[snowflake/master] s/MeekChannel/BrokerChannel (close #14) and more informative TODOs - tor-commits

1 Feb 2016

commit 678cf454cd51ab9c749ffd70debaec177e2bed54
Author: Serene Han keroserene+git@gmail.com
Date:   Sun Jan 31 21:42:53 2016 -0800
s/MeekChannel/BrokerChannel (close #14) and more informative TODOs
---
 client/meek-webrtc.go | 74 --------------------------------------------------
 client/rendezvous.go  | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
 client/snowflake.go   | 31 ++++++++++++---------
 3 files changed, 94 insertions(+), 86 deletions(-)

diff --git a/client/meek-webrtc.go b/client/meek-webrtc.go
deleted file mode 100644
index 34ff185..0000000
--- a/client/meek-webrtc.go
+++ /dev/null
@@ -1,74 +0,0 @@
-// Exchange WebRTC SessionDescriptions over a domain-fronted HTTP
-// signaling channel.
-package main
-
-import (
-	"bytes"
-	"io/ioutil"
-	"log"
-	"net/http"
-	"net/url"
-
-	"github.com/keroserene/go-webrtc"
-)
-
-// Meek Signalling Channel.
-type MeekChannel struct {
-	// The Host header to put in the HTTP request (optional and may be
-	// different from the host name in URL).
-	Host      string
-	url       *url.URL
-	transport http.Transport // Used to make all requests.
-}
-
-// Construct a new MeekChannel, 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 {
-	targetURL, err := url.Parse(broker)
-	if nil != err {
-		return nil
-	}
-	mc := new(MeekChannel)
-	mc.url = targetURL
-	if "" != front { // Optional front domain.
-		mc.Host = mc.url.Host
-		mc.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
-}
-
-// Roundtrip HTTP POST using WebRTC SessionDescriptions.
-//
-// Sends an SDP offer to the meek broker, which assigns a proxy and responds
-// with an SDP answer from a designated remote WebRTC peer.
-func (mc *MeekChannel) 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)
-	if nil != err {
-		return nil, err
-	}
-	if "" != mc.Host { // Set true host if necessary.
-		request.Host = mc.Host
-	}
-	resp, err := mc.transport.RoundTrip(request)
-	if nil != err {
-		return nil, err
-	}
-	defer resp.Body.Close()
-	log.Printf("MeekChannel Response:\n%s\n\n", resp.Status)
-	body, err := ioutil.ReadAll(resp.Body)
-	if nil != err {
-		return nil, err
-	}
-	answer := webrtc.DeserializeSessionDescription(string(body))
-	return answer, nil
-}
diff --git a/client/rendezvous.go b/client/rendezvous.go
new file mode 100644
index 0000000..ea0b338
--- /dev/null
+++ b/client/rendezvous.go
@@ -0,0 +1,75 @@
+// 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 (
+	"bytes"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/url"
+
+	"github.com/keroserene/go-webrtc"
+)
+
+// 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
+	url       *url.URL
+	transport http.Transport // Used to make all requests.
+}
+
+// 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 NewBrokerChannel(broker string, front string) *BrokerChannel {
+	targetURL, err := url.Parse(broker)
+	if nil != err {
+		return nil
+	}
+	bc := new(BrokerChannel)
+	bc.url = targetURL
+	if "" != front { // Optional front domain.
+		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.
+	bc.transport = *http.DefaultTransport.(*http.Transport)
+	bc.transport.Proxy = nil
+	return bc
+}
+
+// Roundtrip HTTP POST using WebRTC SessionDescriptions.
+//
+// Send an SDP offer to the broker, which assigns a proxy and responds
+// with an SDP answer from a designated remote WebRTC peer.
+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", bc.url.String()+"client", data)
+	if nil != err {
+		return nil, err
+	}
+	if "" != bc.Host { // Set true host if necessary.
+		request.Host = bc.Host
+	}
+	resp, err := bc.transport.RoundTrip(request)
+	if nil != err {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	log.Printf("BrokerChannel Response:\n%s\n\n", resp.Status)
+	body, err := ioutil.ReadAll(resp.Body)
+	if nil != err {
+		return nil, err
+	}
+	answer := webrtc.DeserializeSessionDescription(string(body))
+	return answer, nil
+}
diff --git a/client/snowflake.go b/client/snowflake.go
index 83179a3..486e602 100644
--- a/client/snowflake.go
+++ b/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

    