1 files changed, 129 insertions, 0 deletions
diff --git a/system/helpers/expires.php b/system/helpers/expires.php
new file mode 100644
index 0000000..a3e01b8
--- /dev/null
+++ b/system/helpers/expires.php
@@ -0,0 +1,129 @@
+<?php defined('SYSPATH') OR die('No direct access allowed.');
+/**
+ * Controls headers that effect client caching of pages
+ *
+ * @package    Kohana
+ * @author     Kohana Team
+ * @copyright  (c) 2007-2009 Kohana Team
+ * @license    http://kohanaphp.com/license
+ */
+class expires_Core {
+
+	/**
+	 * Sets the amount of time before content expires
+	 *
+	 * @param   integer Seconds before the content expires
+	 * @param   integer Last modified timestamp in seconds(optional)
+ 	 * @return  integer Timestamp when the content expires
+	 */
+	public static function set($seconds = 60, $last_modified=null)
+	{
+		$now = time();
+		$expires = $now + $seconds;
+ 		if (empty($last_modified))
+ 		{
+ 			$last_modified = $now;
+ 		}
+
+ 		 header('Last-Modified: '.gmdate('D, d M Y H:i:s T', $last_modified));
+
+		// HTTP 1.0
+		header('Expires: '.gmdate('D, d M Y H:i:s T', $expires));
+
+		// HTTP 1.1
+		header('Cache-Control: public,max-age='.$seconds);
+
+		return $expires;
+	}
+
+	/**
+	 * Parses the If-Modified-Since header
+	 *
+	 * @return  integer|boolean Timestamp or FALSE when header is lacking or malformed
+	 */
+	public static function get()
+	{
+		if ( ! empty($_SERVER['HTTP_IF_MODIFIED_SINCE']))
+		{
+			// Some versions of IE6 append "; length=####"
+			if (($strpos = strpos($_SERVER['HTTP_IF_MODIFIED_SINCE'], ';')) !== FALSE)
+			{
+				$mod_time = substr($_SERVER['HTTP_IF_MODIFIED_SINCE'], 0, $strpos);
+			}
+			else
+			{
+				$mod_time = $_SERVER['HTTP_IF_MODIFIED_SINCE'];
+			}
+
+			return strtotime($mod_time);
+		}
+
+		return FALSE;
+	}
+
+	/**
+	 * Checks to see if content should be updated otherwise sends Not Modified status
+	 * and exits.
+	 *
+	 * @uses    exit()
+	 * @uses    expires::get()
+	 *
+	 * @param   integer         Maximum age of the content in seconds
+	 * @param   integer Last modified timestamp in seconds(optional)
+	 * @return  integer|boolean Timestamp of the If-Modified-Since header or FALSE when header is lacking or malformed
+	 */
+	public static function check($seconds = 60, $modified=null)
+	{
+		if ($last_modified = expires::get())
+		{
+			$now = time();
+
+ 			if (empty($last_modified))
+ 			{
+ 				$last_modified = $now;
+ 			}
+
+			if ($modified <= $last_modified)
+			{
+				// Content has not expired
+				header($_SERVER['SERVER_PROTOCOL'].' 304 Not Modified');
+				header('Last-Modified: '.gmdate('D, d M Y H:i:s T', $last_modified));
+
+				$expires = $now + $seconds;
+				// HTTP 1.0
+				header('Expires: '.gmdate('D, d M Y H:i:s T', $expires));
+
+				// HTTP 1.1
+				header('Cache-Control: public,max-age='.$seconds);
+
+				// Clear any output
+				Event::add('system.display', create_function('', 'Kohana::$output = "";'));
+
+				exit;
+			}
+		}
+
+		return $last_modified;
+	}
+
+	/**
+	 * Check if expiration headers are already set
+	 *
+	 * @return boolean
+	 */
+	public static function headers_set()
+	{
+		foreach (headers_list() as $header)
+		{
+			if (strncasecmp($header, 'Expires:', 8) === 0
+				OR strncasecmp($header, 'Cache-Control:', 14) === 0
+				OR strncasecmp($header, 'Last-Modified:', 14) === 0)
+			{
+				return TRUE;
+			}
+		}
+
+		return FALSE;
+	}
+
+} // End expires