////////////////////////////////////////////////////////////////////////////////
// Copyright 2013 Google LLC.
//
// This software is licensed under the terms defined in the Widevine Master
// License Agreement. For a copy of this agreement, please contact
// widevine-licensing@google.com.
////////////////////////////////////////////////////////////////////////////////
//
// Description:
//   Functionality used to verifier ChromeOS remote attestation.

#ifndef COMMON_REMOTE_ATTESTATION_VERIFIER_H_
#define COMMON_REMOTE_ATTESTATION_VERIFIER_H_

#include <map>
#include <memory>
#include <string>

#include "base/macros.h"
#include "base/thread_annotations.h"
#include "absl/synchronization/mutex.h"
#include "common/status.h"
#include "common/x509_cert.h"
#include "protos/public/client_identification.pb.h"
#include "protos/public/remote_attestation.pb.h"

namespace widevine {

// Singleton class used to do remote attestation. Access singleton instance via
// the get() method.
// TODO(user): This class is tested as part of the Session unit tests, but
// finer unit tests should be implemented for the failure cases.
class RemoteAttestationVerifier {
 public:
  RemoteAttestationVerifier() : enable_test_certificates_(false) {}
  virtual ~RemoteAttestationVerifier() {}

  // Singleton accessor.
  static RemoteAttestationVerifier& get();

  // Call to use the test (non-production) remote attestation root certificate.
  // This method is thread-safe.
  void EnableTestDrmCertificates(bool enable);

  // Call to verify a RemoteAttestation challenge response, used in licensing
  // protocol.
  // |message| is the challenge message,
  // |remote_attestation| is the remote attestation response to verify,
  // |remote_attestation_cert_sn| is a pointer to a std::string which on successful
  // return will contain the serial number for the client's remote attestation
  // certificate.
  // This method is thread-safe.
  util::Status VerifyRemoteAttestation(
      const std::string& message, const RemoteAttestation& remote_attestation,
      std::string* remote_attestation_cert_sn);

  // Call to verify a RemoteAttestation challenge response, used in certificate
  // provisioning protocol.
  // |message| is the challenge message,
  // |remote_attestation| is the remote attestation response to verify,
  // |privacy_key| is used to decrypt the EncryptedClientIdentification within
  // the |remote_attestation| message.
  // This method is thread-safe.
  util::Status VerifyRemoteAttestation(
      const std::string& message, const RemoteAttestation& remote_attestation,
      const std::string& privacy_key);

 private:
  // Common subroutine to perform the verification.
  // |message| is the challenge message,
  // |remote_attestation| is the remote attestation response to verify,
  // |client_id| is the decrypted client identification carrying the token,
  // |remote_attestation_cert_sn| is a pointer to a std::string which on successful
  // return will contain the serial number for the client's remote attestation
  // certificate.
  util::Status VerifyRemoteAttestation(
      const std::string& message, const RemoteAttestation& remote_attestation,
      const ClientIdentification& client_id,
      std::string* remote_attestation_cert_sn);

  util::Status LoadCa();

  bool enable_test_certificates_;
  absl::Mutex ca_mutex_;
  std::unique_ptr<X509CA> ca_ GUARDED_BY(ca_mutex_);

  DISALLOW_COPY_AND_ASSIGN(RemoteAttestationVerifier);
};

}  // namespace widevine

#endif  // COMMON_REMOTE_ATTESTATION_VERIFIER_H_