feat: handle initial redirect through redirect server request handler (#138)

Author: gribnoysup

src/api.ts

@@ -261,6 +261,10 @@ export type RedirectServerRequestInfo = {
   /** The suggested HTTP status code. For unknown-url, this is 404. */
   status: number;
 } & (
+  | {
+      result: 'redirecting';
+      location: string;
+    }
   | {
       result: 'rejected';
       /** Error information reported by the IdP as defined in RFC6749 section 4.1.2.1 */

src/rfc-8252-http-server.spec.ts

@@ -411,6 +411,16 @@ describe('RFC8252HTTPServer', function () {
       url = new URL(server.listeningRedirectUrl || '');
     });
 
+    it('handles redirecting case', async function () {
+      const { localUrl } = await server.addRedirect('http://example.com');
+      const res = await fetch(localUrl, { follow: 0 });
+      expect(res.status).to.eq(307);
+      expect(await res.json()).to.have.property(
+        'location',
+        'http://example.com'
+      );
+    });
+
     it('handles the success case', async function () {
       const params = new URLSearchParams([
         ['foo', 'bar'],

src/rfc-8252-http-server.ts

@@ -123,9 +123,13 @@ export class RFC8252HTTPServer {
     // This can be helpful for figuring out whether a browser was
     // opened successfully.
     entry.onAccessed();
-    res.status(307);
-    res.set('Location', entry.targetUrl);
-    res.send();
+    this.redirectServerHandler({
+      req,
+      res,
+      status: 307,
+      result: 'redirecting',
+      location: entry.targetUrl,
+    });
   };
 
   private _handleOIDCCallback: RequestHandler = (req, res) => {
@@ -515,6 +519,10 @@ function defaultRedirectServerHandler(info: RedirectServerRequestInfo): void {
   res.statusCode = status;
   res.setHeader('Content-Type', 'text/plain');
   switch (result) {
+    case 'redirecting':
+      res.setHeader('Location', info.location);
+      res.end('Redirecting...');
+      return;
     case 'accepted':
       res.end('Authentication successful! You can close this window now.');
       return;