From 0d084cd5464fd630bc347bec8714883d42b6bc10 Mon Sep 17 00:00:00 2001
From: Simon Franken <mail@simon-franken.de>
Date: Wed, 18 Feb 2026 22:45:38 +0100
Subject: [PATCH] update

---
 backend/src/routes/auth.routes.ts | 56 ++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 19 deletions(-)

diff --git a/backend/src/routes/auth.routes.ts b/backend/src/routes/auth.routes.ts
index 0609093..b2a3b6a 100644
--- a/backend/src/routes/auth.routes.ts
+++ b/backend/src/routes/auth.routes.ts
@@ -7,7 +7,8 @@ import {
   getUserInfo,
 } from "../auth/oidc";
 import { requireAuth, syncUser } from "../middleware/auth";
-import type { AuthenticatedRequest } from "../types";
+import type { AuthenticatedRequest, AuthenticatedUser } from "../types";
+import type { AuthSession } from "../auth/oidc";
 
 const router = Router();
 
@@ -21,6 +22,26 @@ async function ensureOIDC() {
   }
 }
 
+// Short-lived store for native app OIDC sessions, keyed by state.
+// Entries are cleaned up after 10 minutes regardless of use.
+const nativeOidcSessions = new Map<string, { session: AuthSession; expiresAt: number }>();
+const NATIVE_SESSION_TTL_MS = 10 * 60 * 1000;
+
+function storeNativeSession(session: AuthSession): void {
+  nativeOidcSessions.set(session.state, {
+    session,
+    expiresAt: Date.now() + NATIVE_SESSION_TTL_MS,
+  });
+}
+
+function popNativeSession(state: string): AuthSession | null {
+  const entry = nativeOidcSessions.get(state);
+  if (!entry) return null;
+  nativeOidcSessions.delete(state);
+  if (Date.now() > entry.expiresAt) return null;
+  return entry.session;
+}
+
 // GET /auth/login - Initiate OIDC login flow
 router.get("/login", async (req, res) => {
   try {
@@ -28,7 +49,15 @@ router.get("/login", async (req, res) => {
 
     const redirectUri = req.query.redirect_uri as string | undefined;
     const session = createAuthSession(redirectUri);
-    req.session.oidc = session;
+
+    if (redirectUri) {
+      // Native app flow: store session by state so /auth/token can retrieve it
+      // without relying on the browser cookie jar.
+      storeNativeSession(session);
+    } else {
+      // Web flow: store session in the cookie-backed server session as before.
+      req.session.oidc = session;
+    }
 
     const authorizationUrl = getAuthorizationUrl(session, redirectUri);
     res.redirect(authorizationUrl);
@@ -38,7 +67,7 @@ router.get("/login", async (req, res) => {
   }
 });
 
-// GET /auth/callback - OIDC callback handler
+// GET /auth/callback - OIDC callback handler (web frontend only)
 router.get("/callback", async (req, res) => {
   try {
     await ensureOIDC();
@@ -89,9 +118,9 @@ router.get("/me", requireAuth, (req: AuthenticatedRequest, res) => {
   res.json(req.user);
 });
 
-// POST /auth/token - Exchange authorization code for tokens (for native apps)
-// The session cookie set during /auth/login is sent automatically by ASWebAuthenticationSession,
-// so req.session.oidc contains the original state/nonce for validation.
+// POST /auth/token - Exchange authorization code for tokens (native app flow)
+// Session state is retrieved from the in-memory store by state value, so no
+// session cookie is required from the native client.
 router.post("/token", async (req, res) => {
   try {
     await ensureOIDC();
@@ -103,20 +132,12 @@ router.post("/token", async (req, res) => {
       return;
     }
 
-    const oidcSession = req.session.oidc;
+    const oidcSession = popNativeSession(state);
     if (!oidcSession) {
-      res.status(400).json({ error: "No active OIDC session. Initiate login first." });
+      res.status(400).json({ error: "OIDC session not found or expired. Initiate login again." });
       return;
     }
 
-    // Validate that the returned state matches what was stored in the session
-    if (oidcSession.state !== state) {
-      res.status(400).json({ error: "State mismatch" });
-      return;
-    }
-
-    // Use the session's own codeVerifier (generated by the backend during /auth/login)
-    // rather than a client-supplied one, to prevent verifier substitution attacks.
     const session = {
       codeVerifier: oidcSession.codeVerifier,
       state: oidcSession.state,
@@ -129,9 +150,6 @@ router.post("/token", async (req, res) => {
     const user = await getUserInfo(tokenSet);
     await syncUser(user);
 
-    // Clear OIDC session state now that it has been consumed
-    delete req.session.oidc;
-
     res.json({
       access_token: tokenSet.access_token,
       id_token: tokenSet.id_token,