Add examples/trickle-ice

Resolves #2030

examples/trickle-ice/main.go

@@ -0,0 +1,114 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/pion/webrtc/v3"
+	"golang.org/x/net/websocket"
+)
+
+// websocketServer is called for every new inbound WebSocket
+func websocketServer(ws *websocket.Conn) { // nolint:gocognit
+	// Create a new RTCPeerConnection
+	peerConnection, err := webrtc.NewPeerConnection(webrtc.Configuration{})
+	if err != nil {
+		panic(err)
+	}
+
+	// When Pion gathers a new ICE Candidate send it to the client. This is how
+	// ice trickle is implemented. Everytime we have a new candidate available we send
+	// it as soon as it is ready. We don't wait to emit a Offer/Answer until they are
+	// all available
+	peerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
+		if c == nil {
+			return
+		}
+
+		outbound, marshalErr := json.Marshal(c.ToJSON())
+		if marshalErr != nil {
+			panic(marshalErr)
+		}
+
+		if _, err = ws.Write(outbound); err != nil {
+			panic(err)
+		}
+	})
+
+	// Set the handler for ICE connection state
+	// This will notify you when the peer has connected/disconnected
+	peerConnection.OnICEConnectionStateChange(func(connectionState webrtc.ICEConnectionState) {
+		fmt.Printf("ICE Connection State has changed: %s\n", connectionState.String())
+	})
+
+	// Send the current time via a DataChannel to the remote peer every 3 seconds
+	peerConnection.OnDataChannel(func(d *webrtc.DataChannel) {
+		d.OnOpen(func() {
+			for range time.Tick(time.Second * 3) {
+				if err = d.SendText(time.Now().String()); err != nil {
+					panic(err)
+				}
+			}
+		})
+	})
+
+	buf := make([]byte, 1500)
+	for {
+		// Read each inbound WebSocket Message
+		n, err := ws.Read(buf)
+		if err != nil {
+			panic(err)
+		}
+
+		// Unmarshal each inbound WebSocket message
+		var (
+			candidate webrtc.ICECandidateInit
+			offer     webrtc.SessionDescription
+		)
+
+		switch {
+		// Attempt to unmarshal as a SessionDescription. If the SDP field is empty
+		// assume it is not one.
+		case json.Unmarshal(buf[:n], &offer) == nil && offer.SDP != "":
+			if err = peerConnection.SetRemoteDescription(offer); err != nil {
+				panic(err)
+			}
+
+			answer, answerErr := peerConnection.CreateAnswer(nil)
+			if answerErr != nil {
+				panic(answerErr)
+			}
+
+			if err = peerConnection.SetLocalDescription(answer); err != nil {
+				panic(err)
+			}
+
+			outbound, marshalErr := json.Marshal(answer)
+			if marshalErr != nil {
+				panic(marshalErr)
+			}
+
+			if _, err = ws.Write(outbound); err != nil {
+				panic(err)
+			}
+		// Attempt to unmarshal as a ICECandidateInit. If the candidate field is empty
+		// assume it is not one.
+		case json.Unmarshal(buf[:n], &candidate) == nil && candidate.Candidate != "":
+			if err = peerConnection.AddICECandidate(candidate); err != nil {
+				panic(err)
+			}
+		default:
+			panic("Unknown message")
+		}
+	}
+}
+
+func main() {
+	http.Handle("/", http.FileServer(http.Dir(".")))
+	http.Handle("/websocket", websocket.Handler(websocketServer))
+
+	fmt.Println("Open http://localhost:8080 to access this demo")
+	panic(http.ListenAndServe(":8080", nil))
+}