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.

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.
• 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.
• 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.
• 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.