add --meek flag to client to toggle the domain fronted rendezvous

README.md

@@ -88,4 +88,11 @@ snowflake to just use a default relay.
 
 ### More
 
+To try using the Meek signaling channel (which will soon be fully ready),
+add the `--meek` flag like so:
+
+```
+ClientTransportPlugin snowflake exec ./client --meek
+```
+
 More documentation on the way.

client/meek-webrtc.go

@@ -1,5 +1,5 @@
-// Exchange WebRTC SessionDescriptions over meek.
-// Much of this source is extracted from meek-client.go.
+// Exchange WebRTC SessionDescriptions over a domain-fronted HTTP
+// signalling channel.
 package main
 
 import (
@@ -16,29 +16,26 @@ import (
 // roundtrip, including variables that may come from SOCKS args or from the
 // command line.
 type RequestInfo struct {
-	// What to put in the X-Session-ID header.
-	// SessionID string
-	// The URL to request.
+	// What to put in the X-Session-ID header - SessionID string
+	// The desired potentially filtered URL to request.
 	URL *url.URL
 	// The Host header to put in the HTTP request (optional and may be
 	// different from the host name in URL).
 	Host string
 }
 
-func NewRequestInfo(meekUrl string, front string) *RequestInfo {
+func NewRequestInfo(targetUrl string, front string) *RequestInfo {
 	info := new(RequestInfo)
-	requestUrl, err := url.Parse(meekUrl)
+	requestUrl, err := url.Parse(targetUrl)
 	if nil != err {
 		return nil
 	}
 	info.URL = requestUrl
 	info.Host = front
-	// info.URL.Host = front
-	// info.Host = info.URL.Host
 	return info
 }
 
-// Meek Signalling Channel
+// Meek Signalling Channel.
 type MeekChannel struct {
 	info *RequestInfo
 	// Used to make all requests.
@@ -58,24 +55,23 @@ func NewMeekChannel(info *RequestInfo) *MeekChannel {
 }
 
 // Do an HTTP roundtrip using the payload data in buf.
-func (m *MeekChannel) roundTripHTTP(buf []byte) (*http.Response, error) {
+func (mc *MeekChannel) roundTripHTTP(buf []byte) (*http.Response, error) {
 	// Compose an innocent looking request.
-	req, err := http.NewRequest("POST", m.info.Host+"/reg/123", bytes.NewReader(buf))
+	req, err := http.NewRequest("POST", mc.info.Host+"/reg/123", bytes.NewReader(buf))
 	if nil != err {
 		return nil, err
 	}
-	// Set actually desired target host.
-	req.Host = m.info.URL.String()
+	// Set actually desired host in the request.
+	req.Host = mc.info.URL.String()
 	// req.Header.Set("X-Session-Id", m.info.SessionID)
-	return m.transport.RoundTrip(req)
+	return mc.transport.RoundTrip(req)
 }
 
 // Send an SDP offer to the meek facilitator, and wait for an SDP answer from
 // the assigned proxy in the response.
-func (m *MeekChannel) Negotiate(offer *webrtc.SessionDescription) (
+func (mc *MeekChannel) Negotiate(offer *webrtc.SessionDescription) (
 	*webrtc.SessionDescription, error) {
-	buf := []byte(offer.Serialize())
-	resp, err := m.roundTripHTTP(buf)
+	resp, err := mc.roundTripHTTP([]byte(offer.Serialize()))
 	if nil != err {
 		return nil, err
 	}
@@ -85,11 +81,11 @@ func (m *MeekChannel) Negotiate(offer *webrtc.SessionDescription) (
 	if nil != err {
 		return nil, err
 	}
-	log.Println("MeekChannel Body: ", string(body))
 	answer := webrtc.DeserializeSessionDescription(string(body))
 	return answer, nil
 }
 
+
 // Simple interim non-fronting HTTP POST negotiation, to be removed when more
 // general fronting is present.
 func sendOfferHTTP(url string, offer *webrtc.SessionDescription) (*webrtc.SessionDescription, error) {

client/snowflake.go

@@ -25,14 +25,15 @@ import (
 // Hard-coded meek signalling channel for now.
 // TODO: expose as param
 const (
-	MEEK_URL     = "snowflake-reg.appspot.com"
-	FRONT_DOMAIN = "https://www.google.com"
-	// FRONT_DOMAIN = "https://www.google.com"
+	// Go fully requires the protocol to make url spec
+	FRONT_URL = "https://www.google.com"
+	BROKER_URL     = "snowflake-reg.appspot.com"
 )
 
 var ptInfo pt.ClientInfo
 var logFile *os.File
 var offerURL string
+var meekEnabled bool
 
 // When a connection handler starts, +1 is written to this channel; when it
 // ends, -1 is written.
@@ -160,7 +161,6 @@ func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
 		close(openChan)
 	}
 	dc.OnMessage = func(msg []byte) {
-		// log.Printf("OnMessage channel %d %+q", len(msg), msg)
 		log.Printf("OnMessage <--- %d bytes", len(msg))
 		n, err := pw.Write(msg)
 		if err != nil {
@@ -180,20 +180,22 @@ func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
 		fmt.Fprintln(logFile, "\n"+offer.Serialize()+"\n")
 		log.Printf("----------------")
 		go func() {
-			// log.Printf("Sending offer via meek...")
-			// answer, err := meek.Negotiate(pc.LocalDescription())
-			// if nil != err {
-			// 	log.Printf("Signalling error: %s", err)
-			// }
-			// if nil == answer {
-			// 	log.Printf("No answer received from meek channel.")
-			// } else {
-			// 	// TODO: Once this is correct, uncomment and remove copy-paste
-			// 	// signalling.
-			// 	log.Println("Recieved answer from Meek channel: \n",
-			// 		answer.Serialize())
-			// 	// signalChan <- answer
-			// }
+			if meekEnabled {
+				log.Println("Sending offer via meek channel...\nTarget URL: ", BROKER_URL,
+					"\nFront URL:  ", FRONT_URL)
+				answer, err := meek.Negotiate(pc.LocalDescription())
+				if nil != err {
+					log.Printf("MeekChannel signaling error: %s", err)
+				}
+				if nil == answer {
+					log.Printf("MeekChannel: No answer received.")
+				} else {
+					log.Println("Recieved answer from Meek channel: \n\n",
+						answer.Serialize(), "\n")
+					// TODO: Once this is correct, uncomment and remove copy-paste stuff.
+					// signalChan <- answer
+				}
+			}
 			if offerURL != "" {
 				answer, err := sendOfferHTTP(offerURL, offer)
 				if err != nil {
@@ -253,15 +255,12 @@ func handler(conn *pt.SocksConn) error {
 	}()
 	defer conn.Close()
 
-	// go func() {
-	// }()
 	// Prepare meek signalling channel.
-	info := NewRequestInfo(MEEK_URL, FRONT_DOMAIN)
+	info := NewRequestInfo(BROKER_URL, FRONT_URL)
 	meek := NewMeekChannel(info)
 
 	config := webrtc.NewConfiguration(
 		webrtc.OptionIceServer("stun:stun.l.google.com:19302"))
-	// remote, err := dialWebRTC(config, nil)
 	remote, err := dialWebRTC(config, meek)
 	if err != nil {
 		conn.Reject()
@@ -322,7 +321,8 @@ func readSignalingMessages(f *os.File) {
 func main() {
 	var err error
 
-	flag.StringVar(&offerURL, "url", "", "do signaling through URL")
+	flag.StringVar(&offerURL, "url", "", "do signalling through URL")
+	flag.BoolVar(&meekEnabled, "meek", false, "use domain fronted signaling")
 	flag.Parse()
 
 	logFile, err = os.OpenFile("snowflake.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)