From e766658ee3b9e70988b79d99d75124857f2a7ccc Mon Sep 17 00:00:00 2001
From: Jeremy Shipman <jeremy@burnbright.net>
Date: Sat, 13 Jun 2015 12:12:36 +1200
Subject: [PATCH] API: Allow HTTP Cache Headers to be customized

---
 _config/config.yml |  7 ++++++-
 control/HTTP.php   | 21 ++++++++++++++++++---
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/_config/config.yml b/_config/config.yml
index a6fa72c8d..31dbd1682 100644
--- a/_config/config.yml
+++ b/_config/config.yml
@@ -5,4 +5,9 @@ Upload:
   # Replace an existing file rather than renaming the new one.
   replaceFile: false
 MySQLDatabase:
-  connection_charset: utf8
\ No newline at end of file
+  connection_charset: utf8
+HTTP:
+  cache_control:
+    max-age: 0
+    must-revalidate: "true"
+    no-transform: "true"
\ No newline at end of file
diff --git a/control/HTTP.php b/control/HTTP.php
index 83b5e6310..9993c8e52 100644
--- a/control/HTTP.php
+++ b/control/HTTP.php
@@ -330,10 +330,15 @@ class HTTP {
 
 		// Popuplate $responseHeaders with all the headers that we want to build
 		$responseHeaders = array();
+
 		$config = Config::inst();
+		$cacheControlHeaders = Config::inst()->get('HTTP', 'cache_control');
+
+
 		// currently using a config setting to cancel this, seems to be so taht the CMS caches ajax requests
 		if(function_exists('apache_request_headers') && $config->get(get_called_class(), 'cache_ajax_requests')) {
 			$requestHeaders = apache_request_headers();
+
 			if(isset($requestHeaders['X-Requested-With']) && $requestHeaders['X-Requested-With']=='XMLHttpRequest') {
 				$cacheAge = 0;
 			}
@@ -344,7 +349,7 @@ class HTTP {
 		}
 
 		if($cacheAge > 0) {
-			$responseHeaders["Cache-Control"] = "max-age={$cacheAge}, must-revalidate, no-transform";
+			$cacheControlHeaders['max-age'] = self::$cache_age;
 			$responseHeaders["Pragma"] = "";
 
 			// To do: User-Agent should only be added in situations where you *are* actually
@@ -368,10 +373,20 @@ class HTTP {
 				// IE6-IE8 have problems saving files when https and no-cache are used
 				// (http://support.microsoft.com/kb/323308)
 				// Note: this is also fixable by ticking "Do not save encrypted pages to disk" in advanced options.
-				$responseHeaders["Cache-Control"] = "max-age=3, must-revalidate, no-transform";
+				$cacheControlHeaders['max-age'] = 3;
 				$responseHeaders["Pragma"] = "";
 			} else {
-				$responseHeaders["Cache-Control"] = "no-cache, max-age=0, must-revalidate, no-transform";
+				$cacheControlHeaders['no-cache'] = "true";
+			}
+		}
+
+		foreach($cacheControlHeaders as $header => $value) {
+			if(is_null($value)) {
+				unset($cacheControlHeaders[$header]);
+			} elseif(is_bool($value) || $value === "true") {
+				$cacheControlHeaders[$header] = $header;
+			} else {
+				$cacheControlHeaders[$header] = $header."=".$value;
 			}
 		}