diag: log checkOrigin rejections

src/auth.js

@@ -80,12 +80,20 @@ export function checkOrigin(req, res, next) {
   if (['GET', 'HEAD', 'OPTIONS'].includes(req.method)) return next();
   const origin = req.get('origin') || req.get('referer');
   if (origin) {
+    const allowed = allowedHosts(req);
     try {
       const host = new URL(origin).host;
-      if (allowedHosts(req).has(host)) return next();
+      if (allowed.has(host)) return next();
     } catch {
       /* fall through */
     }
+    log.warn('checkOrigin rejected', {
+      origin,
+      host: req.get('host'),
+      xForwardedHost: req.get('x-forwarded-host'),
+      allowed: [...allowed],
+      path: req.path,
+    });
     return res.status(403).send('Bad origin');
   }
   // No Origin/Referer header (e.g. some curl uploads) — allow; SameSite cookie still guards browsers.