coap_prng.c
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/*
* coap_prng.c -- random number generation
*
* Copyright (C) 2020 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.
*/
#include "coap3/coap_internal.h"
#ifdef HAVE_GETRANDOM
#include <sys/random.h>
#else /* !HAVE_GETRANDOM */
#include <stdlib.h>
#endif /* !HAVE_GETRANDOM */
#if defined(_WIN32)
errno_t __cdecl rand_s( _Out_ unsigned int* _RandomValue );
COAP_STATIC_INLINE int
coap_prng_impl( unsigned char *buf, size_t len ) {
while ( len != 0 ) {
uint32_t r = 0;
size_t i;
if ( rand_s( &r ) != 0 )
return 0;
for ( i = 0; i < len && i < 4; i++ ) {
*buf++ = (uint8_t)r;
r >>= 8;
}
len -= i;
}
return 1;
}
#endif /* _WIN32 */
static int
coap_prng_default(void *buf, size_t len) {
#ifdef HAVE_GETRANDOM
return getrandom(buf, len, 0);
#else /* !HAVE_GETRANDOM */
#if defined(_WIN32)
return coap_prng_impl(buf,len);
#else /* !_WIN32 */
unsigned char *dst = (unsigned char *)buf;
while (len--)
*dst++ = rand() & 0xFF;
return 1;
#endif /* !_WIN32 */
#endif /* !HAVE_GETRANDOM */
}
static coap_rand_func_t rand_func = coap_prng_default;
#if defined(WITH_CONTIKI)
#elif defined(WITH_LWIP) && defined(LWIP_RAND)
#else
void
coap_set_prng(coap_rand_func_t rng) {
rand_func = rng;
}
void
coap_prng_init(unsigned int seed) {
#ifdef HAVE_GETRANDOM
/* No seed to seed the random source if getrandom() is used,
* see dtls_prng(). */
(void)seed;
#else /* !HAVE_GETRANDOM */
srand(seed);
#endif /* !HAVE_GETRANDOM */
}
int
coap_prng(void *buf, size_t len) {
if (!rand_func) {
return 0;
}
rand_func(buf, len);
return 1;
}
#endif
coap_internal.h
Pulls together all the internal only header files.
coap_prng_default
static int coap_prng_default(void *buf, size_t len)
Definition: coap_prng.c:47
rand_func
static coap_rand_func_t rand_func
Definition: coap_prng.c:62
coap_rand_func_t
int(* coap_rand_func_t)(void *out, size_t len)
Data type for random number generator function.
Definition: coap_prng.h:77
coap_set_prng
void coap_set_prng(coap_rand_func_t rng)
Replaces the current random number generation function with the default function rng.
Definition: coap_prng.c:71
coap_prng
int coap_prng(void *buf, size_t len)
Fills buf with len random bytes using the default pseudo random number generator.
Definition: coap_prng.c:87
coap_prng_init
void coap_prng_init(unsigned int seed)
Seeds the default random number generation function with the given seed.
Definition: coap_prng.c:76
COAP_STATIC_INLINE
#define COAP_STATIC_INLINE
Definition: libcoap.h:40