Start an asynchronous SSL handshake.
template< typename HandshakeHandler> void-or-deduced async_handshake( handshake_type type, HandshakeHandler handler);
This function is used to asynchronously perform an SSL handshake on the stream. This function call always returns immediately.
The type of handshaking to be performed, i.e. as a client or as a server.
The handler to be called when the handshake operation completes. Copies will be made of the handler as required. The equivalent function signature of the handler must be:
void handler( const boost::system::error_code& error // Result of operation. );