From 49100f2fe98a807c4acda500a00fb033f18d5c9a Mon Sep 17 00:00:00 2001
From: Kamil Kisiela <kamil.kisiela@gmail.com>
Date: Thu, 29 Aug 2024 16:39:50 +0200
Subject: [PATCH] Add CORS headers to CDN Worker (#5559)

---
 packages/services/cdn-worker/src/index.ts | 41 ++++++++++++++---------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/packages/services/cdn-worker/src/index.ts b/packages/services/cdn-worker/src/index.ts
index ac0a2b172..39f0abe2a 100644
--- a/packages/services/cdn-worker/src/index.ts
+++ b/packages/services/cdn-worker/src/index.ts
@@ -192,8 +192,13 @@ const handler: ExportedHandler<Env> = {
       },
     });
 
+    const { corsify, preflight } = itty.createCors();
+
     const router = itty
       .Router()
+      // Handles all OPTIONS and preflight requests.
+      // https://github.com/kwhitley/itty.dev/blob/v4.x/src/routes/itty-router/cors/%2Bpage.md#preflight-middleware
+      .all('*', preflight)
       .get(
         '/_health',
         () =>
@@ -205,23 +210,29 @@ const handler: ExportedHandler<Env> = {
       // Legacy CDN Handlers
       .get('*', handleRequest);
 
-    try {
-      return await router.handle(request, sentry.captureException.bind(sentry)).then(response => {
-        if (response) {
-          return response;
-        }
+    return (
+      router
+        .handle(request, sentry.captureException.bind(sentry))
+        .then(response => {
+          if (response) {
+            return response;
+          }
 
-        sentry.addBreadcrumb({
-          message: 'No response from router',
-        });
+          sentry.addBreadcrumb({
+            message: 'No response from router',
+          });
 
-        return createResponse(analytics, 'Not found', { status: 404 }, 'unknown', request);
-      });
-    } catch (error) {
-      console.error(error);
-      sentry.captureException(error);
-      return new UnexpectedError(analytics, request);
-    }
+          return createResponse(analytics, 'Not found', { status: 404 }, 'unknown', request);
+        })
+        .catch(error => {
+          console.error(error);
+          sentry.captureException(error);
+          return new UnexpectedError(analytics, request);
+        })
+        // Adds the appropriate CORS headers to any Response.
+        // https://github.com/kwhitley/itty.dev/blob/v4.x/src/routes/itty-router/cors/%2Bpage.md#corsify
+        .then(corsify)
+    );
   },
 };