mirror of
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git
synced 2025-10-13 20:11:19 -04:00
Refactor signal receiving in server.
There's one FIFO reader goroutine instead of one per bindaddr. makePeerConnectionFromOffer gives you a PeerConnection with an answer and also sets up callbacks to pass a webRTCConn to datachannelHandler when ready.
This commit is contained in:
David Fifield
parent
a77ae6b771
commit
ac8669b38f
1 changed files with 101 additions and 99 deletions
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@ -81,6 +81,8 @@ func (c *webRTCConn) SetWriteDeadline(t time.Time) error {
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}
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func datachannelHandler(conn *webRTCConn) {
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defer conn.Close()
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handlerChan <- 1
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defer func() {
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handlerChan <- -1
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@ -91,12 +93,34 @@ func datachannelHandler(conn *webRTCConn) {
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log.Printf("Failed to connect to ORPort: " + err.Error())
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return
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}
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//defer or.Close()
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defer or.Close()
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copyLoop(conn, or)
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}
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// Create a PeerConnection from an SDP offer. Blocks until the gathering of ICE
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// candidates is complete and and answer is available in LocalDescription.
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// Installs an OnDataChannel callback that creates a webRTCConn and passes it to
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// datachannelHandler.
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func makePeerConnectionFromOffer(sdp *webrtc.SessionDescription, config *webrtc.Configuration) (*webrtc.PeerConnection, error) {
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errChan := make(chan error)
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answerChan := make(chan *webrtc.SessionDescription)
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pc, err := webrtc.NewPeerConnection(config)
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if err != nil {
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return nil, fmt.Errorf("accept: NewPeerConnection: %s", err)
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}
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pc.OnNegotiationNeeded = func() {
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panic("OnNegotiationNeeded")
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}
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pc.OnIceComplete = func() {
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answerChan <- pc.LocalDescription()
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}
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pc.OnDataChannel = func(dc *data.Channel) {
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log.Println("OnDataChannel")
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pr, pw := io.Pipe()
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conn.pr = pr
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dc := conn.dc
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dc.OnOpen = func() {
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log.Println("OnOpen channel")
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}
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@ -105,7 +129,6 @@ func datachannelHandler(conn *webRTCConn) {
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pw.Close()
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}
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dc.OnMessage = func(msg []byte) {
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// log.Printf("OnMessage channel %d %+q", len(msg), msg)
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log.Printf("OnMessage <--- %d bytes", len(msg))
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n, err := pw.Write(msg)
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if err != nil {
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@ -116,33 +139,58 @@ func datachannelHandler(conn *webRTCConn) {
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}
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}
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go copyLoop(conn, or)
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conn := &webRTCConn{pc: pc, dc: dc, pr: pr}
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go datachannelHandler(conn)
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}
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func makePeerConnection(config *webrtc.Configuration) (*webrtc.PeerConnection, error) {
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pc, err := webrtc.NewPeerConnection(config)
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err = pc.SetRemoteDescription(sdp)
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if err != nil {
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log.Printf("NewPeerConnection: %s", err)
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pc.Close()
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return nil, fmt.Errorf("accept: SetRemoteDescription: %s", err)
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}
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log.Println("sdp offer successfully received.")
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go func() {
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log.Println("Generating answer...")
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answer, err := pc.CreateAnswer() // blocking
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if err != nil {
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errChan <- err
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return
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}
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err = pc.SetLocalDescription(answer)
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if err != nil {
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errChan <- err
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return
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}
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}()
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// Wait until answer is ready.
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select {
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case err = <-errChan:
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pc.Close()
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return nil, err
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case <-answerChan:
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}
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pc.OnNegotiationNeeded = func() {
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panic("OnNegotiationNeeded")
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}
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pc.OnDataChannel = func(dc *data.Channel) {
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log.Println("OnDataChannel")
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datachannelHandler(&webRTCConn{pc: pc, dc: dc})
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}
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pc.OnIceComplete = func() {
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log.Printf("----------------")
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fmt.Fprintln(logFile, pc.LocalDescription().Serialize())
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log.Printf("----------------")
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}
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return pc, nil
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}
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func readSignalingMessages(signalChan chan *webrtc.SessionDescription, f *os.File) {
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s := bufio.NewScanner(f)
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// Create a signaling named pipe and feed offers from it into
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// makePeerConnectionFromOffer.
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func receiveSignalsFIFO(filename string, config *webrtc.Configuration) error {
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err := syscall.Mkfifo(filename, 0600)
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if err != nil {
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if err.(syscall.Errno) != syscall.EEXIST {
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return err
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}
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}
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signalFile, err := os.OpenFile(filename, os.O_RDONLY, 0600)
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if err != nil {
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return err
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}
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defer signalFile.Close()
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s := bufio.NewScanner(signalFile)
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for s.Scan() {
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msg := s.Text()
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sdp := webrtc.DeserializeSessionDescription(msg)
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@ -150,62 +198,18 @@ func readSignalingMessages(signalChan chan *webrtc.SessionDescription, f *os.Fil
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log.Printf("ignoring invalid signal message %+q", msg)
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continue
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}
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signalChan <- sdp
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pc, err := makePeerConnectionFromOffer(sdp, config)
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if err != nil {
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log.Printf("makePeerConnectionFromOffer: %s", err)
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continue
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}
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if err := s.Err(); err != nil {
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log.Printf("signal FIFO: %s", err)
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// Write offer to log for manual signaling.
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log.Printf("----------------")
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fmt.Fprintln(logFile, pc.LocalDescription().Serialize())
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log.Printf("----------------")
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}
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}
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func generateAnswer(pc *webrtc.PeerConnection) {
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fmt.Println("Generating answer...")
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answer, err := pc.CreateAnswer() // blocking
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if err != nil {
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fmt.Println(err)
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return
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}
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pc.SetLocalDescription(answer)
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}
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func listenWebRTC(config *webrtc.Configuration, signal string) (*os.File, error) {
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err := syscall.Mkfifo(signal, 0600)
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if err != nil {
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if err.(syscall.Errno) != syscall.EEXIST {
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return nil, err
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}
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}
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signalFile, err := os.OpenFile(signal, os.O_RDONLY, 0600)
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if err != nil {
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return nil, err
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}
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//defer signalFile.Close()
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var signalChan = make(chan *webrtc.SessionDescription)
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go func() {
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for {
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select {
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case sdp := <-signalChan:
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pc, err := makePeerConnection(config)
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if err != nil {
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log.Printf("makePeerConnection: %s", err)
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break
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}
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err = pc.SetRemoteDescription(sdp)
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if err != nil {
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fmt.Println("ERROR", err)
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break
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}
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fmt.Println("sdp offer successfully received.")
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go generateAnswer(pc)
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}
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}
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}()
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go readSignalingMessages(signalChan, signalFile)
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log.Printf("waiting for offer")
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return signalFile, nil
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return s.Err()
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}
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func main() {
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@ -228,18 +232,19 @@ func main() {
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webRTCConfig := webrtc.NewConfiguration(webrtc.OptionIceServer("stun:stun.l.google.com:19302"))
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listeners := make([]*os.File, 0)
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// Start FIFO-based signaling receiver.
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go func() {
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err := receiveSignalsFIFO("signal", webRTCConfig)
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if err != nil {
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log.Printf("receiveSignalsFIFO: %s", err)
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}
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}()
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for _, bindaddr := range ptInfo.Bindaddrs {
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switch bindaddr.MethodName {
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case ptMethodName:
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ln, err := listenWebRTC(webRTCConfig, "signal") // meh
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if err != nil {
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pt.SmethodError(bindaddr.MethodName, err.Error())
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break
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}
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bindaddr.Addr.Port = 12345 // lies!!!
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pt.Smethod(bindaddr.MethodName, bindaddr.Addr)
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listeners = append(listeners, ln)
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default:
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pt.SmethodError(bindaddr.MethodName, "no such method")
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}
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@ -260,9 +265,6 @@ func main() {
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case sig = <-sigChan:
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}
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}
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for _, ln := range listeners {
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ln.Close()
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}
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if sig == syscall.SIGTERM {
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return
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