feat: implement full bff logic
This commit is contained in:
Björn Fromme
@@ -0,0 +1,223 @@
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<?php
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namespace App\Controller;
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use App\Security\AppRegistry;
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use App\Security\IdTokenDecoder;
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use App\Session\BffSessionStore;
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use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
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use Symfony\Component\HttpFoundation\JsonResponse;
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use Symfony\Component\HttpFoundation\RedirectResponse;
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use Symfony\Component\HttpFoundation\Request;
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use Symfony\Component\HttpFoundation\Response;
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use Symfony\Component\Routing\Attribute\Route;
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use Symfony\Contracts\HttpClient\HttpClientInterface;
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class AuthController extends AbstractController
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{
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public function __construct(
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private readonly HttpClientInterface $client,
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private readonly BffSessionStore $store,
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private readonly IdTokenDecoder $idTokenDecoder,
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private readonly AppRegistry $apps,
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private readonly string $kcBaseUrl,
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private readonly string $kcRealm,
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private readonly string $kcClientId,
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private readonly string $kcClientSecret,
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private readonly string $kcRedirectUri,
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private readonly ?string $postLogoutRedirect = null,
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) {
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}
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/**
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* Entry point every app's login page navigates to (full browser
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* redirect, e.g. via Appsmith's navigateTo — never a fetch/query,
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* since Appsmith queries run server-side and can't perform this leg).
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*/
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#[Route('/auth/login', methods: ['GET'])]
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public function login(Request $request): RedirectResponse
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{
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$appKey = (string) $request->query->get('app', '');
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if (!$this->apps->isValidApp($appKey)) {
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throw $this->createNotFoundException('Unknown or missing app key');
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}
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$verifier = $this->base64UrlEncode(random_bytes(64));
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$challenge = $this->base64UrlEncode(hash('sha256', $verifier, true));
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$state = bin2hex(random_bytes(16));
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// Plain Symfony session cookie, used only for this short
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// browser <-> Keycloak <-> browser leg. Not the app's session.
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$session = $request->getSession();
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$session->set('pkce_verifier', $verifier);
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$session->set('oauth_state', $state);
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$session->set('oauth_app', $appKey);
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$params = http_build_query([
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'client_id' => $this->kcClientId,
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'response_type' => 'code',
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'scope' => 'openid profile email',
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'redirect_uri' => $this->kcRedirectUri,
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'state' => $state,
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'code_challenge' => $challenge,
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'code_challenge_method' => 'S256',
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]);
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return new RedirectResponse(
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"{$this->kcBaseUrl}/realms/{$this->kcRealm}/protocol/openid-connect/auth?{$params}"
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);
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}
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#[Route('/auth/callback', methods: ['GET'])]
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public function callback(Request $request): Response
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{
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$session = $request->getSession();
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$expectedState = (string) $session->get('oauth_state', '');
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$givenState = (string) $request->query->get('state', '');
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if ($expectedState === '' || !hash_equals($expectedState, $givenState)) {
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return new Response('Invalid or missing state', 401);
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}
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$appKey = (string) $session->get('oauth_app');
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$returnUrl = $this->apps->resolveReturnUrl($appKey);
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$requiredRole = $this->apps->requiredRole($appKey);
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$response = $this->client->request(
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'POST',
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"{$this->kcBaseUrl}/realms/{$this->kcRealm}/protocol/openid-connect/token",
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[
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'body' => [
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'grant_type' => 'authorization_code',
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'client_id' => $this->kcClientId,
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'client_secret' => $this->kcClientSecret,
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'code' => $request->query->get('code'),
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'redirect_uri' => $this->kcRedirectUri,
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'code_verifier' => $session->get('pkce_verifier'),
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],
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]
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);
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$tokens = $response->toArray();
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$idClaims = $this->idTokenDecoder->decode($tokens['id_token']);
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$kcSid = $idClaims['sid'] ?? null;
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if (!$kcSid) {
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throw new \RuntimeException('Keycloak did not issue a "sid" claim on the ID token');
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}
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// Authorization gate: does this user hold the role required for
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// the app they're trying to enter? Checked against the access
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// token (not the ID token), since that's where client roles live.
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// This is the only enforcement point — the proxy trusts any
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// already-established session, by design, since "may this user
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// use app X" is a login-time question, not a per-request one.
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$accessClaims = $this->idTokenDecoder->decode($tokens['access_token']);
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if (!$this->hasRole($accessClaims, $requiredRole)) {
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$session->remove('pkce_verifier');
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$session->remove('oauth_state');
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$session->remove('oauth_app');
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$separator = str_contains($returnUrl, '?') ? '&' : '?';
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return new RedirectResponse($returnUrl . $separator . http_build_query(['error' => 'access_denied']));
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}
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$session->remove('pkce_verifier');
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$session->remove('oauth_state');
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$session->remove('oauth_app');
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// Same kcSid -> same entry, whichever app is logging in. If another
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// app already created this session, this simply refreshes it.
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$this->store->put($kcSid, [
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'user_id' => $idClaims['sub'],
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'access_token' => $tokens['access_token'],
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'refresh_token' => $tokens['refresh_token'],
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'id_token' => $tokens['id_token'],
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'expires_at' => time() + (int) $tokens['expires_in'],
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'profile' => [
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'email' => $idClaims['email'] ?? null,
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'email_verified' => $idClaims['email_verified'] ?? null,
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'name' => $idClaims['name'] ?? null,
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'given_name' => $idClaims['given_name'] ?? null,
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'family_name' => $idClaims['family_name'] ?? null,
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'preferred_username' => $idClaims['preferred_username'] ?? null,
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],
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]);
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$separator = str_contains($returnUrl, '?') ? '&' : '?';
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return new RedirectResponse($returnUrl . $separator . http_build_query(['sid' => $kcSid]));
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}
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/** @param array<string,mixed> $accessTokenClaims */
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private function hasRole(array $accessTokenClaims, string $role): bool
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{
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$roles = $accessTokenClaims['resource_access'][$this->kcClientId]['roles'] ?? [];
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return in_array($role, $roles, true);
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}
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/**
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* Returns the logged-in user's profile (email, name, etc). Called by
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* an app as a normal API query with `Authorization: Bearer <sid>` —
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* same pattern as /api/*, but served directly by the BFF since this
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* data comes from the ID token, not the backend.
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*/
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#[Route('/auth/me', methods: ['GET'])]
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public function me(Request $request): JsonResponse
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{
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$kcSid = $this->extractBearer($request);
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if (!$kcSid) {
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return new JsonResponse(['error' => 'unauthenticated'], 401);
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}
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$session = $this->store->get($kcSid);
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if ($session === null) {
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return new JsonResponse(['error' => 'session expired'], 401);
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}
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return new JsonResponse($session['profile'] ?? []);
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}
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/**
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* Global logout. Called by an app as a normal (server-side-executed)
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* API query with `Authorization: Bearer <sid>`. Returns a URL rather
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* than redirecting itself, since the app must perform the actual
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* browser navigation to kill Keycloak's own SSO cookie.
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*/
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#[Route('/auth/logout', methods: ['POST'])]
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public function logout(Request $request): JsonResponse
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{
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$kcSid = $this->extractBearer($request);
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if (!$kcSid) {
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return new JsonResponse(['error' => 'missing session'], 401);
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}
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$data = $this->store->get($kcSid);
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$idToken = $data['id_token'] ?? null;
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// One delete kills the session for every app that shared it.
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$this->store->revoke($kcSid);
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$params = http_build_query(array_filter([
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'id_token_hint' => $idToken,
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'post_logout_redirect_uri' => $this->postLogoutRedirect,
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]));
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return new JsonResponse([
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'logout_url' => "{$this->kcBaseUrl}/realms/{$this->kcRealm}/protocol/openid-connect/logout?{$params}",
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]);
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}
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private function extractBearer(Request $request): ?string
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{
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$header = $request->headers->get('Authorization', '');
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return str_starts_with($header, 'Bearer ') ? substr($header, 7) : null;
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}
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private function base64UrlEncode(string $bytes): string
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{
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return rtrim(strtr(base64_encode($bytes), '+/', '-_'), '=');
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}
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}
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