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improvement: use SetIPFilter for local addrs

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Closes https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40271.
Supersedes https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/merge_requests/417.

This simplifies the code and (probably) removes the need for
`StripLocalAddresses`, although makes us more dependent on Pion.

Signed-off-by: Cecylia Bocovich <cohosh@torproject.org>
This commit is contained in:
WofWca 2024-11-25 01:43:29 +04:00 • committed by Cecylia Bocovich
parent 43799819a1
commit ae5bd52821
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GPG key ID: 009DE379FD9B7B90
6 changed files with 56 additions and 32 deletions
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2
proxy/lib/proxy-go_test.go
View file

@ -336,7 +336,7 @@ func TestBrokerInteractions(t *testing.T) {
Convey("Proxy connections to broker", t, func() {
var err error
broker, err = newSignalingServer("localhost", false)
broker, err = newSignalingServer("localhost")
So(err, ShouldBeNil)
tokens = newTokens(0)

30
proxy/lib/snowflake.go
View file

@ -193,15 +193,13 @@ func limitedRead(r io.Reader, limit int64) ([]byte, error) {
// SignalingServer keeps track of the SignalingServer in use by the Snowflake
type SignalingServer struct {
url *url.URL
transport http.RoundTripper
keepLocalAddresses bool
url *url.URL
transport http.RoundTripper
}
func newSignalingServer(rawURL string, keepLocalAddresses bool) (*SignalingServer, error) {
func newSignalingServer(rawURL string) (*SignalingServer, error) {
var err error
s := new(SignalingServer)
s.keepLocalAddresses = keepLocalAddresses
s.url, err = url.Parse(rawURL)
if err != nil {
return nil, fmt.Errorf("invalid broker url: %s", err)
@ -271,13 +269,6 @@ func (s *SignalingServer) pollOffer(sid string, proxyType string, acceptedRelayP
// and wait for its response
func (s *SignalingServer) sendAnswer(sid string, pc *webrtc.PeerConnection) error {
ld := pc.LocalDescription()
if !s.keepLocalAddresses {
ld = &webrtc.SessionDescription{
Type: ld.Type,
SDP: util.StripLocalAddresses(ld.SDP),
}
}
answer, err := util.SerializeSessionDescription(ld)
if err != nil {
return err
@ -397,6 +388,17 @@ func (d dataChannelHandlerWithRelayURL) datachannelHandler(conn *webRTCConn, rem
func (sf *SnowflakeProxy) makeWebRTCAPI() *webrtc.API {
settingsEngine := webrtc.SettingEngine{}
if !sf.KeepLocalAddresses {
settingsEngine.SetIPFilter(func(ip net.IP) (keep bool) {
// `IsLoopback()` and `IsUnspecified` are likely not neded here,
// but let's keep them just in case.
// FYI there is similar code in other files in this project.
keep = !util.IsLocal(ip) && !ip.IsLoopback() && !ip.IsUnspecified()
return
})
}
settingsEngine.SetIncludeLoopbackCandidate(sf.KeepLocalAddresses)
// Use the SetNet setting https://pkg.go.dev/github.com/pion/webrtc/v3#SettingEngine.SetNet
// to get snowflake working in shadow (where the AF_NETLINK family is not implemented).
// These two lines of code functionally revert a new change in pion by silently ignoring
@ -727,7 +729,7 @@ func (sf *SnowflakeProxy) Start() error {
sf.periodicProxyStats = newPeriodicProxyStats(sf.SummaryInterval, sf.EventDispatcher, sf.bytesLogger)
sf.EventDispatcher.AddSnowflakeEventListener(sf.periodicProxyStats)
broker, err = newSignalingServer(sf.BrokerURL, sf.KeepLocalAddresses)
broker, err = newSignalingServer(sf.BrokerURL)
if err != nil {
return fmt.Errorf("error configuring broker: %s", err)
}
@ -805,7 +807,7 @@ func (sf *SnowflakeProxy) Stop() {
func (sf *SnowflakeProxy) checkNATType(config webrtc.Configuration, probeURL string) error {
log.Printf("Checking our NAT type, contacting NAT check probe server at \"%v\"...", probeURL)
probe, err := newSignalingServer(probeURL, false)
probe, err := newSignalingServer(probeURL)
if err != nil {
return fmt.Errorf("Error parsing url: %w", err)
}