Secure PHP Session - PHP

/**
 * Our custom way of starting a secure session
 *
 * Preventing session ID passing as a GET parameter, only send (session)cookie over HTTPS,
 * protection against XSS attacks (HTTP Only), session fixation and session hijacking.
 */
function sec_session_start() {
    // Forces sessions to only use cookies (disallow session ID passing as a GET parameter).
    if (ini_set('session.use_only_cookies', 1) === FALSE) {
        echo "Could not initiate a safe session (ini_set)";
        exit();
    }

    $session_name = "xIhFr7bkA5d1y6"; // Set your custom session name.
    $domain = ".mydomain.com"; // The dot makes the (session)cookie available for subdomains too. Change to your domain.
    $secure = TRUE; // If TRUE, (session)cookie will only be sent over secure (HTTPS) connections.
    $http_only = TRUE; // If TRUE, prevents JavaScript being able to access the session id.

    // Gets current cookies params.
    $cookieParams = session_get_cookie_params();
    session_set_cookie_params($cookieParams["lifetime"], $cookieParams["path"], $domain, $secure, $http_only);

    // Sets the session name to the one set in config
    session_name($session_name);

    // Start the PHP session
    session_start();

    // Protection against session fixation and hijacking attacks.
    if (!isset($_SESSION['canary'])) {
        session_regenerate_id(true);
        $_SESSION['canary'] = [
            'birth' => time(),
            'browser' => hash('md5', $_SERVER['HTTP_USER_AGENT'])
        ];
    }
    if ($_SESSION['canary']['browser'] !== hash('md5', $_SERVER['HTTP_USER_AGENT'])) {
        session_regenerate_id(true);
        // Delete everything:
        foreach (array_keys($_SESSION) as $key) {
            unset($_SESSION[$key]);
        }
        $_SESSION['canary'] = [
            'birth' => time(),
            'browser' => hash('md5', $_SERVER['HTTP_USER_AGENT'])
        ];
    }
    // Regenerate session ID every five minutes:
    if ($_SESSION['canary']['birth'] < time() - 300) {
        session_regenerate_id(true);
        $_SESSION['canary']['birth'] = time();
    }
}