Netty WIP

Implementing ByteBuf backed In/OutPacket first in a separate branch

src/main/java/net/netty/PacketDecoder.java

@@ -0,0 +1,48 @@
+package net.netty;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.ReplayingDecoder;
+import net.mina.MapleCustomEncryption;
+import tools.MapleAESOFB;
+
+import java.util.List;
+
+public class PacketDecoder extends ReplayingDecoder<Void> {
+    private final MapleAESOFB receiveCypher;
+
+    public PacketDecoder(MapleAESOFB receiveCypher) {
+        this.receiveCypher = receiveCypher;
+    }
+
+    @Override
+    protected void decode(ChannelHandlerContext context, ByteBuf in, List<Object> out) {
+        final int header = in.readInt();
+
+        if (!receiveCypher.checkPacket(header)) {
+            throw new InvalidPacketHeaderException("Attempted to decode a packet with an invalid header", header);
+        }
+
+        int packetLength = decodePacketLength(header);
+        byte[] packet = new byte[packetLength];
+        in.readBytes(packet);
+        receiveCypher.crypt(packet);
+        MapleCustomEncryption.decryptData(packet);
+        out.add(packet);
+        // TODO conditionally log the packet
+    }
+
+    /**
+     * @param header Packet header - the first 4 bytes of the packet
+     * @return Packet size in bytes
+     */
+    private static int decodePacketLength(byte[] header) {
+        return (((header[1] ^ header[3]) & 0xFF) << 8) | ((header[0] ^ header[2]) & 0xFF);
+    }
+
+    private static int decodePacketLength(int header) {
+        int length = ((header >>> 16) ^ (header & 0xFFFF));
+        length = ((length << 8) & 0xFF00) | ((length >>> 8) & 0xFF);
+        return length;
+    }
+}