public void execLogoff() throws IOException {
        int data_size = NumUtil.readInteger(In);
        byte[] spell = new byte[data_size];
        int spell_read = BuffUtil.readStream(In, spell, 0, data_size);
        if(spell_read != data_size){
            Logger.debug("NGXgُł@UserRequest#execLogoff");
            throw new IOException("NGXgُł@UserRequest#execLogoff");
        }
        ReqUtil.writeHeader(Out,false,false,4);
        if(User.logoff(spell)){
            NumUtil.writeInteger(Out,HadukiCode.LOGOFF_SUCCESS);
        }else{
            NumUtil.writeInteger(Out,HadukiCode.LOGOFF_FAILURE);
        }
    }