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