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/*
* 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.
*/
/**
* This file is based on sshd-contrib Apache SSHD Mina project. Original commit:
* https://github.com/apache/mina-sshd/commit/11b33dee37b5b9c71a40a8a98a42007e3687131e
*/
package com.google.gerrit.sshd;
import com.google.common.flogger.FluentLogger;
import java.io.IOException;
import org.apache.sshd.common.AttributeRepository.AttributeKey;
import org.apache.sshd.common.SshConstants;
import org.apache.sshd.common.channel.Channel;
import org.apache.sshd.common.channel.ChannelListener;
import org.apache.sshd.common.channel.exception.SshChannelNotFoundException;
import org.apache.sshd.common.session.ConnectionService;
import org.apache.sshd.common.session.Session;
import org.apache.sshd.common.session.helpers.DefaultUnknownChannelReferenceHandler;
import org.apache.sshd.common.util.buffer.Buffer;
/**
* Makes sure that the referenced "unknown" channel identifier is one that was assigned in
* the past. <B>Note:</B> it relies on the fact that the default {@code ConnectionService}
* implementation assigns channels identifiers in ascending order.
*
* @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
*/
public class ChannelIdTrackingUnknownChannelReferenceHandler
extends DefaultUnknownChannelReferenceHandler implements ChannelListener {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
public static final AttributeKey<Long> LAST_CHANNEL_ID_KEY = new AttributeKey<>();
public static final ChannelIdTrackingUnknownChannelReferenceHandler TRACKER =
new ChannelIdTrackingUnknownChannelReferenceHandler();
public ChannelIdTrackingUnknownChannelReferenceHandler() {
super();
}
@Override
public void channelInitialized(Channel channel) {
long channelId = channel.getChannelId();
Session session = channel.getSession();
Long lastTracked = session.setAttribute(LAST_CHANNEL_ID_KEY, channelId);
logger.atFine().log(
"channelInitialized(%s) updated last tracked channel ID %s => %s",
channel, lastTracked, channelId);
}
@Override
public Channel handleUnknownChannelCommand(
ConnectionService service, byte cmd, long channelId, Buffer buffer) throws IOException {
Session session = service.getSession();
Long lastTracked = session.getAttribute(LAST_CHANNEL_ID_KEY);
if ((lastTracked != null) && (channelId <= lastTracked.intValue())) {
// Use TRACE level in order to avoid messages flooding
logger.atFinest().log(
"handleUnknownChannelCommand(%s) apply default handling for %s on channel=%s (lastTracked=%s)",
session, SshConstants.getCommandMessageName(cmd), channelId, lastTracked);
return super.handleUnknownChannelCommand(service, cmd, channelId, buffer);
}
throw new SshChannelNotFoundException(
channelId,
"Received "
+ SshConstants.getCommandMessageName(cmd)
+ " on unassigned channel "
+ channelId
+ " (last assigned="
+ lastTracked
+ ")");
}
}