<?php
namespace Packback\Lti1p3;
use Packback\Lti1p3\Interfaces\ICache;
use Packback\Lti1p3\Interfaces\ICookie;
use Packback\Lti1p3\Interfaces\IDatabase;
class LtiOidcLogin
{
public const COOKIE_PREFIX = 'lti1p3_';
<
public const ERROR_MSG_LAUNCH_URL = 'No launch URL configured';
public const ERROR_MSG_ISSUER = 'Could not find issuer';
public const ERROR_MSG_LOGIN_HINT = 'Could not find login hint';
< public const ERROR_MSG_REGISTRATION = 'Could not find registration details';
<
private $db;
private $cache;
private $cookie;
/**
* Constructor.
*
< * @param IDatabase $database instance of the database interface used for looking up registrations and deployments
< * @param ICache $cache Instance of the Cache interface used to loading and storing launches. If non is provided launch data will be store in $_SESSION.
< * @param ICookie $cookie Instance of the Cookie interface used to set and read cookies. Will default to using $_COOKIE and setcookie.
> * @param IDatabase $database Instance of the Database interface used for looking up registrations and deployments
> * @param ICache $cache instance of the Cache interface used to loading and storing launches
> * @param ICookie $cookie instance of the Cookie interface used to set and read cookies
*/
public function __construct(IDatabase $database, ICache $cache = null, ICookie $cookie = null)
{
$this->db = $database;
$this->cache = $cache;
$this->cookie = $cookie;
}
/**
* Static function to allow for method chaining without having to assign to a variable first.
*/
public static function new(IDatabase $database, ICache $cache = null, ICookie $cookie = null)
{
return new LtiOidcLogin($database, $cache, $cookie);
}
/**
* Calculate the redirect location to return to based on an OIDC third party initiated login request.
*
* @param string $launch_url URL to redirect back to after the OIDC login. This URL must match exactly a URL white listed in the platform.
* @param array|string $request An array of request parameters. If not set will default to $_REQUEST.
< *
* @return Redirect returns a redirect object containing the fully formed OIDC login URL
*/
public function doOidcLoginRedirect($launch_url, array $request = null)
{
if ($request === null) {
$request = $_REQUEST;
}
if (empty($launch_url)) {
throw new OidcException(static::ERROR_MSG_LAUNCH_URL, 1);
}
// Validate Request Data.
$registration = $this->validateOidcLogin($request);
/*
* Build OIDC Auth Response.
*/
// Generate State.
// Set cookie (short lived)
$state = static::secureRandomString('state-');
$this->cookie->setCookie(static::COOKIE_PREFIX.$state, $state, 60);
// Generate Nonce.
$nonce = static::secureRandomString('nonce-');
$this->cache->cacheNonce($nonce, $state);
// Build Response.
$auth_params = [
'scope' => 'openid', // OIDC Scope.
'response_type' => 'id_token', // OIDC response is always an id token.
'response_mode' => 'form_post', // OIDC response is always a form post.
'prompt' => 'none', // Don't prompt user on redirect.
'client_id' => $registration->getClientId(), // Registered client id.
'redirect_uri' => $launch_url, // URL to return to after login.
'state' => $state, // State to identify browser session.
'nonce' => $nonce, // Prevent replay attacks.
'login_hint' => $request['login_hint'], // Login hint to identify platform session.
];
// Pass back LTI message hint if we have it.
if (isset($request['lti_message_hint'])) {
// LTI message hint to identify LTI context within the platform.
$auth_params['lti_message_hint'] = $request['lti_message_hint'];
}
$auth_login_return_url = $registration->getAuthLoginUrl().'?'.http_build_query($auth_params, '', '&');
// Return auth redirect.
return new Redirect($auth_login_return_url, http_build_query($request, '', '&'));
}
public function validateOidcLogin($request)
{
// Validate Issuer.
if (empty($request['iss'])) {
throw new OidcException(static::ERROR_MSG_ISSUER, 1);
}
// Validate Login Hint.
if (empty($request['login_hint'])) {
throw new OidcException(static::ERROR_MSG_LOGIN_HINT, 1);
}
// Fetch Registration Details.
< $registration = $this->db->findRegistrationByIssuer($request['iss'], $request['client_id'] ?? null);
> $clientId = $request['client_id'] ?? null;
> $registration = $this->db->findRegistrationByIssuer($request['iss'], $clientId);
// Check we got something.
if (empty($registration)) {
< throw new OidcException(static::ERROR_MSG_REGISTRATION, 1);
> $errorMsg = LtiMessageLaunch::getMissingRegistrationErrorMsg($request['iss'], $clientId);
>
> throw new OidcException($errorMsg, 1);
}
// Return Registration.
return $registration;
}
public static function secureRandomString(string $prefix = ''): string
{
return $prefix.hash('sha256', random_bytes(64));
}
}