* in dst, together with the Result. dst may have been re-allocated
* so caller should check the returned value in Result
* If handshaking is in progress then, possibly no data is returned
*/
WrapperResult recvAndUnwrap(ByteBuffer dst) throws IOException {
Status status = Status.OK;
WrapperResult r = new WrapperResult();
r.buf = dst;
if (closed) {
throw new IOException ("Engine is closed");
}