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/*
* 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('_', '/');
}
}
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