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.celeborn.common.network.sasl.anonymous;
  
  import static org.apache.celeborn.common.network.sasl.SaslUtils.*;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Map;
  
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.sasl.SaslClient;
  import javax.security.sasl.SaslClientFactory;
  import javax.security.sasl.SaslException;
  
  import com.google.common.base.Preconditions;
  
  /**
   * This implements the {@code SaslClientFactory} for the ANONYMOUS SASL mechanism. It allows the
   * creation of SASL clients that can perform ANONYMOUS authentication with a remote server.
   */
  public class AnonymousSaslClientFactory implements SaslClientFactory {
  
    /**
     * Creates a SASL client for the ANONYMOUS mechanism.
     *
     * @param mechanisms The list of SASL mechanisms.
     * @param authorizationId The authorization ID, typically null for ANONYMOUS.
     * @param protocol The name of the protocol being used.
     * @param serverName The name of the server.
     * @param props A map of properties to configure the SASL client.
     * @param cbh A callback handler for handling challenges.
     * @return A {@code CelebornAnonymousSaslClient} instance if ANONYMOUS is requested, or null
     *     otherwise.
     * @throws SaslException
     */
    @Override
    public SaslClient createSaslClient(
        String[] mechanisms,
        String authorizationId,
        String protocol,
        String serverName,
        Map<String, ?> props,
        CallbackHandler cbh)
        throws SaslException {
      Preconditions.checkNotNull(mechanisms);
      for (String mech : mechanisms) {
        if (mech.equals(ANONYMOUS)) {
          return new CelebornAnonymousSaslClient();
        }
      }
      return null;
    }
  
    @Override
    public String[] getMechanismNames(Map<String, ?> props) {
      return new String[] {ANONYMOUS};
    }
  
    static class CelebornAnonymousSaslClient implements SaslClient {
  
      private boolean isCompleted = false;
  
      @Override
      public String getMechanismName() {
        return ANONYMOUS;
      }
  
      @Override
      public boolean hasInitialResponse() {
        return false;
      }
  
      @Override
      public byte[] evaluateChallenge(byte[] challenge) throws SaslException {
        if (isCompleted) {
          throw new IllegalStateException("Authentication has already completed.");
        }
        isCompleted = true;
        return ANONYMOUS.getBytes(StandardCharsets.UTF_8);
      }
  
      @Override
      public boolean isComplete() {
        return isCompleted;
      }
  
      @Override
      public byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException {
        throw new IllegalStateException("ANONYMOUS mechanism does not support wrap/unwrap");
      }
  
      @Override
      public byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException {
        throw new IllegalStateException("ANONYMOUS mechanism does not support wrap/unwrap");
      }
  
      @Override
      public Object getNegotiatedProperty(String propName) {
        return null;
      }
  
      @Override
      public void dispose() throws SaslException {
        // No resources to cleanup for ANONYMOUS
      }
    }
  }
  