126 lines
2.6 KiB
C
126 lines
2.6 KiB
C
/*
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* General purpose random utilities
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*
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* Based on libuuid code.
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*
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* This file may be redistributed under the terms of the
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* GNU Lesser General Public License.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/time.h>
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#ifndef __HAIKU__
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#include <sys/syscall.h>
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#endif
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#include "randutils.h"
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#ifdef HAVE_TLS
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#define THREAD_LOCAL static __thread
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#else
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#define THREAD_LOCAL static
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#endif
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#if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
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#define DO_JRAND_MIX
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THREAD_LOCAL unsigned short ul_jrand_seed[3];
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#endif
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int random_get_fd(void)
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{
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int i, fd;
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struct timeval tv;
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gettimeofday(&tv, 0);
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fd = open("/dev/urandom", O_RDONLY);
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if (fd == -1)
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fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
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if (fd >= 0) {
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i = fcntl(fd, F_GETFD);
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if (i >= 0)
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fcntl(fd, F_SETFD, i | FD_CLOEXEC);
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}
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srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
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#ifdef DO_JRAND_MIX
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ul_jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
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ul_jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
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ul_jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
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#endif
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/* Crank the random number generator a few times */
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gettimeofday(&tv, 0);
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for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
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rand();
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return fd;
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}
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/*
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* Generate a stream of random nbytes into buf.
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* Use /dev/urandom if possible, and if not,
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* use glibc pseudo-random functions.
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*/
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void random_get_bytes(void *buf, size_t nbytes)
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{
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size_t i, n = nbytes;
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int fd = random_get_fd();
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int lose_counter = 0;
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unsigned char *cp = (unsigned char *) buf;
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if (fd >= 0) {
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while (n > 0) {
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ssize_t x = read(fd, cp, n);
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if (x <= 0) {
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if (lose_counter++ > 16)
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break;
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continue;
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}
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n -= x;
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cp += x;
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lose_counter = 0;
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}
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close(fd);
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}
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/*
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* We do this all the time, but this is the only source of
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* randomness if /dev/random/urandom is out to lunch.
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*/
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for (cp = buf, i = 0; i < nbytes; i++)
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*cp++ ^= (rand() >> 7) & 0xFF;
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#ifdef DO_JRAND_MIX
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{
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unsigned short tmp_seed[3];
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memcpy(tmp_seed, ul_jrand_seed, sizeof(tmp_seed));
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ul_jrand_seed[2] = ul_jrand_seed[2] ^ syscall(__NR_gettid);
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for (cp = buf, i = 0; i < nbytes; i++)
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*cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
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memcpy(ul_jrand_seed, tmp_seed,
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sizeof(ul_jrand_seed)-sizeof(unsigned short));
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}
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#endif
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return;
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}
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#ifdef TEST_PROGRAM
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int main(int argc __attribute__ ((__unused__)),
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char *argv[] __attribute__ ((__unused__)))
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{
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unsigned int v, i;
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/* generate and print 10 random numbers */
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for (i = 0; i < 10; i++) {
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random_get_bytes(&v, sizeof(v));
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printf("%d\n", v);
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}
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return EXIT_SUCCESS;
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}
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#endif /* TEST_PROGRAM */
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