Merge pull request #716 from micro/tunnel

Rename Tunnel ID to Channel

network/default.go

@@ -179,10 +179,10 @@ func (n *network) resolve() {
 }
 
 // handleNetConn handles network announcement messages
-func (n *network) handleNetConn(conn tunnel.Conn, msg chan *transport.Message) {
+func (n *network) handleNetConn(sess tunnel.Session, msg chan *transport.Message) {
 	for {
 		m := new(transport.Message)
-		if err := conn.Recv(m); err != nil {
+		if err := sess.Recv(m); err != nil {
 			// TODO: should we bail here?
 			log.Debugf("Network tunnel [%s] receive error: %v", NetworkChannel, err)
 			return
@@ -349,10 +349,10 @@ func (n *network) announce(client transport.Client) {
 }
 
 // handleCtrlConn handles ControlChannel connections
-func (n *network) handleCtrlConn(conn tunnel.Conn, msg chan *transport.Message) {
+func (n *network) handleCtrlConn(sess tunnel.Session, msg chan *transport.Message) {
 	for {
 		m := new(transport.Message)
-		if err := conn.Recv(m); err != nil {
+		if err := sess.Recv(m); err != nil {
 			// TODO: should we bail here?
 			log.Debugf("Network tunnel advert receive error: %v", err)
 			return

tunnel/default.go

@@ -1,9 +1,8 @@
 package tunnel
 
 import (
-	"crypto/sha256"
 	"errors"
-	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -25,7 +24,10 @@ type tun struct {
 
 	sync.RWMutex
 
-	// tunnel token
+	// the unique id for this tunnel
+	id string
+
+	// tunnel token for authentication
 	token string
 
 	// to indicate if we're connected or not
@@ -37,8 +39,8 @@ type tun struct {
 	// close channel
 	closed chan bool
 
-	// a map of sockets based on Micro-Tunnel-Id
-	sockets map[string]*socket
+	// a map of sessions based on Micro-Tunnel-Channel
+	sessions map[string]*session
 
 	// outbound links
 	links map[string]*link
@@ -47,25 +49,6 @@ type tun struct {
 	listener transport.Listener
 }
 
-type link struct {
-	transport.Socket
-	// unique id of this link e.g uuid
-	// which we define for ourselves
-	id string
-	// whether its a loopback connection
-	// this flag is used by the transport listener
-	// which accepts inbound quic connections
-	loopback bool
-	// whether its actually connected
-	// dialled side sets it to connected
-	// after sending the message. the
-	// listener waits for the connect
-	connected bool
-	// the last time we received a keepalive
-	// on this link from the remote side
-	lastKeepAlive time.Time
-}
-
 // create new tunnel on top of a link
 func newTunnel(opts ...Option) *tun {
 	options := DefaultOptions()
@@ -74,12 +57,13 @@ func newTunnel(opts ...Option) *tun {
 	}
 
 	return &tun{
-		options: options,
-		token:   uuid.New().String(),
-		send:    make(chan *message, 128),
-		closed:  make(chan bool),
-		sockets: make(map[string]*socket),
-		links:   make(map[string]*link),
+		options:  options,
+		id:       options.Id,
+		token:    options.Token,
+		send:     make(chan *message, 128),
+		closed:   make(chan bool),
+		sessions: make(map[string]*session),
+		links:    make(map[string]*link),
 	}
 }
 
@@ -93,51 +77,48 @@ func (t *tun) Init(opts ...Option) error {
 	return nil
 }
 
-// getSocket returns a socket from the internal socket map.
-// It does this based on the Micro-Tunnel-Id and Micro-Tunnel-Session
-func (t *tun) getSocket(id, session string) (*socket, bool) {
-	// get the socket
+// getSession returns a session from the internal session map.
+// It does this based on the Micro-Tunnel-Channel and Micro-Tunnel-Session
+func (t *tun) getSession(channel, session string) (*session, bool) {
+	// get the session
 	t.RLock()
-	s, ok := t.sockets[id+session]
+	s, ok := t.sessions[channel+session]
 	t.RUnlock()
 	return s, ok
 }
 
-// newSocket creates a new socket and saves it
-func (t *tun) newSocket(id, session string) (*socket, bool) {
-	// hash the id
-	h := sha256.New()
-	h.Write([]byte(id))
-	id = fmt.Sprintf("%x", h.Sum(nil))
-
-	// new socket
-	s := &socket{
-		id:      id,
-		session: session,
+// newSession creates a new session and saves it
+func (t *tun) newSession(channel, sessionId string) (*session, bool) {
+	// new session
+	s := &session{
+		id:      t.id,
+		channel: channel,
+		session: sessionId,
 		closed:  make(chan bool),
 		recv:    make(chan *message, 128),
 		send:    t.send,
 		wait:    make(chan bool),
+		errChan: make(chan error, 1),
 	}
 
-	// save socket
+	// save session
 	t.Lock()
-	_, ok := t.sockets[id+session]
+	_, ok := t.sessions[channel+sessionId]
 	if ok {
-		// socket already exists
+		// session already exists
 		t.Unlock()
 		return nil, false
 	}
 
-	t.sockets[id+session] = s
+	t.sessions[channel+sessionId] = s
 	t.Unlock()
 
-	// return socket
+	// return session
 	return s, true
 }
 
 // TODO: use tunnel id as part of the session
-func (t *tun) newSession() string {
+func (t *tun) newSessionId() string {
 	return uuid.New().String()
 }
 
@@ -168,10 +149,10 @@ func (t *tun) monitor() {
 	}
 }
 
-// process outgoing messages sent by all local sockets
+// process outgoing messages sent by all local sessions
 func (t *tun) process() {
 	// manage the send buffer
-	// all pseudo sockets throw everything down this
+	// all pseudo sessions throw everything down this
 	for {
 		select {
 		case msg := <-t.send:
@@ -190,6 +171,9 @@ func (t *tun) process() {
 			// set the tunnel id on the outgoing message
 			newMsg.Header["Micro-Tunnel-Id"] = msg.id
 
+			// set the tunnel channel on the outgoing message
+			newMsg.Header["Micro-Tunnel-Channel"] = msg.channel
+
 			// set the session id
 			newMsg.Header["Micro-Tunnel-Session"] = msg.session
 
@@ -203,10 +187,14 @@ func (t *tun) process() {
 				log.Debugf("No links to send to")
 			}
 
+			var sent bool
+			var err error
+
 			for node, link := range t.links {
 				// if the link is not connected skip it
 				if !link.connected {
 					log.Debugf("Link for node %s not connected", node)
+					err = errors.New("link not connected")
 					continue
 				}
 
@@ -214,6 +202,7 @@ func (t *tun) process() {
 				// this is where we explicitly set the link
 				// in a message received via the listen method
 				if len(msg.link) > 0 && link.id != msg.link {
+					err = errors.New("link not found")
 					continue
 				}
 
@@ -221,25 +210,41 @@ func (t *tun) process() {
 				// and the message is being sent outbound via
 				// a dialled connection don't use this link
 				if link.loopback && msg.outbound {
+					err = errors.New("link is loopback")
 					continue
 				}
 
 				// if the message was being returned by the loopback listener
 				// send it back up the loopback link only
 				if msg.loopback && !link.loopback {
+					err = errors.New("link is not loopback")
 					continue
 				}
 
 				// send the message via the current link
 				log.Debugf("Sending %+v to %s", newMsg, node)
-				if err := link.Send(newMsg); err != nil {
-					log.Debugf("Tunnel error sending %+v to %s: %v", newMsg, node, err)
+				if errr := link.Send(newMsg); errr != nil {
+					log.Debugf("Tunnel error sending %+v to %s: %v", newMsg, node, errr)
+					err = errors.New(errr.Error())
 					delete(t.links, node)
 					continue
 				}
+				// is sent
+				sent = true
 			}
 
 			t.Unlock()
+
+			var gerr error
+			if !sent {
+				gerr = err
+			}
+
+			// return error non blocking
+			select {
+			case msg.errChan <- gerr:
+			default:
+			}
 		case <-t.closed:
 			return
 		}
@@ -267,17 +272,23 @@ func (t *tun) listen(link *link) {
 			return
 		}
 
+		// always ensure we have the correct auth token
+		// TODO: segment the tunnel based on token
+		// e.g use it as the basis
+		token := msg.Header["Micro-Tunnel-Token"]
+		if token != t.token {
+			log.Debugf("Tunnel link %s received invalid token %s", token)
+			return
+		}
+
 		switch msg.Header["Micro-Tunnel"] {
 		case "connect":
 			log.Debugf("Tunnel link %s received connect message", link.Remote())
-			// check the Micro-Tunnel-Token
-			token, ok := msg.Header["Micro-Tunnel-Token"]
-			if !ok {
-				continue
-			}
+
+			id := msg.Header["Micro-Tunnel-Id"]
 
 			// are we connecting to ourselves?
-			if token == t.token {
+			if id == t.id {
 				link.loopback = true
 				loopback = true
 			}
@@ -318,76 +329,77 @@ func (t *tun) listen(link *link) {
 			return
 		}
 
-		// strip message header
-		delete(msg.Header, "Micro-Tunnel")
-
 		// the tunnel id
 		id := msg.Header["Micro-Tunnel-Id"]
-		delete(msg.Header, "Micro-Tunnel-Id")
-
+		// the tunnel channel
+		channel := msg.Header["Micro-Tunnel-Channel"]
 		// the session id
-		session := msg.Header["Micro-Tunnel-Session"]
-		delete(msg.Header, "Micro-Tunnel-Session")
+		sessionId := msg.Header["Micro-Tunnel-Session"]
 
-		// strip token header
-		delete(msg.Header, "Micro-Tunnel-Token")
+		// strip tunnel message header
+		for k, _ := range msg.Header {
+			if strings.HasPrefix(k, "Micro-Tunnel") {
+				delete(msg.Header, k)
+			}
+		}
 
 		// if the session id is blank there's nothing we can do
 		// TODO: check this is the case, is there any reason
 		// why we'd have a blank session? Is the tunnel
 		// used for some other purpose?
-		if len(id) == 0 || len(session) == 0 {
+		if len(channel) == 0 || len(sessionId) == 0 {
 			continue
 		}
 
-		var s *socket
+		var s *session
 		var exists bool
 
 		// If its a loopback connection then we've enabled link direction
 		// listening side is used for listening, the dialling side for dialling
 		switch {
 		case loopback:
-			s, exists = t.getSocket(id, "listener")
+			s, exists = t.getSession(channel, "listener")
 		default:
-			// get the socket based on the tunnel id and session
+			// get the session based on the tunnel id and session
 			// this could be something we dialed in which case
 			// we have a session for it otherwise its a listener
-			s, exists = t.getSocket(id, session)
+			s, exists = t.getSession(channel, sessionId)
 			if !exists {
 				// try get it based on just the tunnel id
 				// the assumption here is that a listener
 				// has no session but its set a listener session
-				s, exists = t.getSocket(id, "listener")
+				s, exists = t.getSession(channel, "listener")
 			}
 		}
 
-		// bail if no socket has been found
+		// bail if no session has been found
 		if !exists {
-			log.Debugf("Tunnel skipping no socket exists")
+			log.Debugf("Tunnel skipping no session exists")
 			// drop it, we don't care about
 			// messages we don't know about
 			continue
 		}
-		log.Debugf("Tunnel using socket %s %s", s.id, s.session)
 
-		// is the socket closed?
+		log.Debugf("Tunnel using session %s %s", s.channel, s.session)
+
+		// is the session closed?
 		select {
 		case <-s.closed:
 			// closed
-			delete(t.sockets, id)
+			delete(t.sessions, channel)
 			continue
 		default:
 			// process
 		}
 
-		// is the socket new?
+		// is the session new?
 		select {
-		// if its new the socket is actually blocked waiting
+		// if its new the session is actually blocked waiting
 		// for a connection. so we check if its waiting.
 		case <-s.wait:
 		// if its waiting e.g its new then we close it
 		default:
-			// set remote address of the socket
+			// set remote address of the session
 			s.remote = msg.Header["Remote"]
 			close(s.wait)
 		}
@@ -401,10 +413,12 @@ func (t *tun) listen(link *link) {
 		// construct the internal message
 		imsg := &message{
 			id:       id,
-			session:  session,
+			channel:  channel,
+			session:  sessionId,
 			data:     tmsg,
 			link:     link.id,
 			loopback: loopback,
+			errChan:  make(chan error, 1),
 		}
 
 		// append to recv backlog
@@ -431,6 +445,7 @@ func (t *tun) keepalive(link *link) {
 			if err := link.Send(&transport.Message{
 				Header: map[string]string{
 					"Micro-Tunnel":       "keepalive",
+					"Micro-Tunnel-Id":    t.id,
 					"Micro-Tunnel-Token": t.token,
 				},
 			}); err != nil {
@@ -458,6 +473,7 @@ func (t *tun) setupLink(node string) (*link, error) {
 	if err := c.Send(&transport.Message{
 		Header: map[string]string{
 			"Micro-Tunnel":       "connect",
+			"Micro-Tunnel-Id":    t.id,
 			"Micro-Tunnel-Token": t.token,
 		},
 	}); err != nil {
@@ -568,6 +584,7 @@ func (t *tun) close() error {
 		link.Send(&transport.Message{
 			Header: map[string]string{
 				"Micro-Tunnel":       "close",
+				"Micro-Tunnel-Id":    t.id,
 				"Micro-Tunnel-Token": t.token,
 			},
 		})
@@ -603,10 +620,10 @@ func (t *tun) Close() error {
 	case <-t.closed:
 		return nil
 	default:
-		// close all the sockets
-		for id, s := range t.sockets {
+		// close all the sessions
+		for id, s := range t.sessions {
 			s.Close()
-			delete(t.sockets, id)
+			delete(t.sessions, id)
 		}
 		// close the connection
 		close(t.closed)
@@ -622,52 +639,50 @@ func (t *tun) Close() error {
 }
 
 // Dial an address
-func (t *tun) Dial(addr string) (Conn, error) {
-	log.Debugf("Tunnel dialing %s", addr)
-	c, ok := t.newSocket(addr, t.newSession())
+func (t *tun) Dial(channel string) (Session, error) {
+	log.Debugf("Tunnel dialing %s", channel)
+	c, ok := t.newSession(channel, t.newSessionId())
 	if !ok {
-		return nil, errors.New("error dialing " + addr)
+		return nil, errors.New("error dialing " + channel)
 	}
 	// set remote
-	c.remote = addr
+	c.remote = channel
 	// set local
 	c.local = "local"
-	// outbound socket
+	// outbound session
 	c.outbound = true
 
 	return c, nil
 }
 
 // Accept a connection on the address
-func (t *tun) Listen(addr string) (Listener, error) {
-	log.Debugf("Tunnel listening on %s", addr)
-	// create a new socket by hashing the address
-	c, ok := t.newSocket(addr, "listener")
+func (t *tun) Listen(channel string) (Listener, error) {
+	log.Debugf("Tunnel listening on %s", channel)
+	// create a new session by hashing the address
+	c, ok := t.newSession(channel, "listener")
 	if !ok {
-		return nil, errors.New("already listening on " + addr)
+		return nil, errors.New("already listening on " + channel)
 	}
 
 	// set remote. it will be replaced by the first message received
 	c.remote = "remote"
 	// set local
-	c.local = addr
+	c.local = channel
 
 	tl := &tunListener{
-		addr: addr,
+		channel: channel,
 		// the accept channel
-		accept: make(chan *socket, 128),
+		accept: make(chan *session, 128),
 		// the channel to close
 		closed: make(chan bool),
 		// tunnel closed channel
 		tunClosed: t.closed,
-		// the connection
-		conn: c,
-		// the listener socket
-		socket: c,
+		// the listener session
+		session: c,
 	}
 
 	// this kicks off the internal message processor
-	// for the listener so it can create pseudo sockets
+	// for the listener so it can create pseudo sessions
 	// per session if they do not exist or pass messages
 	// to the existign sessions
 	go tl.process()

tunnel/link.go

@@ -1,10 +1,34 @@
 package tunnel
 
 import (
+	"sync"
+	"time"
+
 	"github.com/google/uuid"
 	"github.com/micro/go-micro/transport"
 )
 
+type link struct {
+	sync.RWMutex
+
+	transport.Socket
+	// unique id of this link e.g uuid
+	// which we define for ourselves
+	id string
+	// whether its a loopback connection
+	// this flag is used by the transport listener
+	// which accepts inbound quic connections
+	loopback bool
+	// whether its actually connected
+	// dialled side sets it to connected
+	// after sending the message. the
+	// listener waits for the connect
+	connected bool
+	// the last time we received a keepalive
+	// on this link from the remote side
+	lastKeepAlive time.Time
+}
+
 func newLink(s transport.Socket) *link {
 	return &link{
 		Socket: s,

tunnel/listener.go

@@ -8,37 +8,37 @@ import (
 
 type tunListener struct {
 	// address of the listener
-	addr string
+	channel string
 	// the accept channel
-	accept chan *socket
+	accept chan *session
 	// the channel to close
 	closed chan bool
 	// the tunnel closed channel
 	tunClosed chan bool
-	// the connection
-	conn Conn
-	// the listener socket
-	socket *socket
+	// the listener session
+	session *session
 }
 
 func (t *tunListener) process() {
 	// our connection map for session
-	conns := make(map[string]*socket)
+	conns := make(map[string]*session)
 
 	for {
 		select {
 		case <-t.closed:
 			return
 		// receive a new message
-		case m := <-t.socket.recv:
-			// get a socket
-			sock, ok := conns[m.session]
+		case m := <-t.session.recv:
+			// get a session
+			sess, ok := conns[m.session]
 			log.Debugf("Tunnel listener received id %s session %s exists: %t", m.id, m.session, ok)
 			if !ok {
-				// create a new socket session
-				sock = &socket{
-					// our tunnel id
+				// create a new session session
+				sess = &session{
+					// the id of the remote side
 					id: m.id,
+					// the channel
+					channel: m.channel,
 					// the session id
 					session: m.session,
 					// is loopback conn
@@ -50,35 +50,37 @@ func (t *tunListener) process() {
 					// recv called by the acceptor
 					recv: make(chan *message, 128),
 					// use the internal send buffer
-					send: t.socket.send,
+					send: t.session.send,
 					// wait
 					wait: make(chan bool),
+					// error channel
+					errChan: make(chan error, 1),
 				}
 
-				// save the socket
-				conns[m.session] = sock
+				// save the session
+				conns[m.session] = sess
 
 				// send to accept chan
 				select {
 				case <-t.closed:
 					return
-				case t.accept <- sock:
+				case t.accept <- sess:
 				}
 			}
 
 			// send this to the accept chan
 			select {
-			case <-sock.closed:
+			case <-sess.closed:
 				delete(conns, m.session)
-			case sock.recv <- m:
+			case sess.recv <- m:
 				log.Debugf("Tunnel listener sent to recv chan id %s session %s", m.id, m.session)
 			}
 		}
 	}
 }
 
-func (t *tunListener) Addr() string {
-	return t.addr
+func (t *tunListener) Channel() string {
+	return t.channel
 }
 
 // Close closes tunnel listener
@@ -93,9 +95,9 @@ func (t *tunListener) Close() error {
 }
 
 // Everytime accept is called we essentially block till we get a new connection
-func (t *tunListener) Accept() (Conn, error) {
+func (t *tunListener) Accept() (Session, error) {
 	select {
-	// if the socket is closed return
+	// if the session is closed return
 	case <-t.closed:
 		return nil, io.EOF
 	case <-t.tunClosed:

tunnel/options.go

@@ -9,6 +9,8 @@ import (
 var (
 	// DefaultAddress is default tunnel bind address
 	DefaultAddress = ":0"
+	// The shared default token
+	DefaultToken = "micro"
 )
 
 type Option func(*Options)
@@ -21,6 +23,8 @@ type Options struct {
 	Address string
 	// Nodes are remote nodes
 	Nodes []string
+	// The shared auth token
+	Token string
 	// Transport listens to incoming connections
 	Transport transport.Transport
 }
@@ -46,6 +50,13 @@ func Nodes(n ...string) Option {
 	}
 }
 
+// Token sets the shared token for auth
+func Token(t string) Option {
+	return func(o *Options) {
+		o.Token = t
+	}
+}
+
 // Transport listens for incoming connections
 func Transport(t transport.Transport) Option {
 	return func(o *Options) {
@@ -58,6 +69,7 @@ func DefaultOptions() Options {
 	return Options{
 		Id:        uuid.New().String(),
 		Address:   DefaultAddress,
+		Token:     DefaultToken,
 		Transport: quic.NewTransport(),
 	}
 }

tunnel/session.go

@@ -2,15 +2,18 @@ package tunnel
 
 import (
 	"errors"
+	"io"
 
 	"github.com/micro/go-micro/transport"
 	"github.com/micro/go-micro/util/log"
 )
 
-// socket is our pseudo socket for transport.Socket
-type socket struct {
-	// socket id based on Micro-Tunnel
+// session is our pseudo session for transport.Socket
+type session struct {
+	// unique id based on the remote tunnel id
 	id string
+	// the channel name
+	channel string
 	// the session id based on Micro.Tunnel-Session
 	session string
 	// closed
@@ -25,12 +28,14 @@ type socket struct {
 	recv chan *message
 	// wait until we have a connection
 	wait chan bool
-	// outbound marks the socket as outbound dialled connection
+	// outbound marks the session as outbound dialled connection
 	outbound bool
-	// lookback marks the socket as a loopback on the inbound
+	// lookback marks the session as a loopback on the inbound
 	loopback bool
 	// the link on which this message was received
 	link string
+	// the error response
+	errChan chan error
 }
 
 // message is sent over the send channel
@@ -39,6 +44,8 @@ type message struct {
 	typ string
 	// tunnel id
 	id string
+	// channel name
+	channel string
 	// the session id
 	session string
 	// outbound marks the message as outbound
@@ -49,28 +56,30 @@ type message struct {
 	link string
 	// transport data
 	data *transport.Message
+	// the error channel
+	errChan chan error
 }
 
-func (s *socket) Remote() string {
+func (s *session) Remote() string {
 	return s.remote
 }
 
-func (s *socket) Local() string {
+func (s *session) Local() string {
 	return s.local
 }
 
-func (s *socket) Id() string {
-	return s.id
-}
-
-func (s *socket) Session() string {
+func (s *session) Id() string {
 	return s.session
 }
 
-func (s *socket) Send(m *transport.Message) error {
+func (s *session) Channel() string {
+	return s.channel
+}
+
+func (s *session) Send(m *transport.Message) error {
 	select {
 	case <-s.closed:
-		return errors.New("socket is closed")
+		return errors.New("session is closed")
 	default:
 		// no op
 	}
@@ -89,28 +98,48 @@ func (s *socket) Send(m *transport.Message) error {
 	msg := &message{
 		typ:      "message",
 		id:       s.id,
+		channel:  s.channel,
 		session:  s.session,
 		outbound: s.outbound,
 		loopback: s.loopback,
 		data:     data,
 		// specify the link on which to send this
-		// it will be blank for dialled sockets
+		// it will be blank for dialled sessions
 		link: s.link,
+		// error chan
+		errChan: s.errChan,
 	}
 	log.Debugf("Appending %+v to send backlog", msg)
 	s.send <- msg
+
+	// wait for an error response
+	select {
+	case err := <-msg.errChan:
+		return err
+	case <-s.closed:
+		return io.EOF
+	}
+
 	return nil
 }
 
-func (s *socket) Recv(m *transport.Message) error {
+func (s *session) Recv(m *transport.Message) error {
 	select {
 	case <-s.closed:
-		return errors.New("socket is closed")
+		return errors.New("session is closed")
 	default:
 		// no op
 	}
 	// recv from backlog
 	msg := <-s.recv
+
+	// check the error if one exists
+	select {
+	case err := <-msg.errChan:
+		return err
+	default:
+	}
+
 	log.Debugf("Received %+v from recv backlog", msg)
 	// set message
 	*m = *msg.data
@@ -118,8 +147,8 @@ func (s *socket) Recv(m *transport.Message) error {
 	return nil
 }
 
-// Close closes the socket
-func (s *socket) Close() error {
+// Close closes the session
+func (s *session) Close() error {
 	select {
 	case <-s.closed:
 		// no op

tunnel/transport/listener.go

@@ -10,7 +10,7 @@ type tunListener struct {
 }
 
 func (t *tunListener) Addr() string {
-	return t.l.Addr()
+	return t.l.Channel()
 }
 
 func (t *tunListener) Close() error {

tunnel/tunnel.go

@@ -17,27 +17,27 @@ type Tunnel interface {
 	Connect() error
 	// Close closes the tunnel
 	Close() error
-	// Dial an endpoint
-	Dial(addr string) (Conn, error)
-	// Accept connections
-	Listen(addr string) (Listener, error)
+	// Connect to a channel
+	Dial(channel string) (Session, error)
+	// Accept connections on a channel
+	Listen(channel string) (Listener, error)
 	// Name of the tunnel implementation
 	String() string
 }
 
 // The listener provides similar constructs to the transport.Listener
 type Listener interface {
-	Addr() string
+	Channel() string
 	Close() error
-	Accept() (Conn, error)
+	Accept() (Session, error)
 }
 
-// Conn is a connection dialed or accepted which includes the tunnel id and session
-type Conn interface {
+// Session is a unique session created when dialling or accepting connections on the tunnel
+type Session interface {
 	// Specifies the tunnel id
 	Id() string
 	// The session
-	Session() string
+	Channel() string
 	// a transport socket
 	transport.Socket
 }