string $maybe_ip A suspected IP address. * @return int|false Upon success, '4' or '6' to represent an IPv4 or IPv6 address, false upon failure. */ public static function is_ip_address( $maybe_ip ) { if ( preg_match( '/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/', $maybe_ip ) ) { return 4; } if ( str_contains( $maybe_ip, ':' ) && preg_match( '/^(((?=.*(::))(?!.*\3.+\3))\3?|([\dA-F]{1,4}(\3|:\b|$)|\2))(?4){5}((?4){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4})$/i', trim( $maybe_ip, ' []' ) ) ) { return 6; } return false; } }