Add gzip support to WebServerDispatcher

Add a test to DataSourceContractTest that asserts the gzip flag is
either ignored or handled correctly.

Add a test resource to DefaultHttpDataSourceContracTest that enables
gzip compression on the 'server' and checks it's handled correctly by
the client.

PiperOrigin-RevId: 352574359

library/common/build.gradle

@@ -36,6 +36,7 @@ dependencies {
     testImplementation 'junit:junit:' + junitVersion
     testImplementation 'com.google.truth:truth:' + truthVersion
     testImplementation 'org.robolectric:robolectric:' + robolectricVersion
+    testImplementation project(modulePrefix + 'testutils')
 }
 
 ext {

library/common/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -91,6 +91,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.zip.DataFormatException;
+import java.util.zip.GZIPOutputStream;
 import java.util.zip.Inflater;
 import org.checkerframework.checker.initialization.qual.UnknownInitialization;
 import org.checkerframework.checker.nullness.compatqual.NullableType;
@@ -2121,6 +2122,17 @@ public static int crc8(byte[] bytes, int start, int end, int initialValue) {
     return initialValue;
   }
 
+  /** Compresses {@code input} using gzip and returns the result in a newly allocated byte array. */
+  public static byte[] gzip(byte[] input) {
+    ByteArrayOutputStream output = new ByteArrayOutputStream();
+    try (GZIPOutputStream os = new GZIPOutputStream(output)) {
+      os.write(input);
+    } catch (IOException e) {
+      throw new AssertionError(e);
+    }
+    return output.toByteArray();
+  }
+
   /**
    * Absolute <i>get</i> method for reading an int value in {@link ByteOrder#BIG_ENDIAN} in a {@link
    * ByteBuffer}. Same as {@link ByteBuffer#getInt(int)} except the buffer's order as returned by

library/common/src/test/java/com/google/android/exoplayer2/util/UtilTest.java

@@ -20,6 +20,7 @@
 import static com.google.android.exoplayer2.util.Util.escapeFileName;
 import static com.google.android.exoplayer2.util.Util.getCodecsOfType;
 import static com.google.android.exoplayer2.util.Util.getStringForTime;
+import static com.google.android.exoplayer2.util.Util.gzip;
 import static com.google.android.exoplayer2.util.Util.minValue;
 import static com.google.android.exoplayer2.util.Util.parseXsDateTime;
 import static com.google.android.exoplayer2.util.Util.parseXsDuration;
@@ -37,6 +38,9 @@
 import android.util.SparseLongArray;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.testutil.TestUtil;
+import com.google.common.io.ByteStreams;
+import java.io.ByteArrayInputStream;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.ArrayList;
@@ -45,6 +49,7 @@
 import java.util.NoSuchElementException;
 import java.util.Random;
 import java.util.zip.Deflater;
+import java.util.zip.GZIPInputStream;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.annotation.Config;
@@ -927,6 +932,17 @@ public void crc8_returnsUpdatedCrc8() {
     assertThat(result).isEqualTo(0x4);
   }
 
+  @Test
+  public void gzip_resultInflatesBackToOriginalValue() throws Exception {
+    byte[] input = TestUtil.buildTestData(20);
+
+    byte[] deflated = gzip(input);
+
+    byte[] inflated =
+        ByteStreams.toByteArray(new GZIPInputStream(new ByteArrayInputStream(deflated)));
+    assertThat(inflated).isEqualTo(input);
+  }
+
   @Test
   public void getBigEndianInt_fromBigEndian() {
     byte[] bytes = {0x1F, 0x2E, 0x3D, 0x4C};

testutils/src/main/java/com/google/android/exoplayer2/testutil/DataSourceContractTest.java

@@ -194,6 +194,43 @@ public void dataSpecWithPositionAndLength_readExpectedRange() throws Exception {
     }
   }
 
+  /**
+   * {@link DataSpec#FLAG_ALLOW_GZIP} should either be ignored by {@link DataSource}
+   * implementations, or correctly handled (i.e. the data is decompressed before being returned from
+   * {@link DataSource#read(byte[], int, int)}).
+   */
+  @Test
+  public void gzipFlagDoesntAffectReturnedData() throws Exception {
+    ImmutableList<TestResource> resources = getTestResources();
+    Assertions.checkArgument(!resources.isEmpty(), "Must provide at least one test resource.");
+
+    for (int i = 0; i < resources.size(); i++) {
+      additionalFailureInfo.setInfo(getFailureLabel(resources, i));
+      TestResource resource = resources.get(i);
+      DataSource dataSource = createDataSource();
+      try {
+        long length =
+            dataSource.open(
+                new DataSpec.Builder()
+                    .setUri(resource.getUri())
+                    .setFlags(DataSpec.FLAG_ALLOW_GZIP)
+                    .build());
+        byte[] data =
+            resource.isEndOfInputExpected()
+                ? Util.readToEnd(dataSource)
+                : Util.readExactly(dataSource, resource.getExpectedBytes().length);
+
+        if (length != C.LENGTH_UNSET) {
+          assertThat(length).isEqualTo(resource.getExpectedBytes().length);
+        }
+        assertThat(data).isEqualTo(resource.getExpectedBytes());
+      } finally {
+        dataSource.close();
+      }
+      additionalFailureInfo.setInfo(null);
+    }
+  }
+
   @Test
   public void resourceNotFound() throws Exception {
     DataSource dataSource = createDataSource();

testutils/src/main/java/com/google/android/exoplayer2/testutil/HttpDataSourceTestEnv.java

@@ -60,6 +60,20 @@ public class HttpDataSourceTestEnv extends ExternalResource {
           .resolvesToUnknownLength(true)
           .build();
 
+  private static final WebServerDispatcher.Resource GZIP_ENABLED =
+      new WebServerDispatcher.Resource.Builder()
+          .setPath("/gzip/enabled")
+          .setData(TestUtil.buildTestData(/* length= */ 20, seed++))
+          .setGzipSupport(WebServerDispatcher.Resource.GZIP_SUPPORT_ENABLED)
+          .build();
+
+  private static final WebServerDispatcher.Resource GZIP_FORCED =
+      new WebServerDispatcher.Resource.Builder()
+          .setPath("/gzip/forced")
+          .setData(TestUtil.buildTestData(/* length= */ 20, seed++))
+          .setGzipSupport(WebServerDispatcher.Resource.GZIP_SUPPORT_FORCED)
+          .build();
+
   private static final WebServerDispatcher.Resource REDIRECTS_TO_RANGE_SUPPORTED =
       RANGE_SUPPORTED.buildUpon().setPath("/redirects/to/range/supported").build();
 
@@ -74,6 +88,8 @@ public ImmutableList<DataSourceContractTest.TestResource> getServedResources() {
         createTestResource("range not supported", RANGE_NOT_SUPPORTED),
         createTestResource(
             "range not supported, length unknown", RANGE_NOT_SUPPORTED_LENGTH_UNKNOWN),
+        createTestResource("gzip enabled", GZIP_ENABLED),
+        createTestResource("gzip forced", GZIP_FORCED),
         createTestResource(
             "302 redirect", REDIRECTS_TO_RANGE_SUPPORTED, /* server= */ redirectionServer));
   }
@@ -91,7 +107,9 @@ protected void before() throws Throwable {
                 RANGE_SUPPORTED,
                 RANGE_SUPPORTED_LENGTH_UNKNOWN,
                 RANGE_NOT_SUPPORTED,
-                RANGE_NOT_SUPPORTED_LENGTH_UNKNOWN)));
+                RANGE_NOT_SUPPORTED_LENGTH_UNKNOWN,
+                GZIP_ENABLED,
+                GZIP_FORCED)));
 
     redirectionServer.start();
     redirectionServer.setDispatcher(