libtommath/s_mp_rand_platform.c
2019-10-27 22:09:53 +01:00

131 lines
3.2 KiB
C

#include "tommath_private.h"
#ifdef S_MP_RAND_PLATFORM_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* First the OS-specific special cases
* - *BSD
* - Windows
*/
#if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
#define S_READ_ARC4RANDOM_C
static mp_err s_read_arc4random(void *p, size_t n)
{
arc4random_buf(p, n);
return MP_OKAY;
}
#endif
#if defined(_WIN32)
#define S_READ_WINCSP_C
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0501
#endif
#ifndef WINVER
#define WINVER 0x0501
#endif
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <wincrypt.h>
static mp_err s_read_wincsp(void *p, size_t n)
{
static HCRYPTPROV hProv = 0;
if (hProv == 0) {
HCRYPTPROV h = 0;
if (!CryptAcquireContextW(&h, NULL, MS_DEF_PROV_W, PROV_RSA_FULL,
(CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
!CryptAcquireContextW(&h, NULL, MS_DEF_PROV_W, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET)) {
return MP_ERR;
}
hProv = h;
}
return CryptGenRandom(hProv, (DWORD)n, (BYTE *)p) == TRUE ? MP_OKAY : MP_ERR;
}
#endif /* WIN32 */
#if !defined(S_READ_WINCSP_C) && defined(__linux__) && defined(__GLIBC_PREREQ)
#if __GLIBC_PREREQ(2, 25)
#define S_READ_GETRANDOM_C
#include <sys/random.h>
#include <errno.h>
static mp_err s_read_getrandom(void *p, size_t n)
{
char *q = (char *)p;
while (n > 0u) {
ssize_t ret = getrandom(q, n, 0);
if (ret < 0) {
if (errno == EINTR) {
continue;
}
return MP_ERR;
}
q += ret;
n -= (size_t)ret;
}
return MP_OKAY;
}
#endif
#endif
/* We assume all platforms besides windows provide "/dev/urandom".
* In case yours doesn't, define MP_NO_DEV_URANDOM at compile-time.
*/
#if !defined(S_READ_WINCSP_C) && !defined(MP_NO_DEV_URANDOM)
#define S_READ_URANDOM_C
#ifndef MP_DEV_URANDOM
#define MP_DEV_URANDOM "/dev/urandom"
#endif
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
static mp_err s_read_urandom(void *p, size_t n)
{
int fd;
char *q = (char *)p;
do {
fd = open(MP_DEV_URANDOM, O_RDONLY);
} while ((fd == -1) && (errno == EINTR));
if (fd == -1) return MP_ERR;
while (n > 0u) {
ssize_t ret = read(fd, p, n);
if (ret < 0) {
if (errno == EINTR) {
continue;
}
close(fd);
return MP_ERR;
}
q += ret;
n -= (size_t)ret;
}
close(fd);
return MP_OKAY;
}
#endif
mp_err s_read_arc4random(void *p, size_t n);
mp_err s_read_wincsp(void *p, size_t n);
mp_err s_read_getrandom(void *p, size_t n);
mp_err s_read_urandom(void *p, size_t n);
mp_err s_mp_rand_platform(void *p, size_t n)
{
mp_err err = MP_ERR;
if ((err != MP_OKAY) && MP_HAS(S_READ_ARC4RANDOM)) err = s_read_arc4random(p, n);
if ((err != MP_OKAY) && MP_HAS(S_READ_WINCSP)) err = s_read_wincsp(p, n);
if ((err != MP_OKAY) && MP_HAS(S_READ_GETRANDOM)) err = s_read_getrandom(p, n);
if ((err != MP_OKAY) && MP_HAS(S_READ_URANDOM)) err = s_read_urandom(p, n);
return err;
}
#endif