Add policy handling for v16

[ Merge of http://go/wvgerrit/93865 ]

This allows for handling of timer and clock values as supported when both
the license service and the OEMCrypto on the device support v16.
A flag based on a value in the SignedResponse license indicates
whether this support should be enabled. A new class PolicyTimerV16
performs the duration value evaluation.

Bug: 139372190
Test: Android WV unit/integration tests
Change-Id: Iacbbd51ad26c9f29cb5418ff832f8822982644b7

libwvdrmengine/cdm/core/include/policy_engine.h

@@ -58,7 +58,8 @@ class PolicyEngine {
   // an exact copy of the policy information stored in the license.
   // The license state transitions to kLicenseStateCanPlay if the license
   // permits playback.
-  virtual void SetLicense(const video_widevine::License& license);
+  virtual void SetLicense(const video_widevine::License& license,
+                          bool supports_core_messages);
 
   // Used to update the currently loaded entitled content keys.
   virtual void SetEntitledLicenseKeys(
@@ -66,7 +67,8 @@ class PolicyEngine {
 
   // SetLicenseForRelease is used when releasing a license. The keys in this
   // license will be ignored, and any old keys will be expired.
-  virtual void SetLicenseForRelease(const video_widevine::License& license);
+  virtual void SetLicenseForRelease(const video_widevine::License& license,
+                                    bool supports_core_messages);
 
   // Call this on first decrypt to set the start of playback.
   virtual bool BeginDecryption(void);

libwvdrmengine/cdm/core/include/policy_timers.h

@@ -28,9 +28,10 @@ class PolicyTimers {
   // SetLicense is used in handling the initial license response.
   virtual void SetLicense(const video_widevine::License& license);
 
-  // UpdateLicense is used in handling a license response for a renewal request.
-  // The response may only contain policy fields that have changed. In this
-  // case an exact copy is not what we want to happen.
+  // UpdateLicense is used in handling a license response, a renewal response,
+  // or when restoring or releasing a persistent license.
+  // In a renewal the response may only contain policy fields that have
+  // changed. In this case an exact copy is not what we want to happen.
   virtual bool UpdateLicense(int64_t current_time,
                              const video_widevine::License& license) = 0;
 

libwvdrmengine/cdm/core/include/policy_timers_v15.h

@@ -31,9 +31,15 @@ class PolicyTimersV15 : public PolicyTimers {
 
   virtual ~PolicyTimersV15() {}
 
-  // 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.
+  // UpdateLicense is used in handling a license response, a renewal response,
+  // or when restoring or releasing a persistent license.
+  // In a renewal the response may only contain policy fields that have
+  // changed. In this case an exact copy is not what we want to happen.
+  // |license_start_time_| is updated to the time mentioned in the renewal
+  // response.
+  // UpdateLicense will return false if |license_start_time| is not
+  // present or playback is not allowed due to policy or timer duration
+  // expiration.
   bool UpdateLicense(int64_t current_time,
                      const video_widevine::License& license) override;
 

libwvdrmengine/cdm/core/include/policy_timers_v16.h

@@ -0,0 +1,111 @@
+// Copyright 2020 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine Master
+// License Agreement.
+
+#ifndef WVCDM_CORE_POLICY_TIMERS_V16_H_
+#define WVCDM_CORE_POLICY_TIMERS_V16_H_
+
+#include "disallow_copy_and_assign.h"
+#include "license_protocol.pb.h"
+#include "policy_timers.h"
+#include "wv_cdm_types.h"
+
+namespace wvcdm {
+
+// OEMCrypto v16 and core messages introduced changes to how duration values
+// and clocks should be evaluated. This class provides backward compatibility
+// for licenses that do not include a core message. Durations are handled
+// in the same way as in earlier releases.
+//
+// Backward compatibility may be needed if
+//  * OEMCrypto has not been upgraded to v16
+//  * Licenses were persisted before the device was upgraded to v16
+//  * License service does not yet support core messages
+
+class PolicyTimersV16 : public PolicyTimers {
+ public:
+  PolicyTimersV16() {}
+
+  virtual ~PolicyTimersV16() {}
+
+  // UpdateLicense is used in handling a license response, a renewal response,
+  // or when restoring or releasing a persistent license.
+  // In a renewal the response may only contain policy fields that have
+  // changed. In this case an exact copy is not what we want to happen.
+  // |renewal_start_time_| is set to the time mentioned in the renewal
+  // response.
+  // UpdateLicense will return false if |license_start_time| is not
+  // present or playback is not allowed due to policy or timer duration
+  // expiration.
+  bool UpdateLicense(int64_t current_time,
+                     const video_widevine::License& license) override;
+
+  // Call this on first decrypt to set the start of playback.
+  void BeginDecryption(int64_t current_time) override;
+
+  // This is a legacy field for offline licenses. Since no grace period is
+  // supported return a default value.
+  int64_t GetGracePeriodEndTime() override { return 0; }
+
+  // For offline save and restore.
+  void RestorePlaybackTimes(int64_t current_time, int64_t playback_start_time,
+                            int64_t last_playback_time,
+                            int64_t grace_period_end_time) override;
+
+  bool HasPlaybackStarted(int64_t /* current_time */) override {
+    return playback_start_time_ != 0;
+  }
+  // For licenses that support core messages, evaluation of only rental and
+  // playback durations are needed.
+  bool HasLicenseOrRentalOrPlaybackDurationExpired(
+      int64_t current_time) override {
+    return HasRentalOrPlaybackDurationExpired(current_time);
+  }
+  bool HasPassedGracePeriod(int64_t /* current_time */) override {
+    return true;
+  }
+
+  // This returns
+  // * before playback begins: the time remaining on |rental_duration_seconds|
+  // * after playback begins:
+  //   - |soft_enforce_playback_duration| is true: the time remaining on
+  //     |playback_duration_seconds|
+  //   - |soft_enforce_playback_duration| is false: the minimum
+  //     of the time remaining on |rental_duration_seconds| or
+  //     |playback_duration_seconds|
+  //
+  // |license_duration_seconds| is ignored with the introduction of core
+  // messages
+  int64_t GetLicenseOrRentalOrPlaybackDurationRemaining(
+      int64_t current_time) override;
+  // This is only used in Query. This should return the time remaining on
+  // |rental_duration_seconds|.
+  int64_t GetLicenseOrRentalDurationRemaining(int64_t current_time) override {
+    return GetRentalDurationRemaining(current_time);
+  };
+
+ protected:
+  // Gets the clock time that the license expires based on whether we have
+  // started playing.  This takes into account GetHardLicenseExpiryTime.
+  int64_t GetExpiryTime(int64_t current_time,
+                        bool ignore_soft_enforce_playback_duration) override;
+
+  int64_t GetRenewalStartTime() override { return renewal_start_time_; }
+
+ private:
+  // Gets the clock time that the rental duration or playback will expire.
+  int64_t GetRentalExpiryTime(int64_t current_time);
+  int64_t GetPlaybackExpiryTime(int64_t current_time,
+                                bool ignore_soft_enforce_playback_duration);
+
+  bool HasRentalOrPlaybackDurationExpired(int64_t current_time);
+  int64_t GetRentalDurationRemaining(int64_t current_time);
+
+  int64_t renewal_start_time_ = 0;
+
+  CORE_DISALLOW_COPY_AND_ASSIGN(PolicyTimersV16);
+};
+
+}  // namespace wvcdm
+
+#endif  // WVCDM_CORE_POLICY_TIMERS_V16_H_

libwvdrmengine/cdm/core/include/wv_cdm_constants.h

@@ -25,6 +25,7 @@ static const size_t CERTIFICATE_DATA_SIZE = 4 * 1024;
 // Use 0 to represent never expired license as specified in EME spec
 // (NaN in JS translates to 0 in unix timestamp).
 static const int64_t NEVER_EXPIRES = 0;
+static const int64_t UNLIMITED_DURATION = 0;
 
 // This is the lower limit. For OEMCrypto v16+ one can query and find how many
 // are supported