From 81f41aca20e32be1c672bb625df85e8568222794 Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Sat, 24 Jun 2023 19:18:05 +0530
Subject: [PATCH] Full reconnect on publication mismatch on resume. (#1823)

* Full reconnect on publication mismatch on resume.

It is possible that publications mismatch on resume. An example sequence
- Client sends `AddTrack` for `trackA`
- Server never receives it due to signalling connection breakage.
- Client could do a resume (reconnect=1) noticing signalling connection
  breakage.
- Client's view thinks that `trackA` is known to server, but server does
  not know about it.
- A subsequence offer containing `trackA` triggers `trackInfo not
  available before track publish` and the track does not get published.

Detect the case of missing track and issue a full reconnect.

* UpdateSubscriptions from sync state a la cloud

* add missing shouldReconnect
---
 pkg/rtc/room.go | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/pkg/rtc/room.go b/pkg/rtc/room.go
index df9db3764..dcd5a6b1c 100644
--- a/pkg/rtc/room.go
+++ b/pkg/rtc/room.go
@@ -526,6 +526,46 @@ func (r *Room) UpdateSubscriptions(
 }
 
 func (r *Room) SyncState(participant types.LocalParticipant, state *livekit.SyncState) error {
+	pLogger := participant.GetLogger()
+	pLogger.Infow("setting sync state", "state", state)
+
+	shouldReconnect := false
+	pubTracks := state.GetPublishTracks()
+	existingPubTracks := participant.GetPublishedTracks()
+	for _, pubTrack := range pubTracks {
+		// client may not have sent TrackInfo for each published track
+		ti := pubTrack.Track
+		if ti == nil {
+			pLogger.Warnw("TrackInfo not sent during resume", nil)
+			shouldReconnect = true
+			break
+		}
+
+		found := false
+		for _, existingPubTrack := range existingPubTracks {
+			if existingPubTrack.ID() == livekit.TrackID(ti.Sid) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			pLogger.Warnw("unknown track during resume", nil, "trackID", ti.Sid)
+			shouldReconnect = true
+			break
+		}
+	}
+	if shouldReconnect {
+		pLogger.Warnw("unable to resume due to missing published tracks, starting full reconnect", nil)
+		participant.IssueFullReconnect(types.ParticipantCloseReasonPublicationError)
+		return nil
+	}
+
+	r.UpdateSubscriptions(
+		participant,
+		livekit.StringsAsTrackIDs(state.Subscription.TrackSids),
+		state.Subscription.ParticipantTracks,
+		state.Subscription.Subscribe,
+	)
 	return nil
 }