From eecddbb65a0c7d845d6488487b77c7e5524e9dfc Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Mon, 31 Jul 2023 11:43:47 +0530
Subject: [PATCH] Issue full reconnect if subscriber PC is closed on ICERestart
 (#1919)

Server could have closed subscriber PC to aid migration.
But, if a resumes lands back on that node, a resume of
the participant session is not possible as subscriber PC is already
closed. While theoretically possible to form a new subscriber
peer conenction, reducing complexity and issuing a full reconnect
as this should be a rare case.
---
 pkg/rtc/participant.go      |  4 +++-
 pkg/rtc/transport.go        | 23 +++++++++++++++--------
 pkg/rtc/transportmanager.go |  4 ++--
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/pkg/rtc/participant.go b/pkg/rtc/participant.go
index aea4c9e94..cd0d61e9d 100644
--- a/pkg/rtc/participant.go
+++ b/pkg/rtc/participant.go
@@ -863,7 +863,9 @@ func (p *ParticipantImpl) ICERestart(iceConfig *livekit.ICEConfig) {
 		t.(types.LocalMediaTrack).Restart()
 	}
 
-	p.TransportManager.ICERestart(iceConfig)
+	if err := p.TransportManager.ICERestart(iceConfig); err != nil {
+		p.IssueFullReconnect(types.ParticipantCloseReasonNegotiateFailed)
+	}
 }
 
 func (p *ParticipantImpl) OnICEConfigChanged(f func(participant types.LocalParticipant, iceConfig *livekit.ICEConfig)) {
diff --git a/pkg/rtc/transport.go b/pkg/rtc/transport.go
index 0eaabd1ed..2c565f194 100644
--- a/pkg/rtc/transport.go
+++ b/pkg/rtc/transport.go
@@ -72,13 +72,14 @@ const (
 )
 
 var (
-	ErrIceRestartWithoutLocalSDP = errors.New("ICE restart without local SDP settled")
-	ErrNoTransceiver             = errors.New("no transceiver")
-	ErrNoSender                  = errors.New("no sender")
-	ErrNoICECandidateHandler     = errors.New("no ICE candidate handler")
-	ErrNoOfferHandler            = errors.New("no offer handler")
-	ErrNoAnswerHandler           = errors.New("no answer handler")
-	ErrMidNotFound               = errors.New("mid not found")
+	ErrIceRestartWithoutLocalSDP        = errors.New("ICE restart without local SDP settled")
+	ErrIceRestartOnClosedPeerConnection = errors.New("ICE restart on closed peer connection")
+	ErrNoTransceiver                    = errors.New("no transceiver")
+	ErrNoSender                         = errors.New("no sender")
+	ErrNoICECandidateHandler            = errors.New("no ICE candidate handler")
+	ErrNoOfferHandler                   = errors.New("no offer handler")
+	ErrNoAnswerHandler                  = errors.New("no answer handler")
+	ErrMidNotFound                      = errors.New("mid not found")
 )
 
 // -------------------------------------------------------------------------
@@ -1103,10 +1104,16 @@ func (t *PCTransport) Negotiate(force bool) {
 	}
 }
 
-func (t *PCTransport) ICERestart() {
+func (t *PCTransport) ICERestart() error {
+	if t.pc.ConnectionState() == webrtc.PeerConnectionStateClosed {
+		t.params.Logger.Warnw("trying to restart ICE on closed peer connection", nil)
+		return ErrIceRestartOnClosedPeerConnection
+	}
+
 	t.postEvent(event{
 		signal: signalICERestart,
 	})
+	return nil
 }
 
 func (t *PCTransport) ResetShortConnOnICERestart() {
diff --git a/pkg/rtc/transportmanager.go b/pkg/rtc/transportmanager.go
index 3f698ebe1..1b056b6e4 100644
--- a/pkg/rtc/transportmanager.go
+++ b/pkg/rtc/transportmanager.go
@@ -521,12 +521,12 @@ func (t *TransportManager) HandleClientReconnect(reason livekit.ReconnectReason)
 	}
 }
 
-func (t *TransportManager) ICERestart(iceConfig *livekit.ICEConfig) {
+func (t *TransportManager) ICERestart(iceConfig *livekit.ICEConfig) error {
 	if iceConfig != nil {
 		t.SetICEConfig(iceConfig)
 	}
 
-	t.subscriber.ICERestart()
+	return t.subscriber.ICERestart()
 }
 
 func (t *TransportManager) OnICEConfigChanged(f func(iceConfig *livekit.ICEConfig)) {