54 lines
1.1 KiB
C
54 lines
1.1 KiB
C
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#include <errno.h>
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#include <sys/random.h>
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#include "random.h"
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#include "util.h"
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void get_random_seed(void *buf, size_t size) {
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while (size > 0) {
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ssize_t r;
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do {
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r = getrandom(buf, size, 0);
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} while (r == -1 && errno == EINTR);
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if (r <= 0) {
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fatal_error("getrandom failed");
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}
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buf = (char *)buf + r;
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size -= r;
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}
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}
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void random_state_init(UNUSED struct random_state *state) {
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}
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// TODO: add ChaCha20-based CSPRNG, for now avoid using this other than during initialization...
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void get_random_bytes(UNUSED struct random_state *state, void *buf, size_t size) {
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get_random_seed(buf, size);
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}
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size_t get_random_size(struct random_state *state) {
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size_t size;
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get_random_bytes(state, &size, sizeof(size));
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return size;
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}
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// based on OpenBSD arc4random_uniform
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size_t get_random_size_uniform(struct random_state *state, size_t bound) {
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if (bound < 2) {
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return 0;
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}
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size_t min = -bound % bound;
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size_t r;
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do {
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r = get_random_size(state);
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} while (r < min);
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return r % bound;
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}
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