cc83d5197c
We only use this when we don't require the best randomness. The primary usecase for this is UUID generation, as this means we don't drain randomness from the kernel pool for them. Since UUIDs are usually not secrets RDRAND should be goot enough for them to avoid real-life collisions.
34 lines
1.3 KiB
C
34 lines
1.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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typedef enum RandomFlags {
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RANDOM_EXTEND_WITH_PSEUDO = 1 << 0, /* If we can't get enough genuine randomness, but some, fill up the rest with pseudo-randomness */
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RANDOM_BLOCK = 1 << 1, /* Rather block than return crap randomness (only if the kernel supports that) */
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RANDOM_DONT_DRAIN = 1 << 2, /* If we can't get any randomness at all, return early with -EAGAIN */
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RANDOM_ALLOW_RDRAND = 1 << 3, /* Allow usage of the CPU RNG */
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} RandomFlags;
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int genuine_random_bytes(void *p, size_t n, RandomFlags flags); /* returns "genuine" randomness, optionally filled upwith pseudo random, if not enough is available */
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void pseudo_random_bytes(void *p, size_t n); /* returns only pseudo-randommess (but possibly seeded from something better) */
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void random_bytes(void *p, size_t n); /* returns genuine randomness if cheaply available, and pseudo randomness if not. */
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void initialize_srand(void);
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static inline uint64_t random_u64(void) {
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uint64_t u;
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random_bytes(&u, sizeof(u));
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return u;
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}
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static inline uint32_t random_u32(void) {
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uint32_t u;
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random_bytes(&u, sizeof(u));
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return u;
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}
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int rdrand64(uint64_t *ret);
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