add socketTransportProtocols parameter

settings.json.template

@@ -29,6 +29,13 @@
 
   */
 
+  // restricts socket.io transport methods to JSONP-POLLING only
+  // which is needed for IE8 browsers with deactivated native XMLHTTP support
+  // see issue https://github.com/ether/etherpad-lite/pull/958
+  // and https://github.com/ether/etherpad-lite/issues/245#issuecomment-4013455
+
+  "socketTransportProtocols" : ['xhr-polling', 'jsonp-polling', 'htmlfile'],
+  
   //The Type of the database. You can choose between dirty, postgres, sqlite and mysql
   //You shouldn't use "dirty" for for anything else than testing or development
   "dbType" : "dirty",

src/node/hooks/express/socketio.js

@@ -36,10 +36,10 @@ exports.expressCreateServer = function (hook_name, args, cb) {
     });
   });
 
-  // there shouldn#t be a browser that isn't compatible to all 
+  // there shouldn't be a browser that isn't compatible to all 
   // transports in this list at once
   // e.g. XHR is disabled in IE by default, so in IE it should use jsonp-polling
-  io.set('transports', ['xhr-polling', 'jsonp-polling', 'htmlfile']);
+  io.set('transports', settings.socketTransportProtocols );
 
   var socketIOLogger = log4js.getLogger("socket.io");
   io.set('logger', {

src/node/utils/Settings.js

@@ -57,6 +57,14 @@ exports.port = process.env.PORT || 9001;
  */
 exports.ssl = false;
 
+/**
+ * restricts socket.io transport methods to JSONP-POLLING only
+ * which is needed for IE8 browsers with deactivated native XMLHTTP support
+ * see issue https://github.com/ether/etherpad-lite/pull/958
+ * and https://github.com/ether/etherpad-lite/issues/245#issuecomment-4013455
+ **/
+exports.socketTransportProtocols = ['xhr-polling', 'jsonp-polling', 'htmlfile'];
+
 /*
  * The Type of the database
  */