android/libwvdrmengine/cdm/core/include/policy_engine.h

// Copyright 2013 Google Inc. All Rights Reserved.

#ifndef CDM_BASE_POLICY_ENGINE_H_
#define CDM_BASE_POLICY_ENGINE_H_

#include <string>

#include "license_protocol.pb.h"
#include "wv_cdm_types.h"

namespace wvcdm {

class Clock;
class PolicyEngineTest;

// This acts as an oracle that basically says "Yes(true) you may still decrypt
// or no(false) you may not decrypt this data anymore."
class PolicyEngine {
 public:
  PolicyEngine();
  ~PolicyEngine();

  // The value returned should be taken as a hint rather than an absolute
  // status. It is computed during the last call to either SetLicense/
  // UpdateLicense/OnTimerEvent/BeginDecryption and may be out of sync
  // depending on the amount of time elapsed. The current decryption
  // status is not calculated to avoid overhead in the decryption path.
  inline bool can_decrypt()         { return can_decrypt_; }

  void OnTimerEvent(bool& event_occurred, CdmEventType& event);

  // SetLicense is used in handling the initial license response. It stores
  // an exact copy of the policy information stored in the license.
  // The license state transitions to kLicenseStateCanPlay if the license
  // permits playback.
  void SetLicense(const video_widevine_server::sdk::License& license);

  // Call this on first decrypt to set the start of playback. This is
  // for cases where usage begins not when the license is received,
  // but at the start of playback
  void BeginDecryption(void);

  // UpdateLicense is used in handling a license response for a renewal request.
  // The response may only contain any policy fields that have changed. In this
  // case an exact copy is not what we want to happen. We also will receive an
  // updated license_start_time from the server. The license will transition to
  // kLicenseStateCanPlay if the license permits playback.
  void UpdateLicense(const video_widevine_server::sdk::License& license);

  CdmResponseType Query(CdmQueryMap* key_info);

  const video_widevine_server::sdk::LicenseIdentification& license_id() {
    return license_id_;
  }

 private:
  typedef enum {
    kLicenseStateInitial,
    kLicenseStateInitialPendingUsage,
    kLicenseStateCanPlay,
    kLicenseStateNeedRenewal,
    kLicenseStateWaitingLicenseUpdate,
    kLicenseStateExpired
  } LicenseState;

  void Init(Clock* clock);

  bool IsLicenseDurationExpired(int64_t current_time);
  bool IsPlaybackDurationExpired(int64_t current_time);
  bool IsRenewalDelayExpired(int64_t current_time);
  bool IsRenewalRecoveryDurationExpired(int64_t current_time);
  bool IsRenewalRetryIntervalExpired(int64_t current_time);

  void UpdateRenewalRequest(int64_t current_time);

  LicenseState license_state_;
  bool can_decrypt_;

  // This is the current policy information for this license. This gets updated
  // as license renewals occur.
  video_widevine_server::sdk::License::Policy policy_;

  // This is the license id field from server response. This data gets passed
  // back to the server in each renewal request. When we get a renewal response
  // from the license server we will get an updated id field.
  video_widevine_server::sdk::LicenseIdentification license_id_;

  // This is the license start time that gets sent from the server in each
  // license request or renewal.
  int64_t license_start_time_;

  // This is the time at which the license was received and playback was
  // started. These times are based off the local clock in case there is a
  // discrepency between local and server time.
  int64_t license_received_time_;
  int64_t playback_start_time_;

  // This is used as a reference point for policy management. This value
  // represents an offset from license_received_time_. This is used to
  // calculate the time where renewal retries should occur.
  int64_t next_renewal_time_;
  int64_t policy_max_duration_seconds_;

  Clock* clock_;

  // For testing
  friend class PolicyEngineTest;
  PolicyEngine(Clock* clock);

  CORE_DISALLOW_COPY_AND_ASSIGN(PolicyEngine);
};

}  // wvcdm

#endif  // CDM_BASE_POLICY_ENGINE_H_