/* crc32-tvb.c

 * CRC-32 tvbuff routines

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 *

 * Credits:

 *

 * Table from Solomon Peachy

 * Routine from Chris Waters

 */

#include "config.h"

#include <glib.h>

#include <epan/tvbuff.h>

#include <wsutil/crc32.h>

#include <epan/crc32-tvb.h>

uint32_t

crc32_ccitt_tvb(tvbuff_t *tvb, unsigned len)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, 0, len);

  return ( crc32_ccitt_seed(buf, len, CRC32_CCITT_SEED) );

}

uint32_t

crc32_ccitt_tvb_offset(tvbuff_t *tvb, unsigned offset, unsigned len)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, offset, len);

  return ( crc32_ccitt(buf, len) );

}

uint32_t

crc32_ccitt_tvb_seed(tvbuff_t *tvb, unsigned len, uint32_t seed)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, 0, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, 0, len);

  return ( crc32_ccitt_seed(buf, len, seed) );

}

uint32_t

crc32_ccitt_tvb_offset_seed(tvbuff_t *tvb, unsigned offset, unsigned len,

          uint32_t seed)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, offset, len);

  return ( crc32_ccitt_seed(buf, len, seed) );

}

uint32_t

crc32c_tvb_offset_calculate(tvbuff_t *tvb, unsigned offset, unsigned len, uint32_t seed)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, offset, len);

  return ( crc32c_calculate(buf, len, seed) );

}

/*

 * IEEE 802.x version (Ethernet and 802.11, at least) - byte-swap

 * the result of "crc32()".

 *

 * XXX - does this mean we should fetch the Ethernet and 802.11

 * FCS with "tvb_get_letohl()" rather than "tvb_get_ntohl()",

 * or is fetching it big-endian and byte-swapping the CRC done

 * to cope with 802.x sending stuff out in reverse bit order?

 */

uint32_t

crc32_802_tvb(tvbuff_t *tvb, unsigned len)

{

  uint32_t c_crc;

  c_crc = crc32_ccitt_tvb(tvb, len);

  /* Byte reverse. */

  c_crc = GUINT32_SWAP_LE_BE(c_crc);

  return ( c_crc );

}

uint32_t

crc32_mpeg2_tvb_offset_seed(tvbuff_t *tvb, unsigned offset,

          unsigned len, uint32_t seed)

{

  const uint8_t* buf;

  tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, offset, len);

  return ( crc32_mpeg2_seed(buf, len, seed) );

}

uint32_t

crc32_mpeg2_tvb(tvbuff_t *tvb, unsigned len)

{

  return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, CRC32_MPEG2_SEED) );

}

uint32_t

crc32_mpeg2_tvb_offset(tvbuff_t *tvb, unsigned offset, unsigned len)

{

  return ( crc32_mpeg2_tvb_offset_seed(tvb, offset, len, CRC32_MPEG2_SEED) );

}

uint32_t

crc32_mpeg2_tvb_seed(tvbuff_t *tvb, unsigned len, uint32_t seed)

{

  return ( crc32_mpeg2_tvb_offset_seed(tvb, 0, len, seed) );

}

uint32_t crc32_0x0AA725CF_tvb_offset_seed(tvbuff_t *tvb,

           unsigned offset, unsigned len, uint32_t seed)

{

  const uint8_t *buf;

  tvb_ensure_bytes_exist(tvb, offset, len);  /* len == -1 not allowed */

  buf = tvb_get_ptr(tvb, offset, len);

  return crc32_0x0AA725CF_seed(buf, len, seed);

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 8

 * tab-width: 8

 * indent-tabs-mode: t

 * End:

 *

 * vi: set shiftwidth=8 tabstop=8 noexpandtab:

 * :indentSize=8:tabSize=8:noTabs=false:

 */