1 files changed, 97 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/drm/ClearKeyUtil.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/drm/ClearKeyUtil.java
new file mode 100644
index 0000000000..770b8511d9
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/drm/ClearKeyUtil.java
@@ -0,0 +1,97 @@
+/*
+ * 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 org.mozilla.thirdparty.com.google.android.exoplayer2.drm;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Log;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+/**
+ * Utility methods for ClearKey.
+ */
+/* package */ final class ClearKeyUtil {
+
+  private static final String TAG = "ClearKeyUtil";
+
+  private ClearKeyUtil() {}
+
+  /**
+   * Adjusts ClearKey request data obtained from the Android ClearKey CDM to be spec compliant.
+   *
+   * @param request The request data.
+   * @return The adjusted request data.
+   */
+  public static byte[] adjustRequestData(byte[] request) {
+    if (Util.SDK_INT >= 27) {
+      return request;
+    }
+    // Prior to O-MR1 the ClearKey CDM encoded the values in the "kids" array using Base64 encoding
+    // rather than Base64Url encoding. See [Internal: b/64388098]. We know the exact request format
+    // from the platform's InitDataParser.cpp. Since there aren't any "+" or "/" symbols elsewhere
+    // in the request, it's safe to fix the encoding by replacement through the whole request.
+    String requestString = Util.fromUtf8Bytes(request);
+    return Util.getUtf8Bytes(base64ToBase64Url(requestString));
+  }
+
+  /**
+   * Adjusts ClearKey response data to be suitable for providing to the Android ClearKey CDM.
+   *
+   * @param response The response data.
+   * @return The adjusted response data.
+   */
+  public static byte[] adjustResponseData(byte[] response) {
+    if (Util.SDK_INT >= 27) {
+      return response;
+    }
+    // Prior to O-MR1 the ClearKey CDM expected Base64 encoding rather than Base64Url encoding for
+    // the "k" and "kid" strings. See [Internal: b/64388098]. We know that the ClearKey CDM only
+    // looks at the k, kid and kty parameters in each key, so can ignore the rest of the response.
+    try {
+      JSONObject responseJson = new JSONObject(Util.fromUtf8Bytes(response));
+      StringBuilder adjustedResponseBuilder = new StringBuilder("{\"keys\":[");
+      JSONArray keysArray = responseJson.getJSONArray("keys");
+      for (int i = 0; i < keysArray.length(); i++) {
+        if (i != 0) {
+          adjustedResponseBuilder.append(",");
+        }
+        JSONObject key = keysArray.getJSONObject(i);
+        adjustedResponseBuilder.append("{\"k\":\"");
+        adjustedResponseBuilder.append(base64UrlToBase64(key.getString("k")));
+        adjustedResponseBuilder.append("\",\"kid\":\"");
+        adjustedResponseBuilder.append(base64UrlToBase64(key.getString("kid")));
+        adjustedResponseBuilder.append("\",\"kty\":\"");
+        adjustedResponseBuilder.append(key.getString("kty"));
+        adjustedResponseBuilder.append("\"}");
+      }
+      adjustedResponseBuilder.append("]}");
+      return Util.getUtf8Bytes(adjustedResponseBuilder.toString());
+    } catch (JSONException e) {
+      Log.e(TAG, "Failed to adjust response data: " + Util.fromUtf8Bytes(response), e);
+      return response;
+    }
+  }
+
+  private static String base64ToBase64Url(String base64) {
+    return base64.replace('+', '-').replace('/', '_');
+  }
+
+  private static String base64UrlToBase64(String base64Url) {
+    return base64Url.replace('-', '+').replace('_', '/');
+  }
+
+}