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package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"net/http"
"os"
"sync"
"time"
"github.com/pion/webrtc/v3"
"github.com/pion/webrtc/v3/examples/internal/signal"
)
func signalCandidate(addr string, c *webrtc.ICECandidate) error {
payload := []byte(c.ToJSON().Candidate)
resp, err := http.Post(fmt.Sprintf("http://%s/candidate", addr), // nolint:noctx
"application/json; charset=utf-8", bytes.NewReader(payload))
if err != nil {
return err
}
if closeErr := resp.Body.Close(); closeErr != nil {
return closeErr
}
return nil
}
func main() { // nolint:gocognit
offerAddr := flag.String("offer-address", "localhost:50000", "Address that the Offer HTTP server is hosted on.")
answerAddr := flag.String("answer-address", ":60000", "Address that the Answer HTTP server is hosted on.")
flag.Parse()
var candidatesMux sync.Mutex
pendingCandidates := make([]*webrtc.ICECandidate, 0)
// 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
peerConnection, err := webrtc.NewPeerConnection(config)
if err != nil {
panic(err)
}
defer func() {
if err := peerConnection.Close(); err != nil {
fmt.Printf("cannot close peerConnection: %v\n", err)
}
}()
// When an ICE candidate is available send to the other Pion instance
// the other Pion instance will add this candidate by calling AddICECandidate
peerConnection.OnICECandidate(func(c *webrtc.ICECandidate) {
if c == nil {
return
}
candidatesMux.Lock()
defer candidatesMux.Unlock()
desc := peerConnection.RemoteDescription()
if desc == nil {
pendingCandidates = append(pendingCandidates, c)
} else if onICECandidateErr := signalCandidate(*offerAddr, c); onICECandidateErr != nil {
panic(onICECandidateErr)
}
})
// A HTTP handler that allows the other Pion instance to send us ICE candidates
// This allows us to add ICE candidates faster, we don't have to wait for STUN or TURN
// candidates which may be slower
http.HandleFunc("/candidate", func(w http.ResponseWriter, r *http.Request) {
candidate, candidateErr := ioutil.ReadAll(r.Body)
if candidateErr != nil {
panic(candidateErr)
}
if candidateErr := peerConnection.AddICECandidate(webrtc.ICECandidateInit{Candidate: string(candidate)}); candidateErr != nil {
panic(candidateErr)
}
})
// A HTTP handler that processes a SessionDescription given to us from the other Pion process
http.HandleFunc("/sdp", func(w http.ResponseWriter, r *http.Request) {
sdp := webrtc.SessionDescription{}
if err := json.NewDecoder(r.Body).Decode(&sdp); err != nil {
panic(err)
}
if err := peerConnection.SetRemoteDescription(sdp); err != nil {
panic(err)
}
// Create an answer to send to the other process
answer, err := peerConnection.CreateAnswer(nil)
if err != nil {
panic(err)
}
// Send our answer to the HTTP server listening in the other process
payload, err := json.Marshal(answer)
if err != nil {
panic(err)
}
resp, err := http.Post(fmt.Sprintf("http://%s/sdp", *offerAddr), "application/json; charset=utf-8", bytes.NewReader(payload)) // nolint:noctx
if err != nil {
panic(err)
} else if closeErr := resp.Body.Close(); closeErr != nil {
panic(closeErr)
}
// Sets the LocalDescription, and starts our UDP listeners
err = peerConnection.SetLocalDescription(answer)
if err != nil {
panic(err)
}
candidatesMux.Lock()
for _, c := range pendingCandidates {
onICECandidateErr := signalCandidate(*offerAddr, c)
if onICECandidateErr != nil {
panic(onICECandidateErr)
}
}
candidatesMux.Unlock()
})
// 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. Random messages will now be sent to any connected DataChannels every 5 seconds\n", d.Label(), d.ID())
for range time.NewTicker(5 * time.Second).C {
message := signal.RandSeq(15)
fmt.Printf("Sending '%s'\n", message)
// Send the message as text
sendTextErr := d.SendText(message)
if sendTextErr != nil {
panic(sendTextErr)
}
}
})
// Register text message handling
d.OnMessage(func(msg webrtc.DataChannelMessage) {
fmt.Printf("Message from DataChannel '%s': '%s'\n", d.Label(), string(msg.Data))
})
})
// Start HTTP server that accepts requests from the offer process to exchange SDP and Candidates
panic(http.ListenAndServe(*answerAddr, nil))
}
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