/*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include <config.h>
#include "random.h"
+#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/time.h>
+#include "entropy.h"
+#include "timeval.h"
#include "util.h"
/* This is the 32-bit PRNG recommended in G. Marsaglia, "Xorshift RNGs",
*
* We use this PRNG instead of libc's rand() because rand() varies in quality
* and because its maximum value also varies between 32767 and INT_MAX, whereas
- * we often want random numbers in the full range of uint32_t. */
+ * we often want random numbers in the full range of uint32_t.
+ *
+ * This random number generator is intended for purposes that do not require
+ * cryptographic-quality randomness. */
/* Current random state. */
static uint32_t seed;
void
random_init(void)
{
- if (!seed) {
+ while (!seed) {
struct timeval tv;
+ uint32_t entropy;
- if (gettimeofday(&tv, NULL) < 0) {
- ovs_fatal(errno, "gettimeofday");
- }
+ xgettimeofday(&tv);
+ get_entropy_or_die(&entropy, 4);
- seed = tv.tv_sec ^ tv.tv_usec;
- if (!seed) {
- /* A 'seed' of 0 is fatal to randomness--the random value will
- * always be 0--so use the initial seed mentioned by Marsaglia. */
- seed = UINT32_C(2463534242);
- }
+ seed = tv.tv_sec ^ tv.tv_usec ^ entropy;
}
}
+void
+random_set_seed(uint32_t seed_)
+{
+ assert(seed_);
+ seed = seed_;
+}
+
void
random_bytes(void *p_, size_t n)
{
return random_next();
}
+uint64_t
+random_uint64(void)
+{
+ uint64_t x;
+
+ random_init();
+
+ x = random_next();
+ x |= (uint64_t) random_next() << 32;
+ return x;
+}
+
int
random_range(int max)
{
random_next(void)
{
seed ^= seed << 13;
- seed >>= 17;
+ seed ^= seed >> 17;
seed ^= seed << 5;
return seed;