Zero out trailing bytes in CryptoInfo.iv

CryptoInfo.iv length is always 16. When the actual initialization vector
is shorter, zero out the trailing bytes.

Issue: #6982
PiperOrigin-RevId: 295575845

RELEASENOTES.md

@@ -1,5 +1,11 @@
 # Release notes #
 
+### 2.11.3 (2020-02-19) ###
+
+* DRM: Fix issue switching from protected content that uses a 16-byte
+  initialization vector to one that uses an 8-byte initialization vector
+  ([#6982](https://github.com/google/ExoPlayer/issues/6982)).
+
 ### 2.11.2 (2020-02-13) ###
 
 * Add Java FLAC extractor

library/core/src/main/java/com/google/android/exoplayer2/decoder/CryptoInfo.java

@@ -25,27 +25,41 @@
 public final class CryptoInfo {
 
   /**
+   * The 16 byte initialization vector. If the initialization vector of the content is shorter than
+   * 16 bytes, 0 byte padding is appended to extend the vector to the required 16 byte length.
+   *
    * @see android.media.MediaCodec.CryptoInfo#iv
    */
   public byte[] iv;
   /**
+   * The 16 byte key id.
+   *
    * @see android.media.MediaCodec.CryptoInfo#key
    */
   public byte[] key;
   /**
+   * The type of encryption that has been applied. Must be one of the {@link C.CryptoMode} values.
+   *
    * @see android.media.MediaCodec.CryptoInfo#mode
    */
-  @C.CryptoMode
-  public int mode;
+  @C.CryptoMode public int mode;
   /**
+   * The number of leading unencrypted bytes in each sub-sample. If null, all bytes are treated as
+   * encrypted and {@link #numBytesOfEncryptedData} must be specified.
+   *
    * @see android.media.MediaCodec.CryptoInfo#numBytesOfClearData
    */
   public int[] numBytesOfClearData;
   /**
+   * The number of trailing encrypted bytes in each sub-sample. If null, all bytes are treated as
+   * clear and {@link #numBytesOfClearData} must be specified.
+   *
    * @see android.media.MediaCodec.CryptoInfo#numBytesOfEncryptedData
    */
   public int[] numBytesOfEncryptedData;
   /**
+   * The number of subSamples that make up the buffer's contents.
+   *
    * @see android.media.MediaCodec.CryptoInfo#numSubSamples
    */
   public int numSubSamples;

library/core/src/main/java/com/google/android/exoplayer2/source/SampleDataQueue.java

@@ -17,6 +17,7 @@
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.decoder.CryptoInfo;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.TrackOutput.CryptoData;
@@ -27,6 +28,7 @@
 import java.io.EOFException;
 import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.util.Arrays;
 
 /** A queue of media sample data. */
 /* package */ class SampleDataQueue {
@@ -228,10 +230,14 @@ private void readEncryptionData(DecoderInputBuffer buffer, SampleExtrasHolder ex
     int ivSize = signalByte & 0x7F;
 
     // Read the initialization vector.
-    if (buffer.cryptoInfo.iv == null) {
-      buffer.cryptoInfo.iv = new byte[16];
+    CryptoInfo cryptoInfo = buffer.cryptoInfo;
+    if (cryptoInfo.iv == null) {
+      cryptoInfo.iv = new byte[16];
+    } else {
+      // Zero out cryptoInfo.iv so that if ivSize < 16, the remaining bytes are correctly set to 0.
+      Arrays.fill(cryptoInfo.iv, (byte) 0);
     }
-    readData(offset, buffer.cryptoInfo.iv, ivSize);
+    readData(offset, cryptoInfo.iv, ivSize);
     offset += ivSize;
 
     // Read the subsample count, if present.
@@ -246,11 +252,11 @@ private void readEncryptionData(DecoderInputBuffer buffer, SampleExtrasHolder ex
     }
 
     // Write the clear and encrypted subsample sizes.
-    int[] clearDataSizes = buffer.cryptoInfo.numBytesOfClearData;
+    @Nullable int[] clearDataSizes = cryptoInfo.numBytesOfClearData;
     if (clearDataSizes == null || clearDataSizes.length < subsampleCount) {
       clearDataSizes = new int[subsampleCount];
     }
-    int[] encryptedDataSizes = buffer.cryptoInfo.numBytesOfEncryptedData;
+    @Nullable int[] encryptedDataSizes = cryptoInfo.numBytesOfEncryptedData;
     if (encryptedDataSizes == null || encryptedDataSizes.length < subsampleCount) {
       encryptedDataSizes = new int[subsampleCount];
     }
@@ -271,12 +277,12 @@ private void readEncryptionData(DecoderInputBuffer buffer, SampleExtrasHolder ex
 
     // Populate the cryptoInfo.
     CryptoData cryptoData = extrasHolder.cryptoData;
-    buffer.cryptoInfo.set(
+    cryptoInfo.set(
         subsampleCount,
         clearDataSizes,
         encryptedDataSizes,
         cryptoData.encryptionKey,
-        buffer.cryptoInfo.iv,
+        cryptoInfo.iv,
         cryptoData.cryptoMode,
         cryptoData.encryptedBlocks,
         cryptoData.clearBlocks);

library/core/src/test/java/com/google/android/exoplayer2/source/SampleQueueTest.java

@@ -15,13 +15,15 @@
  */
 package com.google.android.exoplayer2.source;
 
+import static com.google.android.exoplayer2.C.BUFFER_FLAG_ENCRYPTED;
 import static com.google.android.exoplayer2.C.BUFFER_FLAG_KEY_FRAME;
 import static com.google.android.exoplayer2.C.RESULT_BUFFER_READ;
 import static com.google.android.exoplayer2.C.RESULT_FORMAT_READ;
 import static com.google.android.exoplayer2.C.RESULT_NOTHING_READ;
 import static com.google.common.truth.Truth.assertThat;
 import static java.lang.Long.MIN_VALUE;
 import static java.util.Arrays.copyOfRange;
+import static org.junit.Assert.assertArrayEquals;
 import static org.mockito.Mockito.when;
 
 import androidx.annotation.Nullable;
@@ -114,17 +116,13 @@ public final class SampleQueueTest {
         C.BUFFER_FLAG_KEY_FRAME, C.BUFFER_FLAG_ENCRYPTED, 0, C.BUFFER_FLAG_ENCRYPTED,
       };
   private static final long[] ENCRYPTED_SAMPLE_TIMESTAMPS = new long[] {0, 1000, 2000, 3000};
-  private static final Format[] ENCRYPTED_SAMPLES_FORMATS =
+  private static final Format[] ENCRYPTED_SAMPLE_FORMATS =
       new Format[] {FORMAT_ENCRYPTED, FORMAT_ENCRYPTED, FORMAT_1, FORMAT_ENCRYPTED};
   /** Encrypted samples require the encryption preamble. */
-  private static final int[] ENCRYPTED_SAMPLES_SIZES = new int[] {1, 3, 1, 3};
+  private static final int[] ENCRYPTED_SAMPLE_SIZES = new int[] {1, 3, 1, 3};
 
-  private static final int[] ENCRYPTED_SAMPLES_OFFSETS = new int[] {7, 4, 3, 0};
-  private static final byte[] ENCRYPTED_SAMPLES_DATA = new byte[8];
-
-  static {
-    Arrays.fill(ENCRYPTED_SAMPLES_DATA, (byte) 1);
-  }
+  private static final int[] ENCRYPTED_SAMPLE_OFFSETS = new int[] {7, 4, 3, 0};
+  private static final byte[] ENCRYPTED_SAMPLE_DATA = new byte[] {1, 1, 1, 1, 1, 1, 1, 1};
 
   private static final TrackOutput.CryptoData DUMMY_CRYPTO_DATA =
       new TrackOutput.CryptoData(C.CRYPTO_MODE_AES_CTR, new byte[16], 0, 0);
@@ -461,6 +459,60 @@ public void testAllowPlaceholderSessionPopulatesDrmSession() {
             /* decodeOnlyUntilUs= */ 0);
     assertThat(result).isEqualTo(RESULT_FORMAT_READ);
     assertThat(formatHolder.drmSession).isSameInstanceAs(mockDrmSession);
+    assertReadEncryptedSample(/* sampleIndex= */ 3);
+  }
+
+  @Test
+  @SuppressWarnings("unchecked")
+  public void testTrailingCryptoInfoInitializationVectorBytesZeroed() {
+    when(mockDrmSession.getState()).thenReturn(DrmSession.STATE_OPENED_WITH_KEYS);
+    DrmSession<ExoMediaCrypto> mockPlaceholderDrmSession =
+        (DrmSession<ExoMediaCrypto>) Mockito.mock(DrmSession.class);
+    when(mockPlaceholderDrmSession.getState()).thenReturn(DrmSession.STATE_OPENED_WITH_KEYS);
+    when(mockDrmSessionManager.acquirePlaceholderSession(
+            ArgumentMatchers.any(), ArgumentMatchers.anyInt()))
+        .thenReturn(mockPlaceholderDrmSession);
+
+    writeFormat(ENCRYPTED_SAMPLE_FORMATS[0]);
+    byte[] sampleData = new byte[] {0, 1, 2};
+    byte[] initializationVector = new byte[] {7, 6, 5, 4, 3, 2, 1, 0};
+    byte[] encryptedSampleData =
+        TestUtil.joinByteArrays(
+            new byte[] {
+              0x08, // subsampleEncryption = false (1 bit), ivSize = 8 (7 bits).
+            },
+            initializationVector,
+            sampleData);
+    writeSample(
+        encryptedSampleData, /* timestampUs= */ 0, BUFFER_FLAG_KEY_FRAME | BUFFER_FLAG_ENCRYPTED);
+
+    int result =
+        sampleQueue.read(
+            formatHolder,
+            inputBuffer,
+            /* formatRequired= */ false,
+            /* loadingFinished= */ false,
+            /* decodeOnlyUntilUs= */ 0);
+    assertThat(result).isEqualTo(RESULT_FORMAT_READ);
+
+    // Fill cryptoInfo.iv with non-zero data. When the 8 byte initialization vector is written into
+    // it, we expect the trailing 8 bytes to be zeroed.
+    inputBuffer.cryptoInfo.iv = new byte[16];
+    Arrays.fill(inputBuffer.cryptoInfo.iv, (byte) 1);
+
+    result =
+        sampleQueue.read(
+            formatHolder,
+            inputBuffer,
+            /* formatRequired= */ false,
+            /* loadingFinished= */ false,
+            /* decodeOnlyUntilUs= */ 0);
+    assertThat(result).isEqualTo(RESULT_BUFFER_READ);
+
+    // Assert cryptoInfo.iv contains the 8-byte initialization vector and that the trailing 8 bytes
+    // have been zeroed.
+    byte[] expectedInitializationVector = Arrays.copyOf(initializationVector, 16);
+    assertArrayEquals(expectedInitializationVector, inputBuffer.cryptoInfo.iv);
   }
 
   @Test
@@ -995,11 +1047,11 @@ private void writeTestData() {
 
   private void writeTestDataWithEncryptedSections() {
     writeTestData(
-        ENCRYPTED_SAMPLES_DATA,
-        ENCRYPTED_SAMPLES_SIZES,
-        ENCRYPTED_SAMPLES_OFFSETS,
+        ENCRYPTED_SAMPLE_DATA,
+        ENCRYPTED_SAMPLE_SIZES,
+        ENCRYPTED_SAMPLE_OFFSETS,
         ENCRYPTED_SAMPLE_TIMESTAMPS,
-        ENCRYPTED_SAMPLES_FORMATS,
+        ENCRYPTED_SAMPLE_FORMATS,
         ENCRYPTED_SAMPLES_FLAGS);
   }
 
@@ -1033,7 +1085,12 @@ private void writeFormat(Format format) {
   /** Writes a single sample to {@code sampleQueue}. */
   private void writeSample(byte[] data, long timestampUs, int sampleFlags) {
     sampleQueue.sampleData(new ParsableByteArray(data), data.length);
-    sampleQueue.sampleMetadata(timestampUs, sampleFlags, data.length, 0, null);
+    sampleQueue.sampleMetadata(
+        timestampUs,
+        sampleFlags,
+        data.length,
+        /* offset= */ 0,
+        (sampleFlags & C.BUFFER_FLAG_ENCRYPTED) != 0 ? DUMMY_CRYPTO_DATA : null);
   }
 
   /**
@@ -1206,7 +1263,7 @@ private void assertReadFormat(boolean formatRequired, Format format) {
   }
 
   private void assertReadEncryptedSample(int sampleIndex) {
-    byte[] sampleData = new byte[ENCRYPTED_SAMPLES_SIZES[sampleIndex]];
+    byte[] sampleData = new byte[ENCRYPTED_SAMPLE_SIZES[sampleIndex]];
     Arrays.fill(sampleData, (byte) 1);
     boolean isKeyFrame = (ENCRYPTED_SAMPLES_FLAGS[sampleIndex] & C.BUFFER_FLAG_KEY_FRAME) != 0;
     boolean isEncrypted = (ENCRYPTED_SAMPLES_FLAGS[sampleIndex] & C.BUFFER_FLAG_ENCRYPTED) != 0;
@@ -1216,7 +1273,7 @@ private void assertReadEncryptedSample(int sampleIndex) {
         isEncrypted,
         sampleData,
         /* offset= */ 0,
-        ENCRYPTED_SAMPLES_SIZES[sampleIndex] - (isEncrypted ? 2 : 0));
+        ENCRYPTED_SAMPLE_SIZES[sampleIndex] - (isEncrypted ? 2 : 0));
   }
 
   /**