Add ServeDir::fallback

tower-http/CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Added
 
+- Add `ServeDir::{fallback, not_found_service}` for calling another service if
+  the file cannot be found.
 - Add `SetStatus` to override status codes.
 - **cors**: Added `CorsLayer::very_permissive` which is like
   `CorsLayer::permissive` except it (truly) allows credentials. This is made

tower-http/Cargo.toml

@@ -79,7 +79,7 @@ auth = ["base64"]
 catch-panic = ["tracing", "futures-util/std"]
 cors = []
 follow-redirect = ["iri-string", "tower/util"]
-fs = ["tokio/fs", "tokio-util/io", "tokio/io-util", "mime_guess", "mime", "percent-encoding", "httpdate"]
+fs = ["tokio/fs", "tokio-util/io", "tokio/io-util", "mime_guess", "mime", "percent-encoding", "httpdate", "set-status"]
 map-request-body = []
 map-response-body = []
 metrics = ["tokio/time"]

tower-http/src/services/fs/mod.rs

@@ -2,8 +2,8 @@
 
 use bytes::Bytes;
 use futures_util::Stream;
-use http::{HeaderMap, Response, StatusCode};
-use http_body::{combinators::BoxBody, Body, Empty};
+use http::{HeaderMap, StatusCode};
+use http_body::Body;
 use httpdate::HttpDate;
 use pin_project_lite::pin_project;
 use std::fs::Metadata;
@@ -28,6 +28,7 @@ use crate::content_encoding::{Encoding, QValue, SupportedEncodings};
 
 pub use self::{
     serve_dir::{
+        DefaultServeDirFallback,
         // The response body and future are used for both ServeDir and ServeFile
         ResponseBody as ServeFileSystemResponseBody,
         ResponseFuture as ServeFileSystemResponseFuture,
@@ -189,22 +190,6 @@ where
     }
 }
 
-fn response_from_io_error(
-    err: io::Error,
-) -> Result<Response<BoxBody<Bytes, io::Error>>, io::Error> {
-    match err.kind() {
-        io::ErrorKind::NotFound | io::ErrorKind::PermissionDenied => {
-            let res = Response::builder()
-                .status(StatusCode::NOT_FOUND)
-                .body(Empty::new().map_err(|err| match err {}).boxed())
-                .unwrap();
-
-            Ok(res)
-        }
-        _ => Err(err),
-    }
-}
-
 struct LastModified(HttpDate);
 
 impl From<SystemTime> for LastModified {