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package main
import (
"fmt"
"io"
"os"
"time"
"github.com/pion/webrtc/v3"
"github.com/pion/webrtc/v3/examples/internal/signal"
)
const messageSize = 15
func main() {
// Since this behavior diverges from the WebRTC API it has to be
// enabled using a settings engine. Mixing both detached and the
// OnMessage DataChannel API is not supported.
// Create a SettingEngine and enable Detach
s := webrtc.SettingEngine{}
s.DetachDataChannels()
// Create an API object with the engine
api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
// Everything below is the Pion WebRTC API! Thanks for using it ❤️.
// Prepare the configuration
config := webrtc.Configuration{
ICEServers: []webrtc.ICEServer{
{
URLs: []string{"stun:stun.l.google.com:19302"},
},
},
}
// Create a new RTCPeerConnection using the API object
peerConnection, err := api.NewPeerConnection(config)
if err != nil {
panic(err)
}
defer func() {
if cErr := peerConnection.Close(); cErr != nil {
fmt.Printf("cannot close peerConnection: %v\n", cErr)
}
}()
// Set the handler for Peer connection state
// This will notify you when the peer has connected/disconnected
peerConnection.OnConnectionStateChange(func(s webrtc.PeerConnectionState) {
fmt.Printf("Peer Connection State has changed: %s\n", s.String())
if s == webrtc.PeerConnectionStateFailed {
// Wait until PeerConnection has had no network activity for 30 seconds or another failure. It may be reconnected using an ICE Restart.
// Use webrtc.PeerConnectionStateDisconnected if you are interested in detecting faster timeout.
// Note that the PeerConnection may come back from PeerConnectionStateDisconnected.
fmt.Println("Peer Connection has gone to failed exiting")
os.Exit(0)
}
})
// Register data channel creation handling
peerConnection.OnDataChannel(func(d *webrtc.DataChannel) {
fmt.Printf("New DataChannel %s %d\n", d.Label(), d.ID())
// Register channel opening handling
d.OnOpen(func() {
fmt.Printf("Data channel '%s'-'%d' open.\n", d.Label(), d.ID())
// Detach the data channel
raw, dErr := d.Detach()
if dErr != nil {
panic(dErr)
}
// Handle reading from the data channel
go ReadLoop(raw)
// Handle writing to the data channel
go WriteLoop(raw)
})
})
// Wait for the offer to be pasted
offer := webrtc.SessionDescription{}
signal.Decode(signal.MustReadStdin(), &offer)
// Set the remote SessionDescription
err = peerConnection.SetRemoteDescription(offer)
if err != nil {
panic(err)
}
// Create answer
answer, err := peerConnection.CreateAnswer(nil)
if err != nil {
panic(err)
}
// Create channel that is blocked until ICE Gathering is complete
gatherComplete := webrtc.GatheringCompletePromise(peerConnection)
// Sets the LocalDescription, and starts our UDP listeners
err = peerConnection.SetLocalDescription(answer)
if 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
// Output the answer in base64 so we can paste it in browser
fmt.Println(signal.Encode(*peerConnection.LocalDescription()))
// Block forever
select {}
}
// ReadLoop shows how to read from the datachannel directly
func ReadLoop(d io.Reader) {
for {
buffer := make([]byte, messageSize)
n, err := d.Read(buffer)
if err != nil {
fmt.Println("Datachannel closed; Exit the readloop:", err)
return
}
fmt.Printf("Message from DataChannel: %s\n", string(buffer[:n]))
}
}
// WriteLoop shows how to write to the datachannel directly
func WriteLoop(d io.Writer) {
for range time.NewTicker(5 * time.Second).C {
message := signal.RandSeq(messageSize)
fmt.Printf("Sending %s \n", message)
_, err := d.Write([]byte(message))
if err != nil {
panic(err)
}
}
}
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