Java tutorial
/* * 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.channel.ChannelHandlerContext; import io.netty.channel.ChannelPipeline; import io.netty.handler.codec.socksx.v4.DefaultSocks4CommandRequest; import io.netty.handler.codec.socksx.v4.Socks4ClientDecoder; import io.netty.handler.codec.socksx.v4.Socks4ClientEncoder; import io.netty.handler.codec.socksx.v4.Socks4CommandResponse; import io.netty.handler.codec.socksx.v4.Socks4CommandStatus; import io.netty.handler.codec.socksx.v4.Socks4CommandType; import java.net.InetSocketAddress; import java.net.SocketAddress; public final class Socks4ProxyHandler extends ProxyHandler { private static final String PROTOCOL = "socks4"; private static final String AUTH_USERNAME = "username"; private final String username; private String decoderName; private String encoderName; public Socks4ProxyHandler(SocketAddress proxyAddress) { this(proxyAddress, null); } public Socks4ProxyHandler(SocketAddress proxyAddress, String username) { super(proxyAddress); if (username != null && username.isEmpty()) { username = null; } this.username = username; } @Override public String protocol() { return PROTOCOL; } @Override public String authScheme() { return username != null ? AUTH_USERNAME : AUTH_NONE; } public String username() { return username; } @Override protected void addCodec(ChannelHandlerContext ctx) throws Exception { ChannelPipeline p = ctx.pipeline(); String name = ctx.name(); Socks4ClientDecoder decoder = new Socks4ClientDecoder(); p.addBefore(name, null, decoder); decoderName = p.context(decoder).name(); encoderName = decoderName + ".encoder"; p.addBefore(name, encoderName, Socks4ClientEncoder.INSTANCE); } @Override protected void removeEncoder(ChannelHandlerContext ctx) throws Exception { ChannelPipeline p = ctx.pipeline(); p.remove(encoderName); } @Override protected void removeDecoder(ChannelHandlerContext ctx) throws Exception { ChannelPipeline p = ctx.pipeline(); p.remove(decoderName); } @Override protected Object newInitialMessage(ChannelHandlerContext ctx) throws Exception { InetSocketAddress raddr = destinationAddress(); String rhost; if (raddr.isUnresolved()) { rhost = raddr.getHostString(); } else { rhost = raddr.getAddress().getHostAddress(); } return new DefaultSocks4CommandRequest(Socks4CommandType.CONNECT, rhost, raddr.getPort(), username != null ? username : ""); } @Override protected boolean handleResponse(ChannelHandlerContext ctx, Object response) throws Exception { final Socks4CommandResponse res = (Socks4CommandResponse) response; final Socks4CommandStatus status = res.status(); if (status == Socks4CommandStatus.SUCCESS) { return true; } throw new ProxyConnectException(exceptionMessage("status: " + status)); } }