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Add covert-dtls to proxy and client with flags

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This commit is contained in:
theodorsm 2024-11-30 22:17:27 +01:00
parent ae5bd52821
commit 541e124194
8 changed files with 88 additions and 16 deletions
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35
client/lib/webrtc.go
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@ -11,10 +11,13 @@ import (
"sync"
"time"
"github.com/pion/dtls/v3"
"github.com/pion/ice/v4"
"github.com/pion/transport/v3"
"github.com/pion/transport/v3/stdnet"
"github.com/pion/webrtc/v4"
"github.com/theodorsm/covert-dtls/pkg/mimicry"
"github.com/theodorsm/covert-dtls/pkg/randomize"
"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/event"
"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/proxy"
@ -49,7 +52,7 @@ type WebRTCPeer struct {
func NewWebRTCPeer(
config *webrtc.Configuration, broker *BrokerChannel,
) (*WebRTCPeer, error) {
return NewWebRTCPeerWithEventsAndProxy(config, broker, nil, nil)
return NewWebRTCPeerWithEventsAndProxy(config, broker, nil, nil, false, false)
}
// Deprecated: Use NewWebRTCPeerWithEventsAndProxy Instead.
@ -57,7 +60,7 @@ func NewWebRTCPeerWithEvents(
config *webrtc.Configuration, broker *BrokerChannel,
eventsLogger event.SnowflakeEventReceiver,
) (*WebRTCPeer, error) {
return NewWebRTCPeerWithEventsAndProxy(config, broker, eventsLogger, nil)
return NewWebRTCPeerWithEventsAndProxy(config, broker, eventsLogger, nil, false, false)
}
// NewWebRTCPeerWithEventsAndProxy constructs a WebRTC PeerConnection to a snowflake proxy.
@ -68,6 +71,7 @@ func NewWebRTCPeerWithEvents(
func NewWebRTCPeerWithEventsAndProxy(
config *webrtc.Configuration, broker *BrokerChannel,
eventsLogger event.SnowflakeEventReceiver, proxy *url.URL,
dtlsRandomize bool, dtlsMimic bool,
) (*WebRTCPeer, error) {
if eventsLogger == nil {
eventsLogger = event.NewSnowflakeEventDispatcher()
@ -92,7 +96,7 @@ func NewWebRTCPeerWithEventsAndProxy(
connection.eventsLogger = eventsLogger
connection.proxy = proxy
err := connection.connect(config, broker)
err := connection.connect(config, broker, dtlsRandomize, dtlsMimic)
if err != nil {
connection.Close()
return nil, err
@ -166,10 +170,9 @@ func (c *WebRTCPeer) checkForStaleness(timeout time.Duration) {
// connect does the bulk of the work: gather ICE candidates, send the SDP offer to broker,
// receive an answer from broker, and wait for data channel to open
func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel) error {
func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel, dtlsRandomize bool, dtlsMimic bool) error {
log.Println(c.id, " connecting...")
err := c.preparePeerConnection(config, broker.keepLocalAddresses)
err := c.preparePeerConnection(config, broker.keepLocalAddresses, dtlsRandomize, dtlsMimic)
localDescription := c.pc.LocalDescription()
c.eventsLogger.OnNewSnowflakeEvent(event.EventOnOfferCreated{
WebRTCLocalDescription: localDescription,
@ -213,6 +216,8 @@ func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel
func (c *WebRTCPeer) preparePeerConnection(
config *webrtc.Configuration,
keepLocalAddresses bool,
dtlsRandomize bool,
dtlsMimic bool,
) error {
var err error
s := webrtc.SettingEngine{}
@ -245,6 +250,24 @@ func (c *WebRTCPeer) preparePeerConnection(
}
s.SetNet(vnet)
if dtlsRandomize {
rand := randomize.RandomizedMessageClientHello{RandomALPN: true}
s.SetDTLSClientHelloMessageHook(rand.Hook)
} else if dtlsMimic {
mimic := &mimicry.MimickedClientHello{}
profiles := []dtls.SRTPProtectionProfile{
dtls.SRTP_AES128_CM_HMAC_SHA1_80,
dtls.SRTP_AES128_CM_HMAC_SHA1_32,
dtls.SRTP_AEAD_AES_128_GCM,
dtls.SRTP_AEAD_AES_256_GCM,
dtls.SRTP_AES256_CM_SHA1_32,
dtls.SRTP_AES256_CM_SHA1_80,
}
s.SetSRTPProtectionProfiles(profiles...)
s.SetDTLSClientHelloMessageHook(mimic.Hook)
}
api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
c.pc, err = api.NewPeerConnection(*config)
if err != nil {