Merge pull request #551 from jbenet/fix-swarm-more-connect

p2p/net/swarm: more connection bugs

net/swarm/dial_test.go

+package swarm
+
+import (
+	"net"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	addrutil "github.com/jbenet/go-ipfs/p2p/net/swarm/addr"
+	peer "github.com/jbenet/go-ipfs/p2p/peer"
+	testutil "github.com/jbenet/go-ipfs/util/testutil"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+	ma "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr"
+	manet "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr-net"
+)
+
+func acceptAndHang(l net.Listener) {
+	conns := make([]net.Conn, 0, 10)
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			break
+		}
+		if c != nil {
+			conns = append(conns, c)
+		}
+	}
+	for _, c := range conns {
+		c.Close()
+	}
+}
+
+func TestSimultDials(t *testing.T) {
+	// t.Skip("skipping for another test")
+	t.Parallel()
+
+	ctx := context.Background()
+	swarms := makeSwarms(ctx, t, 2)
+
+	// connect everyone
+	{
+		var wg sync.WaitGroup
+		connect := func(s *Swarm, dst peer.ID, addr ma.Multiaddr) {
+			// copy for other peer
+			log.Debugf("TestSimultOpen: connecting: %s --> %s (%s)", s.local, dst, addr)
+			s.peers.AddAddress(dst, addr)
+			if _, err := s.Dial(ctx, dst); err != nil {
+				t.Fatal("error swarm dialing to peer", err)
+			}
+			wg.Done()
+		}
+
+		ifaceAddrs0, err := swarms[0].InterfaceListenAddresses()
+		if err != nil {
+			t.Fatal(err)
+		}
+		ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		log.Info("Connecting swarms simultaneously.")
+		for i := 0; i < 10; i++ { // connect 10x for each.
+			wg.Add(2)
+			go connect(swarms[0], swarms[1].local, ifaceAddrs1[0])
+			go connect(swarms[1], swarms[0].local, ifaceAddrs0[0])
+		}
+		wg.Wait()
+	}
+
+	// should still just have 1, at most 2 connections :)
+	c01l := len(swarms[0].ConnectionsToPeer(swarms[1].local))
+	if c01l > 2 {
+		t.Error("0->1 has", c01l)
+	}
+	c10l := len(swarms[1].ConnectionsToPeer(swarms[0].local))
+	if c10l > 2 {
+		t.Error("1->0 has", c10l)
+	}
+
+	for _, s := range swarms {
+		s.Close()
+	}
+}
+
+func newSilentPeer(t *testing.T) (peer.ID, ma.Multiaddr, net.Listener) {
+	dst := testutil.RandPeerIDFatal(t)
+	lst, err := net.Listen("tcp", ":0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	addr, err := manet.FromNetAddr(lst.Addr())
+	if err != nil {
+		t.Fatal(err)
+	}
+	addrs := []ma.Multiaddr{addr}
+	addrs, err = addrutil.ResolveUnspecifiedAddresses(addrs, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log("new silent peer:", dst, addrs[0])
+	return dst, addrs[0], lst
+}
+
+func TestDialWait(t *testing.T) {
+	// t.Skip("skipping for another test")
+	t.Parallel()
+
+	ctx := context.Background()
+	swarms := makeSwarms(ctx, t, 1)
+	s1 := swarms[0]
+	defer s1.Close()
+
+	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
+	if os.Getenv("TRAVIS") == "1" {
+		s1.dialT = time.Second
+	}
+
+	// dial to a non-existent peer.
+	s2p, s2addr, s2l := newSilentPeer(t)
+	go acceptAndHang(s2l)
+	defer s2l.Close()
+	s1.peers.AddAddress(s2p, s2addr)
+
+	before := time.Now()
+	if c, err := s1.Dial(ctx, s2p); err == nil {
+		defer c.Close()
+		t.Fatal("error swarm dialing to unknown peer worked...", err)
+	} else {
+		t.Log("correctly got error:", err)
+	}
+	duration := time.Now().Sub(before)
+
+	dt := s1.dialT
+	if duration < dt*dialAttempts {
+		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
+	}
+	if duration > 2*dt*dialAttempts {
+		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
+	}
+
+	if !s1.backf.Backoff(s2p) {
+		t.Error("s2 should now be on backoff")
+	}
+}
+
+func TestDialBackoff(t *testing.T) {
+	// t.Skip("skipping for another test")
+	if os.Getenv("TRAVIS") == "1" {
+		t.Skip("travis will never have fun with this test")
+	}
+
+	t.Parallel()
+
+	ctx := context.Background()
+	swarms := makeSwarms(ctx, t, 2)
+	s1 := swarms[0]
+	s2 := swarms[1]
+	defer s1.Close()
+	defer s2.Close()
+
+	s1.dialT = time.Millisecond * 500 // lower timeout for tests.
+	s2.dialT = time.Millisecond * 500 // lower timeout for tests.
+
+	s2addrs, err := s2.InterfaceListenAddresses()
+	if err != nil {
+		t.Fatal(err)
+	}
+	s1.peers.AddAddresses(s2.local, s2addrs)
+
+	// dial to a non-existent peer.
+	s3p, s3addr, s3l := newSilentPeer(t)
+	go acceptAndHang(s3l)
+	defer s3l.Close()
+	s1.peers.AddAddress(s3p, s3addr)
+
+	// in this test we will:
+	//   1) dial 10x to each node.
+	//   2) all dials should hang
+	//   3) s1->s2 should succeed.
+	//   4) s1->s3 should not (and should place s3 on backoff)
+	//   5) disconnect entirely
+	//   6) dial 10x to each node again
+	//   7) s3 dials should all return immediately (except 1)
+	//   8) s2 dials should all hang, and succeed
+	//   9) last s3 dial ends, unsuccessful
+
+	dialOnlineNode := func(dst peer.ID, times int) <-chan bool {
+		ch := make(chan bool)
+		for i := 0; i < times; i++ {
+			go func() {
+				if _, err := s1.Dial(ctx, dst); err != nil {
+					t.Error("error dialing", dst, err)
+					ch <- false
+				} else {
+					ch <- true
+				}
+			}()
+		}
+		return ch
+	}
+
+	dialOfflineNode := func(dst peer.ID, times int) <-chan bool {
+		ch := make(chan bool)
+		for i := 0; i < times; i++ {
+			go func() {
+				if c, err := s1.Dial(ctx, dst); err != nil {
+					ch <- false
+				} else {
+					t.Error("succeeded in dialing", dst)
+					ch <- true
+					c.Close()
+				}
+			}()
+		}
+		return ch
+	}
+
+	{
+		// 1) dial 10x to each node.
+		N := 10
+		s2done := dialOnlineNode(s2.local, N)
+		s3done := dialOfflineNode(s3p, N)
+
+		// when all dials should be done by:
+		dialTimeout1x := time.After(s1.dialT)
+		dialTimeout1Ax := time.After(s1.dialT * dialAttempts)
+		dialTimeout10Ax := time.After(s1.dialT * dialAttempts * 10)
+
+		// 2) all dials should hang
+		select {
+		case <-s2done:
+			t.Error("s2 should not happen immediately")
+		case <-s3done:
+			t.Error("s3 should not happen yet")
+		case <-time.After(time.Millisecond):
+			// s2 may finish very quickly, so let's get out.
+		}
+
+		// 3) s1->s2 should succeed.
+		for i := 0; i < N; i++ {
+			select {
+			case r := <-s2done:
+				if !r {
+					t.Error("s2 should not fail")
+				}
+			case <-s3done:
+				t.Error("s3 should not happen yet")
+			case <-dialTimeout1x:
+				t.Error("s2 took too long")
+			}
+		}
+
+		select {
+		case <-s2done:
+			t.Error("s2 should have no more")
+		case <-s3done:
+			t.Error("s3 should not happen yet")
+		case <-dialTimeout1x: // let it pass
+		}
+
+		// 4) s1->s3 should not (and should place s3 on backoff)
+		// N-1 should finish before dialTimeout1Ax
+		for i := 0; i < N; i++ {
+			select {
+			case <-s2done:
+				t.Error("s2 should have no more")
+			case r := <-s3done:
+				if r {
+					t.Error("s3 should not succeed")
+				}
+			case <-dialTimeout1Ax:
+				if i < (N - 1) {
+					t.Fatal("s3 took too long")
+				}
+				t.Log("dialTimeout1Ax hit for last peer")
+			case <-dialTimeout10Ax:
+				t.Fatal("s3 took too long")
+			}
+		}
+
+		// check backoff state
+		if s1.backf.Backoff(s2.local) {
+			t.Error("s2 should not be on backoff")
+		}
+		if !s1.backf.Backoff(s3p) {
+			t.Error("s3 should be on backoff")
+		}
+
+		// 5) disconnect entirely
+
+		for _, c := range s1.Connections() {
+			c.Close()
+		}
+		for i := 0; i < 100 && len(s1.Connections()) > 0; i++ {
+			<-time.After(time.Millisecond)
+		}
+		if len(s1.Connections()) > 0 {
+			t.Fatal("s1 conns must exit")
+		}
+	}
+
+	{
+		// 6) dial 10x to each node again
+		N := 10
+		s2done := dialOnlineNode(s2.local, N)
+		s3done := dialOfflineNode(s3p, N)
+
+		// when all dials should be done by:
+		dialTimeout1x := time.After(s1.dialT)
+		dialTimeout1Ax := time.After(s1.dialT * dialAttempts)
+		dialTimeout10Ax := time.After(s1.dialT * dialAttempts * 10)
+
+		// 7) s3 dials should all return immediately (except 1)
+		for i := 0; i < N-1; i++ {
+			select {
+			case <-s2done:
+				t.Error("s2 should not succeed yet")
+			case r := <-s3done:
+				if r {
+					t.Error("s3 should not succeed")
+				}
+			case <-dialTimeout1x:
+				t.Fatal("s3 took too long")
+			}
+		}
+
+		// 8) s2 dials should all hang, and succeed
+		for i := 0; i < N; i++ {
+			select {
+			case r := <-s2done:
+				if !r {
+					t.Error("s2 should succeed")
+				}
+			// case <-s3done:
+			case <-dialTimeout1Ax:
+				t.Fatal("s3 took too long")
+			}
+		}
+
+		// 9) the last s3 should return, failed.
+		select {
+		case <-s2done:
+			t.Error("s2 should have no more")
+		case r := <-s3done:
+			if r {
+				t.Error("s3 should not succeed")
+			}
+		case <-dialTimeout10Ax:
+			t.Fatal("s3 took too long")
+		}
+
+		// check backoff state (the same)
+		if s1.backf.Backoff(s2.local) {
+			t.Error("s2 should not be on backoff")
+		}
+		if !s1.backf.Backoff(s3p) {
+			t.Error("s3 should be on backoff")
+		}
+
+	}
+}
+
+func TestDialBackoffClears(t *testing.T) {
+	// t.Skip("skipping for another test")
+	t.Parallel()
+
+	ctx := context.Background()
+	swarms := makeSwarms(ctx, t, 2)
+	s1 := swarms[0]
+	s2 := swarms[1]
+	defer s1.Close()
+	defer s2.Close()
+	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
+	s2.dialT = time.Millisecond * 300 // lower timeout for tests.
+	if os.Getenv("TRAVIS") == "1" {
+		s1.dialT = time.Second
+		s2.dialT = time.Second
+	}
+
+	// use another address first, that accept and hang on conns
+	_, s2bad, s2l := newSilentPeer(t)
+	go acceptAndHang(s2l)
+	defer s2l.Close()
+
+	// phase 1 -- dial to non-operational addresses
+	s1.peers.AddAddress(s2.local, s2bad)
+
+	before := time.Now()
+	if c, err := s1.Dial(ctx, s2.local); err == nil {
+		t.Fatal("dialing to broken addr worked...", err)
+		defer c.Close()
+	} else {
+		t.Log("correctly got error:", err)
+	}
+	duration := time.Now().Sub(before)
+
+	dt := s1.dialT
+	if duration < dt*dialAttempts {
+		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
+	}
+	if duration > 2*dt*dialAttempts {
+		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
+	}
+
+	if !s1.backf.Backoff(s2.local) {
+		t.Error("s2 should now be on backoff")
+	} else {
+		t.Log("correctly added to backoff")
+	}
+
+	// phase 2 -- add the working address. dial should succeed.
+	ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
+	if err != nil {
+		t.Fatal(err)
+	}
+	s1.peers.AddAddresses(s2.local, ifaceAddrs1)
+
+	before = time.Now()
+	if c, err := s1.Dial(ctx, s2.local); err != nil {
+		t.Fatal(err)
+	} else {
+		c.Close()
+		t.Log("correctly connected")
+	}
+	duration = time.Now().Sub(before)
+
+	if duration >= dt {
+		// t.Error("took too long", duration, dt)
+	}
+
+	if s1.backf.Backoff(s2.local) {
+		t.Error("s2 should no longer be on backoff")
+	} else {
+		t.Log("correctly cleared backoff")
+	}
+}

net/swarm/simul_test.go

@@ -11,51 +11,9 @@ import (
 	ma "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr"
 )
 
-func TestSimultDials(t *testing.T) {
-	// t.Skip("skipping for another test")
-
-	ctx := context.Background()
-	swarms := makeSwarms(ctx, t, 2)
-
-	// connect everyone
-	{
-		var wg sync.WaitGroup
-		connect := func(s *Swarm, dst peer.ID, addr ma.Multiaddr) {
-			// copy for other peer
-			log.Debugf("TestSimultOpen: connecting: %s --> %s (%s)", s.local, dst, addr)
-			s.peers.AddAddress(dst, addr)
-			if _, err := s.Dial(ctx, dst); err != nil {
-				t.Fatal("error swarm dialing to peer", err)
-			}
-			wg.Done()
-		}
-
-		log.Info("Connecting swarms simultaneously.")
-		for i := 0; i < 10; i++ { // connect 10x for each.
-			wg.Add(2)
-			go connect(swarms[0], swarms[1].local, swarms[1].ListenAddresses()[0])
-			go connect(swarms[1], swarms[0].local, swarms[0].ListenAddresses()[0])
-		}
-		wg.Wait()
-	}
-
-	// should still just have 1, at most 2 connections :)
-	c01l := len(swarms[0].ConnectionsToPeer(swarms[1].local))
-	if c01l > 2 {
-		t.Error("0->1 has", c01l)
-	}
-	c10l := len(swarms[1].ConnectionsToPeer(swarms[0].local))
-	if c10l > 2 {
-		t.Error("1->0 has", c10l)
-	}
-
-	for _, s := range swarms {
-		s.Close()
-	}
-}
-
 func TestSimultOpen(t *testing.T) {
 	// t.Skip("skipping for another test")
+	t.Parallel()
 
 	ctx := context.Background()
 	swarms := makeSwarms(ctx, t, 2)
@@ -87,6 +45,7 @@ func TestSimultOpen(t *testing.T) {
 
 func TestSimultOpenMany(t *testing.T) {
 	// t.Skip("very very slow")
+	t.Parallel()
 
 	addrs := 20
 	SubtestSwarm(t, addrs, 10)
@@ -97,6 +56,7 @@ func TestSimultOpenFewStress(t *testing.T) {
 		t.SkipNow()
 	}
 	// t.Skip("skipping for another test")
+	t.Parallel()
 
 	msgs := 40
 	swarms := 2

net/swarm/swarm.go

@@ -4,6 +4,7 @@ package swarm
 
 import (
 	"fmt"
+	"time"
 
 	inet "github.com/jbenet/go-ipfs/p2p/net"
 	addrutil "github.com/jbenet/go-ipfs/p2p/net/swarm/addr"
@@ -32,7 +33,10 @@ type Swarm struct {
 	local peer.ID
 	peers peer.Peerstore
 	connh ConnHandler
+
 	dsync dialsync
+	backf dialbackoff
+	dialT time.Duration // mainly for tests
 
 	cg ctxgroup.ContextGroup
 }
@@ -50,10 +54,11 @@ func NewSwarm(ctx context.Context, listenAddrs []ma.Multiaddr,
 	}
 
 	s := &Swarm{
-		swarm:   ps.NewSwarm(PSTransport),
-		local:   local,
-		peers:   peers,
-		cg:      ctxgroup.WithContext(ctx),
+		swarm: ps.NewSwarm(PSTransport),
+		local: local,
+		peers: peers,
+		cg:    ctxgroup.WithContext(ctx),
+		dialT: DialTimeout,
 	}
 
 	// configure Swarm

net/swarm/swarm_addr.go

@@ -22,14 +22,14 @@ func (s *Swarm) ListenAddresses() []ma.Multiaddr {
 // InterfaceListenAddresses returns a list of addresses at which this swarm
 // listens. It expands "any interface" addresses (/ip4/0.0.0.0, /ip6/::) to
 // use the known local interfaces.
-func InterfaceListenAddresses(s *Swarm) ([]ma.Multiaddr, error) {
+func (s *Swarm) InterfaceListenAddresses() ([]ma.Multiaddr, error) {
 	return addrutil.ResolveUnspecifiedAddresses(s.ListenAddresses(), nil)
 }
 
 // checkNATWarning checks if our observed addresses differ. if so,
 // informs the user that certain things might not work yet
 func checkNATWarning(s *Swarm, observed ma.Multiaddr, expected ma.Multiaddr) {
-	listen, err := InterfaceListenAddresses(s)
+	listen, err := s.InterfaceListenAddresses()
 	if err != nil {
 		log.Errorf("Error retrieving swarm.InterfaceListenAddresses: %s", err)
 		return

net/swarm/swarm_dial.go

@@ -3,7 +3,9 @@ package swarm
 import (
 	"errors"
 	"fmt"
+	"net"
 	"sync"
+	"time"
 
 	conn "github.com/jbenet/go-ipfs/p2p/net/conn"
 	addrutil "github.com/jbenet/go-ipfs/p2p/net/swarm/addr"
@@ -12,11 +14,28 @@ import (
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 	ma "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr"
+	manet "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multiaddr-net"
 )
 
+// Diagram of dial sync:
+//
+//   many callers of Dial()   synched w.  dials many addrs       results to callers
+//  ----------------------\    dialsync    use earliest            /--------------
+//  -----------------------\              |----------\           /----------------
+//  ------------------------>------------<-------     >---------<-----------------
+//  -----------------------|              \----x                 \----------------
+//  ----------------------|                \-----x                \---------------
+//                                         any may fail          if no addr at end
+//                                                             retry dialAttempt x
+
 // dialAttempts governs how many times a goroutine will try to dial a given peer.
 const dialAttempts = 3
 
+// DialTimeout is the amount of time each dial attempt has. We can think about making
+// this larger down the road, or putting more granular timeouts (i.e. within each
+// subcomponent of Dial)
+var DialTimeout time.Duration = time.Second * 10
+
 // dialsync is a small object that helps manage ongoing dials.
 // this way, if we receive many simultaneous dial requests, one
 // can do its thing, while the rest wait.
@@ -88,6 +107,71 @@ func (ds *dialsync) Unlock(dst peer.ID) {
 	ds.lock.Unlock()
 }
 
+// dialbackoff is a struct used to avoid over-dialing the same, dead peers.
+// Whenever we totally time out on a peer (all three attempts), we add them
+// to dialbackoff. Then, whenevers goroutines would _wait_ (dialsync), they
+// check dialbackoff. If it's there, they don't wait and exit promptly with
+// an error. (the single goroutine that is actually dialing continues to
+// dial). If a dial is successful, the peer is removed from backoff.
+// Example:
+//
+//  for {
+//  	if ok, wait := dialsync.Lock(p); !ok {
+//  		if backoff.Backoff(p) {
+//  			return errDialFailed
+//  		}
+//  		<-wait
+//  		continue
+//  	}
+//  	defer dialsync.Unlock(p)
+//  	c, err := actuallyDial(p)
+//  	if err != nil {
+//  		dialbackoff.AddBackoff(p)
+//  		continue
+//  	}
+//  	dialbackoff.Clear(p)
+//  }
+//
+type dialbackoff struct {
+	entries map[peer.ID]struct{}
+	lock    sync.RWMutex
+}
+
+func (db *dialbackoff) init() {
+	if db.entries == nil {
+		db.entries = make(map[peer.ID]struct{})
+	}
+}
+
+// Backoff returns whether the client should backoff from dialing
+// peeer p
+func (db *dialbackoff) Backoff(p peer.ID) bool {
+	db.lock.Lock()
+	db.init()
+	_, found := db.entries[p]
+	db.lock.Unlock()
+	return found
+}
+
+// AddBackoff lets other nodes know that we've entered backoff with
+// peer p, so dialers should not wait unnecessarily. We still will
+// attempt to dial with one goroutine, in case we get through.
+func (db *dialbackoff) AddBackoff(p peer.ID) {
+	db.lock.Lock()
+	db.init()
+	db.entries[p] = struct{}{}
+	db.lock.Unlock()
+}
+
+// Clear removes a backoff record. Clients should call this after a
+// successful Dial.
+func (db *dialbackoff) Clear(p peer.ID) {
+	db.lock.Lock()
+	db.init()
+	delete(db.entries, p)
+	db.lock.Unlock()
+}
+
 // Dial connects to a peer.
 //
 // The idea is that the client of Swarm does not need to know what network
@@ -95,6 +179,7 @@ func (ds *dialsync) Unlock(dst peer.ID) {
 // This allows us to use various transport protocols, do NAT traversal/relay,
 // etc. to achive connection.
 func (s *Swarm) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
+	log := log.Prefix("swarm %s dialing %s", s.local, p)
 	if p == s.local {
 		return nil, errors.New("Attempted connection to self!")
 	}
@@ -118,6 +203,13 @@ func (s *Swarm) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
 
 		// check if there's an ongoing dial to this peer
 		if ok, wait := s.dsync.Lock(p); !ok {
+
+			if s.backf.Backoff(p) {
+				log.Debugf("backoff")
+				return nil, fmt.Errorf("%s failed to dial %s, backing off.", s.local, p)
+			}
+
+			log.Debugf("waiting for ongoing dial")
 			select {
 			case <-wait: // wait for that dial to finish.
 				continue // and see if it worked (loop), OR we got an incoming dial.
@@ -128,13 +220,22 @@ func (s *Swarm) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
 
 		// ok, we have been charged to dial! let's do it.
 		// if it succeeds, dial will add the conn to the swarm itself.
-		conn, err = s.dial(ctx, p)
+		log.Debugf("dial start")
+		ctxT, _ := context.WithTimeout(ctx, s.dialT)
+		conn, err = s.dial(ctxT, p)
 		s.dsync.Unlock(p)
+		log.Debugf("dial end %s", conn)
 		if err != nil {
+			s.backf.AddBackoff(p) // let others know to backoff
+
 			continue // ok, we failed. try again. (if loop is done, our error is output)
 		}
+		s.backf.Clear(p) // okay, no longer need to backoff
 		return conn, nil
 	}
+	if err == nil {
+		err = fmt.Errorf("%s failed to dial %s after %d attempts", s.local, p, dialAttempts)
+	}
 	return nil, err
 }
 
@@ -162,13 +263,21 @@ func (s *Swarm) dial(ctx context.Context, p peer.ID) (*Conn, error) {
 	remoteAddrs = addrutil.FilterUsableAddrs(remoteAddrs)
 	// drop out any addrs that would just dial ourselves. use ListenAddresses
 	// as that is a more authoritative view than localAddrs.
-	remoteAddrs = addrutil.Subtract(remoteAddrs, s.ListenAddresses())
+	ila, _ := s.InterfaceListenAddresses()
+	remoteAddrs = addrutil.Subtract(remoteAddrs, ila)
+	remoteAddrs = addrutil.Subtract(remoteAddrs, s.peers.Addresses(s.local))
+	log.Debugf("%s swarm dialing %s -- remote:%s local:%s", s.local, p, remoteAddrs, s.ListenAddresses())
 	if len(remoteAddrs) == 0 {
 		return nil, errors.New("peer has no addresses")
 	}
 
 	// open connection to peer
 	d := &conn.Dialer{
+		Dialer: manet.Dialer{
+			Dialer: net.Dialer{
+				Timeout: s.dialT,
+			},
+		},
 		LocalPeer:  s.local,
 		LocalAddrs: localAddrs,
 		PrivateKey: sk,
@@ -196,34 +305,83 @@ func (s *Swarm) dial(ctx context.Context, p peer.ID) (*Conn, error) {
 func (s *Swarm) dialAddrs(ctx context.Context, d *conn.Dialer, p peer.ID, remoteAddrs []ma.Multiaddr) (conn.Conn, error) {
 
 	// try to connect to one of the peer's known addresses.
-	// for simplicity, we do this sequentially.
-	// A future commit will do this asynchronously.
+	// we dial concurrently to each of the addresses, which:
+	// * makes the process faster overall
+	// * attempts to get the fastest connection available.
+	// * mitigates the waste of trying bad addresses
+	log.Debugf("%s swarm dialing %s %s", s.local, p, remoteAddrs)
+
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel() // cancel work when we exit func
+
+	foundConn := make(chan struct{})
+	conns := make(chan conn.Conn, len(remoteAddrs))
+	errs := make(chan error, len(remoteAddrs))
+
+	//TODO: rate limiting just in case?
 	for _, addr := range remoteAddrs {
-		connC, err := d.Dial(ctx, addr, p)
-		if err != nil {
-			continue
-		}
+		go func(addr ma.Multiaddr) {
+			connC, err := s.dialAddr(ctx, d, p, addr)
 
-		// if the connection is not to whom we thought it would be...
-		if connC.RemotePeer() != p {
-			log.Infof("misdial to %s through %s (got %s)", p, addr, connC.RemoteMultiaddr())
-			connC.Close()
-			continue
-		}
+			// check parent still wants our results
+			select {
+			case <-foundConn:
+				if connC != nil {
+					connC.Close()
+				}
+				return
+			default:
+			}
+
+			if err != nil {
+				errs <- err
+			} else if connC == nil {
+				errs <- fmt.Errorf("failed to dial %s %s", p, addr)
+			} else {
+				conns <- connC
+			}
+		}(addr)
+	}
 
-		// if the connection is to ourselves...
-		// this can happen TONS when Loopback addrs are advertized.
-		// (this should be caught by two checks above, but let's just make sure.)
-		if connC.RemotePeer() == s.local {
-			log.Infof("misdial to %s through %s", p, addr)
-			connC.Close()
-			continue
+	err := fmt.Errorf("failed to dial %s", p)
+	for i := 0; i < len(remoteAddrs); i++ {
+		select {
+		case err = <-errs:
+			log.Info(err)
+		case connC := <-conns:
+			// take the first + return asap
+			close(foundConn)
+			return connC, nil
 		}
+	}
+	return nil, err
+}
+
+func (s *Swarm) dialAddr(ctx context.Context, d *conn.Dialer, p peer.ID, addr ma.Multiaddr) (conn.Conn, error) {
+	log.Debugf("%s swarm dialing %s %s", s.local, p, addr)
 
-		// success! we got one!
-		return connC, nil
+	connC, err := d.Dial(ctx, addr, p)
+	if err != nil {
+		return nil, fmt.Errorf("%s --> %s dial attempt failed: %s", s.local, p, err)
+	}
+
+	// if the connection is not to whom we thought it would be...
+	remotep := connC.RemotePeer()
+	if remotep != p {
+		connC.Close()
+		return nil, fmt.Errorf("misdial to %s through %s (got %s)", p, addr, remotep)
 	}
-	return nil, fmt.Errorf("failed to dial %s", p)
+
+	// if the connection is to ourselves...
+	// this can happen TONS when Loopback addrs are advertized.
+	// (this should be caught by two checks above, but let's just make sure.)
+	if remotep == s.local {
+		connC.Close()
+		return nil, fmt.Errorf("misdial to %s through %s (got self)", p, addr)
+	}
+
+	// success! we got one!
+	return connC, nil
 }
 
 // dialConnSetup is the setup logic for a connection from the dial side. it

net/swarm/swarm_net.go

@@ -111,7 +111,7 @@ func (n *Network) ListenAddresses() []ma.Multiaddr {
 // listens. It expands "any interface" addresses (/ip4/0.0.0.0, /ip6/::) to
 // use the known local interfaces.
 func (n *Network) InterfaceListenAddresses() ([]ma.Multiaddr, error) {
-	return InterfaceListenAddresses(n.Swarm())
+	return n.Swarm().InterfaceListenAddresses()
 }
 
 // Connectedness returns a state signaling connection capabilities

net/swarm/swarm_test.go

@@ -227,6 +227,7 @@ func SubtestSwarm(t *testing.T, SwarmNum int, MsgNum int) {
 
 func TestSwarm(t *testing.T) {
 	// t.Skip("skipping for another test")
+	t.Parallel()
 
 	// msgs := 1000
 	msgs := 100
@@ -236,6 +237,7 @@ func TestSwarm(t *testing.T) {
 
 func TestConnHandler(t *testing.T) {
 	// t.Skip("skipping for another test")
+	t.Parallel()
 
 	ctx := context.Background()
 	swarms := makeSwarms(ctx, t, 5)