Support Opaque origin headers, serializing it to `null`

[samgiles]

Support Opaque origins:

An internal value, with no serialization it can be recreated from (it is serialized as "null" per ASCII serialization of an origin), for which the only meaningful operation is testing for equality.

https://html.spec.whatwg.org/multipage/browsers.html#concept-origin

[seanmonstar]

Sorry, in what context? The url? The Origin header?

[jdm]

The origin header.

[seanmonstar]

I see. So it can either be null, or the full origin. It seems like any way to make this work with hyper's Origin header would require a breaking change. Since that's the case, my thinking is something like this, for inclusion in v0.11:

pub struct Origin(OriginOrNull);

enum OriginOrNull {
    Origin {
        scheme: String,
        host: Host,
    },
    Null,
}

impl Origin {
    pub fn new<S: Into<String>, H: Into<String>>(scheme: S, hostname: H, port: Option<u16>) -> Origin{
        Origin(OriginOrNull::Origin {
            scheme: scheme.into(),
            host: Host::new(hostname.into(), port),
        })
    }

    pub fn null() -> Origin {
        Origin(OriginOrNull::Null)
    }

    pub fn is_null(&self) -> bool;
    pub fn scheme(&self) -> Option<&str>;
    pub fn hostname(&self) -> Option<&str>;
    pub fn port(&self) -> Option<u16>;
}

Whatcha think?

For servo, if you wish to make use of this right away while keeping to hyper 0.10, you could implement an Origin header in Servo.

[samgiles]

@seanmonstar That looks real similar to the url crate's Origin implementation, since it's a dependency, could we rely on the serialization algorithms implemented there?

Ah, I might implement Header for url::Origin, would be a nice intermediate solution.

[seanmonstar]

Oh I remember this conversation again. We didn't use url::Origin because it requires the port. The header has the port optional.

[seanmonstar]

Thanks to work in #1121, the breaking change required here is done. This would be pretty easy to implement using an internal private enum, as described in #1065 (comment), keeping our use of Cow instead of `String.

[alexeyzab]

Hi there! I'd like to try implementing this.