path: root/epan/dissectors/packet-t38.c

/* Do not modify this file. Changes will be overwritten.                      */
/* Generated automatically by the ASN.1 to Wireshark dissector compiler       */
/* packet-t38.c                                                               */
/* asn2wrs.py -q -L -p t38 -c ./t38.cnf -s ./packet-t38-template -D . -O ../.. T38_2002.asn */

/* packet-t38.c
 * Routines for T.38 packet dissection
 * 2003  Hans Viens
 * 2004  Alejandro Vaquero, add support Conversations for SDP
 * 2006  Alejandro Vaquero, add T30 reassemble and dissection
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */


/* Depending on what ASN.1 specification is used you may have to change
 * the preference setting regarding Pre-Corrigendum ASN.1 specification:
 * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/1998/T38.html  (Pre-Corrigendum=true)
 * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2003/T38(1998).html (Pre-Corrigendum=true)
 *
 * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2003/T38(2002).html (Pre-Corrigendum=false)
 * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2002/t38.html  (Pre-Corrigendum=false)
 * http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2002-Amd1/T38.html (Pre-Corrigendum=false)
 */

/* TO DO:
 * - TCP desegmentation is currently not supported for T.38 IFP directly over TCP.
 * - H.245 dissectors should be updated to start conversations for T.38 similar to RTP.
 * - Sometimes the last octet is not high-lighted when selecting something in the tree. Bug in PER dissector?
 * - Add support for RTP payload audio/t38 (draft-jones-avt-audio-t38-03.txt), i.e. T38 in RTP packets.
 */


#include "config.h"

#include <epan/packet.h>
#include <epan/reassemble.h>
#include <epan/conversation.h>
#include <epan/tap.h>
#include <epan/expert.h>
#include <epan/strutil.h>
#include <epan/prefs.h>
#include <epan/ipproto.h>
#include <epan/asn1.h>
#include <epan/proto_data.h>
#include <wsutil/array.h>

#include "packet-t38.h"
#include "packet-per.h"
#include "packet-tpkt.h"
#include "packet-acdr.h"

void proto_register_t38(void);

static int t38_tap;

/* dissect using the Pre Corrigendum T.38 ASN.1 specification (1998) */
static bool use_pre_corrigendum_asn1_specification = true;

/* dissect packets that looks like RTP version 2 packets as RTP     */
/* instead of as T.38. This may result in that some T.38 UPTL       */
/* packets with sequence number values higher than 32767 may be     */
/* shown as RTP packets.                                            */
static bool dissect_possible_rtpv2_packets_as_rtp;


/* Reassembly of T.38 PDUs over TPKT over TCP */
static bool t38_tpkt_reassembly = true;

/* Preference setting whether TPKT header is used when sending T.38 over TCP.
 * The default setting is Maybe where the dissector will look on the first
 * bytes to try to determine whether TPKT header is used or not. This may not
 * work so well in some cases. You may want to change the setting to Always or
 * Newer.
 */
#define T38_TPKT_NEVER 0   /* Assume that there is never a TPKT header    */
#define T38_TPKT_ALWAYS 1  /* Assume that there is always a TPKT header   */
#define T38_TPKT_MAYBE 2   /* Assume TPKT if first octets are 03-00-xx-xx */
static int t38_tpkt_usage = T38_TPKT_MAYBE;

static const enum_val_t t38_tpkt_options[] = {
  {"never", "Never", T38_TPKT_NEVER},
  {"always", "Always", T38_TPKT_ALWAYS},
  {"maybe", "Maybe", T38_TPKT_MAYBE},
  {NULL, NULL, -1}
};



/* T38 */
static dissector_handle_t t38_udp_handle;
static dissector_handle_t t38_tcp_handle;
static dissector_handle_t t38_tcp_pdu_handle;
static dissector_handle_t rtp_handle;
static dissector_handle_t t30_hdlc_handle;
static dissector_handle_t data_handle;

static int32_t Type_of_msg_value;
static uint32_t Data_Field_field_type_value;
static uint32_t Data_value;
static uint32_t T30ind_value;
static uint32_t Data_Field_item_num;

static int proto_t38;
static int proto_acdr;
static int hf_t38_IFPPacket_PDU;                  /* IFPPacket */
static int hf_t38_UDPTLPacket_PDU;                /* UDPTLPacket */
static int hf_t38_type_of_msg;                    /* Type_of_msg */
static int hf_t38_data_field;                     /* Data_Field */
static int hf_t38_t30_indicator;                  /* T30_indicator */
static int hf_t38_t30_data;                       /* T30_data */
static int hf_t38_Data_Field_item;                /* Data_Field_item */
static int hf_t38_field_type;                     /* T_field_type */
static int hf_t38_field_data;                     /* T_field_data */
static int hf_t38_seq_number;                     /* T_seq_number */
static int hf_t38_primary_ifp_packet;             /* T_primary_ifp_packet */
static int hf_t38_error_recovery;                 /* T_error_recovery */
static int hf_t38_secondary_ifp_packets;          /* T_secondary_ifp_packets */
static int hf_t38_secondary_ifp_packets_item;     /* OpenType_IFPPacket */
static int hf_t38_fec_info;                       /* T_fec_info */
static int hf_t38_fec_npackets;                   /* INTEGER */
static int hf_t38_fec_data;                       /* T_fec_data */
static int hf_t38_fec_data_item;                  /* OCTET_STRING */

/* T38 setup fields */
static int hf_t38_setup;
static int hf_t38_setup_frame;
static int hf_t38_setup_method;

/* T38 Data reassemble fields */
static int hf_t38_fragments;
static int hf_t38_fragment;
static int hf_t38_fragment_overlap;
static int hf_t38_fragment_overlap_conflicts;
static int hf_t38_fragment_multiple_tails;
static int hf_t38_fragment_too_long_fragment;
static int hf_t38_fragment_error;
static int hf_t38_fragment_count;
static int hf_t38_reassembled_in;
static int hf_t38_reassembled_length;

static int ett_t38;
static int ett_t38_IFPPacket;
static int ett_t38_Type_of_msg;
static int ett_t38_Data_Field;
static int ett_t38_Data_Field_item;
static int ett_t38_UDPTLPacket;
static int ett_t38_T_error_recovery;
static int ett_t38_T_secondary_ifp_packets;
static int ett_t38_T_fec_info;
static int ett_t38_T_fec_data;
static int ett_t38_setup;

static int ett_data_fragment;
static int ett_data_fragments;

static expert_field ei_t38_malformed;

static bool primary_part = true;
static uint32_t seq_number;

/* Tables for reassembly of Data fragments. */
static reassembly_table data_reassembly_table;

static const fragment_items data_frag_items = {
	/* Fragment subtrees */
	&ett_data_fragment,
	&ett_data_fragments,
	/* Fragment fields */
	&hf_t38_fragments,
	&hf_t38_fragment,
	&hf_t38_fragment_overlap,
	&hf_t38_fragment_overlap_conflicts,
	&hf_t38_fragment_multiple_tails,
	&hf_t38_fragment_too_long_fragment,
	&hf_t38_fragment_error,
	&hf_t38_fragment_count,
	/* Reassembled in field */
	&hf_t38_reassembled_in,
	/* Reassembled length field */
	&hf_t38_reassembled_length,
	/* Reassembled data field */
	NULL,
	/* Tag */
	"Data fragments"
};

typedef struct _fragment_key {
	address src;
	address dst;
	uint32_t	id;
} fragment_key;

static conversation_t *p_conv;
static t38_conv *p_t38_conv;
static t38_conv *p_t38_packet_conv;
static t38_conv_info *p_t38_conv_info;
static t38_conv_info *p_t38_packet_conv_info;

/* RTP Version is the first 2 bits of the first octet in the UDP payload*/
#define RTP_VERSION(octet)	((octet) >> 6)

void proto_reg_handoff_t38(void);

static void show_setup_info(tvbuff_t *tvb, proto_tree *tree, t38_conv *p_t38_conv);
/* Preferences bool to control whether or not setup info should be shown */
static bool global_t38_show_setup_info = true;

/* Can tap up to 4 T38 packets within same packet */
/* We only tap the primary part, not the redundancy */
#define MAX_T38_MESSAGES_IN_PACKET 4
static t38_packet_info t38_info_arr[MAX_T38_MESSAGES_IN_PACKET];
static int t38_info_current=0;
static t38_packet_info *t38_info;


/* Set up an T38 conversation */
void t38_add_address(packet_info *pinfo,
                     address *addr, int port,
                     int other_port,
                     const char *setup_method, uint32_t setup_frame_number)
{
        address null_addr;
        conversation_t* p_conversation;
        t38_conv* p_conversation_data = NULL;

        /*
         * If this isn't the first time this packet has been processed,
         * we've already done this work, so we don't need to do it
         * again.
         */
        if ((pinfo->fd->visited) || (t38_udp_handle == NULL))
        {
                return;
        }

        clear_address(&null_addr);

        /*
         * Check if the ip address and port combination is not
         * already registered as a conversation.
         */
        p_conversation = find_conversation( setup_frame_number, addr, &null_addr, CONVERSATION_UDP, port, other_port,
                                NO_ADDR_B | (!other_port ? NO_PORT_B : 0));

        /*
         * If not, create a new conversation.
         */
        if ( !p_conversation || p_conversation->setup_frame != setup_frame_number) {
                p_conversation = conversation_new( setup_frame_number, addr, &null_addr, CONVERSATION_UDP,
                                           (uint32_t)port, (uint32_t)other_port,
                                                                   NO_ADDR2 | (!other_port ? NO_PORT2 : 0));
        }

        /* Set dissector */
        conversation_set_dissector(p_conversation, t38_udp_handle);

        /*
         * Check if the conversation has data associated with it.
         */
        p_conversation_data = (t38_conv*)conversation_get_proto_data(p_conversation, proto_t38);

        /*
         * If not, add a new data item.
         */
        if ( ! p_conversation_data ) {
                /* Create conversation data */
                p_conversation_data = wmem_new(wmem_file_scope(), t38_conv);

                conversation_add_proto_data(p_conversation, proto_t38, p_conversation_data);
        }

        /*
         * Update the conversation data.
         */
        (void) g_strlcpy(p_conversation_data->setup_method, setup_method, MAX_T38_SETUP_METHOD_SIZE);
        p_conversation_data->setup_frame_number = setup_frame_number;
        p_conversation_data->src_t38_info.reass_ID = 0;
        p_conversation_data->src_t38_info.reass_start_seqnum = -1;
        p_conversation_data->src_t38_info.reass_start_data_field = 0;
        p_conversation_data->src_t38_info.reass_data_type = 0;
        p_conversation_data->src_t38_info.last_seqnum = -1;
        p_conversation_data->src_t38_info.packet_lost = 0;
        p_conversation_data->src_t38_info.burst_lost = 0;
        p_conversation_data->src_t38_info.time_first_t4_data = 0;
        p_conversation_data->src_t38_info.additional_hdlc_data_field_counter = 0;
        p_conversation_data->src_t38_info.seqnum_prev_data_field = -1;
        p_conversation_data->src_t38_info.next = NULL;

        p_conversation_data->dst_t38_info.reass_ID = 0;
        p_conversation_data->dst_t38_info.reass_start_seqnum = -1;
        p_conversation_data->dst_t38_info.reass_start_data_field = 0;
        p_conversation_data->dst_t38_info.reass_data_type = 0;
        p_conversation_data->dst_t38_info.last_seqnum = -1;
        p_conversation_data->dst_t38_info.packet_lost = 0;
        p_conversation_data->dst_t38_info.burst_lost = 0;
        p_conversation_data->dst_t38_info.time_first_t4_data = 0;
        p_conversation_data->dst_t38_info.additional_hdlc_data_field_counter = 0;
        p_conversation_data->dst_t38_info.seqnum_prev_data_field = -1;
        p_conversation_data->dst_t38_info.next = NULL;
}


static fragment_head *
force_reassemble_seq(reassembly_table *table, packet_info *pinfo, uint32_t id)
{
	fragment_head *fd_head;
	fragment_item *fd_i;
	fragment_item *last_fd;
	uint32_t dfpos, size, packet_lost, burst_lost, seq_num;
	uint8_t *data;

	fd_head = fragment_get(table, pinfo, id, NULL);

	/* have we already seen this frame ?*/
	if (pinfo->fd->visited) {
		if (fd_head != NULL && fd_head->flags & FD_DEFRAGMENTED) {
			return fd_head;
		} else {
			return NULL;
		}
	}

	if (fd_head==NULL){
		/* we must have it to continue */
		return NULL;
	}

	/* check for packet lost and count the burst of packet lost */
	packet_lost = 0;
	burst_lost = 0;
	seq_num = 0;
	for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
		if (seq_num != fd_i->offset) {
			packet_lost += fd_i->offset - seq_num;
			if ( (fd_i->offset - seq_num) > burst_lost ) {
				burst_lost = fd_i->offset - seq_num;
			}
		}
		seq_num = fd_i->offset + 1;
	}

	/* we have received an entire packet, defragment it and
	 * free all fragments
	 */
	size=0;
	last_fd=NULL;
	for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
	  if(!last_fd || last_fd->offset!=fd_i->offset){
	    size+=fd_i->len;
	  }
	  last_fd=fd_i;
	}

	data = (uint8_t *) g_malloc(size);
	fd_head->tvb_data = tvb_new_real_data(data, size, size);
        tvb_set_free_cb(fd_head->tvb_data, g_free);
	fd_head->len = size;		/* record size for caller	*/

	/* add all data fragments */
	dfpos = 0;
	last_fd=NULL;
	for (fd_i=fd_head->next;fd_i && fd_i->len + dfpos <= size;fd_i=fd_i->next) {
	  if (fd_i->len) {
	    if(!last_fd || last_fd->offset!=fd_i->offset){
	      tvb_memcpy(fd_i->tvb_data, data+dfpos, 0, fd_i->len);
	      dfpos += fd_i->len;
	    } else {
	      /* duplicate/retransmission/overlap */
	      fd_i->flags    |= FD_OVERLAP;
	      fd_head->flags |= FD_OVERLAP;
	      if( (last_fd->len!=fd_i->len)
		  || tvb_memeql(last_fd->tvb_data, 0, tvb_get_ptr(fd_i->tvb_data, 0, last_fd->len), last_fd->len) ){
			fd_i->flags    |= FD_OVERLAPCONFLICT;
			fd_head->flags |= FD_OVERLAPCONFLICT;
	      }
	    }
	  }
	  last_fd=fd_i;
	}

	/* we have defragmented the pdu, now free all fragments*/
	for (fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
	  if(fd_i->tvb_data){
	    tvb_free(fd_i->tvb_data);
	    fd_i->tvb_data=NULL;
	  }
	}

	/* mark this packet as defragmented */
	fd_head->flags |= FD_DEFRAGMENTED;
	fd_head->reassembled_in=pinfo->num;

	col_append_fstr(pinfo->cinfo, COL_INFO, " (t4-data Reassembled: %d pack lost, %d pack burst lost)", packet_lost, burst_lost);

	p_t38_packet_conv_info->packet_lost = packet_lost;
	p_t38_packet_conv_info->burst_lost = burst_lost;

	return fd_head;
}

/* T38 Routines */

const value_string t38_T30_indicator_vals[] = {
  {   0, "no-signal" },
  {   1, "cng" },
  {   2, "ced" },
  {   3, "v21-preamble" },
  {   4, "v27-2400-training" },
  {   5, "v27-4800-training" },
  {   6, "v29-7200-training" },
  {   7, "v29-9600-training" },
  {   8, "v17-7200-short-training" },
  {   9, "v17-7200-long-training" },
  {  10, "v17-9600-short-training" },
  {  11, "v17-9600-long-training" },
  {  12, "v17-12000-short-training" },
  {  13, "v17-12000-long-training" },
  {  14, "v17-14400-short-training" },
  {  15, "v17-14400-long-training" },
  {  16, "v8-ansam" },
  {  17, "v8-signal" },
  {  18, "v34-cntl-channel-1200" },
  {  19, "v34-pri-channel" },
  {  20, "v34-CC-retrain" },
  {  21, "v33-12000-training" },
  {  22, "v33-14400-training" },
  { 0, NULL }
};


static int
dissect_t38_T30_indicator(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_enumerated(tvb, offset, actx, tree, hf_index,
                                     16, &T30ind_value, true, 7, NULL);

    if (primary_part){
        col_append_fstr(actx->pinfo->cinfo, COL_INFO, " t30ind: %s",
         val_to_str_const(T30ind_value,t38_T30_indicator_vals,"<unknown>"));
    }

    /* info for tap */
    if (primary_part)
        t38_info->t30ind_value = T30ind_value;
  return offset;
}


const value_string t38_T30_data_vals[] = {
  {   0, "v21" },
  {   1, "v27-2400" },
  {   2, "v27-4800" },
  {   3, "v29-7200" },
  {   4, "v29-9600" },
  {   5, "v17-7200" },
  {   6, "v17-9600" },
  {   7, "v17-12000" },
  {   8, "v17-14400" },
  {   9, "v8" },
  {  10, "v34-pri-rate" },
  {  11, "v34-CC-1200" },
  {  12, "v34-pri-ch" },
  {  13, "v33-12000" },
  {  14, "v33-14400" },
  { 0, NULL }
};


static int
dissect_t38_T30_data(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_enumerated(tvb, offset, actx, tree, hf_index,
                                     9, &Data_value, true, 6, NULL);

    if (primary_part){
        col_append_fstr(actx->pinfo->cinfo, COL_INFO, " data:%s:",
         val_to_str_const(Data_value,t38_T30_data_vals,"<unknown>"));
    }


    /* info for tap */
    if (primary_part)
        t38_info->data_value = Data_value;
  return offset;
}


static const value_string t38_Type_of_msg_vals[] = {
  {   0, "t30-indicator" },
  {   1, "t30-data" },
  { 0, NULL }
};

static const per_choice_t Type_of_msg_choice[] = {
  {   0, &hf_t38_t30_indicator   , ASN1_NO_EXTENSIONS     , dissect_t38_T30_indicator },
  {   1, &hf_t38_t30_data        , ASN1_NO_EXTENSIONS     , dissect_t38_T30_data },
  { 0, NULL, 0, NULL }
};

static int
dissect_t38_Type_of_msg(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_choice(tvb, offset, actx, tree, hf_index,
                                 ett_t38_Type_of_msg, Type_of_msg_choice,
                                 &Type_of_msg_value);

  /* info for tap */
  if (primary_part)
    t38_info->type_msg = Type_of_msg_value;
  return offset;
}


static const value_string t38_T_field_type_vals[] = {
  {   0, "hdlc-data" },
  {   1, "hdlc-sig-end" },
  {   2, "hdlc-fcs-OK" },
  {   3, "hdlc-fcs-BAD" },
  {   4, "hdlc-fcs-OK-sig-end" },
  {   5, "hdlc-fcs-BAD-sig-end" },
  {   6, "t4-non-ecm-data" },
  {   7, "t4-non-ecm-sig-end" },
  {   8, "cm-message" },
  {   9, "jm-message" },
  {  10, "ci-message" },
  {  11, "v34rate" },
  { 0, NULL }
};


static int
dissect_t38_T_field_type(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_enumerated(tvb, offset, actx, tree, hf_index,
                                     8, &Data_Field_field_type_value, (use_pre_corrigendum_asn1_specification)?false:true, (use_pre_corrigendum_asn1_specification)?0:4, NULL);

    if (primary_part){
        col_append_fstr(actx->pinfo->cinfo, COL_INFO, " %s",
         val_to_str_const(Data_Field_field_type_value,t38_T_field_type_vals,"<unknown>"));
    }

    if (primary_part) {
        if (Data_Field_field_type_value == 2 || Data_Field_field_type_value == 4 || Data_Field_field_type_value == 7) {/* hdlc-fcs-OK or hdlc-fcs-OK-sig-end or t4-non-ecm-sig-end*/
            fragment_head *frag_msg = NULL;
            tvbuff_t* new_tvb = NULL;
            bool save_fragmented = actx->pinfo->fragmented;

            actx->pinfo->fragmented = true;

            /* if reass_start_seqnum=-1 it means we have received the end of the fragmente, without received any fragment data */
            if (p_t38_packet_conv_info->reass_start_seqnum != -1) {
                uint32_t frag_seq_num;
                if (seq_number == (uint32_t)p_t38_packet_conv_info->reass_start_seqnum) {
                    frag_seq_num = (uint32_t)p_t38_packet_conv_info->additional_hdlc_data_field_counter + Data_Field_item_num - p_t38_packet_conv_info->reass_start_data_field;
                } else {
                    frag_seq_num = seq_number - (uint32_t)p_t38_packet_conv_info->reass_start_seqnum + (uint32_t)p_t38_packet_conv_info->additional_hdlc_data_field_counter + Data_Field_item_num;
                }
                frag_msg = fragment_add_seq(&data_reassembly_table, /* reassembly table */
                    tvb, offset, actx->pinfo,
                    p_t38_packet_conv_info->reass_ID, /* ID for fragments belonging together */
                    NULL,
                    frag_seq_num,  /* fragment sequence number */
                    /*0,*/
                    0, /* fragment length */
                    false, /* More fragments */
                    0);
                if ( Data_Field_field_type_value == 7 ) {
                    /* if there was packet lost or other errors during the defrag then frag_msg is NULL. This could also means
                     * there are out of order packets (e.g, got the tail frame t4-non-ecm-sig-end before the last fragment),
                     * but we will assume there was packet lost instead, which is more usual. So, we are going to reassemble the packet
                     * and get some stat, like packet lost and burst number of packet lost
                    */
                    if (!frag_msg) {
                        force_reassemble_seq(&data_reassembly_table, /* reassembly table */
                            actx->pinfo,
                            p_t38_packet_conv_info->reass_ID /* ID for fragments belonging together */
                        );
                    } else {
                        col_append_str(actx->pinfo->cinfo, COL_INFO, " (t4-data Reassembled: No packet lost)");

                        snprintf(t38_info->desc_comment, MAX_T38_DESC, "No packet lost");
                    }


                    if (p_t38_packet_conv_info->packet_lost) {
                        snprintf(t38_info->desc_comment, MAX_T38_DESC, " Pack lost: %d, Pack burst lost: %d", p_t38_packet_conv_info->packet_lost, p_t38_packet_conv_info->burst_lost);
                    } else {
                        snprintf(t38_info->desc_comment, MAX_T38_DESC, "No packet lost");
                    }

                    process_reassembled_data(tvb, offset, actx->pinfo,
                                "Reassembled T38", frag_msg, &data_frag_items, NULL, tree);

                    /* Now reset fragmentation information in pinfo */
                    actx->pinfo->fragmented = save_fragmented;

                    t38_info->time_first_t4_data = p_t38_packet_conv_info->time_first_t4_data;
                    t38_info->frame_num_first_t4_data = p_t38_packet_conv_info->reass_ID; /* The reass_ID is the Frame number of the first t4 fragment */

                } else {
                    new_tvb = process_reassembled_data(tvb, offset, actx->pinfo,
                                "Reassembled T38", frag_msg, &data_frag_items, NULL, tree);

                    /* Now reset fragmentation information in pinfo */
                    actx->pinfo->fragmented = save_fragmented;

                    if (new_tvb) call_dissector_with_data((t30_hdlc_handle) ? t30_hdlc_handle : data_handle, new_tvb, actx->pinfo, tree, t38_info);
                }
            } else {
                /* If this is the same sequence number as the previous packet
                 * (i.e., a retransmission), we don't expect to have any
                 * fragment data (we reassembled it in the previous packet).
                 */
                if (p_t38_packet_conv && ((int32_t) seq_number != p_t38_packet_conv_info->last_seqnum)) {
                    proto_tree_add_expert_format(tree, actx->pinfo, &ei_t38_malformed, tvb, offset, tvb_reported_length_remaining(tvb, offset),
                            "[RECEIVED END OF FRAGMENT W/OUT ANY FRAGMENT DATA]");
                    col_append_str(actx->pinfo->cinfo, COL_INFO, " [Malformed?]");
                }
                actx->pinfo->fragmented = save_fragmented;
            }
        }

        /* reset the reassemble ID and the start seq number if it is not HDLC data */
        if ( p_t38_conv && ( ((Data_Field_field_type_value >0) && (Data_Field_field_type_value <6)) || (Data_Field_field_type_value == 7) ) ){
            p_t38_conv_info->reass_ID = 0;
            p_t38_conv_info->reass_start_seqnum = -1;
            p_t38_conv_info->additional_hdlc_data_field_counter = 0;
            p_t38_conv_info->seqnum_prev_data_field = -1;

            if (p_t38_packet_conv_info->next == NULL) {
                p_t38_packet_conv_info->next = wmem_new(wmem_file_scope(), t38_conv_info);
                p_t38_packet_conv_info = p_t38_packet_conv_info->next;
                memcpy(p_t38_packet_conv_info, p_t38_conv_info, sizeof(t38_conv_info));
            }

        }
        t38_info->Data_Field_field_type_value = Data_Field_field_type_value;
    }
  return offset;
}



static int
dissect_t38_T_field_data(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
    tvbuff_t *value_tvb = NULL;
    uint32_t value_len;

  offset = dissect_per_octet_string(tvb, offset, actx, tree, hf_index,
                                       1, 65535, false, &value_tvb);

    value_len = tvb_reported_length(value_tvb);


    if (primary_part){
        if(value_len < 8){
            col_append_fstr(actx->pinfo->cinfo, COL_INFO, "[%s]",
               tvb_bytes_to_str(actx->pinfo->pool, value_tvb,0,value_len));
        }
        else {
            col_append_fstr(actx->pinfo->cinfo, COL_INFO, "[%s...]",
               tvb_bytes_to_str(actx->pinfo->pool, value_tvb,0,7));
        }
    }

    if (primary_part) {
        fragment_head *frag_msg = NULL;

        /* HDLC Data or t4-non-ecm-data */
        if (Data_Field_field_type_value == 0 || Data_Field_field_type_value == 6) { /* 0=HDLC Data or 6=t4-non-ecm-data*/
            bool save_fragmented = actx->pinfo->fragmented;

            actx->pinfo->fragmented = true;

            /* if we have not reassembled this packet and it is the first fragment, reset the reassemble ID and the start seq number*/
            if (p_t38_packet_conv && p_t38_conv && (p_t38_packet_conv_info->reass_start_seqnum == -1)) {
                /* we use the first fragment's frame_number as fragment ID because the protocol doesn't provide it */
                /* XXX: We'd be better off assigning our own IDs using a one-up
                 * counter, if it's possible for more than one reassembly to
                 * begin in the same frame.
                 */
                    p_t38_conv_info->reass_ID = actx->pinfo->num;
                    p_t38_conv_info->reass_start_seqnum = seq_number;
                    p_t38_conv_info->time_first_t4_data = nstime_to_sec(&actx->pinfo->rel_ts);
                    p_t38_conv_info->additional_hdlc_data_field_counter = 0;
                    p_t38_packet_conv_info->reass_ID = p_t38_conv_info->reass_ID;
                    p_t38_packet_conv_info->reass_start_seqnum = p_t38_conv_info->reass_start_seqnum;
                    p_t38_packet_conv_info->reass_start_data_field = Data_Field_item_num;
                    p_t38_packet_conv_info->seqnum_prev_data_field = p_t38_conv_info->seqnum_prev_data_field;
                    p_t38_packet_conv_info->additional_hdlc_data_field_counter = p_t38_conv_info->additional_hdlc_data_field_counter;
                    p_t38_packet_conv_info->time_first_t4_data = p_t38_conv_info->time_first_t4_data;
            }
            if (seq_number == (uint32_t)p_t38_packet_conv_info->seqnum_prev_data_field){
                   if(p_t38_conv){
                     p_t38_conv_info->additional_hdlc_data_field_counter++;
                   }
	    }
            uint32_t frag_seq_num;
            if (seq_number == (uint32_t)p_t38_packet_conv_info->reass_start_seqnum) {
                frag_seq_num = (uint32_t)p_t38_packet_conv_info->additional_hdlc_data_field_counter + Data_Field_item_num - (uint32_t)p_t38_packet_conv_info->reass_start_data_field;
            } else {
                frag_seq_num = seq_number - (uint32_t)p_t38_packet_conv_info->reass_start_seqnum + (uint32_t)p_t38_packet_conv_info->additional_hdlc_data_field_counter + Data_Field_item_num;
            }
            frag_msg = fragment_add_seq(&data_reassembly_table,
                value_tvb, 0,
                actx->pinfo,
                p_t38_packet_conv_info->reass_ID, /* ID for fragments belonging together */
                NULL,
                frag_seq_num, /* fragment sequence number */
                value_len, /* fragment length */
                true, /* More fragments */
                0);
            p_t38_packet_conv_info->seqnum_prev_data_field = (int32_t)seq_number;
            process_reassembled_data(tvb, offset, actx->pinfo,
                        "Reassembled T38", frag_msg, &data_frag_items, NULL, tree);

            if (!frag_msg) { /* Not last packet of reassembled */
                if (Data_Field_field_type_value == 0) {
                    col_append_fstr(actx->pinfo->cinfo, COL_INFO," (HDLC fragment %u)", frag_seq_num);
                } else {
                    col_append_fstr(actx->pinfo->cinfo, COL_INFO," (t4-data fragment %u)", seq_number - (uint32_t)p_t38_packet_conv_info->reass_start_seqnum);
                }
            }

            /* Now reset fragmentation information in pinfo */
            actx->pinfo->fragmented = save_fragmented;
        }
    }
  return offset;
}


static const per_sequence_t Data_Field_item_sequence[] = {
  { &hf_t38_field_type      , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_T_field_type },
  { &hf_t38_field_data      , ASN1_NO_EXTENSIONS     , ASN1_OPTIONAL    , dissect_t38_T_field_data },
  { NULL, 0, 0, NULL }
};

static int
dissect_t38_Data_Field_item(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence(tvb, offset, actx, tree, hf_index,
                                   ett_t38_Data_Field_item, Data_Field_item_sequence);

    if (primary_part) Data_Field_item_num++;
  return offset;
}


static const per_sequence_t Data_Field_sequence_of[1] = {
  { &hf_t38_Data_Field_item , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_Data_Field_item },
};

static int
dissect_t38_Data_Field(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence_of(tvb, offset, actx, tree, hf_index,
                                      ett_t38_Data_Field, Data_Field_sequence_of);

  return offset;
}


static const per_sequence_t IFPPacket_sequence[] = {
  { &hf_t38_type_of_msg     , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_Type_of_msg },
  { &hf_t38_data_field      , ASN1_NO_EXTENSIONS     , ASN1_OPTIONAL    , dissect_t38_Data_Field },
  { NULL, 0, 0, NULL }
};

static int
dissect_t38_IFPPacket(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence(tvb, offset, actx, tree, hf_index,
                                   ett_t38_IFPPacket, IFPPacket_sequence);

  return offset;
}



static int
dissect_t38_T_seq_number(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_constrained_integer(tvb, offset, actx, tree, hf_index,
                                                            0U, 65535U, &seq_number, false);

    /* info for tap */
    if (primary_part)
        t38_info->seq_num = seq_number;

    col_append_fstr(actx->pinfo->cinfo, COL_INFO, "Seq=%05u ",seq_number);
  return offset;
}



static int
dissect_t38_T_primary_ifp_packet(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
    primary_part = true;
  offset = dissect_per_open_type(tvb, offset, actx, tree, hf_index, dissect_t38_IFPPacket);

    /* if is a valid t38 packet, add to tap */
    /* Note that t4-non-ecm-sig-end without first_t4_data is not valid */
    if (p_t38_packet_conv && (!actx->pinfo->flags.in_error_pkt) && ((int32_t) seq_number != p_t38_packet_conv_info->last_seqnum) &&
        !(t38_info->type_msg == 1 && t38_info->Data_Field_field_type_value == 7 && t38_info->frame_num_first_t4_data == 0))
        tap_queue_packet(t38_tap, actx->pinfo, t38_info);

    if (p_t38_conv) p_t38_conv_info->last_seqnum = (int32_t) seq_number;
  return offset;
}



static int
dissect_t38_OpenType_IFPPacket(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_open_type(tvb, offset, actx, tree, hf_index, dissect_t38_IFPPacket);

  return offset;
}


static const per_sequence_t T_secondary_ifp_packets_sequence_of[1] = {
  { &hf_t38_secondary_ifp_packets_item, ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_OpenType_IFPPacket },
};

static int
dissect_t38_T_secondary_ifp_packets(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence_of(tvb, offset, actx, tree, hf_index,
                                      ett_t38_T_secondary_ifp_packets, T_secondary_ifp_packets_sequence_of);

  return offset;
}



static int
dissect_t38_INTEGER(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_integer(tvb, offset, actx, tree, hf_index, NULL);

  return offset;
}



static int
dissect_t38_OCTET_STRING(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_octet_string(tvb, offset, actx, tree, hf_index,
                                       NO_BOUND, NO_BOUND, false, NULL);

  return offset;
}


static const per_sequence_t T_fec_data_sequence_of[1] = {
  { &hf_t38_fec_data_item   , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_OCTET_STRING },
};

static int
dissect_t38_T_fec_data(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence_of(tvb, offset, actx, tree, hf_index,
                                      ett_t38_T_fec_data, T_fec_data_sequence_of);

  return offset;
}


static const per_sequence_t T_fec_info_sequence[] = {
  { &hf_t38_fec_npackets    , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_INTEGER },
  { &hf_t38_fec_data        , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_T_fec_data },
  { NULL, 0, 0, NULL }
};

static int
dissect_t38_T_fec_info(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
  offset = dissect_per_sequence(tvb, offset, actx, tree, hf_index,
                                   ett_t38_T_fec_info, T_fec_info_sequence);

  return offset;
}


static const value_string t38_T_error_recovery_vals[] = {
  {   0, "secondary-ifp-packets" },
  {   1, "fec-info" },
  { 0, NULL }
};

static const per_choice_t T_error_recovery_choice[] = {
  {   0, &hf_t38_secondary_ifp_packets, ASN1_NO_EXTENSIONS     , dissect_t38_T_secondary_ifp_packets },
  {   1, &hf_t38_fec_info        , ASN1_NO_EXTENSIONS     , dissect_t38_T_fec_info },
  { 0, NULL, 0, NULL }
};

static int
dissect_t38_T_error_recovery(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
    primary_part = false;
  offset = dissect_per_choice(tvb, offset, actx, tree, hf_index,
                                 ett_t38_T_error_recovery, T_error_recovery_choice,
                                 NULL);

    primary_part = true;
  return offset;
}


static const per_sequence_t UDPTLPacket_sequence[] = {
  { &hf_t38_seq_number      , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_T_seq_number },
  { &hf_t38_primary_ifp_packet, ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_T_primary_ifp_packet },
  { &hf_t38_error_recovery  , ASN1_NO_EXTENSIONS     , ASN1_NOT_OPTIONAL, dissect_t38_T_error_recovery },
  { NULL, 0, 0, NULL }
};

static int
dissect_t38_UDPTLPacket(tvbuff_t *tvb _U_, int offset _U_, asn1_ctx_t *actx _U_, proto_tree *tree _U_, int hf_index _U_) {
    /* Initialize to something else than data type */
    Data_Field_field_type_value = 1;
  offset = dissect_per_sequence(tvb, offset, actx, tree, hf_index,
                                   ett_t38_UDPTLPacket, UDPTLPacket_sequence);

  return offset;
}

/*--- PDUs ---*/

static int dissect_IFPPacket_PDU(tvbuff_t *tvb _U_, packet_info *pinfo _U_, proto_tree *tree _U_, void *data _U_) {
  int offset = 0;
  asn1_ctx_t asn1_ctx;
  asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
  offset = dissect_t38_IFPPacket(tvb, offset, &asn1_ctx, tree, hf_t38_IFPPacket_PDU);
  offset += 7; offset >>= 3;
  return offset;
}
static int dissect_UDPTLPacket_PDU(tvbuff_t *tvb _U_, packet_info *pinfo _U_, proto_tree *tree _U_, void *data _U_) {
  int offset = 0;
  asn1_ctx_t asn1_ctx;
  asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
  offset = dissect_t38_UDPTLPacket(tvb, offset, &asn1_ctx, tree, hf_t38_UDPTLPacket_PDU);
  offset += 7; offset >>= 3;
  return offset;
}


/* initialize the tap t38_info and the conversation */
static void
init_t38_info_conv(packet_info *pinfo)
{
	/* tap info */
	t38_info_current++;
	if (t38_info_current==MAX_T38_MESSAGES_IN_PACKET) {
		t38_info_current=0;
	}
	t38_info = &t38_info_arr[t38_info_current];

	t38_info->seq_num = 0;
	t38_info->type_msg = 0;
	t38_info->data_value = 0;
	t38_info->t30ind_value =0;
	t38_info->setup_frame_number = 0;
	t38_info->Data_Field_field_type_value = 0;
	t38_info->desc[0] = '\0';
	t38_info->desc_comment[0] = '\0';
	t38_info->time_first_t4_data = 0;
	t38_info->frame_num_first_t4_data = 0;


	/*
		p_t38_packet_conv hold the conversation info in each of the packets.
		p_t38_conv hold the conversation info used to reassemble the HDLC packets, and also the Setup info (e.g SDP)
		If we already have p_t38_packet_conv in the packet, it means we already reassembled the HDLC packets, so we don't
		need to use p_t38_conv
	*/
	p_t38_packet_conv = NULL;
	p_t38_conv = NULL;

	/* Use existing packet info if available */
	p_t38_packet_conv = (t38_conv *)p_get_proto_data(wmem_file_scope(), pinfo, proto_t38, 0);


	/* find the conversation used for Reassemble and Setup Info */
	p_conv = find_conversation(pinfo->num, &pinfo->net_dst, &pinfo->net_src,
                                   conversation_pt_to_conversation_type(pinfo->ptype),
                                   pinfo->destport, pinfo->srcport, NO_ADDR_B | NO_PORT_B);

	/* create a conv if it doesn't exist */
	if (!p_conv) {
		p_conv = conversation_new(pinfo->num, &pinfo->net_src, &pinfo->net_dst,
			      conversation_pt_to_conversation_type(pinfo->ptype), pinfo->srcport, pinfo->destport, NO_ADDR2 | NO_PORT2);

		/* Set dissector */
		conversation_set_dissector(p_conv, t38_udp_handle);
	}

	p_t38_conv = (t38_conv *)conversation_get_proto_data(p_conv, proto_t38);

	/* create the conversation if it doesn't exist */
	if (!p_t38_conv) {
		p_t38_conv = wmem_new(wmem_file_scope(), t38_conv);
		p_t38_conv->setup_method[0] = '\0';
		p_t38_conv->setup_frame_number = 0;

		p_t38_conv->src_t38_info.reass_ID = 0;
		p_t38_conv->src_t38_info.reass_start_seqnum = -1;
		p_t38_conv->src_t38_info.reass_start_data_field = 0;
		p_t38_conv->src_t38_info.reass_data_type = 0;
		p_t38_conv->src_t38_info.last_seqnum = -1;
		p_t38_conv->src_t38_info.packet_lost = 0;
		p_t38_conv->src_t38_info.burst_lost = 0;
		p_t38_conv->src_t38_info.time_first_t4_data = 0;
		p_t38_conv->src_t38_info.additional_hdlc_data_field_counter = 0;
		p_t38_conv->src_t38_info.seqnum_prev_data_field = -1;
		p_t38_conv->src_t38_info.next = NULL;

		p_t38_conv->dst_t38_info.reass_ID = 0;
		p_t38_conv->dst_t38_info.reass_start_seqnum = -1;
		p_t38_conv->dst_t38_info.reass_start_data_field = 0;
		p_t38_conv->dst_t38_info.reass_data_type = 0;
		p_t38_conv->dst_t38_info.last_seqnum = -1;
		p_t38_conv->dst_t38_info.packet_lost = 0;
		p_t38_conv->dst_t38_info.burst_lost = 0;
		p_t38_conv->dst_t38_info.time_first_t4_data = 0;
		p_t38_conv->dst_t38_info.additional_hdlc_data_field_counter = 0;
		p_t38_conv->dst_t38_info.seqnum_prev_data_field = -1;
		p_t38_conv->dst_t38_info.next = NULL;

		conversation_add_proto_data(p_conv, proto_t38, p_t38_conv);
	}

	if (!p_t38_packet_conv) {
		/* copy the t38 conversation info to the packet t38 conversation */
		p_t38_packet_conv = wmem_new(wmem_file_scope(), t38_conv);
		(void) g_strlcpy(p_t38_packet_conv->setup_method, p_t38_conv->setup_method, MAX_T38_SETUP_METHOD_SIZE);
		p_t38_packet_conv->setup_frame_number = p_t38_conv->setup_frame_number;

		memcpy(&(p_t38_packet_conv->src_t38_info), &(p_t38_conv->src_t38_info), sizeof(t38_conv_info));
		memcpy(&(p_t38_packet_conv->dst_t38_info), &(p_t38_conv->dst_t38_info), sizeof(t38_conv_info));

		p_add_proto_data(wmem_file_scope(), pinfo, proto_t38, 0, p_t38_packet_conv);
	}

	if (addresses_equal(conversation_key_addr1(p_conv->key_ptr), &pinfo->net_src)) {
		p_t38_conv_info = &(p_t38_conv->src_t38_info);
		p_t38_packet_conv_info = &(p_t38_packet_conv->src_t38_info);
	} else {
		p_t38_conv_info = &(p_t38_conv->dst_t38_info);
		p_t38_packet_conv_info = &(p_t38_packet_conv->dst_t38_info);
	}

	/* update t38_info */
	t38_info->setup_frame_number = p_t38_packet_conv->setup_frame_number;
}

/* Entry point for dissection */
static int
dissect_t38_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	uint8_t octet1;
	proto_item *it;
	proto_tree *tr;
	uint32_t offset=0;

	/*
	 * XXX - heuristic to check for misidentified packets.
	 */
	if (dissect_possible_rtpv2_packets_as_rtp){
		octet1 = tvb_get_uint8(tvb, offset);
		if (RTP_VERSION(octet1) == 2){
			return call_dissector(rtp_handle,tvb,pinfo,tree);
		}
	}

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.38");
	col_clear(pinfo->cinfo, COL_INFO);

	primary_part = true;

	/* This indicate the item number in the primary part of the T38 message, it is used for the reassemble of T30 packets */
	Data_Field_item_num = 0;

	it=proto_tree_add_protocol_format(tree, proto_t38, tvb, 0, -1, "ITU-T Recommendation T.38");
	tr=proto_item_add_subtree(it, ett_t38);

	/* init tap and conv info */
	init_t38_info_conv(pinfo);

	/* Show Conversation setup info if exists*/
	if (global_t38_show_setup_info) {
		show_setup_info(tvb, tr, p_t38_packet_conv);
	}

	col_append_str(pinfo->cinfo, COL_INFO, "UDP: UDPTLPacket ");

	offset = dissect_UDPTLPacket_PDU(tvb, pinfo, tr, NULL);

	if (tvb_reported_length_remaining(tvb,offset)>0){
		proto_tree_add_expert_format(tr, pinfo, &ei_t38_malformed, tvb, offset, tvb_reported_length_remaining(tvb, offset),
				"[MALFORMED PACKET or wrong preference settings]");
		col_append_str(pinfo->cinfo, COL_INFO, " [Malformed?]");
	}
	return tvb_captured_length(tvb);
}

static int
dissect_t38_tcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	proto_item *it;
	proto_tree *tr;
	uint32_t offset=0;
        tvbuff_t *next_tvb;
	uint16_t ifp_packet_number=1;

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.38");
	col_clear(pinfo->cinfo, COL_INFO);

	primary_part = true;

	/* This indicate the item number in the primary part of the T38 message, it is used for the reassemble of T30 packets */
	Data_Field_item_num = 0;

	it=proto_tree_add_protocol_format(tree, proto_t38, tvb, 0, -1, "ITU-T Recommendation T.38");
	tr=proto_item_add_subtree(it, ett_t38);

	/* init tap and conv info */
	init_t38_info_conv(pinfo);

	/* Show Conversation setup info if exists*/
	if (global_t38_show_setup_info) {
		show_setup_info(tvb, tr, p_t38_packet_conv);
	}

	col_append_str(pinfo->cinfo, COL_INFO, "TCP: IFPPacket");

	while(tvb_reported_length_remaining(tvb,offset)>0)
	{
		next_tvb = tvb_new_subset_remaining(tvb, offset);
		offset += dissect_IFPPacket_PDU(next_tvb, pinfo, tr, NULL);
		ifp_packet_number++;

		if(tvb_reported_length_remaining(tvb,offset)>0){
			if(t38_tpkt_usage == T38_TPKT_ALWAYS){
				proto_tree_add_expert_format(tr, pinfo, &ei_t38_malformed, tvb, offset, tvb_reported_length_remaining(tvb, offset),
						"[MALFORMED PACKET or wrong preference settings]");
				col_append_str(pinfo->cinfo, COL_INFO, " [Malformed?]");
				break;
			}else {
				col_append_fstr(pinfo->cinfo, COL_INFO, " IFPPacket#%u",ifp_packet_number);
			}
		}
	}

	return tvb_captured_length(tvb);
}

static int
dissect_t38_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	primary_part = true;

	if(t38_tpkt_usage == T38_TPKT_ALWAYS){
		dissect_tpkt_encap(tvb,pinfo,tree,t38_tpkt_reassembly,t38_tcp_pdu_handle);
	}
	else if((t38_tpkt_usage == T38_TPKT_NEVER) || (is_tpkt(tvb,1) == -1)){
		dissect_t38_tcp_pdu(tvb, pinfo, tree, data);
	}
	else {
		dissect_tpkt_encap(tvb,pinfo,tree,t38_tpkt_reassembly,t38_tcp_pdu_handle);
	}
	return tvb_captured_length(tvb);
}

/* Look for conversation info and display any setup info found */
void
show_setup_info(tvbuff_t *tvb, proto_tree *tree, t38_conv *p_t38_conversation)
{
	proto_tree *t38_setup_tree;
	proto_item *ti;

	if (!p_t38_conversation || p_t38_conversation->setup_frame_number == 0) {
		/* there is no Setup info */
		return;
	}

	ti =  proto_tree_add_string_format(tree, hf_t38_setup, tvb, 0, 0,
                      "",
                      "Stream setup by %s (frame %u)",
                      p_t38_conversation->setup_method,
                      p_t38_conversation->setup_frame_number);
    proto_item_set_generated(ti);
    t38_setup_tree = proto_item_add_subtree(ti, ett_t38_setup);
    if (t38_setup_tree)
    {
		/* Add details into subtree */
		proto_item* item = proto_tree_add_uint(t38_setup_tree, hf_t38_setup_frame,
                                                               tvb, 0, 0, p_t38_conversation->setup_frame_number);
		proto_item_set_generated(item);
		item = proto_tree_add_string(t38_setup_tree, hf_t38_setup_method,
                                                     tvb, 0, 0, p_t38_conversation->setup_method);
		proto_item_set_generated(item);
    }
}

/* This function tries to understand if the payload is sitting on top of AC DR */
static bool
dissect_t38_acdr_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
	unsigned acdr_prot = GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_acdr, 0));
	if (acdr_prot == ACDR_T38)
		return dissect_t38_udp(tvb, pinfo, tree, data);
	return false;
}


/* Wireshark Protocol Registration */
void
proto_register_t38(void)
{
	static hf_register_info hf[] =
	{
    { &hf_t38_IFPPacket_PDU,
      { "IFPPacket", "t38.IFPPacket_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_UDPTLPacket_PDU,
      { "UDPTLPacket", "t38.UDPTLPacket_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_type_of_msg,
      { "type-of-msg", "t38.type_of_msg",
        FT_UINT32, BASE_DEC, VALS(t38_Type_of_msg_vals), 0,
        NULL, HFILL }},
    { &hf_t38_data_field,
      { "data-field", "t38.data_field",
        FT_UINT32, BASE_DEC, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_t30_indicator,
      { "t30-indicator", "t38.t30_indicator",
        FT_UINT32, BASE_DEC, VALS(t38_T30_indicator_vals), 0,
        NULL, HFILL }},
    { &hf_t38_t30_data,
      { "t30-data", "t38.t30_data",
        FT_UINT32, BASE_DEC, VALS(t38_T30_data_vals), 0,
        NULL, HFILL }},
    { &hf_t38_Data_Field_item,
      { "Data-Field item", "t38.Data_Field_item_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_field_type,
      { "field-type", "t38.field_type",
        FT_UINT32, BASE_DEC, VALS(t38_T_field_type_vals), 0,
        NULL, HFILL }},
    { &hf_t38_field_data,
      { "field-data", "t38.field_data",
        FT_BYTES, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_seq_number,
      { "seq-number", "t38.seq_number",
        FT_UINT32, BASE_DEC, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_primary_ifp_packet,
      { "primary-ifp-packet", "t38.primary_ifp_packet_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_error_recovery,
      { "error-recovery", "t38.error_recovery",
        FT_UINT32, BASE_DEC, VALS(t38_T_error_recovery_vals), 0,
        NULL, HFILL }},
    { &hf_t38_secondary_ifp_packets,
      { "secondary-ifp-packets", "t38.secondary_ifp_packets",
        FT_UINT32, BASE_DEC, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_secondary_ifp_packets_item,
      { "secondary-ifp-packets item", "t38.secondary_ifp_packets_item_element",
        FT_NONE, BASE_NONE, NULL, 0,
        "OpenType_IFPPacket", HFILL }},
    { &hf_t38_fec_info,
      { "fec-info", "t38.fec_info_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_fec_npackets,
      { "fec-npackets", "t38.fec_npackets",
        FT_INT32, BASE_DEC, NULL, 0,
        "INTEGER", HFILL }},
    { &hf_t38_fec_data,
      { "fec-data", "t38.fec_data",
        FT_UINT32, BASE_DEC, NULL, 0,
        NULL, HFILL }},
    { &hf_t38_fec_data_item,
      { "fec-data item", "t38.fec_data_item",
        FT_BYTES, BASE_NONE, NULL, 0,
        "OCTET_STRING", HFILL }},
		{   &hf_t38_setup,
		    { "Stream setup", "t38.setup", FT_STRING, BASE_NONE,
		    NULL, 0x0, "Stream setup, method and frame number", HFILL }},
		{   &hf_t38_setup_frame,
            { "Stream frame", "t38.setup-frame", FT_FRAMENUM, BASE_NONE,
            NULL, 0x0, "Frame that set up this stream", HFILL }},
        {   &hf_t38_setup_method,
            { "Stream Method", "t38.setup-method", FT_STRING, BASE_NONE,
            NULL, 0x0, "Method used to set up this stream", HFILL }},
		{&hf_t38_fragments,
			{"Message fragments", "t38.fragments",
			FT_NONE, BASE_NONE, NULL, 0x00,	NULL, HFILL } },
		{&hf_t38_fragment,
			{"Message fragment", "t38.fragment",
			FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
		{&hf_t38_fragment_overlap,
			{"Message fragment overlap", "t38.fragment.overlap",
			FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
		{&hf_t38_fragment_overlap_conflicts,
			{"Message fragment overlapping with conflicting data",
			"t38.fragment.overlap.conflicts",
			FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
		{&hf_t38_fragment_multiple_tails,
			{"Message has multiple tail fragments",
			"t38.fragment.multiple_tails",
			FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
		{&hf_t38_fragment_too_long_fragment,
			{"Message fragment too long", "t38.fragment.too_long_fragment",
			FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } },
		{&hf_t38_fragment_error,
			{"Message defragmentation error", "t38.fragment.error",
			FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
		{&hf_t38_fragment_count,
			{"Message fragment count", "t38.fragment.count",
			FT_UINT32, BASE_DEC, NULL, 0x00, NULL, HFILL } },
		{&hf_t38_reassembled_in,
			{"Reassembled in", "t38.reassembled.in",
			FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL } },
		{&hf_t38_reassembled_length,
			{"Reassembled T38 length", "t38.reassembled.length",
			FT_UINT32, BASE_DEC, NULL, 0x00, NULL, HFILL } },
	};

	static int *ett[] =
	{
		&ett_t38,
    &ett_t38_IFPPacket,
    &ett_t38_Type_of_msg,
    &ett_t38_Data_Field,
    &ett_t38_Data_Field_item,
    &ett_t38_UDPTLPacket,
    &ett_t38_T_error_recovery,
    &ett_t38_T_secondary_ifp_packets,
    &ett_t38_T_fec_info,
    &ett_t38_T_fec_data,
		&ett_t38_setup,
		&ett_data_fragment,
		&ett_data_fragments
	};

	static ei_register_info ei[] = {
		{ &ei_t38_malformed, { "t38.malformed", PI_MALFORMED, PI_ERROR, "Malformed packet", EXPFILL }},
	};

	module_t *t38_module;
	expert_module_t* expert_t38;

	proto_t38 = proto_register_protocol("T.38", "T.38", "t38");
	proto_register_field_array(proto_t38, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	expert_t38 = expert_register_protocol(proto_t38);
	expert_register_field_array(expert_t38, ei, array_length(ei));
	t38_udp_handle=register_dissector("t38_udp", dissect_t38_udp, proto_t38);
	t38_tcp_handle=register_dissector("t38_tcp", dissect_t38_tcp, proto_t38);
	t38_tcp_pdu_handle=register_dissector("t38_tcp_pdu", dissect_t38_tcp_pdu, proto_t38);

	/* Register reassemble tables for HDLC */
	reassembly_table_register(&data_reassembly_table,
                              &addresses_reassembly_table_functions);

	t38_tap = register_tap("t38");

	t38_module = prefs_register_protocol(proto_t38, NULL);
	prefs_register_bool_preference(t38_module, "use_pre_corrigendum_asn1_specification",
	    "Use the Pre-Corrigendum ASN.1 specification",
	    "Whether the T.38 dissector should decode using the Pre-Corrigendum T.38 "
		"ASN.1 specification (1998).",
	    &use_pre_corrigendum_asn1_specification);
	prefs_register_bool_preference(t38_module, "dissect_possible_rtpv2_packets_as_rtp",
	    "Dissect possible RTP version 2 packets with RTP dissector",
	    "Whether a UDP packet that looks like RTP version 2 packet will "
		"be dissected as RTP packet or T.38 packet. If enabled there is a risk that T.38 UDPTL "
		"packets with sequence number higher than 32767 may be dissected as RTP.",
	    &dissect_possible_rtpv2_packets_as_rtp);
	prefs_register_bool_preference(t38_module, "reassembly",
		"Reassemble T.38 PDUs over TPKT over TCP",
		"Whether the dissector should reassemble T.38 PDUs spanning multiple TCP segments "
		"when TPKT is used over TCP. "
		"To use this option, you must also enable \"Allow subdissectors to reassemble "
		"TCP streams\" in the TCP protocol settings.",
		&t38_tpkt_reassembly);
	prefs_register_enum_preference(t38_module, "tpkt_usage",
		"TPKT used over TCP",
		"Whether T.38 is used with TPKT for TCP",
		(int *)&t38_tpkt_usage,t38_tpkt_options,false);

	prefs_register_bool_preference(t38_module, "show_setup_info",
                "Show stream setup information",
                "Where available, show which protocol and frame caused "
                "this T.38 stream to be created",
                &global_t38_show_setup_info);

}

void
proto_reg_handoff_t38(void)
{
	rtp_handle = find_dissector_add_dependency("rtp", proto_t38);
	t30_hdlc_handle = find_dissector_add_dependency("t30.hdlc", proto_t38);
	proto_acdr = proto_get_id_by_filter_name("acdr");
	data_handle = find_dissector("data");
	dissector_add_for_decode_as("tcp.port", t38_tcp_handle);
	dissector_add_for_decode_as("udp.port", t38_udp_handle);
	heur_dissector_add("udp", dissect_t38_acdr_heur, "T38 over AC DR", "t38_acdr", proto_t38, HEURISTIC_ENABLE);
	dissector_add_uint("acdr.media_type", ACDR_T38, t38_udp_handle);
}