feat(api|web): follow through metadata-driven redirects

This is an implementation of the GET handler for the
`x-amz-website-redirect-location`.

This implements the semantics described in
https://docs.aws.amazon.com/AmazonS3/latest/userguide/how-to-page-redirect.html
for the S3 API and the web API.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

Cargo.lock

@@ -197,6 +197,17 @@ dependencies = [
  "zstd-safe",
 ]
 
+[[package]]
+name = "async-recursion"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b43422f69d8ff38f95f1b2bb76517c91589a924d1559a0e935d7c8ce0274c11"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.48",
+]
+
 [[package]]
 name = "async-stream"
 version = "0.3.5"
@@ -1365,6 +1376,7 @@ dependencies = [
  "aes-gcm",
  "argon2",
  "async-compression",
+ "async-recursion",
  "async-trait",
  "base64 0.21.7",
  "bytes",

Cargo.nix

@@ -34,7 +34,7 @@ args@{
   ignoreLockHash,
 }:
 let
-  nixifiedLockHash = "c0aa85d369b22875a652356862a5810c22838970be9fbec558dd108d5232881d";
+  nixifiedLockHash = "fe0e77c1af963cc04accebb4ddd1607df5bbbaa48ca0b7a325f5e4497e21790e";
   workspaceSrc = if args.workspaceSrc == null then ./. else args.workspaceSrc;
   currentLockHash = builtins.hashFile "sha256" (workspaceSrc + /Cargo.lock);
   lockHashIgnored = if ignoreLockHash
@@ -349,6 +349,18 @@ in
     };
   });
   
+  "registry+https://github.com/rust-lang/crates.io-index".async-recursion."1.1.1" = overridableMkRustCrate (profileName: rec {
+    name = "async-recursion";
+    version = "1.1.1";
+    registry = "registry+https://github.com/rust-lang/crates.io-index";
+    src = fetchCratesIo { inherit name version; sha256 = "3b43422f69d8ff38f95f1b2bb76517c91589a924d1559a0e935d7c8ce0274c11"; };
+    dependencies = {
+      proc_macro2 = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".proc-macro2."1.0.78" { inherit profileName; }).out;
+      quote = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".quote."1.0.35" { inherit profileName; }).out;
+      syn = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".syn."2.0.48" { inherit profileName; }).out;
+    };
+  });
+  
   "registry+https://github.com/rust-lang/crates.io-index".async-stream."0.3.5" = overridableMkRustCrate (profileName: rec {
     name = "async-stream";
     version = "0.3.5";
@@ -2003,6 +2015,7 @@ in
       aes_gcm = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".aes-gcm."0.10.3" { inherit profileName; }).out;
       argon2 = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".argon2."0.5.3" { inherit profileName; }).out;
       async_compression = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".async-compression."0.4.6" { inherit profileName; }).out;
+      async_recursion = (buildRustPackages."registry+https://github.com/rust-lang/crates.io-index".async-recursion."1.1.1" { profileName = "__noProfile"; }).out;
       async_trait = (buildRustPackages."registry+https://github.com/rust-lang/crates.io-index".async-trait."0.1.77" { profileName = "__noProfile"; }).out;
       base64 = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".base64."0.21.7" { inherit profileName; }).out;
       bytes = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".bytes."1.5.0" { inherit profileName; }).out;

src/api/Cargo.toml

@@ -68,6 +68,7 @@ quick-xml.workspace = true
 opentelemetry.workspace = true
 opentelemetry-prometheus = { workspace = true, optional = true }
 prometheus = { workspace = true, optional = true }
+async-recursion = "1.1.1"
 
 [features]
 k2v = [ "garage_util/k2v", "garage_model/k2v" ]

src/api/s3/api_server.rs

@@ -201,7 +201,10 @@ impl ApiHandler for S3ApiServer {
 					response_content_type,
 					response_expires,
 				};
-				handle_get(ctx, &req, &key, part_number, overrides).await
+				// Redirects are flattened over the S3 API as per:
+				// https://docs.aws.amazon.com/AmazonS3/latest/userguide/how-to-page-redirect.html
+				// > REST endpoint – Amazon S3 doesn't redirect the page request. It returns the requested object.
+				handle_get(ctx, &req, &key, part_number, overrides, true).await
 			}
 			Endpoint::UploadPart {
 				key,

src/api/s3/get.rs

@@ -280,22 +280,25 @@ pub async fn handle_head_without_ctx(
 /// Handle GET request
 pub async fn handle_get(
 	ctx: ReqCtx,
-	req: &Request<impl Body>,
+	req: &Request<impl Body + std::marker::Sync>,
 	key: &str,
 	part_number: Option<u64>,
 	overrides: GetObjectOverrides,
+	flatten_redirect: bool
 ) -> Result<Response<ResBody>, Error> {
-	handle_get_without_ctx(ctx.garage, req, ctx.bucket_id, key, part_number, overrides).await
+	handle_get_without_ctx(ctx.garage, req, ctx.bucket_id, key, part_number, overrides, flatten_redirect).await
 }
 
 /// Handle GET request
+#[async_recursion::async_recursion]
 pub async fn handle_get_without_ctx(
 	garage: Arc<Garage>,
-	req: &Request<impl Body>,
+	req: &Request<impl Body + std::marker::Sync>,
 	bucket_id: Uuid,
 	key: &str,
 	part_number: Option<u64>,
 	overrides: GetObjectOverrides,
+	flatten_redirect: bool
 ) -> Result<Response<ResBody>, Error> {
 	let object = garage
 		.object_table
@@ -329,6 +332,30 @@ pub async fn handle_get_without_ctx(
 
 	let checksum_mode = checksum_mode(&req);
 
+	if let Some(redirect_hdr) = headers
+		.headers
+		.iter()
+		.find(|(k, _)| k == "x-amz-website-redirect-location")
+		.map(|(_, v)| v)
+	{
+		if flatten_redirect {
+			return handle_get_without_ctx(garage,
+				req,
+				bucket_id,
+				redirect_hdr,
+				part_number,
+				overrides,
+				flatten_redirect
+			).await;
+		} else {
+			return Ok(Response::builder()
+					.status(StatusCode::FOUND)
+					.header("Location", redirect_hdr)
+					.body(empty_body())
+					.unwrap());
+		}
+	}
+
 	match (part_number, parse_range_header(req, last_v_meta.size)?) {
 		(Some(_), Some(_)) => Err(Error::bad_request(
 			"Cannot specify both partNumber and Range header",

src/garage/tests/s3/website.rs

@@ -181,6 +181,16 @@ async fn test_website_s3_api() {
 		.await
 		.unwrap();
 
+	ctx.client
+		.put_object()
+		.bucket(&bucket)
+		.key("site/home-redirected.html")
+		.website_redirect_location("/site/home.html")
+		.body(ByteStream::from_static(&[]))
+		.send()
+		.await
+		.unwrap();
+
 	let conf = WebsiteConfiguration::builder()
 		.index_document(
 			IndexDocument::builder()
@@ -274,6 +284,29 @@ async fn test_website_s3_api() {
 		);
 	}
 
+	// Test redirection with CORS
+	{
+		let req = Request::builder()
+			.method("GET")
+			.uri(format!("http://127.0.0.1:{}/site/home-redirected.html", ctx.garage.web_port))
+			.header("Host", format!("{}.web.garage", BCKT_NAME))
+			.header("Origin", "https://example.com")
+			.body(Body::new(Bytes::new()))
+			.unwrap();
+
+		let resp = client.request(req).await.unwrap();
+
+		assert!(resp.status().is_redirection());
+		assert_eq!(
+			resp.headers().get("access-control-allow-origin").unwrap(),
+			"*"
+		);
+		assert_eq!(
+			resp.headers().get(http::header::LOCATION).unwrap(),
+			"/site/home.html"
+		);
+	}
+
 	// Test ErrorDocument on 404
 	{
 		let req = Request::builder()

src/web/web_server.rs

@@ -249,6 +249,9 @@ impl WebServer {
 				handle_head_without_ctx(self.garage.clone(), req, bucket_id, &key, None).await
 			}
 			Method::GET => {
+				// Redirects are not flattened in the web API, as per:
+				// https://docs.aws.amazon.com/AmazonS3/latest/userguide/how-to-page-redirect.html
+				// > Region-specific website endpoint – Amazon S3 redirects the page request according to the value of the x-amz-website-redirect-location property.
 				handle_get_without_ctx(
 					self.garage.clone(),
 					req,
@@ -256,6 +259,7 @@ impl WebServer {
 					&key,
 					None,
 					Default::default(),
+					false
 				)
 				.await
 			}
@@ -309,6 +313,7 @@ impl WebServer {
 					&error_document,
 					None,
 					Default::default(),
+					false
 				)
 				.await
 				{