Allow to configure websocket handshake interceptors

[oscararias]

Hi!

When working with subscriptions it would be useful to configure handshake interceptors like HttpSessionHandshakeInterceptor or other custom interceptors.

As for now, the only way I found of doing so was to opt-out of the whole websocket autoconfiguration. However, this could be achieved with a small change in the WebsocketAutoconfiguration class.

I did a very simple implementation that would perfectly work out for me, you can see it in this commit. Basically, I added a HandshakeInterceptorsFactory interface that can be implemented, if needed, to register interceptors.

I think this would be a good enhancement to the websocket autoconfiguration feature. Let me know your opinions.

Regards

[iamlothian]

I'm looking into something similar.

I am trying to secure web socket requests by introspecting the authorization header sent on the connection_init request and then populate the DefaultGlobalContext with the user session info.

'{"type":"connection_init","payload":{"Authorization":"bearer CbFKMklFnqKzj6xEFbw62y5EL9I"}}'

This is proving to be challenging, as I have to override a lot of the auto config beans to do this, which will make upgrading SPQR later difficult.