Java tutorial
/* * Copyright (c) 2013 Pantheon Technologies s.r.o. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.openflowjava.protocol.impl.core; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ByteToMessageDecoder; import java.util.List; import org.opendaylight.openflowjava.protocol.impl.util.ByteBufUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Decodes incoming messages into message frames. * @author michal.polkorab */ public class OFFrameDecoder extends ByteToMessageDecoder { /** Length of OpenFlow 1.3 header */ public static final byte LENGTH_OF_HEADER = 8; private static final byte LENGTH_INDEX_IN_HEADER = 2; private static final Logger LOGGER = LoggerFactory.getLogger(OFFrameDecoder.class); /** * Constructor of class. */ public OFFrameDecoder() { LOGGER.trace("Creating OFFrameDecoder"); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { LOGGER.warn("Unexpected exception from downstream.", cause); ctx.close(); } @Override protected void decode(ChannelHandlerContext chc, ByteBuf bb, List<Object> list) throws Exception { int readableBytes = bb.readableBytes(); if (readableBytes < LENGTH_OF_HEADER) { LOGGER.debug("skipping bb - too few data for header: " + readableBytes); return; } int length = bb.getUnsignedShort(bb.readerIndex() + LENGTH_INDEX_IN_HEADER); LOGGER.debug("length of actual message: {}", length); if (readableBytes < length) { if (LOGGER.isDebugEnabled()) { LOGGER.debug("skipping bb - too few data for msg: " + readableBytes + " < " + length); LOGGER.debug("bb: " + ByteBufUtils.byteBufToHexString(bb)); } return; } LOGGER.debug("OF Protocol message received, type:{}", bb.getByte(bb.readerIndex() + 1)); ByteBuf messageBuffer = bb.slice(bb.readerIndex(), length); list.add(messageBuffer); messageBuffer.retain(); bb.skipBytes(length); } }