/* Copyright libuv contributors. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "uv.h"
#include "internal.h"
#include <errno.h>
#include <string.h>
#include <syscall.h>
#include <unistd.h>
struct uv__sysctl_args {
int* name;
int nlen;
void* oldval;
size_t* oldlenp;
void* newval;
size_t newlen;
unsigned long unused[4];
};
int uv__random_sysctl(void* buf, size_t buflen) {
static int name[] = {1 /*CTL_KERN*/, 40 /*KERN_RANDOM*/, 6 /*RANDOM_UUID*/};
struct uv__sysctl_args args;
char uuid[16];
char* p;
char* pe;
size_t n;
p = buf;
pe = p + buflen;
while (p < pe) {
memset(&args, 0, sizeof(args));
args.name = name;
args.nlen = ARRAY_SIZE(name);
args.oldval = uuid;
args.oldlenp = &n;
n = sizeof(uuid);
/* Emits a deprecation warning with some kernels but that seems like
* an okay trade-off for the fallback of the fallback: this function is
* only called when neither getrandom(2) nor /dev/urandom are available.
* Fails with ENOSYS on kernels configured without CONFIG_SYSCTL_SYSCALL.
* At least arm64 never had a _sysctl system call and therefore doesn't
* have a SYS__sysctl define either.
*/
#ifdef SYS__sysctl
if (syscall(SYS__sysctl, &args) == -1)
return UV__ERR(errno);
#else
{
(void) &args;
return UV_ENOSYS;
}
#endif
if (n != sizeof(uuid))
return UV_EIO; /* Can't happen. */
/* uuid[] is now a type 4 UUID. Bytes 6 and 8 (counting from zero) contain
* 4 and 5 bits of entropy, respectively. For ease of use, we skip those
* and only use 14 of the 16 bytes.
*/
uuid[6] = uuid[14];
uuid[8] = uuid[15];
n = pe - p;
if (n > 14)
n = 14;
memcpy(p, uuid, n);
p += n;
}
return 0;
}