Line data    Source code

       1             : /*
       2             :  * Licensed to the Apache Software Foundation (ASF) under one
       3             :  * or more contributor license agreements. See the NOTICE file
       4             :  * distributed with this work for additional information
       5             :  * regarding copyright ownership. The ASF licenses this file
       6             :  * to you under the Apache License, Version 2.0 (the
       7             :  * "License"); you may not use this file except in compliance
       8             :  * with the License. You may obtain a copy of the License at
       9             :  *
      10             :  * http://www.apache.org/licenses/LICENSE-2.0
      11             :  *
      12             :  * Unless required by applicable law or agreed to in writing,
      13             :  * software distributed under the License is distributed on an
      14             :  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
      15             :  * KIND, either express or implied. See the License for the
      16             :  * specific language governing permissions and limitations
      17             :  * under the License.
      18             :  */
      19             : 
      20             : /**
      21             :  * This file is based on sshd-contrib Apache SSHD Mina project. Original commit:
      22             :  * https://github.com/apache/mina-sshd/commit/11b33dee37b5b9c71a40a8a98a42007e3687131e
      23             :  */
      24             : package com.google.gerrit.sshd;
      25             : 
      26             : import com.google.common.flogger.FluentLogger;
      27             : import java.io.IOException;
      28             : import org.apache.sshd.common.AttributeRepository.AttributeKey;
      29             : import org.apache.sshd.common.SshConstants;
      30             : import org.apache.sshd.common.channel.Channel;
      31             : import org.apache.sshd.common.channel.ChannelListener;
      32             : import org.apache.sshd.common.channel.exception.SshChannelNotFoundException;
      33             : import org.apache.sshd.common.session.ConnectionService;
      34             : import org.apache.sshd.common.session.Session;
      35             : import org.apache.sshd.common.session.helpers.DefaultUnknownChannelReferenceHandler;
      36             : import org.apache.sshd.common.util.buffer.Buffer;
      37             : 
      38             : /**
      39             :  * Makes sure that the referenced "unknown" channel identifier is one that was assigned in
      40             :  * the past. <B>Note:</B> it relies on the fact that the default {@code ConnectionService}
      41             :  * implementation assigns channels identifiers in ascending order.
      42             :  *
      43             :  * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
      44             :  */
      45             : public class ChannelIdTrackingUnknownChannelReferenceHandler
      46             :     extends DefaultUnknownChannelReferenceHandler implements ChannelListener {
      47          17 :   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
      48          17 :   public static final AttributeKey<Long> LAST_CHANNEL_ID_KEY = new AttributeKey<>();
      49             : 
      50          17 :   public static final ChannelIdTrackingUnknownChannelReferenceHandler TRACKER =
      51             :       new ChannelIdTrackingUnknownChannelReferenceHandler();
      52             : 
      53             :   public ChannelIdTrackingUnknownChannelReferenceHandler() {
      54          17 :     super();
      55          17 :   }
      56             : 
      57             :   @Override
      58             :   public void channelInitialized(Channel channel) {
      59           0 :     long channelId = channel.getChannelId();
      60           0 :     Session session = channel.getSession();
      61           0 :     Long lastTracked = session.setAttribute(LAST_CHANNEL_ID_KEY, channelId);
      62           0 :     logger.atFine().log(
      63             :         "channelInitialized(%s) updated last tracked channel ID %s => %s",
      64           0 :         channel, lastTracked, channelId);
      65           0 :   }
      66             : 
      67             :   @Override
      68             :   public Channel handleUnknownChannelCommand(
      69             :       ConnectionService service, byte cmd, long channelId, Buffer buffer) throws IOException {
      70           1 :     Session session = service.getSession();
      71           1 :     Long lastTracked = session.getAttribute(LAST_CHANNEL_ID_KEY);
      72           1 :     if ((lastTracked != null) && (channelId <= lastTracked.intValue())) {
      73             :       // Use TRACE level in order to avoid messages flooding
      74           0 :       logger.atFinest().log(
      75             :           "handleUnknownChannelCommand(%s) apply default handling for %s on channel=%s (lastTracked=%s)",
      76           0 :           session, SshConstants.getCommandMessageName(cmd), channelId, lastTracked);
      77           0 :       return super.handleUnknownChannelCommand(service, cmd, channelId, buffer);
      78             :     }
      79             : 
      80           1 :     throw new SshChannelNotFoundException(
      81             :         channelId,
      82             :         "Received "
      83           1 :             + SshConstants.getCommandMessageName(cmd)
      84             :             + " on unassigned channel "
      85             :             + channelId
      86             :             + " (last assigned="
      87             :             + lastTracked
      88             :             + ")");
      89             :   }
      90             : }