blackwall-auth-sdk/docs/INTEGRATION_GUIDE.md

Integration Guide (British English)

This guide shows a complete OAuth/OIDC login flow using BlackWall\Auth\AuthClient.

1. Start login

<?php

declare(strict_types=1);

session_start();
require __DIR__ . '/vendor/autoload.php';

use BlackWall\Auth\AuthClient;
use BlackWall\Auth\Config;

$client = new AuthClient(Config::fromArray([
    'clientId' => 'your-client-id',
    'authorizeUrl' => 'https://blackwall.cx/oauth/authorize',
    'tokenUrl' => 'https://blackwall.cx/oauth/token',
    'userInfoUrl' => 'https://blackwall.cx/oauth/userinfo',
    'redirectUri' => 'https://your-app.example/callback.php',
    'scope' => 'openid profile email offline_access',
]));

if (!isset($_SESSION['user'])) {
    $auth = $client->buildAuthorisationUrl([
        'extra' => [
            // Some providers require nonce for OIDC requests.
            'nonce' => rtrim(strtr(base64_encode(random_bytes(32)), '+/', '-_'), '='),
        ],
    ]);
    // Prevent stale redirects from being reused from cache.
    header('Cache-Control: no-store, no-cache, must-revalidate, max-age=0');
    header('Pragma: no-cache');
    header('Location: ' . $auth['url']);
    exit;
}

echo 'Already signed in.';

2. Handle callback

<?php

declare(strict_types=1);

session_start();
require __DIR__ . '/vendor/autoload.php';

use BlackWall\Auth\AuthClient;
use BlackWall\Auth\Config;

$client = new AuthClient(Config::fromArray([
    'clientId' => 'your-client-id',
    'authorizeUrl' => 'https://blackwall.cx/oauth/authorize',
    'tokenUrl' => 'https://blackwall.cx/oauth/token',
    'userInfoUrl' => 'https://blackwall.cx/oauth/userinfo',
    'redirectUri' => 'https://your-app.example/callback.php',
]));

if (isset($_GET['error'])) {
    $error = (string) $_GET['error'];
    $description = isset($_GET['error_description']) ? (string) $_GET['error_description'] : 'Unknown provider error';
    // access_denied is a normal authorisation outcome (for example, membership
    // revoked, privilege changed, or user denied consent between request and submit).
    http_response_code($error === 'access_denied' ? 403 : 400);
    exit('Authorization failed: ' . $description);
}

$result = $client->handleCallback($_GET);

$_SESSION['user'] = [
    'email' => $result->user->email,
    'privilege_level' => $result->user->privilegeLevel,
    'role' => $result->user->role,
];
$_SESSION['access_token'] = $result->tokens->accessToken;
$_SESSION['refresh_token'] = $result->tokens->refreshToken;

header('Location: /');
exit;

3. Single callback for multiple app roles

Using one OAuth client and one callback URL is recommended.

Map users in your application by:

1. email claim to local account record
2. privilege_level (or role) to application role

Typical mapping example:

• privilege_level = 1 => admin/superadmin
• privilege_level = 2 => user/tutor

If privilege_level is absent, the SDK also resolves common role strings (admin, superadmin, user, tutor).

4. Refresh token (optional)

<?php

$tokens = $client->refreshAccessToken($_SESSION['refresh_token']);
$_SESSION['access_token'] = $tokens->accessToken;
if ($tokens->refreshToken !== null) {
    $_SESSION['refresh_token'] = $tokens->refreshToken;
}

Exceptions

Catch specific exceptions for clearer handling:

• BlackWall\Auth\Exception\StateMismatchException
• BlackWall\Auth\Exception\TokenExchangeException
• BlackWall\Auth\Exception\UserInfoException
• BlackWall\Auth\Exception\TransportException

Example:

try {
    $tokens = $client->exchangeCodeForTokens($code);
} catch (\BlackWall\Auth\Exception\TokenExchangeException $e) {
    error_log('Token exchange failed: ' . $e->getMessage());
    error_log('Auth code: ' . ($e->authCode() ?? 'none'));
    http_response_code(502);
}

UserInfoException with invalid_token can occur when provider-side subject scope is no longer active (for example user/project disabled) between token issuance and userinfo retrieval. TokenExchangeException with invalid_grant can also occur when provider-side client/user/project state is inactive at exchange time. Provider login/authorization steps can also fail with access_denied when account status is disabled before completion. WebAuthn-based login verification can return credential-style failures for disabled accounts even when authenticator assertions are otherwise valid. Existing authenticated sessions may also be invalidated when account status changes to disabled. OAuth authorization consent submission can return access_denied if the account becomes inactive between session establishment and consent completion. Provider user/project assignment views may exclude disabled projects even if historical assignments exist.

Operational guidance

• Keep provider URLs in environment variables, not hard-coded.
• Avoid printing tokens in production pages.
• Expect 429 Too Many Requests from provider control endpoints under abuse protection; implement backoff/retry instead of tight loops.
• Apply the same backoff strategy for provider userinfo calls that return 429 Too Many Requests.
• For token exchange and refresh, apply bounded retry/backoff on transient provider failures instead of immediate repeated retries.
• Use exactly one client authentication method per token/control request (do not send both HTTP Basic and client_secret form fields together).
• If you call provider WebAuthn login challenge/verify endpoints directly, use POST only.
• Treat admin enrollment URL export as a state-changing operation: call it with POST and include a valid CSRF token.
• Configure OAuth client redirect URIs as HTTPS in production; reserve HTTP for localhost loopback testing only.
• Assume provider rate limits are enforced per source identity (for example IP) and shared across related auth endpoints.
• Treat report/export-style provider endpoints as high-cost and expect stricter rate limits.
• Rotate client secrets for confidential clients.
• Do not transport secrets or tokens in URL query parameters; keep them in server-side session or secure storage only.
• Add a unique nonce to each OIDC authorisation request.
• Keep state, nonce, and PKCE values within standard URL-safe formats/lengths; malformed values can be rejected by provider validation.
• Validate state on every callback request.
• Use secure session cookies (Secure, HttpOnly, SameSite=Lax or stricter).
• HTTPS URLs are enforced by default in Config::fromArray().
• For localhost-only HTTP testing, explicitly set allowInsecureHttp => true.
• If you call Cryptbin unwrap APIs directly, include the original share key as key_b64url; unwrap now returns 403 Forbidden when key proof does not match metadata verifier.