diff options
| -rw-r--r-- | app/df.php | 24 |
1 files changed, 17 insertions, 7 deletions
@@ -31,24 +31,34 @@ require_once "class/mesg.class.php"; /* * Serve the resource at the given URI in response to the current * request. When finished, this function will exit PHP and terminate - * this script. The response instructs the client to cache the - * result for 24 hours. + * this script. */ function serveResource(string $uri, ?string $filename = NULL) : void { $f = fopen($uri, "rb"); + /* no file */ if (!$f) exit; - $cachelen = 86400; // secs, 24-hours - $cachedate = gmdate("D, d M Y H:i:s", time() + $cachelen); + /* enable client caching */ + header("Cache-Control: max-age=0"); + header("Pragma: cache"); + + $hash = hash_file("sha256", $uri); + /* validate client cache */ + if (isset($_SERVER['HTTP_IF_NONE_MATCH']) && + $_SERVER['HTTP_IF_NONE_MATCH'] == $hash) + { + header("HTTP/1.1 304 Not Modified"); + exit; + } + + /* resource metadata */ header("Content-Type: " . mime_content_type($uri)); header("Content-Length: " . filesize($uri)); - header("Expires: " . $cachedate); - header("Cache-Control: max-age=" . $cachelen); - header("Pragma: cache"); + header("ETag: " . $hash); if ($filename) header("Content-Disposition: attachment; filename=\"" . $filename . "\""); |