Java tutorial
/* * Copyright 2015 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.codec.socksx; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelPipeline; import io.netty.handler.codec.ByteToMessageDecoder; import io.netty.handler.codec.socksx.v4.Socks4ServerDecoder; import io.netty.handler.codec.socksx.v4.Socks4ServerEncoder; import io.netty.handler.codec.socksx.v5.Socks5AddressEncoder; import io.netty.handler.codec.socksx.v5.Socks5InitialRequestDecoder; import io.netty.handler.codec.socksx.v5.Socks5ServerEncoder; import io.netty.util.internal.ObjectUtil; import io.netty.util.internal.logging.InternalLogger; import io.netty.util.internal.logging.InternalLoggerFactory; import java.util.List; /** * Detects the version of the current SOCKS connection and initializes the pipeline with * {@link Socks4ServerDecoder} or {@link Socks5InitialRequestDecoder}. */ public class SocksPortUnificationServerHandler extends ByteToMessageDecoder { private static final InternalLogger logger = InternalLoggerFactory .getInstance(SocksPortUnificationServerHandler.class); private final Socks5ServerEncoder socks5encoder; /** * Creates a new instance with the default configuration. */ public SocksPortUnificationServerHandler() { this(Socks5ServerEncoder.DEFAULT); } /** * Creates a new instance with the specified {@link Socks5ServerEncoder}. * This constructor is useful when a user wants to use an alternative {@link Socks5AddressEncoder}. */ public SocksPortUnificationServerHandler(Socks5ServerEncoder socks5encoder) { this.socks5encoder = ObjectUtil.checkNotNull(socks5encoder, "socks5encoder"); } @Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception { final int readerIndex = in.readerIndex(); if (in.writerIndex() == readerIndex) { return; } ChannelPipeline p = ctx.pipeline(); final byte versionVal = in.getByte(readerIndex); SocksVersion version = SocksVersion.valueOf(versionVal); switch (version) { case SOCKS4a: logKnownVersion(ctx, version); p.addAfter(ctx.name(), null, Socks4ServerEncoder.INSTANCE); p.addAfter(ctx.name(), null, new Socks4ServerDecoder()); break; case SOCKS5: logKnownVersion(ctx, version); p.addAfter(ctx.name(), null, socks5encoder); p.addAfter(ctx.name(), null, new Socks5InitialRequestDecoder()); break; default: logUnknownVersion(ctx, versionVal); in.skipBytes(in.readableBytes()); ctx.close(); return; } p.remove(this); } private static void logKnownVersion(ChannelHandlerContext ctx, SocksVersion version) { logger.debug("{} Protocol version: {}({})", ctx.channel(), version); } private static void logUnknownVersion(ChannelHandlerContext ctx, byte versionVal) { if (logger.isDebugEnabled()) { logger.debug("{} Unknown protocol version: {}", ctx.channel(), versionVal & 0xFF); } } }