Update check supports HTTPS

If SSL is not supported, a HTTP request will be made. In the log the request type will be indicated, but on the frontend no additional message would be shown (I think it's better to notify admins about non-SSL situations, but currently when this fetch encounter error, no error message will be shown, so it's better not to add any warning).

inc/infoutils.php

@@ -6,7 +6,14 @@
  * @author     Andreas Gohr <andi@splitbrain.org>
  */
 if(!defined('DOKU_INC')) die('meh.');
-if(!defined('DOKU_MESSAGEURL')) define('DOKU_MESSAGEURL','http://update.dokuwiki.org/check/');
+
+if(!defined('DOKU_MESSAGEURL')){
+    if(in_array('ssl', stream_get_transports())) {
+        define('DOKU_MESSAGEURL','https://update.dokuwiki.org/check/');
+    }else{
+        define('DOKU_MESSAGEURL','http://update.dokuwiki.org/check/');
+    }
+}
 
 /**
  * Check for new messages from upstream
@@ -22,11 +29,12 @@ function checkUpdateMessages(){
 
     $cf = getCacheName($updateVersion, '.updmsg');
     $lm = @filemtime($cf);
+    $is_http = substr(DOKU_MESSAGEURL, 0, 5) != 'https';
 
     // check if new messages needs to be fetched
     if($lm < time()-(60*60*24) || $lm < @filemtime(DOKU_INC.DOKU_SCRIPT)){
         @touch($cf);
-        dbglog("checkUpdateMessages(): downloading messages to ".$cf);
+        dbglog("checkUpdateMessages(): downloading messages to ".$cf.($is_http?' (without SSL)':' (with SSL)'));
         $http = new DokuHTTPClient();
         $http->timeout = 12;
         $resp = $http->get(DOKU_MESSAGEURL.$updateVersion);