short extraLength = headerBuffer.readUnsignedByte();
short dataType = headerBuffer.readUnsignedByte(); // unused
short reserved = headerBuffer.readShort(); // unused
int totalBodyLength = headerBuffer.readInt();
int opaque = headerBuffer.readInt();
long cas = headerBuffer.readLong();
// we want the whole of totalBodyLength; otherwise, keep waiting.
if (channelBuffer.readableBytes() < totalBodyLength) {
channelBuffer.resetReaderIndex();
return null;