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/*
* encode.h -- encoding and decoding of CoAP data types
*
* Copyright (C) 2010-2012,2023-2024 Olaf Bergmann <bergmann@tzi.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*
* This file is part of the CoAP library libcoap. Please see README for terms
* of use.
*/
/**
* @file coap_encode.h
* @brief Encoding and decoding of CoAP data types
*/
#ifndef COAP_ENCODE_H_
#define COAP_ENCODE_H_
#if (BSD >= 199103) || defined(_WIN32)
# include <string.h>
#else
# include <strings.h>
#endif
#include <stdint.h>
#ifndef HAVE_FLS
/* include this only if fls() is not available */
extern int coap_fls(unsigned int i);
#else
#define coap_fls(i) fls(i)
#endif
#ifndef HAVE_FLSLL
/* include this only if flsll() is not available */
extern int coap_flsll(long long i);
#else
#define coap_flsll(i) flsll(i)
#endif
/**
* @ingroup application_api
* @defgroup encode Encode / Decode API
* API for endoding/decoding CoAP options.
* @{
*/
/**
* Decodes multiple-length byte sequences. @p buf points to an input byte
* sequence of length @p length. Returns the up to 4 byte decoded value.
*
* @param buf The input byte sequence to decode from
* @param length The length of the input byte sequence
*
* @return The decoded value
*/
unsigned int coap_decode_var_bytes(const uint8_t *buf, size_t length);
/**
* Decodes multiple-length byte sequences. @p buf points to an input byte
* sequence of length @p length. Returns the up to 8 byte decoded value.
*
* @param buf The input byte sequence to decode from
* @param length The length of the input byte sequence
*
* @return The decoded value
*/
uint64_t coap_decode_var_bytes8(const uint8_t *buf, size_t length);
/**
* Encodes multiple-length byte sequences. @p buf points to an output buffer of
* sufficient length to store the encoded bytes. @p value is the 4 byte value
* to encode.
* Returns the number of bytes used to encode @p value or 0 on error.
*
* @param buf The output buffer to encode into
* @param length The output buffer size to encode into (must be sufficient)
* @param value The value to encode into the buffer
*
* @return The number of bytes used to encode @p value (which can be 0
* when encoding value of 0) or @c 0 on error.
*/
unsigned int coap_encode_var_safe(uint8_t *buf,
size_t length,
unsigned int value);
/**
* Encodes multiple-length byte sequences. @p buf points to an output buffer of
* sufficient length to store the encoded bytes. @p value is the 8 byte value
* to encode.
* Returns the number of bytes used to encode @p value or 0 on error.
*
* @param buf The output buffer to encode into
* @param length The output buffer size to encode into (must be sufficient)
* @param value The value to encode into the buffer
*
* @return The number of bytes used to encode @p value (which can be 0
* when encoding value of 0) or @c 0 on error.
*/
unsigned int coap_encode_var_safe8(uint8_t *buf,
size_t length,
uint64_t value);
/** @} */
/**
* @deprecated Use coap_encode_var_safe() instead.
* Provided for backward compatibility. As @p value has a
* maximum value of 0xffffffff, and buf is usually defined as an array, it
* is unsafe to continue to use this variant if buf[] is less than buf[4].
*
* For example
* char buf[1],oops;
* ..
* coap_encode_var_bytes(buf, 0xfff);
* would cause oops to get overwritten. This error can only be found by code
* inspection.
* coap_encode_var_safe(buf, sizeof(buf), 0xfff);
* would catch this error at run-time and should be used instead.
*/
COAP_STATIC_INLINE COAP_DEPRECATED int
coap_encode_var_bytes(uint8_t *buf, unsigned int value) {
return (int)coap_encode_var_safe(buf, sizeof(value), value);
}
#endif /* COAP_ENCODE_H_ */
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