// Copyright 2015 The BoringSSL Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H
#define OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H

#include <openssl/aes.h>
#include <openssl/ctrdrbg.h>

#include "../../bcm_support.h"
#include "../aes/internal.h"

#if defined(__cplusplus)
extern "C" {
#endif

// rand_fork_unsafe_buffering_enabled returns whether fork-unsafe buffering has
// been enabled via |RAND_enable_fork_unsafe_buffering|.
int rand_fork_unsafe_buffering_enabled(void);

// CTR_DRBG_STATE contains the state of a CTR_DRBG based on AES-256. See SP
// 800-90Ar1.
struct ctr_drbg_state_st {
  AES_KEY ks;
  block128_f block;
  ctr128_f ctr;
  uint8_t counter[16];
  uint64_t reseed_counter;
};

// CTR_DRBG_init initialises |*drbg| given |CTR_DRBG_ENTROPY_LEN| bytes of
// entropy in |entropy| and, optionally, a personalization string up to
// |CTR_DRBG_ENTROPY_LEN| bytes in length. It returns one on success and zero
// on error.
OPENSSL_EXPORT int CTR_DRBG_init(CTR_DRBG_STATE *drbg,
                                 const uint8_t entropy[CTR_DRBG_ENTROPY_LEN],
                                 const uint8_t *personalization,
                                 size_t personalization_len);

#if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM)

inline int have_rdrand(void) { return CRYPTO_is_RDRAND_capable(); }

// have_fast_rdrand returns true if RDRAND is supported and it's reasonably
// fast. Concretely the latter is defined by whether the chip is Intel (fast) or
// not (assumed slow).
inline int have_fast_rdrand(void) {
  return CRYPTO_is_RDRAND_capable() && CRYPTO_is_intel_cpu();
}

// CRYPTO_rdrand writes eight bytes of random data from the hardware RNG to
// |out|. It returns one on success or zero on hardware failure.
int CRYPTO_rdrand(uint8_t out[8]);

// CRYPTO_rdrand_multiple8_buf fills |len| bytes at |buf| with random data from
// the hardware RNG. The |len| argument must be a multiple of eight. It returns
// one on success and zero on hardware failure.
int CRYPTO_rdrand_multiple8_buf(uint8_t *buf, size_t len);

#else  // OPENSSL_X86_64 && !OPENSSL_NO_ASM

inline int have_rdrand(void) { return 0; }

inline int have_fast_rdrand(void) { return 0; }

#endif  // OPENSSL_X86_64 && !OPENSSL_NO_ASM


#if defined(__cplusplus)
}  // extern C
#endif

#endif  // OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H
