pasv.java

用java写的ftp服务器程序

// $Id: PASV.java 306757 2005-10-06 11:33:33 +0530 (Thu, 06 Oct 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 java.net.InetAddress;

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;
import org.apache.ftpserver.ftplet.FtpException;

/**
 * <code>PASV &lt;CRLF&gt;</code><br>
 *
 * This command requests the server-DTP to "listen" on a data
 * port (which is not its default data port) and to wait for a
 * connection rather than initiate one upon receipt of a
 * transfer command.  The response to this command includes the
 * host and port address this server is listening on.
 * 
 * @author <a href="mailto:[e-mail]">Rana Bhattacharyya</a>
 */
public 
class PASV implements Command {

    /**
     * Execute command
     */
    public void execute(RequestHandler handler, 
                        FtpRequestImpl request, 
                        FtpWriter out) throws IOException, FtpException {
        
        // reset state variables
        request.resetState();
        
        // set data connection
        FtpDataConnection dataCon = request.getFtpDataConnection();
        if (!dataCon.setPasvCommand()) {
            out.send(425, "PASV", null);
            return;   
        }
        
        // get connection info
        InetAddress servAddr = dataCon.getInetAddress();
        int servPort = dataCon.getPort();
        
        // send connection info to client
        String addrStr = servAddr.getHostAddress().replace( '.', ',' ) + ',' + (servPort>>8) + ',' + (servPort&0xFF);
        out.send(227, "PASV", addrStr);
    }
}