Motivation:
SslHandler owns the responsibility to flush non-application data
(e.g. handshake, renegotiation, etc.) to the socket. However when
TCP Fast Open is supported but the client_hello cannot be written
in the SYN the client_hello may not always be flushed. SslHandler
may not wrap/flush previously written/flushed data in the event
it was not able to be wrapped due to NEED_UNWRAP state being
encountered in wrap (e.g. peer initiated renegotiation).
Modifications:
- SslHandler to flush in channelActive() if TFO is enabled and
the client_hello cannot be written in the SYN.
- SslHandler to wrap application data after non-application data
wrap and handshake status is FINISHED.
- SocketSslEchoTest only flushes when writes are done, and waits
for the handshake to complete before writing.
Result:
SslHandler flushes handshake data for TFO, and previously flushed
application data after peer initiated renegotiation finishes.