use ipset doing snat and packet filter in ipvs proxy

cmd/kube-proxy/app/BUILD

@@ -41,6 +41,7 @@ go_library(
         "//pkg/proxy/userspace:go_default_library",
         "//pkg/util/configz:go_default_library",
         "//pkg/util/dbus:go_default_library",
+        "//pkg/util/ipset:go_default_library",
         "//pkg/util/iptables:go_default_library",
         "//pkg/util/ipvs:go_default_library",
         "//pkg/util/mount:go_default_library",

cmd/kube-proxy/app/server.go

@@ -63,6 +63,7 @@ import (
 	"k8s.io/kubernetes/pkg/proxy/ipvs"
 	"k8s.io/kubernetes/pkg/proxy/userspace"
 	"k8s.io/kubernetes/pkg/util/configz"
+	utilipset "k8s.io/kubernetes/pkg/util/ipset"
 	utiliptables "k8s.io/kubernetes/pkg/util/iptables"
 	utilipvs "k8s.io/kubernetes/pkg/util/ipvs"
 	utilnode "k8s.io/kubernetes/pkg/util/node"
@@ -356,6 +357,7 @@ type ProxyServer struct {
 	EventClient            v1core.EventsGetter
 	IptInterface           utiliptables.Interface
 	IpvsInterface          utilipvs.Interface
+	IpsetInterface         utilipset.Interface
 	execer                 exec.Interface
 	Proxier                proxy.ProxyProvider
 	Broadcaster            record.EventBroadcaster
@@ -422,7 +424,7 @@ func (s *ProxyServer) Run() error {
 	if s.CleanupAndExit {
 		encounteredError := userspace.CleanupLeftovers(s.IptInterface)
 		encounteredError = iptables.CleanupLeftovers(s.IptInterface) || encounteredError
-		encounteredError = ipvs.CleanupLeftovers(s.IpvsInterface, s.IptInterface) || encounteredError
+		encounteredError = ipvs.CleanupLeftovers(s.IpvsInterface, s.IptInterface, s.IpsetInterface) || encounteredError
 		if encounteredError {
 			return errors.New("encountered an error while tearing down rules.")
 		}

cmd/kube-proxy/app/server_others.go

@@ -43,6 +43,7 @@ import (
 	"k8s.io/kubernetes/pkg/proxy/userspace"
 	"k8s.io/kubernetes/pkg/util/configz"
 	utildbus "k8s.io/kubernetes/pkg/util/dbus"
+	utilipset "k8s.io/kubernetes/pkg/util/ipset"
 	utiliptables "k8s.io/kubernetes/pkg/util/iptables"
 	utilipvs "k8s.io/kubernetes/pkg/util/ipvs"
 	utilnode "k8s.io/kubernetes/pkg/util/node"
@@ -72,6 +73,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 
 	var iptInterface utiliptables.Interface
 	var ipvsInterface utilipvs.Interface
+	var ipsetInterface utilipset.Interface
 	var dbus utildbus.Interface
 
 	// Create a iptables utils.
@@ -80,6 +82,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 	dbus = utildbus.New()
 	iptInterface = utiliptables.New(execer, dbus, protocol)
 	ipvsInterface = utilipvs.New(execer)
+	ipsetInterface = utilipset.New(execer)
 
 	// We omit creation of pretty much everything if we run in cleanup mode
 	if cleanupAndExit {
@@ -87,6 +90,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 			execer:         execer,
 			IptInterface:   iptInterface,
 			IpvsInterface:  ipvsInterface,
+			IpsetInterface: ipsetInterface,
 			CleanupAndExit: cleanupAndExit,
 		}, nil
 	}
@@ -119,7 +123,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 	var serviceEventHandler proxyconfig.ServiceHandler
 	var endpointsEventHandler proxyconfig.EndpointsHandler
 
-	proxyMode := getProxyMode(string(config.Mode), iptInterface, iptables.LinuxKernelCompatTester{})
+	proxyMode := getProxyMode(string(config.Mode), iptInterface, ipsetInterface, iptables.LinuxKernelCompatTester{})
 	if proxyMode == proxyModeIPTables {
 		glog.V(0).Info("Using iptables Proxier.")
 		nodeIP := net.ParseIP(config.BindAddress)
@@ -159,12 +163,13 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 		userspace.CleanupLeftovers(iptInterface)
 		// IPVS Proxier will generate some iptables rules,
 		// need to clean them before switching to other proxy mode.
-		ipvs.CleanupLeftovers(ipvsInterface, iptInterface)
+		ipvs.CleanupLeftovers(ipvsInterface, iptInterface, ipsetInterface)
 	} else if proxyMode == proxyModeIPVS {
 		glog.V(0).Info("Using ipvs Proxier.")
 		proxierIPVS, err := ipvs.NewProxier(
 			iptInterface,
 			ipvsInterface,
+			ipsetInterface,
 			utilsysctl.New(),
 			execer,
 			config.IPVS.SyncPeriod.Duration,
@@ -220,7 +225,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 		iptables.CleanupLeftovers(iptInterface)
 		// IPVS Proxier will generate some iptables rules,
 		// need to clean them before switching to other proxy mode.
-		ipvs.CleanupLeftovers(ipvsInterface, iptInterface)
+		ipvs.CleanupLeftovers(ipvsInterface, iptInterface, ipsetInterface)
 	}
 
 	iptInterface.AddReloadFunc(proxier.Sync)
@@ -230,6 +235,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 		EventClient:            eventClient,
 		IptInterface:           iptInterface,
 		IpvsInterface:          ipvsInterface,
+		IpsetInterface:         ipsetInterface,
 		execer:                 execer,
 		Proxier:                proxier,
 		Broadcaster:            eventBroadcaster,
@@ -249,7 +255,7 @@ func NewProxyServer(config *proxyconfigapi.KubeProxyConfiguration, cleanupAndExi
 	}, nil
 }
 
-func getProxyMode(proxyMode string, iptver iptables.IPTablesVersioner, kcompat iptables.KernelCompatTester) string {
+func getProxyMode(proxyMode string, iptver iptables.IPTablesVersioner, ipsetver ipvs.IPSetVersioner, kcompat iptables.KernelCompatTester) string {
 	if proxyMode == proxyModeUserspace {
 		return proxyModeUserspace
 	}
@@ -260,7 +266,7 @@ func getProxyMode(proxyMode string, iptver iptables.IPTablesVersioner, kcompat i
 
 	if utilfeature.DefaultFeatureGate.Enabled(features.SupportIPVSProxyMode) {
 		if proxyMode == proxyModeIPVS {
-			return tryIPVSProxy(iptver, kcompat)
+			return tryIPVSProxy(iptver, ipsetver, kcompat)
 		} else {
 			glog.Warningf("Can't use ipvs proxier, trying iptables proxier")
 			return tryIPTablesProxy(iptver, kcompat)
@@ -270,10 +276,10 @@ func getProxyMode(proxyMode string, iptver iptables.IPTablesVersioner, kcompat i
 	return tryIPTablesProxy(iptver, kcompat)
 }
 
-func tryIPVSProxy(iptver iptables.IPTablesVersioner, kcompat iptables.KernelCompatTester) string {
+func tryIPVSProxy(iptver iptables.IPTablesVersioner, ipsetver ipvs.IPSetVersioner, kcompat iptables.KernelCompatTester) string {
 	// guaranteed false on error, error only necessary for debugging
-	// IPVS Proxier relies on iptables
-	useIPVSProxy, err := ipvs.CanUseIPVSProxier()
+	// IPVS Proxier relies on ipset
+	useIPVSProxy, err := ipvs.CanUseIPVSProxier(ipsetver)
 	if err != nil {
 		// Try to fallback to iptables before falling back to userspace
 		utilruntime.HandleError(fmt.Errorf("can't determine whether to use ipvs proxy, error: %v", err))
@@ -282,8 +288,6 @@ func tryIPVSProxy(iptver iptables.IPTablesVersioner, kcompat iptables.KernelComp
 		return proxyModeIPVS
 	}
 
-	// TODO: Check ipvs version
-
 	// Try to fallback to iptables before falling back to userspace
 	glog.V(1).Infof("Can't use ipvs proxier, trying iptables proxier")
 	return tryIPTablesProxy(iptver, kcompat)

pkg/proxy/ipvs/BUILD

@@ -9,6 +9,7 @@ load(
 go_test(
     name = "go_default_test",
     srcs = [
+        "ipset_test.go",
         "proxier_test.go",
     ],
     importpath = "k8s.io/kubernetes/pkg/proxy/ipvs",
@@ -18,6 +19,8 @@ go_test(
         "//pkg/proxy:go_default_library",
         "//pkg/proxy/ipvs/testing:go_default_library",
         "//pkg/proxy/util:go_default_library",
+        "//pkg/util/ipset:go_default_library",
+        "//pkg/util/ipset/testing:go_default_library",
         "//pkg/util/iptables:go_default_library",
         "//pkg/util/iptables/testing:go_default_library",
         "//pkg/util/ipvs:go_default_library",
@@ -35,6 +38,7 @@ go_test(
 go_library(
     name = "go_default_library",
     srcs = [
+        "ipset.go",
         "netlink.go",
         "netlink_unsupported.go",
         "proxier.go",
@@ -55,9 +59,11 @@ go_library(
         "//pkg/proxy/metrics:go_default_library",
         "//pkg/proxy/util:go_default_library",
         "//pkg/util/async:go_default_library",
+        "//pkg/util/ipset:go_default_library",
         "//pkg/util/iptables:go_default_library",
         "//pkg/util/ipvs:go_default_library",
         "//pkg/util/sysctl:go_default_library",
+        "//pkg/util/version:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",

pkg/proxy/ipvs/proxier_test.go

@@ -33,6 +33,8 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	netlinktest "k8s.io/kubernetes/pkg/proxy/ipvs/testing"
 	proxyutil "k8s.io/kubernetes/pkg/proxy/util"
+	utilipset "k8s.io/kubernetes/pkg/util/ipset"
+	ipsettest "k8s.io/kubernetes/pkg/util/ipset/testing"
 	utiliptables "k8s.io/kubernetes/pkg/util/iptables"
 	iptablestest "k8s.io/kubernetes/pkg/util/iptables/testing"
 	utilipvs "k8s.io/kubernetes/pkg/util/ipvs"
@@ -85,7 +87,7 @@ func (fake *fakeHealthChecker) SyncEndpoints(newEndpoints map[types.NamespacedNa
 	return nil
 }
 
-func NewFakeProxier(ipt utiliptables.Interface, ipvs utilipvs.Interface, nodeIPs []net.IP) *Proxier {
+func NewFakeProxier(ipt utiliptables.Interface, ipvs utilipvs.Interface, ipset utilipset.Interface, nodeIPs []net.IP) *Proxier {
 	fcmd := fakeexec.FakeCmd{
 		CombinedOutputScript: []fakeexec.FakeCombinedOutputAction{
 			func() ([]byte, error) { return []byte("dummy device have been created"), nil },
@@ -98,24 +100,34 @@ func NewFakeProxier(ipt utiliptables.Interface, ipvs utilipvs.Interface, nodeIPs
 		LookPathFunc: func(cmd string) (string, error) { return cmd, nil },
 	}
 	return &Proxier{
-		exec:             fexec,
-		serviceMap:       make(proxyServiceMap),
-		serviceChanges:   newServiceChangeMap(),
-		endpointsMap:     make(proxyEndpointsMap),
-		endpointsChanges: newEndpointsChangeMap(testHostname),
-		iptables:         ipt,
-		ipvs:             ipvs,
-		clusterCIDR:      "10.0.0.0/24",
-		hostname:         testHostname,
-		portsMap:         make(map[proxyutil.LocalPort]proxyutil.Closeable),
-		portMapper:       &fakePortOpener{[]*proxyutil.LocalPort{}},
-		healthChecker:    newFakeHealthChecker(),
-		ipvsScheduler:    DefaultScheduler,
-		ipGetter:         &fakeIPGetter{nodeIPs: nodeIPs},
-		iptablesData:     bytes.NewBuffer(nil),
-		natChains:        bytes.NewBuffer(nil),
-		natRules:         bytes.NewBuffer(nil),
-		netlinkHandle:    netlinktest.NewFakeNetlinkHandle(),
+		exec:               fexec,
+		serviceMap:         make(proxyServiceMap),
+		serviceChanges:     newServiceChangeMap(),
+		endpointsMap:       make(proxyEndpointsMap),
+		endpointsChanges:   newEndpointsChangeMap(testHostname),
+		iptables:           ipt,
+		ipvs:               ipvs,
+		ipset:              ipset,
+		clusterCIDR:        "10.0.0.0/24",
+		hostname:           testHostname,
+		portsMap:           make(map[proxyutil.LocalPort]proxyutil.Closeable),
+		portMapper:         &fakePortOpener{[]*proxyutil.LocalPort{}},
+		healthChecker:      newFakeHealthChecker(),
+		ipvsScheduler:      DefaultScheduler,
+		ipGetter:           &fakeIPGetter{nodeIPs: nodeIPs},
+		iptablesData:       bytes.NewBuffer(nil),
+		natChains:          bytes.NewBuffer(nil),
+		natRules:           bytes.NewBuffer(nil),
+		netlinkHandle:      netlinktest.NewFakeNetlinkHandle(),
+		loopbackSet:        NewIPSet(ipset, KubeLoopBackIPSet, utilipset.HashIPPortIP, false),
+		clusterIPSet:       NewIPSet(ipset, KubeClusterIPSet, utilipset.HashIPPort, false),
+		externalIPSet:      NewIPSet(ipset, KubeExternalIPSet, utilipset.HashIPPort, false),
+		lbIngressSet:       NewIPSet(ipset, KubeLoadBalancerSet, utilipset.HashIPPort, false),
+		lbMasqSet:          NewIPSet(ipset, KubeLoadBalancerMasqSet, utilipset.HashIPPort, false),
+		lbWhiteListIPSet:   NewIPSet(ipset, KubeLoadBalancerSourceIPSet, utilipset.HashIPPortIP, false),
+		lbWhiteListCIDRSet: NewIPSet(ipset, KubeLoadBalancerSourceCIDRSet, utilipset.HashIPPortNet, false),
+		nodePortSetTCP:     NewIPSet(ipset, KubeNodePortSetTCP, utilipset.BitmapPort, false),
+		nodePortSetUDP:     NewIPSet(ipset, KubeNodePortSetUDP, utilipset.BitmapPort, false),
 	}
 }
 
@@ -171,10 +183,11 @@ func makeTestEndpoints(namespace, name string, eptFunc func(*api.Endpoints)) *ap
 func TestNodePort(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
+	ipset := ipsettest.NewFake()
 	nodeIPv4 := net.ParseIP("100.101.102.103")
 	nodeIPv6 := net.ParseIP("2001:db8::1:1")
 	nodeIPs := sets.NewString(nodeIPv4.String(), nodeIPv6.String())
-	fp := NewFakeProxier(ipt, ipvs, []net.IP{nodeIPv4, nodeIPv6})
+	fp := NewFakeProxier(ipt, ipvs, ipset, []net.IP{nodeIPv4, nodeIPv6})
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -248,8 +261,9 @@ func TestNodePort(t *testing.T) {
 func TestNodePortNoEndpoint(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
+	ipset := ipsettest.NewFake()
 	nodeIP := net.ParseIP("100.101.102.103")
-	fp := NewFakeProxier(ipt, ipvs, []net.IP{nodeIP})
+	fp := NewFakeProxier(ipt, ipvs, ipset, []net.IP{nodeIP})
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -301,7 +315,8 @@ func TestNodePortNoEndpoint(t *testing.T) {
 func TestClusterIPNoEndpoint(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcPortName := proxy.ServicePortName{
@@ -344,7 +359,8 @@ func TestClusterIPNoEndpoint(t *testing.T) {
 func TestClusterIP(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 
 	svcIPv4 := "10.20.30.41"
 	svcPortV4 := 80
@@ -450,7 +466,8 @@ func TestClusterIP(t *testing.T) {
 func TestExternalIPsNoEndpoint(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcExternalIPs := "50.60.70.81"
@@ -504,7 +521,8 @@ func TestExternalIPsNoEndpoint(t *testing.T) {
 func TestExternalIPs(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcExternalIPs := sets.NewString("50.60.70.81", "2012::51")
@@ -573,7 +591,8 @@ func TestExternalIPs(t *testing.T) {
 func TestLoadBalancer(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -624,8 +643,9 @@ func strPtr(s string) *string {
 func TestOnlyLocalNodePorts(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
+	ipset := ipsettest.NewFake()
 	nodeIP := net.ParseIP("100.101.102.103")
-	fp := NewFakeProxier(ipt, ipvs, []net.IP{nodeIP})
+	fp := NewFakeProxier(ipt, ipvs, ipset, []net.IP{nodeIP})
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -705,7 +725,8 @@ func TestOnlyLocalNodePorts(t *testing.T) {
 func TestOnlyLocalLoadBalancing(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -769,7 +790,8 @@ func addTestPort(array []api.ServicePort, name string, protocol api.Protocol, po
 func TestBuildServiceMapAddRemove(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 
 	services := []*api.Service{
 		makeTestService("somewhere-else", "cluster-ip", func(svc *api.Service) {
@@ -874,7 +896,8 @@ func TestBuildServiceMapAddRemove(t *testing.T) {
 func TestBuildServiceMapServiceHeadless(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 
 	makeServiceMap(fp,
 		makeTestService("somewhere-else", "headless", func(svc *api.Service) {
@@ -907,7 +930,8 @@ func TestBuildServiceMapServiceHeadless(t *testing.T) {
 func TestBuildServiceMapServiceTypeExternalName(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 
 	makeServiceMap(fp,
 		makeTestService("somewhere-else", "external-name", func(svc *api.Service) {
@@ -934,7 +958,8 @@ func TestBuildServiceMapServiceTypeExternalName(t *testing.T) {
 func TestBuildServiceMapServiceUpdate(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
-	fp := NewFakeProxier(ipt, ipvs, nil)
+	ipset := ipsettest.NewFake()
+	fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 
 	servicev1 := makeTestService("somewhere", "some-service", func(svc *api.Service) {
 		svc.Spec.Type = api.ServiceTypeClusterIP
@@ -1016,8 +1041,9 @@ func TestBuildServiceMapServiceUpdate(t *testing.T) {
 func TestSessionAffinity(t *testing.T) {
 	ipt := iptablestest.NewFake()
 	ipvs := ipvstest.NewFake()
+	ipset := ipsettest.NewFake()
 	nodeIP := net.ParseIP("100.101.102.103")
-	fp := NewFakeProxier(ipt, ipvs, []net.IP{nodeIP})
+	fp := NewFakeProxier(ipt, ipvs, ipset, []net.IP{nodeIP})
 	svcIP := "10.20.30.41"
 	svcPort := 80
 	svcNodePort := 3001
@@ -1879,7 +1905,8 @@ func Test_updateEndpointsMap(t *testing.T) {
 	for tci, tc := range testCases {
 		ipt := iptablestest.NewFake()
 		ipvs := ipvstest.NewFake()
-		fp := NewFakeProxier(ipt, ipvs, nil)
+		ipset := ipsettest.NewFake()
+		fp := NewFakeProxier(ipt, ipvs, ipset, nil)
 		fp.hostname = nodeName
 
 		// First check that after adding all previous versions of endpoints,

pkg/proxy/util/endpoints.go

@@ -19,6 +19,7 @@ package util
 import (
 	"fmt"
 	"net"
+	"strconv"
 
 	"github.com/golang/glog"
 )
@@ -40,6 +41,21 @@ func IPPart(s string) string {
 	return ip
 }
 
+func PortPart(s string) (int, error) {
+	// Must be IP:port
+	_, port, err := net.SplitHostPort(s)
+	if err != nil {
+		glog.Errorf("Error parsing '%s': %v", s, err)
+		return -1, err
+	}
+	portNumber, err := strconv.Atoi(port)
+	if err != nil {
+		glog.Errorf("Error parsing '%s': %v", port, err)
+		return -1, err
+	}
+	return portNumber, nil
+}
+
 // ToCIDR returns a host address of the form <ip-address>/32 for
 // IPv4 and <ip-address>/128 for IPv6
 func ToCIDR(ip net.IP) string {