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#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "hash.h"
#include "random.h"
static void generate_system_random_bytes(size_t n, void *result) {
int fd;
if ((fd = open("/dev/urandom", O_RDONLY | O_NOCTTY | O_CLOEXEC)) < 0) {
err(EXIT_FAILURE, "open /dev/urandom");
}
for (;;) {
ssize_t res = read(fd, result, n);
if ((size_t) res == n) {
break;
}
if (res < 0) {
if (errno != EINTR) {
err(EXIT_FAILURE, "read /dev/urandom");
}
} else if (res == 0) {
errx(EXIT_FAILURE, "read /dev/urandom: end of file");
} else {
result = padd(result, (size_t) res);
n -= (size_t) res;
}
}
if (close(fd) < 0) {
err(EXIT_FAILURE, "close /dev/urandom");
}
}
static struct keccak_state state;
void init_random(void) {
generate_system_random_bytes(32, &state);
}
void generate_random_bytes(size_t n, void *result) {
if (n == 0) {
return;
}
for (;;) {
keccak_permutation(&state);
if (n <= HASH_DATA_AREA) {
memcpy(result, &state, n);
return;
} else {
memcpy(result, &state, HASH_DATA_AREA);
result = padd(result, HASH_DATA_AREA);
n -= HASH_DATA_AREA;
}
}
}
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