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/*
* coap_hashkey.h -- definition of hash key type and helper functions
*
* Copyright (C) 2010-2011 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_hashkey.h
* @brief Definition of hash key type and helper functions
*/
#ifndef COAP_HASHKEY_H_
#define COAP_HASHKEY_H_
#include "libcoap.h"
#include "uthash.h"
#include "str.h"
typedef unsigned char coap_key_t[4];
#ifndef coap_hash
/**
* Calculates a fast hash over the given string @p s of length @p len and stores
* the result into @p h. Depending on the exact implementation, this function
* cannot be used as one-way function to check message integrity or simlar.
*
* @param s The string used for hash calculation.
* @param len The length of @p s.
* @param h The result buffer to store the calculated hash key.
*/
void coap_hash_impl(const unsigned char *s, size_t len, coap_key_t h);
#define coap_hash(String,Length,Result) \
coap_hash_impl((String),(Length),(Result))
/* This is used to control the pre-set hash-keys for resources. */
#define COAP_DEFAULT_HASH
#else
#undef COAP_DEFAULT_HASH
#endif /* coap_hash */
/**
* Calls coap_hash() with given @c coap_string_t object as parameter.
*
* @param Str Must contain a pointer to a coap string object.
* @param H A coap_key_t object to store the result.
*
* @hideinitializer
*/
#define coap_str_hash(Str,H) { \
assert(Str); \
memset((H), 0, sizeof(coap_key_t)); \
coap_hash((Str)->s, (Str)->length, (H)); \
}
#endif /* COAP_HASHKEY_H_ */