com.sangupta.swift.netty.proxy.ProxyFrontendHandler.java Source code

Introduction

Here is the source code for com.sangupta.swift.netty.proxy.ProxyFrontendHandler.java

Source

/**
 *
 * swift - Netty based HTTP Server
 * Copyright (c) 2014, Sandeep Gupta
 * 
 * http://sangupta.com/projects/swift
 * 
 * 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.sangupta.swift.netty.proxy;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelOption;

/**
 * 
 * @author sangupta
 *
 */
public class ProxyFrontendHandler extends ChannelInboundHandlerAdapter {

    private final String remoteHost;

    private final int remotePort;

    private volatile Channel outboundChannel;

    public ProxyFrontendHandler(String remoteHost, int remotePort) {
        this.remoteHost = remoteHost;
        this.remotePort = remotePort;
    }

    @Override
    public void channelActive(ChannelHandlerContext channelHandlerContext) {
        final Channel inboundChannel = channelHandlerContext.channel();

        // Start the connection attempt.
        Bootstrap bootstrap = new Bootstrap();

        bootstrap.group(inboundChannel.eventLoop()).channel(channelHandlerContext.channel().getClass())
                .handler(new ProxyBackendHandler(inboundChannel)).option(ChannelOption.AUTO_READ, false);

        ChannelFuture channelFuture = bootstrap.connect(remoteHost, remotePort);
        outboundChannel = channelFuture.channel();

        channelFuture.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) {
                if (future.isSuccess()) {
                    // connection complete start to read first data
                    inboundChannel.read();
                } else {
                    // Close the connection if the connection attempt has failed.
                    inboundChannel.close();
                }
            }
        });
    }

    @Override
    public void channelRead(final ChannelHandlerContext channelHandlerContext, Object message) {
        if (outboundChannel.isActive()) {
            outboundChannel.writeAndFlush(message).addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) {
                    if (future.isSuccess()) {
                        // was able to flush out data, start to read the next chunk
                        channelHandlerContext.channel().read();
                    } else {
                        future.channel().close();
                    }
                }
            });
        }
    }

    @Override
    public void channelInactive(ChannelHandlerContext channelHandlerContext) {
        if (outboundChannel != null) {
            closeOnFlush(outboundChannel);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext channelHandlerContext, Throwable cause) {
        cause.printStackTrace();
        closeOnFlush(channelHandlerContext.channel());
    }

    /**
     * Closes the specified channel after all queued write requests are flushed.
     */
    static void closeOnFlush(Channel channel) {
        if (channel.isActive()) {
            channel.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
        }
    }
}