| 1 | /*
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| 2 | * Copyright (c) 2009 Lukas Mejdrech
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup net
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| 30 | * @{
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| 31 | */
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| 32 |
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| 33 | /** @file
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| 34 | * General CRC and checksum computation.
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| 35 | */
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| 36 |
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| 37 | #ifndef __NET_CHECKSUM_H__
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| 38 | #define __NET_CHECKSUM_H__
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| 39 |
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| 40 | #include <byteorder.h>
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| 41 |
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| 42 | #include <sys/types.h>
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| 43 |
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| 44 | /** IP checksum value for computed zero checksum.
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| 45 | * Zero is returned as 0xFFFF (not flipped)
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| 46 | */
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| 47 | #define IP_CHECKSUM_ZERO 0xFFFFu
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| 48 |
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| 49 | /** Computes CRC32 value.
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| 50 | * @param[in] seed Initial value. Often used as 0 or ~0.
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| 51 | * @param[in] data Pointer to the beginning of data to process.
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| 52 | * @param[in] length Length of the data in bits.
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| 53 | * @returns The computed CRC32 of the length bits of the data.
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| 54 | */
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| 55 | #ifdef ARCH_IS_BIG_ENDIAN
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| 56 | #define compute_crc32( seed, data, length ) compute_crc32_be( seed, ( uint8_t * ) data, length )
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| 57 | #else
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| 58 | #define compute_crc32( seed, data, length ) compute_crc32_le( seed, ( uint8_t * ) data, length )
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| 59 | #endif
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| 60 |
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| 61 | /** Computes CRC32 value in the little-endian environment.
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| 62 | * @param[in] seed Initial value. Often used as 0 or ~0.
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| 63 | * @param[in] data Pointer to the beginning of data to process.
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| 64 | * @param[in] length Length of the data in bits.
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| 65 | * @returns The computed CRC32 of the length bits of the data.
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| 66 | */
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| 67 | uint32_t compute_crc32_le( uint32_t seed, uint8_t * data, size_t length );
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| 68 |
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| 69 | /** Computes CRC32 value in the big-endian environment.
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| 70 | * @param[in] seed Initial value. Often used as 0 or ~0.
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| 71 | * @param[in] data Pointer to the beginning of data to process.
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| 72 | * @param[in] length Length of the data in bits.
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| 73 | * @returns The computed CRC32 of the length bits of the data.
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| 74 | */
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| 75 | uint32_t compute_crc32_be( uint32_t seed, uint8_t * data, size_t length );
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| 76 |
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| 77 | /** Computes sum of the 2 byte fields.
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| 78 | * Padds one zero (0) byte if odd.
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| 79 | * @param[in] seed Initial value. Often used as 0 or ~0.
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| 80 | * @param[in] data Pointer to the beginning of data to process.
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| 81 | * @param[in] length Length of the data in bytes.
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| 82 | * @returns The computed checksum of the length bytes of the data.
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| 83 | */
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| 84 | uint32_t compute_checksum( uint32_t seed, uint8_t * data, size_t length );
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| 85 |
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| 86 | /** Compacts the computed checksum to the 16 bit number adding the carries.
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| 87 | * @param[in] sum Computed checksum.
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| 88 | * @returns Compacted computed checksum to the 16 bits.
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| 89 | */
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| 90 | uint16_t compact_checksum( uint32_t sum );
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| 91 |
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| 92 | /** Returns or flips the checksum if zero.
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| 93 | * @param[in] checksum The computed checksum.
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| 94 | * @returns The internet protocol header checksum.
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| 95 | * @returns 0xFFFF if the computed checksum is zero.
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| 96 | */
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| 97 | uint16_t flip_checksum( uint16_t checksum );
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| 98 |
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| 99 | /** Computes the ip header checksum.
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| 100 | * To compute the checksum of a new packet, the checksum header field must be zero.
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| 101 | * To check the checksum of a received packet, the checksum may be left set.
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| 102 | * The zero (0) value will be returned in this case if valid.
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| 103 | * @param[in] data The header data.
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| 104 | * @param[in] length The header length in bytes.
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| 105 | * @returns The internet protocol header checksum.
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| 106 | * @returns 0xFFFF if the computed checksum is zero.
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| 107 | */
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| 108 | uint16_t ip_checksum( uint8_t * data, size_t length );
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| 109 |
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| 110 | #endif
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| 111 |
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| 112 | /** @}
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| 113 | */
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