Add trickling (part 1)

relay.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"sync"
 	"time"
 
 	"github.com/pion/rtcp"
@@ -186,6 +187,10 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 
 	log.Printf("Starting new call: %s", mainOffer.callHash)
 
+	// Ice candidates mutex
+	var candidatesMux sync.Mutex
+	pendingCandidates := make([]*webrtc.ICECandidate, 0)
+
 	// Since we are answering use PayloadTypes declared by offerer
 	mediaEngine := webrtc.MediaEngine{}
 	err := mediaEngine.PopulateFromSDP(mainOffer.sdp)
@@ -195,8 +200,13 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 		return
 	}
 
+	// Enable trickling
+	s := webrtc.SettingEngine{}
+	s.SetTrickle(true)
+
 	// Create the API object with the MediaEngine
-	api := webrtc.NewAPI(webrtc.WithMediaEngine(mediaEngine))
+	api := webrtc.NewAPI(webrtc.WithMediaEngine(mediaEngine),
+		webrtc.WithSettingEngine(s))
 
 	// Setup config
 	peerConnectionConfig := webrtc.Configuration{
@@ -214,6 +224,28 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 	// Close peer connection
 	defer mainPeerConnection.Close()
 
+	// Forward ice candidates
+	mainPeerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
+		if c == nil || r.closed {
+			return
+		}
+
+		// Lock the list of candidates
+		candidatesMux.Lock()
+		defer candidatesMux.Unlock()
+
+		desc := mainPeerConnection.RemoteDescription()
+
+		if desc == nil {
+			// Add the signal to the pending list
+			pendingCandidates = append(pendingCandidates, c)
+		} else {
+			// Send the signal directly
+			sendSignal(mainOffer.callHash, mainOffer.peerID, c.ToJSON())
+		}
+
+	})
+
 	// Allow us to receive 1 audio & 1 video track
 	if _, err = mainPeerConnection.AddTransceiverFromKind(webrtc.RTPCodecTypeVideo,
 		webrtc.RtpTransceiverInit{Direction: webrtc.RTPTransceiverDirectionRecvonly}); err != nil {
@@ -316,16 +348,19 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 		return
 	}
 
-	// Forward ice candidates
-	mainPeerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
-		if c != nil {
-			sendSignal(mainOffer.callHash, mainOffer.peerID, c.ToJSON())
-		}
-	})
-
 	// Send anwser
 	if !r.closed {
 		sendSignal(mainOffer.callHash, mainOffer.peerID, answer)
+
+		// Warning ! Do not put this outside a specific block
+		candidatesMux.Lock()
+
+		// Send pending ice candidates
+		for _, val := range pendingCandidates {
+			sendSignal(mainOffer.callHash, mainOffer.peerID, val)
+		}
+
+		candidatesMux.Unlock()
 	}
 
 	// Keep a list of active tracks
@@ -401,6 +436,7 @@ func newCall(mainOffer receivedSignal, r activeRelay) {
 			// Send ice candidates
 			newPeerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
 				if c != nil {
+					println("new ice candidate 2")
 					sendSignal(r.callHash, newMessage.peerID, c.ToJSON())
 				}
 			})