62 lines
1.0 KiB
C
62 lines
1.0 KiB
C
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#include <config.h>
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#ident "$Id$"
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#if HAVE_SYS_RANDOM_H
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#include <sys/random.h>
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#endif
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#include "bit.h"
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#include "prototypes.h"
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#include "shadowlog.h"
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/*
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* Return a uniformly-distributed CS random u_long value.
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*/
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unsigned long
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csrand(void)
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{
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FILE *fp;
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unsigned long r;
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#ifdef HAVE_GETENTROPY
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/* getentropy may exist but lack kernel support. */
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if (getentropy(&r, sizeof(r)) == 0)
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return r;
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#endif
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#ifdef HAVE_GETRANDOM
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/* Likewise getrandom. */
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if (getrandom(&r, sizeof(r), 0) == sizeof(r))
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return r;
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#endif
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#ifdef HAVE_ARC4RANDOM_BUF
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/* arc4random_buf can never fail. */
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arc4random_buf(&r, sizeof(r));
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return r;
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#endif
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/* Use /dev/urandom as a last resort. */
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fp = fopen("/dev/urandom", "r");
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if (NULL == fp) {
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goto fail;
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}
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if (fread(&r, sizeof(r), 1, fp) != 1) {
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fclose(fp);
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goto fail;
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}
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fclose(fp);
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return r;
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fail:
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fprintf(log_get_logfd(), _("Unable to obtain random bytes.\n"));
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exit(1);
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}
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