Add an SSL port to the configuration and advertise this as part of the metadata request.
If the SSL port is configured the socket server will need to add a second Acceptor thread to listen on it. Connections accepted on this port will need to go through the SSL handshake prior to being registered with a Processor for request processing.
SSL requests and responses may need to be wrapped or unwrapped using the SSLEngine that was initialized by the acceptor. This wrapping and unwrapping is very similar to what will need to be done for SASL-based authentication schemes. We should have a uniform interface that covers both of these and we will need to store the instance in the session with the request. The socket server will have to use this object when reading and writing requests. We will need to take care with the FetchRequests as the current FileChannel.transferTo mechanism will be incompatible with wrap/unwrap so we can only use this optimization for unencrypted sockets that don't require userspace translation (wrapping).