Extension",
 590                                 "rtp.ext",
 591                                 FT_BOOLEAN,
 592                                 BASE_NONE,
 593                                 NULL,
 594                                 0x0,
 595                                 "", HFILL
 596                         }
 597                 },
 598                 {
 599                         &hf_rtp_csrc_count,
 600                         {
 601                                 "Contributing source identifiers count",
 602                                 "rtp.cc",
 603                                 FT_UINT8,
 604                                 BASE_DEC,
 605                                 NULL,
 606                                 0x0,
 607                                 "", HFILL
 608                         }
 609                 },
 610                 {
 611                         &hf_rtp_marker,
 612                         {
 613                                 "Marker",
 614                                 "rtp.marker",
 615                                 FT_BOOLEAN,
 616                                 BASE_NONE,
 617                                 NULL,
 618                                 0x0,
 619                                 "", HFILL
 620                         }
 621                 },
 622                 {
 623                         &hf_rtp_payload_type,
 624                         {
 625                                 "Payload type",
 626                                 "rtp.p_type",
 627                                 FT_UINT8,
 628                                 BASE_DEC,
 629                                 VALS(rtp_payload_type_vals),
 630                                 0x0,
 631                                 "", HFILL
 632                         }
 633                 },
 634                 {
 635                         &hf_rtp_seq_nr,
 636                         {
 637                                 "Sequence number",
 638                                 "rtp.seq",
 639                                 FT_UINT16,
 640                                 BASE_DEC,
 641                                 NULL,
 642                                 0x0,
 643                                 "", HFILL
 644                         }
 645                 },
 646                 {
 647                         &hf_rtp_timestamp,
 648                         {
 649                                 "Timestamp",
 650                                 "rtp.timestamp",
 651                                 FT_UINT32,
 652                                 BASE_DEC,
 653                                 NULL,
 654                                 0x0,
 655                                 "", HFILL
 656                         }
 657                 },
 658                 {
 659                         &hf_rtp_ssrc,
 660                         {
 661                                 "Synchronization Source identifier",
 662                                 "rtp.ssrc",
 663                                 FT_UINT32,
 664                                 BASE_DEC,
 665                                 NULL,
 666                                 0x0,
 667                                 "", HFILL
 668                         }
 669                 },
 670                 {
 671                         &hf_rtp_prof_define,
 672                         {
 673                                 "Defined by profile",
 674                                 "rtp.ext.profile",
 675                                 FT_UINT16,
 676                                 BASE_DEC,
 677                                 NULL,
 678                                 0x0,
 679                                 "", HFILL
 680                         }
 681                 },
 682                 {
 683                         &hf_rtp_length,
 684                         {
 685                                 "Extension length",
 686                                 "rtp.ext.len",
 687                                 FT_UINT16,
 688                                 BASE_DEC,
 689                                 NULL,
 690                                 0x0,
 691                                 "", HFILL
 692                         }
 693                 },
 694                 {
 695                         &hf_rtp_csrc_item,
 696                         {
 697                                 "CSRC item",
 698                                 "rtp.csrc.item",
 699                                 FT_UINT32,
 700                                 BASE_DEC,
 701                                 NULL,
 702                                 0x0,
 703                                 "", HFILL
 704                         }
 705                 },
 706                 {
 707                         &hf_rtp_hdr_ext,
 708                         {
 709                                 "Header extension",
 710                                 "rtp.hdr_ext",
 711                                 FT_UINT32,
 712                                 BASE_DEC,
 713                                 NULL,
 714                                 0x0,
 715                                 "", HFILL
 716                         }
 717                 },
 718                 {
 719                         &hf_rtp_data,
 720                         {
 721                                 "Payload",
 722                                 "rtp.payload",
 723                                 FT_BYTES,
 724                                 BASE_HEX,
 725                                 NULL,
 726                                 0x0,
 727                                 "", HFILL
 728                         }
 729                 },
 730                 {
 731                         &hf_rtp_padding_data,
 732                         {
 733                                 "Padding data",
 734                                 "rtp.padding.data",
 735                                 FT_BYTES,
 736                                 BASE_HEX,
 737                                 NULL,
 738                                 0x0,
 739                                 "", HFILL
 740                         }
 741                 },
 742                 {
 743                         &hf_rtp_padding_count,
 744                         {
 745                                 "Padding count",
 746                                 "rtp.padding.count",
 747                                 FT_UINT8,
 748                                 BASE_DEC,
 749                                 NULL,
 750                                 0x0,
 751                                 "", HFILL
 752                         }
 753                 },
 754 };
 755
 756         static gint *ett[] =
 757         {
 758                 &ett_rtp,
 759                 &ett_csrc_list,
 760                 &ett_hdr_ext,
 761         };
 762
 763
 764         proto_rtp = proto_register_protocol("Real-Time Transport Protocol",
 765             "RTP", "rtp");
 766         proto_register_field_array(proto_rtp, hf, array_length(hf));
 767         proto_register_subtree_array(ett, array_length(ett));
 768
 769         register_dissector("rtp", dissect_rtp, proto_rtp);
 770
 771 #if 0
 772         register_init_routine( &rtp_init );
 773 #endif
 774 }
 775
 776 void
 777 proto_reg_handoff_rtp(void)
 778 {
 779         /*
 780          * Get handles for the H.261 and MPEG-1 dissectors.
 781          */
 782         h261_handle = find_dissector("h261");
 783         mpeg1_handle = find_dissector("mpeg1");
 784
 785         /*
 786          * Register this dissector as one that can be assigned to a
 787          * UDP conversation.
 788          */
 789         conv_dissector_add("udp", dissect_rtp, proto_rtp);
 790 }