if ( ( b = this.in.read() ) == -1 )
                return null;
            this.sbuf[ 35 ] = (byte) b;
        }

        /*
         * Unless key returned is null or invalid Transport.loop() always
         * calls doRecv() after and no one else but the transport thread
         * should call doRecv(). Therefore it is ok to expect that the data
         * in sbuf will be preserved for copying into BUF in doRecv().