content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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.apache.kafka.common.security.oauthbearer;
  
  import org.apache.kafka.common.security.oauthbearer.internals.secured.ClientCredentialsRequestFormatter;
  import org.apache.kafka.common.security.oauthbearer.internals.secured.ConfigurationUtils;
  import org.apache.kafka.common.utils.Utils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.net.URL;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  
  import javax.security.auth.login.AppConfigurationEntry;
  
  import static org.apache.kafka.common.config.SaslConfigs.SASL_OAUTHBEARER_TOKEN_ENDPOINT_URL;
  
  /**
   * {@code DefaultJwtRetriever} instantiates and delegates {@link JwtRetriever} API calls to an embedded implementation
   * based on configuration:
   *
   * <ul>
   *     <li>
   *         If the value of <code>sasl.oauthbearer.token.endpoint.url</code> is set to a value that starts with the
   *         <code>file</code> protocol (e.g. <code>file:/tmp/path/to/a/static-jwt.json</code>), an instance of
   *         {@link FileJwtRetriever} will be used as the underlying {@link JwtRetriever}. Otherwise, the URL is
   *         assumed to be an HTTP/HTTPS-based URL, and an instance of {@link ClientCredentialsRequestFormatter} will
   *         be created and used.
   *     </li>
   * </ul>
   *
   * The configuration required by the individual {@code JwtRetriever} classes will likely differ. Please refer to the
   * official Apache Kafka documentation for more information on these, and related configuration.
   */
  public class DefaultJwtRetriever implements JwtRetriever {
  
      private static final Logger LOG = LoggerFactory.getLogger(DefaultJwtRetriever.class);
  
      private JwtRetriever delegate;
  
      @Override
      public void configure(Map<String, ?> configs, String saslMechanism, List<AppConfigurationEntry> jaasConfigEntries) {
          ConfigurationUtils cu = new ConfigurationUtils(configs, saslMechanism);
          URL tokenEndpointUrl = cu.validateUrl(SASL_OAUTHBEARER_TOKEN_ENDPOINT_URL);
  
          if (tokenEndpointUrl.getProtocol().toLowerCase(Locale.ROOT).equals("file"))
              delegate = new FileJwtRetriever();
          else
              delegate = new ClientCredentialsJwtRetriever();
  
          LOG.debug("Created instance of {} as delegate", delegate.getClass().getName());
          delegate.configure(configs, saslMechanism, jaasConfigEntries);
      }
  
      @Override
      public String retrieve() throws JwtRetrieverException {
          if (delegate == null)
              throw new IllegalStateException("JWT retriever delegate is null; please call configure() first");
  
          return delegate.retrieve();
      }
  
      @Override
      public void close() throws IOException {
          Utils.closeQuietly(delegate, "JWT retriever delegate");
      }
  
      JwtRetriever delegate() {
          return delegate;
      }
  }
  