From 0693a4195b866d1e0db089331acf6beb99a4dcf5 Mon Sep 17 00:00:00 2001
From: Ephraim Duncan <55143799+ephraimduncan@users.noreply.github.com>
Date: Wed, 16 Sep 2026 04:10:55 +0000
Subject: [PATCH] refactor(openpage): simplify the cors policy (#3338)

---
 apps/openpage-api/lib/cors.ts | 137 +++-------------------------------
 1 file changed, 9 insertions(+), 128 deletions(-)

diff --git a/apps/openpage-api/lib/cors.ts b/apps/openpage-api/lib/cors.ts
index 78dcebde5..707a258b3 100644
--- a/apps/openpage-api/lib/cors.ts
+++ b/apps/openpage-api/lib/cors.ts
@@ -1,142 +1,23 @@
 /**
- * Multi purpose CORS lib.
- * Note: Based on the `cors` package in npm but using only web APIs.
- * Taken from: https://github.com/vercel/examples/blob/main/edge-functions/cors/lib/cors.ts
+ * Apply the public statistics API's wildcard CORS policy, without credentials.
  */
-
-type StaticOrigin = boolean | string | RegExp | (boolean | string | RegExp)[];
-
-type OriginFn = (origin: string | undefined, req: Request) => StaticOrigin | Promise<StaticOrigin>;
-
-interface CorsOptions {
-  origin?: StaticOrigin | OriginFn;
-  methods?: string | string[];
-  allowedHeaders?: string | string[];
-  exposedHeaders?: string | string[];
-  credentials?: boolean;
-  maxAge?: number;
-  preflightContinue?: boolean;
-  optionsSuccessStatus?: number;
-}
-
-const defaultOptions: CorsOptions = {
-  origin: '*',
-  methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
-  preflightContinue: false,
-  optionsSuccessStatus: 204,
-};
-
-function isOriginAllowed(origin: string, allowed: StaticOrigin): boolean {
-  return Array.isArray(allowed)
-    ? allowed.some((o) => isOriginAllowed(origin, o))
-    : typeof allowed === 'string'
-      ? origin === allowed
-      : allowed instanceof RegExp
-        ? allowed.test(origin)
-        : !!allowed;
-}
-
-function getOriginHeaders(reqOrigin: string | undefined, origin: StaticOrigin) {
-  const headers = new Headers();
-
-  if (origin === '*') {
-    headers.set('Access-Control-Allow-Origin', '*');
-  } else if (typeof origin === 'string') {
-    headers.set('Access-Control-Allow-Origin', origin);
-    headers.append('Vary', 'Origin');
-  } else {
-    const allowed = isOriginAllowed(reqOrigin ?? '', origin);
-
-    if (allowed && reqOrigin) {
-      headers.set('Access-Control-Allow-Origin', reqOrigin);
-    }
-    headers.append('Vary', 'Origin');
-  }
-
-  return headers;
-}
-
-async function originHeadersFromReq(req: Request, origin: StaticOrigin | OriginFn) {
-  const reqOrigin = req.headers.get('Origin') || undefined;
-  const value = typeof origin === 'function' ? await origin(reqOrigin, req) : origin;
-
-  if (!value) {
-    return;
-  }
-  return getOriginHeaders(reqOrigin, value);
-}
-
-function getAllowedHeaders(req: Request, allowed?: string | string[]) {
-  const headers = new Headers();
-
-  if (!allowed) {
-    allowed = req.headers.get('Access-Control-Request-Headers')!;
-    headers.append('Vary', 'Access-Control-Request-Headers');
-  } else if (Array.isArray(allowed)) {
-    allowed = allowed.join(',');
-  }
-  if (allowed) {
-    headers.set('Access-Control-Allow-Headers', allowed);
-  }
-
-  return headers;
-}
-
-export default async function cors(req: Request, res: Response, options?: CorsOptions) {
-  const opts = { ...defaultOptions, ...options };
+export default async function cors(req: Request, res: Response): Promise<Response> {
   const { headers } = res;
-  const originHeaders = await originHeadersFromReq(req, opts.origin ?? false);
-  const mergeHeaders = (v: string, k: string) => {
-    if (k === 'Vary') {
-      headers.append(k, v);
-    } else {
-      headers.set(k, v);
-    }
-  };
+  headers.set('Access-Control-Allow-Origin', '*');
 
-  // If there's no origin we won't touch the response
-  if (!originHeaders) {
-    return res;
-  }
-
-  originHeaders.forEach(mergeHeaders);
-
-  if (opts.credentials) {
-    headers.set('Access-Control-Allow-Credentials', 'true');
-  }
-
-  const exposed = Array.isArray(opts.exposedHeaders) ? opts.exposedHeaders.join(',') : opts.exposedHeaders;
-
-  if (exposed) {
-    headers.set('Access-Control-Expose-Headers', exposed);
-  }
-
-  // Handle the preflight request
   if (req.method === 'OPTIONS') {
-    if (opts.methods) {
-      const methods = Array.isArray(opts.methods) ? opts.methods.join(',') : opts.methods;
+    headers.set('Access-Control-Allow-Methods', 'GET,HEAD,PUT,PATCH,POST,DELETE');
+    headers.set('Vary', 'Access-Control-Request-Headers');
 
-      headers.set('Access-Control-Allow-Methods', methods);
-    }
+    const allowedHeaders = req.headers.get('Access-Control-Request-Headers');
 
-    getAllowedHeaders(req, opts.allowedHeaders).forEach(mergeHeaders);
-
-    if (typeof opts.maxAge === 'number') {
-      headers.set('Access-Control-Max-Age', String(opts.maxAge));
-    }
-
-    if (opts.preflightContinue) {
-      return res;
+    if (allowedHeaders) {
+      headers.set('Access-Control-Allow-Headers', allowedHeaders);
     }
 
     headers.set('Content-Length', '0');
-    return new Response(null, { status: opts.optionsSuccessStatus, headers });
+    return new Response(null, { status: 204, headers });
   }
 
-  // If we got here, it's a normal request
   return res;
 }
-
-export function initCors(options?: CorsOptions) {
-  return async (req: Request, res: Response) => cors(req, res, options);
-}