network: rework discoverer/server interaction

* treat connected/handshaked peers separately in the discoverer, save
   "original" address for connected ones, it can be a name instead of IP and
   it's important to keep it to avoid reconnections
 * store name->IP mapping for seeds if and when they're connected to avoid
   reconnections
 * block seed if it's detected to be our own node (which is often the case for
   small private networks)
 * add an event for handshaked peers in the server, connected but
   non-handshaked ones are not really helpful for MinPeers or GetAddr logic

Fixes #2796.

pkg/network/discovery.go

@@ -22,10 +22,10 @@ type Discoverer interface {
 	NetworkSize() int
 	PoolCount() int
 	RequestRemote(int)
-	RegisterBadAddr(string)
+	RegisterSelf(AddressablePeer)
-	RegisterGoodAddr(string, capability.Capabilities)
+	RegisterGood(AddressablePeer)
-	RegisterConnectedAddr(string)
+	RegisterConnected(AddressablePeer)
-	UnregisterConnectedAddr(string)
+	UnregisterConnected(AddressablePeer, bool)
 	UnconnectedPeers() []string
 	BadPeers() []string
 	GoodPeers() []AddressWithCapabilities
@@ -39,12 +39,13 @@ type AddressWithCapabilities struct {
 
 // DefaultDiscovery default implementation of the Discoverer interface.
 type DefaultDiscovery struct {
-	seeds            []string
+	seeds            map[string]string
 	transport        Transporter
 	lock             sync.RWMutex
 	dialTimeout      time.Duration
 	badAddrs         map[string]bool
 	connectedAddrs   map[string]bool
+	handshakedAddrs  map[string]bool
 	goodAddrs        map[string]capability.Capabilities
 	unconnectedAddrs map[string]int
 	attempted        map[string]bool
@@ -55,12 +56,17 @@ type DefaultDiscovery struct {
 
 // NewDefaultDiscovery returns a new DefaultDiscovery.
 func NewDefaultDiscovery(addrs []string, dt time.Duration, ts Transporter) *DefaultDiscovery {
+	var seeds = make(map[string]string)
+	for i := range addrs {
+		seeds[addrs[i]] = ""
+	}
 	d := &DefaultDiscovery{
-		seeds:            addrs,
+		seeds:            seeds,
 		transport:        ts,
 		dialTimeout:      dt,
 		badAddrs:         make(map[string]bool),
 		connectedAddrs:   make(map[string]bool),
+		handshakedAddrs:  make(map[string]bool),
 		goodAddrs:        make(map[string]capability.Capabilities),
 		unconnectedAddrs: make(map[string]int),
 		attempted:        make(map[string]bool),
@@ -83,7 +89,7 @@ func (d *DefaultDiscovery) BackFill(addrs ...string) {
 
 func (d *DefaultDiscovery) backfill(addrs ...string) {
 	for _, addr := range addrs {
-		if d.badAddrs[addr] || d.connectedAddrs[addr] ||
+		if d.badAddrs[addr] || d.connectedAddrs[addr] || d.handshakedAddrs[addr] ||
 			d.unconnectedAddrs[addr] > 0 {
 			continue
 		}
@@ -117,7 +123,7 @@ func (d *DefaultDiscovery) RequestRemote(requested int) {
 		var nextAddr string
 		d.lock.Lock()
 		for addr := range d.unconnectedAddrs {
-			if !d.connectedAddrs[addr] && !d.attempted[addr] {
+			if !d.connectedAddrs[addr] && !d.handshakedAddrs[addr] && !d.attempted[addr] {
 				nextAddr = addr
 				break
 			}
@@ -125,8 +131,8 @@ func (d *DefaultDiscovery) RequestRemote(requested int) {
 
 		if nextAddr == "" {
 			// Empty pool, try seeds.
-			for _, addr := range d.seeds {
+			for addr, ip := range d.seeds {
-				if !d.connectedAddrs[addr] && !d.attempted[addr] {
+				if ip == "" && !d.attempted[addr] {
 					nextAddr = addr
 					break
 				}
@@ -144,26 +150,33 @@ func (d *DefaultDiscovery) RequestRemote(requested int) {
 	}
 }
 
-// RegisterBadAddr registers the given address as a bad address.
+// RegisterSelf registers the given Peer as a bad one, because it's our own node.
-func (d *DefaultDiscovery) RegisterBadAddr(addr string) {
+func (d *DefaultDiscovery) RegisterSelf(p AddressablePeer) {
-	var isSeed bool
+	var connaddr = p.ConnectionAddr()
 	d.lock.Lock()
-	for _, seed := range d.seeds {
+	delete(d.connectedAddrs, connaddr)
-		if addr == seed {
+	d.registerBad(connaddr, true)
-			isSeed = true
+	d.registerBad(p.PeerAddr().String(), true)
-			break
+	d.lock.Unlock()
+}
+
+func (d *DefaultDiscovery) registerBad(addr string, force bool) {
+	_, isSeed := d.seeds[addr]
+	if isSeed {
+		if !force {
+			d.seeds[addr] = ""
+		} else {
+			d.seeds[addr] = "forever" // That's our own address, so never try connecting to it.
 		}
-	}
+	} else {
-	if !isSeed {
 		d.unconnectedAddrs[addr]--
-		if d.unconnectedAddrs[addr] <= 0 {
+		if d.unconnectedAddrs[addr] <= 0 || force {
 			d.badAddrs[addr] = true
 			delete(d.unconnectedAddrs, addr)
 			delete(d.goodAddrs, addr)
 		}
 	}
 	d.updateNetSize()
-	d.lock.Unlock()
 }
 
 // UnconnectedPeers returns all addresses of unconnected addrs.
@@ -203,31 +216,53 @@ func (d *DefaultDiscovery) GoodPeers() []AddressWithCapabilities {
 	return addrs
 }
 
-// RegisterGoodAddr registers a known good connected address that has passed
+// RegisterGood registers a known good connected peer that has passed
 // handshake successfully.
-func (d *DefaultDiscovery) RegisterGoodAddr(s string, c capability.Capabilities) {
+func (d *DefaultDiscovery) RegisterGood(p AddressablePeer) {
+	var s = p.PeerAddr().String()
 	d.lock.Lock()
-	d.goodAddrs[s] = c
+	d.handshakedAddrs[s] = true
+	d.goodAddrs[s] = p.Version().Capabilities
 	delete(d.badAddrs, s)
 	d.lock.Unlock()
 }
 
-// UnregisterConnectedAddr tells the discoverer that this address is no longer
+// UnregisterConnected tells the discoverer that this peer is no longer
 // connected, but it is still considered a good one.
-func (d *DefaultDiscovery) UnregisterConnectedAddr(s string) {
+func (d *DefaultDiscovery) UnregisterConnected(p AddressablePeer, duplicate bool) {
+	var (
+		peeraddr = p.PeerAddr().String()
+		connaddr = p.ConnectionAddr()
+	)
 	d.lock.Lock()
-	delete(d.connectedAddrs, s)
+	delete(d.connectedAddrs, connaddr)
-	d.backfill(s)
+	if !duplicate {
+		for addr, ip := range d.seeds {
+			if ip == peeraddr {
+				d.seeds[addr] = ""
+				break
+			}
+		}
+		delete(d.handshakedAddrs, peeraddr)
+		if _, ok := d.goodAddrs[peeraddr]; ok {
+			d.backfill(peeraddr)
+		}
+	}
 	d.lock.Unlock()
 }
 
-// RegisterConnectedAddr tells discoverer that the given address is now connected.
+// RegisterConnected tells discoverer that the given peer is now connected.
-func (d *DefaultDiscovery) RegisterConnectedAddr(addr string) {
+func (d *DefaultDiscovery) RegisterConnected(p AddressablePeer) {
+	var addr = p.ConnectionAddr()
 	d.lock.Lock()
+	d.registerConnected(addr)
+	d.lock.Unlock()
+}
+
+func (d *DefaultDiscovery) registerConnected(addr string) {
 	delete(d.unconnectedAddrs, addr)
 	d.connectedAddrs[addr] = true
 	d.updateNetSize()
-	d.lock.Unlock()
 }
 
 // GetFanOut returns the optimal number of nodes to broadcast packets to.
@@ -242,9 +277,9 @@ func (d *DefaultDiscovery) NetworkSize() int {
 
 // updateNetSize updates network size estimation metric. Must be called under read lock.
 func (d *DefaultDiscovery) updateNetSize() {
-	var netsize = len(d.connectedAddrs) + len(d.unconnectedAddrs) + 1 // 1 for the node itself.
+	var netsize = len(d.handshakedAddrs) + len(d.unconnectedAddrs) + 1 // 1 for the node itself.
-	var fanOut = 2.5 * math.Log(float64(netsize-1))                   // -1 for the number of potential peers.
+	var fanOut = 2.5 * math.Log(float64(netsize-1))                    // -1 for the number of potential peers.
-	if netsize == 2 {                                                 // log(1) == 0.
+	if netsize == 2 {                                                  // log(1) == 0.
 		fanOut = 1 // But we still want to push messages to the peer.
 	}
 
@@ -255,12 +290,19 @@ func (d *DefaultDiscovery) updateNetSize() {
 }
 
 func (d *DefaultDiscovery) tryAddress(addr string) {
-	err := d.transport.Dial(addr, d.dialTimeout)
+	p, err := d.transport.Dial(addr, d.dialTimeout)
 	d.lock.Lock()
 	delete(d.attempted, addr)
+	if err == nil {
+		if _, ok := d.seeds[addr]; ok {
+			d.seeds[addr] = p.PeerAddr().String()
+		}
+		d.registerConnected(addr)
+	} else {
+		d.registerBad(addr, false)
+	}
 	d.lock.Unlock()
 	if err != nil {
-		d.RegisterBadAddr(addr)
 		time.Sleep(d.dialTimeout)
 		d.RequestRemote(1)
 	}

pkg/network/discovery_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/nspcc-dev/neo-go/pkg/network/capability"
+	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	atomic2 "go.uber.org/atomic"
@@ -22,18 +23,40 @@ type fakeTransp struct {
 	addr     string
 }
 
+type fakeAPeer struct {
+	addr    string
+	peer    string
+	version *payload.Version
+}
+
+func (f *fakeAPeer) ConnectionAddr() string {
+	return f.addr
+}
+
+func (f *fakeAPeer) PeerAddr() net.Addr {
+	tcpAddr, err := net.ResolveTCPAddr("tcp", f.peer)
+	if err != nil {
+		panic(err)
+	}
+	return tcpAddr
+}
+
+func (f *fakeAPeer) Version() *payload.Version {
+	return f.version
+}
+
 func newFakeTransp(s *Server) Transporter {
 	return &fakeTransp{}
 }
 
-func (ft *fakeTransp) Dial(addr string, timeout time.Duration) error {
+func (ft *fakeTransp) Dial(addr string, timeout time.Duration) (AddressablePeer, error) {
 	var ret error
 	if atomic.LoadInt32(&ft.retFalse) > 0 {
 		ret = errors.New("smth bad happened")
 	}
 	ft.dialCh <- addr
 
-	return ret
+	return &fakeAPeer{addr: addr, peer: addr}, ret
 }
 func (ft *fakeTransp) Accept() {
 	if ft.started.Load() {
@@ -83,7 +106,7 @@ func TestDefaultDiscoverer(t *testing.T) {
 		select {
 		case a := <-ts.dialCh:
 			dialled = append(dialled, a)
-			d.RegisterConnectedAddr(a)
+			d.RegisterConnected(&fakeAPeer{addr: a, peer: a})
 		case <-time.After(time.Second):
 			t.Fatalf("timeout expecting for transport dial")
 		}
@@ -97,10 +120,14 @@ func TestDefaultDiscoverer(t *testing.T) {
 
 	// Registered good addresses should end up in appropriate set.
 	for _, addr := range set1 {
-		d.RegisterGoodAddr(addr, capability.Capabilities{
+		d.RegisterGood(&fakeAPeer{
-			{
+			addr: addr,
-				Type: capability.FullNode,
+			peer: addr,
-				Data: &capability.Node{StartHeight: 123},
+			version: &payload.Version{
+				Capabilities: capability.Capabilities{{
+					Type: capability.FullNode,
+					Data: &capability.Node{StartHeight: 123},
+				}},
 			},
 		})
 	}
@@ -130,7 +157,7 @@ func TestDefaultDiscoverer(t *testing.T) {
 
 	// Unregistering connected should work.
 	for _, addr := range set1 {
-		d.UnregisterConnectedAddr(addr)
+		d.UnregisterConnected(&fakeAPeer{addr: addr, peer: addr}, false)
 	}
 	assert.Equal(t, 2, len(d.UnconnectedPeers())) // They're re-added automatically.
 	assert.Equal(t, 0, len(d.BadPeers()))

pkg/network/helper_test.go

@@ -13,7 +13,6 @@ import (
 	"github.com/nspcc-dev/neo-go/internal/fakechain"
 	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/io"
-	"github.com/nspcc-dev/neo-go/pkg/network/capability"
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/zap/zaptest"
@@ -35,10 +34,10 @@ func (d *testDiscovery) BackFill(addrs ...string) {
 	d.backfill = append(d.backfill, addrs...)
 }
 func (d *testDiscovery) PoolCount() int { return 0 }
-func (d *testDiscovery) RegisterBadAddr(addr string) {
+func (d *testDiscovery) RegisterSelf(p AddressablePeer) {
 	d.Lock()
 	defer d.Unlock()
-	d.bad = append(d.bad, addr)
+	d.bad = append(d.bad, p.ConnectionAddr())
 }
 func (d *testDiscovery) GetFanOut() int {
 	d.Lock()
@@ -50,16 +49,16 @@ func (d *testDiscovery) NetworkSize() int {
 	defer d.Unlock()
 	return len(d.connected) + len(d.backfill)
 }
-func (d *testDiscovery) RegisterGoodAddr(string, capability.Capabilities) {}
+func (d *testDiscovery) RegisterGood(AddressablePeer) {}
-func (d *testDiscovery) RegisterConnectedAddr(addr string) {
+func (d *testDiscovery) RegisterConnected(p AddressablePeer) {
 	d.Lock()
 	defer d.Unlock()
-	d.connected = append(d.connected, addr)
+	d.connected = append(d.connected, p.ConnectionAddr())
 }
-func (d *testDiscovery) UnregisterConnectedAddr(addr string) {
+func (d *testDiscovery) UnregisterConnected(p AddressablePeer, force bool) {
 	d.Lock()
 	defer d.Unlock()
-	d.unregistered = append(d.unregistered, addr)
+	d.unregistered = append(d.unregistered, p.ConnectionAddr())
 }
 func (d *testDiscovery) UnconnectedPeers() []string {
 	d.Lock()
@@ -100,6 +99,9 @@ func newLocalPeer(t *testing.T, s *Server) *localPeer {
 	}
 }
 
+func (p *localPeer) ConnectionAddr() string {
+	return p.netaddr.String()
+}
 func (p *localPeer) RemoteAddr() net.Addr {
 	return &p.netaddr
 }

pkg/network/peer.go

@@ -7,10 +7,12 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 )
 
-// Peer represents a network node neo-go is connected to.
+type AddressablePeer interface {
-type Peer interface {
+	// ConnectionAddr returns an address-like identifier of this connection
-	// RemoteAddr returns the remote address that we're connected to now.
+	// before we have a proper one (after the handshake). It's either the
-	RemoteAddr() net.Addr
+	// address from discoverer (if initiated from node) or one from socket
+	// (if connected to node from outside).
+	ConnectionAddr() string
 	// PeerAddr returns the remote address that should be used to establish
 	// a new connection to the node. It can differ from the RemoteAddr
 	// address in case the remote node is a client and its current
@@ -18,6 +20,16 @@ type Peer interface {
 	// to connect to it. It's only valid after the handshake is completed.
 	// Before that, it returns the same address as RemoteAddr.
 	PeerAddr() net.Addr
+	// Version returns peer's version message if the peer has handshaked
+	// already.
+	Version() *payload.Version
+}
+
+// Peer represents a network node neo-go is connected to.
+type Peer interface {
+	AddressablePeer
+	// RemoteAddr returns the remote address that we're connected to now.
+	RemoteAddr() net.Addr
 	Disconnect(error)
 
 	// BroadcastPacket is a context-bound packet enqueuer, it either puts the
@@ -49,7 +61,6 @@ type Peer interface {
 	// EnqueueHPPacket is similar to EnqueueHPMessage, but accepts a slice of
 	// message(s) bytes.
 	EnqueueHPPacket([]byte) error
-	Version() *payload.Version
 	LastBlockIndex() uint32
 	Handshaked() bool
 	IsFullNode() bool

pkg/network/server.go

@@ -127,6 +127,7 @@ type (
 
 		register   chan Peer
 		unregister chan peerDrop
+		handshake  chan Peer
 		quit       chan struct{}
 		relayFin   chan struct{}
 
@@ -181,6 +182,7 @@ func newServerFromConstructors(config ServerConfig, chain Ledger, stSync StateSy
 		relayFin:       make(chan struct{}),
 		register:       make(chan Peer),
 		unregister:     make(chan peerDrop),
+		handshake:      make(chan Peer),
 		txInMap:        make(map[util.Uint256]struct{}),
 		peers:          make(map[Peer]bool),
 		syncReached:    atomic.NewBool(false),
@@ -462,31 +464,10 @@ func (s *Server) run() {
 					zap.Stringer("addr", drop.peer.RemoteAddr()),
 					zap.Error(drop.reason),
 					zap.Int("peerCount", s.PeerCount()))
-				addr := drop.peer.PeerAddr().String()
 				if errors.Is(drop.reason, errIdenticalID) {
-					s.discovery.RegisterBadAddr(addr)
+					s.discovery.RegisterSelf(drop.peer)
-				} else if errors.Is(drop.reason, errAlreadyConnected) {
-					// There is a race condition when peer can be disconnected twice for the this reason
-					// which can lead to no connections to peer at all. Here we check for such a possibility.
-					stillConnected := false
-					s.lock.RLock()
-					verDrop := drop.peer.Version()
-					addr := drop.peer.PeerAddr().String()
-					if verDrop != nil {
-						for peer := range s.peers {
-							ver := peer.Version()
-							// Already connected, drop this connection.
-							if ver != nil && ver.Nonce == verDrop.Nonce && peer.PeerAddr().String() == addr {
-								stillConnected = true
-							}
-						}
-					}
-					s.lock.RUnlock()
-					if !stillConnected {
-						s.discovery.UnregisterConnectedAddr(addr)
-					}
 				} else {
-					s.discovery.UnregisterConnectedAddr(addr)
+					s.discovery.UnregisterConnected(drop.peer, errors.Is(drop.reason, errAlreadyConnected))
 				}
 				updatePeersConnectedMetric(s.PeerCount())
 			} else {
@@ -494,6 +475,19 @@ func (s *Server) run() {
 				// because we have two goroutines sending signals here
 				s.lock.Unlock()
 			}
+
+		case p := <-s.handshake:
+			ver := p.Version()
+			s.log.Info("started protocol",
+				zap.Stringer("addr", p.RemoteAddr()),
+				zap.ByteString("userAgent", ver.UserAgent),
+				zap.Uint32("startHeight", p.LastBlockIndex()),
+				zap.Uint32("id", ver.Nonce))
+
+			s.discovery.RegisterGood(p)
+
+			s.tryInitStateSync()
+			s.tryStartServices()
 		}
 	}
 }
@@ -700,7 +694,6 @@ func (s *Server) handleVersionCmd(p Peer, version *payload.Version) error {
 		}
 	}
 	s.lock.RUnlock()
-	s.discovery.RegisterConnectedAddr(peerAddr)
 	return p.SendVersionAck(NewMessage(CMDVerack, payload.NewNullPayload()))
 }
 
@@ -1356,9 +1349,6 @@ func (s *Server) handleMessage(peer Peer, msg *Message) error {
 				return err
 			}
 			go peer.StartProtocol()
-
-			s.tryInitStateSync()
-			s.tryStartServices()
 		default:
 			return fmt.Errorf("received '%s' during handshake", msg.Command.String())
 		}

pkg/network/server_test.go

@@ -141,14 +141,17 @@ func TestServerRegisterPeer(t *testing.T) {
 	for i := range ps {
 		ps[i] = newLocalPeer(t, s)
 		ps[i].netaddr.Port = i + 1
+		ps[i].version = &payload.Version{Nonce: uint32(i), UserAgent: []byte("fake")}
 	}
 
 	startWithCleanup(t, s)
 
 	s.register <- ps[0]
 	require.Eventually(t, func() bool { return 1 == s.PeerCount() }, time.Second, time.Millisecond*10)
+	s.handshake <- ps[0]
 
 	s.register <- ps[1]
+	s.handshake <- ps[1]
 	require.Eventually(t, func() bool { return 2 == s.PeerCount() }, time.Second, time.Millisecond*10)
 
 	require.Equal(t, 0, len(s.discovery.UnconnectedPeers()))

pkg/network/tcp_peer.go

@@ -13,7 +13,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/network/capability"
 	"github.com/nspcc-dev/neo-go/pkg/network/payload"
 	"go.uber.org/atomic"
-	"go.uber.org/zap"
 )
 
 type handShakeStage uint8
@@ -48,6 +47,8 @@ type TCPPeer struct {
 	version *payload.Version
 	// Index of the last block.
 	lastBlockIndex uint32
+	// pre-handshake non-canonical connection address.
+	addr string
 
 	lock       sync.RWMutex
 	finale     sync.Once
@@ -69,10 +70,11 @@ type TCPPeer struct {
 }
 
 // NewTCPPeer returns a TCPPeer structure based on the given connection.
-func NewTCPPeer(conn net.Conn, s *Server) *TCPPeer {
+func NewTCPPeer(conn net.Conn, addr string, s *Server) *TCPPeer {
 	return &TCPPeer{
 		conn:     conn,
 		server:   s,
+		addr:     addr,
 		done:     make(chan struct{}),
 		sendQ:    make(chan []byte, requestQueueSize),
 		p2pSendQ: make(chan []byte, p2pMsgQueueSize),
@@ -256,13 +258,8 @@ func (p *TCPPeer) handleQueues() {
 func (p *TCPPeer) StartProtocol() {
 	var err error
 
-	p.server.log.Info("started protocol",
+	p.server.handshake <- p
-		zap.Stringer("addr", p.RemoteAddr()),
-		zap.ByteString("userAgent", p.Version().UserAgent),
-		zap.Uint32("startHeight", p.lastBlockIndex),
-		zap.Uint32("id", p.Version().Nonce))
 
-	p.server.discovery.RegisterGoodAddr(p.PeerAddr().String(), p.version.Capabilities)
 	err = p.server.requestBlocksOrHeaders(p)
 	if err != nil {
 		p.Disconnect(err)
@@ -384,6 +381,14 @@ func (p *TCPPeer) HandleVersionAck() error {
 	return nil
 }
 
+// ConnectionAddr implements the Peer interface.
+func (p *TCPPeer) ConnectionAddr() string {
+	if p.addr != "" {
+		return p.addr
+	}
+	return p.conn.RemoteAddr().String()
+}
+
 // RemoteAddr implements the Peer interface.
 func (p *TCPPeer) RemoteAddr() net.Addr {
 	return p.conn.RemoteAddr()

pkg/network/tcp_peer_test.go

@@ -18,8 +18,8 @@ func connReadStub(conn net.Conn) {
 func TestPeerHandshake(t *testing.T) {
 	server, client := net.Pipe()
 
-	tcpS := NewTCPPeer(server, newTestServer(t, ServerConfig{}))
+	tcpS := NewTCPPeer(server, "", newTestServer(t, ServerConfig{}))
-	tcpC := NewTCPPeer(client, newTestServer(t, ServerConfig{}))
+	tcpC := NewTCPPeer(client, "", newTestServer(t, ServerConfig{}))
 
 	// Something should read things written into the pipe.
 	go connReadStub(tcpS.conn)

pkg/network/tcp_transport.go

@@ -30,14 +30,14 @@ func NewTCPTransport(s *Server, bindAddr string, log *zap.Logger) *TCPTransport
 }
 
 // Dial implements the Transporter interface.
-func (t *TCPTransport) Dial(addr string, timeout time.Duration) error {
+func (t *TCPTransport) Dial(addr string, timeout time.Duration) (AddressablePeer, error) {
 	conn, err := net.DialTimeout("tcp", addr, timeout)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	p := NewTCPPeer(conn, t.server)
+	p := NewTCPPeer(conn, addr, t.server)
 	go p.handleConn()
-	return nil
+	return p, nil
 }
 
 // Accept implements the Transporter interface.
@@ -69,7 +69,7 @@ func (t *TCPTransport) Accept() {
 			t.log.Warn("TCP accept error", zap.Error(err))
 			continue
 		}
-		p := NewTCPPeer(conn, t.server)
+		p := NewTCPPeer(conn, "", t.server)
 		go p.handleConn()
 	}
 }

pkg/network/transport.go

@@ -5,7 +5,7 @@ import "time"
 // Transporter is an interface that allows us to abstract
 // any form of communication between the server and its peers.
 type Transporter interface {
-	Dial(addr string, timeout time.Duration) error
+	Dial(addr string, timeout time.Duration) (AddressablePeer, error)
 	Accept()
 	Proto() string
 	Address() string