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

/* packet-wtp.c
 *
 * Routines to dissect WTP component of WAP traffic.
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * WAP dissector based on original work by Ben Fowler
 * Updated by Neil Hunter <neil.hunter@energis-squared.com>
 * WTLS support by Alexandre P. Ferreira (Splice IP)
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#ifdef DEBUG
#include <stdio.h>
#endif

#include <epan/packet.h>
#include <epan/reassemble.h>
#include "packet-wap.h"
#include "packet-wtp.h"
#include "packet-wsp.h"

void proto_register_wtp(void);
void proto_reg_handoff_wtp(void);

static const true_false_string continue_truth = {
    "TPI Present" ,
    "No TPI"
};

static const true_false_string RID_truth = {
    "Re-Transmission",
    "First transmission"
};

static const true_false_string TIDNew_truth = {
    "TID is new" ,
    "TID is valid"
};

static const true_false_string tid_response_truth = {
    "Response" ,
    "Original"
};

static const true_false_string UP_truth = {
    "User Acknowledgement required" ,
    "User Acknowledgement optional"
};

static const value_string vals_wtp_pdu_type[] = {
    { 0, "Not Allowed" },
    { 1, "Invoke" },
    { 2, "Result" },
    { 3, "Ack" },
    { 4, "Abort" },
    { 5, "Segmented Invoke" },
    { 6, "Segmented Result" },
    { 7, "Negative Ack" },
    { 0, NULL }
};

static const value_string vals_transaction_trailer[] = {
    { 0, "Not last packet" },
    { 1, "Last packet of message" },
    { 2, "Last packet of group" },
    { 3, "Re-assembly not supported" },
    { 0, NULL }
};

static const value_string vals_version[] = {
    { 0, "Current" },
    { 1, "Undefined" },
    { 2, "Undefined" },
    { 3, "Undefined" },
    { 0, NULL }
};

static const value_string vals_abort_type[] = {
    { 0, "Provider" },
    { 1, "User (WSP)" },
    { 0, NULL }
};

static const value_string vals_abort_reason_provider[] = {
    { 0x00, "Unknown" },
    { 0x01, "Protocol Error" },
    { 0x02, "Invalid TID" },
    { 0x03, "Not Implemented Class 2" },
    { 0x04, "Not Implemented SAR" },
    { 0x05, "Not Implemented User Acknowledgement" },
    { 0x06, "WTP Version Zero" },
    { 0x07, "Capacity Temporarily Exceeded" },
    { 0x08, "No Response" },
    { 0x09, "Message Too Large" },
    { 0x00, NULL }
};

static const value_string vals_transaction_classes[] = {
    { 0x00, "Unreliable Invoke without Result" },
    { 0x01, "Reliable Invoke without Result" },
    { 0x02, "Reliable Invoke with Reliable Result" },
    { 0x00, NULL }
};

static const value_string vals_tpi_type[] = {
    { 0x00, "Error" },
    { 0x01, "Info" },
    { 0x02, "Option" },
    { 0x03, "Packet sequence number" },
    { 0x04, "SDU boundary" },
    { 0x05, "Frame boundary" },
    { 0x00, NULL }
};

static const value_string vals_tpi_opt[] = {
    { 0x01, "Maximum receive unit" },
    { 0x02, "Total message size" },
    { 0x03, "Delay transmission timer" },
    { 0x04, "Maximum group" },
    { 0x05, "Current TID" },
    { 0x06, "No cached TID" },
    { 0x00, NULL }
};

/* File scoped variables for the protocol and registered fields */
static int proto_wtp;

/* These fields used by fixed part of header */
static int hf_wtp_header_sub_pdu_size;
static int hf_wtp_header_flag_continue;
static int hf_wtp_header_pdu_type;
static int hf_wtp_header_flag_Trailer;
static int hf_wtp_header_flag_RID;
static int hf_wtp_header_flag_TID;
static int hf_wtp_header_flag_TID_response;

/* These fields used by Invoke packets */
static int hf_wtp_header_Inv_version;
static int hf_wtp_header_Inv_flag_TIDNew;
static int hf_wtp_header_Inv_flag_UP;
static int hf_wtp_header_Inv_Reserved;
static int hf_wtp_header_Inv_TransactionClass;

/* static int hf_wtp_header_variable_part; */
/* static int hf_wtp_data; */

static int hf_wtp_tpi_type;
static int hf_wtp_tpi_psn;
static int hf_wtp_tpi_opt;
static int hf_wtp_tpi_optval;
static int hf_wtp_tpi_info;

static int hf_wtp_header_Ack_flag_TVETOK;
static int hf_wtp_header_Abort_type;
static int hf_wtp_header_Abort_reason_provider;
static int hf_wtp_header_Abort_reason_user;
static int hf_wtp_header_sequence_number;
static int hf_wtp_header_missing_packets;
static int hf_wtp_payload;

/* These fields used when reassembling WTP fragments */
static int hf_wtp_fragments;
static int hf_wtp_fragment;
static int hf_wtp_fragment_overlap;
static int hf_wtp_fragment_overlap_conflict;
static int hf_wtp_fragment_multiple_tails;
static int hf_wtp_fragment_too_long_fragment;
static int hf_wtp_fragment_error;
static int hf_wtp_fragment_count;
static int hf_wtp_reassembled_in;
static int hf_wtp_reassembled_length;

/* Initialize the subtree pointers */
static int ett_wtp;
static int ett_wtp_sub_pdu_tree;
static int ett_header;
static int ett_tpilist;
static int ett_wsp_fragments;
static int ett_wtp_fragment;

static const fragment_items wtp_frag_items = {
    &ett_wtp_fragment,
    &ett_wsp_fragments,
    &hf_wtp_fragments,
    &hf_wtp_fragment,
    &hf_wtp_fragment_overlap,
    &hf_wtp_fragment_overlap_conflict,
    &hf_wtp_fragment_multiple_tails,
    &hf_wtp_fragment_too_long_fragment,
    &hf_wtp_fragment_error,
    &hf_wtp_fragment_count,
    &hf_wtp_reassembled_in,
    &hf_wtp_reassembled_length,
    /* Reassembled data field */
    NULL,
    "fragments"
};

/* Handle for WSP dissector */
static dissector_handle_t wsp_handle;
static dissector_handle_t wtp_fromudp_handle;

/*
 * reassembly of WSP
 */
static reassembly_table wtp_reassembly_table;

/*
 * Extract some bitfields
 */
#define pdu_type(octet)             (((octet) >> 3) & 0x0F) /* Note pdu type must not be 0x00 */
#define transaction_class(octet)    ((octet) & 0x03)    /* ......XX */
#define transmission_trailer(octet) (((octet) >> 1) & 0x01)    /* ......X. */

static char retransmission_indicator(unsigned char octet)
{
    switch (pdu_type(octet)) {
        case INVOKE:
        case RESULT:
        case ACK:
        case SEGMENTED_INVOKE:
        case SEGMENTED_RESULT:
        case NEGATIVE_ACK:
            return octet & 0x01;    /* .......X */
        default:
            return 0;
    }
}

/*
 * dissect a TPI
 */
static void
wtp_handle_tpi(proto_tree *tree, tvbuff_t *tvb)
{
    int            offset = 0;
    unsigned char  tByte;
    unsigned char  tType;
    unsigned char  tLen;
    proto_tree    *subTree = NULL;
    proto_item    *pi;

    tByte = tvb_get_uint8(tvb, offset++);
    tType = (tByte & 0x78) >> 3;
    if (tByte & 0x04)                /* Long TPI    */
        tLen = tvb_get_uint8(tvb, offset++);
    else
        tLen = tByte & 0x03;
    pi = proto_tree_add_uint(tree, hf_wtp_tpi_type,
            tvb, 0, tvb_captured_length(tvb), tType);
    subTree = proto_item_add_subtree(pi, ett_tpilist);
    switch (tType) {
        case 0x00:            /* Error*/
            /* \todo    */
            break;
        case 0x01:            /* Info    */
            /* Beware, untested case here    */
            proto_tree_add_item(subTree, hf_wtp_tpi_info,
                    tvb, offset, tLen, ENC_NA);
            break;
        case 0x02:            /* Option    */
            proto_tree_add_item(subTree, hf_wtp_tpi_opt,
                    tvb, offset++, 1, ENC_LITTLE_ENDIAN);
            proto_tree_add_item(subTree, hf_wtp_tpi_optval,
                    tvb, offset, tLen - 1, ENC_NA);
            break;
        case 0x03:            /* PSN    */
            proto_tree_add_item(subTree, hf_wtp_tpi_psn,
                    tvb, offset, 1, ENC_LITTLE_ENDIAN);
            break;
        case 0x04:            /* SDU boundary    */
            /* \todo    */
            break;
        case 0x05:            /* Frame boundary    */
            /* \todo    */
            break;
        default:
            break;
    }
}

/* Code to actually dissect the packets */
static void
// NOLINTNEXTLINE(misc-no-recursion)
dissect_wtp_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    char          *szInfo;
    int            offCur        = 0;   /* current offset from start of WTP data */
    int            returned_length, str_index = 0;

    unsigned char  b0;

    /* continuation flag */
    unsigned char  fCon;            /* Continue flag    */
    unsigned char  fRID;            /* Re-transmission indicator*/
    unsigned char  fTTR = '\0';        /* Transmission trailer    */
    unsigned       cbHeader       = 0;    /* Fixed header length    */
    unsigned       vHeader       = 0;    /* Variable header length*/
    int            abortType      = 0;

    /* Set up structures we'll need to add the protocol subtree and manage it */
    proto_item    *ti = NULL;
    proto_tree    *wtp_tree = NULL;

    char           pdut;
    char           clsTransaction = 3;
    int            numMissing = 0;        /* Number of missing packets in a negative ack */
    int            i;
    tvbuff_t      *wsp_tvb = NULL;
    uint8_t        psn = 0;        /* Packet sequence number*/
    uint16_t       TID = 0;        /* Transaction-Id    */
    int            dataOffset;
    int            dataLen;

#define SZINFO_SIZE 256
    szInfo=(char *)wmem_alloc(pinfo->pool, SZINFO_SIZE);

    b0 = tvb_get_uint8 (tvb, offCur + 0);
    /* Discover Concatenated PDUs */
    if (b0 == 0) {
        unsigned c_fieldlen = 0;        /* Length of length-field    */
        unsigned c_pdulen = 0;        /* Length of conc. PDU    */

        if (tree) {
            ti = proto_tree_add_item(tree, proto_wtp,
                    tvb, offCur, 1, ENC_NA);
            wtp_tree = proto_item_add_subtree(ti, ett_wtp_sub_pdu_tree);
            proto_item_append_text(ti, ", PDU concatenation");
        }
        offCur = 1;
        i = 1;
        while (offCur < (int) tvb_reported_length(tvb)) {
            tvbuff_t *wtp_tvb;
            /* The length of an embedded WTP PDU is coded as either:
             *    - a 7-bit value contained in one octet with highest bit == 0.
             *    - a 15-bit value contained in two octets (little endian)
             *      if the 1st octet has its highest bit == 1.
             * This means that this is NOT encoded as an uintvar-integer!!!
             */
            b0 = tvb_get_uint8(tvb, offCur + 0);
            if (b0 & 0x80) {
                c_fieldlen = 2;
                c_pdulen = ((b0 & 0x7f) << 8) | tvb_get_uint8(tvb, offCur + 1);
            } else {
                c_fieldlen = 1;
                c_pdulen = b0;
            }
            if (tree) {
                proto_tree_add_uint(wtp_tree, hf_wtp_header_sub_pdu_size,
                        tvb, offCur, c_fieldlen, c_pdulen);
            }
            if (i > 1) {
                col_append_str(pinfo->cinfo, COL_INFO, ", ");
            }
            /* Skip the length field for the WTP sub-tvb */
            wtp_tvb = tvb_new_subset_length(tvb, offCur + c_fieldlen, c_pdulen);
            // We recurse here, but we'll run out of packet before we run out of stack.
            dissect_wtp_common(wtp_tvb, pinfo, wtp_tree);
            offCur += c_fieldlen + c_pdulen;
            i++;
        }
        if (tree) {
            proto_item_append_text(ti, ", PDU count: %u", i);
        }
        return;
    }
    /* No concatenation */
    fCon = b0 & 0x80;
    fRID = retransmission_indicator(b0);
    pdut = pdu_type(b0);

#ifdef DEBUG
    proto_tree_add_debug_text(tree, "WTP packet %u: tree = %p, pdu = %s (%u) length: %u\n",
            pinfo->num, tree,
            val_to_str(pdut, vals_wtp_pdu_type, "Unknown PDU type 0x%x"),
            pdut, tvb_captured_length(tvb));
#endif

    /* Develop the string to put in the Info column */
    returned_length =  snprintf(szInfo, SZINFO_SIZE, "WTP %s",
            val_to_str(pdut, vals_wtp_pdu_type, "Unknown PDU type 0x%x"));
    str_index += MIN(returned_length, SZINFO_SIZE-str_index);

    switch (pdut) {
        case INVOKE:
            fTTR = transmission_trailer(b0);
            TID = tvb_get_ntohs(tvb, offCur + 1);
            psn = 0;
            clsTransaction = transaction_class(tvb_get_uint8(tvb, offCur + 3));
            returned_length = snprintf(&szInfo[str_index], SZINFO_SIZE-str_index,
                    " Class %d", clsTransaction);
            str_index += MIN(returned_length, SZINFO_SIZE-str_index);
            cbHeader = 4;
            break;

        case SEGMENTED_INVOKE:
        case SEGMENTED_RESULT:
            fTTR = transmission_trailer(b0);
            TID = tvb_get_ntohs(tvb, offCur + 1);
            psn = tvb_get_uint8(tvb, offCur + 3);
            if (psn != 0) {
                returned_length = snprintf(&szInfo[str_index], SZINFO_SIZE-str_index,
                        " (%u)", psn);
                str_index += MIN(returned_length, SZINFO_SIZE-str_index);
            }
            cbHeader = 4;
            break;

        case ABORT:
            cbHeader = 4;
            break;

        case RESULT:
            fTTR = transmission_trailer(b0);
            TID = tvb_get_ntohs(tvb, offCur + 1);
            psn = 0;
            cbHeader = 3;
            break;

        case ACK:
            cbHeader = 3;
            break;

        case NEGATIVE_ACK:
            /* Variable number of missing packets */
            numMissing = tvb_get_uint8(tvb, offCur + 3);
            cbHeader = numMissing + 4;
            break;

        default:
            break;
    };
    if (fRID) {
        /*returned_length =*/ snprintf(&szInfo[str_index], SZINFO_SIZE-str_index, " R" );
        /*str_index += MIN(returned_length, SZINFO_SIZE-str_index);*/
    };
    /* In the interest of speed, if "tree" is NULL, don't do any work not
       necessary to generate protocol tree items. */
    if (tree) {
#ifdef DEBUG
        fprintf(stderr, "dissect_wtp: cbHeader = %d\n", cbHeader);
#endif
        /* NOTE - Length will be set when we process the TPI */
        ti = proto_tree_add_item(tree, proto_wtp, tvb, offCur, -1, ENC_NA);
#ifdef DEBUG
        fprintf(stderr, "dissect_wtp: (7) Returned from proto_tree_add_item\n");
#endif
        wtp_tree = proto_item_add_subtree(ti, ett_wtp);

        /* Code to process the packet goes here */
#ifdef DEBUG
        fprintf(stderr, "dissect_wtp: cbHeader = %d\n", cbHeader);
        fprintf(stderr, "dissect_wtp: offCur = %d\n", offCur);
#endif
        /* Add common items: only CON and PDU Type */
        proto_tree_add_item(
                wtp_tree,             /* tree */
                hf_wtp_header_flag_continue,     /* id */
                tvb,
                offCur,             /* start of highlight */
                1,                /* length of highlight*/
                b0                /* value */
                );
        proto_tree_add_item(wtp_tree, hf_wtp_header_pdu_type, tvb, offCur, 1, ENC_LITTLE_ENDIAN);

        switch(pdut) {
            case INVOKE:
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_Trailer, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);

                proto_tree_add_item(wtp_tree, hf_wtp_header_Inv_version , tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_Inv_flag_TIDNew, tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_Inv_flag_UP, tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_Inv_Reserved, tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_Inv_TransactionClass, tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_item_append_text(ti,
                        ", PDU: Invoke (%u)"
                        ", Transaction Class: %s (%u)",
                        INVOKE,
                        val_to_str_const(clsTransaction, vals_transaction_classes, "Undefined"),
                        clsTransaction);
                break;

            case RESULT:
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_Trailer, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_item_append_text(ti, ", PDU: Result (%u)", RESULT);
                break;

            case ACK:
                proto_tree_add_item(wtp_tree, hf_wtp_header_Ack_flag_TVETOK, tvb, offCur, 1, ENC_BIG_ENDIAN);

                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_item_append_text(ti, ", PDU: ACK (%u)", ACK);
                break;

            case ABORT:
                abortType = tvb_get_uint8 (tvb, offCur) & 0x07;
                proto_tree_add_item(wtp_tree, hf_wtp_header_Abort_type , tvb, offCur , 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);

                if (abortType == PROVIDER) {
                    uint8_t reason = tvb_get_uint8(tvb, offCur + 3);
                    proto_tree_add_item( wtp_tree, hf_wtp_header_Abort_reason_provider , tvb, offCur + 3 , 1, ENC_LITTLE_ENDIAN);
                    proto_item_append_text(ti,
                            ", PDU: Abort (%u)"
                            ", Type: Provider (%u)"
                            ", Reason: %s (%u)",
                            ABORT,
                            PROVIDER,
                            val_to_str_const(reason, vals_abort_reason_provider, "Undefined"),
                            reason);
                }
                else if (abortType == USER) {
                    uint8_t reason = tvb_get_uint8(tvb, offCur + 3);
                    proto_tree_add_item(wtp_tree, hf_wtp_header_Abort_reason_user , tvb, offCur + 3 , 1, ENC_LITTLE_ENDIAN);
                    proto_item_append_text(ti,
                            ", PDU: Abort (%u)"
                            ", Type: User (%u)"
                            ", Reason: %s (%u)",
                            ABORT,
                            PROVIDER,
                            val_to_str_ext_const(reason, &vals_wsp_reason_codes_ext, "Undefined"),
                            reason);
                }
                break;

            case SEGMENTED_INVOKE:
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_Trailer, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);

                proto_tree_add_item(wtp_tree, hf_wtp_header_sequence_number , tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_item_append_text(ti,
                        ", PDU: Segmented Invoke (%u)"
                        ", Packet Sequence Number: %u",
                        SEGMENTED_INVOKE, psn);
                break;

            case SEGMENTED_RESULT:
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_Trailer, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);

                proto_tree_add_item(wtp_tree, hf_wtp_header_sequence_number , tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                proto_item_append_text(ti,
                        ", PDU: Segmented Result (%u)"
                        ", Packet Sequence Number: %u",
                        SEGMENTED_RESULT, psn);
                break;

            case NEGATIVE_ACK:
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_RID, tvb, offCur, 1, ENC_LITTLE_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID_response, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);
                proto_tree_add_item(wtp_tree, hf_wtp_header_flag_TID, tvb, offCur + 1, 2, ENC_BIG_ENDIAN);

                proto_tree_add_item(wtp_tree, hf_wtp_header_missing_packets , tvb, offCur + 3, 1, ENC_LITTLE_ENDIAN);
                /* Iterate through missing packets */
                for (i = 0; i < numMissing; i++)
                {
                    proto_tree_add_item(wtp_tree, hf_wtp_header_sequence_number, tvb, offCur + 4 + i, 1, ENC_LITTLE_ENDIAN);
                }
                proto_item_append_text(ti,
                        ", PDU: Negative Ack (%u)"
                        ", Missing Packets: %u",
                        NEGATIVE_ACK, numMissing);
                break;

            default:
                break;
        };
        if (fRID) {
            proto_item_append_text(ti, ", Retransmission");
        }
    } else { /* tree is NULL */
#ifdef DEBUG
        fprintf(stderr, "dissect_wtp: (4) tree was %p\n", tree);
#endif
    }
    /* Process the variable part */
    if (fCon) {            /* Now, analyze variable part    */
        uint8_t   tCon;
        uint8_t   tByte;
        unsigned  tpiLen;
        tvbuff_t *tmp_tvb;

        vHeader = 0;        /* Start scan all over    */

        do {
            tByte = tvb_get_uint8(tvb, offCur + cbHeader + vHeader);
            tCon = tByte & 0x80;
            if (tByte & 0x04)    /* Long TPI    */
                tpiLen = 2 + tvb_get_uint8(tvb, offCur + cbHeader + vHeader + 1);
            else
                tpiLen = 1 + (tByte & 0x03);
            if (tree)
            {
                tmp_tvb = tvb_new_subset_length(tvb, offCur + cbHeader + vHeader, tpiLen);
                wtp_handle_tpi(wtp_tree, tmp_tvb);
            }
            vHeader += tpiLen;
        } while (tCon);
    } else {
        /* There is no variable part */
    }    /* End of variable part of header */

    /* Set the length of the WTP protocol part now we know the length of the
     * fixed and variable WTP headers */
    if (tree)
        proto_item_set_len(ti, cbHeader + vHeader);

#ifdef DEBUG
    fprintf( stderr, "dissect_wtp: cbHeader = %d\n", cbHeader );
#endif

    /*
     * Any remaining data ought to be WSP data (if not WTP ACK, NACK
     * or ABORT pdu), so, if we have any remaining data, and it's
     * not an ACK, NACK, or ABORT PDU, hand it off (defragmented) to the
     * WSP dissector.
     * Note that the last packet of a fragmented WTP message needn't
     * contain any data, so we allow payloadless packets to be
     * reassembled.  (XXX - does the reassembly code handle this
     * for packets other than the last packet?)
     *
     * Try calling a subdissector only if:
     *    - The WTP payload is resembled in this very packet,
     *    - The WTP payload is not fragmented across packets.
     */
    dataOffset = offCur + cbHeader + vHeader;
    dataLen = tvb_reported_length_remaining(tvb, dataOffset);
    if ((dataLen >= 0) &&
            ! ((pdut==ACK) || (pdut==NEGATIVE_ACK) || (pdut==ABORT)))
    {
        /* Try to reassemble if needed, and hand over to WSP
         * A fragmented WTP packet is either:
         *    - An INVOKE with fTTR (transmission trailer) not set,
         *    - a SEGMENTED_INVOKE,
         *    - A RESULT with fTTR (transmission trailer) not set,
         *    - a SEGMENTED_RESULT.
         */
        if ( ( (pdut == SEGMENTED_INVOKE) || (pdut == SEGMENTED_RESULT)
                    || ( ((pdut == INVOKE) || (pdut == RESULT)) && (!fTTR) )
             ) && tvb_bytes_exist(tvb, dataOffset, dataLen) )
        {
            /* Try reassembling fragments */
            fragment_head *fd_wtp = NULL;
            uint32_t reassembled_in = 0;
            bool save_fragmented = pinfo->fragmented;

            pinfo->fragmented = true;
            fd_wtp = fragment_add_seq(&wtp_reassembly_table, tvb, dataOffset,
                    pinfo, TID, NULL, psn, dataLen, !fTTR, 0);
            /* XXX - fragment_add_seq() yields NULL unless Wireshark knows
             * that the packet is part of a reassembled whole. This means
             * that fd_wtp will be NULL as long as Wireshark did not encounter
             * (and process) the packet containing the last fragment.
             * This implies that Wireshark needs two passes over the data for
             * correct reassembly. At the first pass, a capture containing
             * three fragments plus a retransmssion of the last fragment
             * will progressively show:
             *
             *        Packet 1: (Unreassembled fragment 1)
             *        Packet 2: (Unreassembled fragment 2)
             *        Packet 3: (Reassembled WTP)
             *        Packet 4: (WTP payload reassembled in packet 3)
             *
             * However at subsequent evaluation (e.g., by applying a display
             * filter) the packet summary will show:
             *
             *        Packet 1: (WTP payload reassembled in packet 3)
             *        Packet 2: (WTP payload reassembled in packet 3)
             *        Packet 3: (Reassembled WTP)
             *        Packet 4: (WTP payload reassembled in packet 3)
             *
             * This is important to know, and also affects read filters!
             */
            wsp_tvb = process_reassembled_data(tvb, dataOffset, pinfo,
                    "Reassembled WTP", fd_wtp, &wtp_frag_items,
                    NULL, wtp_tree);
#ifdef DEBUG
            proto_tree_add_debug_text(tree, "WTP: Packet %u %s -> %d: wsp_tvb = %p, fd_wtp = %p, frame = %u\n",
                    pinfo->num,
                    fd_wtp ? "Reassembled" : "Not reassembled",
                    fd_wtp ? fd_wtp->reassembled_in : -1,
                    wsp_tvb,
                    fd_wtp
                  );
#endif
            if (fd_wtp) {
                /* Reassembled */
                reassembled_in = fd_wtp->reassembled_in;
                if (pinfo->num == reassembled_in) {
                    /* Reassembled in this very packet:
                     * We can safely hand the tvb to the WSP dissector */
                    call_dissector(wsp_handle, wsp_tvb, pinfo, tree);
                } else {
                    /* Not reassembled in this packet */
                    col_append_fstr(pinfo->cinfo, COL_INFO,
                            "%s (WTP payload reassembled in packet %u)",
                            szInfo, fd_wtp->reassembled_in);

                    proto_tree_add_item(wtp_tree, hf_wtp_payload, tvb, dataOffset, -1, ENC_NA);
                }
            } else {
                /* Not reassembled yet, or not reassembled at all */
                col_append_fstr(pinfo->cinfo, COL_INFO,
                        "%s (Unreassembled fragment %u)",
                        szInfo, psn);
                proto_tree_add_item(wtp_tree, hf_wtp_payload, tvb, dataOffset, -1, ENC_NA);
            }
            /* Now reset fragmentation information in pinfo */
            pinfo->fragmented = save_fragmented;
        }
        else if ( ((pdut == INVOKE) || (pdut == RESULT)) && (fTTR) )
        {
            /* Non-fragmented payload */
            wsp_tvb = tvb_new_subset_remaining(tvb, dataOffset);
            /* We can safely hand the tvb to the WSP dissector */
            call_dissector(wsp_handle, wsp_tvb, pinfo, tree);
        }
        else
        {
            /* Nothing to hand to subdissector */
            col_append_str(pinfo->cinfo, COL_INFO, szInfo);
        }
    }
    else
    {
        /* Nothing to hand to subdissector */
        col_append_str(pinfo->cinfo, COL_INFO, szInfo);
    }
}

/*
 * Called directly from UDP.
 * Put "WTP+WSP" into the "Protocol" column.
 */
static int
dissect_wtp_fromudp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "WTP+WSP");
    col_clear(pinfo->cinfo, COL_INFO);

    dissect_wtp_common(tvb, pinfo, tree);
    return tvb_captured_length(tvb);
}

/*
 * Called from a higher-level WAP dissector, presumably WTLS.
 * Put "WTLS+WSP+WTP" to the "Protocol" column.
 *
 * XXX - is this supposed to be called from WTLS?  If so, we're not
 * calling it....
 *
 * XXX - can this be called from any other dissector?
 */
static int
dissect_wtp_fromwtls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "WTLS+WTP+WSP");
    col_clear(pinfo->cinfo, COL_INFO);

    dissect_wtp_common(tvb, pinfo, tree);
    return tvb_captured_length(tvb);
}

/* Register the protocol with Wireshark */
void
proto_register_wtp(void)
{

    /* Setup list of header fields */
    static hf_register_info hf[] = {
        { &hf_wtp_header_sub_pdu_size,
            { "Sub PDU size", "wtp.sub_pdu_size",
                FT_UINT16, BASE_DEC, NULL, 0x0,
                "Size of Sub-PDU (bytes)", HFILL
            }
        },
        { &hf_wtp_header_flag_continue,
            { "Continue Flag", "wtp.continue_flag",
                FT_BOOLEAN, 8, TFS( &continue_truth ), 0x80,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_pdu_type,
            { "PDU Type", "wtp.pdu_type",
                FT_UINT8, BASE_HEX, VALS( vals_wtp_pdu_type ), 0x78,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_flag_Trailer,
            { "Trailer Flags", "wtp.trailer_flags",
                FT_UINT8, BASE_HEX, VALS( vals_transaction_trailer ), 0x06,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_flag_RID,
            { "Re-transmission Indicator", "wtp.RID",
                FT_BOOLEAN, 8, TFS( &RID_truth ), 0x01,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_flag_TID_response,
            { "TID Response", "wtp.TID.response",
                FT_BOOLEAN, 16, TFS( &tid_response_truth ), 0x8000,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_flag_TID,
            { "Transaction ID", "wtp.TID",
                FT_UINT16, BASE_HEX, NULL, 0x7FFF,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Inv_version,
            { "Version", "wtp.header.version",
                FT_UINT8, BASE_HEX, VALS( vals_version ), 0xC0,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Inv_flag_TIDNew,
            { "TIDNew", "wtp.header.TIDNew",
                FT_BOOLEAN, 8, TFS( &TIDNew_truth ), 0x20,
                NULL, HFILL
        }
        },
        { &hf_wtp_header_Inv_flag_UP,
            { "U/P flag", "wtp.header.UP",
                FT_BOOLEAN, 8, TFS( &UP_truth ), 0x10,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Inv_Reserved,
            { "Reserved", "wtp.inv.reserved",
                FT_UINT8, BASE_HEX, NULL, 0x0C,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Inv_TransactionClass,
            { "Transaction Class", "wtp.inv.transaction_class",
                FT_UINT8, BASE_HEX, VALS( vals_transaction_classes ), 0x03,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Ack_flag_TVETOK,
            { "Tve/Tok flag", "wtp.ack.tvetok",
                FT_BOOLEAN, 8, NULL, 0x04,
                NULL, HFILL
            }
    },
        { &hf_wtp_header_Abort_type,
            { "Abort Type", "wtp.abort.type",
                FT_UINT8, BASE_HEX, VALS ( vals_abort_type ), 0x07,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_Abort_reason_provider,
            { "Abort Reason", "wtp.abort.reason.provider",
                FT_UINT8, BASE_HEX, VALS ( vals_abort_reason_provider ), 0x00,
                NULL, HFILL
            }
        },
        /* Assume WSP is the user and use its reason codes */
        { &hf_wtp_header_Abort_reason_user,
            { "Abort Reason", "wtp.abort.reason.user",
                FT_UINT8, BASE_HEX|BASE_EXT_STRING, &vals_wsp_reason_codes_ext, 0x00,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_sequence_number,
            { "Packet Sequence Number", "wtp.header.sequence",
                FT_UINT8, BASE_DEC, NULL, 0x00,
                NULL, HFILL
            }
        },
        { &hf_wtp_header_missing_packets,
            { "Missing Packets", "wtp.header.missing_packets",
                FT_UINT8, BASE_DEC, NULL, 0x00,
                NULL, HFILL
            }
        },
        { &hf_wtp_payload,
            { "Payload", "wtp.payload",
                FT_BYTES, BASE_NONE, NULL, 0x00,
                NULL, HFILL
            }
        },
#if 0
        { &hf_wtp_header_variable_part,
            { "Header: Variable part", "wtp.header_variable_part",
                FT_BYTES, BASE_NONE, NULL, 0x0,
                "Variable part of the header", HFILL
            }
        },
        { &hf_wtp_data,
            { "Data", "wtp.header_data",
                FT_BYTES, BASE_NONE, NULL, 0x0,
                NULL, HFILL
            }
        },
#endif
        { &hf_wtp_tpi_type,
            { "TPI", "wtp.tpi",
                FT_UINT8, BASE_HEX, VALS(vals_tpi_type), 0x00,
                "Identification of the Transport Information Item", HFILL
            }
        },
        { &hf_wtp_tpi_psn,
            { "Packet sequence number", "wtp.tpi.psn",
                FT_UINT8, BASE_DEC, NULL, 0x00,
                "Sequence number of this packet", HFILL
        }
        },
        { &hf_wtp_tpi_opt,
            { "Option", "wtp.tpi.opt",
                FT_UINT8, BASE_HEX, VALS(vals_tpi_opt), 0x00,
                "The given option for this TPI", HFILL
            }
        },
        { &hf_wtp_tpi_optval,
            { "Option Value", "wtp.tpi.opt.val",
                FT_NONE, BASE_NONE, NULL, 0x00,
                "The value that is supplied with this option", HFILL
            }
        },
        { &hf_wtp_tpi_info,
            { "Information", "wtp.tpi.info",
                FT_NONE, BASE_NONE, NULL, 0x00,
                "The information being send by this TPI", HFILL
            }
        },

        /* Fragment fields */
        { &hf_wtp_fragment_overlap,
            { "Fragment overlap", "wtp.fragment.overlap",
                FT_BOOLEAN, BASE_NONE, NULL, 0x0,
                "Fragment overlaps with other fragments", HFILL
            }
        },
        { &hf_wtp_fragment_overlap_conflict,
            { "Conflicting data in fragment overlap", "wtp.fragment.overlap.conflict",
                FT_BOOLEAN, BASE_NONE, NULL, 0x0,
                "Overlapping fragments contained conflicting data", HFILL
            }
        },
        { &hf_wtp_fragment_multiple_tails,
            { "Multiple tail fragments found", "wtp.fragment.multipletails",
                FT_BOOLEAN, BASE_NONE, NULL, 0x0,
                "Several tails were found when defragmenting the packet", HFILL
            }
        },
        { &hf_wtp_fragment_too_long_fragment,
            { "Fragment too long", "wtp.fragment.toolongfragment",
                FT_BOOLEAN, BASE_NONE, NULL, 0x0,
                "Fragment contained data past end of packet", HFILL
            }
        },
        { &hf_wtp_fragment_error,
            { "Defragmentation error", "wtp.fragment.error",
                FT_FRAMENUM, BASE_NONE, NULL, 0x0,
                "Defragmentation error due to illegal fragments", HFILL
            }
        },
        { &hf_wtp_fragment_count,
            { "Fragment count", "wtp.fragment.count",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                NULL, HFILL
            }
        },
        { &hf_wtp_reassembled_in,
            { "Reassembled in", "wtp.reassembled.in",
                FT_FRAMENUM, BASE_NONE, NULL, 0x0,
                "WTP fragments are reassembled in the given packet", HFILL
            }
        },
        { &hf_wtp_reassembled_length,
            { "Reassembled WTP length", "wtp.reassembled.length",
                FT_UINT32, BASE_DEC, NULL, 0x0,
                "The total length of the reassembled payload", HFILL
            }
        },
        { &hf_wtp_fragment,
            { "WTP Fragment", "wtp.fragment",
                FT_FRAMENUM, BASE_NONE, NULL, 0x0,
                NULL, HFILL
            }
        },
        { &hf_wtp_fragments,
            { "WTP Fragments", "wtp.fragments",
                FT_NONE, BASE_NONE, NULL, 0x0,
                NULL, HFILL
            }
        },
    };

    /* Setup protocol subtree array */
    static int *ett[] = {
        &ett_wtp,
        &ett_wtp_sub_pdu_tree,
        &ett_header,
        &ett_tpilist,
        &ett_wsp_fragments,
        &ett_wtp_fragment,
    };

    /* Register the protocol name and description */
    /* Abbreviated protocol name should Match IANA: https://www.iana.org/assignments/port-numbers/ */
    proto_wtp = proto_register_protocol("Wireless Transaction Protocol", "WTP", "wtp");

    /* Required calls to register the header fields and subtrees used */
    proto_register_field_array(proto_wtp, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));

    register_dissector("wtp-wtls", dissect_wtp_fromwtls, proto_wtp);
    wtp_fromudp_handle = register_dissector("wtp-udp", dissect_wtp_fromudp, proto_wtp);
    reassembly_table_register(&wtp_reassembly_table,
                          &addresses_reassembly_table_functions);
}

void
proto_reg_handoff_wtp(void)
{
    /*
     * Get a handle for the connection-oriented WSP dissector - if WTP
     * PDUs have data, it is WSP.
     */
    wsp_handle = find_dissector_add_dependency("wsp-co", proto_wtp);

    dissector_add_uint_with_preference("udp.port", UDP_PORT_WTP_WSP, wtp_fromudp_handle);
    dissector_add_uint("gsm_sms_ud.udh.port", UDP_PORT_WTP_WSP, wtp_fromudp_handle);
    dissector_add_uint("gsm_sms.udh.port", UDP_PORT_WTP_WSP, wtp_fromudp_handle);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */