View file test.4imas.ru/config/csrf.php

<?php

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

if (empty($_SESSION['csrf_token'])) {
    $_SESSION['csrf_token'] = bin2hex(random_bytes(32));
}
define('CSRF_TOKEN', $_SESSION['csrf_token']);

function csrf_input() {
    return '<input type="hidden" name="csrf" value="' . e(CSRF_TOKEN) . '">';
}

function check_csrf($token) {
    return isset($_SESSION['csrf_token']) && hash_equals($_SESSION['csrf_token'], $token);
}

function e($string) {
    return htmlspecialchars($string ?? '', ENT_QUOTES, 'UTF-8');
}

function require_csrf() {
    if ($_SERVER['REQUEST_METHOD'] === 'POST') {
        $token = $_POST['csrf'] ?? '';
        if (!check_csrf($token)) {
            http_response_code(403);
            die('Ошибка безопасности (CSRF).');
        }
    }
}
?>