Test the nat mapper.

probe/endpoint/conntrack.go

@@ -65,8 +65,14 @@ type conntrack struct {
 	Flows   []Flow   `xml:"flow"`
 }
 
+// Conntracker is somethin that tracks connections.
+type Conntracker interface {
+	WalkFlows(f func(Flow))
+	Stop()
+}
+
 // Conntracker uses the conntrack command to track network connections
-type Conntracker struct {
+type conntracker struct {
 	sync.Mutex
 	cmd           exec.Cmd
 	activeFlows   map[int64]Flow // active flows in state != TIME_WAIT
@@ -75,11 +81,11 @@ type Conntracker struct {
 }
 
 // NewConntracker creates and starts a new Conntracter
-func NewConntracker(existingConns bool, args ...string) (*Conntracker, error) {
+var NewConntracker = func(existingConns bool, args ...string) (Conntracker, error) {
 	if !ConntrackModulePresent() {
 		return nil, fmt.Errorf("No conntrack module")
 	}
-	result := &Conntracker{
+	result := &conntracker{
 		activeFlows:   map[int64]Flow{},
 		existingConns: existingConns,
 	}
@@ -112,7 +118,7 @@ var ConntrackModulePresent = func() bool {
 }
 
 // NB this is not re-entrant!
-func (c *Conntracker) run(args ...string) {
+func (c *conntracker) run(args ...string) {
 	if c.existingConns {
 		// Fork another conntrack, just to capture existing connections
 		// for which we don't get events
@@ -178,7 +184,7 @@ func (c *Conntracker) run(args ...string) {
 	}
 }
 
-func (c *Conntracker) existingConnections(args ...string) ([]Flow, error) {
+func (c *conntracker) existingConnections(args ...string) ([]Flow, error) {
 	args = append([]string{"-L", "-o", "xml", "-p", "tcp"}, args...)
 	cmd := exec.Command("conntrack", args...)
 	stdout, err := cmd.StdoutPipe()
@@ -203,7 +209,7 @@ func (c *Conntracker) existingConnections(args ...string) ([]Flow, error) {
 }
 
 // Stop stop stop
-func (c *Conntracker) Stop() {
+func (c *conntracker) Stop() {
 	c.Lock()
 	defer c.Unlock()
 	if c.cmd == nil {
@@ -215,7 +221,7 @@ func (c *Conntracker) Stop() {
 	}
 }
 
-func (c *Conntracker) handleFlow(f Flow, forceAdd bool) {
+func (c *conntracker) handleFlow(f Flow, forceAdd bool) {
 	// A flow consists of 3 'metas' - the 'original' 4 tuple (as seen by this
 	// host) and the 'reply' 4 tuple, which is what it has been rewritten to.
 	// This code finds those metas, which are identified by a Direction
@@ -260,7 +266,7 @@ func (c *Conntracker) handleFlow(f Flow, forceAdd bool) {
 
 // WalkFlows calls f with all active flows and flows that have come and gone
 // since the last call to WalkFlows
-func (c *Conntracker) WalkFlows(f func(Flow)) {
+func (c *conntracker) WalkFlows(f func(Flow)) {
 	c.Lock()
 	defer c.Unlock()
 	for _, flow := range c.activeFlows {

probe/endpoint/conntrack_test.go

@@ -13,54 +13,62 @@ import (
 	testExec "github.com/weaveworks/scope/test/exec"
 )
 
-func makeFlow(id int64, srcIP, dstIP string, srcPort, dstPort int, ty, state string) Flow {
+func makeFlow(ty string) Flow {
 	return Flow{
 		XMLName: xml.Name{
 			Local: "flow",
 		},
 		Type: ty,
-		Metas: []Meta{
-			{
-				XMLName: xml.Name{
-					Local: "meta",
-				},
-				Direction: "original",
-				Layer3: Layer3{
-					XMLName: xml.Name{
-						Local: "layer3",
-					},
-					SrcIP: srcIP,
-					DstIP: dstIP,
-				},
-				Layer4: Layer4{
-					XMLName: xml.Name{
-						Local: "layer4",
-					},
-					SrcPort: srcPort,
-					DstPort: dstPort,
-					Proto:   TCP,
-				},
+	}
+}
+
+func addMeta(f *Flow, dir, srcIP, dstIP string, srcPort, dstPort int) *Meta {
+	meta := Meta{
+		XMLName: xml.Name{
+			Local: "meta",
+		},
+		Direction: dir,
+		Layer3: Layer3{
+			XMLName: xml.Name{
+				Local: "layer3",
 			},
-			{
-				XMLName: xml.Name{
-					Local: "meta",
-				},
-				Direction: "independent",
-				ID:        id,
-				State:     state,
-				Layer3: Layer3{
-					XMLName: xml.Name{
-						Local: "layer3",
-					},
-				},
-				Layer4: Layer4{
-					XMLName: xml.Name{
-						Local: "layer4",
-					},
-				},
+			SrcIP: srcIP,
+			DstIP: dstIP,
+		},
+		Layer4: Layer4{
+			XMLName: xml.Name{
+				Local: "layer4",
+			},
+			SrcPort: srcPort,
+			DstPort: dstPort,
+			Proto:   TCP,
+		},
+	}
+	f.Metas = append(f.Metas, meta)
+	return &meta
+}
+
+func addIndependant(f *Flow, id int64, state string) *Meta {
+	meta := Meta{
+		XMLName: xml.Name{
+			Local: "meta",
+		},
+		Direction: "independent",
+		ID:        id,
+		State:     state,
+		Layer3: Layer3{
+			XMLName: xml.Name{
+				Local: "layer3",
+			},
+		},
+		Layer4: Layer4{
+			XMLName: xml.Name{
+				Local: "layer4",
 			},
 		},
 	}
+	f.Metas = append(f.Metas, meta)
+	return &meta
 }
 
 func TestConntracker(t *testing.T) {
@@ -121,7 +129,9 @@ func TestConntracker(t *testing.T) {
 		}
 	}
 
-	flow1 := makeFlow(1, "1.2.3.4", "2.3.4.5", 2, 3, New, "")
+	flow1 := makeFlow(New)
+	addMeta(&flow1, "original", "1.2.3.4", "2.3.4.5", 2, 3)
+	addIndependant(&flow1, 1, "")
 	writeFlow(flow1)
 	test.Poll(t, ts, []Flow{flow1}, have)
 

probe/endpoint/nat.go

@@ -16,16 +16,18 @@ type endpointMapping struct {
 	rewrittenPort int
 }
 
-type natmapper struct {
-	*Conntracker
+// NATMapper rewrites a report to deal with NAT's connections
+type NATMapper struct {
+	Conntracker
 }
 
-func newNATMapper() (*natmapper, error) {
+// NewNATMapper is exposed for testing
+func NewNATMapper() (*NATMapper, error) {
 	ct, err := NewConntracker(true, "--any-nat")
 	if err != nil {
 		return nil, err
 	}
-	return &natmapper{ct}, nil
+	return &NATMapper{ct}, nil
 }
 
 func toMapping(f Flow) *endpointMapping {
@@ -49,9 +51,9 @@ func toMapping(f Flow) *endpointMapping {
 	return &mapping
 }
 
-// applyNAT duplicates Nodes in the endpoint topology of a
+// ApplyNAT duplicates Nodes in the endpoint topology of a
 // report, based on the NAT table as returns by natTable.
-func (n *natmapper) applyNAT(rpt report.Report, scope string) {
+func (n *NATMapper) ApplyNAT(rpt report.Report, scope string) {
 	n.WalkFlows(func(f Flow) {
 		var (
 			mapping          = toMapping(f)

probe/endpoint/nat_test.go

@@ -0,0 +1,64 @@
+package endpoint_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/weaveworks/scope/probe/endpoint"
+	"github.com/weaveworks/scope/report"
+	"github.com/weaveworks/scope/test"
+)
+
+type mockConntracker struct {
+	flows []endpoint.Flow
+}
+
+func (m *mockConntracker) WalkFlows(f func(endpoint.Flow)) {
+	for _, flow := range m.flows {
+		f(flow)
+	}
+}
+
+func (m *mockConntracker) Stop() {}
+
+func TestNat(t *testing.T) {
+	oldNewConntracker := endpoint.NewConntracker
+	defer func() { endpoint.NewConntracker = oldNewConntracker }()
+
+	endpoint.NewConntracker = func(existingConns bool, args ...string) (endpoint.Conntracker, error) {
+		flow := makeFlow("")
+		addIndependant(&flow, 1, "")
+		flow.Original = addMeta(&flow, "original", "10.0.47.1", "2.3.4.5", 80, 22222)
+		flow.Reply = addMeta(&flow, "reply", "2.3.4.5", "1.2.3.4", 22222, 80)
+
+		return &mockConntracker{
+			flows: []endpoint.Flow{flow},
+		}, nil
+	}
+
+	have := report.MakeReport()
+	originalID := report.MakeEndpointNodeID("host1", "10.0.47.1", "80")
+	have.Endpoint.AddNode(originalID, report.MakeNodeWith(report.Metadata{
+		endpoint.Addr: "10.0.47.1",
+		endpoint.Port: "80",
+		"foo":         "bar",
+	}))
+
+	want := have.Copy()
+	want.Endpoint.AddNode(report.MakeEndpointNodeID("host1", "1.2.3.4", "80"), report.MakeNodeWith(report.Metadata{
+		endpoint.Addr: "1.2.3.4",
+		endpoint.Port: "80",
+		"copy_of":     originalID,
+		"foo":         "bar",
+	}))
+
+	natmapper, err := endpoint.NewNATMapper()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	natmapper.ApplyNAT(have, "host1")
+	if !reflect.DeepEqual(want, have) {
+		t.Fatal(test.Diff(want, have))
+	}
+}

probe/endpoint/reporter.go

@@ -26,8 +26,8 @@ type Reporter struct {
 	hostName         string
 	includeProcesses bool
 	includeNAT       bool
-	conntracker      *Conntracker
-	natmapper        *natmapper
+	conntracker      Conntracker
+	natmapper        *NATMapper
 	revResolver      *ReverseResolver
 }
 
@@ -51,8 +51,8 @@ var SpyDuration = prometheus.NewSummaryVec(
 func NewReporter(hostID, hostName string, includeProcesses bool, useConntrack bool) *Reporter {
 	var (
 		conntrackModulePresent = ConntrackModulePresent()
-		conntracker            *Conntracker
-		natmapper              *natmapper
+		conntracker            Conntracker
+		natmapper              *NATMapper
 		err                    error
 	)
 	if conntrackModulePresent && useConntrack {
@@ -62,7 +62,7 @@ func NewReporter(hostID, hostName string, includeProcesses bool, useConntrack bo
 		}
 	}
 	if conntrackModulePresent {
-		natmapper, err = newNATMapper()
+		natmapper, err = NewNATMapper()
 		if err != nil {
 			log.Printf("Failed to start natMapper: %v", err)
 		}
@@ -139,7 +139,7 @@ func (r *Reporter) Report() (report.Report, error) {
 	}
 
 	if r.natmapper != nil {
-		r.natmapper.applyNAT(rpt, r.hostID)
+		r.natmapper.ApplyNAT(rpt, r.hostID)
 	}
 
 	return rpt, nil