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.network;
  
  import org.apache.kafka.common.KafkaException;
  import org.apache.kafka.common.memory.MemoryPool;
  import org.apache.kafka.common.security.auth.KafkaPrincipal;
  import org.apache.kafka.common.security.auth.KafkaPrincipalBuilder;
  import org.apache.kafka.common.security.auth.KafkaPrincipalSerde;
  import org.apache.kafka.common.security.auth.PlaintextAuthenticationContext;
  import org.apache.kafka.common.utils.Utils;
  
  import java.io.Closeable;
  import java.net.InetAddress;
  import java.nio.channels.SelectionKey;
  import java.util.Map;
  import java.util.Optional;
  import java.util.function.Supplier;
  
  public class PlaintextChannelBuilder implements ChannelBuilder {
      private final ListenerName listenerName;
      private Map<String, ?> configs;
  
      /**
       * Constructs a plaintext channel builder. ListenerName is non-null whenever
       * it's instantiated in the broker and null otherwise.
       */
      public PlaintextChannelBuilder(ListenerName listenerName) {
          this.listenerName = listenerName;
      }
  
      public void configure(Map<String, ?> configs) throws KafkaException {
          this.configs = configs;
      }
  
      @Override
      public KafkaChannel buildChannel(String id, SelectionKey key, int maxReceiveSize,
                                       MemoryPool memoryPool, ChannelMetadataRegistry metadataRegistry) throws KafkaException {
          PlaintextTransportLayer transportLayer = null;
          try {
              transportLayer = buildTransportLayer(key);
              final PlaintextTransportLayer finalTransportLayer = transportLayer;
              Supplier<Authenticator> authenticatorCreator = () -> new PlaintextAuthenticator(configs, finalTransportLayer, listenerName);
              return buildChannel(id, transportLayer, authenticatorCreator, maxReceiveSize,
                      memoryPool != null ? memoryPool : MemoryPool.NONE, metadataRegistry);
          } catch (Exception e) {
              // Ideally these resources are closed by the KafkaChannel but this builder should close the resources instead
              // if an error occurs due to which KafkaChannel is not created.
              Utils.closeQuietly(transportLayer, "transport layer for channel Id: " + id);
              throw new KafkaException(e);
          }
      }
  
      // visible for testing
      KafkaChannel buildChannel(String id, TransportLayer transportLayer, Supplier<Authenticator> authenticatorCreator,
                                int maxReceiveSize, MemoryPool memoryPool, ChannelMetadataRegistry metadataRegistry) {
          return new KafkaChannel(id, transportLayer, authenticatorCreator, maxReceiveSize, memoryPool, metadataRegistry);
      }
  
      protected PlaintextTransportLayer buildTransportLayer(SelectionKey key) {
          return new PlaintextTransportLayer(key);
      }
  
      @Override
      public void close() {}
  
      private static class PlaintextAuthenticator implements Authenticator {
          private final PlaintextTransportLayer transportLayer;
          private final KafkaPrincipalBuilder principalBuilder;
          private final ListenerName listenerName;
  
          private PlaintextAuthenticator(Map<String, ?> configs, PlaintextTransportLayer transportLayer, ListenerName listenerName) {
              this.transportLayer = transportLayer;
              this.principalBuilder = ChannelBuilders.createPrincipalBuilder(configs, null, null);
              this.listenerName = listenerName;
          }
  
          @Override
          public void authenticate() {}
  
          @Override
          public KafkaPrincipal principal() {
              InetAddress clientAddress = transportLayer.socketChannel().socket().getInetAddress();
              // listenerName should only be null in Client mode where principal() should not be called
              if (listenerName == null)
                  throw new IllegalStateException("Unexpected call to principal() when listenerName is null");
              return principalBuilder.build(new PlaintextAuthenticationContext(clientAddress, listenerName.value()));
          }
  
          @Override
          public Optional<KafkaPrincipalSerde> principalSerde() {
              return principalBuilder instanceof KafkaPrincipalSerde ? Optional.of((KafkaPrincipalSerde) principalBuilder) : Optional.empty();
          }
  
          @Override
          public boolean complete() {
              return true;
          }
  
          @Override
          public void close() {
              if (principalBuilder instanceof Closeable)
                  Utils.closeQuietly((Closeable) principalBuilder, "principal builder");
          }
      }
  
  }
  