Motivation:
ReferenceCountedOpenSslEngine may unwrap data and complete the handshake
in a single unwrap() call. However it may return HanshakeStatus of
HandshakeStatus of NEED_UNWRAP instead of FINISHED. This may result in
the SslHandler sending the unwrapped data up the pipeline before
notifying that the handshake has completed, and result in out-of-order
events.
Modifications:
- if ReferenceCountedOpenSslEngine handshake status is NEED_UNWRAP and
produced data, or NEED_WRAP and consumed some data, we should call
handshake() to get the current state.
Result:
ReferenceCountedOpenSslEngine correctly indicates when the handshake has
finished if at the same time data was produced or consumed.