Zend\Diactoros\HeaderSecurity::isValid PHP 메소드

    public static function isValid($value)
    {
        $value = (string) $value;
        // Look for:
        // \n not preceded by \r, OR
        // \r not followed by \n, OR
        // \r\n not followed by space or horizontal tab; these are all CRLF attacks
        if (preg_match("#(?:(?:(?<!\r)\n)|(?:\r(?!\n))|(?:\r\n(?![ \t])))#", $value)) {
            return false;
        }
        // Non-visible, non-whitespace characters
        // 9 === horizontal tab
        // 10 === line feed
        // 13 === carriage return
        // 32-126, 128-254 === visible
        // 127 === DEL (disallowed)
        // 255 === null byte (disallowed)
        if (preg_match('/[^\\x09\\x0a\\x0d\\x20-\\x7E\\x80-\\xFE]/', $value)) {
            return false;
        }
        return true;
    }