TLS Handshake State
SSL/TLS Handshake State
Return true iff we have received a particular message already
| HandshakeType handshake_msg | the message type | 
Confirm that we were expecting this message type
| HandshakeType handshake_msg | the message type | 
Record that we are expecting a particular message type next
| HandshakeType handshake_msg | the message type |