org.virtue.network.protocol.event.GameEventDecoder.java Source code

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Here is the source code for org.virtue.network.protocol.event.GameEventDecoder.java

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/**
 * Copyright (c) 2014 Virtue Studios
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.virtue.network.protocol.event;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

import org.virtue.Constants;
import org.virtue.network.event.buffer.InboundBuffer;
import org.virtue.network.protocol.message.GameEventMessage;
import org.virtue.utility.ISAACCipher;

/**
 * @author Kyle Friz
 * @since Sep 5, 2014
 */
public class GameEventDecoder extends ByteToMessageDecoder {

    private ISAACCipher cipher;

    public GameEventDecoder(ISAACCipher cipher) {
        this.cipher = cipher;
    }

    /* (non-Javadoc)
     * @see io.netty.handler.codec.ByteToMessageDecoder#decode(io.netty.channel.ChannelHandlerContext, io.netty.buffer.ByteBuf, java.util.List)
     */
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buf, List<Object> out) throws Exception {
        if (buf.isReadable()) {
            int opcode = buf.readByte() - cipher.nextInt() & 0xFF;
            if (opcode < 0) {
                buf.discardReadBytes();
                return;
            }
            int length = Constants.PACKET_SIZES[opcode];
            if (length < 0) {
                switch (length) {
                case -1:
                    if (buf.isReadable()) {
                        length = buf.readByte() & 0xff;
                    }
                    break;
                case -2:
                    if (buf.readableBytes() >= 2) {
                        length = buf.readShort() & 0xffff;
                    }
                    break;
                default:
                    length = buf.readableBytes();
                    break;
                }
            }
            if (buf.readableBytes() >= length) {
                if (length < 0) {
                    return;
                }
                byte[] payload = new byte[length];
                buf.readBytes(payload, 0, length);
                out.add(new GameEventMessage(opcode, new InboundBuffer(payload)));
            }
        }
    }
}