com.vethrfolnir.game.network.mu.MuCyperDecoder.java Source code

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Here is the source code for com.vethrfolnir.game.network.mu.MuCyperDecoder.java

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/**
 * Copyright (C) 2013-2014 Project-Vethrfolnir
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.vethrfolnir.game.network.mu;

import static com.vethrfolnir.game.network.mu.crypt.MuDecoder.DecodePacket;
import static com.vethrfolnir.game.network.mu.crypt.MuDecoder.DecodeXor32;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

import com.vethrfolnir.logging.MuLogger;

/**
 * @author Vlad
 *
 */
public final class MuCyperDecoder extends ByteToMessageDecoder {

    private static final MuLogger _log = MuLogger.getLogger(MuCyperDecoder.class);

    /* (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 in, List<Object> out) throws Exception {

        if (!in.isReadable()) {
            MuClient client = ctx.channel().attr(MuClient.ClientKey).get();
            _log.warn("Client[" + client + "] sent an empty packet!");

            return; //XXX: is it critical?
        }

        if (in.readableBytes() < 3) {
            return; // come back later
        }

        in.markReaderIndex();

        int opcode = in.readUnsignedByte();

        int lengthAt = 0;
        switch (opcode) {
        case 0xc1:
        case 0xc3:
            lengthAt = 1;
            break;
        case 0xc2:
        case 0xc4:
            lengthAt = 2;
            break;
        }

        //in.markReaderIndex();
        int rez = lengthAt > 1 ? in.readShort() : in.readUnsignedByte();
        in.resetReaderIndex();

        //System.out.println("1 Size[point="+(lengthAt > 1 ? "Short" : "Unsigned byte")+"]: "+rez+" opcode "+Integer.toHexString(opcode & 0xFF));
        if (in.readableBytes() < rez) {
            in.resetReaderIndex();
            return;
        }

        int header = in.getUnsignedByte(0);
        if (header == 0xC1 || header == 0xC2) {
            ByteBuf buff = ctx.alloc().heapBuffer(rez);
            in.readBytes(buff);
            out.add(DecodeXor32(buff));
        } else {
            out.add(DecodePacket(in));
        }
    }
}