From 09c5ba0d0620eb96f2b9edc3525dbaa349e3274e Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Thu, 16 Sep 2021 17:17:36 +0200
Subject: [PATCH] Protect against tracks without a stream.

---
 rtpconn/webclient.go | 2 +-
 static/protocol.js   | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/rtpconn/webclient.go b/rtpconn/webclient.go
index 7a6bc59..58ede34 100644
--- a/rtpconn/webclient.go
+++ b/rtpconn/webclient.go
@@ -368,7 +368,7 @@ func addDownTrackUnlocked(conn *rtpDownConnection, remoteTrack *rtpUpTrack) erro
 		id = remoteTrack.track.Kind().String()
 	}
 	msid := remoteTrack.track.StreamID()
-	if msid == "" {
+	if msid == "" || msid == "-" {
 		log.Println("Got track with empty msid")
 		msid = remoteTrack.conn.Label()
 	}
diff --git a/static/protocol.js b/static/protocol.js
index 54ca3fe..65e2fc5 100644
--- a/static/protocol.js
+++ b/static/protocol.js
@@ -677,6 +677,10 @@ ServerConnection.prototype.gotOffer = async function(id, label, source, username
         };
 
         c.pc.ontrack = function(e) {
+            if(e.streams.length < 1) {
+                console.error("Got track with no stream");
+                return;
+            }
             c.stream = e.streams[0];
             let changed = recomputeUserStreams(sc, source, c);
             if(c.ondowntrack) {