port.java

用java写的ftp服务器程序

// $Id: PORT.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 java.net.UnknownHostException;
import java.util.StringTokenizer;

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

/**
 * <code>PORT &lt;SP&gt; <host-port> &lt;CRLF&gt;</code><br>
 *
 * The argument is a HOST-PORT specification for the data port
 * to be used in data connection.  There are defaults for both
 * the user and server data ports, and under normal
 * circumstances this command and its reply are not needed.  If
 * this command is used, the argument is the concatenation of a
 * 32-bit internet host address and a 16-bit TCP port address.
 * This address information is broken into 8-bit fields and the
 * value of each field is transmitted as a decimal number (in
 * character string representation).  The fields are separated
 * by commas.  A port command would be:
 *
 *   PORT h1,h2,h3,h4,p1,p2
 * 
 * where h1 is the high order 8 bits of the internet host address.
 * 
 * @author <a href="mailto:[e-mail]">Rana Bhattacharyya</a>
 */
public 
class PORT implements Command {

    /**
     * Execute command.
     */
    public void execute(RequestHandler handler,
                        FtpRequestImpl request, 
                        FtpWriter out) throws IOException {
        
        // reset state variables
        request.resetState();
        
        // argument check
        if(!request.hasArgument()) {
            out.send(501, "PORT", null);
            return;  
        }
        
        StringTokenizer st = new StringTokenizer(request.getArgument(), ",");
        if(st.countTokens() != 6) {
            out.send(510, "PORT", null);
            return;
        }
        
        // is port enabled
        if(!handler.getConfig().getDataConnectionConfig().isPortEnabled()) {
            out.send(510, "PORT.disabled", null);
            return;
        } 
        
        // get data server
        String dataSrvName = st.nextToken() + '.' + st.nextToken() + '.' +
        st.nextToken() + '.' + st.nextToken();
        InetAddress dataAddr = null;
        try {
            dataAddr = InetAddress.getByName(dataSrvName);
        }
        catch(UnknownHostException ex) {
            out.send(553, "PORT.host", null);
            return;
        }
        
        // check IP
        if(handler.getConfig().getDataConnectionConfig().isPortIpCheck()) {
            InetAddress clientAddr = handler.getRequest().getRemoteAddress();
            if(!dataAddr.equals(clientAddr)) {
                out.send(510, "PORT.mismatch", null);
                return;
            }
        }
        
        // get data server port
        int dataPort = 0;
        try {
            int hi = Integer.parseInt(st.nextToken());
            int lo = Integer.parseInt(st.nextToken());
            dataPort = (hi << 8) | lo;     
        }
        catch(NumberFormatException ex) {
            out.send(552, "PORT.invalid", null); 
            return; 
        }
        
        request.getFtpDataConnection().setPortCommand(dataAddr, dataPort);
        out.send(200, "PORT", null);
    }
    
}