Don't start TURN server by default if ice-servers.json exists.

This can be overridden by explicitly specifying the -turn option.

galene.go

@@ -44,9 +44,15 @@ func main() {
 	flag.BoolVar(&ice.ICERelayOnly, "relay-only", false,
 		"require use of TURN relays for all media traffic")
 	flag.StringVar(&turnserver.Address, "turn", ":1194",
-		"built-in TURN server address (\"\" to disable)")
+		"built-in TURN server `address` (\"\" to disable)")
 	flag.Parse()
 
+	flag.Visit(func(f *flag.Flag) {
+		if f.Name == "turn" {
+			turnserver.Force = true
+		}
+	})
+
 	if cpuprofile != "" {
 		f, err := os.Create(cpuprofile)
 		if err != nil {
@@ -89,10 +95,8 @@ func main() {
 
 	go group.ReadPublicGroups()
 
-	err := turnserver.Start()
-	if err != nil {
-		log.Printf("TURN: %v", err)
-	}
+	// causes the built-in server to start if required
+	ice.Update()
 	defer turnserver.Stop()
 
 	serverDone := make(chan struct{})

ice/ice.go

@@ -74,15 +74,19 @@ type configuration struct {
 
 var conf atomic.Value
 
-func updateICEConfiguration() *configuration {
+func Update() *configuration {
 	now := time.Now()
 	var cf webrtc.Configuration
 
+	found := false
 	if ICEFilename != "" {
+		found = true
 		file, err := os.Open(ICEFilename)
 		if err != nil {
 			if !os.IsNotExist(err) {
 				log.Printf("Open %v: %v", ICEFilename, err)
+			} else {
+				found = false
 			}
 		} else {
 			defer file.Close()
@@ -103,6 +107,11 @@ func updateICEConfiguration() *configuration {
 		}
 	}
 
+	err := turnserver.StartStop(found)
+	if err != nil {
+		log.Printf("TURN: %v", err)
+	}
+
 	cf.ICEServers = append(cf.ICEServers, turnserver.ICEServers()...)
 
 	if ICERelayOnly {
@@ -120,9 +129,9 @@ func updateICEConfiguration() *configuration {
 func ICEConfiguration() *webrtc.Configuration {
 	conf, ok := conf.Load().(*configuration)
 	if !ok || time.Since(conf.timestamp) > 5*time.Minute {
-		conf = updateICEConfiguration()
+		conf = Update()
 	} else if time.Since(conf.timestamp) > 2*time.Minute {
-		go updateICEConfiguration()
+		go Update()
 	}
 
 	return &conf.conf

turnserver/turnserver.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"net"
 	"strconv"
+	"sync"
 
 	"github.com/pion/turn/v2"
 	"github.com/pion/webrtc/v3"
@@ -14,9 +15,12 @@ import (
 
 var username string
 var password string
-var server *turn.Server
 var Address string
+var Force bool
+
+var mu sync.Mutex
 var addresses []net.Addr
+var server *turn.Server
 
 func publicAddresses() ([]net.IP, error) {
 	addrs, err := net.InterfaceAddrs()
@@ -82,8 +86,11 @@ func listener(a net.IP, port int, relay net.IP) (*turn.PacketConnConfig, *turn.L
 }
 
 func Start() error {
+	mu.Lock()
+	defer mu.Unlock()
+
 	if server != nil {
-		return errors.New("TURN server already started")
+		return nil
 	}
 
 	if Address == "" {
@@ -94,6 +101,8 @@ func Start() error {
 		return err
 	}
 
+	log.Printf("Starting built-in TURN server")
+
 	username = "galene"
 	buf := make([]byte, 6)
 	_, err = rand.Read(buf)
@@ -182,6 +191,9 @@ func Start() error {
 }
 
 func ICEServers() []webrtc.ICEServer {
+	mu.Lock()
+	defer mu.Unlock()
+
 	if len(addresses) == 0 {
 		return nil
 	}
@@ -208,12 +220,27 @@ func ICEServers() []webrtc.ICEServer {
 
 }
 
-func Stop() {
+func Stop() error {
+	mu.Lock()
+	defer mu.Unlock()
+
 	addresses = nil
 	if server == nil {
-		return
+		return nil
 	}
-	server.Close()
+	log.Printf("Stopping built-in TURN server")
+	err := server.Close()
 	server = nil
-	return
+	return err
+}
+
+func StartStop(found bool) error {
+	if Force && Address != "" {
+		return Start()
+	} else if found {
+		return Stop()
+	} else if Address != "" {
+		return Start()
+	}
+	return nil
 }