mocknet: refuse to connect to self

The swarm does this as well and most of our services will fail if we don't have
this.

p2p/net/mock/mock.go

@@ -44,14 +44,9 @@ func FullMeshConnected(ctx context.Context, n int) (Mocknet, error) {
 		return nil, err
 	}
 
-	nets := m.Nets()
-	for _, n1 := range nets {
-		for _, n2 := range nets {
-			if _, err := m.ConnectNets(n1, n2); err != nil {
-				return nil, err
-			}
-		}
+	err = m.ConnectAllButSelf()
+	if err != nil {
+		return nil, err
 	}
-
 	return m, nil
 }

p2p/net/mock/mock_peernet.go

@@ -118,6 +118,10 @@ func (pn *peernet) DialPeer(ctx context.Context, p peer.ID) (inet.Conn, error) {
 }
 
 func (pn *peernet) connect(p peer.ID) (*conn, error) {
+	if p == pn.peer {
+		return nil, fmt.Errorf("attempted to dial self %s", p)
+	}
+
 	// first, check if we already have live connections
 	pn.RLock()
 	cs, found := pn.connsByPeer[p]

p2p/net/mock/mock_test.go

@@ -225,14 +225,14 @@ func TestNetworkSetup(t *testing.T) {
 		t.Error("should not be able to connect")
 	}
 
-	// connect p1->p1 (should work)
-	if _, err := n1.DialPeer(ctx, p1); err != nil {
-		t.Error("p1 should be able to dial self.", err)
+	// connect p1->p1 (should fail)
+	if _, err := n1.DialPeer(ctx, p1); err == nil {
+		t.Error("p1 shouldn't be able to dial self")
 	}
 
 	// and a stream too
-	if _, err := n1.NewStream(ctx, p1); err != nil {
-		t.Error(err)
+	if _, err := n1.NewStream(ctx, p1); err == nil {
+		t.Error("p1 shouldn't be able to dial self")
 	}
 
 	// connect p1->p2
@@ -383,8 +383,11 @@ func TestStreamsStress(t *testing.T) {
 		wg.Add(1)
 		go func(i int) {
 			defer wg.Done()
-			from := rand.Intn(len(hosts))
-			to := rand.Intn(len(hosts))
+			var from, to int
+			for from == to {
+				from = rand.Intn(len(hosts))
+				to = rand.Intn(len(hosts))
+			}
 			s, err := hosts[from].NewStream(ctx, hosts[to].ID(), protocol.TestingID)
 			if err != nil {
 				log.Debugf("%d (%s) %d (%s)", from, hosts[from], to, hosts[to])