Exposing SslContext for flexibility (e.g. client-side certs, etc)

[mikedilger]

Currently, net::HttpListener::https() takes a certificate and a key, and sets up an SslContext with a lot of assumptions. For example, it sets the DEFAULT cipher list. It also sets SSL_VERIFY_NONE.
This is called by Server::listen_threads(). I'm trying to make changes that allow the caller to pass in an SslContext.

Currently the SSL configuration is declared when the Server is created, by passing a certificate and a key to Server::https(). Unfortunately this scheme will not direclty work with a passed in SslContext, because if an SslContext is setup in the Server struct, it moves when passed on to HttpListener::https(), causing a "use of partially moved value" error. This cannot be solved via clone() because SslContext does not implement clone().

If Server::listen_threads() accepted the SSL information at that point (rather than owning it in it's struct), this would cause a lot of breaking changes.

OTOH, If HttpListener kept a reference to an SslContext (instead of owning it), it would propagate another annoying lifetime parameter over a lot of code.

I don't see a clearly preferable way of implementing this. Given a preferred direction, I'd be happy to make the changes necessary.

[mikedilger]

Another option I thought of: HttpListener could get a separate listen method (where http and https would do everything except the bind step), and then a new method could be created that gets a mutable reference to the SslContext, to be called prior to listen.

Also I forgot to cc @seanmonstar

[seanmonstar]

@mikedilger I'm not sure I follow. In listen_threads, the Server is taken by value. You can move the context out of the Server in this method.

[mikedilger]

self.with_listener(listener, threads) requires both self (Server) and listener. If the context is moved, then 'self' is no longer available. See https://github.com/mikedilger/hyper/tree/ssl_context

[seanmonstar]

Ohhh, I see what you mean. Ok, so the with_listener method takes self, but it only needs to access self.handler. What about creating a private free function with_listener, that the method calls as with_listener(self.handler, listener, threads). Then, listen_threads can skip the internal method, and just move out both the ssl and the handler in the same function. Make sense?

[mikedilger]

I'm glad I asked, because I hadn't thought of that.

I did this in 3 commits. See PR #479