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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.
 */

package org.apache.commons.vfs2.provider.sftp;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

import org.apache.commons.vfs2.FileSystemOptions;

import com.jcraft.jsch.ChannelExec;
import com.jcraft.jsch.Proxy;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.SocketFactory;

/**
 * Stream based proxy for JSch.
 *
 * 

* Use a command on the proxy that will forward the SSH stream to the target host and port. *

* * @since 2.1 */ public class SftpStreamProxy implements Proxy { /** * Command format using bash built-in TCP stream. */ public static final String BASH_TCP_COMMAND = "/bin/bash -c 'exec 3<>/dev/tcp/%s/%d; cat <&3 & cat >&3; kill $!"; /** * Command format using netcat command. */ public static final String NETCAT_COMMAND = "nc -q 0 %s %d"; private ChannelExec channel; /** * Command pattern to execute on the proxy host. *

* When run, the command output should be forwarded to the target host and port, and its input should be forwarded * from the target host and port. *

* The command will be created for each host/port pair by using {@linkplain String#format(String, Object...)} with * two objects: the target host name ({@linkplain String}) and the target port ({@linkplain Integer}). *

* Here are two examples (that can be easily used by using the static members of this class): *

    *
  • nc -q 0 %s %d to use the netcat command ({@linkplain #NETCAT_COMMAND})
  • *
  • /bin/bash -c 'exec 3<>/dev/tcp/%s/%d; cat <&3 & cat >&3; kill $! will use bash built-in TCP * stream, which can be useful when there is no netcat available. ({@linkplain #BASH_TCP_COMMAND})
  • *
*/ private final String commandFormat; /** * Hostname used to connect to the proxy host. */ private final String proxyHost; /** * The options for connection. */ private final FileSystemOptions proxyOptions; /** * The password to be used for connection. */ private final String proxyPassword; /** * Port used to connect to the proxy host. */ private final int proxyPort; /** * Username used to connect to the proxy host. */ private final String proxyUser; private Session session; /** * Creates a stream proxy. * * @param commandFormat A format string that will be used to create the command to execute on the proxy host using * {@linkplain String#format(String, Object...)}. Two parameters are given to the format command, the * target host name (String) and port (Integer). * @param proxyUser The proxy user * @param proxyPassword The proxy password * @param proxyHost The proxy host * @param proxyPort The port to connect to on the proxy * @param proxyOptions Options used when connecting to the proxy */ public SftpStreamProxy(final String commandFormat, final String proxyUser, final String proxyHost, final int proxyPort, final String proxyPassword, final FileSystemOptions proxyOptions) { this.proxyHost = proxyHost; this.proxyPort = proxyPort; this.proxyUser = proxyUser; this.proxyPassword = proxyPassword; this.commandFormat = commandFormat; this.proxyOptions = proxyOptions; } @Override public void close() { if (channel != null) { channel.disconnect(); } if (session != null) { session.disconnect(); } } @Override public void connect(final SocketFactory socketFactory, final String targetHost, final int targetPort, final int timeout) throws Exception { session = SftpClientFactory.createConnection(proxyHost, proxyPort, proxyUser.toCharArray(), proxyPassword.toCharArray(), proxyOptions); channel = (ChannelExec) session.openChannel("exec"); channel.setCommand(String.format(commandFormat, targetHost, targetPort)); channel.connect(timeout); } @Override public InputStream getInputStream() { try { return channel.getInputStream(); } catch (final IOException e) { throw new IllegalStateException("IOException getting the SSH proxy input stream", e); } } @Override public OutputStream getOutputStream() { try { return channel.getOutputStream(); } catch (final IOException e) { throw new IllegalStateException("IOException getting the SSH proxy output stream", e); } } @Override public Socket getSocket() { return null; } }




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