com.butor.netty.handler.codec.ftp.FtpServerHandler.java Source code

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Here is the source code for com.butor.netty.handler.codec.ftp.FtpServerHandler.java

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/**
 * Copyright (C) 2013 codingtony (t.bussieres@gmail.com)
 *
 * 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 com.butor.netty.handler.codec.ftp;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;

import java.nio.charset.Charset;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.butor.netty.handler.codec.ftp.cmd.CommandExecutionTemplate;

/**
 * Netty handler, partial implementation of <a
 * href="http://tools.ietf.org/html/rfc959">RFC 959
 * "File Transfer Protocol (FTP)"</a> for receiving FTP files. Both active and
 * passive modes are supported.
 * 
 * @author alexkasko Date: 12/27/12
 * 
 * 
 * 
 * Refactoring of the code to make it easier to implement new commands
 * 
 * Effort has been made to make the handler thread so that one instance of FtpServerHandler 
 * could be reused.
 * 
 * @author codingtony Date : 2013-10-17
 * 
 */
public class FtpServerHandler extends SimpleChannelInboundHandler<String> {

    private static final Logger logger = LoggerFactory.getLogger(FtpServerHandler.class);

    private static final Charset ASCII = CharsetUtil.US_ASCII;
    private final CommandExecutionTemplate excutionTemplate;

    /**
     * Constructor for FTP active mode
     * 
     * @param receiver
     *            data receiver implementation
     */
    public FtpServerHandler(CommandExecutionTemplate executionTemplate) {
        this.excutionTemplate = executionTemplate;

    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void channelRead0(ChannelHandlerContext ctx, String payload) throws Exception {
        String message = payload.trim();
        if (message.length() < 3)
            send("501 Syntax error", ctx);
        String cmd = 3 == message.length() ? message.substring(0, 3) : message.substring(0, 4).trim();
        String args = message.length() > cmd.length() ? message.substring(cmd.length() + 1) : "";

        excutionTemplate.executeCommand(ctx, cmd.toUpperCase(), args);

    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        logger.error("Exception caught in FtpServerHandler", cause);
        send("500 Unspecified error", ctx);
    }

    /**
     * {@inheritDoc}
     */

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        send("220 Service ready", ctx);
    }

    private static void send(String response, ChannelHandlerContext ctx) {
        if (logger.isDebugEnabled()) {
            logger.debug("<- " + response);
        }
        String line = response + "\r\n";
        byte[] data = line.getBytes(ASCII);
        ctx.channel().writeAndFlush(Unpooled.wrappedBuffer(data));
    }

}