add client side support for extra data based client id

client/lib/rendezvous.go

@@ -13,6 +13,8 @@ import (
 	"sync"
 	"time"
 
+	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/turbotunnel"
+
 	"github.com/pion/webrtc/v4"
 	utls "github.com/refraction-networking/utls"
 
@@ -251,6 +253,7 @@ type WebRTCDialer struct {
 
 	eventLogger  event.SnowflakeEventReceiver
 	proxy        *url.URL
+	connectionID turbotunnel.ClientID
 }
 
 // Deprecated: Use NewWebRTCDialerWithNatPolicyAndEventsAndProxy instead
@@ -281,7 +284,6 @@ func NewWebRTCDialerWithEventsAndProxy(broker *BrokerChannel, iceServers []webrt
 	)
 }
 
-// NewWebRTCDialerWithNatPolicyAndEventsAndProxy constructs a new WebRTCDialer.
 func NewWebRTCDialerWithNatPolicyAndEventsAndProxy(
 	broker *BrokerChannel,
 	natPolicy *NATPolicy,
@@ -289,6 +291,27 @@ func NewWebRTCDialerWithNatPolicyAndEventsAndProxy(
 	max int,
 	eventLogger event.SnowflakeEventReceiver,
 	proxy *url.URL,
+) *WebRTCDialer {
+	return NewWebRTCDialerWithNatPolicyAndEventsAndProxyAndClientID(
+		broker,
+		natPolicy,
+		iceServers,
+		max,
+		eventLogger,
+		proxy,
+		turbotunnel.NewClientID(),
+	)
+}
+
+// NewWebRTCDialerWithNatPolicyAndEventsAndProxy constructs a new WebRTCDialer.
+func NewWebRTCDialerWithNatPolicyAndEventsAndProxyAndClientID(
+	broker *BrokerChannel,
+	natPolicy *NATPolicy,
+	iceServers []webrtc.ICEServer,
+	max int,
+	eventLogger event.SnowflakeEventReceiver,
+	proxy *url.URL,
+	clientID turbotunnel.ClientID,
 ) *WebRTCDialer {
 	config := webrtc.Configuration{
 		ICEServers: iceServers,
@@ -302,6 +325,7 @@ func NewWebRTCDialerWithNatPolicyAndEventsAndProxy(
 
 		eventLogger:  eventLogger,
 		proxy:        proxy,
+		connectionID: clientID,
 	}
 }
 
@@ -309,9 +333,7 @@ func NewWebRTCDialerWithNatPolicyAndEventsAndProxy(
 func (w WebRTCDialer) Catch() (*WebRTCPeer, error) {
 	// TODO: [#25591] Fetch ICE server information from Broker.
 	// TODO: [#25596] Consider TURN servers here too.
-	return NewWebRTCPeerWithNatPolicyAndEventsAndProxy(
-		w.webrtcConfig, w.BrokerChannel, w.natPolicy, w.eventLogger, w.proxy,
-	)
+	return NewWebRTCPeerWithEventsAndProxy(w.webrtcConfig, w.BrokerChannel, w.eventLogger, w.proxy)
 }
 
 // GetMax returns the maximum number of snowflakes to collect.

client/lib/snowflake.go

@@ -78,6 +78,8 @@ type Transport struct {
 	// EventDispatcher is the event bus for snowflake events.
 	// When an important event happens, it will be distributed here.
 	eventDispatcher event.SnowflakeEventDispatcher
+
+	clientID turbotunnel.ClientID
 }
 
 // ClientConfig defines how the SnowflakeClient will connect to the broker and Snowflake proxies.
@@ -164,7 +166,11 @@ func NewSnowflakeClient(config ClientConfig) (*Transport, error) {
 		max = config.Max
 	}
 	eventsLogger := event.NewSnowflakeEventDispatcher()
-	transport := &Transport{dialer: NewWebRTCDialerWithNatPolicyAndEventsAndProxy(broker, natPolicy, iceServers, max, eventsLogger, config.CommunicationProxy), eventDispatcher: eventsLogger}
+	clientID := turbotunnel.NewClientID()
+	transport := &Transport{
+		dialer:          NewWebRTCDialerWithNatPolicyAndEventsAndProxy(broker, natPolicy, iceServers, max, eventsLogger, config.CommunicationProxy),
+		eventDispatcher: eventsLogger, clientID: clientID,
+	}
 
 	return transport, nil
 }
@@ -198,7 +204,7 @@ func (t *Transport) Dial() (net.Conn, error) {
 
 	// Create a new smux session
 	log.Printf("---- SnowflakeConn: starting a new session ---")
-	pconn, sess, err := newSession(snowflakes)
+	pconn, sess, err := newSession(snowflakes, t.clientID)
 	if err != nil {
 		return nil, err
 	}
@@ -324,8 +330,11 @@ func parseIceServers(addresses []string) []webrtc.ICEServer {
 // newSession returns a new smux.Session and the net.PacketConn it is running
 // over. The net.PacketConn successively connects through Snowflake proxies
 // pulled from snowflakes.
-func newSession(snowflakes SnowflakeCollector) (net.PacketConn, *smux.Session, error) {
+func newSession(snowflakes SnowflakeCollector, clientIDCandid turbotunnel.ClientID) (net.PacketConn, *smux.Session, error) {
 	clientID := turbotunnel.NewClientID()
+	if clientIDCandid != (turbotunnel.ClientID{}) {
+		clientID = clientIDCandid
+	}
 
 	// We build a persistent KCP session on a sequence of ephemeral WebRTC
 	// connections. This dialContext tells RedialPacketConn how to get a new
@@ -342,9 +351,8 @@ func newSession(snowflakes SnowflakeCollector) (net.PacketConn, *smux.Session, e
 		log.Println("---- Handler: snowflake assigned ----")
 		log.Printf("activeTransportMode = %c \n", conn.activeTransportMode)
 		if conn.activeTransportMode == 'u' {
-			packetIDConn := newPacketClientIDConn(clientID, conn)
 			packetConnWrapper := &packetConnWrapper{
-				ReadWriter: packetIDConn,
+				ReadWriter: conn,
 				remoteAddr: dummyAddr{},
 				localAddr:  dummyAddr{},
 			}

client/lib/webrtc.go

@@ -19,6 +19,7 @@ import (
 
 	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/event"
 	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/proxy"
+	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/turbotunnel"
 	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/util"
 )
 
@@ -46,6 +47,7 @@ type WebRTCPeer struct {
 	proxy        *url.URL
 
 	activeTransportMode byte
+	connectionID        turbotunnel.ClientID
 }
 
 // Deprecated: Use NewWebRTCPeerWithNatPolicyAndEventsAndProxy Instead.
@@ -77,15 +79,30 @@ func NewWebRTCPeerWithEventsAndProxy(
 	)
 }
 
+func NewWebRTCPeerWithNatPolicyAndEventsAndProxy(
+	config *webrtc.Configuration,
+	broker *BrokerChannel, natPolicy *NATPolicy, eventsLogger event.SnowflakeEventReceiver, proxy *url.URL,
+) (*WebRTCPeer, error) {
+	return NewWebRTCPeerWithNatPolicyAndEventsProxyAndClientID(
+		config,
+		broker,
+		natPolicy,
+		eventsLogger,
+		proxy,
+		turbotunnel.ClientID{},
+	)
+}
+
 // NewWebRTCPeerWithNatPolicyAndEventsAndProxy constructs
 // a WebRTC PeerConnection to a snowflake proxy.
 //
 // The creation of the peer handles the signaling to the Snowflake broker, including
 // the exchange of SDP information, the creation of a PeerConnection, and the establishment
 // of a DataChannel to the Snowflake proxy.
-func NewWebRTCPeerWithNatPolicyAndEventsAndProxy(
-	config *webrtc.Configuration, broker *BrokerChannel, natPolicy *NATPolicy,
-	eventsLogger event.SnowflakeEventReceiver, proxy *url.URL,
+// connectionID is the hinted ID for the connection.
+func NewWebRTCPeerWithNatPolicyAndEventsProxyAndClientID(config *webrtc.Configuration,
+	broker *BrokerChannel, natPolicy *NATPolicy, eventsLogger event.SnowflakeEventReceiver, proxy *url.URL,
+	clientID turbotunnel.ClientID,
 ) (*WebRTCPeer, error) {
 	if eventsLogger == nil {
 		eventsLogger = event.NewSnowflakeEventDispatcher()
@@ -109,6 +126,7 @@ func NewWebRTCPeerWithNatPolicyAndEventsAndProxy(
 
 	connection.eventsLogger = eventsLogger
 	connection.proxy = proxy
+	connection.connectionID = clientID
 
 	err := connection.connect(config, broker, natPolicy)
 	if err != nil {
@@ -307,7 +325,7 @@ func (c *WebRTCPeer) preparePeerConnection(
 		maxRetransmissionVal := uint16(0)
 		maxRetransmission = &maxRetransmissionVal
 	}
-	protocol := fmt.Sprintf("%c", c.activeTransportMode)
+	protocol := fmt.Sprintf("%c %s", c.activeTransportMode, c.connectionID.String())
 	dataChannelOptions := &webrtc.DataChannelInit{
 		Ordered:        &ordered,
 		Protocol:       &protocol,