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113 lines
3.1 KiB
C
113 lines
3.1 KiB
C
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/* Libottery by Nick Mathewson.
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This software has been dedicated to the public domain under the CC0
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public domain dedication.
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To the extent possible under law, the person who associated CC0 with
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libottery has waived all copyright and related or neighboring rights
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to libottery.
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You should have received a copy of the CC0 legalcode along with this
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work in doc/cc0.txt. If not, see
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<http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#define OTTERY_INTERNAL
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#include "ottery-internal.h"
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#include "ottery.h"
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <string.h>
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#define SRC(x) OTTERY_ENTROPY_SRC_ ## x
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#define DOM(x) OTTERY_ENTROPY_DOM_ ## x
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#define FL(x) OTTERY_ENTROPY_FL_ ## x
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#include "ottery_entropy_cryptgenrandom.c"
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#include "ottery_entropy_urandom.c"
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#include "ottery_entropy_rdrand.c"
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#include "ottery_entropy_egd.c"
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/** Table of RNG functions and their properties. */
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static struct ottery_randbytes_source {
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int (*fn)(const struct ottery_entropy_config *,
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struct ottery_entropy_state *,
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uint8_t *, size_t);
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uint32_t flags;
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} RAND_SOURCES[] = {
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#ifdef ENTROPY_SOURCE_CRYPTGENRANDOM
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ENTROPY_SOURCE_CRYPTGENRANDOM,
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#endif
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#ifdef ENTROPY_SOURCE_URANDOM
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ENTROPY_SOURCE_URANDOM,
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#endif
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#ifdef ENTROPY_SOURCE_EGD
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ENTROPY_SOURCE_EGD,
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#endif
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#ifdef ENTROPY_SOURCE_RDRAND
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ENTROPY_SOURCE_RDRAND,
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#endif
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{ NULL, 0 }
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};
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size_t
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ottery_get_entropy_bufsize_(size_t n)
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{
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return n * (sizeof(RAND_SOURCES)/sizeof(RAND_SOURCES[0]) - 1);
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}
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int
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ottery_get_entropy_(const struct ottery_entropy_config *config,
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struct ottery_entropy_state *state,
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uint32_t select_sources,
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uint8_t *bytes, size_t n, size_t *buflen,
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uint32_t *flags_out)
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{
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ssize_t err = OTTERY_ERR_INIT_STRONG_RNG, last_err = 0;
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int i;
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uint32_t got = 0;
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uint8_t *next;
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const uint32_t disabled_sources = config ? config->disabled_sources : 0;
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memset(bytes, 0, *buflen);
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next = bytes;
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*flags_out = 0;
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for (i=0; RAND_SOURCES[i].fn; ++i) {
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uint32_t flags = RAND_SOURCES[i].flags;
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/* Don't use a disabled source. */
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if (0 != (flags & disabled_sources))
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continue;
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/* If some flags must be set, only use those. */
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if ((flags & select_sources) != select_sources)
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continue;
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/* If we already have input from a certain domain, we don't need more */
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if ((flags & (got & OTTERY_ENTROPY_DOM_MASK)) != 0)
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continue;
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/* If we can't write these bytes, don't try. */
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if (next + n > bytes + *buflen)
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break;
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err = RAND_SOURCES[i].fn(config, state, next, n);
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if (err == 0) {
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uint32_t flags = RAND_SOURCES[i].flags;
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if (config && (flags & config->weak_sources))
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flags &= ~OTTERY_ENTROPY_FL_STRONG;
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got |= flags;
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next += n;
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} else {
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last_err = err;
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}
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}
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/* Do not report success unless at least one source was strong. */
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if (0 == (got & OTTERY_ENTROPY_FL_STRONG))
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return last_err ? last_err : OTTERY_ERR_INIT_STRONG_RNG;
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*flags_out = got;
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*buflen = next - bytes;
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return 0;
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}
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