WinTLSSession buffers received decrypted data into its own buffer. If
read is requested, it copies the data from its buffer. But if
requested buffer size is less than decrypted buffer, some of the data
is left in the buffer. Previously, we had no facility to check the
existence of this pending data. If this data is the last requested
data from remote server, we may end up waiting for read event even if
we have already data in our buffer, which may cause hang. This commit
fixes this issue by introducing function to return the buffered length
in TLSSession. SocketCore also provides the same function, which
delegates to TLSSession object.
Make it clear that TLS_WANT_READ must be returned if underlying
SSL/TLS lib does not indicate I/O direction. This is because
SocketCore sets wantRead_ = true when TLS_WANT_READ is returned and
otherwise sets wantWrite_ = true. We only want to set wantWrite_ =
true iff we have some pending data to send.
Nils Maier