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/* 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
*/
#include "config.h"
#ifdef DEBUG
#include <stdio.h>
#endif
#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;
#ifdef DEBUG
fprintf (stderr,
"dissect_wap: Starting tvb_get_uintvar at offset %d\n", offset);
#endif
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;
}
#ifdef DEBUG
fprintf(stderr,
"dissect_wap: computing: octet is %d (0x%02x), count=%d, value=%d\n",
octet, octet, counter, value);
#endif
} while (octet & 0x80);
#ifdef DEBUG
fprintf (stderr,
"dissect_wap: Leaving tvb_get_uintvar count=%d, value=%u\n",
counter, value);
#endif
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:
*/
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