/* Copyright 2019 Google LLC. All rights reserved. This file and proprietary
 * source code may only be used and distributed under the Widevine Master
 * License Agreement.
 */

#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <functional>
#include <memory>
#include <vector>

#include "OEMCryptoCENCCommon.h"
#include "core_message_deserialize.h"
#include "core_message_serialize.h"
#include "core_message_types.h"
#include "odk.h"
#include "odk_serialize.h"
#include "odk_structs.h"
#include "odk_structs_priv.h"

typedef std::function<void(const uint8_t*, uint8_t*, size_t, size_t)>
    roundtrip_fun;

using oemcrypto_core_message::ODK_LicenseRequest;
using oemcrypto_core_message::ODK_ProvisioningRequest;
using oemcrypto_core_message::ODK_RenewalRequest;

using oemcrypto_core_message::deserialize::CoreLicenseRequestFromMessage;
using oemcrypto_core_message::deserialize::CoreProvisioningRequestFromMessage;
using oemcrypto_core_message::deserialize::CoreRenewalRequestFromMessage;

using oemcrypto_core_message::serialize::CreateCoreLicenseResponse;
using oemcrypto_core_message::serialize::CreateCoreProvisioningResponse;
using oemcrypto_core_message::serialize::CreateCoreRenewalResponse;

// @ kdo deserialize; odk serialize
static OEMCryptoResult odk_serialize_LicenseRequest(
    const void* in, uint8_t* out, size_t* size,
    const ODK_LicenseRequest& core_license_request,
    const ODK_NonceValues* nonce_values) {
  return ODK_PrepareCoreLicenseRequest(out, SIZE_MAX, size, nonce_values);
}

static OEMCryptoResult odk_serialize_RenewalRequest(
    const void* in, uint8_t* out, size_t* size,
    const ODK_RenewalRequest& core_renewal, ODK_NonceValues* nonce_values) {
  ODK_ClockValues clock{};
  memcpy(&clock, in, sizeof(ODK_ClockValues));
  uint64_t system_time_seconds = core_renewal.playback_time_seconds;
  return ODK_PrepareCoreRenewalRequest(out, SIZE_MAX, size, nonce_values,
                                       &clock, system_time_seconds);
}

static OEMCryptoResult odk_serialize_ProvisioningRequest(
    const void* in, uint8_t* out, size_t* size,
    const ODK_ProvisioningRequest& core_provisioning,
    const ODK_NonceValues* nonce_values) {
  const std::string& device_id = core_provisioning.device_id;
  return ODK_PrepareCoreProvisioningRequest(
      out, SIZE_MAX, size, nonce_values,
      reinterpret_cast<const uint8_t*>(device_id.data()), device_id.size());
}

/**
 * Template arguments:
 * T: kdo deserialize output/odk serialize input structure
 * F: kdo deserialize function
 * G: odk serialize function
 *
 * raw bytes -> F deserialize -> struct T -> G serialize -> raw bytes
 */
template <typename T, typename F, typename G>
static roundtrip_fun kdo_odk(const F& kdo_fun, const G& odk_fun) {
  auto roundtrip = [&](const uint8_t* in, uint8_t* out, size_t size,
                       size_t clock_value_size) -> void {
    if (size <= clock_value_size) {
      return;
    }
    // Input byte array format: [Clock Values][data to parse]
    std::string input(reinterpret_cast<const char*>(in) + clock_value_size,
                      size - clock_value_size);
    T t = {};
    if (!kdo_fun(input, &t)) {
      return;
    }
    ODK_NonceValues nonce_values = {t.api_minor_version, t.api_major_version,
                                    t.nonce, t.session_id};
    OEMCryptoResult err = odk_fun(in, out, &size, t, &nonce_values);
    if (OEMCrypto_SUCCESS != err) {
      return;
    }
    assert(0 == memcmp(in + clock_value_size, out, size));
  };
  return roundtrip;
}

// @ odk deserialize; kdo serialize
namespace {
struct ODK_ParseLicense_Args {
  ODK_NonceValues nonce_values;
  uint8_t initial_license_load;
  uint8_t usage_entry_present;
  uint8_t request_hash[32];
  ODK_TimerLimits timer_limits;
  ODK_ClockValues clock_values;
};
struct ODK_ParseRenewal_Args {
  ODK_NonceValues nonce_values;
  uint64_t system_time;
  ODK_TimerLimits timer_limits;
  ODK_ClockValues clock_values;
};
struct ODK_ParseProvisioning_Args {
  ODK_NonceValues nonce_values;
  size_t device_id_length;
  uint8_t device_id[64];
};
}  // namespace

bool convert_byte_to_valid_boolean(const bool* in) {
  const int value = *reinterpret_cast<const int*>(in);
  return value != 0;
}

static OEMCryptoResult odk_deserialize_LicenseResponse(
    const uint8_t* message, size_t core_message_length,
    ODK_ParseLicense_Args* a, ODK_NonceValues* nonce_values,
    ODK_ParsedLicense* parsed_lic) {
  return ODK_ParseLicense(message, SIZE_MAX, core_message_length,
                          static_cast<bool>(a->initial_license_load),
                          static_cast<bool>(a->usage_entry_present),
                          a->request_hash, &a->timer_limits, &a->clock_values,
                          nonce_values, parsed_lic);
}

static bool kdo_serialize_LicenseResponse(const ODK_ParseLicense_Args* args,
                                          const ODK_ParsedLicense& parsed_lic,
                                          std::string* oemcrypto_core_message) {
  const auto& nonce_values = args->nonce_values;
  ODK_LicenseRequest core_request{nonce_values.api_minor_version,
                                  nonce_values.api_major_version,
                                  nonce_values.nonce, nonce_values.session_id};
  std::string core_request_sha_256(
      reinterpret_cast<const char*>(args->request_hash), 32);
  return CreateCoreLicenseResponse(
      parsed_lic, core_request, core_request_sha_256, oemcrypto_core_message);
}

static OEMCryptoResult odk_deserialize_RenewalResponse(
    const uint8_t* buf, size_t len, ODK_ParseRenewal_Args* a,
    ODK_NonceValues* nonce_values, ODK_PreparedRenewalRequest* renewal_msg) {
  /* Address Sanitizer doesn't like values other than 0 OR 1 for boolean
   * variables. Input from fuzzer can be parsed and any random bytes can be
   * assigned to boolean variables. Using the workaround to mitigate sanitizer
   * errors in fuzzer code and converting random bytes to 0 OR 1.
   * This has no negative security impact*/
  a->timer_limits.soft_enforce_playback_duration =
      convert_byte_to_valid_boolean(
          &a->timer_limits.soft_enforce_playback_duration);
  a->timer_limits.soft_enforce_rental_duration = convert_byte_to_valid_boolean(
      &a->timer_limits.soft_enforce_rental_duration);
  uint64_t timer_value = 0;
  OEMCryptoResult err =
      ODK_ParseRenewal(buf, SIZE_MAX, len, nonce_values, a->system_time,
                       &a->timer_limits, &a->clock_values, &timer_value);
  if (OEMCrypto_SUCCESS == err) {
    Message* msg = nullptr;
    AllocateMessage(&msg, message_block);
    InitMessage(msg, const_cast<uint8_t*>(buf), len);
    SetSize(msg, len);
    Unpack_ODK_PreparedRenewalRequest(msg, renewal_msg);
    assert(ValidMessage(msg));
  }
  return err;
}

static bool kdo_serialize_RenewalResponse(
    const ODK_ParseRenewal_Args* args,
    const ODK_PreparedRenewalRequest& renewal_msg,
    std::string* oemcrypto_core_message) {
  const auto& nonce_values = args->nonce_values;
  ODK_RenewalRequest core_request{
      nonce_values.api_minor_version, nonce_values.api_major_version,
      nonce_values.nonce, nonce_values.session_id, renewal_msg.playback_time};
  return CreateCoreRenewalResponse(
      core_request, args->timer_limits.initial_renewal_duration_seconds,
      oemcrypto_core_message);
}

static OEMCryptoResult odk_deserialize_ProvisioningResponse(
    const uint8_t* buf, size_t len, ODK_ParseProvisioning_Args* a,
    ODK_NonceValues* nonce_values, ODK_ParsedProvisioning* parsed_prov) {
  return ODK_ParseProvisioning(buf, SIZE_MAX, len, nonce_values, a->device_id,
                               a->device_id_length, parsed_prov);
}

static bool kdo_serialize_ProvisioningResponse(
    const ODK_ParseProvisioning_Args* args,
    const ODK_ParsedProvisioning& parsed_prov,
    std::string* oemcrypto_core_message) {
  const auto& nonce_values = args->nonce_values;
  if (args->device_id_length > sizeof(args->device_id)) {
    return false;
  }
  ODK_ProvisioningRequest core_request{
      nonce_values.api_minor_version, nonce_values.api_major_version,
      nonce_values.nonce, nonce_values.session_id,
      std::string(reinterpret_cast<const char*>(args->device_id),
                  args->device_id_length)};
  return CreateCoreProvisioningResponse(parsed_prov, core_request,
                                        oemcrypto_core_message);
}

/**
 * Template arguments:
 * A: struct holding function arguments
 * T: odk deserialize output/kdo serialize input structure
 * F: odk deserialize function
 * G: kdo serialize function
 *
 * raw bytes -> F deserialize -> struct T -> G serialize -> raw bytes
 */
template <typename A, typename T, typename F, typename G>
static roundtrip_fun odk_kdo(const F& odk_fun, const G& kdo_fun) {
  auto roundtrip = [&](const uint8_t* in, uint8_t* out, size_t size,
                       size_t args_size) -> void {
    // Input byte array format: [function arguments][data to parse]
    if (args_size > size) {
      return;
    }
    T t = {};
    const uint8_t* buf = in + args_size;
    std::shared_ptr<A> _args(new A());
    A* args = _args.get();
    memcpy(args, in, args_size);
    args->nonce_values.api_major_version = ODK_MAJOR_VERSION;
    args->nonce_values.api_minor_version = ODK_MINOR_VERSION;
    /*
     * Input random bytes from autofuzz are interpreted by this script as
     * [function args][data to parse]. Odk deserialize functions
     * expect the nonce values in function args to match with those
     * in data to parse which is not possible with random bytes.
     * We follow two pass approach.
     *
     * 1st pass - We copy random bytes into struct t and call kdo serialize
     * with function args which will create oemcrypto core message using nonce
     * from function args. Now we have a valid oemcrypto core message which is
     * formed using nonce_values from function args which acts as input bytes
     * for 2nd pass
     *
     * 2nd pass - oemcrypto core message from 1st pass guarantees that
     * nonce_values in [function args] and core message match. we call
     * odk_deserialize using nonce from function args and oemcrypto core message
     * from 1st pass. Then we call kdo function which generates oemcrypto core
     * message2, which should be equal to oemcrypto_core_message which was input
     * to 2nd pass
     */
    // TODO(ellurubharath): Use structure aware fuzzing
    // 1st pass
    memcpy(&t, buf, sizeof(t));
    std::string oemcrypto_core_message;
    if (!kdo_fun(args, t, &oemcrypto_core_message)) {
      return;
    }
    assert(oemcrypto_core_message.size() <= size);

    // 2nd pass
    ODK_NonceValues nonce_values = args->nonce_values;
    OEMCryptoResult result =
        odk_fun(reinterpret_cast<const uint8_t*>(oemcrypto_core_message.data()),
                oemcrypto_core_message.size(), args, &nonce_values, &t);
    if (result != OEMCrypto_SUCCESS) {
      return;
    }
    std::string oemcrypto_core_message2;
    if (!kdo_fun(args, t, &oemcrypto_core_message2)) {
      return;
    }
    assert(oemcrypto_core_message == oemcrypto_core_message2);
  };
  return roundtrip;
}

// @ fuzz raw -> parsed -> raw
static void verify_roundtrip(const uint8_t* in, size_t size,
                             roundtrip_fun roundtrip, size_t args_size) {
  std::vector<uint8_t> _out(size);
  auto out = _out.data();
  roundtrip(in, out, size, args_size);
}

// Entry point for fuzzer, data is random bytes program gets from autofuzzer
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  verify_roundtrip(data, size,
                   kdo_odk<ODK_LicenseRequest>(CoreLicenseRequestFromMessage,
                                               odk_serialize_LicenseRequest),
                   0);
  verify_roundtrip(data, size,
                   kdo_odk<ODK_RenewalRequest>(CoreRenewalRequestFromMessage,
                                               odk_serialize_RenewalRequest),
                   sizeof(ODK_ClockValues));
  verify_roundtrip(
      data, size,
      kdo_odk<ODK_ProvisioningRequest>(CoreProvisioningRequestFromMessage,
                                       odk_serialize_ProvisioningRequest),
      0);
  verify_roundtrip(
      data, size,
      odk_kdo<ODK_ParseLicense_Args, ODK_ParsedLicense>(
          odk_deserialize_LicenseResponse, kdo_serialize_LicenseResponse),
      sizeof(ODK_ParseLicense_Args));
  verify_roundtrip(
      data, size,
      odk_kdo<ODK_ParseRenewal_Args, ODK_PreparedRenewalRequest>(
          odk_deserialize_RenewalResponse, kdo_serialize_RenewalResponse),
      sizeof(ODK_ParseRenewal_Args));
  verify_roundtrip(data, size,
                   odk_kdo<ODK_ParseProvisioning_Args, ODK_ParsedProvisioning>(
                       odk_deserialize_ProvisioningResponse,
                       kdo_serialize_ProvisioningResponse),
                   sizeof(ODK_ParseProvisioning_Args));

  return 0;
}