DataChannels: OpenChannel & OnOpen

- OpenChannel messages are now sent after SCTP is Established.
- The OnOpen handler tells the application when a channel has opened.

Relates to #159

examples/data-channels-create/main.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"encoding/base64"
 	"fmt"
+	"io"
 	"math/rand"
 	"os"
 	"time"
@@ -34,22 +35,25 @@ func main() {
 	// Set the handler for ICE connection state
 	// This will notify you when the peer has connected/disconnected
 	peerConnection.OnICEConnectionStateChange = func(connectionState ice.ConnectionState) {
-		fmt.Printf("Connection State has changed %s \n", connectionState.String())
+		fmt.Printf("ICE Connection State has changed: %s\n", connectionState.String())
+	}
 
-		// TODO: find the correct place for this
-		if connectionState == ice.ConnectionStateConnected {
-			time.AfterFunc(3*time.Second, func() {
-				fmt.Println("sending openchannel")
-				err := dataChannel.SendOpenChannelMessage()
-				if err != nil {
-					fmt.Println("faild to send openchannel", err)
-				}
-			})
+	dataChannel.Lock()
+
+	// Register channel opening handling
+	dataChannel.OnOpen = func() {
+		fmt.Printf("Data channel '%s'-'%d' open. Random messages will now be sent to any connected DataChannels every 5 seconds\n", dataChannel.Label, dataChannel.ID)
+		for {
+			time.Sleep(5 * time.Second)
+			message := randSeq(15)
+			fmt.Printf("Sending %s \n", message)
+
+			err := dataChannel.Send(datachannel.PayloadString{Data: []byte(message)})
+			check(err)
 		}
 	}
 
 	// Register the Onmessage to handle incoming messages
-	dataChannel.Lock()
 	dataChannel.Onmessage = func(payload datachannel.Payload) {
 		switch p := payload.(type) {
 		case *datachannel.PayloadString:
@@ -60,6 +64,7 @@ func main() {
 			fmt.Printf("Message '%s' from DataChannel '%s' no payload \n", p.PayloadType().String(), dataChannel.Label)
 		}
 	}
+
 	dataChannel.Unlock()
 
 	// Create an offer to send to the browser
@@ -69,7 +74,7 @@ func main() {
 	// Output the offer in base64 so we can paste it in browser
 	fmt.Println(base64.StdEncoding.EncodeToString([]byte(offer.Sdp)))
 
-	// Wait for the offer to be pasted
+	// Wait for the answer to be pasted
 	sd := mustReadStdin()
 
 	// Set the remote SessionDescription
@@ -82,16 +87,8 @@ func main() {
 	err = peerConnection.SetRemoteDescription(answer)
 	check(err)
 
-	// Send messages every 5 seconds
-	fmt.Println("Random messages will now be sent to any connected DataChannels every 5 seconds")
-	for {
-		time.Sleep(5 * time.Second)
-		message := randSeq(15)
-		fmt.Printf("Sending %s \n", message)
-
-		err := dataChannel.Send(datachannel.PayloadString{Data: []byte(message)})
-		check(err)
-	}
+	// Block forever
+	select {}
 }
 
 // randSeq is used to generate a random message
@@ -109,12 +106,15 @@ func randSeq(n int) string {
 func mustReadStdin() string {
 	reader := bufio.NewReader(os.Stdin)
 	rawSd, err := reader.ReadString('\n')
-	check(err)
+	if err != io.EOF {
+		check(err)
+	}
 
 	fmt.Println("")
-	sd, err := base64.StdEncoding.DecodeString(rawSd)
 
+	sd, err := base64.StdEncoding.DecodeString(rawSd)
 	check(err)
+
 	return string(sd)
 }
 

examples/data-channels/main.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"math/rand"
 	"os"
-	"sync"
 	"time"
 
 	"github.com/pions/webrtc"
@@ -15,61 +14,52 @@ import (
 	"github.com/pions/webrtc/pkg/ice"
 )
 
-func randSeq(n int) string {
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
-	b := make([]rune, n)
-	for i := range b {
-		b[i] = letters[r.Intn(len(letters))]
-	}
-	return string(b)
-}
-
 func main() {
-	reader := bufio.NewReader(os.Stdin)
-	rawSd, err := reader.ReadString('\n')
-	if err != nil && err != io.EOF {
-		panic(err)
-	}
-
-	fmt.Println("")
-	sd, err := base64.StdEncoding.DecodeString(rawSd)
-	if err != nil {
-		panic(err)
-	}
+	// Wait for the offer to be pasted
+	sd := mustReadStdin()
 
 	/* Everything below is the pion-WebRTC API, thanks for using it! */
 
-	// Create a new RTCPeerConnection
-	peerConnection, err := webrtc.New(webrtc.RTCConfiguration{
+	// Prepare the configuration
+	config := webrtc.RTCConfiguration{
 		IceServers: []webrtc.RTCIceServer{
 			{
 				URLs: []string{"stun:stun.l.google.com:19302"},
 			},
 		},
-	})
-	if err != nil {
-		panic(err)
 	}
 
+	// Create a new RTCPeerConnection
+	peerConnection, err := webrtc.New(config)
+	check(err)
+
 	// Set the handler for ICE connection state
 	// This will notify you when the peer has connected/disconnected
 	peerConnection.OnICEConnectionStateChange = func(connectionState ice.ConnectionState) {
-		fmt.Printf("Connection State has changed %s \n", connectionState.String())
+		fmt.Printf("ICE Connection State has changed: %s\n", connectionState.String())
 	}
 
-	datachannels := make([]*webrtc.RTCDataChannel, 0)
-	var dataChannelsLock sync.RWMutex
-
+	// Register data channel creation handling
 	peerConnection.OnDataChannel = func(d *webrtc.RTCDataChannel) {
-		dataChannelsLock.Lock()
-		datachannels = append(datachannels, d)
-		dataChannelsLock.Unlock()
-
 		fmt.Printf("New DataChannel %s %d\n", d.Label, d.ID)
 
 		d.Lock()
 		defer d.Unlock()
+
+		// Register channel opening handling
+		d.OnOpen = func() {
+			fmt.Printf("Data channel '%s'-'%d' open. Random messages will now be sent to any connected DataChannels every 5 seconds\n", d.Label, d.ID)
+			for {
+				time.Sleep(5 * time.Second)
+				message := randSeq(15)
+				fmt.Printf("Sending %s \n", message)
+
+				err := d.Send(datachannel.PayloadString{Data: []byte(message)})
+				check(err)
+			}
+		}
+
+		// Register message handling
 		d.Onmessage = func(payload datachannel.Payload) {
 			switch p := payload.(type) {
 			case *datachannel.PayloadString:
@@ -87,31 +77,50 @@ func main() {
 		Type: webrtc.RTCSdpTypeOffer,
 		Sdp:  string(sd),
 	}
-	if err := peerConnection.SetRemoteDescription(offer); err != nil {
-		panic(err)
-	}
+
+	err = peerConnection.SetRemoteDescription(offer)
+	check(err)
 
 	// Sets the LocalDescription, and starts our UDP listeners
 	answer, err := peerConnection.CreateAnswer(nil)
-	if err != nil {
-		panic(err)
-	}
+	check(err)
 
 	// Get the LocalDescription and take it to base64 so we can paste in browser
 	fmt.Println(base64.StdEncoding.EncodeToString([]byte(answer.Sdp)))
-	fmt.Println("Random messages will now be sent to any connected DataChannels every 5 seconds")
-	for {
-		time.Sleep(5 * time.Second)
-		message := randSeq(15)
-		fmt.Printf("Sending %s \n", message)
 
-		dataChannelsLock.RLock()
-		for _, d := range datachannels {
-			err := d.Send(datachannel.PayloadString{Data: []byte(message)})
-			if err != nil {
-				panic(err)
-			}
-		}
-		dataChannelsLock.RUnlock()
+	// Block forever
+	select {}
+}
+
+func randSeq(n int) string {
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+	b := make([]rune, n)
+	for i := range b {
+		b[i] = letters[r.Intn(len(letters))]
+	}
+	return string(b)
+}
+
+// mustReadStdin blocks untill input is received from stdin
+func mustReadStdin() string {
+	reader := bufio.NewReader(os.Stdin)
+	rawSd, err := reader.ReadString('\n')
+	if err != io.EOF {
+		check(err)
+	}
+
+	fmt.Println("")
+
+	sd, err := base64.StdEncoding.DecodeString(rawSd)
+	check(err)
+
+	return string(sd)
+}
+
+// check is used to panic in an error occurs.
+func check(err error) {
+	if err != nil {
+		panic(err)
 	}
 }

examples/pion-to-pion/answer/main.go

@@ -45,13 +45,6 @@ func buildPeerConnection() *webrtc.RTCPeerConnection {
 
 	peerConnection.OnICEConnectionStateChange = func(connectionState ice.ConnectionState) {
 		fmt.Printf("Connection State has changed %s \n", connectionState.String())
-		if connectionState == ice.ConnectionStateConnected {
-			fmt.Println("sending openchannel")
-			err := d.SendOpenChannelMessage()
-			if err != nil {
-				fmt.Println("faild to send openchannel", err)
-			}
-		}
 	}
 
 	return peerConnection

internal/network/manager.go

@@ -59,7 +59,7 @@ func NewManager(btg BufferTransportGenerator, dcet DataChannelEventHandler, ntf
 		return nil, err
 	}
 
-	m.sctpAssociation = sctp.NewAssocation(m.dataChannelOutboundHandler, m.dataChannelInboundHandler, nil)
+	m.sctpAssociation = sctp.NewAssocation(m.dataChannelOutboundHandler, m.dataChannelInboundHandler, m.handleSCTPState)
 
 	m.IceAgent = ice.NewAgent(m.iceOutboundHandler, m.iceNotifier)
 	for _, i := range localInterfaces() {
@@ -87,6 +87,13 @@ func (m *Manager) handleDTLSState(state dtls.ConnectionState) {
 	}
 }
 
+func (m *Manager) handleSCTPState(state sctp.AssociationState) {
+	if state == sctp.Established {
+		// Temporary way to signal sending OpenChannel messages
+		m.dataChannelEventHandler(&DataChannelOpen{})
+	}
+}
+
 // AddURL takes an ICE Url, allocates any state and adds the candidate
 func (m *Manager) AddURL(url *ice.URL) error {
 

internal/network/network.go

@@ -51,3 +51,11 @@ type DataChannelMessage struct {
 func (d *DataChannelMessage) StreamIdentifier() uint16 {
 	return d.streamIdentifier
 }
+
+// DataChannelOpen is emitted when all channels should be opened
+type DataChannelOpen struct{}
+
+// StreamIdentifier returns the streamIdentifier
+func (d *DataChannelOpen) StreamIdentifier() uint16 {
+	return 0
+}

rtcdatachannel.go

@@ -99,6 +99,10 @@ type RTCDataChannel struct {
 	// arrival over the sctp transport from a remote peer.
 	OnMessage func(datachannel.Payload)
 
+	// OnOpen designates an event handler which is invoked when
+	// the underlying data transport has been established (or re-established).
+	OnOpen func()
+
 	// Deprecated: Will be removed when networkManager is deprecated.
 	rtcPeerConnection *RTCPeerConnection
 }
@@ -122,8 +126,7 @@ type RTCDataChannel struct {
 // 	return &rtcerr.OperationError{Err: ErrMaxDataChannelID}
 // }
 
-// SendOpenChannelMessage is a test to send OpenChannel manually
-func (d *RTCDataChannel) SendOpenChannelMessage() error {
+func (d *RTCDataChannel) sendOpenChannelMessage() error {
 	if err := d.rtcPeerConnection.networkManager.SendOpenChannelMessage(*d.ID, d.Label); err != nil {
 		return &rtcerr.UnknownError{Err: err}
 	}
@@ -138,3 +141,12 @@ func (d *RTCDataChannel) Send(p datachannel.Payload) error {
 	}
 	return nil
 }
+
+func (d *RTCDataChannel) doOnOpen() {
+	d.RLock()
+	onOpen := d.OnOpen
+	d.RUnlock()
+	if onOpen != nil {
+		onOpen()
+	}
+}

rtcpeerconnection.go

@@ -809,10 +809,15 @@ func (pc *RTCPeerConnection) dataChannelEventHandler(e network.DataChannelEvent)
 	switch event := e.(type) {
 	case *network.DataChannelCreated:
 		id := event.StreamIdentifier()
-		newDataChannel := &RTCDataChannel{ID: &id, Label: event.Label, rtcPeerConnection: pc}
+		newDataChannel := &RTCDataChannel{ID: &id, Label: event.Label, rtcPeerConnection: pc, ReadyState: RTCDataChannelStateOpen}
 		pc.dataChannels[e.StreamIdentifier()] = newDataChannel
 		if pc.OnDataChannel != nil {
-			go pc.OnDataChannel(newDataChannel)
+			go func() {
+				pc.OnDataChannel(newDataChannel) // This should actually be called when processing the SDP answer.
+				if newDataChannel.OnOpen != nil {
+					go newDataChannel.doOnOpen()
+				}
+			}()
 		} else {
 			fmt.Println("OnDataChannel is unset, discarding message")
 		}
@@ -830,6 +835,20 @@ func (pc *RTCPeerConnection) dataChannelEventHandler(e network.DataChannelEvent)
 			fmt.Printf("No datachannel found for streamIdentifier %d \n", e.StreamIdentifier())
 
 		}
+	case *network.DataChannelOpen:
+		for _, dc := range pc.dataChannels {
+			dc.Lock()
+			err := dc.sendOpenChannelMessage()
+			if err != nil {
+				fmt.Println("failed to send openchannel", err)
+				dc.Unlock()
+				continue
+			}
+			dc.ReadyState = RTCDataChannelStateOpen
+			dc.Unlock()
+
+			go dc.doOnOpen() // TODO: move to ChannelAck handling
+		}
 	default:
 		fmt.Printf("Unhandled DataChannelEvent %v \n", event)
 	}