snapshot of https://github.com/pion/webrtc.git (main, 2026-09-15; blobs > 131072B omitted)

examples/trickle-ice/main.go

@@ -0,0 +1,146 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+// trickle-ice demonstrates Pion WebRTC's Trickle ICE APIs.  ICE is the subsystem WebRTC uses to establish connectivity.
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/pion/webrtc/v4"
+	"golang.org/x/net/websocket"
+)
+
+// websocketServer is called for every new inbound WebSocket
+// nolint: gocognit, cyclop
+func websocketServer(wsConn *websocket.Conn) {
+	// 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(candidate *webrtc.ICECandidate) {
+		if candidate == nil {
+			return
+		}
+
+		outbound, marshalErr := json.Marshal(candidate.ToJSON())
+		if marshalErr != nil {
+			fmt.Println("Marshal ICECandidate error:", marshalErr)
+
+			return
+		}
+
+		if _, err = wsConn.Write(outbound); err != nil {
+			fmt.Println("WebSocket write error:", err)
+
+			return
+		}
+	})
+
+	// 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() {
+			fmt.Println(time.Now().Format("15:04:05"), "- DataChannel open")
+			// Periodically send timestamped messages
+			go func() {
+				ticker := time.NewTicker(time.Second * 3)
+				defer ticker.Stop()
+				for range ticker.C {
+					if err := d.SendText(time.Now().String()); err != nil {
+						fmt.Println(time.Now().Format("15:04:05"), "- DataChannel closed, stopping send loop")
+
+						return
+					}
+				}
+			}()
+		})
+	})
+
+	buf := make([]byte, 1500)
+	for {
+		// Read each inbound WebSocket Message
+		n, err := wsConn.Read(buf)
+		if err != nil {
+			fmt.Println(time.Now().Format("15:04:05"), "- WebSocket read error:", err)
+
+			return
+		}
+
+		// 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 {
+				fmt.Println("SetRemoteDescription error:", err)
+
+				return
+			}
+
+			answer, answerErr := peerConnection.CreateAnswer(nil)
+			if answerErr != nil {
+				fmt.Println("CreateAnswer error:", err)
+
+				return
+			}
+
+			if err = peerConnection.SetLocalDescription(answer); err != nil {
+				fmt.Println("SetLocalDescription error:", err)
+
+				return
+			}
+
+			outbound, marshalErr := json.Marshal(answer)
+			if marshalErr != nil {
+				fmt.Println("Marshal answer error:", err)
+
+				return
+			}
+
+			if _, err = wsConn.Write(outbound); err != nil {
+				fmt.Println("WebSocket write error:", err)
+
+				return
+			}
+		// 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 {
+				fmt.Println("AddICECandidate error:", err)
+
+				return
+			}
+		default:
+			fmt.Println("Unknown WebSocket 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")
+	// nolint: gosec
+	panic(http.ListenAndServe(":8080", nil))
+}