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fix(probetest): wrong "restricted" sometimes

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Closes https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40387
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WofWca 2024-09-23 12:22:06 +04:00 • committed by Shelikhoo
parent d346639eda
commit 5c7bdcea77
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1 changed files with 25 additions and 9 deletions
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34
probetest/probetest.go
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@ -29,9 +29,10 @@ import (
)
const (
readLimit = 100000 //Maximum number of bytes to be read from an HTTP request
dataChannelTimeout = 20 * time.Second //time after which we assume proxy data channel will not open
defaultStunUrl = "stun:stun.l.google.com:19302" //default STUN URL
readLimit = 100000 //Maximum number of bytes to be read from an HTTP request
dataChannelOpenTimeout = 20 * time.Second //time after which we assume proxy data channel will not open
dataChannelCloseTimeout = 5 * time.Second //how long to wait after the data channel has been open before closing the peer connection.
defaultStunUrl = "stun:stun.l.google.com:19302" //default STUN URL
)
type ProbeHandler struct {
@ -46,7 +47,7 @@ func (h ProbeHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// Create a PeerConnection from an SDP offer. Blocks until the gathering of ICE
// candidates is complete and the answer is available in LocalDescription.
func makePeerConnectionFromOffer(stunURL string, sdp *webrtc.SessionDescription,
dataChan chan struct{}, iceGatheringTimeout time.Duration) (*webrtc.PeerConnection, error) {
dataChanOpen chan struct{}, dataChanClosed chan struct{}, iceGatheringTimeout time.Duration) (*webrtc.PeerConnection, error) {
settingsEngine := webrtc.SettingEngine{}
// Use the SetNet setting https://pkg.go.dev/github.com/pion/webrtc/v3#SettingEngine.SetNet
@ -69,9 +70,10 @@ func makePeerConnectionFromOffer(stunURL string, sdp *webrtc.SessionDescription,
}
pc.OnDataChannel(func(dc *webrtc.DataChannel) {
dc.OnOpen(func() {
close(dataChan)
close(dataChanOpen)
})
dc.OnClose(func() {
close(dataChanClosed)
dc.Close()
})
})
@ -140,11 +142,12 @@ func probeHandler(stunURL string, w http.ResponseWriter, r *http.Request) {
return
}
dataChan := make(chan struct{})
dataChanOpen := make(chan struct{})
dataChanClosed := make(chan struct{})
// TODO refactor: DRY this must be below `ResponseHeaderTimeout` in proxy
// https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/blob/e1d9b4ace69897521cc29585b5084c5f4d1ce874/proxy/lib/snowflake.go#L207
iceGatheringTimeout := 10 * time.Second
pc, err := makePeerConnectionFromOffer(stunURL, sdp, dataChan, iceGatheringTimeout)
pc, err := makePeerConnectionFromOffer(stunURL, sdp, dataChanOpen, dataChanClosed, iceGatheringTimeout)
if err != nil {
log.Printf("Error making WebRTC connection: %s", err)
w.WriteHeader(http.StatusInternalServerError)
@ -184,11 +187,24 @@ func probeHandler(stunURL string, w http.ResponseWriter, r *http.Request) {
// destroy the peer connection and return the token.
closePcOnReturn = false
go func() {
timer := time.NewTimer(dataChannelTimeout)
timer := time.NewTimer(dataChannelOpenTimeout)
defer timer.Stop()
select {
case <-dataChan:
case <-dataChanOpen:
// Let's not close the `PeerConnection` immediately now,
// instead let's wait for the peer (or timeout)
// to close the connection,
// in order to ensure that the DataChannel also gets opened
// on the proxy's side.
// Otherwise the proxy might receive the "close PeerConnection"
// "event" before they receive "dataChannel.OnOpen",
// which would wrongly result in a "restricted" NAT.
// See https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40387
select {
case <-dataChanClosed:
case <-time.After(dataChannelCloseTimeout):
}
case <-timer.C:
}