added a caching api proxy (that also validates the client IPs) for dozmod.

2 files changed, 83 insertions, 6 deletions

diff --git a/config.php.example b/config.php.example
index 6674ef61..14978897 100644
--- a/config.php.example
+++ b/config.php.example
@@ -26,10 +26,13 @@ define('CONFIG_VMSTORE_DIR', '/srv/openslx/nfs');
 
 define('CONFIG_PROXY_CONF', '/opt/openslx/proxy/config');
 
+/* for the dozmod API proxy cache */ 
+define('CONFIG_DOZMOD_EXPIRE', 60*60); // 1 Minute
+
 // Sort order for menu - optional, if missing, order will be alphabetically
 $MENU_CAT_SORT_ORDER = array('main.content' => 0, 'main.settings-client' => 1, 'main.settings-server' => 2, 'main.status' => 3, 'main.users' => 4);
 $MENU_SETTING_SORT_ORDER = array(
 	'news' => 0, 'sysconfig' => 1, 'baseconfig' => 2, 'locations' => 3, // main.content
 	'serversetup' => 0, 'internetaccess' => 1, 'vmstore' => 2, 'webinterface' => 3, 'backup' => 4, // main.settings
 	'systemstatus' => 0, 'eventlog' => 1, 'syslog' => 2, 'statistics' => 3 // main.status
-);
\ No newline at end of file
+);
diff --git a/modules-available/dozmod/api.inc.php b/modules-available/dozmod/api.inc.php
index f5525ef8..569b60a8 100644
--- a/modules-available/dozmod/api.inc.php
+++ b/modules-available/dozmod/api.inc.php
@@ -1,11 +1,64 @@
 <?php 
-/* Hier kommt der Dozmod proxy hin */
+/* small API server that acts as a proxy to the dozmod server.
+ * To reduce the number of requests and connections to dozmod-server, results
+ * gets cached into a file cache.
+ *
+ * Required Configuration:
+ * CONFIG_DOZMOD_EXPIRE: Expiration time in seconds for the cache
+ * CONFIG_DOZMOD: URL to the dozmod server
+ * 
+ **/
+
 require 'modules/locations/inc/location.inc.php';
 
+
 define('LIST_URL', CONFIG_DOZMOD . '/vmchooser/list');
 define('VMX_URL', CONFIG_DOZMOD . '/vmchooser/lecture');
 $availableRessources = ['vmx', 'test', 'netrules'];
 
+/* BEGIN: A simple caching mechanism ---------------------------- */
+
+function cache_hash($obj) {
+    return md5(serialize($obj)); 
+}
+
+function cache_key_to_filename($key) {
+    return "/tmp/bwlp-slxadmin-cache-$key"; // TODO: hash
+}
+
+function cache_put($key, $value) {
+    $filename = cache_key_to_filename($key);
+    file_put_contents($filename, $value);
+}
+
+function cache_has($key) {
+    $filename = cache_key_to_filename($key);
+    $mtime = filemtime($filename);
+
+    if (!$mtime) {
+        return false; // cache miss
+    }
+    if ( time() - $mtime  > CONFIG_DOZMOD_EXPIRE) {
+        return false;
+    } else {
+        return true;
+    }
+}
+
+
+function cache_get($key) {
+    $filename = cache_key_to_filename($key);
+    return file_get_contents($filename); 
+}
+
+/* good for large binary files */
+function cache_get_passthru($key) {
+    $filename = cache_key_to_filename($key);
+    $fp = fopen($filename, "r");
+    fpassthru($fp);
+}
+/* END: Cache ---------------------------------------------------- */
+
 
 /* this script requires 2 (3 with implicit client ip) parameters 
  *
@@ -18,9 +71,8 @@ function println($str) { echo "$str\n"; }
 
 /* return an array of lecutre uuids.
  * Parameter: an array with location Ids
- * Cacheable
  * */
-function getLecturesForLocations($locationIds) {
+function _getLecturesForLocations($locationIds) {
     $ids = implode('%20', $locationIds);
     $url = LIST_URL . "?locations=$ids";
     $responseXML = Download::asString($url, 60, $code);
@@ -32,13 +84,36 @@ function getLecturesForLocations($locationIds) {
     }
     return $uuids;
 } 
+/** Caching wrapper around _getLecturesForLocations() *//
+function getLecturesForLocations($locationIds) {
+    $key = 'lectures_' . cache_hash($locationIds);
+    if (cache_has($key)) {
+        return unserialize(cache_get($key));
+    } else {
+        $value = _getLecturesForLocations($locationIds);
+        cache_put($key, serialize($value));
+        return $value;
+    }
+}
 
-function getVMX($lecture_uuid) {
+function _getVMX($lecture_uuid) {
     $url = VMX_URL . '/' . $lecture_uuid;
     $response = Download::asString($url, 60, $code);
     return $response;
 }
 
+/** Caching wrapper around _getVMX() **/
+function getVMX($lecture_uuid) {
+    $key = 'vmx_' . $lecture_uuid;
+    if (cache_has($key)) {
+        cache_get_passthru($key);
+    } else {
+        $value = _getVMX($lecture_uuid);
+        cache_put($key, $value);
+        return $value;
+    }
+}
+
 
 // -----------------------------------------------------------------------------// 
 $ip = $_SERVER['REMOTE_ADDR'];
@@ -58,7 +133,6 @@ $location_ids = Location::getFromIP($request['ip']);
 /* lookup lecture uuids */
 $lectures = getLecturesForLocations(array($location_ids));
 
-
 /* validate request -------------------------------------------- */
 /* check ressources */
 if (!in_array($request['ressource'], $availableRessources)) {