inet_csum.h
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/*
* Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup net_inet_csum Internet Checksum
* @ingroup net
* @brief Provides a function to calculate the Internet Checksum
* @{
*
* @file
* @brief Internet Checksum definitions
*
* @author Martine Lenders <mlenders@inf.fu-berlin.de>
*/
#ifndef NET_INET_CSUM_H
#define NET_INET_CSUM_H
#include <inttypes.h>
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Calculates the unnormalized Internet Checksum of @p buf, where the
* buffer provides a slice of the full checksum domain, calculated in order.
*
* @see <a href="https://tools.ietf.org/html/rfc1071">
* RFC 1071
* </a>
*
* @details The Internet Checksum is not normalized (i. e. its 1's complement
* was not taken of the result) to use it for further calculation.
* This function handles padding an odd number of bytes across the full domain.
*
* @param[in] sum An initial value for the checksum.
* @param[in] buf A buffer.
* @param[in] len Length of @p buf in byte.
* @param[in] accum_len Accumulated length of checksum domain that has already
* been checksummed.
*
* @return The unnormalized Internet Checksum of @p buf.
*/
uint16_t inet_csum_slice(uint16_t sum, const uint8_t *buf, uint16_t len, size_t accum_len);
/**
* @brief Calculates the unnormalized Internet Checksum of @p buf, where the
* buffer provides a standalone domain for the checksum.
*
* @see <a href="https://tools.ietf.org/html/rfc1071">
* RFC 1071
* </a>
*
* @details The Internet Checksum is not normalized (i. e. its 1's complement
* was not taken of the result) to use it for further calculation.
* This function, rather than inet_csum_slice(), has been used historically
* when we are not concerned with padding for an odd number of bytes.
*
*
* @param[in] sum An initial value for the checksum.
* @param[in] buf A buffer.
* @param[in] len Length of @p buf in byte.
*
* @return The unnormalized Internet Checksum of @p buf.
*/
static inline uint16_t inet_csum(uint16_t sum, const uint8_t *buf, uint16_t len) {
return inet_csum_slice(sum, buf, len, 0);
}
#ifdef __cplusplus
}
#endif
#endif /* NET_INET_CSUM_H */
/** @} */