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/*
* BIRD Internet Routing Daemon -- Random Numbers
*
* (c) 2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include "sysdep/config.h"
#include "nest/bird.h"
#ifdef HAVE_GETRANDOM
#include <sys/random.h>
#endif
u32
random_u32(void)
{
long int rand_low, rand_high;
rand_low = random();
rand_high = random();
return (rand_low & 0xffff) | ((rand_high & 0xffff) << 16);
}
/* If there is no getrandom() / getentropy(), use /dev/urandom */
#if !defined(HAVE_GETRANDOM) && !defined(HAVE_GETENTROPY)
#define HAVE_URANDOM_FD 1
static int urandom_fd = -1;
int
read_urandom_fd(void *buf, uint count)
{
if (urandom_fd < 0)
{
urandom_fd = open("/dev/urandom", O_RDONLY);
if (urandom_fd < 0)
die("Cannot open /dev/urandom: %m");
}
return read(urandom_fd, buf, count);
}
#endif
void
random_init(void)
{
uint seed;
/* Get random bytes to trip any errors early and to seed random() */
random_bytes(&seed, sizeof(seed));
srandom(seed);
}
void
random_bytes(void *buf, size_t count)
{
ASSERT(count <= 256);
while (count > 0)
{
int n = -1;
#if defined(HAVE_GETRANDOM)
n = getrandom(buf, count, 0);
#elif defined(HAVE_GETENTROPY)
n = getentropy(buf, count);
n = !n ? (int) count : n;
#elif defined(HAVE_URANDOM_FD)
n = read_urandom_fd(buf, count);
#endif
if (n < 0)
{
if (errno == EINTR)
continue;
die("Cannot get random bytes: %m");
}
buf += n;
count -= n;
}
}
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