mirror of
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118 lines
3.3 KiB
Go
118 lines
3.3 KiB
Go
// SPDX-FileCopyrightText: 2025 The Pion community <https://pion.ly>
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// SPDX-License-Identifier: MIT
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//go:build !js
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// +build !js
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package main
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import (
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"encoding/json"
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"log"
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"net/http"
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"github.com/pion/webrtc/v4"
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)
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// nolint:cyclop
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func setupAnsweringAgent() {
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// Create and start a simple HTTP proxy server.
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proxyURL := newHTTPProxy()
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// Create a proxy dialer that will use the created HTTP proxy.
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proxyDialer := newProxyDialer(proxyURL)
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var settingEngine webrtc.SettingEngine
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// Set the ICEProxyDialer to use the proxy for TURN+TCP connections.
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settingEngine.SetICEProxyDialer(proxyDialer)
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api := webrtc.NewAPI(webrtc.WithSettingEngine(settingEngine))
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peerConnection, err := api.NewPeerConnection(webrtc.Configuration{
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ICEServers: []webrtc.ICEServer{
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{
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URLs: []string{turnServerURL},
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Username: turnUsername,
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Credential: turnPassword,
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},
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},
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// ICETransportPolicyRelay forces the connection to go through a TURN server.
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// This is required for the proxy to be used.
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ICETransportPolicy: webrtc.ICETransportPolicyRelay,
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})
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if err != nil {
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panic(err)
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}
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// Log peer connection and ICE connection state changes.
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peerConnection.OnConnectionStateChange(func(pcs webrtc.PeerConnectionState) {
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log.Printf("[Answerer] Peer Connection State has changed: %s", pcs.String())
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})
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peerConnection.OnICEConnectionStateChange(func(ics webrtc.ICEConnectionState) {
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log.Printf("[Answerer] ICE Connection State has changed: %s", ics.String())
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})
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// Register a handler for when a data channel is created by the remote peer.
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peerConnection.OnDataChannel(func(d *webrtc.DataChannel) {
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icePair, err := d.Transport().Transport().ICETransport().GetSelectedCandidatePair()
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if err != nil {
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panic(err)
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}
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// Log the chosen ICE candidate pair.
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log.Printf("[Answerer] New DataChannel %s, ICE pair: (%s)<->(%s)",
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d.Label(), icePair.Local.String(), icePair.Remote.String())
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// Register a handler to echo messages back to the sender.
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d.OnMessage(func(msg webrtc.DataChannelMessage) {
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if err := d.SendText(string(msg.Data)); err != nil {
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panic(err)
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}
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})
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})
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// HTTP handler that accepts an offer, creates an answer,
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// and sends it back to the offering agent.
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http.HandleFunc("/sdp", func(rw http.ResponseWriter, r *http.Request) {
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var sdp webrtc.SessionDescription
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if err := json.NewDecoder(r.Body).Decode(&sdp); err != nil {
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panic(err)
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}
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if err := peerConnection.SetRemoteDescription(sdp); err != nil {
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panic(err)
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}
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gatherComplete := webrtc.GatheringCompletePromise(peerConnection)
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answer, err := peerConnection.CreateAnswer(nil)
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if err != nil {
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panic(err)
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}
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if err = peerConnection.SetLocalDescription(answer); err != nil {
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panic(err)
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}
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// Block until ICE Gathering is complete, disabling trickle ICE
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// we do this because we only can exchange one signaling message
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// in a production application you should exchange ICE Candidates via OnICECandidate
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<-gatherComplete
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resp, err := json.Marshal(*peerConnection.LocalDescription())
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if err != nil {
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panic(err)
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}
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if _, err := rw.Write(resp); err != nil {
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panic(err)
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}
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})
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// Start an HTTP server to handle the SDP exchange from the offering agent.
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go func() {
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// The HTTP server is not gracefully shutdown in this example.
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// nolint:gosec
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err := http.ListenAndServe("localhost:8080", nil)
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if err != nil {
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panic(err)
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}
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}()
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}
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