Add two-factor authentication

- Add 2FA login interception in Session::setAuthenticatedForUser
- Add 2fa session variable holding the last auth code

src/Core/Authentication.php

@@ -5,6 +5,7 @@
 
 namespace Friendica\Core;
 
+use Friendica\App;
 use Friendica\BaseObject;
 use Friendica\Util\BaseURL;
 
@@ -61,5 +62,26 @@ class Authentication extends BaseObject
 		session_unset();
 		session_destroy();
 	}
+
+	public static function twoFactorCheck($uid, App $a)
+	{
+		// Check user setting, if 2FA disabled return
+		if (!PConfig::get($uid, '2fa', 'verified')) {
+			return;
+		}
+
+		// Check current path, if 2fa authentication module return
+		if ($a->argc > 0 && in_array($a->argv[0], ['ping', '2fa', 'view', 'help', 'logout'])) {
+			return;
+		}
+
+		// Case 1: 2FA session present and valid: return
+		if (Session::get('2fa')) {
+			return;
+		}
+
+		// Case 2: No valid 2FA session: redirect to code verification page
+		$a->internalRedirect('2fa');
+	}
 }
 

src/Core/Session.php

@@ -186,6 +186,8 @@ class Session
 			}
 		}
 
+		Authentication::twoFactorCheck($user_record['uid'], $a);
+
 		if ($interactive) {
 			if ($user_record['login_date'] <= DBA::NULL_DATETIME) {
 				info(L10n::t('Welcome %s', $user_record['username']));