fix: discover OIDC metadata server-side to avoid CORS failures #382

app/(main)/[locale]/login/page.tsx

@@ -14,7 +14,7 @@ import { useConfig } from "@/hooks/use-config";
 import { apiFetch, getPathPrefix, withBasePath } from "@/lib/browser-navigation";
 import { cn } from "@/lib/utils";
 import { AlertCircle, Loader2, X, Info, Eye, EyeOff, LogIn, Sun, Moon, Monitor, Check, Shield, Play, Copy } from "lucide-react";
-import { discoverOAuth, type OAuthMetadata } from "@/lib/oauth/discovery";
+import { type OAuthMetadata } from "@/lib/oauth/discovery";
 import { generateCodeVerifier, generateCodeChallenge, generateState } from "@/lib/oauth/pkce";
 import { useUpdateStore, selectBanner } from "@/stores/update-store";
 import type { PublicJmapServerEntry } from "@/lib/admin/jmap-servers";
@@ -329,16 +329,27 @@ export default function LoginPage() {
     if (!oauthEnabled || !serverUrl) return;
     setOauthDiscoveryDone(false);
     setOauthMetadata(null);
-    discoverOAuth(effectiveOauthIssuerUrl || serverUrl)
+    const controller = new AbortController();
+    // Discover via our own origin rather than fetching the IdP's /.well-known/*
+    // documents directly from the browser. A direct cross-origin discovery
+    // fetch is subject to CORS, and providers like Authentik serve those
+    // documents without Access-Control-Allow-Origin, so the browser blocks the
+    // response and login breaks (issue #382). The proxy runs discovery server
+    // side where CORS does not apply.
+    const query = selectedServer?.id ? `?server_id=${encodeURIComponent(selectedServer.id)}` : "";
+    apiFetch(`/api/auth/oauth/metadata${query}`, { signal: controller.signal })
+      .then(async (res) => (res.ok ? ((await res.json()) as OAuthMetadata) : null))
       .then((metadata) => {
         setOauthMetadata(metadata);
         setOauthDiscoveryDone(true);
       })
-      .catch(() => {
+      .catch((err) => {
+        if (err?.name === "AbortError") return;
         setOauthMetadata(null);
         setOauthDiscoveryDone(true);
       });
-  }, [oauthEnabled, serverUrl, effectiveOauthIssuerUrl]);
+    return () => controller.abort();
+  }, [oauthEnabled, serverUrl, effectiveOauthIssuerUrl, selectedServer?.id]);
 
   // Auto-SSO: when enabled with OAUTH_ONLY, skip the login page entirely
   const ssoError = searchParams.get("sso_error");