if we get re-invite with no SDP (looking at you, BT) just respond with current offer

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019 jambonz
+Copyright (c) 2021 Drachtio Communications Services, LLC
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

lib/call-session.js

@@ -13,8 +13,8 @@ const MS_TEAMS_SIP_ENDPOINT = 'sip.pstnhub.microsoft.com';
 const createBLegFromHeader = (req) => {
   const from = req.getParsedHeader('From');
   const uri = parseUri(from.uri);
-  if (uri && uri.user) return `sip:${uri.user}@localhost`;
-  return 'sip:anonymous@localhost';
+  if (uri && uri.user) return `<sip:${uri.user}@localhost>`;
+  return '<sip:anonymous@localhost>';
 };
 
 class CallSession extends Emitter {
@@ -301,6 +301,12 @@ class CallSession extends Emitter {
 
   async _onReinvite(dlg, req, res) {
     try {
+      /* check for re-invite with no SDP -- seen that from BT when they provide UUI info */
+      if (!req.body) {
+        this.logger.info('got a reINVITE with no SDP; just respond with our current offer');
+        res.send(200, {body: dlg.local.sdp});
+        return;
+      }
       const fromTag = dlg.type === 'uas' ? this.rtpEngineOpts.uas.tag : this.rtpEngineOpts.uac.tag;
       const toTag = dlg.type === 'uas' ? this.rtpEngineOpts.uac.tag : this.rtpEngineOpts.uas.tag;
       const offerMedia = dlg.type === 'uas' ? this.rtpEngineOpts.uac.mediaOpts : this.rtpEngineOpts.uas.mediaOpts;