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cjdns/crypto/random/seed/BsdKernArndSysctlRandomSeed.c
2017-01-14 00:57:12 +02:00

62 lines
1.9 KiB
C

/* vim: set expandtab ts=4 sw=4: */
/*
* You may redistribute this program and/or modify it under the terms of
* the GNU General Public License as published by the Free Software Foundation,
* either version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "crypto/random/seed/BsdKernArndSysctlRandomSeed.h"
#include "util/Identity.h"
#include "util/Bits.h"
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/sysctl.h>
/** Number of times to try each operation. */
#define MAX_TRIES 10
static int get(struct RandomSeed* randomSeed, uint64_t output[8])
{
int mib[] = { CTL_KERN, KERN_ARND };
Bits_memset(output, 0, 64);
size_t len = 64;
if (sysctl(mib, 2, output, &len, NULL, 0) == -1) {
// TOR/Libevent retry this 4 bytes at a time if it fails initially.
size_t four = 4;
int tries = 0;
union {
uint64_t longs[8];
uint32_t ints[16];
} num;
for (int i = 0; i < 16; i++) {
if (sysctl(mib, 2, &num.ints[i], &four, NULL, 0) == -1) {
return -1;
}
if (num.ints[i] == 0) {
i--;
if (++tries > MAX_TRIES) {
return -1;
}
}
}
}
return Bits_isZero(output, 64) ? -1 : 0;
}
struct RandomSeed* BsdKernArndSysctlRandomSeed_new(struct Allocator* alloc)
{
return Allocator_clone(alloc, (&(struct RandomSeed) {
.get = get,
.name = "sysctl(KERN_ARND) (BSD)"
}));
}