From 6a37033ca87615610a73461d2605756cb918bbee Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Tue, 11 Aug 2020 15:13:30 +0200
Subject: [PATCH] Allow both sides to initiate renegotiation.

More reliable reaction to network failures when they are detected
by just one side.
---
 static/sfu.js | 22 +++++++++++++++++++---
 webclient.go  | 38 ++++++++++++++++++++++++++++++--------
 2 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/static/sfu.js b/static/sfu.js
index a624faf..a3bd7ba 100644
--- a/static/sfu.js
+++ b/static/sfu.js
@@ -648,6 +648,17 @@ function serverConnect() {
             case 'answer':
                 gotAnswer(m.id, m.answer);
                 break;
+            case 'renegotiate':
+                let c = up[id];
+                if(c) {
+                    try {
+                        c.pc.restartIce()
+                    } catch(e) {
+                        console.error(e);
+                        displayError(e);
+                    }
+                }
+                break;
             case 'close':
                 gotClose(m.id);
                 break;
@@ -743,6 +754,11 @@ async function gotOffer(id, labels, offer, renegotiate) {
 
         pc.oniceconnectionstatechange = e => {
             setMediaStatus(id);
+            if(pc.iceConnectionState === 'failed') {
+                send({type: 'renegotiate',
+                      id: id,
+                     });
+            }
         }
 
         c.pc.ontrack = function(e) {
@@ -1179,7 +1195,7 @@ async function newUpStream(id) {
 
     pc.onnegotiationneeded = async e => {
         try {
-            await negotiate(id);
+            await negotiate(id, false);
         } catch(e) {
             console.error(e);
             displayError(e);
@@ -1213,7 +1229,7 @@ async function newUpStream(id) {
     return id;
 }
 
-async function negotiate(id) {
+async function negotiate(id, restartIce) {
     let c = up[id];
     if(!c)
         throw new Error('unknown connection');
@@ -1221,7 +1237,7 @@ async function negotiate(id) {
     if(typeof(c.pc.getTransceivers) !== 'function')
         throw new Error('Browser too old, please upgrade');
 
-    let offer = await c.pc.createOffer({});
+    let offer = await c.pc.createOffer({iceRestart: restartIce});
     if(!offer)
         throw(new Error("Didn't create offer"));
     await c.pc.setLocalDescription(offer);
diff --git a/webclient.go b/webclient.go
index 102cbd7..8e58036 100644
--- a/webclient.go
+++ b/webclient.go
@@ -236,6 +236,12 @@ func addUpConn(c *webClient, id string) (*rtpUpConnection, bool, error) {
 		sendICE(c, id, candidate)
 	})
 
+	conn.pc.OnICEConnectionStateChange(func(state webrtc.ICEConnectionState) {
+		if state == webrtc.ICEConnectionStateFailed {
+			c.action(connectionFailedAction{id: id})
+		}
+	})
+
 	return conn, true, nil
 }
 
@@ -772,14 +778,11 @@ func clientLoop(c *webClient, conn *websocket.Conn) error {
 					go a.c.pushConn(u.id, u, ts, u.label)
 				}
 			case connectionFailedAction:
-				down := getDownConn(c, a.id)
-				if down == nil {
-					log.Printf("Failed indication for " +
-						"unknown connection")
-					continue
-				}
-				err := negotiate(c, down, true, true)
-				if err != nil {
+				if down := getDownConn(c, a.id); down != nil {
+					err := negotiate(c, down, true, true)
+					if err == nil {
+						return err
+					}
 					tracks := make(
 						[]upTrack, len(down.tracks),
 					)
@@ -790,7 +793,16 @@ func clientLoop(c *webClient, conn *websocket.Conn) error {
 						down.remote.Id(), down.remote,
 						tracks, down.remote.Label(),
 					)
+				} else if up := getUpConn(c, a.id); up != nil {
+					c.write(clientMessage{
+						Type: "renegotiate",
+						Id:   a.id,
+					})
+				} else {
+					log.Printf("Attempting to renegotiate " +
+						"unknown connection")
 				}
+
 			case permissionsChangedAction:
 				c.write(clientMessage{
 					Type:        "permissions",
@@ -930,6 +942,16 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 		if err != nil {
 			return err
 		}
+	case "renegotiate":
+		down := getDownConn(c, m.Id)
+		if down != nil {
+			err := negotiate(c, down, true, true)
+			if err != nil {
+				return err
+			}
+		} else {
+			log.Printf("Trying to renegotiate unknown connection")
+		}
 	case "close":
 		found := delUpConn(c, m.Id)
 		if !found {