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.authenticator;
  
  import org.apache.kafka.common.config.SaslConfigs;
  import org.apache.kafka.common.security.auth.AuthenticateCallbackHandler;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.List;
  import java.util.Map;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.auth.login.AppConfigurationEntry;
  import javax.security.sasl.AuthorizeCallback;
  import javax.security.sasl.RealmCallback;
  
  /**
   * Default callback handler for Sasl servers. The callbacks required for all the SASL
   * mechanisms enabled in the server should be supported by this callback handler. See
   * <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/security/sasl/sasl-refguide.html">Java SASL API</a>
   * for the list of SASL callback handlers required for each SASL mechanism.
   */
  public class SaslServerCallbackHandler implements AuthenticateCallbackHandler {
      private static final Logger LOG = LoggerFactory.getLogger(SaslServerCallbackHandler.class);
  
      private String mechanism;
  
      @Override
      public void configure(Map<String, ?> configs, String mechanism, List<AppConfigurationEntry> jaasConfigEntries) {
          this.mechanism = mechanism;
      }
  
      @Override
      public void handle(Callback[] callbacks) throws UnsupportedCallbackException {
          for (Callback callback : callbacks) {
              if (callback instanceof RealmCallback)
                  handleRealmCallback((RealmCallback) callback);
              else if (callback instanceof AuthorizeCallback && mechanism.equals(SaslConfigs.GSSAPI_MECHANISM))
                  handleAuthorizeCallback((AuthorizeCallback) callback);
              else
                  throw new UnsupportedCallbackException(callback);
          }
      }
  
      private void handleRealmCallback(RealmCallback rc) {
          LOG.trace("Client supplied realm: {} ", rc.getDefaultText());
          rc.setText(rc.getDefaultText());
      }
  
      private void handleAuthorizeCallback(AuthorizeCallback ac) {
          String authenticationID = ac.getAuthenticationID();
          String authorizationID = ac.getAuthorizationID();
          LOG.info("Successfully authenticated client: authenticationID={}; authorizationID={}.",
                  authenticationID, authorizationID);
          ac.setAuthorized(true);
          ac.setAuthorizedID(authenticationID);
      }
  
      @Override
      public void close() {
      }
  }
  