epsv.java

用java写的ftp服务器程序

// $Id: EPSV.java 306698 2005-09-07 10:36:22 +0530 (Wed, 07 Sep 2005) rana_b $
/*
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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.ftpserver.command;

import java.io.IOException;

import org.apache.ftpserver.Command;
import org.apache.ftpserver.FtpDataConnection;
import org.apache.ftpserver.FtpRequestImpl;
import org.apache.ftpserver.FtpWriter;
import org.apache.ftpserver.RequestHandler;

/**
 * The EPSV command requests that a server listen on a data port and
 * wait for a connection.  The EPSV command takes an optional argument.
 * The response to this command includes only the TCP port number of the
 * listening connection.  The format of the response, however, is
 * similar to the argument of the EPRT command.  This allows the same
 * parsing routines to be used for both commands.  In addition, the
 * format leaves a place holder for the network protocol and/or network
 * address, which may be needed in the EPSV response in the future.  The
 * response code for entering passive mode using an extended address
 * MUST be 229.
 * 
 * @author <a href="mailto:[e-mail]">Rana Bhattacharyya</a>
 */
public 
class EPSV implements Command {

    /**
     * Execute command.
     */
    public void execute(RequestHandler handler,
                        FtpRequestImpl request, 
                        FtpWriter out) throws IOException {
        
        // reset state variables
        request.resetState();
        
        // set data connection
        FtpDataConnection dataCon = request.getFtpDataConnection();
        if (!dataCon.setPasvCommand()) {
            out.send(425, "EPSV", null);
            return;   
        }
        
        // get connection info
        int servPort = dataCon.getPort();
        
        // send connection info to client
        String portStr = "|||" + servPort + "|";
        out.send(229, "EPSV", portStr);
    }
}