hardened_malloc/random.c

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C
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2018-08-21 19:23:22 +00:00
#include <errno.h>
#include <sys/random.h>
#include "random.h"
#include "util.h"
void get_random_seed(void *buf, size_t size) {
while (size > 0) {
ssize_t r;
do {
r = getrandom(buf, size, 0);
} while (r == -1 && errno == EINTR);
if (r <= 0) {
fatal_error("getrandom failed");
}
buf = (char *)buf + r;
size -= r;
}
}
void random_state_init(UNUSED struct random_state *state) {
}
// TODO: add ChaCha20-based CSPRNG, for now avoid using this other than during initialization...
void get_random_bytes(UNUSED struct random_state *state, void *buf, size_t size) {
get_random_seed(buf, size);
}
size_t get_random_size(struct random_state *state) {
size_t size;
get_random_bytes(state, &size, sizeof(size));
return size;
}
// based on OpenBSD arc4random_uniform
size_t get_random_size_uniform(struct random_state *state, size_t bound) {
if (bound < 2) {
return 0;
}
size_t min = -bound % bound;
size_t r;
do {
r = get_random_size(state);
} while (r < min);
return r % bound;
}