AbstractFtpCmdPasv.java

/*
 * ------------------------------------------------------------------------------
 * Hermes FTP Server
 * Copyright (c) 2005-2014 Lars Behnke
 * ------------------------------------------------------------------------------
 * 
 * This file is part of Hermes FTP Server.
 * 
 * Hermes FTP Server is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * Hermes FTP Server is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Hermes FTP Server; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ------------------------------------------------------------------------------
 */

package com.apporiented.hermesftp.cmd;

import java.io.IOException;

import com.apporiented.hermesftp.exception.FtpCmdException;
import com.apporiented.hermesftp.exception.FtpIllegalProtocolVersion;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * @author Behnke
 */
public abstract class AbstractFtpCmdPasv extends AbstractFtpCmd {

    private static Log log = LogFactory.getLog(AbstractFtpCmdPasv.class);

    /**
     * {@inheritDoc}
     */
    public void execute() throws FtpCmdException {
        try {

            /* Set up socket provider */
            getCtx().closeSockets();
            DataChannelInfo info;
            SocketProvider socketProvider = new PassiveModeSocketProvider(getCtx(), getPreferredProtocol());
            info = socketProvider.init();
            getCtx().setDataSocketProvider(socketProvider);

            /* Send connection parameters */
            out(createResponseMessage(info.getProtocolIdx(), info.getAddress(), info.getPort()));

            /*
             * Connecting the client (ServerSocket.accept()) is deferred until data channel is
             * needed.
             */

        } catch (FtpIllegalProtocolVersion e) {
            log.error(e.toString());
            msgOut(MSG522);
        } catch (IOException e) {
            log.error(e.toString());
            msgOut(MSG425);
        } catch (RuntimeException e) {
            log.error(e.toString());
            msgOut(MSG501);
        }
    }

    /**
     * {@inheritDoc}
     */
    public boolean isAuthenticationRequired() {
        return true;
    }

    /**
     * Returns the preferred protocol version (1=IPv4, 2=IPv6, 0=undefined).
     * 
     * @return The protocol version.
     */
    protected abstract int getPreferredProtocol();

    /**
     * Returns the reponse string encoding ip address, port and protocol type. Example: 229 Entering
     * Extended Passive Mode (|||6000|).
     * 
     * @param protocol The protocol index (1=IPv4, 2=IPv6).
     * @param addr The address.
     * @param port The port.
     * @return The string encoding the connection data in an appropriate format.
     */
    protected abstract String createResponseMessage(int protocol, String addr, int port);

}