Fix setting content-length: 0 for HEAD responses with compression middleware (#755)

* Fix getting `content-length` for `chunked` responses

Fixes #747

* changelog

* Fix `cargo deny bans`

https://github.com/tokio-rs/axum/pull/753 will fix things properly

axum/CHANGELOG.md

@@ -54,6 +54,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **fixed:** Set `Allow` header when responding with `405 Method Not Allowed` ([#733])
 - **fixed:** Correctly set the `Content-Length` header for response to `HEAD`
   requests ([#734])
+- **fixed:** Fix wrong `content-length` for `HEAD` requests to endpoints that returns chunked
+  responses ([#755])
 
 [#644]: https://github.com/tokio-rs/axum/pull/644
 [#665]: https://github.com/tokio-rs/axum/pull/665
@@ -62,6 +64,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#719]: https://github.com/tokio-rs/axum/pull/719
 [#733]: https://github.com/tokio-rs/axum/pull/733
 [#734]: https://github.com/tokio-rs/axum/pull/734
+[#755]: https://github.com/tokio-rs/axum/pull/755
 
 # 0.4.4 (13. January, 2022)
 

axum/src/routing/future.rs

@@ -1,21 +1,3 @@
 //! Future types.
 
-use crate::response::Response;
-use std::convert::Infallible;
-
 pub use super::{into_make_service::IntoMakeServiceFuture, route::RouteFuture};
-
-opaque_future! {
-    /// Response future for [`Router`](super::Router).
-    pub type RouterFuture<B> = RouteFuture<B, Infallible>;
-}
-
-impl<B> RouterFuture<B> {
-    pub(super) fn from_future(future: RouteFuture<B, Infallible>) -> Self {
-        Self::new(future)
-    }
-
-    pub(super) fn from_response(response: Response) -> Self {
-        Self::new(RouteFuture::from_response(response))
-    }
-}

axum/src/routing/method_routing.rs

@@ -983,7 +983,7 @@ where
             ) => {
                 if $method == Method::$method_variant {
                     if let Some(svc) = $svc {
-                        return RouteFuture::from_future(svc.0.clone().oneshot($req))
+                        return RouteFuture::from_future(svc.oneshot_inner($req))
                             .strip_body($method == Method::HEAD);
                     }
                 }
@@ -1018,11 +1018,9 @@ where
         call!(req, method, TRACE, trace);
 
         let future = match fallback {
-            Fallback::Default(fallback) => {
-                RouteFuture::from_future(fallback.0.clone().oneshot(req))
-                    .strip_body(method == Method::HEAD)
-            }
-            Fallback::Custom(fallback) => RouteFuture::from_future(fallback.0.clone().oneshot(req))
+            Fallback::Default(fallback) => RouteFuture::from_future(fallback.oneshot_inner(req))
+                .strip_body(method == Method::HEAD),
+            Fallback::Custom(fallback) => RouteFuture::from_future(fallback.oneshot_inner(req))
                 .strip_body(method == Method::HEAD),
         };
 

axum/src/routing/mod.rs

@@ -1,6 +1,6 @@
 //! Routing between [`Service`]s and handlers.
 
-use self::{future::RouterFuture, not_found::NotFound};
+use self::{future::RouteFuture, not_found::NotFound};
 use crate::{
     body::{boxed, Body, Bytes, HttpBody},
     extract::connect_info::{Connected, IntoMakeServiceWithConnectInfo},
@@ -396,7 +396,11 @@ where
     }
 
     #[inline]
-    fn call_route(&self, match_: matchit::Match<&RouteId>, mut req: Request<B>) -> RouterFuture<B> {
+    fn call_route(
+        &self,
+        match_: matchit::Match<&RouteId>,
+        mut req: Request<B>,
+    ) -> RouteFuture<B, Infallible> {
         let id = *match_.value;
         req.extensions_mut().insert(id);
 
@@ -440,11 +444,10 @@ where
             .expect("no route for id. This is a bug in axum. Please file an issue")
             .clone();
 
-        let future = match &mut route {
+        match &mut route {
             Endpoint::MethodRouter(inner) => inner.call(req),
             Endpoint::Route(inner) => inner.call(req),
-        };
-        RouterFuture::from_future(future)
+        }
     }
 
     fn panic_on_matchit_error(&self, err: matchit::InsertError) {
@@ -465,7 +468,7 @@ where
 {
     type Response = Response;
     type Error = Infallible;
-    type Future = RouterFuture<B>;
+    type Future = RouteFuture<B, Infallible>;
 
     #[inline]
     fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
@@ -496,15 +499,11 @@ where
                         with_path(req.uri(), &format!("{}/", path))
                     };
                     let res = Redirect::permanent(redirect_to);
-                    RouterFuture::from_response(res.into_response())
+                    RouteFuture::from_response(res.into_response())
                 } else {
                     match &self.fallback {
-                        Fallback::Default(inner) => {
-                            RouterFuture::from_future(inner.clone().call(req))
-                        }
-                        Fallback::Custom(inner) => {
-                            RouterFuture::from_future(inner.clone().call(req))
-                        }
+                        Fallback::Default(inner) => inner.clone().call(req),
+                        Fallback::Custom(inner) => inner.clone().call(req),
                     }
                 }
             }

axum/src/routing/route.rs

@@ -25,7 +25,7 @@ use tower_service::Service;
 ///
 /// You normally shouldn't need to care about this type. It's used in
 /// [`Router::layer`](super::Router::layer).
-pub struct Route<B = Body, E = Infallible>(pub(crate) BoxCloneService<Request<B>, Response, E>);
+pub struct Route<B = Body, E = Infallible>(BoxCloneService<Request<B>, Response, E>);
 
 impl<B, E> Route<B, E> {
     pub(super) fn new<T>(svc: T) -> Self
@@ -35,6 +35,13 @@ impl<B, E> Route<B, E> {
     {
         Self(BoxCloneService::new(svc))
     }
+
+    pub(crate) fn oneshot_inner(
+        &mut self,
+        req: Request<B>,
+    ) -> Oneshot<BoxCloneService<Request<B>, Response, E>, Request<B>> {
+        self.0.clone().oneshot(req)
+    }
 }
 
 impl<ReqBody, E> Clone for Route<ReqBody, E> {
@@ -64,7 +71,7 @@ where
 
     #[inline]
     fn call(&mut self, req: Request<B>) -> Self::Future {
-        RouteFuture::from_future(self.0.clone().oneshot(req))
+        RouteFuture::from_future(self.oneshot_inner(req))
     }
 }
 
@@ -134,6 +141,9 @@ where
 
     #[inline]
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        #[derive(Clone, Copy)]
+        struct AlreadyPassedThroughRouteFuture;
+
         let this = self.project();
 
         let mut res = match this.kind.project() {
@@ -147,6 +157,16 @@ where
             }
         };
 
+        if res
+            .extensions()
+            .get::<AlreadyPassedThroughRouteFuture>()
+            .is_some()
+        {
+            return Poll::Ready(Ok(res));
+        } else {
+            res.extensions_mut().insert(AlreadyPassedThroughRouteFuture);
+        }
+
         set_allow_header(&mut res, this.allow_header);
 
         // make sure to set content-length before removing the body

axum/src/routing/tests/mod.rs

@@ -645,3 +645,36 @@ async fn head_content_length_through_hyper_server_that_hits_fallback() {
     let res = client.head("/").send().await;
     assert_eq!(res.headers()["content-length"], "3");
 }
+
+#[tokio::test]
+async fn head_with_middleware_applied() {
+    use tower_http::compression::{predicate::SizeAbove, CompressionLayer};
+
+    let app = Router::new()
+        .route("/", get(|| async { "Hello, World!" }))
+        .layer(CompressionLayer::new().compress_when(SizeAbove::new(0)));
+
+    let client = TestClient::new(app);
+
+    // send GET request
+    let res = client
+        .get("/")
+        .header("accept-encoding", "gzip")
+        .send()
+        .await;
+    assert_eq!(res.headers()["transfer-encoding"], "chunked");
+    // cannot have `transfer-encoding: chunked` and `content-length`
+    assert!(!res.headers().contains_key("content-length"));
+
+    // send HEAD request
+    let res = client
+        .head("/")
+        .header("accept-encoding", "gzip")
+        .send()
+        .await;
+    // no response body so no `transfer-encoding`
+    assert!(!res.headers().contains_key("transfer-encoding"));
+    // no content-length since we cannot know it since the response
+    // is compressed
+    assert!(!res.headers().contains_key("content-length"));
+}