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.security.auth.AuthenticateCallbackHandler;
  import org.apache.kafka.common.security.auth.Login;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.List;
  import java.util.Map;
  
  import javax.security.auth.Subject;
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.PasswordCallback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.auth.login.AppConfigurationEntry;
  import javax.security.auth.login.Configuration;
  import javax.security.auth.login.LoginContext;
  import javax.security.auth.login.LoginException;
  import javax.security.sasl.RealmCallback;
  
  /**
   * Base login class that implements methods common to typical SASL mechanisms.
   */
  public abstract class AbstractLogin implements Login {
      private static final Logger log = LoggerFactory.getLogger(AbstractLogin.class);
  
      private String contextName;
      private Configuration configuration;
      private LoginContext loginContext;
      private AuthenticateCallbackHandler loginCallbackHandler;
  
      @Override
      public void configure(Map<String, ?> configs, String contextName, Configuration configuration,
                            AuthenticateCallbackHandler loginCallbackHandler) {
          this.contextName = contextName;
          this.configuration = configuration;
          this.loginCallbackHandler = loginCallbackHandler;
      }
  
      @Override
      public LoginContext login() throws LoginException {
          loginContext = new LoginContext(contextName, null, loginCallbackHandler, configuration);
          loginContext.login();
          log.info("Successfully logged in.");
          return loginContext;
      }
  
      @Override
      public Subject subject() {
          return loginContext.getSubject();
      }
  
      protected String contextName() {
          return contextName;
      }
  
      protected Configuration configuration() {
          return configuration;
      }
  
      /**
       * Callback handler for creating login context. Login callback handlers
       * should support the callbacks required for the login modules used by
       * the KafkaServer and KafkaClient contexts. Kafka does not support
       * callback handlers which require additional user input.
       *
       */
      public static class DefaultLoginCallbackHandler implements AuthenticateCallbackHandler {
  
          @Override
          public void configure(Map<String, ?> configs, String saslMechanism, List<AppConfigurationEntry> jaasConfigEntries) {
          }
  
          @Override
          public void handle(Callback[] callbacks) throws UnsupportedCallbackException {
              for (Callback callback : callbacks) {
                  if (callback instanceof NameCallback) {
                      NameCallback nc = (NameCallback) callback;
                      nc.setName(nc.getDefaultName());
                  } else if (callback instanceof PasswordCallback) {
                      String errorMessage = "Could not login: the client is being asked for a password, but the Kafka" +
                                   " client code does not currently support obtaining a password from the user.";
                      throw new UnsupportedCallbackException(callback, errorMessage);
                  } else if (callback instanceof RealmCallback) {
                      RealmCallback rc = (RealmCallback) callback;
                      rc.setText(rc.getDefaultText());
                  } else {
                      throw new UnsupportedCallbackException(callback, "Unrecognized SASL Login callback");
                  }
              }
          }
  
          @Override
          public void close() {
          }
      }
  }
  