boringssl/crypto/rand/windows.c

/* Copyright (c) 2014, Google Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#include <openssl/rand.h>

#if defined(OPENSSL_WINDOWS)

#include <limits.h>
#include <stdlib.h>
#include <Windows.h>

/* #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036.  See the
 * "Community Additions" comment on MSDN here:
 * http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx */
#define SystemFunction036 NTAPI SystemFunction036
#include <NTSecAPI.h>
#undef SystemFunction036


void RAND_cleanup(void) {
}

int RAND_bytes(uint8_t *out, size_t requested) {
  while (requested > 0) {
    ULONG output_bytes_this_pass = ULONG_MAX;
    if (requested < output_bytes_this_pass) {
      output_bytes_this_pass = requested;
    }
    if (RtlGenRandom(out, output_bytes_this_pass) == FALSE) {
      abort();
      return 0;
    }
    requested -= output_bytes_this_pass;
    out += output_bytes_this_pass;
  }
  return 1;
}

#endif  /* OPENSSL_WINDOWS */