Add 'Options::NormalizeDirs' to 'StaticFiles'.

Closes #1198.

Co-authored-by: Keith Wansbrough <keithw@lochan.org>

contrib/lib/src/serve.rs

@@ -17,9 +17,9 @@
 use std::path::{PathBuf, Path};
 
 use rocket::{Request, Data, Route};
-use rocket::http::{Method, uri::Segments};
+use rocket::http::{Method, uri::Segments, ext::IntoOwned};
 use rocket::handler::{Handler, Outcome};
-use rocket::response::NamedFile;
+use rocket::response::{NamedFile, Redirect};
 
 /// A bitset representing configurable options for the [`StaticFiles`] handler.
 ///
@@ -38,7 +38,8 @@ pub struct Options(u8);
 #[allow(non_upper_case_globals, non_snake_case)]
 impl Options {
     /// `Options` representing the empty set. No dotfiles or index pages are
-    /// rendered. This is different than the _default_, which enables `Index`.
+    /// rendered. This is different than the [`Options::default()`], which
+    /// enables `Index`.
     pub const None: Options = Options(0b0000);
 
     /// `Options` enabling responding to requests for a directory with the
@@ -53,6 +54,16 @@ impl Options {
     /// directories beginning with `.`. This is _not_ enabled by default.
     pub const DotFiles: Options = Options(0b0010);
 
+    /// `Options` that normalizes directory requests by redirecting requests to
+    /// directory paths without a trailing slash to ones with a trailing slash.
+    ///
+    /// When enabled, the [`StaticFiles`] handler will respond to requests for a
+    /// directory without a trailing `/` with a permanent redirect (308) to the
+    /// same path with a trailing `/`. This ensures relative URLs within any
+    /// document served for that directory will be interpreted relative to that
+    /// directory, rather than its parent. This is _not_ enabled by default.
+    pub const NormalizeDirs: Options = Options(0b0100);
+
     /// Returns `true` if `self` is a superset of `other`. In other words,
     /// returns `true` if all of the options in `other` are also in `self`.
     ///
@@ -79,6 +90,7 @@ impl Options {
     }
 }
 
+/// The default set of options: `Options::Index`.
 impl Default for Options {
     fn default() -> Self {
         Options::Index
@@ -263,7 +275,10 @@ impl StaticFiles {
 impl Into<Vec<Route>> for StaticFiles {
     fn into(self) -> Vec<Route> {
         let non_index = Route::ranked(self.rank, Method::Get, "/<path..>", self.clone());
-        if self.options.contains(Options::Index) {
+        // `Index` requires routing the index for obvious reasons.
+        // `NormalizeDirs` requires routing the index so a `.mount("/foo")` with
+        // a request `/foo`, can be redirected to `/foo/`.
+        if self.options.contains(Options::Index) || self.options.contains(Options::NormalizeDirs) {
             let index = Route::ranked(self.rank, Method::Get, "/", self);
             vec![index, non_index]
         } else {
@@ -275,6 +290,14 @@ impl Into<Vec<Route>> for StaticFiles {
 impl Handler for StaticFiles {
     fn handle<'r>(&self, req: &'r Request<'_>, data: Data) -> Outcome<'r> {
         fn handle_dir<'r>(opt: Options, r: &'r Request<'_>, d: Data, path: &Path) -> Outcome<'r> {
+            if opt.contains(Options::NormalizeDirs) && !r.uri().path().ends_with('/') {
+                let new_path = r.uri().map_path(|p| p.to_owned() + "/")
+                    .expect("adding a trailing slash to a known good path results in a valid path")
+                    .into_owned();
+
+                return Outcome::from_or_forward(r, d, Redirect::permanent(new_path));
+            }
+
             if !opt.contains(Options::Index) {
                 return Outcome::forward(d);
             }

contrib/lib/tests/static_files.rs

@@ -24,6 +24,8 @@ mod static_tests {
             .mount("/dots", StaticFiles::new(&root, Options::DotFiles))
             .mount("/index", StaticFiles::new(&root, Options::Index))
             .mount("/both", StaticFiles::new(&root, Options::DotFiles | Options::Index))
+            .mount("/redir", StaticFiles::new(&root, Options::NormalizeDirs))
+            .mount("/redir_index", StaticFiles::new(&root, Options::NormalizeDirs | Options::Index))
     }
 
     static REGULAR_FILES: &[&str] = &[
@@ -143,4 +145,50 @@ mod static_tests {
         assert_all(&client, "both", HIDDEN_FILES, true);
         assert_all(&client, "both", INDEXED_DIRECTORIES, true);
     }
+
+    #[test]
+    fn test_redirection() {
+        let client = Client::new(rocket()).expect("valid rocket");
+
+        // Redirection only happens if enabled, and doesn't affect index behaviour.
+        let response = client.get("/no_index/inner").dispatch();
+        assert_eq!(response.status(), Status::NotFound);
+
+        let response = client.get("/index/inner").dispatch();
+        assert_eq!(response.status(), Status::Ok);
+
+        let response = client.get("/redir/inner").dispatch();
+        assert_eq!(response.status(), Status::PermanentRedirect);
+        assert_eq!(response.headers().get("Location").next(), Some("/redir/inner/"));
+
+        let response = client.get("/redir/inner?foo=bar").dispatch();
+        assert_eq!(response.status(), Status::PermanentRedirect);
+        assert_eq!(response.headers().get("Location").next(), Some("/redir/inner/?foo=bar"));
+
+        let response = client.get("/redir_index/inner").dispatch();
+        assert_eq!(response.status(), Status::PermanentRedirect);
+        assert_eq!(response.headers().get("Location").next(), Some("/redir_index/inner/"));
+
+        // Paths with trailing slash are unaffected.
+        let response = client.get("/redir/inner/").dispatch();
+        assert_eq!(response.status(), Status::NotFound);
+
+        let response = client.get("/redir_index/inner/").dispatch();
+        assert_eq!(response.status(), Status::Ok);
+
+        // Root of route is also redirected.
+        let response = client.get("/no_index").dispatch();
+        assert_eq!(response.status(), Status::NotFound);
+
+        let response = client.get("/index").dispatch();
+        assert_eq!(response.status(), Status::Ok);
+
+        let response = client.get("/redir").dispatch();
+        assert_eq!(response.status(), Status::PermanentRedirect);
+        assert_eq!(response.headers().get("Location").next(), Some("/redir/"));
+
+        let response = client.get("/redir_index").dispatch();
+        assert_eq!(response.status(), Status::PermanentRedirect);
+        assert_eq!(response.headers().get("Location").next(), Some("/redir_index/"));
+    }
 }