1 /* 2 * hashkey.h -- definition of hash key type and helper functions 3 * 4 * Copyright (C) 2010-2011 Olaf Bergmann <bergmann@tzi.org> 5 * 6 * This file is part of the CoAP library libcoap. Please see README for terms 7 * of use. 8 */ 9 10 /** 11 * @file hashkey.h 12 * @brief definition of hash key type and helper functions 13 */ 14 15 #ifndef _COAP_HASHKEY_H_ 16 #define _COAP_HASHKEY_H_ 17 18 #include "str.h" 19 20 typedef unsigned char coap_key_t[4]; 21 22 #ifndef coap_hash 23 /** 24 * Calculates a fast hash over the given string @p s of length @p len and stores 25 * the result into @p h. Depending on the exact implementation, this function 26 * cannot be used as one-way function to check message integrity or simlar. 27 * 28 * @param s The string used for hash calculation. 29 * @param len The length of @p s. 30 * @param h The result buffer to store the calculated hash key. 31 */ 32 void coap_hash_impl(const unsigned char *s, unsigned int len, coap_key_t h); 33 34 #define coap_hash(String,Length,Result) \ 35 coap_hash_impl((String),(Length),(Result)) 36 37 /* This is used to control the pre-set hash-keys for resources. */ 38 #define __COAP_DEFAULT_HASH 39 #else 40 #undef __COAP_DEFAULT_HASH 41 #endif /* coap_hash */ 42 43 /** 44 * Calls coap_hash() with given @c str object as parameter. 45 * 46 * @param Str Must contain a pointer to a coap string object. 47 * @param H A coap_key_t object to store the result. 48 * 49 * @hideinitializer 50 */ 51 #define coap_str_hash(Str,H) { \ 52 assert(Str); \ 53 memset((H), 0, sizeof(coap_key_t)); \ 54 coap_hash((Str)->s, (Str)->length, (H)); \ 55 } 56 57 #endif /* _COAP_HASHKEY_H_ */ 58
