From c5754810c0b2cda1442e9a7593a707ba431b0179 Mon Sep 17 00:00:00 2001
From: Claas Augner <caugner@mozilla.com>
Date: Fri, 12 May 2023 12:50:13 +0200
Subject: [PATCH] fix(cloud-function): normalize encoded leading slash

---
 cloud-function/src/middlewares/redirect-leading-slash.ts | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/cloud-function/src/middlewares/redirect-leading-slash.ts b/cloud-function/src/middlewares/redirect-leading-slash.ts
index acd50cae75fa..910c0ba8377b 100644
--- a/cloud-function/src/middlewares/redirect-leading-slash.ts
+++ b/cloud-function/src/middlewares/redirect-leading-slash.ts
@@ -20,9 +20,14 @@ export async function redirectLeadingSlash(
   next: NextFunction
 ) {
   const pathname = req.url;
-  if (pathname.startsWith("//")) {
-    return redirect(res, pathname.replace(/^\/+/g, "/"));
+  const normalizedPathname = normalizeLeadingSlash(pathname);
+  if (pathname !== normalizedPathname) {
+    return redirect(res, normalizedPathname);
   }
 
   next();
 }
+
+function normalizeLeadingSlash(pathname: string): string {
+  return pathname.replace(/^(\/|%2f)+/i, "/");
+}