From e06c9d8be5d2660b6ab6a9a2c1d3c2dac6b5f232 Mon Sep 17 00:00:00 2001
From: Pierre HUBERT <pierre.git@communiquons.org>
Date: Sun, 12 Apr 2020 15:18:42 +0200
Subject: [PATCH] Add trickling on server (part 2)

---
 relay.go | 42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/relay.go b/relay.go
index a2ce897..51c9f13 100644
--- a/relay.go
+++ b/relay.go
@@ -202,7 +202,7 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 
 	// Enable trickling
 	s := webrtc.SettingEngine{}
-	s.SetTrickle(true)
+	s.SetTrickle(false)
 
 	// Create the API object with the MediaEngine
 	api := webrtc.NewAPI(webrtc.WithMediaEngine(mediaEngine),
@@ -403,6 +403,10 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 				val.Close()
 			}
 
+			// Ice candidates mutex
+			var newCandidatesMux sync.Mutex
+			newPendingCandidates := make([]*webrtc.ICECandidate, 0)
+
 			// Create new peer connection
 			newPeerConnection, err := api.NewPeerConnection(peerConnectionConfig)
 			if err != nil {
@@ -411,6 +415,27 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 			}
 			clients[newMessage.peerID] = newPeerConnection
 
+			// Send ice candidates
+			newPeerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
+				if c == nil || r.closed {
+					return
+				}
+
+				newCandidatesMux.Lock()
+				defer newCandidatesMux.Unlock()
+
+				// Check if we have already determined remote descprition
+				desc := newPeerConnection.LocalDescription()
+				if desc == nil {
+					// Append signal to the queue
+					newPendingCandidates = append(newPendingCandidates, c)
+				} else {
+					// Send the signal immedialy
+					sendSignal(r.callHash, newMessage.peerID, c.ToJSON())
+				}
+
+			})
+
 			// Add tracks
 			for _, value := range localTracks {
 				_, err = newPeerConnection.AddTrack(value)
@@ -433,17 +458,16 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 				continue
 			}
 
-			// Send ice candidates
-			newPeerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
-				if c != nil {
-					println("new ice candidate 2")
-					sendSignal(r.callHash, newMessage.peerID, c.ToJSON())
-				}
-			})
-
 			// Send offer
 			sendSignal(r.callHash, newMessage.peerID, offer)
 
+			// Send pending ice candidates
+			newCandidatesMux.Lock()
+			for _, c := range newPendingCandidates {
+				sendSignal(r.callHash, newMessage.peerID, c.ToJSON())
+			}
+			newCandidatesMux.Unlock()
+
 		} else if newMessage.sigType == SDP {
 
 			// Got an answer from the client