/**
     * @return
     * @throws IOException
     */
    private int negotiateWrite ( CommonServerMessageBlockRequest req, boolean setmid ) throws IOException {
        if ( setmid ) {
            makeKey(req);
        }
        else {
            req.setMid(0);
            this.mid.set(1);
        }
        int n = req.encode(this.sbuf, 4);