Java tutorial
/* * Copyright (c) 2008-2015, Hazelcast, Inc. All Rights Reserved. * * 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.hazelcast.simulator.protocol.handler; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandler; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import org.apache.log4j.Logger; import static com.hazelcast.simulator.protocol.core.ResponseCodec.isResponse; import static com.hazelcast.simulator.protocol.core.SimulatorMessageCodec.isSimulatorMessage; import static java.lang.String.format; /** * Validates new connections by checking the magic bytes of the first incoming {@link ByteBuf}. * * Removes itself from the channel pipeline after successful validation, since big {@link ByteBuf} * can be split up into several chunks and just the first one contains the magic bytes. */ @ChannelHandler.Sharable public class ConnectionValidationHandler extends ChannelInboundHandlerAdapter { private static final int MINIMUM_BYTE_BUFFER_SIZE = 8; private static final Logger LOGGER = Logger.getLogger(ConnectionValidationHandler.class); @Override public void channelRead(ChannelHandlerContext ctx, Object obj) throws Exception { if (!(obj instanceof ByteBuf)) { return; } ByteBuf buf = (ByteBuf) obj; if (buf.readableBytes() < MINIMUM_BYTE_BUFFER_SIZE) { return; } if (!isSimulatorMessage(buf) && !isResponse(buf)) { LOGGER.warn(format("Invalid connection from %s (no magic bytes found)", ctx.channel().remoteAddress())); ctx.close(); return; } // the connection is valid so we remove this handler and forward the buffer to the pipeline LOGGER.info(format("Valid connection from %s (magic bytes found)", ctx.channel().remoteAddress())); ctx.pipeline().remove(this); ctx.fireChannelRead(obj); } }