net.ieldor.network.codec.buf.PacketBufDecoder.java Source code

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Here is the source code for net.ieldor.network.codec.buf.PacketBufDecoder.java

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/*
 * This file is part of Ieldor.
 *
 * Ieldor is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Ieldor is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Ieldor.  If not, see <http://www.gnu.org/licenses/>.
 */
package net.ieldor.network.codec.buf;

import java.io.IOException;

import net.ieldor.config.IncommingOpcode;
import net.ieldor.io.Packet;
import net.ieldor.io.Packet.PacketType;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

/**
 * An {@link ByteToMessageDecoder} that is used to decode incoming packets from the
 * client.
 * 
 * @author Thomas Le Godais <thomaslegodais@live.com>
 * 
 */
public class PacketBufDecoder extends ByteToMessageDecoder<Packet> {

    public static final int[] SIZES = IncommingOpcode.getPacketSizes();

    private enum State {
        READ_OPCODE, READ_SIZE, READ_PAYLOAD
    }

    private State state = State.READ_OPCODE;
    private boolean variable;
    private int opcode, size;

    @Override
    public Packet decode(ChannelHandlerContext ctx, ByteBuf buf) throws Exception {
        if (state == State.READ_OPCODE) {
            if (!buf.readable())
                return null;

            opcode = (buf.readUnsignedByte()) & 0xFF;
            if (opcode > SIZES.length || opcode < 0) {
                System.out.println("Invalid opcode received: " + opcode);
                return null;
            }
            size = SIZES[opcode];

            if (size == -3) {
                System.out.println("Invalid packet size for: " + opcode);
                return null;
                //throw new IOException("Illegal opcode " + opcode + ".");
            }

            variable = size == -1;
            state = variable ? State.READ_SIZE : State.READ_PAYLOAD;
        }

        if (state == State.READ_SIZE) {
            if (!buf.readable()) {
                return null;
            }

            size = buf.readUnsignedByte();
            state = State.READ_PAYLOAD;
        }

        if (state == State.READ_PAYLOAD) {
            if (buf.readableBytes() < size)
                return null;

            ByteBuf payload = buf.readBytes(size);
            state = State.READ_OPCODE;

            //System.out.println("Received packet: opcode="+opcode+", size="+size);

            return new Packet(opcode, variable ? PacketType.BYTE : PacketType.FIXED, payload);
        }

        throw new IllegalStateException();
    }

}