[Plugins] [Auth] [oauth2] Support identity platforms with underlying IDPs (#261)

Co-authored-by: Gregory Schier <gschier1990@gmail.com>

plugins/auth-oauth2/src/util.ts

@@ -3,3 +3,83 @@ import type { AccessToken } from './store';
 export function isTokenExpired(token: AccessToken) {
   return token.expiresAt && Date.now() > token.expiresAt;
 }
+
+export function extractCode(urlStr: string, redirectUri: string | null): string | null {
+  const url = new URL(urlStr);
+
+  if (!urlMatchesRedirect(url, redirectUri)) {
+    console.log('[oauth2] URL does not match redirect origin/path; skipping.');
+    return null;
+  }
+
+  // Prefer query param; fall back to fragment if query lacks it
+
+  const query = url.searchParams;
+  const queryError = query.get('error');
+  const queryDesc = query.get('error_description');
+  const queryUri = query.get('error_uri');
+
+  let hashParams: URLSearchParams | null = null;
+  if (url.hash && url.hash.length > 1) {
+    hashParams = new URLSearchParams(url.hash.slice(1));
+  }
+  const hashError = hashParams?.get('error');
+  const hashDesc = hashParams?.get('error_description');
+  const hashUri = hashParams?.get('error_uri');
+
+  const error = queryError || hashError;
+  if (error) {
+    const desc = queryDesc || hashDesc;
+    const uri = queryUri || hashUri;
+    let message = `Failed to authorize: ${error}`;
+    if (desc) message += ` (${desc})`;
+    if (uri) message += ` [${uri}]`;
+    throw new Error(message);
+  }
+
+  const queryCode = query.get('code');
+  if (queryCode) return queryCode;
+
+  const hashCode = hashParams?.get('code');
+  if (hashCode) return hashCode;
+
+  console.log('[oauth2] Code not found');
+  return null;
+}
+
+export function urlMatchesRedirect(url: URL, redirectUrl: string | null): boolean {
+  if (!redirectUrl) return true;
+
+  let redirect;
+  try {
+    redirect = new URL(redirectUrl);
+  } catch {
+    console.log('[oauth2] Invalid redirect URI; skipping.');
+    return false;
+  }
+
+  const sameProtocol = url.protocol === redirect.protocol;
+
+  const sameHost = url.hostname.toLowerCase() === redirect.hostname.toLowerCase();
+
+  const normalizePort = (u: URL) =>
+    (u.protocol === 'https:' && (!u.port || u.port === '443')) ||
+    (u.protocol === 'http:' && (!u.port || u.port === '80'))
+      ? ''
+      : u.port;
+
+  const samePort = normalizePort(url) === normalizePort(redirect);
+
+  const normPath = (p: string) => {
+    const withLeading = p.startsWith('/') ? p : `/${p}`;
+    // strip trailing slashes, keep root as "/"
+    return withLeading.replace(/\/+$/g, '') || '/';
+  };
+
+  // Require redirect path to be a prefix of the navigated URL path
+  const urlPath = normPath(url.pathname);
+  const redirectPath = normPath(redirect.pathname);
+  const pathMatches = urlPath === redirectPath || urlPath.startsWith(`${redirectPath}/`);
+
+  return sameProtocol && sameHost && samePort && pathMatches;
+}