random.c revision 285206 
1/*
2 * util/random.c - thread safe random generator, which is reasonably secure.
3 *
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 * Thread safe random functions. Similar to arc4random() with an explicit
39 * initialisation routine.
40 *
41 * The code in this file is based on arc4random from
42 * openssh-4.0p1/openbsd-compat/bsd-arc4random.c
43 * That code is also BSD licensed. Here is their statement:
44 *
45 * Copyright (c) 1996, David Mazieres <dm@uun.org>
46 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
47 *
48 * Permission to use, copy, modify, and distribute this software for any
49 * purpose with or without fee is hereby granted, provided that the above
50 * copyright notice and this permission notice appear in all copies.
51 *
52 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
53 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
54 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
55 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
56 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
57 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
58 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
59 */
60#include "config.h"
61#include "util/random.h"
62#include "util/log.h"
63#include <time.h>
64
65#ifdef HAVE_NSS
66/* nspr4 */
67#include "prerror.h"
68/* nss3 */
69#include "secport.h"
70#include "pk11pub.h"
71#endif
72
73/**
74 * Max random value.  Similar to RAND_MAX, but more portable
75 * (mingw uses only 15 bits random).
76 */
77#define MAX_VALUE 0x7fffffff
78
79#ifndef HAVE_NSS
80void
81ub_systemseed(unsigned int ATTR_UNUSED(seed))
82{
83	/* arc4random_uniform does not need seeds, it gets kernel entropy */
84}
85
86struct ub_randstate*
87ub_initstate(unsigned int ATTR_UNUSED(seed),
88	struct ub_randstate* ATTR_UNUSED(from))
89{
90	struct ub_randstate* s = (struct ub_randstate*)malloc(1);
91	if(!s) {
92		log_err("malloc failure in random init");
93		return NULL;
94	}
95	return s;
96}
97
98long int
99ub_random(struct ub_randstate* ATTR_UNUSED(s))
100{
101	/* This relies on MAX_VALUE being 0x7fffffff. */
102	return (long)arc4random() & MAX_VALUE;
103}
104
105long int
106ub_random_max(struct ub_randstate* state, long int x)
107{
108	(void)state;
109	/* on OpenBSD, this does not need _seed(), or _stir() calls */
110	return (long)arc4random_uniform((uint32_t)x);
111}
112
113#else
114
115/* not much to remember for NSS since we use its pk11_random, placeholder */
116struct ub_randstate {
117	int ready;
118};
119
120void ub_systemseed(unsigned int ATTR_UNUSED(seed))
121{
122}
123
124struct ub_randstate* ub_initstate(unsigned int ATTR_UNUSED(seed),
125	struct ub_randstate* ATTR_UNUSED(from))
126{
127	struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s));
128	if(!s) {
129		log_err("malloc failure in random init");
130		return NULL;
131	}
132	return s;
133}
134
135long int ub_random(struct ub_randstate* ATTR_UNUSED(state))
136{
137	long int x;
138	/* random 31 bit value. */
139	SECStatus s = PK11_GenerateRandom((unsigned char*)&x, (int)sizeof(x));
140	if(s != SECSuccess) {
141		log_err("PK11_GenerateRandom error: %s",
142			PORT_ErrorToString(PORT_GetError()));
143	}
144	return x & MAX_VALUE;
145}
146
147long int
148ub_random_max(struct ub_randstate* state, long int x)
149{
150	/* make sure we fetch in a range that is divisible by x. ignore
151	 * values from d .. MAX_VALUE, instead draw a new number */
152	long int d = MAX_VALUE - (MAX_VALUE % x); /* d is divisible by x */
153	long int v = ub_random(state);
154	while(d <= v)
155		v = ub_random(state);
156	return (v % x);
157}
158#endif /* HAVE_NSS */
159
160void
161ub_randfree(struct ub_randstate* s)
162{
163	if(s)
164		free(s);
165	/* user app must do RAND_cleanup(); */
166}
167