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

examples/ice-proxy/offer.go

@@ -0,0 +1,99 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build !js
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/pion/webrtc/v4"
+)
+
+// nolint:cyclop
+func setupOfferingAgent() {
+	var settingEngine webrtc.SettingEngine
+	// Allow loopback candidates.
+	settingEngine.SetIncludeLoopbackCandidate(true)
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(settingEngine))
+
+	// Create a new RTCPeerConnection.
+	peerConnection, err := api.NewPeerConnection(webrtc.Configuration{})
+	if err != nil {
+		panic(err)
+	}
+
+	// Log peer connection and ICE connection state changes.
+	peerConnection.OnConnectionStateChange(func(pcs webrtc.PeerConnectionState) {
+		log.Printf("[Offerer] Peer Connection State has changed: %s", pcs.String())
+	})
+	peerConnection.OnICEConnectionStateChange(func(ics webrtc.ICEConnectionState) {
+		log.Printf("[Offerer] ICE Connection State has changed: %s", ics.String())
+	})
+
+	// Create a data channel for measuring round-trip time.
+	dc, err := peerConnection.CreateDataChannel("data-channel", nil)
+	if err != nil {
+		panic(err)
+	}
+	dc.OnOpen(func() {
+		// Send the current time every 3 seconds.
+		for range time.Tick(3 * time.Second) {
+			if sendErr := dc.SendText(time.Now().Format(time.RFC3339Nano)); sendErr != nil {
+				panic(sendErr)
+			}
+		}
+	})
+	dc.OnMessage(func(msg webrtc.DataChannelMessage) {
+		// Receive the echoed time from the remote agent and calculate the round-trip time.
+		sendTime, parseErr := time.Parse(time.RFC3339Nano, string(msg.Data))
+		if parseErr != nil {
+			panic(parseErr)
+		}
+		log.Printf("[Offerer] Data channel round-trip time: %s", time.Since(sendTime))
+	})
+
+	gatherComplete := webrtc.GatheringCompletePromise(peerConnection)
+
+	// Create an offer to send to the answering agent.
+	offer, err := peerConnection.CreateOffer(nil)
+	if err != nil {
+		panic(err)
+	}
+
+	if err = peerConnection.SetLocalDescription(offer); err != nil {
+		panic(err)
+	}
+
+	// Block until ICE Gathering is complete, disabling trickle ICE.
+	// We do this because we only can exchange one signaling message.
+	// In a production application you should exchange ICE Candidates via OnICECandidate.
+	<-gatherComplete
+
+	offerJSON, err := json.Marshal(*peerConnection.LocalDescription())
+	if err != nil {
+		panic(err)
+	}
+
+	// Send offer to the answering agent.
+	// nolint:noctx
+	resp, err := http.Post("http://localhost:8080/sdp", "application/json", bytes.NewBuffer(offerJSON))
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close() // nolint:errcheck
+
+	// Receive answer and set remote description.
+	var answer webrtc.SessionDescription
+	if err = json.NewDecoder(resp.Body).Decode(&answer); err != nil {
+		panic(err)
+	}
+	if err = peerConnection.SetRemoteDescription(answer); err != nil {
+		panic(err)
+	}
+}