// Copyright 2016 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.

#include <openssl/rand.h>

// IWYU pragma: begin_keep

#include "../bcm_support.h"

#include "internal.h"

// IWYU pragma: end_keep

#if defined(OPENSSL_RAND_DETERMINISTIC)

#include <string.h>

#include <openssl/chacha.h>

#include "../internal.h"

using namespace bssl;

namespace {

// g_num_calls is the number of calls to `CRYPTO_sysrand` that have occurred.

//

// This is intentionally not thread-safe. If the fuzzer mode is ever used in a

// multi-threaded program, replace this with a thread-local. (A mutex would not

// be deterministic.)

uint64_t g_num_calls = 0;

StaticMutex g_num_calls_lock;

}  // namespace

void RAND_reset_for_fuzzing() { g_num_calls = 0; }

void bssl::CRYPTO_init_sysrand() {}

void bssl::CRYPTO_sysrand(uint8_t *out, size_t requested) {

  static const uint8_t kZeroKey[32] = {0};

  g_num_calls_lock.LockWrite();

  uint64_t num_calls = g_num_calls++;

  g_num_calls_lock.UnlockWrite();

  uint8_t nonce[12];

  OPENSSL_memset(nonce, 0, sizeof(nonce));

  OPENSSL_memcpy(nonce, &num_calls, sizeof(num_calls));

  OPENSSL_memset(out, 0, requested);

  CRYPTO_chacha_20(out, out, requested, kZeroKey, nonce, 0);

}

#endif  // OPENSSL_RAND_DETERMINISTIC