1 files changed, 208 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mp4/PsshAtomUtil.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mp4/PsshAtomUtil.java
new file mode 100644
index 0000000000..ddb13aeb9c
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mp4/PsshAtomUtil.java
@@ -0,0 +1,208 @@
+/*
+ * Copyright (C) 2016 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.mp4;
+
+import androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Log;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import java.nio.ByteBuffer;
+import java.util.UUID;
+
+/**
+ * Utility methods for handling PSSH atoms.
+ */
+public final class PsshAtomUtil {
+
+  private static final String TAG = "PsshAtomUtil";
+
+  private PsshAtomUtil() {}
+
+  /**
+   * Builds a version 0 PSSH atom for a given system id, containing the given data.
+   *
+   * @param systemId The system id of the scheme.
+   * @param data The scheme specific data.
+   * @return The PSSH atom.
+   */
+  public static byte[] buildPsshAtom(UUID systemId, @Nullable byte[] data) {
+    return buildPsshAtom(systemId, null, data);
+  }
+
+  /**
+   * Builds a PSSH atom for the given system id, containing the given key ids and data.
+   *
+   * @param systemId The system id of the scheme.
+   * @param keyIds The key ids for a version 1 PSSH atom, or null for a version 0 PSSH atom.
+   * @param data The scheme specific data.
+   * @return The PSSH atom.
+   */
+  // dereference of possibly-null reference keyId
+  @SuppressWarnings({"ParameterNotNullable", "nullness:dereference.of.nullable"})
+  public static byte[] buildPsshAtom(
+      UUID systemId, @Nullable UUID[] keyIds, @Nullable byte[] data) {
+    int dataLength = data != null ? data.length : 0;
+    int psshBoxLength = Atom.FULL_HEADER_SIZE + 16 /* SystemId */ + 4 /* DataSize */ + dataLength;
+    if (keyIds != null) {
+      psshBoxLength += 4 /* KID_count */ + (keyIds.length * 16) /* KIDs */;
+    }
+    ByteBuffer psshBox = ByteBuffer.allocate(psshBoxLength);
+    psshBox.putInt(psshBoxLength);
+    psshBox.putInt(Atom.TYPE_pssh);
+    psshBox.putInt(keyIds != null ? 0x01000000 : 0 /* version=(buildV1Atom ? 1 : 0), flags=0 */);
+    psshBox.putLong(systemId.getMostSignificantBits());
+    psshBox.putLong(systemId.getLeastSignificantBits());
+    if (keyIds != null) {
+      psshBox.putInt(keyIds.length);
+      for (UUID keyId : keyIds) {
+        psshBox.putLong(keyId.getMostSignificantBits());
+        psshBox.putLong(keyId.getLeastSignificantBits());
+      }
+    }
+    if (data != null && data.length != 0) {
+      psshBox.putInt(data.length);
+      psshBox.put(data);
+    } // Else the last 4 bytes are a 0 DataSize.
+    return psshBox.array();
+  }
+
+  /**
+   * Returns whether the data is a valid PSSH atom.
+   *
+   * @param data The data to parse.
+   * @return Whether the data is a valid PSSH atom.
+   */
+  public static boolean isPsshAtom(byte[] data) {
+    return parsePsshAtom(data) != null;
+  }
+
+  /**
+   * Parses the UUID from a PSSH atom. Version 0 and 1 PSSH atoms are supported.
+   *
+   * <p>The UUID is only parsed if the data is a valid PSSH atom.
+   *
+   * @param atom The atom to parse.
+   * @return The parsed UUID. Null if the input is not a valid PSSH atom, or if the PSSH atom has an
+   *     unsupported version.
+   */
+  public static @Nullable UUID parseUuid(byte[] atom) {
+    PsshAtom parsedAtom = parsePsshAtom(atom);
+    if (parsedAtom == null) {
+      return null;
+    }
+    return parsedAtom.uuid;
+  }
+
+  /**
+   * Parses the version from a PSSH atom. Version 0 and 1 PSSH atoms are supported.
+   * <p>
+   * The version is only parsed if the data is a valid PSSH atom.
+   *
+   * @param atom The atom to parse.
+   * @return The parsed version. -1 if the input is not a valid PSSH atom, or if the PSSH atom has
+   *     an unsupported version.
+   */
+  public static int parseVersion(byte[] atom) {
+    PsshAtom parsedAtom = parsePsshAtom(atom);
+    if (parsedAtom == null) {
+      return -1;
+    }
+    return parsedAtom.version;
+  }
+
+  /**
+   * Parses the scheme specific data from a PSSH atom. Version 0 and 1 PSSH atoms are supported.
+   *
+   * <p>The scheme specific data is only parsed if the data is a valid PSSH atom matching the given
+   * UUID, or if the data is a valid PSSH atom of any type in the case that the passed UUID is null.
+   *
+   * @param atom The atom to parse.
+   * @param uuid The required UUID of the PSSH atom, or null to accept any UUID.
+   * @return The parsed scheme specific data. Null if the input is not a valid PSSH atom, or if the
+   *     PSSH atom has an unsupported version, or if the PSSH atom does not match the passed UUID.
+   */
+  public static @Nullable byte[] parseSchemeSpecificData(byte[] atom, UUID uuid) {
+    PsshAtom parsedAtom = parsePsshAtom(atom);
+    if (parsedAtom == null) {
+      return null;
+    }
+    if (uuid != null && !uuid.equals(parsedAtom.uuid)) {
+      Log.w(TAG, "UUID mismatch. Expected: " + uuid + ", got: " + parsedAtom.uuid + ".");
+      return null;
+    }
+    return parsedAtom.schemeData;
+  }
+
+  /**
+   * Parses a PSSH atom. Version 0 and 1 PSSH atoms are supported.
+   *
+   * @param atom The atom to parse.
+   * @return The parsed PSSH atom. Null if the input is not a valid PSSH atom, or if the PSSH atom
+   *     has an unsupported version.
+   */
+  // TODO: Support parsing of the key ids for version 1 PSSH atoms.
+  private static @Nullable PsshAtom parsePsshAtom(byte[] atom) {
+    ParsableByteArray atomData = new ParsableByteArray(atom);
+    if (atomData.limit() < Atom.FULL_HEADER_SIZE + 16 /* UUID */ + 4 /* DataSize */) {
+      // Data too short.
+      return null;
+    }
+    atomData.setPosition(0);
+    int atomSize = atomData.readInt();
+    if (atomSize != atomData.bytesLeft() + 4) {
+      // Not an atom, or incorrect atom size.
+      return null;
+    }
+    int atomType = atomData.readInt();
+    if (atomType != Atom.TYPE_pssh) {
+      // Not an atom, or incorrect atom type.
+      return null;
+    }
+    int atomVersion = Atom.parseFullAtomVersion(atomData.readInt());
+    if (atomVersion > 1) {
+      Log.w(TAG, "Unsupported pssh version: " + atomVersion);
+      return null;
+    }
+    UUID uuid = new UUID(atomData.readLong(), atomData.readLong());
+    if (atomVersion == 1) {
+      int keyIdCount = atomData.readUnsignedIntToInt();
+      atomData.skipBytes(16 * keyIdCount);
+    }
+    int dataSize = atomData.readUnsignedIntToInt();
+    if (dataSize != atomData.bytesLeft()) {
+      // Incorrect dataSize.
+      return null;
+    }
+    byte[] data = new byte[dataSize];
+    atomData.readBytes(data, 0, dataSize);
+    return new PsshAtom(uuid, atomVersion, data);
+  }
+
+  // TODO: Consider exposing this and making parsePsshAtom public.
+  private static class PsshAtom {
+
+    private final UUID uuid;
+    private final int version;
+    private final byte[] schemeData;
+
+    public PsshAtom(UUID uuid, int version, byte[] schemeData) {
+      this.uuid = uuid;
+      this.version = version;
+      this.schemeData = schemeData;
+    }
+
+  }
+
+}