/* packet-wap.c

 *

 * Utility routines for WAP dissectors

 *

 * 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

 */

#define WS_LOG_DOMAIN "packet-wap"

#include "config.h"

#include <wireshark.h>

#include <epan/packet.h>

#include "packet-wap.h"

/*

 * Accessor to retrieve variable length int as used in WAP protocol.

 * The value is encoded in the lower 7 bits. If the top bit is set, then the

 * value continues into the next byte.

 * The octetCount parameter holds the number of bytes read in order to return

 * the final value. Can be pre-initialised to start at offset+count.

 *

 * XXX This seems to be used exclusively for fetching size values. We should

 * probably rename this to wap_get_checked_size or something along those lines.

 */

#define MAX_WAP_UINTVAR (100 * 1000 * 1000) // Arbitrary. We need a large number that won't overflow a unsigned.

unsigned

tvb_get_uintvar (tvbuff_t *tvb, unsigned offset,

        unsigned *octetCount, packet_info *pinfo, expert_field *ei)

{

    unsigned value   = 0, previous_value;

    unsigned octet;

    unsigned counter = 0;

    ws_debug("Starting tvb_get_uintvar at offset %d", offset);

    do {

        octet = tvb_get_uint8 (tvb, offset+counter);

        counter++;

        previous_value = value;

        value <<= 7;  /* Value only exists in 7 of the 8 bits */

        value += (octet & 0x7F);

        if (value < previous_value || value > MAX_WAP_UINTVAR) {

            /* overflow; clamp the value at UINT_MAX */

            proto_tree_add_expert(NULL, pinfo, ei, tvb, offset, counter);

            value = MAX_WAP_UINTVAR;

            break;

        }

        ws_debug("computing: octet is %d (0x%02x), count=%d, value=%d",

                 octet, octet, counter, value);

    } while (octet & 0x80);

    ws_debug(" Leaving tvb_get_uintvar count=%d, value=%u",

            counter, value);

    if (octetCount)

        *octetCount = counter;

    return value;

}

/*

 * 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:

 */