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	QByteArray block;
	QDataStream out(&block, QIODevice::WriteOnly);

	out << (quint32)0;
	out << Cmd::SET_DATA;
	out << data;

	out.device()->seek(0);
	out << (quint32)(block.size() - sizeof(quint32));

	socket.write(block);
	socket.flush();
	socket.waitForBytesWritten(); // exception here