controller.go

package plugin

import (
	"fmt"
	"io/ioutil"
	"net"
	"strings"
	"time"

	"github.com/golang/glog"

	osapi "github.com/openshift/origin/pkg/sdn/api"
	"github.com/openshift/origin/pkg/util/ipcmd"
	"github.com/openshift/origin/pkg/util/netutils"
	"github.com/openshift/origin/pkg/util/ovs"

	kapi "k8s.io/kubernetes/pkg/api"
	kapierrs "k8s.io/kubernetes/pkg/api/errors"
	kexec "k8s.io/kubernetes/pkg/util/exec"
	utilruntime "k8s.io/kubernetes/pkg/util/runtime"
	"k8s.io/kubernetes/pkg/util/sysctl"
	utilwait "k8s.io/kubernetes/pkg/util/wait"
	"k8s.io/kubernetes/pkg/watch"
)

const (
	// rule versioning; increment each time flow rules change
	VERSION        = 1
	VERSION_TABLE  = "table=253"
	VERSION_ACTION = "actions=note:"

	BR       = "br0"
	LBR      = "lbr0"
	TUN      = "tun0"
	VLINUXBR = "vlinuxbr"
	VOVSBR   = "vovsbr"
	VXLAN    = "vxlan0"

	VXLAN_PORT = "4789"

	EgressNetworkPolicyFailureLabel = "network.openshift.io/not-enforcing-egress-network-policy"
)

func getPluginVersion(multitenant bool) []string {
	if VERSION > 254 {
		panic("Version too large!")
	}
	version := fmt.Sprintf("%02X", VERSION)
	if multitenant {
		return []string{"01", version}
	}
	// single-tenant
	return []string{"00", version}
}

func alreadySetUp(multitenant bool, localSubnetGatewayCIDR, clusterNetworkCIDR string) bool {
	var found bool

	exec := kexec.New()
	itx := ipcmd.NewTransaction(exec, LBR)
	addrs, err := itx.GetAddresses()
	itx.EndTransaction()
	if err != nil {
		return false
	}
	found = false
	for _, addr := range addrs {
		if addr == localSubnetGatewayCIDR {
			found = true
			break
		}
	}
	if !found {
		return false
	}
	itx = ipcmd.NewTransaction(exec, TUN)
	routes, err := itx.GetRoutes()
	itx.EndTransaction()
	if err != nil {
		return false
	}
	found = false
	for _, route := range routes {
		if strings.Contains(route, clusterNetworkCIDR+" ") {
			found = true
			break
		}
	}
	if !found {
		return false
	}

	otx := ovs.NewTransaction(exec, BR)
	flows, err := otx.DumpFlows()
	otx.EndTransaction()
	if err != nil {
		return false
	}
	found = false
	for _, flow := range flows {
		if !strings.Contains(flow, VERSION_TABLE) {
			continue
		}
		idx := strings.Index(flow, VERSION_ACTION)
		if idx < 0 {
			continue
		}

		// OVS note action format hex bytes separated by '.'; first
		// byte is plugin type (multi-tenant/single-tenant) and second
		// byte is flow rule version
		expected := getPluginVersion(multitenant)
		existing := strings.Split(flow[idx+len(VERSION_ACTION):], ".")
		if len(existing) >= 2 && existing[0] == expected[0] && existing[1] == expected[1] {
			found = true
			break
		}
	}
	if !found {
		return false
	}

	return true
}

func deleteLocalSubnetRoute(device, localSubnetCIDR string) {
	const (
		timeInterval = 100 * time.Millisecond
		maxIntervals = 20
	)

	for i := 0; i < maxIntervals; i++ {
		itx := ipcmd.NewTransaction(kexec.New(), device)
		routes, err := itx.GetRoutes()
		if err != nil {
			glog.Errorf("Could not get routes for dev %s: %v", device, err)
			return
		}
		for _, route := range routes {
			if strings.Contains(route, localSubnetCIDR) {
				itx.DeleteRoute(localSubnetCIDR)
				err = itx.EndTransaction()
				if err != nil {
					glog.Errorf("Could not delete subnet route %s from dev %s: %v", localSubnetCIDR, device, err)
				}
				return
			}
		}

		time.Sleep(timeInterval)
	}

	glog.Errorf("Timed out looking for %s route for dev %s; if it appears later it will not be deleted.", localSubnetCIDR, device)
}

func (plugin *OsdnNode) SetupSDN(localSubnetCIDR, clusterNetworkCIDR, servicesNetworkCIDR string, mtu uint32) (bool, error) {
	_, ipnet, err := net.ParseCIDR(localSubnetCIDR)
	localSubnetMaskLength, _ := ipnet.Mask.Size()
	localSubnetGateway := netutils.GenerateDefaultGateway(ipnet).String()

	glog.V(5).Infof("[SDN setup] node pod subnet %s gateway %s", ipnet.String(), localSubnetGateway)

	gwCIDR := fmt.Sprintf("%s/%d", localSubnetGateway, localSubnetMaskLength)
	if alreadySetUp(plugin.multitenant, gwCIDR, clusterNetworkCIDR) {
		glog.V(5).Infof("[SDN setup] no SDN setup required")
		return false, nil
	}
	glog.V(5).Infof("[SDN setup] full SDN setup required")

	mtuStr := fmt.Sprint(mtu)

	exec := kexec.New()
	itx := ipcmd.NewTransaction(exec, LBR)
	itx.SetLink("down")
	itx.IgnoreError()
	itx.DeleteLink()
	itx.IgnoreError()
	itx.AddLink("type", "bridge")
	itx.AddAddress(gwCIDR)
	itx.SetLink("up")
	err = itx.EndTransaction()
	if err != nil {
		glog.Errorf("Failed to configure docker bridge: %v", err)
		return false, err
	}
	defer deleteLocalSubnetRoute(LBR, localSubnetCIDR)

	glog.V(5).Infof("[SDN setup] docker setup %s mtu %s", LBR, mtuStr)
	out, err := exec.Command("openshift-sdn-docker-setup.sh", LBR, mtuStr).CombinedOutput()
	if err != nil {
		glog.Errorf("Failed to configure docker networking: %v\n%s", err, out)
		return false, err
	} else {
		glog.V(5).Infof("[SDN setup] docker setup success:\n%s", out)
	}

	config := fmt.Sprintf("export OPENSHIFT_CLUSTER_SUBNET=%s", clusterNetworkCIDR)
	err = ioutil.WriteFile("/run/openshift-sdn/config.env", []byte(config), 0644)
	if err != nil {
		return false, err
	}

	itx = ipcmd.NewTransaction(exec, VLINUXBR)
	itx.DeleteLink()
	itx.IgnoreError()
	itx.AddLink("mtu", mtuStr, "type", "veth", "peer", "name", VOVSBR, "mtu", mtuStr)
	itx.SetLink("up")
	itx.SetLink("txqueuelen", "0")
	err = itx.EndTransaction()
	if err != nil {
		return false, err
	}

	itx = ipcmd.NewTransaction(exec, VOVSBR)
	itx.SetLink("up")
	itx.SetLink("txqueuelen", "0")
	err = itx.EndTransaction()
	if err != nil {
		return false, err
	}

	itx = ipcmd.NewTransaction(exec, LBR)
	itx.AddSlave(VLINUXBR)
	err = itx.EndTransaction()
	if err != nil {
		return false, err
	}

	otx := ovs.NewTransaction(exec, BR)
	otx.AddBridge("fail-mode=secure", "protocols=OpenFlow13")
	otx.AddPort(VXLAN, 1, "type=vxlan", `options:remote_ip="flow"`, `options:key="flow"`)
	otx.AddPort(TUN, 2, "type=internal")
	otx.AddPort(VOVSBR, 3)

	// Table 0: initial dispatch based on in_port
	// vxlan0
	otx.AddFlow("table=0, priority=200, in_port=1, arp, nw_src=%s, nw_dst=%s, actions=move:NXM_NX_TUN_ID[0..31]->NXM_NX_REG0[],goto_table:1", clusterNetworkCIDR, localSubnetCIDR)
	otx.AddFlow("table=0, priority=200, in_port=1, ip, nw_src=%s, nw_dst=%s, actions=move:NXM_NX_TUN_ID[0..31]->NXM_NX_REG0[],goto_table:1", clusterNetworkCIDR, localSubnetCIDR)
	otx.AddFlow("table=0, priority=150, in_port=1, actions=drop")
	// tun0
	otx.AddFlow("table=0, priority=200, in_port=2, arp, nw_src=%s, nw_dst=%s, actions=goto_table:5", localSubnetGateway, clusterNetworkCIDR)
	otx.AddFlow("table=0, priority=200, in_port=2, ip, actions=goto_table:5")
	otx.AddFlow("table=0, priority=150, in_port=2, actions=drop")
	// vovsbr
	otx.AddFlow("table=0, priority=200, in_port=3, arp, nw_src=%s, actions=goto_table:5", localSubnetCIDR)
	otx.AddFlow("table=0, priority=200, in_port=3, ip, nw_src=%s, actions=goto_table:5", localSubnetCIDR)
	otx.AddFlow("table=0, priority=150, in_port=3, actions=drop")
	// else, from a container
	otx.AddFlow("table=0, priority=100, arp, actions=goto_table:2")
	otx.AddFlow("table=0, priority=100, ip, actions=goto_table:2")
	otx.AddFlow("table=0, priority=0, actions=drop")

	// Table 1: VXLAN ingress filtering; filled in by AddHostSubnetRules()
	// eg, "table=1, priority=100, tun_src=${remote_node_ip}, actions=goto_table:5"
	otx.AddFlow("table=1, priority=0, actions=drop")

	// Table 2: from OpenShift container; validate IP/MAC, assign tenant-id; filled in by openshift-sdn-ovs
	// eg, "table=2, priority=100, in_port=${ovs_port}, arp, nw_src=${ipaddr}, arp_sha=${macaddr}, actions=load:${tenant_id}->NXM_NX_REG0[], goto_table:5"
	//     "table=2, priority=100, in_port=${ovs_port}, ip, nw_src=${ipaddr}, actions=load:${tenant_id}->NXM_NX_REG0[], goto_table:3"
	// (${tenant_id} is always 0 for single-tenant)
	otx.AddFlow("table=2, priority=0, actions=drop")

	// Table 3: from OpenShift container; service vs non-service
	otx.AddFlow("table=3, priority=100, ip, nw_dst=%s, actions=goto_table:4", servicesNetworkCIDR)
	otx.AddFlow("table=3, priority=0, actions=goto_table:5")

	// Table 4: from OpenShift container; service dispatch; filled in by AddServiceRules()
	otx.AddFlow("table=4, priority=200, reg0=0, actions=output:2")
	// eg, "table=4, priority=100, reg0=${tenant_id}, ${service_proto}, nw_dst=${service_ip}, tp_dst=${service_port}, actions=output:2"
	otx.AddFlow("table=4, priority=0, actions=drop")

	// Table 5: general routing
	otx.AddFlow("table=5, priority=300, arp, nw_dst=%s, actions=output:2", localSubnetGateway)
	otx.AddFlow("table=5, priority=300, ip, nw_dst=%s, actions=output:2", localSubnetGateway)
	otx.AddFlow("table=5, priority=200, arp, nw_dst=%s, actions=goto_table:6", localSubnetCIDR)
	otx.AddFlow("table=5, priority=200, ip, nw_dst=%s, actions=goto_table:7", localSubnetCIDR)
	otx.AddFlow("table=5, priority=100, arp, nw_dst=%s, actions=goto_table:8", clusterNetworkCIDR)
	otx.AddFlow("table=5, priority=100, ip, nw_dst=%s, actions=goto_table:8", clusterNetworkCIDR)
	otx.AddFlow("table=5, priority=0, ip, actions=goto_table:9")
	otx.AddFlow("table=5, priority=0, arp, actions=drop")

	// Table 6: ARP to container, filled in by openshift-sdn-ovs
	// eg, "table=6, priority=100, arp, nw_dst=${container_ip}, actions=output:${ovs_port}"
	otx.AddFlow("table=6, priority=0, actions=output:3")

	// Table 7: IP to container; filled in by openshift-sdn-ovs
	// eg, "table=7, priority=100, reg0=0, ip, nw_dst=${ipaddr}, actions=output:${ovs_port}"
	// eg, "table=7, priority=100, reg0=${tenant_id}, ip, nw_dst=${ipaddr}, actions=output:${ovs_port}"
	otx.AddFlow("table=7, priority=0, actions=output:3")

	// Table 8: to remote container; filled in by AddHostSubnetRules()
	// eg, "table=8, priority=100, arp, nw_dst=${remote_subnet_cidr}, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31], set_field:${remote_node_ip}->tun_dst,output:1"
	// eg, "table=8, priority=100, ip, nw_dst=${remote_subnet_cidr}, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31], set_field:${remote_node_ip}->tun_dst,output:1"
	otx.AddFlow("table=8, priority=0, actions=drop")

	// Table 9: egress network policy dispatch; edited by updateEgressNetworkPolicy()
	// eg, "table=9, reg0=${tenant_id}, priority=2, ip, nw_dst=${external_cidr}, actions=drop
	otx.AddFlow("table=9, priority=0, actions=output:2")

	err = otx.EndTransaction()
	if err != nil {
		return false, err
	}

	itx = ipcmd.NewTransaction(exec, TUN)
	itx.AddAddress(gwCIDR)
	defer deleteLocalSubnetRoute(TUN, localSubnetCIDR)
	itx.SetLink("mtu", mtuStr)
	itx.SetLink("up")
	itx.AddRoute(clusterNetworkCIDR, "proto", "kernel", "scope", "link")
	itx.AddRoute(servicesNetworkCIDR)
	err = itx.EndTransaction()
	if err != nil {
		return false, err
	}

	// Clean up docker0 since docker won't
	itx = ipcmd.NewTransaction(exec, "docker0")
	itx.SetLink("down")
	itx.IgnoreError()
	itx.DeleteLink()
	itx.IgnoreError()
	_ = itx.EndTransaction()

	sysctl := sysctl.New()

	// Disable iptables for linux bridges (and in particular lbr0), ignoring errors.
	// (This has to have been performed in advance for docker-in-docker deployments,
	// since this will fail there).
	_, _ = exec.Command("modprobe", "br_netfilter").CombinedOutput()
	err = sysctl.SetSysctl("net/bridge/bridge-nf-call-iptables", 0)
	if err != nil {
		glog.Warningf("Could not set net.bridge.bridge-nf-call-iptables sysctl: %s", err)
	} else {
		glog.V(5).Infof("[SDN setup] set net.bridge.bridge-nf-call-iptables to 0")
	}

	// Enable IP forwarding for ipv4 packets
	err = sysctl.SetSysctl("net/ipv4/ip_forward", 1)
	if err != nil {
		return false, fmt.Errorf("Could not enable IPv4 forwarding: %s", err)
	}
	err = sysctl.SetSysctl(fmt.Sprintf("net/ipv4/conf/%s/forwarding", TUN), 1)
	if err != nil {
		return false, fmt.Errorf("Could not enable IPv4 forwarding on %s: %s", TUN, err)
	}

	// Table 253: rule version; note action is hex bytes separated by '.'
	otx = ovs.NewTransaction(exec, BR)
	pluginVersion := getPluginVersion(plugin.multitenant)
	otx.AddFlow("%s, %s%s.%s", VERSION_TABLE, VERSION_ACTION, pluginVersion[0], pluginVersion[1])
	err = otx.EndTransaction()
	if err != nil {
		return false, err
	}

	return true, nil
}

func (plugin *OsdnNode) updateEgressNetworkPolicyFailureLabel(failure bool) error {
	node, err := plugin.registry.kClient.Nodes().Get(plugin.hostName)
	if err != nil {
		return err
	}
	if failure {
		if node.Labels == nil {
			node.Labels = make(map[string]string)
		}
		node.Labels[EgressNetworkPolicyFailureLabel] = "true"
	} else {
		label, ok := node.Labels[EgressNetworkPolicyFailureLabel]
		if !ok || label != "true" {
			return nil
		}
		delete(node.Labels, EgressNetworkPolicyFailureLabel)
	}

	_, err = plugin.registry.kClient.Nodes().UpdateStatus(node)
	return err
}

func (plugin *OsdnNode) SetupEgressNetworkPolicy() error {
	policies, err := plugin.registry.GetEgressNetworkPolicies()
	if err != nil {
		if kapierrs.IsForbidden(err) {
			// 1.3 node running with 1.2-bootstrapped policies
			glog.Errorf("WARNING: EgressNetworkPolicy is not being enforced - please ensure your nodes have access to view EgressNetworkPolicy (eg, 'oadm policy reconcile-cluster-roles')")
			err := plugin.updateEgressNetworkPolicyFailureLabel(true)
			if err != nil {
				return fmt.Errorf("could not update %q label on Node: %v", EgressNetworkPolicyFailureLabel, err)
			}
			return nil
		}
		return fmt.Errorf("could not get EgressNetworkPolicies: %s", err)
	} else {
		err = plugin.updateEgressNetworkPolicyFailureLabel(false)
		if err != nil {
			glog.Warningf("could not remove %q label on Node: %v", EgressNetworkPolicyFailureLabel, err)
		}
	}

	for _, policy := range policies {
		vnid, err := plugin.vnids.GetVNID(policy.Namespace)
		if err != nil {
			glog.Warningf("Could not find netid for namespace %q: %v", policy.Namespace, err)
			continue
		}
		plugin.egressPolicies[vnid] = append(plugin.egressPolicies[vnid], &policy)
	}

	for vnid := range plugin.egressPolicies {
		err := plugin.updateEgressNetworkPolicy(vnid)
		if err != nil {
			return err
		}
	}

	go utilwait.Forever(plugin.watchEgressNetworkPolicies, 0)
	return nil
}

func (plugin *OsdnNode) watchEgressNetworkPolicies() {
	eventQueue := plugin.registry.RunEventQueue(EgressNetworkPolicies)

	for {
		eventType, obj, err := eventQueue.Pop()
		if err != nil {
			utilruntime.HandleError(fmt.Errorf("EventQueue failed for EgressNetworkPolicy: %v", err))
			return
		}
		policy := obj.(*osapi.EgressNetworkPolicy)

		vnid, err := plugin.vnids.GetVNID(policy.Namespace)
		if err != nil {
			glog.Warningf("Could not find netid for namespace %q: %v", policy.Namespace, err)
			continue
		}

		policies := plugin.egressPolicies[vnid]
		for i, oldPolicy := range policies {
			if oldPolicy.UID == policy.UID {
				policies = append(policies[:i], policies[i+1:]...)
				break
			}
		}
		if eventType != watch.Deleted && len(policy.Spec.Egress) > 0 {
			policies = append(policies, policy)
		}
		plugin.egressPolicies[vnid] = policies

		err = plugin.updateEgressNetworkPolicy(vnid)
		if err != nil {
			utilruntime.HandleError(err)
			return
		}
	}
}

func (plugin *OsdnNode) UpdateEgressNetworkPolicyVNID(namespace string, oldVnid, newVnid uint32) error {
	var policy *osapi.EgressNetworkPolicy

	policies := plugin.egressPolicies[oldVnid]
	for i, oldPolicy := range policies {
		if oldPolicy.Namespace == namespace {
			policy = oldPolicy
			plugin.egressPolicies[oldVnid] = append(policies[:i], policies[i+1:]...)
			err := plugin.updateEgressNetworkPolicy(oldVnid)
			if err != nil {
				return err
			}
			break
		}
	}

	if policy != nil {
		plugin.egressPolicies[newVnid] = append(plugin.egressPolicies[newVnid], policy)
		err := plugin.updateEgressNetworkPolicy(newVnid)
		if err != nil {
			return err
		}
	}

	return nil
}

func policyNames(policies []*osapi.EgressNetworkPolicy) string {
	names := make([]string, len(policies))
	for i, policy := range policies {
		names[i] = policy.Namespace + ":" + policy.Name
	}
	return strings.Join(names, ", ")
}

func (plugin *OsdnNode) updateEgressNetworkPolicy(vnid uint32) error {
	otx := ovs.NewTransaction(kexec.New(), BR)

	policies := plugin.egressPolicies[vnid]
	namespaces := plugin.vnids.GetNamespaces(vnid)
	if len(policies) == 0 {
		otx.DeleteFlows("table=9, reg0=%d", vnid)
	} else if vnid == 0 {
		glog.Errorf("EgressNetworkPolicy in global network namespace is not allowed (%s); ignoring", policyNames(policies))
	} else if len(namespaces) > 1 {
		glog.Errorf("EgressNetworkPolicy not allowed in shared NetNamespace (%s); dropping all traffic", strings.Join(namespaces, ", "))
		otx.DeleteFlows("table=9, reg0=%d", vnid)
		otx.AddFlow("table=9, reg0=%d, priority=1, actions=drop", vnid)
	} else if len(policies) > 1 {
		glog.Errorf("multiple EgressNetworkPolicies in same network namespace (%s) is not allowed; dropping all traffic", policyNames(policies))
		otx.DeleteFlows("table=9, reg0=%d", vnid)
		otx.AddFlow("table=9, reg0=%d, priority=1, actions=drop", vnid)
	} else /* vnid != 0 && len(policies) == 1 */ {
		// Temporarily drop all outgoing traffic, to avoid race conditions while modifying the other rules
		otx.AddFlow("table=9, reg0=%d, cookie=1, priority=65535, actions=drop", vnid)
		otx.DeleteFlows("table=9, reg0=%d, cookie=0/1", vnid)

		for i, rule := range policies[0].Spec.Egress {
			priority := len(policies[0].Spec.Egress) - i

			var action string
			if rule.Type == osapi.EgressNetworkPolicyRuleAllow {
				action = "output:2"
			} else {
				action = "drop"
			}

			var dst string
			if rule.To.CIDRSelector == "0.0.0.0/32" {
				dst = ""
			} else {
				dst = fmt.Sprintf(", nw_dst=%s", rule.To.CIDRSelector)
			}

			otx.AddFlow("table=9, reg0=%d, priority=%d, ip%s, actions=%s", vnid, priority, dst, action)
		}
		otx.DeleteFlows("table=9, reg0=%d, cookie=1/1", vnid)
	}

	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error updating OVS flows for EgressNetworkPolicy: %v", err)
	}
	return nil
}

func (plugin *OsdnNode) AddHostSubnetRules(subnet *osapi.HostSubnet) error {
	glog.Infof("AddHostSubnetRules for %s", hostSubnetToString(subnet))
	otx := ovs.NewTransaction(kexec.New(), BR)

	otx.AddFlow("table=1, priority=100, tun_src=%s, actions=goto_table:5", subnet.HostIP)
	otx.AddFlow("table=8, priority=100, arp, nw_dst=%s, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, subnet.HostIP)
	otx.AddFlow("table=8, priority=100, ip, nw_dst=%s, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, subnet.HostIP)

	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error adding OVS flows for subnet: %v, %v", subnet, err)
	}
	return nil
}

func (plugin *OsdnNode) DeleteHostSubnetRules(subnet *osapi.HostSubnet) error {
	glog.Infof("DeleteHostSubnetRules for %s", hostSubnetToString(subnet))

	otx := ovs.NewTransaction(kexec.New(), BR)
	otx.DeleteFlows("table=1, tun_src=%s", subnet.HostIP)
	otx.DeleteFlows("table=8, ip, nw_dst=%s", subnet.Subnet)
	otx.DeleteFlows("table=8, arp, nw_dst=%s", subnet.Subnet)
	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error deleting OVS flows for subnet: %v, %v", subnet, err)
	}
	return nil
}

func (plugin *OsdnNode) AddServiceRules(service *kapi.Service, netID uint32) error {
	if !plugin.multitenant {
		return nil
	}

	glog.V(5).Infof("AddServiceRules for %v", service)

	otx := ovs.NewTransaction(kexec.New(), BR)
	for _, port := range service.Spec.Ports {
		otx.AddFlow(generateAddServiceRule(netID, service.Spec.ClusterIP, port.Protocol, int(port.Port)))
		err := otx.EndTransaction()
		if err != nil {
			return fmt.Errorf("Error adding OVS flows for service: %v, netid: %d, %v", service, netID, err)
		}
	}
	return nil
}

func (plugin *OsdnNode) DeleteServiceRules(service *kapi.Service) error {
	if !plugin.multitenant {
		return nil
	}

	glog.V(5).Infof("DeleteServiceRules for %v", service)

	otx := ovs.NewTransaction(kexec.New(), BR)
	for _, port := range service.Spec.Ports {
		otx.DeleteFlows(generateDeleteServiceRule(service.Spec.ClusterIP, port.Protocol, int(port.Port)))
		err := otx.EndTransaction()
		if err != nil {
			return fmt.Errorf("Error deleting OVS flows for service: %v, %v", service, err)
		}
	}
	return nil
}

func generateBaseServiceRule(IP string, protocol kapi.Protocol, port int) string {
	return fmt.Sprintf("table=4, %s, nw_dst=%s, tp_dst=%d", strings.ToLower(string(protocol)), IP, port)
}

func generateAddServiceRule(netID uint32, IP string, protocol kapi.Protocol, port int) string {
	baseRule := generateBaseServiceRule(IP, protocol, port)
	if netID == 0 {
		return fmt.Sprintf("%s, priority=100, actions=output:2", baseRule)
	} else {
		return fmt.Sprintf("%s, priority=100, reg0=%d, actions=output:2", baseRule, netID)
	}
}

func generateDeleteServiceRule(IP string, protocol kapi.Protocol, port int) string {
	return generateBaseServiceRule(IP, protocol, port)
}