mirror of
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git
synced 2025-10-13 20:11:19 -04:00
Add comments and improve logging
This commit is contained in:
itchyonion
parent
fb35e80b0a
commit
5dd0a31d95
1 changed files with 69 additions and 38 deletions
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@ -51,30 +51,37 @@ import (
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"github.com/pion/webrtc/v3"
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)
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const DefaultBrokerURL = "https://snowflake-broker.torproject.net/"
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const DefaultNATProbeURL = "https://snowflake-broker.torproject.net:8443/probe"
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const DefaultRelayURL = "wss://snowflake.bamsoftware.com/"
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const DefaultSTUNURL = "stun:stun.l.google.com:19302"
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const DefaultProxyType = "standalone"
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const pollInterval = 5 * time.Second
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const (
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DefaultBrokerURL = "https://snowflake-broker.torproject.net/"
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DefaultNATProbeURL = "https://snowflake-broker.torproject.net:8443/probe"
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DefaultRelayURL = "wss://snowflake.bamsoftware.com/"
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DefaultSTUNURL = "stun:stun.l.google.com:19302"
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DefaultProxyType = "standalone"
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)
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const (
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// NATUnknown represents a NAT type which is unknown.
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NATUnknown = "unknown"
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// NATRestricted represents a restricted NAT.
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NATRestricted = "restricted"
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// NATUnrestricted represents an unrestricted NAT.
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NATUnrestricted = "unrestricted"
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)
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// amount of time after sending an SDP answer before the proxy assumes the
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// client is not going to connect
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const dataChannelTimeout = 20 * time.Second
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const (
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pollInterval = 5 * time.Second
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const readLimit = 100000 //Maximum number of bytes to be read from an HTTP request
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// Amount of time after sending an SDP answer before the proxy assumes the
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// client is not going to connect
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dataChannelTimeout = 20 * time.Second
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//Maximum number of bytes to be read from an HTTP request
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readLimit = 100000
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sessionIDLength = 16
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)
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var broker *SignalingServer
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@ -90,10 +97,6 @@ func getCurrentNATType() string {
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return currentNATType
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}
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const (
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sessionIDLength = 16
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)
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var (
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tokens *tokens_t
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config webrtc.Configuration
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@ -184,16 +187,15 @@ func newSignalingServer(rawURL string, keepLocalAddresses bool) (*SignalingServe
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// Post sends a POST request to the SignalingServer
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func (s *SignalingServer) Post(path string, payload io.Reader) ([]byte, error) {
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req, err := http.NewRequest("POST", path, payload)
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if err != nil {
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return nil, err
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}
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resp, err := s.transport.RoundTrip(req)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("remote returned status code %d", resp.StatusCode)
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}
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@ -202,6 +204,8 @@ func (s *SignalingServer) Post(path string, payload io.Reader) ([]byte, error) {
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return limitedRead(resp.Body, readLimit)
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}
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// pollOffer communicates the proxy's capabilities with broker
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// and retrieves a compatible SDP offer
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func (s *SignalingServer) pollOffer(sid string, proxyType string, acceptedRelayPattern string, shutdown chan struct{}) (*webrtc.SessionDescription, string) {
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brokerPath := s.url.ResolveReference(&url.URL{Path: "proxy"})
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@ -221,6 +225,7 @@ func (s *SignalingServer) pollOffer(sid string, proxyType string, acceptedRelayP
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log.Printf("Error encoding poll message: %s", err.Error())
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return nil, ""
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}
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resp, err := s.Post(brokerPath.String(), bytes.NewBuffer(body))
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if err != nil {
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log.Printf("error polling broker: %s", err.Error())
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@ -239,7 +244,6 @@ func (s *SignalingServer) pollOffer(sid string, proxyType string, acceptedRelayP
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return nil, ""
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}
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return offer, relayURL
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}
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}
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}
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@ -247,7 +251,6 @@ func (s *SignalingServer) pollOffer(sid string, proxyType string, acceptedRelayP
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}
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func (s *SignalingServer) sendAnswer(sid string, pc *webrtc.PeerConnection) error {
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brokerPath := s.url.ResolveReference(&url.URL{Path: "answer"})
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ld := pc.LocalDescription()
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if !s.keepLocalAddresses {
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ld = &webrtc.SessionDescription{
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@ -255,14 +258,18 @@ func (s *SignalingServer) sendAnswer(sid string, pc *webrtc.PeerConnection) erro
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SDP: util.StripLocalAddresses(ld.SDP),
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}
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}
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answer, err := util.SerializeSessionDescription(ld)
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if err != nil {
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return err
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}
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body, err := messages.EncodeAnswerRequest(answer, sid)
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if err != nil {
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return err
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}
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brokerPath := s.url.ResolveReference(&url.URL{Path: "answer"})
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resp, err := s.Post(brokerPath.String(), bytes.NewBuffer(body))
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if err != nil {
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return fmt.Errorf("error sending answer to broker: %s", err.Error())
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@ -307,8 +314,8 @@ func copyLoop(c1 io.ReadWriteCloser, c2 io.ReadWriteCloser, shutdown chan struct
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// We pass conn.RemoteAddr() as an additional parameter, rather than calling
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// conn.RemoteAddr() inside this function, as a workaround for a hang that
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// otherwise occurs inside of conn.pc.RemoteDescription() (called by
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// RemoteAddr). https://bugs.torproject.org/18628#comment:8
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// otherwise occurs inside conn.pc.RemoteDescription() (called by RemoteAddr).
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// https://bugs.torproject.org/18628#comment:8
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func (sf *SnowflakeProxy) datachannelHandler(conn *webRTCConn, remoteAddr net.Addr, relayURL string) {
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defer conn.Close()
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defer tokens.ret()
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@ -316,6 +323,7 @@ func (sf *SnowflakeProxy) datachannelHandler(conn *webRTCConn, remoteAddr net.Ad
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if relayURL == "" {
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relayURL = sf.RelayURL
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}
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u, err := url.Parse(relayURL)
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if err != nil {
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log.Fatalf("invalid relay url: %s", err)
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@ -336,8 +344,9 @@ func (sf *SnowflakeProxy) datachannelHandler(conn *webRTCConn, remoteAddr net.Ad
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log.Printf("error dialing relay: %s = %s", u.String(), err)
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return
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}
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wsConn := websocketconn.New(ws)
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log.Printf("connected to relay: %v", relayURL)
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log.Printf("Connected to relay: %v", relayURL)
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defer wsConn.Close()
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copyLoop(conn, wsConn, sf.shutdown)
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log.Printf("datachannelHandler ends")
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@ -367,6 +376,7 @@ func (sf *SnowflakeProxy) makeWebRTCAPI() *webrtc.API {
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// still have server reflexive candidates to fall back on
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settingsEngine.SetNAT1To1IPs([]string{sf.OutboundAddress}, webrtc.ICECandidateTypeHost)
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}
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settingsEngine.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
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return webrtc.NewAPI(webrtc.WithSettingEngine(settingsEngine))
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@ -386,20 +396,33 @@ func (sf *SnowflakeProxy) makePeerConnectionFromOffer(sdp *webrtc.SessionDescrip
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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.OnDataChannel(func(dc *webrtc.DataChannel) {
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log.Println("OnDataChannel")
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log.Printf("New Data Channel %s-%d\n", dc.Label(), dc.ID())
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close(dataChan)
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pr, pw := io.Pipe()
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conn := newWebRTCConn(pc, dc, pr, sf.EventDispatcher)
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dc.OnOpen(func() {
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log.Println("OnOpen channel")
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log.Printf("Data Channel %s-%d open\n", dc.Label(), dc.ID())
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if sf.OutboundAddress != "" {
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selectedCandidatePair, err := pc.SCTP().Transport().ICETransport().GetSelectedCandidatePair()
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if err != nil {
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log.Printf("Warning: couldn't get the selected candidate pair")
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}
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log.Printf("Selected Local Candidate: %s:%d", selectedCandidatePair.Local.Address, selectedCandidatePair.Local.Port)
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if sf.OutboundAddress != selectedCandidatePair.Local.Address {
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log.Printf("Warning: the IP address provided by --outbound-address is not used for establishing peerconnection")
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}
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}
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})
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dc.OnClose(func() {
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conn.lock.Lock()
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defer conn.lock.Unlock()
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log.Println("OnClose channel")
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log.Printf("Data Channel %s-%d close\n", dc.Label(), dc.ID())
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log.Println(conn.bytesLogger.ThroughputSummary())
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in, out := conn.bytesLogger.GetStat()
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conn.eventLogger.OnNewSnowflakeEvent(event.EventOnProxyConnectionOver{
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@ -437,7 +460,6 @@ func (sf *SnowflakeProxy) makePeerConnectionFromOffer(sdp *webrtc.SessionDescrip
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}
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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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log.Println("Generating answer...")
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answer, err := pc.CreateAnswer(nil)
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@ -458,8 +480,11 @@ func (sf *SnowflakeProxy) makePeerConnectionFromOffer(sdp *webrtc.SessionDescrip
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}
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return nil, err
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}
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// Wait for ICE candidate gathering to complete
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<-done
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log.Printf("Answer: \n\t%s", strings.ReplaceAll(pc.LocalDescription().SDP, "\n", "\n\t"))
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return pc, nil
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}
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@ -497,7 +522,7 @@ func (sf *SnowflakeProxy) makeNewPeerConnection(config webrtc.Configuration,
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pc.Close()
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return nil, err
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}
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log.Println("WebRTC: Created offer")
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log.Println("Probetest: Creating offer")
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// As of v3.0.0, pion-webrtc uses trickle ICE by default.
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// We have to wait for candidate gathering to complete
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@ -509,7 +534,7 @@ func (sf *SnowflakeProxy) makeNewPeerConnection(config webrtc.Configuration,
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pc.Close()
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return nil, err
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}
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log.Println("WebRTC: Set local description")
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log.Println("Probetest: Set local description")
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// Wait for ICE candidate gathering to complete
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<-done
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@ -523,6 +548,8 @@ func (sf *SnowflakeProxy) runSession(sid string) {
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tokens.ret()
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return
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}
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log.Printf("Received Offer From Broker: \n\t%s", strings.ReplaceAll(offer.SDP, "\n", "\n\t"))
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matcher := namematcher.NewNameMatcher(sf.RelayDomainNamePattern)
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parsedRelayURL, err := url.Parse(relayURL)
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if err != nil {
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@ -530,11 +557,13 @@ func (sf *SnowflakeProxy) runSession(sid string) {
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tokens.ret()
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return
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}
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if relayURL != "" && (!matcher.IsMember(parsedRelayURL.Hostname()) || (!sf.AllowNonTLSRelay && parsedRelayURL.Scheme != "wss")) {
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log.Printf("bad offer from broker: rejected Relay URL")
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tokens.ret()
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return
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}
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dataChan := make(chan struct{})
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dataChannelAdaptor := dataChannelHandlerWithRelayURL{RelayURL: relayURL, sf: sf}
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pc, err := sf.makePeerConnectionFromOffer(offer, config, dataChan, dataChannelAdaptor.datachannelHandler)
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@ -543,6 +572,7 @@ func (sf *SnowflakeProxy) runSession(sid string) {
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tokens.ret()
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return
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}
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err = broker.sendAnswer(sid, pc)
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if err != nil {
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log.Printf("error sending answer to client through broker: %s", err)
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@ -557,7 +587,7 @@ func (sf *SnowflakeProxy) runSession(sid string) {
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// destroy the peer connection and return the token.
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select {
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case <-dataChan:
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log.Println("Connection successful.")
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log.Println("Connection successful")
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case <-time.After(dataChannelTimeout):
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log.Println("Timed out waiting for client to open data channel.")
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if err := pc.Close(); err != nil {
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@ -622,11 +652,8 @@ func (sf *SnowflakeProxy) Start() error {
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}
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tokens = newTokens(sf.Capacity)
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// use probetest to determine NAT compatability
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sf.checkNATType(config, sf.NATProbeURL)
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currentNATTypeLoaded := getCurrentNATType()
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sf.EventDispatcher.OnNewSnowflakeEvent(&event.EventOnCurrentNATTypeDetermined{CurNATType: currentNATTypeLoaded})
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NatRetestTask := task.Periodic{
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@ -663,14 +690,16 @@ func (sf *SnowflakeProxy) Stop() {
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close(sf.shutdown)
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}
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// checkNATType use probetest to determine NAT compatability by
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// attempting to connect with a known symmetric NAT. If success,
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// it is considered "unrestricted". If timeout it is considered "restricted"
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func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL string) {
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probe, err := newSignalingServer(probeURL, false)
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if err != nil {
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log.Printf("Error parsing url: %s", err.Error())
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}
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// create offer
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// create offer used for probetest
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dataChan := make(chan struct{})
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pc, err := sf.makeNewPeerConnection(config, dataChan)
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if err != nil {
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@ -679,7 +708,7 @@ func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL str
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}
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offer := pc.LocalDescription()
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log.Printf("Offer: \n\t%s", strings.ReplaceAll(offer.SDP, "\n", "\n\t"))
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log.Printf("Probetest offer: \n\t%s", strings.ReplaceAll(offer.SDP, "\n", "\n\t"))
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sdp, err := util.SerializeSessionDescription(offer)
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if err != nil {
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log.Printf("Error encoding probe message: %s", err.Error())
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@ -692,6 +721,7 @@ func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL str
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log.Printf("Error encoding probe message: %s", err.Error())
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return
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}
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resp, err := probe.Post(probe.url.String(), bytes.NewBuffer(body))
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if err != nil {
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log.Printf("error polling probe: %s", err.Error())
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@ -703,11 +733,13 @@ func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL str
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log.Printf("Error reading probe response: %s", err.Error())
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return
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}
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answer, err := util.DeserializeSessionDescription(sdp)
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if err != nil {
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log.Printf("Error setting answer: %s", err.Error())
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return
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}
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err = pc.SetRemoteDescription(*answer)
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if err != nil {
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log.Printf("Error setting answer: %s", err.Error())
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@ -745,5 +777,4 @@ func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL str
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if err := pc.Close(); err != nil {
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log.Printf("error calling pc.Close: %v", err)
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}
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}
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