Java example source code file (ProxyServer.java)

This example Java source code file (ProxyServer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

backendhandler, bootstrap, exception, inetsocketaddress, net, network, object, override, proxyserver, queue, serverbootstrap, serversocketchannel, simplechannelinboundhandler, string, testmode, threading, threads, throwable, util

The ProxyServer.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you 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 io.netty.handler.proxy;

import io.netty.bootstrap.Bootstrap;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoop;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.ServerSocketChannel;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.util.CharsetUtil;
import io.netty.util.NetUtil;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.LinkedBlockingQueue;

abstract class ProxyServer {

    protected final InternalLogger logger = InternalLoggerFactory.getInstance(getClass());

    private final ServerSocketChannel ch;
    private final Queue<Throwable> recordedExceptions = new LinkedBlockingQueue();
    protected final TestMode testMode;
    protected final String username;
    protected final String password;
    protected final InetSocketAddress destination;

    /**
     * Starts a new proxy server with disabled authentication for testing purpose.
     *
     * @param useSsl {@code true} if and only if implicit SSL is enabled
     * @param testMode the test mode
     * @param destination the expected destination. If the client requests proxying to a different destination, this
     * server will reject the connection request.
     */
    protected ProxyServer(boolean useSsl, TestMode testMode, InetSocketAddress destination) {
        this(useSsl, testMode, destination, null, null);
    }

    /**
     * Starts a new proxy server with disabled authentication for testing purpose.
     *
     * @param useSsl {@code true} if and only if implicit SSL is enabled
     * @param testMode the test mode
     * @param username the expected username. If the client tries to authenticate with a different username, this server
     * will fail the authentication request.
     * @param password the expected password. If the client tries to authenticate with a different password, this server
     * will fail the authentication request.
     * @param destination the expected destination. If the client requests proxying to a different destination, this
     * server will reject the connection request.
     */
    protected ProxyServer(
            final boolean useSsl, TestMode testMode,
            InetSocketAddress destination, String username, String password) {

        this.testMode = testMode;
        this.destination = destination;
        this.username = username;
        this.password = password;

        ServerBootstrap b = new ServerBootstrap();
        b.channel(NioServerSocketChannel.class);
        b.group(ProxyHandlerTest.group);
        b.childHandler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
                ChannelPipeline p = ch.pipeline();
                if (useSsl) {
                    p.addLast(ProxyHandlerTest.serverSslCtx.newHandler(ch.alloc()));
                }

                configure(ch);
            }
        });

        ch = (ServerSocketChannel) b.bind(NetUtil.LOCALHOST, 0).syncUninterruptibly().channel();
    }

    public final InetSocketAddress address() {
        return new InetSocketAddress(NetUtil.LOCALHOST, ch.localAddress().getPort());
    }

    protected abstract void configure(SocketChannel ch) throws Exception;

    final void recordException(Throwable t) {
        logger.warn("Unexpected exception from proxy server:", t);
        recordedExceptions.add(t);
    }

    /**
     * Clears all recorded exceptions.
     */
    public final void clearExceptions() {
        recordedExceptions.clear();
    }

    /**
     * Logs all recorded exceptions and raises the last one so that the caller can fail.
     */
    public final void checkExceptions() {
        Throwable t;
        for (;;) {
            t = recordedExceptions.poll();
            if (t == null) {
                break;
            }

            logger.warn("Unexpected exception:", t);
        }

        if (t != null) {
            PlatformDependent.throwException(t);
        }
    }

    public final void stop() {
        ch.close();
    }

    protected abstract class IntermediaryHandler extends SimpleChannelInboundHandler<Object> {

        private final Queue<Object> received = new ArrayDeque