unbound/compat/getentropy_win.c

   1 /*      $OpenBSD$       */
   2
   3 /*
   4  * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
   5  * Copyright (c) 2014, Bob Beck <beck@obtuse.com>
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #include <windows.h>
  21 #include <errno.h>
  22 #include <stdint.h>
  23 #include <sys/types.h>
  24 #include <wincrypt.h>
  25 #include <process.h>
  26
  27 int     getentropy(void *buf, size_t len);
  28
  29 /*
  30  * On Windows, CryptGenRandom is supposed to be a well-seeded
  31  * cryptographically strong random number generator.
  32  */
  33 int
  34 getentropy(void *buf, size_t len)
  35 {
  36         HCRYPTPROV provider;
  37
  38         if (len > 256) {
  39                 errno = EIO;
  40                 return -1;
  41         }
  42
  43         if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
  44             CRYPT_VERIFYCONTEXT) == 0)
  45                 goto fail;
  46         if (CryptGenRandom(provider, len, buf) == 0) {
  47                 CryptReleaseContext(provider, 0);
  48                 goto fail;
  49         }
  50         CryptReleaseContext(provider, 0);
  51         return (0);
  52
  53 fail:
  54         errno = EIO;
  55         return (-1);
  56 }