$LastModified_unix = strtotime(date("D, d M Y H:i:s", filectime($_SERVER['SCRIPT_FILENAME']))); $LastModified = gmdate("D, d M Y H:i:s \G\M\T", $LastModified_unix); $IfModifiedSince = false;
if (isset($_ENV['HTTP_IF_MODIFIED_SINCE'])) $IfModifiedSince = strtotime(substr($_ENV['HTTP_IF_MODIFIED_SINCE'], 5));
if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) $IfModifiedSince = strtotime(substr($_SERVER['HTTP_IF_MODIFIED_SINCE'], 5));
if ($IfModifiedSince && $IfModifiedSince >= $LastModified_unix) { header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified'); exit; }