1 /* prng.h -- Pseudo Random Numbers
2 *
3 * Copyright (C) 2010--2012 Olaf Bergmann <bergmann@tzi.org>
4 *
5 * This file is part of the library tinydtls. Please see
6 * README for terms of use.
7 */
8
9 /**
10 * @file prng.h
11 * @brief Pseudo Random Numbers
12 */
13
14 #ifndef _DTLS_PRNG_H_
15 #define _DTLS_PRNG_H_
16
17 #include "tinydtls.h"
18
19 /**
20 * @defgroup prng Pseudo Random Numbers
21 * @{
22 */
23
24 #ifndef WITH_CONTIKI
25 #include <stdlib.h>
26
27 /**
28 * Fills \p buf with \p len random bytes. This is the default
29 * implementation for prng(). You might want to change prng() to use
30 * a better PRNG on your specific platform.
31 */
32 static inline int
dtls_prng(unsigned char * buf,size_t len)33 dtls_prng(unsigned char *buf, size_t len) {
34 while (len--)
35 *buf++ = rand() & 0xFF;
36 return 1;
37 }
38
39 static inline void
dtls_prng_init(unsigned short seed)40 dtls_prng_init(unsigned short seed) {
41 srand(seed);
42 }
43 #else /* WITH_CONTIKI */
44 #include <string.h>
45 #include "random.h"
46
47 #ifdef HAVE_PRNG
48 static inline int
dtls_prng(unsigned char * buf,size_t len)49 dtls_prng(unsigned char *buf, size_t len)
50 {
51 return contiki_prng_impl(buf, len);
52 }
53 #else
54 /**
55 * Fills \p buf with \p len random bytes. This is the default
56 * implementation for prng(). You might want to change prng() to use
57 * a better PRNG on your specific platform.
58 */
59 static inline int
dtls_prng(unsigned char * buf,size_t len)60 dtls_prng(unsigned char *buf, size_t len) {
61 unsigned short v = random_rand();
62 while (len > sizeof(v)) {
63 memcpy(buf, &v, sizeof(v));
64 len -= sizeof(v);
65 buf += sizeof(v);
66 v = random_rand();
67 }
68
69 memcpy(buf, &v, len);
70 return 1;
71 }
72 #endif /* HAVE_PRNG */
73
74 static inline void
dtls_prng_init(unsigned short seed)75 dtls_prng_init(unsigned short seed) {
76 /* random_init() messes with the radio interface of the CC2538 and
77 * therefore must not be called after the radio has been
78 * initialized. */
79 #ifndef CONTIKI_TARGET_CC2538DK
80 random_init(seed);
81 #endif
82 }
83 #endif /* WITH_CONTIKI */
84
85 /** @} */
86
87 #endif /* _DTLS_PRNG_H_ */
88
