Add group permissions.

static/sfu.html

@@ -29,9 +29,9 @@
 
       <div id="optionsdiv">
         <label for="presenterbox">Present:</label>
-        <input id="presenterbox" type="checkbox"/>
+        <input id="presenterbox" type="checkbox"/ disabled>
         <label for="sharebox">Share screen:</label>
-        <input id="sharebox" type="checkbox"/>
+        <input id="sharebox" type="checkbox"/ disabled>
       </div>
     </div>
 

static/sfu.js

@@ -279,8 +279,10 @@ function serverConnect() {
         socket.onclose = function(e) {
             setConnected(false);
             document.getElementById('presenterbox').checked = false;
+            document.getElementById('presenterbox').disabled = true;
             setLocalMedia();
             document.getElementById('sharebox').checked = false;
+            document.getElementById('sharebox').disabled = true;
             setShareMedia();
             reject(new Error('websocket close ' + e.code + ' ' + e.reason));
         };
@@ -305,6 +307,9 @@ function serverConnect() {
             case 'label':
                 gotLabel(m.id, m.value);
                 break;
+            case 'permissions':
+                gotPermissions(m.permissions);
+                break;
             case 'user':
                 gotUser(m.id, m.username, m.del);
                 break;
@@ -483,6 +488,11 @@ function gotUser(id, name, del) {
         addUser(id, name);
 }
 
+function gotPermissions(permissions) {
+    document.getElementById('presenterbox').disabled = !permissions.present;
+    document.getElementById('sharebox').disabled = !permissions.present;
+}
+
 const urlRegexp = /https?:\/\/[-a-zA-Z0-9@:%/._\+~#=?]+[-a-zA-Z0-9@:%/_\+~#=]/g;
 
 function formatLine(line) {