s/MeekChannel/BrokerChannel (close #14) and more informative TODOs

client/rendezvous.go

@@ -1,5 +1,6 @@
-// Exchange WebRTC SessionDescriptions over a domain-fronted HTTP
-// signaling channel.
+// WebRTC Rendezvous requires the exchange of SessionDescriptions between
+// peers. This file contains the domain-fronted HTTP signaling mechanism
+// between the client and a desired Broker.
 package main
 
 import (
@@ -12,8 +13,8 @@ import (
 	"github.com/keroserene/go-webrtc"
 )
 
-// Meek Signalling Channel.
-type MeekChannel struct {
+// Signalling Channel to the Broker.
+type BrokerChannel struct {
 	// The Host header to put in the HTTP request (optional and may be
 	// different from the host name in URL).
 	Host      string
@@ -21,50 +22,50 @@ type MeekChannel struct {
 	transport http.Transport // Used to make all requests.
 }
 
-// Construct a new MeekChannel, where:
+// Construct a new BrokerChannel, where:
 // |broker| is the full URL of the facilitating program which assigns proxies
 // to clients, and |front| is the option fronting domain.
-func NewMeekChannel(broker string, front string) *MeekChannel {
+func NewBrokerChannel(broker string, front string) *BrokerChannel {
 	targetURL, err := url.Parse(broker)
 	if nil != err {
 		return nil
 	}
-	mc := new(MeekChannel)
-	mc.url = targetURL
+	bc := new(BrokerChannel)
+	bc.url = targetURL
 	if "" != front { // Optional front domain.
-		mc.Host = mc.url.Host
-		mc.url.Host = front
+		bc.Host = bc.url.Host
+		bc.url.Host = front
 	}
 
 	// We make a copy of DefaultTransport because we want the default Dial
 	// and TLSHandshakeTimeout settings. But we want to disable the default
 	// ProxyFromEnvironment setting.
-	mc.transport = *http.DefaultTransport.(*http.Transport)
-	mc.transport.Proxy = nil
-	return mc
+	bc.transport = *http.DefaultTransport.(*http.Transport)
+	bc.transport.Proxy = nil
+	return bc
 }
 
 // Roundtrip HTTP POST using WebRTC SessionDescriptions.
 //
-// Sends an SDP offer to the meek broker, which assigns a proxy and responds
+// Send an SDP offer to the broker, which assigns a proxy and responds
 // with an SDP answer from a designated remote WebRTC peer.
-func (mc *MeekChannel) Negotiate(offer *webrtc.SessionDescription) (
+func (bc *BrokerChannel) Negotiate(offer *webrtc.SessionDescription) (
 	*webrtc.SessionDescription, error) {
 	data := bytes.NewReader([]byte(offer.Serialize()))
 	// Suffix with broker's client registration handler.
-	request, err := http.NewRequest("POST", mc.url.String()+"client", data)
+	request, err := http.NewRequest("POST", bc.url.String()+"client", data)
 	if nil != err {
 		return nil, err
 	}
-	if "" != mc.Host { // Set true host if necessary.
-		request.Host = mc.Host
+	if "" != bc.Host { // Set true host if necessary.
+		request.Host = bc.Host
 	}
-	resp, err := mc.transport.RoundTrip(request)
+	resp, err := bc.transport.RoundTrip(request)
 	if nil != err {
 		return nil, err
 	}
 	defer resp.Body.Close()
-	log.Printf("MeekChannel Response:\n%s\n\n", resp.Status)
+	log.Printf("BrokerChannel Response:\n%s\n\n", resp.Status)
 	body, err := ioutil.ReadAll(resp.Body)
 	if nil != err {
 		return nil, err

client/snowflake.go

@@ -1,10 +1,9 @@
-// Client transport plugin for the snowflake pluggable transport.
-//
-// TODO: Use meek for signalling.
+// Client transport plugin for the Snowflake pluggable transport.
 package main
 
 import (
 	"bufio"
+	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -16,10 +15,9 @@ import (
 	"syscall"
 	"time"
 
+	"git.torproject.org/pluggable-transports/goptlib.git"
 	"github.com/keroserene/go-webrtc"
 	"github.com/keroserene/go-webrtc/data"
-
-	"git.torproject.org/pluggable-transports/goptlib.git"
 )
 
 var ptInfo pt.ClientInfo
@@ -93,7 +91,7 @@ func (c *webRTCConn) SetWriteDeadline(t time.Time) error {
 	return fmt.Errorf("SetWriteDeadline not implemented")
 }
 
-func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
+func dialWebRTC(config *webrtc.Configuration, broker *BrokerChannel) (
 	*webRTCConn, error) {
 
 	offerChan := make(chan *webrtc.SessionDescription)
@@ -131,6 +129,8 @@ func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
 		log.Printf("OnIceComplete")
 		offerChan <- pc.LocalDescription()
 	}
+	// This callback is not expected, as the Client initiates the creation
+	// of the data channel, not the remote peer.
 	pc.OnDataChannel = func(channel *data.Channel) {
 		log.Println("OnDataChannel")
 		panic("OnDataChannel")
@@ -151,6 +151,7 @@ func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
 		log.Println("OnClose channel")
 		pw.Close()
 		close(openChan)
+		// TODO: (Issue #12) Should attempt to renegotiate at this point.
 	}
 	dc.OnMessage = func(msg []byte) {
 		log.Printf("OnMessage <--- %d bytes", len(msg))
@@ -173,14 +174,14 @@ func dialWebRTC(config *webrtc.Configuration, meek *MeekChannel) (
 		log.Printf("----------------")
 		go func() {
 			if "" != brokerURL {
-				log.Println("Sending offer via meek channel...\nTarget URL: ", brokerURL,
+				log.Println("Sending offer via BrokerChannel...\nTarget URL: ", brokerURL,
 					"\nFront URL:  ", frontDomain)
-				answer, err := meek.Negotiate(pc.LocalDescription())
+				answer, err := broker.Negotiate(pc.LocalDescription())
 				if nil != err {
-					log.Printf("MeekChannel signaling error: %s", err)
+					log.Printf("BrokerChannel signaling error: %s", err)
 				}
 				if nil == answer {
-					log.Printf("MeekChannel: No answer received.")
+					log.Printf("BrokerChannel: No answer received.")
 				} else {
 					signalChan <- answer
 				}
@@ -236,10 +237,16 @@ func handler(conn *pt.SocksConn) error {
 	}()
 	defer conn.Close()
 
+	// TODO: [#3] Fetch ICE server information from Broker.
+	// TODO: [#18] Consider TURN servers here too.
 	config := webrtc.NewConfiguration(
 		webrtc.OptionIceServer("stun:stun.l.google.com:19302"))
-	meek := NewMeekChannel(brokerURL, frontDomain)
-	remote, err := dialWebRTC(config, meek)
+	broker := NewBrokerChannel(brokerURL, frontDomain)
+	if nil == broker {
+		conn.Reject()
+		return errors.New("Failed to prepare BrokerChannel")
+	}
+	remote, err := dialWebRTC(config, broker)
 	if err != nil {
 		conn.Reject()
 		return err