content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * 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
   *
   *      http://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.
   */
  
  package android.media;
  
  import android.annotation.NonNull;
  import android.hardware.cas.V1_0.*;
  import android.media.MediaCasException.UnsupportedCasException;
  import android.os.IHwBinder;
  import android.os.RemoteException;
  import android.os.ServiceSpecificException;
  import android.util.Log;
  
  import java.nio.ByteBuffer;
  
  /**
   * MediaDescrambler class can be used in conjunction with {@link android.media.MediaCodec}
   * and {@link android.media.MediaExtractor} to decode media data scrambled by conditional
   * access (CA) systems such as those in the ISO/IEC13818-1.
   *
   * A MediaDescrambler object is initialized from a session opened by a MediaCas object,
   * and can be used to descramble media streams scrambled with that session's keys.
   *
   * Scrambling schemes are identified by 16-bit unsigned integer as in CA_system_id.
   *
   */
  public final class MediaDescrambler implements AutoCloseable {
      private static final String TAG = "MediaDescrambler";
      private IDescramblerBase mIDescrambler;
  
      private final void validateInternalStates() {
          if (mIDescrambler == null) {
              throw new IllegalStateException();
          }
      }
  
      private final void cleanupAndRethrowIllegalState() {
          mIDescrambler = null;
          throw new IllegalStateException();
      }
  
      /**
       * Instantiate a MediaDescrambler.
       *
       * @param CA_system_id The system id of the scrambling scheme.
       *
       * @throws UnsupportedCasException if the scrambling scheme is not supported.
       */
      public MediaDescrambler(int CA_system_id) throws UnsupportedCasException {
          try {
              mIDescrambler = MediaCas.getService().createDescrambler(CA_system_id);
          } catch(Exception e) {
              Log.e(TAG, "Failed to create descrambler: " + e);
              mIDescrambler = null;
          } finally {
              if (mIDescrambler == null) {
                  throw new UnsupportedCasException("Unsupported CA_system_id " + CA_system_id);
              }
          }
          native_setup(mIDescrambler.asBinder());
      }
  
      IHwBinder getBinder() {
          validateInternalStates();
  
          return mIDescrambler.asBinder();
      }
  
      /**
       * Query if the scrambling scheme requires the use of a secure decoder
       * to decode data of the given mime type.
       *
       * @param mime The mime type of the media data
       *
       * @throws IllegalStateException if the descrambler instance is not valid.
       */
      public final boolean requiresSecureDecoderComponent(@NonNull String mime) {
          validateInternalStates();
  
          try {
              return mIDescrambler.requiresSecureDecoderComponent(mime);
          } catch (RemoteException e) {
              cleanupAndRethrowIllegalState();
          }
          return true;
      }
  
      /**
       * Associate a MediaCas session with this MediaDescrambler instance.
       * The MediaCas session is used to securely load decryption keys for
       * the descrambler. The crypto keys loaded through the MediaCas session
       * may be selected for use during the descrambling operation performed
       * by {@link android.media.MediaExtractor or @link
       * android.media.MediaCodec#queueSecureInputBuffer} by specifying even
       * or odd key in the {@link android.media.MediaCodec.CryptoInfo#key} field.
       *
       * @param session the MediaCas session to associate with this
       * MediaDescrambler instance.
       *
       * @throws IllegalStateException if the descrambler instance is not valid.
       * @throws MediaCasStateException for CAS-specific state exceptions.
       */
      public final void setMediaCasSession(@NonNull MediaCas.Session session) {
          validateInternalStates();
  
          try {
              MediaCasStateException.throwExceptionIfNeeded(
                      mIDescrambler.setMediaCasSession(session.mSessionId));
          } catch (RemoteException e) {
              cleanupAndRethrowIllegalState();
          }
      }
  
      /**
       * Scramble control value indicating that the samples are not scrambled.
       * @see #descramble(ByteBuffer, ByteBuffer, android.media.MediaCodec.CryptoInfo)
       */
      public static final byte SCRAMBLE_CONTROL_UNSCRAMBLED = 0;
  
      /**
       * Scramble control value reserved and shouldn't be used currently.
       * @see #descramble(ByteBuffer, ByteBuffer, android.media.MediaCodec.CryptoInfo)
       */
      public static final byte SCRAMBLE_CONTROL_RESERVED    = 1;
  
      /**
       * Scramble control value indicating that the even key is used.
       * @see #descramble(ByteBuffer, ByteBuffer, android.media.MediaCodec.CryptoInfo)
       */
      public static final byte SCRAMBLE_CONTROL_EVEN_KEY     = 2;
  
      /**
       * Scramble control value indicating that the odd key is used.
       * @see #descramble(ByteBuffer, ByteBuffer, android.media.MediaCodec.CryptoInfo)
       */
      public static final byte SCRAMBLE_CONTROL_ODD_KEY      = 3;
  
      /**
       * Scramble flag for a hint indicating that the descrambling request is for
       * retrieving the PES header info only.
       *
       * @see #descramble(ByteBuffer, ByteBuffer, android.media.MediaCodec.CryptoInfo)
       */
      public static final byte SCRAMBLE_FLAG_PES_HEADER = (1 << 0);
  
      /**
       * Descramble a ByteBuffer of data described by a
       * {@link android.media.MediaCodec.CryptoInfo} structure.
       *
       * @param srcBuf ByteBuffer containing the scrambled data, which starts at
       * srcBuf.position().
       * @param dstBuf ByteBuffer to hold the descrambled data, which starts at
       * dstBuf.position().
       * @param cryptoInfo a {@link android.media.MediaCodec.CryptoInfo} structure
       * describing the subsamples contained in srcBuf. The iv and mode fields in
       * CryptoInfo are not used. key[0] contains the MPEG2TS scrambling control bits
       * (as defined in ETSI TS 100 289 (2011): "Digital Video Broadcasting (DVB);
       * Support for use of the DVB Scrambling Algorithm version 3 within digital
       * broadcasting systems"), and the value must be one of {@link #SCRAMBLE_CONTROL_UNSCRAMBLED},
       * {@link #SCRAMBLE_CONTROL_RESERVED}, {@link #SCRAMBLE_CONTROL_EVEN_KEY} or
       * {@link #SCRAMBLE_CONTROL_ODD_KEY}. key[1] is a set of bit flags, with the
       * only possible bit being {@link #SCRAMBLE_FLAG_PES_HEADER} currently.
       * key[2~15] are not used.
       *
       * @return number of bytes that have been successfully descrambled, with negative
       * values indicating errors.
       *
       * @throws IllegalStateException if the descrambler instance is not valid.
       * @throws MediaCasStateException for CAS-specific state exceptions.
       */
      public final int descramble(
              @NonNull ByteBuffer srcBuf, @NonNull ByteBuffer dstBuf,
              @NonNull MediaCodec.CryptoInfo cryptoInfo) {
          validateInternalStates();
  
          if (cryptoInfo.numSubSamples <= 0) {
              throw new IllegalArgumentException(
                      "Invalid CryptoInfo: invalid numSubSamples=" + cryptoInfo.numSubSamples);
          } else if (cryptoInfo.numBytesOfClearData == null
                  && cryptoInfo.numBytesOfEncryptedData == null) {
              throw new IllegalArgumentException(
                      "Invalid CryptoInfo: clearData and encryptedData size arrays are both null!");
          } else if (cryptoInfo.numBytesOfClearData != null
                  && cryptoInfo.numBytesOfClearData.length < cryptoInfo.numSubSamples) {
              throw new IllegalArgumentException(
                      "Invalid CryptoInfo: numBytesOfClearData is too small!");
          } else if (cryptoInfo.numBytesOfEncryptedData != null
                  && cryptoInfo.numBytesOfEncryptedData.length < cryptoInfo.numSubSamples) {
              throw new IllegalArgumentException(
                      "Invalid CryptoInfo: numBytesOfEncryptedData is too small!");
          } else if (cryptoInfo.key == null || cryptoInfo.key.length != 16) {
              throw new IllegalArgumentException(
                      "Invalid CryptoInfo: key array is invalid!");
          }
  
          try {
              return native_descramble(
                      cryptoInfo.key[0],
                      cryptoInfo.key[1],
                      cryptoInfo.numSubSamples,
                      cryptoInfo.numBytesOfClearData,
                      cryptoInfo.numBytesOfEncryptedData,
                      srcBuf, srcBuf.position(), srcBuf.limit(),
                      dstBuf, dstBuf.position(), dstBuf.limit());
          } catch (ServiceSpecificException e) {
              MediaCasStateException.throwExceptionIfNeeded(e.errorCode, e.getMessage());
          } catch (RemoteException e) {
              cleanupAndRethrowIllegalState();
          }
          return -1;
      }
  
      @Override
      public void close() {
          if (mIDescrambler != null) {
              try {
                  mIDescrambler.release();
              } catch (RemoteException e) {
              } finally {
                  mIDescrambler = null;
              }
          }
          native_release();
      }
  
      @Override
      protected void finalize() {
          close();
      }
  
      private static native final void native_init();
      private native final void native_setup(@NonNull IHwBinder decramblerBinder);
      private native final void native_release();
      private native final int native_descramble(
              byte key, byte flags, int numSubSamples,
              int[] numBytesOfClearData, int[] numBytesOfEncryptedData,
              @NonNull ByteBuffer srcBuf, int srcOffset, int srcLimit,
              ByteBuffer dstBuf, int dstOffset, int dstLimit) throws RemoteException;
  
      static {
          System.loadLibrary("media_jni");
          native_init();
      }
  
      private long mNativeContext;
  }