coap_prng.h

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/*
 * coap_prng.h -- Pseudo Random Numbers
 *
 * Copyright (C) 2010-2020 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.
 */
 
#ifndef COAP_PRNG_H_
#define COAP_PRNG_H_
 
#if defined(WITH_CONTIKI)
#include <string.h>
 
COAP_STATIC_INLINE int
contiki_prng_impl(unsigned char *buf, size_t len) {
  uint16_t v = random_rand();
  while (len > sizeof(v)) {
    memcpy(buf, &v, sizeof(v));
    len -= sizeof(v);
    buf += sizeof(v);
    v = random_rand();
  }
 
  memcpy(buf, &v, len);
  return 1;
}
 
#define coap_prng(Buf,Length) contiki_prng_impl((Buf), (Length))
#define coap_prng_init(Value) random_init((uint16_t)(Value))
 
#elif defined(WITH_LWIP) && defined(LWIP_RAND)
 
COAP_STATIC_INLINE int
lwip_prng_impl(unsigned char *buf, size_t len) {
  u32_t v = LWIP_RAND();
  while (len > sizeof(v)) {
    memcpy(buf, &v, sizeof(v));
    len -= sizeof(v);
    buf += sizeof(v);
    v = LWIP_RAND();
  }
 
  memcpy(buf, &v, len);
  return 1;
}
 
#define coap_prng(Buf,Length) lwip_prng_impl((Buf), (Length))
#define coap_prng_init(Value) (void)Value
 
#else
 
typedef int (*coap_rand_func_t)(void *out, size_t len);
 
void coap_set_prng(coap_rand_func_t rng);
 
void coap_prng_init(unsigned int seed);
 
int coap_prng(void *buf, size_t len);
 
#endif /* POSIX */
 
#endif /* COAP_PRNG_H_ */