commit 6b8568cc6cf7186d86e844a6f1460c9af802575a
Author: Serene Han <[email protected]>
Date:   Thu May 19 18:06:34 2016 -0700

    client interfaces compose better, remove some globals, test ConnectLoop
---
 client/client_test.go |  85 +++++++++++++++++++++++++-------
 client/snowflake.go   | 133 +++++++++++++++++++++++++++++++++++---------------
 client/webrtc.go      |  43 +++++++++-------
 3 files changed, 186 insertions(+), 75 deletions(-)

diff --git a/client/client_test.go b/client/client_test.go
index 41dc5e6..93e0422 100644
--- a/client/client_test.go
+++ b/client/client_test.go
@@ -2,6 +2,7 @@ package main
 
 import (
        "bytes"
+       "fmt"
        "github.com/keroserene/go-webrtc"
        . "github.com/smartystreets/goconvey/convey"
        "io/ioutil"
@@ -48,9 +49,64 @@ func (m *MockTransport) RoundTrip(req *http.Request) 
(*http.Response, error) {
        return r, nil
 }
 
-func TestConnect(t *testing.T) {
+type FakeDialer struct{}
+
+func (w FakeDialer) Catch() (*webRTCConn, error) {
+       fmt.Println("Caught a dummy snowflake.")
+       return &webRTCConn{}, nil
+}
+
+func TestSnowflakeClient(t *testing.T) {
        Convey("Snowflake", t, func() {
-               webrtcRemotes = make(map[int]*webRTCConn)
+
+               Convey("Peers", func() {
+
+                       Convey("WebRTC ConnectLoop continues until capacity of 
1.\n", func() {
+                               peers := NewPeers(1)
+                               peers.Tongue = FakeDialer{}
+
+                               go ConnectLoop(peers)
+                               <-peers.maxedChan
+
+                               So(peers.Count(), ShouldEqual, 1)
+                               r := <-peers.snowflakeChan
+                               So(r, ShouldNotBeNil)
+                               So(peers.Count(), ShouldEqual, 0)
+                       })
+
+                       Convey("WebRTC ConnectLoop continues until capacity of 
3.\n", func() {
+                               peers := NewPeers(3)
+                               peers.Tongue = FakeDialer{}
+
+                               go ConnectLoop(peers)
+                               <-peers.maxedChan
+                               So(peers.Count(), ShouldEqual, 3)
+                               <-peers.snowflakeChan
+                               <-peers.snowflakeChan
+                               <-peers.snowflakeChan
+                               So(peers.Count(), ShouldEqual, 0)
+                       })
+
+                       Convey("WebRTC ConnectLoop continues filling when 
Snowflakes disconnect.\n", func() {
+                               peers := NewPeers(3)
+                               peers.Tongue = FakeDialer{}
+
+                               go ConnectLoop(peers)
+                               <-peers.maxedChan
+                               So(peers.Count(), ShouldEqual, 3)
+
+                               r := <-peers.snowflakeChan
+                               So(peers.Count(), ShouldEqual, 2)
+                               r.Close()
+                               <-peers.maxedChan
+                               So(peers.Count(), ShouldEqual, 3)
+
+                               <-peers.snowflakeChan
+                               <-peers.snowflakeChan
+                               <-peers.snowflakeChan
+                               So(peers.Count(), ShouldEqual, 0)
+                       })
+               })
 
                Convey("WebRTC Connection", func() {
                        c := new(webRTCConn)
@@ -60,17 +116,13 @@ func TestConnect(t *testing.T) {
                        }
                        So(c.buffer.Bytes(), ShouldEqual, nil)
 
-                       Convey("Create and remove from WebRTCConn set", func() {
-                               So(len(webrtcRemotes), ShouldEqual, 0)
-                               So(remoteIndex, ShouldEqual, 0)
+                       Convey("Can construct a WebRTCConn", func() {
                                s := NewWebRTCConnection(nil, nil)
                                So(s, ShouldNotBeNil)
                                So(s.index, ShouldEqual, 0)
-                               So(len(webrtcRemotes), ShouldEqual, 1)
-                               So(remoteIndex, ShouldEqual, 1)
+                               So(s.offerChannel, ShouldNotBeNil)
+                               So(s.answerChannel, ShouldNotBeNil)
                                s.Close()
-                               So(len(webrtcRemotes), ShouldEqual, 0)
-                               So(remoteIndex, ShouldEqual, 1)
                        })
 
                        Convey("Write buffers when datachannel is nil", func() {
@@ -113,9 +165,6 @@ func TestConnect(t *testing.T) {
                                <-c.reset
                        })
 
-                       Convey("Connect Loop", func() {
-                               // TODO
-                       })
                })
        })
 
@@ -124,14 +173,14 @@ func TestConnect(t *testing.T) {
                transport := &MockTransport{http.StatusOK}
                fakeOffer := webrtc.DeserializeSessionDescription("test")
 
-               Convey("BrokerChannel with no front domain", func() {
+               Convey("Construct BrokerChannel with no front domain", func() {
                        b := NewBrokerChannel("test.broker", "", transport)
                        So(b.url, ShouldNotBeNil)
                        So(b.url.Path, ShouldResemble, "test.broker")
                        So(b.transport, ShouldNotBeNil)
                })
 
-               Convey("BrokerChannel with front domain", func() {
+               Convey("Construct BrokerChannel *with* front domain", func() {
                        b := NewBrokerChannel("test.broker", "front", transport)
                        So(b.url, ShouldNotBeNil)
                        So(b.url.Path, ShouldResemble, "test.broker")
@@ -139,7 +188,7 @@ func TestConnect(t *testing.T) {
                        So(b.transport, ShouldNotBeNil)
                })
 
-               Convey("BrokerChannel Negotiate responds with answer", func() {
+               Convey("BrokerChannel.Negotiate responds with answer", func() {
                        b := NewBrokerChannel("test.broker", "", transport)
                        answer, err := b.Negotiate(fakeOffer)
                        So(err, ShouldBeNil)
@@ -147,7 +196,7 @@ func TestConnect(t *testing.T) {
                        So(answer.Sdp, ShouldResemble, "fake")
                })
 
-               Convey("BrokerChannel Negotiate fails with 503", func() {
+               Convey("BrokerChannel.Negotiate fails with 503", func() {
                        b := NewBrokerChannel("test.broker", "",
                                &MockTransport{http.StatusServiceUnavailable})
                        answer, err := b.Negotiate(fakeOffer)
@@ -156,7 +205,7 @@ func TestConnect(t *testing.T) {
                        So(err.Error(), ShouldResemble, BrokerError503)
                })
 
-               Convey("BrokerChannel Negotiate fails with 400", func() {
+               Convey("BrokerChannel.Negotiate fails with 400", func() {
                        b := NewBrokerChannel("test.broker", "",
                                &MockTransport{http.StatusBadRequest})
                        answer, err := b.Negotiate(fakeOffer)
@@ -165,7 +214,7 @@ func TestConnect(t *testing.T) {
                        So(err.Error(), ShouldResemble, BrokerError400)
                })
 
-               Convey("BrokerChannel Negotiate fails with unexpected", func() {
+               Convey("BrokerChannel.Negotiate fails with unexpected error", 
func() {
                        b := NewBrokerChannel("test.broker", "",
                                &MockTransport{123})
                        answer, err := b.Negotiate(fakeOffer)
diff --git a/client/snowflake.go b/client/snowflake.go
index f32ddc8..61864ca 100644
--- a/client/snowflake.go
+++ b/client/snowflake.go
@@ -5,6 +5,7 @@ import (
        "bufio"
        "errors"
        "flag"
+       "fmt"
        "io"
        "log"
        "net"
@@ -22,14 +23,12 @@ var ptInfo pt.ClientInfo
 
 const (
        ReconnectTimeout  = 10
-       SnowflakeCapacity = 3
+       SnowflakeCapacity = 1
 )
 
 var brokerURL string
 var frontDomain string
 var iceServers IceServerList
-var snowflakeChan = make(chan *webRTCConn, 1)
-var broker *BrokerChannel
 
 // When a connection handler starts, +1 is written to this channel; when it
 // ends, -1 is written.
@@ -50,62 +49,110 @@ func copyLoop(a, b net.Conn) {
        log.Println("copy loop ended")
 }
 
-// Interface that matches both webrtc.DataChannel and for testing.
+// Interface for catching Snowflakes.
+type Tongue interface {
+       Catch() (*webRTCConn, error)
+}
+
+// Interface for the Snowflake transport. (usually a webrtc.DataChannel)
 type SnowflakeChannel interface {
        Send([]byte)
        Close() error
 }
 
+// Collect and track available remote WebRTC Peers, to switch between if the
+// current one disconnects.
+// Right now, it is only possible to use one remote in a circuit. This can be
+// updated once multiplexed transport on a single circuit is available.
+type Peers struct {
+       Tongue
+
+       snowflakeChan chan *webRTCConn
+       current       *webRTCConn
+       capacity      int
+       maxedChan     chan struct{}
+}
+
+func NewPeers(max int) *Peers {
+       p := &Peers{capacity: max}
+       p.snowflakeChan = make(chan *webRTCConn, max)
+       p.maxedChan = make(chan struct{}, 1)
+       return p
+}
+
+// Find, connect, and add a new peer to the internal collection.
+func (p *Peers) FindSnowflake() (*webRTCConn, error) {
+       if p.Count() >= p.capacity {
+               s := fmt.Sprintf("At capacity [%d/%d]", p.Count(), p.capacity)
+               p.maxedChan <- struct{}{}
+               return nil, errors.New(s)
+       }
+       connection, err := p.Catch()
+       if err != nil {
+               return nil, err
+       }
+       return connection, nil
+}
+
+// TODO: Needs fixing.
+func (p *Peers) Count() int {
+       return len(p.snowflakeChan)
+}
+
+// Close all remote peers.
+func (p *Peers) End() {
+       log.Printf("WebRTC: interruped")
+       if nil != p.current {
+               p.current.Close()
+       }
+       for r := range p.snowflakeChan {
+               r.Close()
+       }
+}
+
 // Maintain |SnowflakeCapacity| number of available WebRTC connections, to
 // transfer to the Tor SOCKS handler when needed.
-func SnowflakeConnectLoop() {
-       transport := CreateBrokerTransport()
-       broker = NewBrokerChannel(brokerURL, frontDomain, transport)
+func ConnectLoop(peers *Peers) {
        for {
-               numRemotes := len(webrtcRemotes)
-               if numRemotes >= SnowflakeCapacity {
-                       log.Println("At Capacity: ", numRemotes, "snowflake. 
Re-checking in 10s")
-                       <-time.After(time.Second * 10)
-                       continue
-               }
-               s, err := dialWebRTC()
+               s, err := peers.FindSnowflake()
                if nil == s || nil != err {
-                       log.Println("WebRTC Error: ", err, " retrying...")
+                       log.Println("WebRTC Error:", err,
+                               " Retrying in", ReconnectTimeout, "seconds...")
                        <-time.After(time.Second * ReconnectTimeout)
                        continue
                }
-               snowflakeChan <- s
+               peers.snowflakeChan <- s
+               <-time.After(time.Second)
        }
 }
 
-// Initialize a WebRTC Connection.
-func dialWebRTC() (*webRTCConn, error) {
+// Implements |Tongue|
+type WebRTCDialer struct {
+       *BrokerChannel
+}
+
+// Initialize a WebRTC Connection by signaling through the broker.
+func (w WebRTCDialer) Catch() (*webRTCConn, error) {
+       if nil == w.BrokerChannel {
+               return nil, errors.New("Cannot Dial WebRTC without a 
BrokerChannel.")
+       }
        // TODO: [#3] Fetch ICE server information from Broker.
        // TODO: [#18] Consider TURN servers here too.
        config := webrtc.NewConfiguration(iceServers...)
-       if nil == broker {
-               return nil, errors.New("Failed to prepare BrokerChannel")
-       }
-       connection := NewWebRTCConnection(config, broker)
+       connection := NewWebRTCConnection(config, w.BrokerChannel)
        err := connection.Connect()
        return connection, err
 }
 
-func endWebRTC() {
-       log.Printf("WebRTC: interruped")
-       for _, r := range webrtcRemotes {
-               r.Close()
-       }
-}
-
 // Establish a WebRTC channel for SOCKS connections.
-func handler(conn *pt.SocksConn) error {
+func handler(conn *pt.SocksConn, peers *Peers) error {
        handlerChan <- 1
        defer func() {
                handlerChan <- -1
        }()
        // Wait for an available WebRTC remote...
-       remote, ok := <-snowflakeChan
+       remote, ok := <-peers.snowflakeChan
+       peers.current = remote
        if remote == nil || !ok {
                conn.Reject()
                return errors.New("handler: Received invalid Snowflake")
@@ -125,7 +172,7 @@ func handler(conn *pt.SocksConn) error {
        return nil
 }
 
-func acceptLoop(ln *pt.SocksListener) error {
+func acceptLoop(ln *pt.SocksListener, peers *Peers) error {
        defer ln.Close()
        for {
                log.Println("SOCKS listening...", ln)
@@ -138,7 +185,7 @@ func acceptLoop(ln *pt.SocksListener) error {
                        return err
                }
                go func() {
-                       err := handler(conn)
+                       err := handler(conn, peers)
                        if err != nil {
                                log.Printf("handler error: %s", err)
                        }
@@ -146,6 +193,7 @@ func acceptLoop(ln *pt.SocksListener) error {
        }
 }
 
+// TODO: Fix since multiplexing changes access to remotes.
 func readSignalingMessages(f *os.File) {
        log.Printf("readSignalingMessages")
        s := bufio.NewScanner(f)
@@ -157,10 +205,10 @@ func readSignalingMessages(f *os.File) {
                        log.Printf("ignoring invalid signal message %+q", msg)
                        continue
                }
-               webrtcRemotes[0].answerChannel <- sdp
+               // webrtcRemotes[0].answerChannel <- sdp
        }
        log.Printf("close answerChannel")
-       close(webrtcRemotes[0].answerChannel)
+       // close(webrtcRemotes[0].answerChannel)
        if err := s.Err(); err != nil {
                log.Printf("signal FIFO: %s", err)
        }
@@ -204,8 +252,13 @@ func main() {
                go readSignalingMessages(signalFile)
        }
 
-       webrtcRemotes = make(map[int]*webRTCConn)
-       go SnowflakeConnectLoop()
+       // Prepare WebRTC Peers and the Broker, then accumulate connections.
+       // TODO: Expose remote peer capacity as a flag?
+       remotes := NewPeers(SnowflakeCapacity)
+       broker := NewBrokerChannel(brokerURL, frontDomain, 
CreateBrokerTransport())
+
+       remotes.Tongue = WebRTCDialer{broker}
+       go ConnectLoop(remotes)
 
        ptInfo, err = pt.ClientSetup(nil)
        if err != nil {
@@ -221,12 +274,13 @@ func main() {
        for _, methodName := range ptInfo.MethodNames {
                switch methodName {
                case "snowflake":
+                       // TODO: Be able to recover when SOCKS dies.
                        ln, err := pt.ListenSocks("tcp", "127.0.0.1:0")
                        if err != nil {
                                pt.CmethodError(methodName, err.Error())
                                break
                        }
-                       go acceptLoop(ln)
+                       go acceptLoop(ln, remotes)
                        pt.Cmethod(methodName, ln.Version(), ln.Addr())
                        listeners = append(listeners, ln)
                default:
@@ -234,7 +288,6 @@ func main() {
                }
        }
        pt.CmethodsDone()
-       defer endWebRTC()
 
        var numHandlers int = 0
        var sig os.Signal
@@ -254,6 +307,8 @@ func main() {
                ln.Close()
        }
 
+       remotes.End()
+
        // wait for second signal or no more handlers
        sig = nil
        for sig == nil && numHandlers != 0 {
diff --git a/client/webrtc.go b/client/webrtc.go
index 5b30e95..e01cbf7 100644
--- a/client/webrtc.go
+++ b/client/webrtc.go
@@ -11,26 +11,27 @@ import (
        "time"
 )
 
-// Implements net.Conn interface
+// Remote WebRTC peer.  Implements the |net.Conn| interface.
 type webRTCConn struct {
-       config        *webrtc.Configuration
-       pc            *webrtc.PeerConnection
-       snowflake     SnowflakeChannel // Interface holding the WebRTC 
DataChannel.
-       broker        *BrokerChannel
+       config    *webrtc.Configuration
+       pc        *webrtc.PeerConnection
+       snowflake SnowflakeChannel // Holds the WebRTC DataChannel.
+       broker    *BrokerChannel
+
        offerChannel  chan *webrtc.SessionDescription
        answerChannel chan *webrtc.SessionDescription
        errorChannel  chan error
+       endChannel    chan struct{}
        recvPipe      *io.PipeReader
        writePipe     *io.PipeWriter
        buffer        bytes.Buffer
        reset         chan struct{}
-       index         int
+
+       index  int
+       closed bool
        *BytesInfo
 }
 
-var webrtcRemotes map[int]*webRTCConn
-var remoteIndex int = 0
-
 func (c *webRTCConn) Read(b []byte) (int, error) {
        return c.recvPipe.Read(b)
 }
@@ -51,10 +52,17 @@ func (c *webRTCConn) Close() error {
        var err error = nil
        log.Printf("WebRTC: Closing")
        c.cleanup()
-       close(c.offerChannel)
-       close(c.answerChannel)
-       close(c.errorChannel)
-       delete(webrtcRemotes, c.index)
+       if nil != c.offerChannel {
+               close(c.offerChannel)
+       }
+       if nil != c.answerChannel {
+               close(c.answerChannel)
+       }
+       if nil != c.errorChannel {
+               close(c.errorChannel)
+       }
+       // Mark for deletion.
+       c.closed = true
        return err
 }
 
@@ -78,6 +86,7 @@ func (c *webRTCConn) SetWriteDeadline(t time.Time) error {
        return fmt.Errorf("SetWriteDeadline not implemented")
 }
 
+// Construct a WebRTC PeerConnection.
 func NewWebRTCConnection(config *webrtc.Configuration,
        broker *BrokerChannel) *webRTCConn {
        connection := new(webRTCConn)
@@ -90,6 +99,7 @@ func NewWebRTCConnection(config *webrtc.Configuration,
        connection.errorChannel = make(chan error, 1)
        connection.reset = make(chan struct{}, 1)
 
+       // TODO: Separate out.
        // Log every few seconds.
        connection.BytesInfo = &BytesInfo{
                inboundChan: make(chan int, 5), outboundChan: make(chan int, 5),
@@ -99,9 +109,6 @@ func NewWebRTCConnection(config *webrtc.Configuration,
 
        // Pipes remain the same even when DataChannel gets switched.
        connection.recvPipe, connection.writePipe = io.Pipe()
-       connection.index = remoteIndex
-       webrtcRemotes[connection.index] = connection
-       remoteIndex++
        return connection
 }
 
@@ -296,12 +303,12 @@ func (c *webRTCConn) Reset() {
 
 func (c *webRTCConn) cleanup() {
        if nil != c.snowflake {
-               s := c.snowflake
                log.Printf("WebRTC: closing DataChannel")
+               dataChannel := c.snowflake
                // Setting snowflake to nil *before* Close indicates to OnClose 
that it
                // was locally triggered.
                c.snowflake = nil
-               s.Close()
+               dataChannel.Close()
        }
        if nil != c.pc {
                log.Printf("WebRTC: closing PeerConnection")

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