From 9aab17be924ec04b7b46a971d3c9f414f6eb9bf0 Mon Sep 17 00:00:00 2001
From: Urban Müller
Date: Wed, 28 Oct 2015 18:51:39 +0100
Subject: extract far future header handling for ffe.php

---
 itjs.class | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'itjs.class')

diff --git a/itjs.class b/itjs.class
index b8520f5..f76620f 100644
--- a/itjs.class
+++ b/itjs.class
@@ -217,6 +217,26 @@ function crcurl($url)
 	return it::match('#', $url) ? U(trim($url, "#")) : U($url, array('c' => self::checksum(array($fn))));
 }
 
+static function far_future_headers()
+{
+	$crc = $_REQUEST['c'] ?: $_REQUEST['s'];
+	if ($crc != "-" && !$_SERVER['HTTP_CACHE_CONTROL'] && $_SERVER['HTTP_IF_NONE_MATCH'] && !it::is_devel() && !$_REQUEST['retry'])
+	{
+		header("HTTP/1.0 304 Not Modified"); # client should always keep the component that fits the page it has
+		exit;
+	}
+
+	if ($crc != "-")
+		@header("Etag: alwaysvalid"); # we have checksums in the url. client should always keep the version he downloaded along with the html
+
+	if (it::is_live() && !$_REQUEST['retry'])
+	{
+		$keeptime = $crc == "-" ? 0 : ($crc ? 30*86400 : 900); # long expire if checksum present
+		header("Cache-Control: max-age=$keeptime, private"); # proxies should not cache since contents of same url can differ between browsers
+		header("Expires: " . gmdate("D, d M Y H:i:s", time() + $keeptime). " GMT");
+	}
+}
+
 }
 
 ?>
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