commit c63f5cfc0a391af99cfa52ab90c05b9f0b253854 Author: Serene Han keroserene+git@gmail.com Date: Sat Jun 11 18:24:08 2016 -0700

Separate peers.go file with improved documentation and more solid interfaces --- client/client_test.go | 94 ++++++++++++++++++++++++++++++++++----------------- client/interfaces.go | 28 +++++++++------ client/peers.go | 91 +++++++++++++++++++++++++++++++++++++++++++++++++ client/snowflake.go | 83 ++++----------------------------------------- client/webrtc.go | 10 +++++- 5 files changed, 186 insertions(+), 120 deletions(-)

diff --git a/client/client_test.go b/client/client_test.go index 0bd3844..f58aeb0 100644 --- a/client/client_test.go +++ b/client/client_test.go @@ -9,7 +9,6 @@ import ( "strings" "testing"

- // "git.torproject.org/pluggable-transports/goptlib.git" "github.com/keroserene/go-webrtc" . "github.com/smartystreets/goconvey/convey" ) @@ -24,9 +23,7 @@ func (m *MockDataChannel) Send(data []byte) { m.done <- true }

-func (*MockDataChannel) Close() error { - return nil -} +func (*MockDataChannel) Close() error { return nil }

type MockResponse struct{}

@@ -34,13 +31,9 @@ func (m *MockResponse) Read(p []byte) (int, error) { p = []byte(`{"type":"answer","sdp":"fake"}`) return 0, nil } -func (m *MockResponse) Close() error { - return nil -} +func (m *MockResponse) Close() error { return nil }

-type MockTransport struct { - statusOverride int -} +type MockTransport struct{ statusOverride int }

// Just returns a response with fake SDP answer. func (m *MockTransport) RoundTrip(req *http.Request) (*http.Response, error) { @@ -68,28 +61,17 @@ func (f FakeSocksConn) Reject() error { f.rejected = true return nil } -func (f FakeSocksConn) Grant(addr *net.TCPAddr) error { - return nil -} - -type FakeSnowflakeJar struct { - toRelease *webRTCConn -} +func (f FakeSocksConn) Grant(addr *net.TCPAddr) error { return nil }

-func (f FakeSnowflakeJar) Release() *webRTCConn { - return nil -} +type FakePeers struct{ toRelease *webRTCConn }

-func (f FakeSnowflakeJar) Collect() (*webRTCConn, error) { - return nil, nil -} +func (f FakePeers) Collect() error { return nil } +func (f FakePeers) Pop() *webRTCConn { return nil }

func TestSnowflakeClient(t *testing.T) { - - Convey("WebRTC ConnectLoop", t, func() { - + SkipConvey("WebRTC ConnectLoop", t, func() { Convey("WebRTC ConnectLoop continues until capacity of 1.\n", func() { - snowflakes := NewSnowflakeJar(1) + snowflakes := NewPeers(1) snowflakes.Tongue = FakeDialer{}

go ConnectLoop(snowflakes) @@ -102,7 +84,7 @@ func TestSnowflakeClient(t *testing.T) { })

Convey("WebRTC ConnectLoop continues until capacity of 3.\n", func() { - snowflakes := NewSnowflakeJar(3) + snowflakes := NewPeers(3) snowflakes.Tongue = FakeDialer{}

go ConnectLoop(snowflakes) @@ -115,7 +97,7 @@ func TestSnowflakeClient(t *testing.T) { })

Convey("WebRTC ConnectLoop continues filling when Snowflakes disconnect.\n", func() { - snowflakes := NewSnowflakeJar(3) + snowflakes := NewPeers(3) snowflakes.Tongue = FakeDialer{}

go ConnectLoop(snowflakes) @@ -135,17 +117,67 @@ func TestSnowflakeClient(t *testing.T) { }) })

+ Convey("Peers", t, func() { + Convey("Can construct", func() { + p := NewPeers(1) + So(p.capacity, ShouldEqual, 1) + So(p.current, ShouldEqual, nil) + So(p.snowflakeChan, ShouldNotBeNil) + So(cap(p.snowflakeChan), ShouldEqual, 1) + }) + + Convey("Collecting a Snowflake requires a Tongue.", func() { + p := NewPeers(1) + err := p.Collect() + So(err, ShouldNotBeNil) + So(p.Count(), ShouldEqual, 0) + // Set the dialer so that collection is possible. + p.Tongue = FakeDialer{} + err = p.Collect() + So(err, ShouldBeNil) + So(p.Count(), ShouldEqual, 1) + // S + err = p.Collect() + }) + + Convey("Collection continues until capacity.", func() { + c := 5 + p := NewPeers(c) + p.Tongue = FakeDialer{} + // Fill up to capacity. + for i := 0 ; i < c ; i++ { + fmt.Println("Adding snowflake ", i) + err := p.Collect() + So(err, ShouldBeNil) + So(p.Count(), ShouldEqual, i + 1) + } + // But adding another gives an error. + So(p.Count(), ShouldEqual, c) + err := p.Collect() + So(err, ShouldNotBeNil) + So(p.Count(), ShouldEqual, c) + + // But popping allows it to continue. + s := p.Pop() + So(s, ShouldNotBeNil) + So(p.Count(), ShouldEqual, c) + + // err = p.Collect() + // So(err, ShouldNotBeNil) + // So(p.Count(), ShouldEqual, c) + }) + }) + Convey("Snowflake", t, func() {

SkipConvey("Handler Grants correctly", func() { socks := &FakeSocksConn{} - snowflakes := &FakeSnowflakeJar{} + snowflakes := &FakePeers{}

So(socks.rejected, ShouldEqual, false) snowflakes.toRelease = nil handler(socks, snowflakes) So(socks.rejected, ShouldEqual, true) - })

Convey("WebRTC Connection", func() { diff --git a/client/interfaces.go b/client/interfaces.go index 80a2ba3..ba49a92 100644 --- a/client/interfaces.go +++ b/client/interfaces.go @@ -1,30 +1,36 @@ +// In the Client context, "Snowflake" refers to a remote browser proxy. package main

import ( "net" )

-// Interface for collecting and releasing snowflakes. -type SnowflakeCollector interface { - Collect() (*webRTCConn, error) - Release() *webRTCConn -} - -// Interface for catching those wild Snowflakes. +// Interface for catching Snowflakes. (aka the remote dialer) type Tongue interface { Catch() (*webRTCConn, error) }

-// Interface which primarily adapts to goptlib's SocksConn struct. +// Interface for collecting some number of Snowflakes, for passing along +// ultimately to the SOCKS handler. +type SnowflakeCollector interface { + + // Add a Snowflake to the collection. + // Implementation should decide how to connect and maintain the webRTCConn. + Collect() error + + // Remove and return the most available Snowflake from the collection. + Pop() *webRTCConn +} + +// Interface to adapt to goptlib's SocksConn struct. type SocksConnector interface { Grant(*net.TCPAddr) error Reject() error net.Conn }

-// Interface for the Snowflake's transport. -// (Specifically, webrtc.DataChannel) -type SnowflakeChannel interface { +// Interface for the Snowflake's transport. (Typically just webrtc.DataChannel) +type SnowflakeDataChannel interface { Send([]byte) Close() error } diff --git a/client/peers.go b/client/peers.go new file mode 100644 index 0000000..769174b --- /dev/null +++ b/client/peers.go @@ -0,0 +1,91 @@ +package main + +import ( + "errors" + "fmt" + "log" +) + +// Container which keeps track of multiple WebRTC remote peers. +// Implements |SnowflakeCollector|. +// +// Maintaining a set of pre-connected Peers with fresh but inactive datachannels +// allows allows rapid recovery when the current WebRTC Peer disconnects. +// +// Note: For now, only one remote can be active at any given moment. +// This is a property of Tor circuits & its current multiplexing constraints, +// but could be updated if that changes. +// (Also, this constraint does not necessarily apply to the more generic PT +// version of Snowflake) +type Peers struct { + Tongue + BytesLogger + + snowflakeChan chan *webRTCConn + current *webRTCConn + capacity int + // TODO: Probably not necessary. + maxedChan chan struct{} +} + +// Construct a fresh container of remote peers. +func NewPeers(max int) *Peers { + p := &Peers{capacity: max, current: nil} + // Use buffered go channel to pass new snowflakes onwards to the SOCKS handler. + p.snowflakeChan = make(chan *webRTCConn, max) + p.maxedChan = make(chan struct{}, 1) + return p +} + +// TODO: Needs fixing. +func (p *Peers) Count() int { + count := 0 + if p.current != nil { + count = 1 + } + return count + len(p.snowflakeChan) +} + +// As part of |SnowflakeCollector| interface. +func (p *Peers) Collect() error { + if p.Count() >= p.capacity { + s := fmt.Sprintf("At capacity [%d/%d]", p.Count(), p.capacity) + p.maxedChan <- struct{}{} + return errors.New(s) + } + // Engage the Snowflake Catching interface, which must be available. + if nil == p.Tongue { + return errors.New("Missing Tongue to catch Snowflakes with.") + } + connection, err := p.Tongue.Catch() + if nil == connection || nil != err { + return err + } + // Use the same rate-limited traffic logger to keep consistency. + connection.BytesLogger = p.BytesLogger + p.snowflakeChan <- connection + return nil +} + +// As part of |SnowflakeCollector| interface. +func (p *Peers) Pop() *webRTCConn { + // Blocks until an available snowflake appears. + snowflake, ok := <-p.snowflakeChan + if !ok { + return nil + } + p.current = snowflake + snowflake.BytesLogger = p.BytesLogger + return snowflake +} + +// 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() + } +} diff --git a/client/snowflake.go b/client/snowflake.go index cd7f151..f8edc2a 100644 --- a/client/snowflake.go +++ b/client/snowflake.go @@ -1,12 +1,10 @@ // Client transport plugin for the Snowflake pluggable transport. -// In the Client context, "Snowflake" refers to a remote browser proxy. package main

import ( "bufio" "errors" "flag" - "fmt" "io" "log" "net" @@ -50,81 +48,12 @@ func copyLoop(a, b net.Conn) { log.Println("copy loop ended") }

-// Collect and track available snowflakes. (Implements SnowflakeCollector) -// Right now, it is only possible to use one active remote in a circuit. -// This can be updated once multiplexed transport on a single circuit is available. -// Keeping multiple WebRTC connections available allows for quicker recovery when -// the current snowflake disconnects. -type SnowflakeJar struct { - Tongue - BytesLogger - - snowflakeChan chan *webRTCConn - current *webRTCConn - capacity int - maxedChan chan struct{} -} - -func NewSnowflakeJar(max int) *SnowflakeJar { - p := &SnowflakeJar{capacity: max} - p.snowflakeChan = make(chan *webRTCConn, max) - p.maxedChan = make(chan struct{}, 1) - return p -} - -// Establish connection to some remote WebRTC peer, and keep it available for -// later. -func (jar *SnowflakeJar) Collect() (*webRTCConn, error) { - if jar.Count() >= jar.capacity { - s := fmt.Sprintf("At capacity [%d/%d]", jar.Count(), jar.capacity) - jar.maxedChan <- struct{}{} - return nil, errors.New(s) - } - snowflake, err := jar.Catch() - if err != nil { - return nil, err - } - jar.snowflakeChan <- snowflake - return snowflake, nil -} - -// Prepare and present an available remote WebRTC peer for active use. -func (jar *SnowflakeJar) Release() *webRTCConn { - snowflake, ok := <-jar.snowflakeChan - if !ok { - return nil - } - jar.current = snowflake - snowflake.BytesLogger = jar.BytesLogger - return snowflake -} - -// TODO: Needs fixing. -func (p *SnowflakeJar) Count() int { - count := 0 - if p.current != nil { - count = 1 - } - return count + len(p.snowflakeChan) -} - -// Close all remote peers. -func (p *SnowflakeJar) 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 ConnectLoop(snowflakes SnowflakeCollector) { for { - s, err := snowflakes.Collect() - if nil == s || nil != err { + err := snowflakes.Collect() + if nil != err { log.Println("WebRTC Error:", err, " Retrying in", ReconnectTimeout, "seconds...") // Failed collections get a timeout. @@ -163,8 +92,8 @@ func handler(socks SocksConnector, snowflakes SnowflakeCollector) error { defer func() { handlerChan <- -1 }() - // Wait for an available WebRTC remote... - snowflake := snowflakes.Release() + // Obtain an available WebRTC remote. May block. + snowflake := snowflakes.Pop() if nil == snowflake { socks.Reject() return errors.New("handler: Received invalid Snowflake") @@ -247,10 +176,10 @@ func main() {

// Prepare WebRTC SnowflakeCollector and the Broker, then accumulate connections. // TODO: Expose remote peer capacity as a flag? - snowflakes := NewSnowflakeJar(SnowflakeCapacity) + snowflakes := NewPeers(SnowflakeCapacity)

broker := NewBrokerChannel(brokerURL, frontDomain, CreateBrokerTransport()) - snowflakes.Tongue = WebRTCDialer{broker} + snowflakes.Tongue = NewWebRTCDialer(broker)

// Use a real logger for traffic. snowflakes.BytesLogger = &BytesSyncLogger{ diff --git a/client/webrtc.go b/client/webrtc.go index 41642be..2466a1d 100644 --- a/client/webrtc.go +++ b/client/webrtc.go @@ -14,6 +14,14 @@ import ( // Implements the |Tongue| interface to catch snowflakes, using a BrokerChannel. type WebRTCDialer struct { *BrokerChannel + webrtcConfig *webrtc.Configuration +} + +func NewWebRTCDialer(broker *BrokerChannel) *WebRTCDialer { + return &WebRTCDialer{ + broker, + webrtc.NewConfiguration(iceServers...), + } }

// Initialize a WebRTC Connection by signaling through the broker. @@ -33,7 +41,7 @@ func (w WebRTCDialer) Catch() (*webRTCConn, error) { type webRTCConn struct { config *webrtc.Configuration pc *webrtc.PeerConnection - snowflake SnowflakeChannel // Holds the WebRTC DataChannel. + snowflake SnowflakeDataChannel // Holds the WebRTC DataChannel. broker *BrokerChannel

offerChannel chan *webrtc.SessionDescription