normalize_path: Add Append mode

tower-http/src/builder.rs

@@ -366,6 +366,16 @@ pub trait ServiceBuilderExt<L>: sealed::Sealed<L> + Sized {
     fn trim_trailing_slash(
         self,
     ) -> ServiceBuilder<Stack<crate::normalize_path::NormalizePathLayer, L>>;
+
+    /// Append trailing slash to paths.
+    ///
+    /// See [`tower_http::normalize_path`] for more details.
+    ///
+    /// [`tower_http::normalize_path`]: crate::normalize_path
+    #[cfg(feature = "normalize-path")]
+    fn append_trailing_slash(
+        self,
+    ) -> ServiceBuilder<Stack<crate::normalize_path::NormalizePathLayer, L>>;
 }
 
 impl<L> sealed::Sealed<L> for ServiceBuilder<L> {}
@@ -596,4 +606,11 @@ impl<L> ServiceBuilderExt<L> for ServiceBuilder<L> {
     ) -> ServiceBuilder<Stack<crate::normalize_path::NormalizePathLayer, L>> {
         self.layer(crate::normalize_path::NormalizePathLayer::trim_trailing_slash())
     }
+
+    #[cfg(feature = "normalize-path")]
+    fn append_trailing_slash(
+        self,
+    ) -> ServiceBuilder<Stack<crate::normalize_path::NormalizePathLayer, L>> {
+        self.layer(crate::normalize_path::NormalizePathLayer::append_trailing_slash())
+    }
 }

tower-http/src/normalize_path.rs

@@ -1,8 +1,5 @@
 //! Middleware that normalizes paths.
 //!
-//! Any trailing slashes from request paths will be removed. For example, a request with `/foo/`
-//! will be changed to `/foo` before reaching the inner service.
-//!
 //! # Example
 //!
 //! ```
@@ -45,27 +42,53 @@ use std::{
 use tower_layer::Layer;
 use tower_service::Service;
 
+/// Different modes of normalizing paths
+#[derive(Debug, Copy, Clone)]
+enum NormalizeMode {
+    /// Normalizes paths by trimming the trailing slashes, e.g. /foo/ -> /foo
+    Trim,
+    /// Normalizes paths by appending trailing slash, e.g. /foo -> /foo/
+    Append,
+}
+
 /// Layer that applies [`NormalizePath`] which normalizes paths.
 ///
 /// See the [module docs](self) for more details.
 #[derive(Debug, Copy, Clone)]
-pub struct NormalizePathLayer {}
+pub struct NormalizePathLayer {
+    mode: NormalizeMode,
+}
 
 impl NormalizePathLayer {
     /// Create a new [`NormalizePathLayer`].
     ///
     /// Any trailing slashes from request paths will be removed. For example, a request with `/foo/`
     /// will be changed to `/foo` before reaching the inner service.
     pub fn trim_trailing_slash() -> Self {
-        NormalizePathLayer {}
+        NormalizePathLayer {
+            mode: NormalizeMode::Trim,
+        }
+    }
+
+    /// Create a new [`NormalizePathLayer`].
+    ///
+    /// Request paths without trailing slash will be appended with a trailing slash. For example, a request with `/foo`
+    /// will be changed to `/foo/` before reaching the inner service.
+    pub fn append_trailing_slash() -> Self {
+        NormalizePathLayer {
+            mode: NormalizeMode::Append,
+        }
     }
 }
 
 impl<S> Layer<S> for NormalizePathLayer {
     type Service = NormalizePath<S>;
 
     fn layer(&self, inner: S) -> Self::Service {
-        NormalizePath::trim_trailing_slash(inner)
+        NormalizePath {
+            mode: self.mode,
+            inner,
+        }
     }
 }
 
@@ -74,16 +97,25 @@ impl<S> Layer<S> for NormalizePathLayer {
 /// See the [module docs](self) for more details.
 #[derive(Debug, Copy, Clone)]
 pub struct NormalizePath<S> {
+    mode: NormalizeMode,
     inner: S,
 }
 
 impl<S> NormalizePath<S> {
-    /// Create a new [`NormalizePath`].
-    ///
-    /// Any trailing slashes from request paths will be removed. For example, a request with `/foo/`
-    /// will be changed to `/foo` before reaching the inner service.
+    /// Construct a new [`NormalizePath`] with trim mode.
     pub fn trim_trailing_slash(inner: S) -> Self {
-        Self { inner }
+        Self {
+            mode: NormalizeMode::Trim,
+            inner,
+        }
+    }
+
+    /// Construct a new [`NormalizePath`] with append mode.
+    pub fn append_trailing_slash(inner: S) -> Self {
+        Self {
+            mode: NormalizeMode::Append,
+            inner,
+        }
     }
 
     define_inner_service_accessors!();
@@ -103,12 +135,15 @@ where
     }
 
     fn call(&mut self, mut req: Request<ReqBody>) -> Self::Future {
-        normalize_trailing_slash(req.uri_mut());
+        match self.mode {
+            NormalizeMode::Trim => trim_trailing_slash(req.uri_mut()),
+            NormalizeMode::Append => append_trailing_slash(req.uri_mut()),
+        }
         self.inner.call(req)
     }
 }
 
-fn normalize_trailing_slash(uri: &mut Uri) {
+fn trim_trailing_slash(uri: &mut Uri) {
     if !uri.path().ends_with('/') && !uri.path().starts_with("//") {
         return;
     }
@@ -137,14 +172,48 @@ fn normalize_trailing_slash(uri: &mut Uri) {
     }
 }
 
+fn append_trailing_slash(uri: &mut Uri) {
+    if uri.path().ends_with("/") && !uri.path().ends_with("//") {
+        return;
+    }
+
+    let trimmed = uri.path().trim_matches('/');
+    let new_path = if trimmed.is_empty() {
+        "/".to_string()
+    } else {
+        format!("/{trimmed}/")
+    };
+
+    let mut parts = uri.clone().into_parts();
+
+    let new_path_and_query = if let Some(path_and_query) = &parts.path_and_query {
+        let new_path_and_query = if let Some(query) = path_and_query.query() {
+            Cow::Owned(format!("{new_path}?{query}"))
+        } else {
+            new_path.into()
+        }
+        .parse()
+        .unwrap();
+
+        Some(new_path_and_query)
+    } else {
+        Some(new_path.parse().unwrap())
+    };
+
+    parts.path_and_query = new_path_and_query;
+    if let Ok(new_uri) = Uri::from_parts(parts) {
+        *uri = new_uri;
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use std::convert::Infallible;
     use tower::{ServiceBuilder, ServiceExt};
 
     #[tokio::test]
-    async fn works() {
+    async fn trim_works() {
         async fn handle(request: Request<()>) -> Result<Response<String>, Infallible> {
             Ok(Response::new(request.uri().to_string()))
         }
@@ -168,63 +237,148 @@ mod tests {
     #[test]
     fn is_noop_if_no_trailing_slash() {
         let mut uri = "/foo".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo");
     }
 
     #[test]
     fn maintains_query() {
         let mut uri = "/foo/?a=a".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo?a=a");
     }
 
     #[test]
     fn removes_multiple_trailing_slashes() {
         let mut uri = "/foo////".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo");
     }
 
     #[test]
     fn removes_multiple_trailing_slashes_even_with_query() {
         let mut uri = "/foo////?a=a".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo?a=a");
     }
 
     #[test]
     fn is_noop_on_index() {
         let mut uri = "/".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/");
     }
 
     #[test]
     fn removes_multiple_trailing_slashes_on_index() {
         let mut uri = "////".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/");
     }
 
     #[test]
     fn removes_multiple_trailing_slashes_on_index_even_with_query() {
         let mut uri = "////?a=a".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/?a=a");
     }
 
     #[test]
     fn removes_multiple_preceding_slashes_even_with_query() {
         let mut uri = "///foo//?a=a".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo?a=a");
     }
 
     #[test]
     fn removes_multiple_preceding_slashes() {
         let mut uri = "///foo".parse::<Uri>().unwrap();
-        normalize_trailing_slash(&mut uri);
+        trim_trailing_slash(&mut uri);
         assert_eq!(uri, "/foo");
     }
+
+    #[tokio::test]
+    async fn append_works() {
+        async fn handle(request: Request<()>) -> Result<Response<String>, Infallible> {
+            Ok(Response::new(request.uri().to_string()))
+        }
+
+        let mut svc = ServiceBuilder::new()
+            .layer(NormalizePathLayer::append_trailing_slash())
+            .service_fn(handle);
+
+        let body = svc
+            .ready()
+            .await
+            .unwrap()
+            .call(Request::builder().uri("/foo").body(()).unwrap())
+            .await
+            .unwrap()
+            .into_body();
+
+        assert_eq!(body, "/foo/");
+    }
+
+    #[test]
+    fn is_noop_if_trailing_slash() {
+        let mut uri = "/foo/".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/");
+    }
+
+    #[test]
+    fn append_maintains_query() {
+        let mut uri = "/foo?a=a".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/?a=a");
+    }
+
+    #[test]
+    fn append_only_keeps_one_slash() {
+        let mut uri = "/foo////".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/");
+    }
+
+    #[test]
+    fn append_only_keeps_one_slash_even_with_query() {
+        let mut uri = "/foo////?a=a".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/?a=a");
+    }
+
+    #[test]
+    fn append_is_noop_on_index() {
+        let mut uri = "/".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/");
+    }
+
+    #[test]
+    fn append_removes_multiple_trailing_slashes_on_index() {
+        let mut uri = "////".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/");
+    }
+
+    #[test]
+    fn append_removes_multiple_trailing_slashes_on_index_even_with_query() {
+        let mut uri = "////?a=a".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/?a=a");
+    }
+
+    #[test]
+    fn append_removes_multiple_preceding_slashes_even_with_query() {
+        let mut uri = "///foo//?a=a".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/?a=a");
+    }
+
+    #[test]
+    fn append_removes_multiple_preceding_slashes() {
+        let mut uri = "///foo".parse::<Uri>().unwrap();
+        append_trailing_slash(&mut uri);
+        assert_eq!(uri, "/foo/");
+    }
 }

tower-http/src/service_ext.rs

@@ -413,6 +413,19 @@ pub trait ServiceExt {
     {
         crate::normalize_path::NormalizePath::trim_trailing_slash(self)
     }
+
+    /// Append trailing slash to paths.
+    ///
+    /// See [`tower_http::normalize_path`] for more details.
+    ///
+    /// [`tower_http::normalize_path`]: crate::normalize_path
+    #[cfg(feature = "normalize-path")]
+    fn append_trailing_slash(self) -> crate::normalize_path::NormalizePath<Self>
+    where
+        Self: Sized,
+    {
+        crate::normalize_path::NormalizePath::append_trailing_slash(self)
+    }
 }
 
 impl<T> ServiceExt for T {}