asn1/t38/packet-t38-template.c

   1 /* packet-t38.c
   2  * Routines for T.38 packet dissection
   3  * 2003  Hans Viens
   4  * 2004  Alejandro Vaquero, add support Conversations for SDP
   5  * 2006  Alejandro Vaquero, add T30 reassemble and dissection
   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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  26  */
  27
  28
  29 /* Depending on what ASN.1 specification is used you may have to change
  30  * the preference setting regarding Pre-Corrigendum ASN.1 specification:
  31  * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/1998/T38.html  (Pre-Corrigendum=TRUE)
  32  * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2003/T38(1998).html (Pre-Corrigendum=TRUE)
  33  *
  34  * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2003/T38(2002).html (Pre-Corrigendum=FALSE)
  35  * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2002/t38.html  (Pre-Corrigendum=FALSE)
  36  * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2002-Amd1/T38.html (Pre-Corrigendum=FALSE)
  37  */
  38
  39 /* TO DO:
  40  * - TCP desegmentation is currently not supported for T.38 IFP directly over TCP.
  41  * - H.245 dissectors should be updated to start conversations for T.38 similar to RTP.
  42  * - Sometimes the last octet is not high-lighted when selecting something in the tree. Bug in PER dissector?
  43  * - Add support for RTP payload audio/t38 (draft-jones-avt-audio-t38-03.txt), i.e. T38 in RTP packets.
  44  */
  45
  46
  47 #ifdef HAVE_CONFIG_H
  48 # include "config.h"
  49 #endif
  50
  51 #include <glib.h>
  52 #include <epan/packet.h>
  53 #include <epan/reassemble.h>
  54 #include <epan/conversation.h>
  55 #include <epan/tap.h>
  56 #include <epan/expert.h>
  57
  58 #include <string.h>
  59
  60 #include "packet-t38.h"
  61 #include <epan/prefs.h>
  62 #include <epan/ipproto.h>
  63 #include <epan/asn1.h>
  64 #include "packet-per.h"
  65 #include "packet-tpkt.h"
  66 #include <epan/emem.h>
  67 #include <epan/strutil.h>
  68
  69 #define PORT_T38 6004
  70 static guint global_t38_tcp_port = PORT_T38;
  71 static guint global_t38_udp_port = PORT_T38;
  72
  73 static int t38_tap = -1;
  74
  75 /* dissect using the Pre Corrigendum T.38 ASN.1 specification (1998) */
  76 static gboolean use_pre_corrigendum_asn1_specification = TRUE;
  77
  78 /* dissect packets that looks like RTP version 2 packets as RTP     */
  79 /* instead of as T.38. This may result in that some T.38 UPTL       */
  80 /* packets with sequence number values higher than 32767 may be     */
  81 /* shown as RTP packets.                                            */
  82 static gboolean dissect_possible_rtpv2_packets_as_rtp = FALSE;
  83
  84
  85 /* Reassembly of T.38 PDUs over TPKT over TCP */
  86 static gboolean t38_tpkt_reassembly = TRUE;
  87
  88 /* Preference setting whether TPKT header is used when sending T.38 over TCP.
  89  * The default setting is Maybe where the dissector will look on the first
  90  * bytes to try to determine whether TPKT header is used or not. This may not
  91  * work so well in some cases. You may want to change the setting to Always or
  92  * Newer.
  93  */
  94 #define T38_TPKT_NEVER 0   /* Assume that there is never a TPKT header    */
  95 #define T38_TPKT_ALWAYS 1  /* Assume that there is always a TPKT header   */
  96 #define T38_TPKT_MAYBE 2   /* Assume TPKT if first octets are 03-00-xx-xx */
  97 static gint t38_tpkt_usage = T38_TPKT_MAYBE;
  98
  99 static const enum_val_t t38_tpkt_options[] = {
 100   {"never", "Never", T38_TPKT_NEVER},
 101   {"always", "Always", T38_TPKT_ALWAYS},
 102   {"maybe", "Maybe", T38_TPKT_MAYBE},
 103   {NULL, NULL, -1}
 104 };
 105
 106
 107
 108 /* T38 */
 109 static dissector_handle_t t38_udp_handle;
 110 static dissector_handle_t t38_tcp_handle;
 111 static dissector_handle_t t38_tcp_pdu_handle;
 112 static dissector_handle_t rtp_handle;
 113 static dissector_handle_t t30_hdlc_handle;
 114 static dissector_handle_t data_handle;
 115
 116 static gint32 Type_of_msg_value;
 117 static guint32 Data_Field_field_type_value;
 118 static guint32 Data_value;
 119 static guint32 T30ind_value;
 120 static guint32 Data_Field_item_num;
 121
 122 static int proto_t38 = -1;
 123 #include "packet-t38-hf.c"
 124
 125 /* T38 setup fields */
 126 static int hf_t38_setup        = -1;
 127 static int hf_t38_setup_frame  = -1;
 128 static int hf_t38_setup_method = -1;
 129
 130 /* T38 Data reassemble fields */
 131 static int hf_t38_fragments = -1;
 132 static int hf_t38_fragment = -1;
 133 static int hf_t38_fragment_overlap = -1;
 134 static int hf_t38_fragment_overlap_conflicts = -1;
 135 static int hf_t38_fragment_multiple_tails = -1;
 136 static int hf_t38_fragment_too_long_fragment = -1;
 137 static int hf_t38_fragment_error = -1;
 138 static int hf_t38_reassembled_in = -1;
 139 static int hf_t38_reassembled_length = -1;
 140
 141 static gint ett_t38 = -1;
 142 #include "packet-t38-ett.c"
 143 static gint ett_t38_setup = -1;
 144
 145 static gint ett_data_fragment = -1;
 146 static gint ett_data_fragments = -1;
 147
 148 static gboolean primary_part = TRUE;
 149 static guint32 seq_number = 0;
 150
 151 /* Tables for reassembly of Data fragments. */
 152 static GHashTable *data_fragment_table = NULL;
 153
 154 static const fragment_items data_frag_items = {
 155         /* Fragment subtrees */
 156         &ett_data_fragment,
 157         &ett_data_fragments,
 158         /* Fragment fields */
 159         &hf_t38_fragments,
 160         &hf_t38_fragment,
 161         &hf_t38_fragment_overlap,
 162         &hf_t38_fragment_overlap_conflicts,
 163         &hf_t38_fragment_multiple_tails,
 164         &hf_t38_fragment_too_long_fragment,
 165         &hf_t38_fragment_error,
 166         /* Reassembled in field */
 167         &hf_t38_reassembled_in,
 168         /* Reassembled length field */
 169         &hf_t38_reassembled_length,
 170         /* Tag */
 171         "Data fragments"
 172 };
 173
 174 typedef struct _fragment_key {
 175         address src;
 176         address dst;
 177         guint32 id;
 178 } fragment_key;
 179
 180 static conversation_t *p_conv= NULL;
 181 static t38_conv *p_t38_conv = NULL;
 182 static t38_conv *p_t38_packet_conv = NULL;
 183 static t38_conv_info *p_t38_conv_info = NULL;
 184 static t38_conv_info *p_t38_packet_conv_info = NULL;
 185
 186 /* RTP Version is the first 2 bits of the first octet in the UDP payload*/
 187 #define RTP_VERSION(octet)      ((octet) >> 6)
 188
 189 void proto_reg_handoff_t38(void);
 190
 191 static void show_setup_info(tvbuff_t *tvb, proto_tree *tree, t38_conv *p_t38_conv);
 192 /* Preferences bool to control whether or not setup info should be shown */
 193 static gboolean global_t38_show_setup_info = TRUE;
 194
 195 /* Can tap up to 4 T38 packets within same packet */
 196 /* We only tap the primary part, not the redundancy */
 197 #define MAX_T38_MESSAGES_IN_PACKET 4
 198 static t38_packet_info t38_info_arr[MAX_T38_MESSAGES_IN_PACKET];
 199 static int t38_info_current=0;
 200 static t38_packet_info *t38_info=NULL;
 201
 202 static void t38_defragment_init(void)
 203 {
 204         /* Init reassemble tables */
 205         fragment_table_init(&data_fragment_table);
 206 }
 207
 208
 209 /* Set up an T38 conversation */
 210 void t38_add_address(packet_info *pinfo,
 211                      address *addr, int port,
 212                      int other_port,
 213                      const gchar *setup_method, guint32 setup_frame_number)
 214 {
 215         address null_addr;
 216         conversation_t* p_conversation;
 217         t38_conv* p_conversation_data = NULL;
 218
 219         /*
 220          * If this isn't the first time this packet has been processed,
 221          * we've already done this work, so we don't need to do it
 222          * again.
 223          */
 224         if (pinfo->fd->flags.visited)
 225         {
 226                 return;
 227         }
 228
 229         SET_ADDRESS(&null_addr, AT_NONE, 0, NULL);
 230
 231         /*
 232          * Check if the ip address and port combination is not
 233          * already registered as a conversation.
 234          */
 235         p_conversation = find_conversation( setup_frame_number, addr, &null_addr, PT_UDP, port, other_port,
 236                                 NO_ADDR_B | (!other_port ? NO_PORT_B : 0));
 237
 238         /*
 239          * If not, create a new conversation.
 240          */
 241         if ( !p_conversation || p_conversation->setup_frame != setup_frame_number) {
 242                 p_conversation = conversation_new( setup_frame_number, addr, &null_addr, PT_UDP,
 243                                            (guint32)port, (guint32)other_port,
 244                                                                    NO_ADDR2 | (!other_port ? NO_PORT2 : 0));
 245         }
 246
 247         /* Set dissector */
 248         conversation_set_dissector(p_conversation, t38_udp_handle);
 249
 250         /*
 251          * Check if the conversation has data associated with it.
 252          */
 253         p_conversation_data = conversation_get_proto_data(p_conversation, proto_t38);
 254
 255         /*
 256          * If not, add a new data item.
 257          */
 258         if ( ! p_conversation_data ) {
 259                 /* Create conversation data */
 260                 p_conversation_data = se_alloc(sizeof(t38_conv));
 261
 262                 conversation_add_proto_data(p_conversation, proto_t38, p_conversation_data);
 263         }
 264
 265         /*
 266          * Update the conversation data.
 267          */
 268         g_strlcpy(p_conversation_data->setup_method, setup_method, MAX_T38_SETUP_METHOD_SIZE);
 269         p_conversation_data->setup_frame_number = setup_frame_number;
 270                 p_conversation_data->src_t38_info.reass_ID = 0;
 271                 p_conversation_data->src_t38_info.reass_start_seqnum = -1;
 272                 p_conversation_data->src_t38_info.reass_data_type = 0;
 273                 p_conversation_data->src_t38_info.last_seqnum = -1;
 274                 p_conversation_data->src_t38_info.packet_lost = 0;
 275                 p_conversation_data->src_t38_info.burst_lost = 0;
 276                 p_conversation_data->src_t38_info.time_first_t4_data = 0;
 277
 278
 279                 p_conversation_data->dst_t38_info.reass_ID = 0;
 280                 p_conversation_data->dst_t38_info.reass_start_seqnum = -1;
 281                 p_conversation_data->dst_t38_info.reass_data_type = 0;
 282                 p_conversation_data->dst_t38_info.last_seqnum = -1;
 283                 p_conversation_data->dst_t38_info.packet_lost = 0;
 284                 p_conversation_data->dst_t38_info.burst_lost = 0;
 285                 p_conversation_data->dst_t38_info.time_first_t4_data = 0;
 286 }
 287
 288
 289 fragment_data *
 290 force_reassemble_seq(packet_info *pinfo, guint32 id,
 291              GHashTable *fragment_table)
 292 {
 293         fragment_key key;
 294         fragment_data *fd_head;
 295         fragment_data *fd_i;
 296         fragment_data *last_fd;
 297         guint32 dfpos, size, packet_lost, burst_lost, seq_num;
 298
 299         /* create key to search hash with */
 300         key.src = pinfo->src;
 301         key.dst = pinfo->dst;
 302         key.id  = id;
 303
 304         fd_head = g_hash_table_lookup(fragment_table, &key);
 305
 306         /* have we already seen this frame ?*/
 307         if (pinfo->fd->flags.visited) {
 308                 if (fd_head != NULL && fd_head->flags & FD_DEFRAGMENTED) {
 309                         return fd_head;
 310                 } else {
 311                         return NULL;
 312                 }
 313         }
 314
 315         if (fd_head==NULL){
 316                 /* we must have it to continue */
 317                 return NULL;
 318         }
 319
 320         /* check for packet lost and count the burst of packet lost */
 321         packet_lost = 0;
 322         burst_lost = 0;
 323         seq_num = 0;
 324         for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
 325                 if (seq_num != fd_i->offset) {
 326                         packet_lost += fd_i->offset - seq_num;
 327                         if ( (fd_i->offset - seq_num) > burst_lost ) {
 328                                 burst_lost = fd_i->offset - seq_num;
 329                         }
 330                 }
 331                 seq_num = fd_i->offset + 1;
 332         }
 333
 334         /* we have received an entire packet, defragment it and
 335      * free all fragments
 336      */
 337         size=0;
 338         last_fd=NULL;
 339         for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
 340           if(!last_fd || last_fd->offset!=fd_i->offset){
 341             size+=fd_i->len;
 342           }
 343           last_fd=fd_i;
 344         }
 345         fd_head->data = g_malloc(size);
 346         fd_head->len = size;            /* record size for caller       */
 347
 348         /* add all data fragments */
 349         dfpos = 0;
 350         last_fd=NULL;
 351         for (fd_i=fd_head->next;fd_i && fd_i->len + dfpos <= size;fd_i=fd_i->next) {
 352           if (fd_i->len) {
 353             if(!last_fd || last_fd->offset!=fd_i->offset){
 354               memcpy(fd_head->data+dfpos,fd_i->data,fd_i->len);
 355               dfpos += fd_i->len;
 356             } else {
 357               /* duplicate/retransmission/overlap */
 358               fd_i->flags    |= FD_OVERLAP;
 359               fd_head->flags |= FD_OVERLAP;
 360               if( (last_fd->len!=fd_i->datalen)
 361                   || memcmp(last_fd->data, fd_i->data, last_fd->len) ){
 362                         fd_i->flags    |= FD_OVERLAPCONFLICT;
 363                         fd_head->flags |= FD_OVERLAPCONFLICT;
 364               }
 365             }
 366           }
 367           last_fd=fd_i;
 368         }
 369
 370         /* we have defragmented the pdu, now free all fragments*/
 371         for (fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
 372           if(fd_i->data){
 373             g_free(fd_i->data);
 374             fd_i->data=NULL;
 375           }
 376         }
 377
 378         /* mark this packet as defragmented */
 379         fd_head->flags |= FD_DEFRAGMENTED;
 380         fd_head->reassembled_in=pinfo->fd->num;
 381
 382         if (check_col(pinfo->cinfo, COL_INFO))
 383                         col_append_fstr(pinfo->cinfo, COL_INFO, " (t4-data Reassembled: %d pack lost, %d pack burst lost)", packet_lost, burst_lost);
 384
 385         p_t38_packet_conv_info->packet_lost = packet_lost;
 386         p_t38_packet_conv_info->burst_lost = burst_lost;
 387
 388         return fd_head;
 389 }
 390
 391 /* T38 Routines */
 392 #include "packet-t38-fn.c"
 393
 394 /* initialize the tap t38_info and the conversation */
 395 static void
 396 init_t38_info_conv(packet_info *pinfo)
 397 {
 398         /* tap info */
 399         t38_info_current++;
 400         if (t38_info_current==MAX_T38_MESSAGES_IN_PACKET) {
 401                 t38_info_current=0;
 402         }
 403         t38_info = &t38_info_arr[t38_info_current];
 404
 405         t38_info->seq_num = 0;
 406         t38_info->type_msg = 0;
 407         t38_info->data_value = 0;
 408         t38_info->t30ind_value =0;
 409         t38_info->setup_frame_number = 0;
 410         t38_info->Data_Field_field_type_value = 0;
 411         t38_info->desc[0] = '\0';
 412         t38_info->desc_comment[0] = '\0';
 413         t38_info->time_first_t4_data = 0;
 414         t38_info->frame_num_first_t4_data = 0;
 415
 416
 417         /*
 418                 p_t38_packet_conv hold the conversation info in each of the packets.
 419                 p_t38_conv hold the conversation info used to reassemble the HDLC packets, and also the Setup info (e.g SDP)
 420                 If we already have p_t38_packet_conv in the packet, it means we already reassembled the HDLC packets, so we don't
 421                 need to use p_t38_conv
 422         */
 423         p_t38_packet_conv = NULL;
 424         p_t38_conv = NULL;
 425
 426         /* Use existing packet info if available */
 427          p_t38_packet_conv = p_get_proto_data(pinfo->fd, proto_t38);
 428
 429
 430         /* find the conversation used for Reassemble and Setup Info */
 431         p_conv = find_conversation(pinfo->fd->num, &pinfo->net_dst, &pinfo->net_src,
 432                                    pinfo->ptype,
 433                                    pinfo->destport, pinfo->srcport, NO_ADDR_B | NO_PORT_B);
 434
 435         /* create a conv if it doen't exist */
 436         if (!p_conv) {
 437                 p_conv = conversation_new(pinfo->fd->num, &pinfo->net_src, &pinfo->net_dst,
 438                               pinfo->ptype, pinfo->srcport, pinfo->destport, NO_ADDR_B | NO_PORT_B);
 439
 440                 /* Set dissector */
 441                 conversation_set_dissector(p_conv, t38_udp_handle);
 442         }
 443
 444         if (!p_t38_packet_conv) {
 445                 p_t38_conv = conversation_get_proto_data(p_conv, proto_t38);
 446
 447                 /* create the conversation if it doen't exist */
 448                 if (!p_t38_conv) {
 449                         p_t38_conv = se_alloc(sizeof(t38_conv));
 450                         p_t38_conv->setup_method[0] = '\0';
 451                         p_t38_conv->setup_frame_number = 0;
 452
 453                         p_t38_conv->src_t38_info.reass_ID = 0;
 454                         p_t38_conv->src_t38_info.reass_start_seqnum = -1;
 455                         p_t38_conv->src_t38_info.reass_data_type = 0;
 456                         p_t38_conv->src_t38_info.last_seqnum = -1;
 457                         p_t38_conv->src_t38_info.packet_lost = 0;
 458                         p_t38_conv->src_t38_info.burst_lost = 0;
 459                         p_t38_conv->src_t38_info.time_first_t4_data = 0;
 460
 461                         p_t38_conv->dst_t38_info.reass_ID = 0;
 462                         p_t38_conv->dst_t38_info.reass_start_seqnum = -1;
 463                         p_t38_conv->dst_t38_info.reass_data_type = 0;
 464                         p_t38_conv->dst_t38_info.last_seqnum = -1;
 465                         p_t38_conv->dst_t38_info.packet_lost = 0;
 466                         p_t38_conv->dst_t38_info.burst_lost = 0;
 467                         p_t38_conv->dst_t38_info.time_first_t4_data = 0;
 468
 469                         conversation_add_proto_data(p_conv, proto_t38, p_t38_conv);
 470                 }
 471
 472                 /* copy the t38 conversation info to the packet t38 conversation */
 473                 p_t38_packet_conv = se_alloc(sizeof(t38_conv));
 474                 g_strlcpy(p_t38_packet_conv->setup_method, p_t38_conv->setup_method, MAX_T38_SETUP_METHOD_SIZE);
 475                 p_t38_packet_conv->setup_frame_number = p_t38_conv->setup_frame_number;
 476
 477                 memcpy(&(p_t38_packet_conv->src_t38_info), &(p_t38_conv->src_t38_info), sizeof(t38_conv_info));
 478                 memcpy(&(p_t38_packet_conv->dst_t38_info), &(p_t38_conv->dst_t38_info), sizeof(t38_conv_info));
 479
 480                 p_add_proto_data(pinfo->fd, proto_t38, p_t38_packet_conv);
 481         }
 482
 483         if (ADDRESSES_EQUAL(&p_conv->key_ptr->addr1, &pinfo->net_src)) {
 484                 p_t38_conv_info = &(p_t38_conv->src_t38_info);
 485                 p_t38_packet_conv_info = &(p_t38_packet_conv->src_t38_info);
 486         } else {
 487                 p_t38_conv_info = &(p_t38_conv->dst_t38_info);
 488                 p_t38_packet_conv_info = &(p_t38_packet_conv->dst_t38_info);
 489         }
 490
 491         /* update t38_info */
 492         t38_info->setup_frame_number = p_t38_packet_conv->setup_frame_number;
 493 }
 494
 495 /* Entry point for dissection */
 496 static void
 497 dissect_t38_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 498 {
 499         guint8 octet1;
 500         proto_item *it;
 501         proto_tree *tr;
 502         guint32 offset=0;
 503
 504         /*
 505          * XXX - heuristic to check for misidentified packets.
 506          */
 507         if (dissect_possible_rtpv2_packets_as_rtp){
 508                 octet1 = tvb_get_guint8(tvb, offset);
 509                 if (RTP_VERSION(octet1) == 2){
 510                         call_dissector(rtp_handle,tvb,pinfo,tree);
 511                         return;
 512                 }
 513         }
 514
 515         col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.38");
 516         col_clear(pinfo->cinfo, COL_INFO);
 517
 518         primary_part = TRUE;
 519
 520         /* This indicate the item number in the primary part of the T38 message, it is used for the reassemble of T30 packets */
 521         Data_Field_item_num = 0;
 522
 523         it=proto_tree_add_protocol_format(tree, proto_t38, tvb, 0, -1, "ITU-T Recommendation T.38");
 524         tr=proto_item_add_subtree(it, ett_t38);
 525
 526         /* init tap and conv info */
 527         init_t38_info_conv(pinfo);
 528
 529         /* Show Conversation setup info if exists*/
 530         if (global_t38_show_setup_info) {
 531                 show_setup_info(tvb, tr, p_t38_packet_conv);
 532         }
 533
 534         col_append_str(pinfo->cinfo, COL_INFO, "UDP: UDPTLPacket ");
 535
 536         offset = dissect_UDPTLPacket_PDU(tvb, pinfo, tr);
 537
 538         if (tvb_length_remaining(tvb,offset)>0){
 539                 if (tr){
 540                         proto_tree_add_text(tr, tvb, offset, tvb_reported_length_remaining(tvb, offset),
 541                                 "[MALFORMED PACKET or wrong preference settings]");
 542                 }
 543                 col_append_str(pinfo->cinfo, COL_INFO, " [Malformed?]");
 544         }
 545 }
 546
 547 static void
 548 dissect_t38_tcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 549 {
 550         proto_item *it;
 551         proto_tree *tr;
 552         guint32 offset=0;
 553     tvbuff_t *next_tvb;
 554         guint16 ifp_packet_number=1;
 555
 556         col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.38");
 557         col_clear(pinfo->cinfo, COL_INFO);
 558
 559         primary_part = TRUE;
 560
 561         /* This indicate the item number in the primary part of the T38 message, it is used for the reassemble of T30 packets */
 562         Data_Field_item_num = 0;
 563
 564         it=proto_tree_add_protocol_format(tree, proto_t38, tvb, 0, -1, "ITU-T Recommendation T.38");
 565         tr=proto_item_add_subtree(it, ett_t38);
 566
 567         /* init tap and conv info */
 568         init_t38_info_conv(pinfo);
 569
 570         /* Show Conversation setup info if exists*/
 571         if (global_t38_show_setup_info) {
 572                 show_setup_info(tvb, tr, p_t38_packet_conv);
 573         }
 574
 575         col_append_str(pinfo->cinfo, COL_INFO, "TCP: IFPPacket");
 576
 577         while(tvb_length_remaining(tvb,offset)>0)
 578         {
 579                 next_tvb = tvb_new_subset_remaining(tvb, offset);
 580                 offset += dissect_IFPPacket_PDU(next_tvb, pinfo, tr);
 581                 ifp_packet_number++;
 582
 583                 if(tvb_length_remaining(tvb,offset)>0){
 584                         if(t38_tpkt_usage == T38_TPKT_ALWAYS){
 585                                 if(tr){
 586                                         proto_tree_add_text(tr, tvb, offset, tvb_reported_length_remaining(tvb, offset),
 587                                                 "[MALFORMED PACKET or wrong preference settings]");
 588                                 }
 589                                 col_append_str(pinfo->cinfo, COL_INFO, " [Malformed?]");
 590                                 break;
 591                         }
 592                         else {
 593                                 if (check_col(pinfo->cinfo, COL_INFO)){
 594                                         col_append_fstr(pinfo->cinfo, COL_INFO, " IFPPacket#%u",ifp_packet_number);
 595                                 }
 596                         }
 597                 }
 598         }
 599
 600 }
 601
 602 static void
 603 dissect_t38_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 604 {
 605         primary_part = TRUE;
 606
 607         if(t38_tpkt_usage == T38_TPKT_ALWAYS){
 608                 dissect_tpkt_encap(tvb,pinfo,tree,t38_tpkt_reassembly,t38_tcp_pdu_handle);
 609         }
 610         else if((t38_tpkt_usage == T38_TPKT_NEVER) || (is_tpkt(tvb,1) == -1)){
 611                 dissect_t38_tcp_pdu(tvb, pinfo, tree);
 612         }
 613         else {
 614                 dissect_tpkt_encap(tvb,pinfo,tree,t38_tpkt_reassembly,t38_tcp_pdu_handle);
 615         }
 616 }
 617
 618 static void
 619 dissect_t38(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 620 {
 621         if(pinfo->ipproto == IP_PROTO_TCP)
 622         {
 623                 dissect_t38_tcp(tvb, pinfo, tree);
 624         }
 625         else if(pinfo->ipproto == IP_PROTO_UDP)
 626         {
 627                 dissect_t38_udp(tvb, pinfo, tree);
 628         }
 629 }
 630
 631 /* Look for conversation info and display any setup info found */
 632 void
 633 show_setup_info(tvbuff_t *tvb, proto_tree *tree, t38_conv *p_t38_conversation)
 634 {
 635         proto_tree *t38_setup_tree;
 636         proto_item *ti;
 637
 638         if (!p_t38_conversation || p_t38_conversation->setup_frame_number == 0) {
 639                 /* there is no Setup info */
 640                 return;
 641         }
 642
 643         ti =  proto_tree_add_string_format(tree, hf_t38_setup, tvb, 0, 0,
 644                       "",
 645                       "Stream setup by %s (frame %u)",
 646                       p_t38_conversation->setup_method,
 647                       p_t38_conversation->setup_frame_number);
 648     PROTO_ITEM_SET_GENERATED(ti);
 649     t38_setup_tree = proto_item_add_subtree(ti, ett_t38_setup);
 650     if (t38_setup_tree)
 651     {
 652                 /* Add details into subtree */
 653                 proto_item* item = proto_tree_add_uint(t38_setup_tree, hf_t38_setup_frame,
 654                                                                tvb, 0, 0, p_t38_conversation->setup_frame_number);
 655                 PROTO_ITEM_SET_GENERATED(item);
 656                 item = proto_tree_add_string(t38_setup_tree, hf_t38_setup_method,
 657                                                      tvb, 0, 0, p_t38_conversation->setup_method);
 658                 PROTO_ITEM_SET_GENERATED(item);
 659     }
 660 }
 661
 662
 663
 664 /* Wireshark Protocol Registration */
 665 void
 666 proto_register_t38(void)
 667 {
 668         static hf_register_info hf[] =
 669         {
 670 #include "packet-t38-hfarr.c"
 671                 {   &hf_t38_setup,
 672                     { "Stream setup", "t38.setup", FT_STRING, BASE_NONE,
 673                     NULL, 0x0, "Stream setup, method and frame number", HFILL }},
 674                 {   &hf_t38_setup_frame,
 675             { "Stream frame", "t38.setup-frame", FT_FRAMENUM, BASE_NONE,
 676             NULL, 0x0, "Frame that set up this stream", HFILL }},
 677         {   &hf_t38_setup_method,
 678             { "Stream Method", "t38.setup-method", FT_STRING, BASE_NONE,
 679             NULL, 0x0, "Method used to set up this stream", HFILL }},
 680                 {&hf_t38_fragments,
 681                         {"Message fragments", "t38.fragments",
 682                         FT_NONE, BASE_NONE, NULL, 0x00, NULL, HFILL } },
 683                 {&hf_t38_fragment,
 684                         {"Message fragment", "t38.fragment",
 685                         FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
 686                 {&hf_t38_fragment_overlap,
 687                         {"Message fragment overlap", "t38.fragment.overlap",
 688                         FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
 689                 {&hf_t38_fragment_overlap_conflicts,
 690                         {"Message fragment overlapping with conflicting data",
 691                         "t38.fragment.overlap.conflicts",
 692                         FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
 693                 {&hf_t38_fragment_multiple_tails,
 694                         {"Message has multiple tail fragments",
 695                         "t38.fragment.multiple_tails",
 696                         FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
 697                 {&hf_t38_fragment_too_long_fragment,
 698                         {"Message fragment too long", "t38.fragment.too_long_fragment",
 699                         FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
 700                 {&hf_t38_fragment_error,
 701                         {"Message defragmentation error", "t38.fragment.error",
 702                         FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
 703                 {&hf_t38_reassembled_in,
 704                         {"Reassembled in", "t38.reassembled.in",
 705                         FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
 706                 {&hf_t38_reassembled_length,
 707                         {"Reassembled T38 length", "t38.reassembled.length",
 708                         FT_UINT32, BASE_DEC, NULL, 0x00, NULL, HFILL } },
 709         };
 710
 711         static gint *ett[] =
 712         {
 713                 &ett_t38,
 714 #include "packet-t38-ettarr.c"
 715                 &ett_t38_setup,
 716                 &ett_data_fragment,
 717                 &ett_data_fragments
 718         };
 719
 720         module_t *t38_module;
 721
 722         proto_t38 = proto_register_protocol("T.38", "T.38", "t38");
 723         proto_register_field_array(proto_t38, hf, array_length(hf));
 724         proto_register_subtree_array(ett, array_length(ett));
 725         register_dissector("t38", dissect_t38, proto_t38);
 726
 727         /* Init reassemble tables for HDLC */
 728         register_init_routine(t38_defragment_init);
 729
 730         t38_tap = register_tap("t38");
 731
 732         t38_module = prefs_register_protocol(proto_t38, proto_reg_handoff_t38);
 733         prefs_register_bool_preference(t38_module, "use_pre_corrigendum_asn1_specification",
 734             "Use the Pre-Corrigendum ASN.1 specification",
 735             "Whether the T.38 dissector should decode using the Pre-Corrigendum T.38 "
 736                 "ASN.1 specification (1998).",
 737             &use_pre_corrigendum_asn1_specification);
 738         prefs_register_bool_preference(t38_module, "dissect_possible_rtpv2_packets_as_rtp",
 739             "Dissect possible RTP version 2 packets with RTP dissector",
 740             "Whether a UDP packet that looks like RTP version 2 packet will "
 741                 "be dissected as RTP packet or T.38 packet. If enabled there is a risk that T.38 UDPTL "
 742                 "packets with sequence number higher than 32767 may be dissected as RTP.",
 743             &dissect_possible_rtpv2_packets_as_rtp);
 744         prefs_register_uint_preference(t38_module, "tcp.port",
 745                 "T.38 TCP Port",
 746                 "Set the TCP port for T.38 messages",
 747                 10, &global_t38_tcp_port);
 748         prefs_register_uint_preference(t38_module, "udp.port",
 749                 "T.38 UDP Port",
 750                 "Set the UDP port for T.38 messages",
 751                 10, &global_t38_udp_port);
 752         prefs_register_bool_preference(t38_module, "reassembly",
 753                 "Reassemble T.38 PDUs over TPKT over TCP",
 754                 "Whether the dissector should reassemble T.38 PDUs spanning multiple TCP segments "
 755                 "when TPKT is used over TCP. "
 756                 "To use this option, you must also enable \"Allow subdissectors to reassemble "
 757                 "TCP streams\" in the TCP protocol settings.",
 758                 &t38_tpkt_reassembly);
 759         prefs_register_enum_preference(t38_module, "tpkt_usage",
 760                 "TPKT used over TCP",
 761                 "Whether T.38 is used with TPKT for TCP",
 762                 (gint *)&t38_tpkt_usage,t38_tpkt_options,FALSE);
 763
 764         prefs_register_bool_preference(t38_module, "show_setup_info",
 765                 "Show stream setup information",
 766                 "Where available, show which protocol and frame caused "
 767                 "this T.38 stream to be created",
 768                 &global_t38_show_setup_info);
 769
 770 }
 771
 772 void
 773 proto_reg_handoff_t38(void)
 774 {
 775         static gboolean t38_prefs_initialized = FALSE;
 776         static guint tcp_port;
 777         static guint udp_port;
 778
 779         if (!t38_prefs_initialized) {
 780                 t38_udp_handle=create_dissector_handle(dissect_t38_udp, proto_t38);
 781                 t38_tcp_handle=create_dissector_handle(dissect_t38_tcp, proto_t38);
 782                 t38_tcp_pdu_handle=create_dissector_handle(dissect_t38_tcp_pdu, proto_t38);
 783                 rtp_handle = find_dissector("rtp");
 784                 t30_hdlc_handle = find_dissector("t30.hdlc");
 785                 data_handle = find_dissector("data");
 786                 t38_prefs_initialized = TRUE;
 787         }
 788         else {
 789                 dissector_delete("tcp.port", tcp_port, t38_tcp_handle);
 790                 dissector_delete("udp.port", udp_port, t38_udp_handle);
 791         }
 792         tcp_port = global_t38_tcp_port;
 793         udp_port = global_t38_udp_port;
 794
 795         dissector_add("tcp.port", tcp_port, t38_tcp_handle);
 796         dissector_add("udp.port", udp_port, t38_udp_handle);
 797
 798 }
 799