#include <stdlib.h>
#include <sys/time.h>
+#include "entropy.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");
}
+ 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;
}
}