Add separate client for dynamic relays (fixes #2368)

Did some manual tests in the playground, such as kicking off two clients in parallel, first connecting,
second one getting a message about already being connected, falling back to the second address.

lib/relay/client/client.go

@@ -5,279 +5,37 @@ package client
 import (
 	"crypto/tls"
 	"fmt"
-	"net"
 	"net/url"
 	"time"
 
-	"github.com/syncthing/syncthing/lib/dialer"
-	syncthingprotocol "github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/relay/protocol"
-	"github.com/syncthing/syncthing/lib/sync"
 )
 
-type ProtocolClient struct {
-	URI         *url.URL
-	Invitations chan protocol.SessionInvitation
+type relayClientFactory func(uri *url.URL, certs []tls.Certificate, invitations chan protocol.SessionInvitation) RelayClient
 
-	closeInvitationsOnFinish bool
-
-	config *tls.Config
-
-	timeout time.Duration
-
-	stop    chan struct{}
-	stopped chan struct{}
-
-	conn *tls.Conn
-
-	mut       sync.RWMutex
-	connected bool
-	latency   time.Duration
-}
-
-func NewProtocolClient(uri *url.URL, certs []tls.Certificate, invitations chan protocol.SessionInvitation) *ProtocolClient {
-	closeInvitationsOnFinish := false
-	if invitations == nil {
-		closeInvitationsOnFinish = true
-		invitations = make(chan protocol.SessionInvitation)
-	}
-
-	return &ProtocolClient{
-		URI:         uri,
-		Invitations: invitations,
-
-		closeInvitationsOnFinish: closeInvitationsOnFinish,
-
-		config: configForCerts(certs),
-
-		timeout: time.Minute * 2,
-
-		stop:    make(chan struct{}),
-		stopped: make(chan struct{}),
-
-		mut:       sync.NewRWMutex(),
-		connected: false,
-	}
-}
-
-func (c *ProtocolClient) Serve() {
-	c.stop = make(chan struct{})
-	c.stopped = make(chan struct{})
-	defer close(c.stopped)
-
-	if err := c.connect(); err != nil {
-		l.Debugln("Relay connect:", err)
-		return
-	}
-
-	l.Debugln(c, "connected", c.conn.RemoteAddr())
-
-	if err := c.join(); err != nil {
-		c.conn.Close()
-		l.Infoln("Relay join:", err)
-		return
-	}
-
-	if err := c.conn.SetDeadline(time.Time{}); err != nil {
-		c.conn.Close()
-		l.Infoln("Relay set deadline:", err)
-		return
-	}
-
-	l.Debugln(c, "joined", c.conn.RemoteAddr(), "via", c.conn.LocalAddr())
-
-	defer c.cleanup()
-	c.mut.Lock()
-	c.connected = true
-	c.mut.Unlock()
-
-	messages := make(chan interface{})
-	errors := make(chan error, 1)
-
-	go messageReader(c.conn, messages, errors)
-
-	timeout := time.NewTimer(c.timeout)
-
-	for {
-		select {
-		case message := <-messages:
-			timeout.Reset(c.timeout)
-			l.Debugf("%s received message %T", c, message)
-
-			switch msg := message.(type) {
-			case protocol.Ping:
-				if err := protocol.WriteMessage(c.conn, protocol.Pong{}); err != nil {
-					l.Infoln("Relay write:", err)
-					return
-
-				}
-				l.Debugln(c, "sent pong")
-
-			case protocol.SessionInvitation:
-				ip := net.IP(msg.Address)
-				if len(ip) == 0 || ip.IsUnspecified() {
-					msg.Address = c.conn.RemoteAddr().(*net.TCPAddr).IP[:]
-				}
-				c.Invitations <- msg
-
-			default:
-				l.Infoln("Relay: protocol error: unexpected message %v", msg)
-				return
-			}
-
-		case <-c.stop:
-			l.Debugln(c, "stopping")
-			return
-
-		case err := <-errors:
-			l.Infoln("Relay received:", err)
-			return
-
-		case <-timeout.C:
-			l.Debugln(c, "timed out")
-			return
-		}
-	}
-}
-
-func (c *ProtocolClient) Stop() {
-	if c.stop == nil {
-		return
-	}
-
-	close(c.stop)
-	<-c.stopped
-}
-
-func (c *ProtocolClient) StatusOK() bool {
-	c.mut.RLock()
-	con := c.connected
-	c.mut.RUnlock()
-	return con
-}
-
-func (c *ProtocolClient) Latency() time.Duration {
-	c.mut.RLock()
-	lat := c.latency
-	c.mut.RUnlock()
-	return lat
-}
-
-func (c *ProtocolClient) String() string {
-	return fmt.Sprintf("ProtocolClient@%p", c)
-}
-
-func (c *ProtocolClient) connect() error {
-	if c.URI.Scheme != "relay" {
-		return fmt.Errorf("Unsupported relay schema: %v", c.URI.Scheme)
-	}
-
-	t0 := time.Now()
-	tcpConn, err := dialer.Dial("tcp", c.URI.Host)
-	if err != nil {
-		return err
-	}
-
-	c.mut.Lock()
-	c.latency = time.Since(t0)
-	c.mut.Unlock()
-
-	conn := tls.Client(tcpConn, c.config)
-	if err = conn.Handshake(); err != nil {
-		return err
-	}
-
-	if err := conn.SetDeadline(time.Now().Add(10 * time.Second)); err != nil {
-		conn.Close()
-		return err
-	}
-
-	if err := performHandshakeAndValidation(conn, c.URI); err != nil {
-		conn.Close()
-		return err
-	}
-
-	c.conn = conn
-	return nil
-}
-
-func (c *ProtocolClient) cleanup() {
-	if c.closeInvitationsOnFinish {
-		close(c.Invitations)
-		c.Invitations = make(chan protocol.SessionInvitation)
-	}
-
-	l.Debugln(c, "cleaning up")
-
-	c.mut.Lock()
-	c.connected = false
-	c.mut.Unlock()
-
-	c.conn.Close()
-}
-
-func (c *ProtocolClient) join() error {
-	if err := protocol.WriteMessage(c.conn, protocol.JoinRelayRequest{}); err != nil {
-		return err
-	}
-
-	message, err := protocol.ReadMessage(c.conn)
-	if err != nil {
-		return err
-	}
-
-	switch msg := message.(type) {
-	case protocol.Response:
-		if msg.Code != 0 {
-			return fmt.Errorf("Incorrect response code %d: %s", msg.Code, msg.Message)
-		}
-
-	default:
-		return fmt.Errorf("protocol error: expecting response got %v", msg)
+var (
+	supportedSchemes = map[string]relayClientFactory{
+		"relay":         newStaticClient,
+		"dynamic+http":  newDynamicClient,
+		"dynamic+https": newDynamicClient,
 	}
+)
 
-	return nil
+type RelayClient interface {
+	Serve()
+	Stop()
+	StatusOK() bool
+	Latency() time.Duration
+	String() string
+	Invitations() chan protocol.SessionInvitation
+	URI() *url.URL
 }
 
-func performHandshakeAndValidation(conn *tls.Conn, uri *url.URL) error {
-	if err := conn.Handshake(); err != nil {
-		return err
-	}
-
-	cs := conn.ConnectionState()
-	if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != protocol.ProtocolName {
-		return fmt.Errorf("protocol negotiation error")
-	}
-
-	q := uri.Query()
-	relayIDs := q.Get("id")
-	if relayIDs != "" {
-		relayID, err := syncthingprotocol.DeviceIDFromString(relayIDs)
-		if err != nil {
-			return fmt.Errorf("relay address contains invalid verification id: %s", err)
-		}
-
-		certs := cs.PeerCertificates
-		if cl := len(certs); cl != 1 {
-			return fmt.Errorf("unexpected certificate count: %d", cl)
-		}
-
-		remoteID := syncthingprotocol.NewDeviceID(certs[0].Raw)
-		if remoteID != relayID {
-			return fmt.Errorf("relay id does not match. Expected %v got %v", relayID, remoteID)
-		}
+func NewClient(uri *url.URL, certs []tls.Certificate, invitations chan protocol.SessionInvitation) (RelayClient, error) {
+	factory, ok := supportedSchemes[uri.Scheme]
+	if !ok {
+		return nil, fmt.Errorf("Unsupported scheme: %s", uri.Scheme)
 	}
 
-	return nil
-}
-
-func messageReader(conn net.Conn, messages chan<- interface{}, errors chan<- error) {
-	for {
-		msg, err := protocol.ReadMessage(conn)
-		if err != nil {
-			errors <- err
-			return
-		}
-		messages <- msg
-	}
+	return factory(uri, certs, invitations), nil
 }

lib/relay/client/dynamic.go

@@ -0,0 +1,217 @@
+// Copyright (C) 2015 Audrius Butkevicius and Contributors (see the CONTRIBUTORS file).
+
+package client
+
+import (
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"sort"
+	"time"
+
+	"github.com/syncthing/syncthing/lib/osutil"
+	"github.com/syncthing/syncthing/lib/relay/protocol"
+	"github.com/syncthing/syncthing/lib/sync"
+)
+
+type dynamicClient struct {
+	pooladdr                 *url.URL
+	certs                    []tls.Certificate
+	invitations              chan protocol.SessionInvitation
+	closeInvitationsOnFinish bool
+
+	mut    sync.RWMutex
+	client RelayClient
+	stop   chan struct{}
+}
+
+func newDynamicClient(uri *url.URL, certs []tls.Certificate, invitations chan protocol.SessionInvitation) RelayClient {
+	closeInvitationsOnFinish := false
+	if invitations == nil {
+		closeInvitationsOnFinish = true
+		invitations = make(chan protocol.SessionInvitation)
+	}
+	return &dynamicClient{
+		pooladdr:                 uri,
+		certs:                    certs,
+		invitations:              invitations,
+		closeInvitationsOnFinish: closeInvitationsOnFinish,
+
+		mut: sync.NewRWMutex(),
+	}
+}
+
+func (c *dynamicClient) Serve() {
+	c.mut.Lock()
+	c.stop = make(chan struct{})
+	c.mut.Unlock()
+
+	uri := *c.pooladdr
+
+	// Trim off the `dynamic+` prefix
+	uri.Scheme = uri.Scheme[8:]
+
+	l.Debugln(c, "looking up dynamic relays")
+
+	data, err := http.Get(uri.String())
+	if err != nil {
+		l.Debugln(c, "failed to lookup dynamic relays", err)
+		return
+	}
+
+	var ann dynamicAnnouncement
+	err = json.NewDecoder(data.Body).Decode(&ann)
+	data.Body.Close()
+	if err != nil {
+		l.Debugln(c, "failed to lookup dynamic relays", err)
+		return
+	}
+
+	defer c.cleanup()
+
+	var addrs []string
+	for _, relayAnn := range ann.Relays {
+		ruri, err := url.Parse(relayAnn.URL)
+		if err != nil {
+			l.Debugln(c, "failed to parse dynamic relay address", relayAnn.URL, err)
+			continue
+		}
+		l.Debugln(c, "found", ruri)
+		addrs = append(addrs, ruri.String())
+	}
+
+	for _, addr := range relayAddressesSortedByLatency(addrs) {
+		select {
+		case <-c.stop:
+			l.Debugln(c, "stopping")
+			return
+		default:
+			ruri, err := url.Parse(addr)
+			if err != nil {
+				l.Debugln(c, "skipping relay", addr, err)
+				continue
+			}
+			client, err := NewClient(ruri, c.certs, c.invitations)
+			if err != nil {
+				continue
+			}
+			c.mut.Lock()
+			c.client = client
+			c.mut.Unlock()
+
+			c.client.Serve()
+
+			c.mut.Lock()
+			c.client = nil
+			c.mut.Unlock()
+		}
+	}
+	l.Debugln(c, "could not find a connectable relay")
+}
+
+func (c *dynamicClient) Stop() {
+	c.mut.RLock()
+	defer c.mut.RUnlock()
+	close(c.stop)
+	if c.client == nil {
+		return
+	}
+	c.client.Stop()
+}
+
+func (c *dynamicClient) StatusOK() bool {
+	c.mut.RLock()
+	defer c.mut.RUnlock()
+	if c.client == nil {
+		return false
+	}
+	return c.client.StatusOK()
+}
+
+func (c *dynamicClient) Latency() time.Duration {
+	c.mut.RLock()
+	defer c.mut.RUnlock()
+	if c.client == nil {
+		return time.Hour
+	}
+	return c.client.Latency()
+}
+
+func (c *dynamicClient) String() string {
+	return fmt.Sprintf("DynamicClient:%p:%s@%s", c, c.URI(), c.pooladdr)
+}
+
+func (c *dynamicClient) URI() *url.URL {
+	c.mut.RLock()
+	defer c.mut.RUnlock()
+	if c.client == nil {
+		return c.pooladdr
+	}
+	return c.client.URI()
+}
+
+func (c *dynamicClient) Invitations() chan protocol.SessionInvitation {
+	c.mut.RLock()
+	inv := c.invitations
+	c.mut.RUnlock()
+	return inv
+}
+
+func (c *dynamicClient) cleanup() {
+	c.mut.Lock()
+	if c.closeInvitationsOnFinish {
+		close(c.invitations)
+		c.invitations = make(chan protocol.SessionInvitation)
+	}
+	c.mut.Unlock()
+}
+
+// This is the announcement recieved from the relay server;
+// {"relays": [{"url": "relay://10.20.30.40:5060"}, ...]}
+type dynamicAnnouncement struct {
+	Relays []struct {
+		URL string
+	}
+}
+
+// relayAddressesSortedByLatency adds local latency to the relay, and sorts them
+// by sum latency, and returns the addresses.
+func relayAddressesSortedByLatency(input []string) []string {
+	relays := make(relayList, len(input))
+	for i, relay := range input {
+		if latency, err := osutil.GetLatencyForURL(relay); err == nil {
+			relays[i] = relayWithLatency{relay, int(latency / time.Millisecond)}
+		} else {
+			relays[i] = relayWithLatency{relay, int(time.Hour / time.Millisecond)}
+		}
+	}
+
+	sort.Sort(relays)
+
+	addresses := make([]string, len(relays))
+	for i, relay := range relays {
+		addresses[i] = relay.relay
+	}
+	return addresses
+}
+
+type relayWithLatency struct {
+	relay   string
+	latency int
+}
+
+type relayList []relayWithLatency
+
+func (l relayList) Len() int {
+	return len(l)
+}
+
+func (l relayList) Less(a, b int) bool {
+	return l[a].latency < l[b].latency
+}
+
+func (l relayList) Swap(a, b int) {
+	l[a], l[b] = l[b], l[a]
+}

lib/relay/client/methods.go

@@ -102,7 +102,11 @@ func JoinSession(invitation protocol.SessionInvitation) (net.Conn, error) {
 func TestRelay(uri *url.URL, certs []tls.Certificate, sleep time.Duration, times int) bool {
 	id := syncthingprotocol.NewDeviceID(certs[0].Certificate[0])
 	invs := make(chan protocol.SessionInvitation, 1)
-	c := NewProtocolClient(uri, certs, invs)
+	c, err := NewClient(uri, certs, invs)
+	if err != nil {
+		close(invs)
+		return false
+	}
 	go c.Serve()
 	defer func() {
 		close(invs)

lib/relay/client/static.go

@@ -0,0 +1,291 @@
+// Copyright (C) 2015 Audrius Butkevicius and Contributors (see the CONTRIBUTORS file).
+
+package client
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net"
+	"net/url"
+	"time"
+
+	syncthingprotocol "github.com/syncthing/syncthing/lib/protocol"
+	"github.com/syncthing/syncthing/lib/relay/protocol"
+	"github.com/syncthing/syncthing/lib/sync"
+)
+
+type staticClient struct {
+	uri         *url.URL
+	invitations chan protocol.SessionInvitation
+
+	closeInvitationsOnFinish bool
+
+	config *tls.Config
+
+	timeout time.Duration
+
+	stop    chan struct{}
+	stopped chan struct{}
+
+	conn *tls.Conn
+
+	mut       sync.RWMutex
+	connected bool
+	latency   time.Duration
+}
+
+func newStaticClient(uri *url.URL, certs []tls.Certificate, invitations chan protocol.SessionInvitation) RelayClient {
+	closeInvitationsOnFinish := false
+	if invitations == nil {
+		closeInvitationsOnFinish = true
+		invitations = make(chan protocol.SessionInvitation)
+	}
+
+	return &staticClient{
+		uri:         uri,
+		invitations: invitations,
+
+		closeInvitationsOnFinish: closeInvitationsOnFinish,
+
+		config: configForCerts(certs),
+
+		timeout: time.Minute * 2,
+
+		stop:    make(chan struct{}),
+		stopped: make(chan struct{}),
+
+		mut:       sync.NewRWMutex(),
+		connected: false,
+	}
+}
+
+func (c *staticClient) Serve() {
+	c.stop = make(chan struct{})
+	c.stopped = make(chan struct{})
+	defer close(c.stopped)
+
+	if err := c.connect(); err != nil {
+		l.Debugln("Relay connect:", err)
+		return
+	}
+
+	l.Debugln(c, "connected", c.conn.RemoteAddr())
+
+	if err := c.join(); err != nil {
+		c.conn.Close()
+		l.Infoln("Relay join:", err)
+		return
+	}
+
+	if err := c.conn.SetDeadline(time.Time{}); err != nil {
+		c.conn.Close()
+		l.Infoln("Relay set deadline:", err)
+		return
+	}
+
+	l.Debugln(c, "joined", c.conn.RemoteAddr(), "via", c.conn.LocalAddr())
+
+	defer c.cleanup()
+	c.mut.Lock()
+	c.connected = true
+	c.mut.Unlock()
+
+	messages := make(chan interface{})
+	errors := make(chan error, 1)
+
+	go messageReader(c.conn, messages, errors)
+
+	timeout := time.NewTimer(c.timeout)
+
+	for {
+		select {
+		case message := <-messages:
+			timeout.Reset(c.timeout)
+			l.Debugf("%s received message %T", c, message)
+
+			switch msg := message.(type) {
+			case protocol.Ping:
+				if err := protocol.WriteMessage(c.conn, protocol.Pong{}); err != nil {
+					l.Infoln("Relay write:", err)
+					return
+
+				}
+				l.Debugln(c, "sent pong")
+
+			case protocol.SessionInvitation:
+				ip := net.IP(msg.Address)
+				if len(ip) == 0 || ip.IsUnspecified() {
+					msg.Address = c.conn.RemoteAddr().(*net.TCPAddr).IP[:]
+				}
+				c.invitations <- msg
+
+			default:
+				l.Infoln("Relay: protocol error: unexpected message %v", msg)
+				return
+			}
+
+		case <-c.stop:
+			l.Debugln(c, "stopping")
+			return
+
+		case err := <-errors:
+			l.Infoln("Relay received:", err)
+			return
+
+		case <-timeout.C:
+			l.Debugln(c, "timed out")
+			return
+		}
+	}
+}
+
+func (c *staticClient) Stop() {
+	if c.stop == nil {
+		return
+	}
+
+	close(c.stop)
+	<-c.stopped
+}
+
+func (c *staticClient) StatusOK() bool {
+	c.mut.RLock()
+	con := c.connected
+	c.mut.RUnlock()
+	return con
+}
+
+func (c *staticClient) Latency() time.Duration {
+	c.mut.RLock()
+	lat := c.latency
+	c.mut.RUnlock()
+	return lat
+}
+
+func (c *staticClient) String() string {
+	return fmt.Sprintf("StaticClient:%p@%s", c, c.URI())
+}
+
+func (c *staticClient) URI() *url.URL {
+	return c.uri
+}
+
+func (c *staticClient) Invitations() chan protocol.SessionInvitation {
+	c.mut.RLock()
+	inv := c.invitations
+	c.mut.RUnlock()
+	return inv
+}
+
+func (c *staticClient) connect() error {
+	if c.uri.Scheme != "relay" {
+		return fmt.Errorf("Unsupported relay schema: %v", c.uri.Scheme)
+	}
+
+	t0 := time.Now()
+	tcpConn, err := net.Dial("tcp", c.uri.Host)
+	if err != nil {
+		return err
+	}
+
+	c.mut.Lock()
+	c.latency = time.Since(t0)
+	c.mut.Unlock()
+
+	conn := tls.Client(tcpConn, c.config)
+	if err = conn.Handshake(); err != nil {
+		return err
+	}
+
+	if err := conn.SetDeadline(time.Now().Add(10 * time.Second)); err != nil {
+		conn.Close()
+		return err
+	}
+
+	if err := performHandshakeAndValidation(conn, c.uri); err != nil {
+		conn.Close()
+		return err
+	}
+
+	c.conn = conn
+	return nil
+}
+
+func (c *staticClient) cleanup() {
+	l.Debugln(c, "cleaning up")
+	c.mut.Lock()
+	if c.closeInvitationsOnFinish {
+		close(c.invitations)
+		c.invitations = make(chan protocol.SessionInvitation)
+	}
+	c.connected = false
+	c.mut.Unlock()
+
+	c.conn.Close()
+}
+
+func (c *staticClient) join() error {
+	if err := protocol.WriteMessage(c.conn, protocol.JoinRelayRequest{}); err != nil {
+		return err
+	}
+
+	message, err := protocol.ReadMessage(c.conn)
+	if err != nil {
+		return err
+	}
+
+	switch msg := message.(type) {
+	case protocol.Response:
+		if msg.Code != 0 {
+			return fmt.Errorf("Incorrect response code %d: %s", msg.Code, msg.Message)
+		}
+
+	default:
+		return fmt.Errorf("protocol error: expecting response got %v", msg)
+	}
+
+	return nil
+}
+
+func performHandshakeAndValidation(conn *tls.Conn, uri *url.URL) error {
+	if err := conn.Handshake(); err != nil {
+		return err
+	}
+
+	cs := conn.ConnectionState()
+	if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != protocol.ProtocolName {
+		return fmt.Errorf("protocol negotiation error")
+	}
+
+	q := uri.Query()
+	relayIDs := q.Get("id")
+	if relayIDs != "" {
+		relayID, err := syncthingprotocol.DeviceIDFromString(relayIDs)
+		if err != nil {
+			return fmt.Errorf("relay address contains invalid verification id: %s", err)
+		}
+
+		certs := cs.PeerCertificates
+		if cl := len(certs); cl != 1 {
+			return fmt.Errorf("unexpected certificate count: %d", cl)
+		}
+
+		remoteID := syncthingprotocol.NewDeviceID(certs[0].Raw)
+		if remoteID != relayID {
+			return fmt.Errorf("relay id does not match. Expected %v got %v", relayID, remoteID)
+		}
+	}
+
+	return nil
+}
+
+func messageReader(conn net.Conn, messages chan<- interface{}, errors chan<- error) {
+	for {
+		msg, err := protocol.ReadMessage(conn)
+		if err != nil {
+			errors <- err
+			return
+		}
+		messages <- msg
+	}
+}

lib/relay/relay.go

@@ -8,15 +8,13 @@ package relay
 
 import (
 	"crypto/tls"
-	"encoding/json"
-	"net/http"
+
 	"net/url"
 	"sort"
 	"time"
 
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/events"
-	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/relay/client"
 	"github.com/syncthing/syncthing/lib/relay/protocol"
 	"github.com/syncthing/syncthing/lib/sync"
@@ -34,7 +32,7 @@ type Svc struct {
 	tlsCfg *tls.Config
 
 	tokens      map[string]suture.ServiceToken
-	clients     map[string]*client.ProtocolClient
+	clients     map[string]client.RelayClient
 	mut         sync.RWMutex
 	invitations chan protocol.SessionInvitation
 	conns       chan *tls.Conn
@@ -56,7 +54,7 @@ func NewSvc(cfg *config.Wrapper, tlsCfg *tls.Config) *Svc {
 		tlsCfg: tlsCfg,
 
 		tokens:      make(map[string]suture.ServiceToken),
-		clients:     make(map[string]*client.ProtocolClient),
+		clients:     make(map[string]client.RelayClient),
 		mut:         sync.NewRWMutex(),
 		invitations: make(chan protocol.SessionInvitation),
 		conns:       conns,
@@ -106,61 +104,17 @@ func (s *Svc) CommitConfiguration(from, to config.Configuration) bool {
 		existing[uri.String()] = uri
 	}
 
-	// Query dynamic addresses, and pick the closest relay from the ones they provide.
-	for key, uri := range existing {
-		if uri.Scheme != "dynamic+http" && uri.Scheme != "dynamic+https" {
-			continue
-		}
-		delete(existing, key)
-
-		// Trim off the `dynamic+` prefix
-		uri.Scheme = uri.Scheme[8:]
-
-		l.Debugln("Looking up dynamic relays from", uri)
-
-		data, err := http.Get(uri.String())
-		if err != nil {
-			l.Debugln("Failed to lookup dynamic relays", err)
-			continue
-		}
-
-		var ann dynamicAnnouncement
-		err = json.NewDecoder(data.Body).Decode(&ann)
-		data.Body.Close()
-		if err != nil {
-			l.Debugln("Failed to lookup dynamic relays", err)
-			continue
-		}
-
-		var dynRelayAddrs []string
-		for _, relayAnn := range ann.Relays {
-			ruri, err := url.Parse(relayAnn.URL)
-			if err != nil {
-				l.Debugln("Failed to parse dynamic relay address", relayAnn.URL, err)
-				continue
-			}
-			l.Debugln("Found", ruri, "via", uri)
-			dynRelayAddrs = append(dynRelayAddrs, ruri.String())
-		}
-
-		if len(dynRelayAddrs) > 0 {
-			dynRelayAddrs = relayAddressesSortedByLatency(dynRelayAddrs)
-			closestRelay := dynRelayAddrs[0]
-			l.Debugln("Picking", closestRelay, "as closest dynamic relay from", uri)
-			ruri, _ := url.Parse(closestRelay)
-			existing[closestRelay] = ruri
-		} else {
-			l.Debugln("No dynamic relay found on", uri)
-		}
-	}
-
 	s.mut.Lock()
 
 	for key, uri := range existing {
 		_, ok := s.tokens[key]
 		if !ok {
 			l.Debugln("Connecting to relay", uri)
-			c := client.NewProtocolClient(uri, s.tlsCfg.Certificates, s.invitations)
+			c, err := client.NewClient(uri, s.tlsCfg.Certificates, s.invitations)
+			if err != nil {
+				l.Debugln("Failed to connect to relay", uri, err)
+				continue
+			}
 			s.tokens[key] = s.Add(c)
 			s.clients[key] = c
 		}
@@ -197,8 +151,8 @@ func (s *Svc) Relays() []string {
 
 	s.mut.RLock()
 	relays := make([]string, 0, len(s.clients))
-	for uri := range s.clients {
-		relays = append(relays, uri)
+	for _, client := range s.clients {
+		relays = append(relays, client.URI().String())
 	}
 	s.mut.RUnlock()
 
@@ -216,14 +170,14 @@ func (s *Svc) RelayStatus(uri string) (time.Duration, bool) {
 	}
 
 	s.mut.RLock()
-	client, ok := s.clients[uri]
-	s.mut.RUnlock()
-
-	if !ok || !client.StatusOK() {
-		return time.Hour, false
+	for _, client := range s.clients {
+		if client.URI().String() == uri {
+			return client.Latency(), client.StatusOK()
+		}
 	}
+	s.mut.RUnlock()
 
-	return client.Latency(), true
+	return time.Hour, false
 }
 
 // Accept returns a new *tls.Conn. The connection is already handshaken.
@@ -277,7 +231,7 @@ func (r *invitationReceiver) Stop() {
 // The eventBroadcaster sends a RelayStateChanged event when the relay status
 // changes. We need this somewhat ugly polling mechanism as there's currently
 // no way to get the event feed directly from the relay lib. This may be
-// somethign to revisit later, possibly.
+// something to revisit later, possibly.
 type eventBroadcaster struct {
 	svc  *Svc
 	stop chan struct{}
@@ -322,51 +276,3 @@ func (e *eventBroadcaster) Serve() {
 func (e *eventBroadcaster) Stop() {
 	close(e.stop)
 }
-
-// This is the announcement recieved from the relay server;
-// {"relays": [{"url": "relay://10.20.30.40:5060"}, ...]}
-type dynamicAnnouncement struct {
-	Relays []struct {
-		URL string
-	}
-}
-
-// relayAddressesSortedByLatency adds local latency to the relay, and sorts them
-// by sum latency, and returns the addresses.
-func relayAddressesSortedByLatency(input []string) []string {
-	relays := make(relayList, len(input))
-	for i, relay := range input {
-		if latency, err := osutil.GetLatencyForURL(relay); err == nil {
-			relays[i] = relayWithLatency{relay, int(latency / time.Millisecond)}
-		} else {
-			relays[i] = relayWithLatency{relay, int(time.Hour / time.Millisecond)}
-		}
-	}
-
-	sort.Sort(relays)
-
-	addresses := make([]string, len(relays))
-	for i, relay := range relays {
-		addresses[i] = relay.relay
-	}
-	return addresses
-}
-
-type relayWithLatency struct {
-	relay   string
-	latency int
-}
-
-type relayList []relayWithLatency
-
-func (l relayList) Len() int {
-	return len(l)
-}
-
-func (l relayList) Less(a, b int) bool {
-	return l[a].latency < l[b].latency
-}
-
-func (l relayList) Swap(a, b int) {
-	l[a], l[b] = l[b], l[a]
-}