// Copyright 2020 Google LLC
//
// 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 "dice/fuzz_utils.h"

#include "dice/dice.h"
#include "fuzzer/FuzzedDataProvider.h"

namespace {

std::vector<uint8_t> ConsumeRandomLengthStringAsBytesFrom(
    FuzzedDataProvider& fdp) {
  auto s = fdp.ConsumeRandomLengthString();
  return std::vector<uint8_t>(s.begin(), s.end());
}

struct FuzzedInputValues {
  static FuzzedInputValues ConsumeFrom(FuzzedDataProvider& fdp) {
    FuzzedInputValues fiv = {};
    DiceInputValues& input_values = fiv.input_values_;

    fdp.ConsumeData(&input_values.code_hash, DICE_HASH_SIZE);

    fiv.code_descriptor_ = ConsumeRandomLengthStringAsBytesFrom(fdp);
    input_values.code_descriptor = fiv.code_descriptor_.data();
    input_values.code_descriptor_size = fiv.code_descriptor_.size();

    input_values.config_type = (DiceConfigType)fdp.ConsumeIntegralInRange(0, 1);

    fdp.ConsumeData(&input_values.config_value, DICE_INLINE_CONFIG_SIZE);

    fiv.config_descriptor_ = ConsumeRandomLengthStringAsBytesFrom(fdp);
    input_values.config_descriptor = fiv.config_descriptor_.data();
    input_values.config_descriptor_size = fiv.config_descriptor_.size();

    fdp.ConsumeData(&input_values.authority_hash, DICE_HASH_SIZE);

    fiv.authority_descriptor_ = ConsumeRandomLengthStringAsBytesFrom(fdp);
    input_values.authority_descriptor = fiv.authority_descriptor_.data();
    input_values.authority_descriptor_size = fiv.authority_descriptor_.size();

    input_values.mode = (DiceMode)fdp.ConsumeIntegralInRange(0, 3);

    fdp.ConsumeData(&input_values.hidden, DICE_HIDDEN_SIZE);

    return fiv;
  }

  operator const DiceInputValues*() const { return &input_values_; }

  std::vector<uint8_t> code_descriptor_;
  std::vector<uint8_t> config_descriptor_;
  std::vector<uint8_t> authority_descriptor_;

  DiceInputValues input_values_;
};

}  // namespace

namespace dice {
namespace fuzz {

int FuzzDiceMainFlow(const DiceOps* ops, const uint8_t* data, size_t size) {
  // Exit early if there might not be enough data to fill buffers.
  if (size < 512) {
    return 0;
  }

  FuzzedDataProvider fdp(data, size);

  // Prepare the fuzzed inputs.
  auto input_values = FuzzedInputValues::ConsumeFrom(fdp);
  uint8_t current_cdi_attest[DICE_CDI_SIZE] = {};
  uint8_t current_cdi_seal[DICE_CDI_SIZE] = {};

  fdp.ConsumeData(&current_cdi_attest, sizeof(current_cdi_attest));
  fdp.ConsumeData(&current_cdi_seal, sizeof(current_cdi_seal));

  // Initialize output parameters with fuzz data in case they are wrongly being
  // read from.
  constexpr size_t kNextCdiCertificateBufferSize = 1024;
  auto next_cdi_certificate_actual_size = fdp.ConsumeIntegral<size_t>();
  uint8_t next_cdi_certificate[kNextCdiCertificateBufferSize] = {};
  uint8_t next_cdi_attest[DICE_CDI_SIZE] = {};
  uint8_t next_cdi_seal[DICE_CDI_SIZE] = {};

  fdp.ConsumeData(&next_cdi_certificate, kNextCdiCertificateBufferSize);
  fdp.ConsumeData(&next_cdi_attest, DICE_CDI_SIZE);
  fdp.ConsumeData(&next_cdi_seal, DICE_CDI_SIZE);

  // Fuzz the main flow.
  DiceMainFlow(ops, current_cdi_attest, current_cdi_seal, input_values,
               kNextCdiCertificateBufferSize, next_cdi_certificate,
               &next_cdi_certificate_actual_size, next_cdi_attest,
               next_cdi_seal);

  return 0;
}

}  // namespace fuzz
}  // namespace dice