Merge pull request #9 from libp2p/fix/nil-is-not-nil

avoid the nil is not nil footgun

p2p/host/resource-manager/rcmgr.go

@@ -474,6 +474,12 @@ func (s *peerScope) Peer() peer.ID {
 func (s *connectionScope) PeerScope() network.PeerScope {
 	s.Lock()
 	defer s.Unlock()
+
+	// avoid nil is not nil footgun; go....
+	if s.peer == nil {
+		return nil
+	}
+
 	return s.peer
 }
 
@@ -510,6 +516,12 @@ func (s *connectionScope) SetPeer(p peer.ID) error {
 func (s *streamScope) ProtocolScope() network.ProtocolScope {
 	s.Lock()
 	defer s.Unlock()
+
+	// avoid nil is not nil footgun; go....
+	if s.proto == nil {
+		return nil
+	}
+
 	return s.proto
 }
 
@@ -559,6 +571,12 @@ func (s *streamScope) SetProtocol(proto protocol.ID) error {
 func (s *streamScope) ServiceScope() network.ServiceScope {
 	s.Lock()
 	defer s.Unlock()
+
+	// avoid nil is not nil footgun; go....
+	if s.svc == nil {
+		return nil
+	}
+
 	return s.svc
 }
 
@@ -611,5 +629,11 @@ func (s *streamScope) SetService(svc string) error {
 func (s *streamScope) PeerScope() network.PeerScope {
 	s.Lock()
 	defer s.Unlock()
+
+	// avoid nil is not nil footgun; go....
+	if s.peer == nil {
+		return nil
+	}
+
 	return s.peer
 }

p2p/host/resource-manager/rcmgr_test.go

@@ -291,6 +291,11 @@ func TestResourceManager(t *testing.T) {
 		checkResources(t, &s.rc, network.ScopeStat{NumConnsInbound: 1, NumFD: 1})
 	})
 
+	// check nility of current peer scope
+	if conn1.PeerScope() != nil {
+		t.Fatal("peer scope should be nil")
+	}
+
 	// attach to a peer
 	if err := conn1.SetPeer(peerA); err != nil {
 		t.Fatal(err)
@@ -435,6 +440,11 @@ func TestResourceManager(t *testing.T) {
 		checkResources(t, &s.rc, network.ScopeStat{NumStreamsInbound: 1})
 	})
 
+	// check nility of protocol scope
+	if stream1.ProtocolScope() != nil {
+		t.Fatal("protocol scope should be nil")
+	}
+
 	if err := stream1.SetProtocol(protoA); err != nil {
 		t.Fatal(err)
 	}
@@ -574,6 +584,11 @@ func TestResourceManager(t *testing.T) {
 		checkResources(t, &s.rc, network.ScopeStat{})
 	})
 
+	// check nility of current service scope
+	if stream1.ServiceScope() != nil {
+		t.Fatal("service scope should be nil")
+	}
+
 	// we should be able to attach stream1 and stream2 to svcA, but stream3 should fail due to limit
 	if err := stream1.SetService(svcA); err != nil {
 		t.Fatal(err)