001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.protocol.datatransfer;
019
020import java.net.InetAddress;
021
022import org.apache.hadoop.conf.Configurable;
023import org.apache.hadoop.conf.Configuration;
024import org.apache.hadoop.hdfs.DFSConfigKeys;
025import org.apache.hadoop.util.ReflectionUtils;
026
027/**
028 * Class used to indicate whether a channel is trusted or not.
029 * The default implementation is to return false indicating that
030 * the channel is not trusted.
031 * This class can be overridden to provide custom logic to determine
032 * whether a channel is trusted or not. 
033 * The custom class can be specified via configuration.
034 *
035 */
036public class TrustedChannelResolver implements Configurable {
037  Configuration conf;
038
039  /**
040   * Returns an instance of TrustedChannelResolver.
041   * Looks up the configuration to see if there is custom class specified.
042   * @param conf
043   * @return TrustedChannelResolver
044   */
045  public static TrustedChannelResolver getInstance(Configuration conf) {
046    Class<? extends TrustedChannelResolver> clazz =
047      conf.getClass(
048          DFSConfigKeys.DFS_TRUSTEDCHANNEL_RESOLVER_CLASS,
049          TrustedChannelResolver.class, TrustedChannelResolver.class);
050    return ReflectionUtils.newInstance(clazz, conf);
051  }
052
053  @Override
054  public void setConf(Configuration conf) {
055    this.conf = conf;
056  }
057
058  @Override
059  public Configuration getConf() {
060    return conf;
061  }
062
063  /**
064   * Return boolean value indicating whether a channel is trusted or not
065   * from a client's perspective.
066   * @return true if the channel is trusted and false otherwise.
067   */
068  public boolean isTrusted() {
069    return false;
070  }
071
072
073  /**
074   * Identify boolean value indicating whether a channel is trusted or not.
075   * @param peerAddress address of the peer
076   * @return true if the channel is trusted and false otherwise.
077   */
078  public boolean isTrusted(InetAddress peerAddress) {
079    return false;
080  }
081}