move redirect to util to keep express-routes isolated

src/router.ts

@@ -7,6 +7,7 @@ import validate from "./services/validate";
 import {postBody} from "./models/post";
 import {EmailService} from "./services/email";
 import {CaptchaService} from "./services/captcha";
+import getRedirectUrl from "./util/redirect";
 
 const router: Router = Router();
 
@@ -111,17 +112,6 @@ router.post("/:target", async (req: Request, res: Response) => {
     });
 });
 
-function getRedirectUrl(req: Request, targetRedirectUrl: string) {
-    let redirectUrl = targetRedirectUrl
-
-    const urlPattern = /^(https?):\/\//;
-    if(!urlPattern.test(redirectUrl)) {
-        redirectUrl = (req.header('Referer') || '/') + redirectUrl;
-    }
-
-    return redirectUrl
-}
-
 router.all("*", (req: Request, res: Response) => res.status(404).end());
 
 export default router;

src/util/redirect.ts

@@ -0,0 +1,20 @@
+import {Request} from "express";
+
+/**
+ * Create absolute Url from relative redirectUrl
+ * @param req incoming Request
+ * @param targetRedirectUrl redirectUrl from target
+ * @returns String
+ */
+function getRedirectUrl(req: Request, targetRedirectUrl: string) {
+    let redirectUrl = targetRedirectUrl
+
+    const urlPattern = /^(https?):\/\//;
+    if(!urlPattern.test(redirectUrl)) {
+        redirectUrl = (req.header('Referer') || '/') + redirectUrl;
+    }
+
+    return redirectUrl
+}
+
+export default getRedirectUrl;