From 25ce8ef6661155231edaa17d5f1a132e7df29321 Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Thu, 14 Jan 2021 01:47:56 +0100
Subject: [PATCH] Implement server-side relay test.

---
 galene.go  | 18 +++++++++++
 ice/ice.go | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)

diff --git a/galene.go b/galene.go
index 5e18cd5..c4a1e12 100644
--- a/galene.go
+++ b/galene.go
@@ -98,13 +98,20 @@ func main() {
 	terminate := make(chan os.Signal, 1)
 	signal.Notify(terminate, syscall.SIGINT, syscall.SIGTERM)
 
+	go relayTest()
+
 	ticker := time.NewTicker(15 * time.Minute)
 	defer ticker.Stop()
 
+	slowTicker := time.NewTicker(12 * time.Hour)
+	defer slowTicker.Stop()
+
 	for {
 		select {
 		case <-ticker.C:
 			go group.Expire()
+		case <-slowTicker.C:
+			go relayTest()
 		case <-terminate:
 			webserver.Shutdown()
 			return
@@ -113,3 +120,14 @@ func main() {
 		}
 	}
 }
+
+func relayTest() {
+	now := time.Now()
+	d, err := ice.RelayTest()
+	if err != nil {
+		log.Printf("Relay test failed: %v", err)
+		log.Printf("Perhaps you didn't configure a TURN server?")
+		return
+	}
+	log.Printf("Relay test successful in %v, RTT = %v", time.Since(now), d)
+}
diff --git a/ice/ice.go b/ice/ice.go
index 5e07e9f..82953b6 100644
--- a/ice/ice.go
+++ b/ice/ice.go
@@ -123,3 +123,98 @@ func ICEConfiguration() *webrtc.Configuration {
 
 	return &conf.conf
 }
+
+func RelayTest() (time.Duration, error) {
+	conf := ICEConfiguration()
+	conf2 := *conf
+	conf2.ICETransportPolicy = webrtc.ICETransportPolicyRelay
+	pc1, err := webrtc.NewPeerConnection(conf2)
+	if err != nil {
+		return 0, err
+	}
+	defer pc1.Close()
+	pc2, err := webrtc.NewPeerConnection(*conf)
+	if err != nil {
+		return 0, err
+	}
+	defer pc2.Close()
+
+	pc1.OnICECandidate(func(c *webrtc.ICECandidate) {
+		if c != nil {
+			pc2.AddICECandidate(c.ToJSON())
+		}
+	})
+	pc2.OnICECandidate(func(c *webrtc.ICECandidate) {
+		if c != nil {
+			pc1.AddICECandidate(c.ToJSON())
+		}
+	})
+
+	d1, err := pc1.CreateDataChannel("loopback", nil)
+	if err != nil {
+		return 0, err
+	}
+
+	ch1 := make(chan error, 1)
+	d1.OnOpen(func() {
+		err := d1.Send([]byte(time.Now().Format(time.RFC3339Nano)))
+		if err != nil {
+			select {
+			case ch1 <- err:
+			default:
+			}
+		}
+	})
+
+	offer, err := pc1.CreateOffer(nil)
+	if err != nil {
+		return 0, err
+	}
+	err = pc1.SetLocalDescription(offer)
+	if err != nil {
+		return 0, err
+	}
+	err = pc2.SetRemoteDescription(*pc1.LocalDescription())
+	if err != nil {
+		return 0, err
+	}
+	answer, err := pc2.CreateAnswer(nil)
+	if err != nil {
+		return 0, err
+	}
+	err = pc2.SetLocalDescription(answer)
+	if err != nil {
+		return 0, err
+	}
+	err = pc1.SetRemoteDescription(*pc2.LocalDescription())
+	if err != nil {
+		return 0, err
+	}
+
+	ch2 := make(chan string, 1)
+	pc2.OnDataChannel(func(d2 *webrtc.DataChannel) {
+		d2.OnMessage(func(msg webrtc.DataChannelMessage) {
+			select {
+			case ch2 <- string(msg.Data):
+			default:
+			}
+		})
+	})
+
+	timer := time.NewTimer(20 * time.Second)
+	defer timer.Stop()
+	select {
+	case err := <-ch1:
+		return 0, err
+	case msg := <-ch2:
+		tm, err := time.Parse(time.RFC3339Nano, msg)
+		if err != nil {
+			return 0, err
+		}
+		log.Println(tm)
+		log.Println(time.Now())
+		return time.Now().Sub(tm), nil
+	case <-timer.C:
+		return 0, errors.New("timeout")
+	}
+}