20170617_7.rs

struct Referer {
    url:String
}

impl<'a, 'r> FromRequest<'a, 'r> for Referer {
    type Error = ();

    fn from_request(request: &'a Request<'r>) -> Outcome<Referer, ()> {
        match request.headers().get_one("Referer") {
            Some(r) => Success(Referer { url:r.into() }),
            None => Forward(()),
        }
    }
}