Auto merge of #9608 - nikkisquared:implement_http_redirect_fetch, r=jdm

Implementation of HTTP Redirect Fetch step

I've made a first draft of a complete implementation of HTTP Redirect Fetch, most of which is just refactored out of HTTP Fetch. I've also made some minor changes in a few other steps, all collected in the second commit, based on recent changes to the Fetch Standard. Since HTTP Redirect Fetch is so new, I figured now would be a fine time to make those other changes.

The biggest thing on my mind right now is how the spec says[1] "This algorithm will be used by HTML's "navigate" algorithm in addition to HTTP fetch above." This makes me think that this function, as well as HTTP Fetch, need to public, or at least have a public-facing function- since each Fetch function takes an Rc<Request>, which might be weird to require callers to supply.

[1] https://fetch.spec.whatwg.org/#http-redirect-fetch

<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.svg" height="40" alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/9608)
<!-- Reviewable:end -->

tests/unit/net/fetch.rs

@@ -5,6 +5,7 @@
 use hyper::header::{AccessControlAllowHeaders, AccessControlAllowOrigin};
 use hyper::header::{CacheControl, ContentLanguage, ContentType, Expires, LastModified};
 use hyper::header::{Headers, HttpDate, Location, SetCookie, Pragma};
+use hyper::method::Method;
 use hyper::server::{Handler, Listening, Server};
 use hyper::server::{Request as HyperRequest, Response as HyperResponse};
 use hyper::status::StatusCode;
@@ -14,6 +15,7 @@ use net_traits::request::{Context, RedirectMode, Referer, Request, RequestMode};
 use net_traits::response::{CacheState, Response, ResponseBody, ResponseType};
 use std::cell::Cell;
 use std::rc::Rc;
+use std::sync::{Arc, Mutex, mpsc};
 use time::{self, Duration};
 use unicase::UniCase;
 use url::{Origin, OpaqueOrigin, Url};
@@ -324,3 +326,98 @@ fn test_fetch_redirect_count_failure() {
         _ => { }
     };
 }
+
+fn test_fetch_redirect_updates_method_runner(tx: mpsc::Sender<bool>, status_code: StatusCode, method: Method) {
+
+    let handler_method = method.clone();
+    let handler_tx = Arc::new(Mutex::new(tx));
+
+    let handler = move |request: HyperRequest, mut response: HyperResponse| {
+
+        let redirects = match request.uri {
+            RequestUri::AbsolutePath(url) =>
+                url.split("/").collect::<String>().parse::<u32>().unwrap_or(0),
+            RequestUri::AbsoluteUri(url) =>
+                url.path().unwrap().last().unwrap().split("/").collect::<String>().parse::<u32>().unwrap_or(0),
+            _ => panic!()
+        };
+
+        let mut test_pass = true;
+
+        if redirects == 0 {
+
+            *response.status_mut() = StatusCode::TemporaryRedirect;
+            response.headers_mut().set(Location("1".to_owned()));
+
+        } else if redirects == 1 {
+
+            // this makes sure that the request method does't change from the wrong status code
+            if handler_method != Method::Get && request.method == Method::Get {
+                test_pass = false;
+            }
+            *response.status_mut() = status_code;
+            response.headers_mut().set(Location("2".to_owned()));
+
+        } else if request.method != Method::Get {
+            test_pass = false;
+        }
+
+        // the first time this handler is reached, nothing is being tested, so don't send anything
+        if redirects > 0 {
+            handler_tx.lock().unwrap().send(test_pass).unwrap();
+        }
+
+    };
+
+    let (mut server, url) = make_server(handler);
+    let origin = url.origin();
+
+    let mut request = Request::new(url, Context::Fetch, origin, false);
+    request.referer = Referer::NoReferer;
+    *request.method.borrow_mut() = method;
+    let wrapped_request = Rc::new(request);
+
+    let _ = fetch(wrapped_request, false);
+    let _ = server.close();
+}
+
+#[test]
+fn test_fetch_redirect_updates_method() {
+
+    let (tx, rx) = mpsc::channel();
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::MovedPermanently, Method::Post);
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.recv().unwrap(), true);
+    // make sure the test doesn't send more data than expected
+    assert_eq!(rx.try_recv().is_err(), true);
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::Found, Method::Post);
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.try_recv().is_err(), true);
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::SeeOther, Method::Get);
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.try_recv().is_err(), true);
+
+    let extension = Method::Extension("FOO".to_owned());
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::MovedPermanently, extension.clone());
+    assert_eq!(rx.recv().unwrap(), true);
+    // for MovedPermanently and Found, Method should only be changed if it was Post
+    assert_eq!(rx.recv().unwrap(), false);
+    assert_eq!(rx.try_recv().is_err(), true);
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::Found, extension.clone());
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.recv().unwrap(), false);
+    assert_eq!(rx.try_recv().is_err(), true);
+
+    test_fetch_redirect_updates_method_runner(tx.clone(), StatusCode::SeeOther, extension.clone());
+    assert_eq!(rx.recv().unwrap(), true);
+    // for SeeOther, Method should always be changed, so this should be true
+    assert_eq!(rx.recv().unwrap(), true);
+    assert_eq!(rx.try_recv().is_err(), true);
+}