org.evilco.network.rcon.common.codec.RconCodec.java Source code

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Here is the source code for org.evilco.network.rcon.common.codec.RconCodec.java

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/*
 * Copyright 2014 Johannes Donath <johannesd@evil-co.com>
 * 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 org.evilco.network.rcon.common.codec;

import com.google.common.base.Preconditions;
import com.google.common.eventbus.EventBus;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageCodec;
import lombok.*;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.evilco.network.rcon.common.event.packet.PacketReceiveEvent;
import org.evilco.network.rcon.common.event.packet.PacketSendEvent;
import org.evilco.network.rcon.common.event.packet.PacketSentEvent;
import org.evilco.network.rcon.common.packet.IPacket;
import org.evilco.network.rcon.common.packet.PacketWrapper;

import java.nio.ByteOrder;
import java.util.List;

/**
 * @author Johannes Donath <johannesd@evil-co.com>
 * @copyright Copyright (C) 2014 Evil-Co <http://www.evil-co.com>
 */
@AllArgsConstructor
public class RconCodec extends ByteToMessageCodec<PacketWrapper> {

    /**
     * Stores an internal logger instance.
     */
    @Getter(AccessLevel.PROTECTED)
    private static final Logger logger = LogManager.getFormatterLogger(RconCodec.class);

    /**
     * Stores the codec configuration.
     */
    @Getter
    @Setter
    @NonNull
    private ICodecConfiguration configuration;

    /**
     * Stores the event bus.
     */
    @Getter
    @Setter
    @NonNull
    private EventBus eventBus;

    /**
     * {@inheritDoc}
     */
    @Override
    protected void encode(ChannelHandlerContext channelHandlerContext, PacketWrapper packetWrapper, ByteBuf byteBuf)
            throws Exception {
        // set order
        byteBuf = byteBuf.order(ByteOrder.LITTLE_ENDIAN);

        // fire event
        PacketSendEvent event = new PacketSendEvent(packetWrapper);
        this.eventBus.post(event);

        // cancel
        if (event.isCancelled())
            return;
        packetWrapper = event.getPacket();

        // find packetID
        int packetID = this.configuration.getOutboundRegistry().findPacketID(packetWrapper.getPacket());

        // log
        getLogger().debug("Encoding packet of type " + packetWrapper.getPacket().getClass().getName()
                + " (packetID: " + packetID + ") with identifier " + packetWrapper.getIdentifier() + ".");

        // write identifier
        byteBuf.writeInt(packetWrapper.getIdentifier());

        // write packet identifier
        byteBuf.writeInt(packetID);

        // allocate buffer
        ByteBuf buffer = channelHandlerContext.alloc().buffer();

        // write body
        packetWrapper.getPacket().write(buffer);

        // write data
        byteBuf.writeBytes(buffer);

        // write terminator
        buffer.writeBytes(new byte[] { 0x00, 0x00 });

        // fire event
        this.eventBus.post(new PacketSentEvent(packetWrapper));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> objects)
            throws Exception {
        // set order
        byteBuf = byteBuf.order(ByteOrder.LITTLE_ENDIAN);

        // read identifier
        int identifier = byteBuf.readInt();

        // read packet identifier
        int packetID = byteBuf.readInt();

        // allocate buffer
        ByteBuf buffer = channelHandlerContext.alloc().buffer((byteBuf.readableBytes() - 1));

        // read data
        byteBuf.readBytes(buffer, (byteBuf.readableBytes() - 2));

        // read null byte
        Preconditions.checkState((byteBuf.readByte() == 0x00 && byteBuf.readByte() == 0x00),
                "The last byte is not null");
        Preconditions.checkState((byteBuf.readableBytes() == 0), "There is still data left in the packet.");

        // read data
        IPacket packet = this.configuration.getInboundRegistry().createPacketInstance(packetID, buffer);

        // log
        getLogger().debug("Decoded packet of type " + packet.getClass().getName() + " (packetID: " + packetID
                + ", identifier: " + identifier + ").");

        // construct wrapper
        PacketWrapper wrapper = new PacketWrapper(identifier, packet);

        // fire event
        PacketReceiveEvent event = new PacketReceiveEvent(wrapper);
        this.eventBus.post(event);

        // process
        if (!event.isCancelled())
            objects.add(event.getPacket());
        else
            getLogger().debug(
                    "Ignoring packet with identifier %s (packetID: %s, type: %s): Event has been cancelled.",
                    identifier, packetID, packet.getClass());
    }
}