apps/routing/cpr/src/main/java/org/onosproject/routing/cpr/ControlPlaneRedirectManager.java

/*
 * Copyright 2017-present Open Networking Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.onosproject.routing.cpr;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.onlab.packet.EthType;
import org.onlab.packet.Ip4Address;
import org.onlab.packet.Ip6Address;
import org.onlab.packet.IpPrefix;
import org.onlab.packet.MacAddress;
import org.onlab.packet.VlanId;
import org.onlab.util.Tools;
import org.onosproject.app.ApplicationService;
import org.onosproject.cfg.ComponentConfigService;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.mastership.MastershipService;
import org.onosproject.net.DeviceId;
import org.onosproject.net.Host;
import org.onosproject.net.PortNumber;
import org.onosproject.net.config.NetworkConfigEvent;
import org.onosproject.net.config.NetworkConfigListener;
import org.onosproject.net.config.NetworkConfigRegistry;
import org.onosproject.net.device.DeviceService;
import org.onosproject.net.flow.DefaultTrafficSelector;
import org.onosproject.net.flow.DefaultTrafficTreatment;
import org.onosproject.net.flow.TrafficSelector;
import org.onosproject.net.flow.TrafficTreatment;
import org.onosproject.net.flowobjective.DefaultForwardingObjective;
import org.onosproject.net.flowobjective.DefaultNextObjective;
import org.onosproject.net.flowobjective.FlowObjectiveService;
import org.onosproject.net.flowobjective.ForwardingObjective;
import org.onosproject.net.flowobjective.NextObjective;
import org.onosproject.net.host.HostService;
import org.onosproject.net.host.InterfaceIpAddress;
import org.onosproject.net.intf.Interface;
import org.onosproject.net.intf.InterfaceService;
import org.onosproject.routing.InterfaceProvisionRequest;
import org.onosproject.routing.Router;
import org.onosproject.routing.RouterInfo;
import org.onosproject.routing.RoutingService;
import org.onosproject.routing.config.RoutersConfig;
import org.onosproject.routing.config.RoutingConfiguration;
import org.osgi.service.component.ComponentContext;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.osgi.service.component.annotations.Modified;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferenceCardinality;
import org.slf4j.Logger;

import java.util.Dictionary;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import static org.onlab.packet.Ethernet.TYPE_ARP;
import static org.onlab.packet.Ethernet.TYPE_IPV4;
import static org.onlab.packet.Ethernet.TYPE_IPV6;
import static org.onlab.packet.ICMP6.NEIGHBOR_ADVERTISEMENT;
import static org.onlab.packet.ICMP6.NEIGHBOR_SOLICITATION;
import static org.onlab.packet.IPv6.PROTOCOL_ICMP6;
import static org.onlab.packet.IPv6.getLinkLocalAddress;
import static org.onlab.packet.IPv6.getSolicitNodeAddress;
import static org.onosproject.routing.cpr.OsgiPropertyConstants.FORCE_UNPROVISION;
import static org.onosproject.routing.cpr.OsgiPropertyConstants.FORCE_UNPROVISION_DEFAULT;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Manages connectivity between peers redirecting control traffic to a routing
 * control plane available on the dataplane.
 */
@Component(
    immediate = true,
    property = {
        FORCE_UNPROVISION + ":Boolean=" + FORCE_UNPROVISION_DEFAULT
    }
)
public class ControlPlaneRedirectManager {

    private final Logger log = getLogger(getClass());

    public static final short ASSIGNED_VLAN = 4094;

    private static final int MIN_IP_PRIORITY = 10;
    private static final int IPV4_PRIORITY = 2000;
    private static final int IPV6_PRIORITY = 500;
    static final int ACL_PRIORITY = 40001;
    private static final int OSPF_IP_PROTO = 0x59;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected CoreService coreService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected DeviceService deviceService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected InterfaceService interfaceService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected FlowObjectiveService flowObjectiveService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected NetworkConfigRegistry networkConfigService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected MastershipService mastershipService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected HostService hostService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected ApplicationService applicationService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected ComponentConfigService cfgService;

    /** Force unprovision when the device goes offline. */
    private boolean forceUnprovision = FORCE_UNPROVISION_DEFAULT;

    private static final String APP_NAME = "org.onosproject.cpr";
    private ApplicationId appId;

    private Map<Host, Set<Integer>> peerNextId = Maps.newConcurrentMap();

    private Map<DeviceId, Router> routers = new ConcurrentHashMap<>();

    private final InternalNetworkConfigListener networkConfigListener =
            new InternalNetworkConfigListener();

    @Activate
    protected void activate(ComponentContext context) {
        this.appId = coreService.registerApplication(APP_NAME);

        cfgService.registerProperties(getClass());
        modified(context);

        RoutingConfiguration.register(networkConfigService);

        networkConfigService.addListener(networkConfigListener);

        processRouterConfig();

        applicationService.registerDeactivateHook(this.appId,
                () -> routers.forEach((d, r) -> r.cleanup()));
    }

    @Deactivate
    protected void deactivate() {
        cfgService.unregisterProperties(getClass(), false);
        networkConfigService.removeListener(networkConfigListener);
        RoutingConfiguration.unregister(networkConfigService);
    }

    @Modified
    protected void modified(ComponentContext context) {
        if (context != null) {
            readComponentConfiguration(context);
            processRouterConfig();
        }
    }

    private void readComponentConfiguration(ComponentContext context) {
        Dictionary<?, ?> properties = context.getProperties();
        Boolean flag;

        flag = Tools.isPropertyEnabled(properties, FORCE_UNPROVISION);
        if (flag == null) {
            log.info("ForceUnprovision is not configured, " +
                    "using current value of {}", forceUnprovision);
        } else {
            forceUnprovision = flag;
            log.info("Configured. ForceUnprovision is {}",
                    forceUnprovision ? "enabled" : "disabled");
        }
    }

    /**
     * Sets up the router interfaces if router config is available.
     */
    private void processRouterConfig() {
        ApplicationId routingAppId =
                coreService.registerApplication(RoutingService.ROUTER_APP_ID);

        Set<RoutersConfig.Router> routerConfigs =
                RoutingConfiguration.getRouterConfigurations(networkConfigService, routingAppId);

        for (RoutersConfig.Router router : routerConfigs) {
            DeviceId deviceId = router.controlPlaneConnectPoint().deviceId();

            routers.compute(deviceId, (d, r) -> {
                if (r == null) {
                    return createRouter(RouterInfo.from(router));
                } else {
                    r.changeConfiguration(RouterInfo.from(router), forceUnprovision);
                    return r;
                }
            });
        }

        for (DeviceId deviceId : routers.keySet()) {
            if (!configExists(deviceId, routerConfigs)) {
                Router router = routers.remove(deviceId);
                router.cleanup();
            }
        }
    }

    private boolean configExists(DeviceId deviceId, Set<RoutersConfig.Router> config) {
        return config.stream()
                .anyMatch(r -> r.controlPlaneConnectPoint().deviceId().equals(deviceId));
    }

    private Router createRouter(RouterInfo info) {
        return new Router(info,
                interfaceService,
                deviceService,
                this::provisionInterface,
                this::unprovisionInterface,
                forceUnprovision);
    }

    private void provisionInterface(InterfaceProvisionRequest intf) {
        updateInterfaceObjectives(intf, true);
    }

    private void unprovisionInterface(InterfaceProvisionRequest intf) {
        updateInterfaceObjectives(intf, false);
    }

    /**
     * Installs or removes flow objectives relating to a give interface.
     *
     * @param intf interface to change objectives for
     * @param install true to install the objectives, false to remove them
     */
    private void updateInterfaceObjectives(InterfaceProvisionRequest intf, boolean install) {
        updateInterfaceForwarding(intf, install);
        updateOspfForwarding(intf, install);
    }

    /**
     * Installs or removes the basic forwarding flows for each interface.
     *
     * @param request provisioning request containing router and interface
     * @param install true to install the objectives, false to remove them
     */
    private void updateInterfaceForwarding(InterfaceProvisionRequest request, boolean install) {
        Interface intf = request.intf();
        log.debug("{} interface objectives for {}", operation(install), intf);

        DeviceId deviceId = intf.connectPoint().deviceId();

        PortNumber controlPlanePort = request.controlPlaneConnectPoint().port();
        for (InterfaceIpAddress ip : intf.ipAddressesList()) {
            // create nextObjectives for forwarding to this interface and the
            // controlPlaneConnectPoint
            int cpNextId, intfNextId;
            if (intf.vlan() == VlanId.NONE) {
                cpNextId = modifyNextObjective(deviceId, controlPlanePort,
                               VlanId.vlanId(ASSIGNED_VLAN),
                               true, install);
                intfNextId = modifyNextObjective(deviceId, intf.connectPoint().port(),
                               VlanId.vlanId(ASSIGNED_VLAN),
                               true, install);
            } else {
                cpNextId = modifyNextObjective(deviceId, controlPlanePort,
                                               intf.vlan(), false, install);
                intfNextId = modifyNextObjective(deviceId, intf.connectPoint().port(),
                                                 intf.vlan(), false, install);
            }
            List<ForwardingObjective> fwdToSend = Lists.newArrayList();
            TrafficSelector selector;
            // IP traffic toward the router.
            selector = buildIPDstSelector(
                    ip.ipAddress().toIpPrefix(),
                    intf.connectPoint().port(),
                    null,
                    intf.mac(),
                    intf.vlan()
            );
            fwdToSend.add(buildForwardingObjective(selector, null, cpNextId, install, ACL_PRIORITY));
            // IP traffic from the router.
            selector = buildIPSrcSelector(
                    ip.ipAddress().toIpPrefix(),
                    controlPlanePort,
                    intf.mac(),
                    null,
                    intf.vlan()
            );
            fwdToSend.add(buildForwardingObjective(selector, null, intfNextId, install, ACL_PRIORITY));
            // We build the punt treatment.
            TrafficTreatment treatment = DefaultTrafficTreatment.builder()
                    .punt()
                    .build();
            // Handling of neighbour discovery protocols.
            // IPv4 traffic - we have to deal with the ARP protocol.
            // IPv6 traffic - we have to deal with the NDP protocol.
            if (ip.ipAddress().isIp4()) {
                 // ARP traffic towards the router.
                selector = buildArpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // ARP traffic from the router.
                selector = buildArpSelector(
                        controlPlanePort,
                        intf.vlan(),
                        ip.ipAddress().getIp4Address(),
                        intf.mac()
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, intfNextId, install, ACL_PRIORITY + 1));
            } else {
                // Neighbour solicitation traffic towards the router.
                // This flow is for the global unicast address.
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        ip.ipAddress().toIpPrefix(),
                        NEIGHBOR_SOLICITATION,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour solicitation traffic towards the router.
                // This flow is for the link local address.
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        Ip6Address.valueOf(getLinkLocalAddress(intf.mac().toBytes())).toIpPrefix(),
                        NEIGHBOR_SOLICITATION,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour solicitation traffic towards the router.
                // This flow is for the solicitation node address of
                // the global unicast address.
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        Ip6Address.valueOf(getSolicitNodeAddress(ip.ipAddress().toOctets())).toIpPrefix(),
                        NEIGHBOR_SOLICITATION,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour solicitation traffic towards the router.
                // This flow is for the solicitation node address of
                // the link local address.
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        Ip6Address.valueOf(
                                getSolicitNodeAddress(getLinkLocalAddress(intf.mac().toBytes()))
                        ).toIpPrefix(),
                        NEIGHBOR_SOLICITATION,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour solicitation traffic from the router.
                // This flow is for the global unicast address.
                selector = buildNdpSelector(
                        controlPlanePort,
                        intf.vlan(),
                        ip.ipAddress().toIpPrefix(),
                        null,
                        NEIGHBOR_SOLICITATION,
                        intf.mac()
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, intfNextId, install, ACL_PRIORITY + 1));
                // Neighbour solicitation traffic from the router.
                // This flow is for the link local address.
                selector = buildNdpSelector(
                        controlPlanePort,
                        intf.vlan(),
                        Ip6Address.valueOf(getLinkLocalAddress(intf.mac().toBytes())).toIpPrefix(),
                        null,
                        NEIGHBOR_SOLICITATION,
                        intf.mac()
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, intfNextId, install, ACL_PRIORITY + 1));
                // Neighbour advertisement traffic towards the router.
                // This flow is for the global unicast address
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        ip.ipAddress().toIpPrefix(),
                        NEIGHBOR_ADVERTISEMENT,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour advertisement traffic towards the router.
                // This flow is for the link local address
                selector = buildNdpSelector(
                        intf.connectPoint().port(),
                        intf.vlan(),
                        null,
                        Ip6Address.valueOf(getLinkLocalAddress(intf.mac().toBytes())).toIpPrefix(),
                        NEIGHBOR_ADVERTISEMENT,
                        null
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, cpNextId, install, ACL_PRIORITY + 1));
                // Neighbour advertisement traffic from the router.
                // This flow is for the global unicast address
                selector = buildNdpSelector(
                        controlPlanePort,
                        intf.vlan(),
                        ip.ipAddress().toIpPrefix(),
                        null,
                        NEIGHBOR_ADVERTISEMENT,
                        intf.mac()
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, intfNextId, install, ACL_PRIORITY + 1));
                // Neighbour advertisement traffic from the router.
                // This flow is for the link local address
                selector = buildNdpSelector(
                        controlPlanePort,
                        intf.vlan(),
                        Ip6Address.valueOf(getLinkLocalAddress(intf.mac().toBytes())).toIpPrefix(),
                        null,
                        NEIGHBOR_ADVERTISEMENT,
                        intf.mac()
                );
                fwdToSend.add(buildForwardingObjective(selector, treatment, intfNextId, install, ACL_PRIORITY + 1));
            }
            // Finally we push the fwd objectives through the flow objective service.
            fwdToSend.stream().forEach(forwardingObjective ->
                flowObjectiveService.forward(deviceId, forwardingObjective)
            );
        }
    }

    /**
     * Installs or removes OSPF forwarding rules.
     *
     * @param request provisioning request containing router and interface
     * @param install true to create an add objective, false to create a remove
     *            objective
     */
    private void updateOspfForwarding(InterfaceProvisionRequest request, boolean install) {
        // TODO IPv6 support has not been implemented yet
        Interface intf = request.intf();
        log.debug("{} OSPF flows for {}", operation(install), intf);

        // OSPF to router
        TrafficSelector toSelector = DefaultTrafficSelector.builder()
                .matchInPort(intf.connectPoint().port())
                .matchEthType(EthType.EtherType.IPV4.ethType().toShort())
                .matchVlanId(intf.vlan())
                .matchIPProtocol((byte) OSPF_IP_PROTO)
                .build();

        // create nextObjectives for forwarding to the controlPlaneConnectPoint
        DeviceId deviceId = intf.connectPoint().deviceId();
        PortNumber controlPlanePort = request.controlPlaneConnectPoint().port();
        int cpNextId;
        if (intf.vlan() == VlanId.NONE) {
            cpNextId = modifyNextObjective(deviceId, controlPlanePort,
                           VlanId.vlanId(ASSIGNED_VLAN),
                           true, install);
        } else {
            cpNextId = modifyNextObjective(deviceId, controlPlanePort,
                                           intf.vlan(), false, install);
        }
        flowObjectiveService.forward(intf.connectPoint().deviceId(),
                buildForwardingObjective(toSelector, null, cpNextId,
                        install ? request.info().ospfEnabled() : install, ACL_PRIORITY));
    }

    /**
     * Creates a next objective for forwarding to a port. Handles metadata for
     * some pipelines that require vlan information for egress port.
     *
     * @param deviceId the device on which the next objective is being created
     * @param portNumber the egress port
     * @param vlanId vlan information for egress port
     * @param popVlan if vlan tag should be popped or not
     * @param install true to create an add next objective, false to create a remove
     *            next objective
     * @return nextId of the next objective created
     */
    private int modifyNextObjective(DeviceId deviceId, PortNumber portNumber,
                                    VlanId vlanId, boolean popVlan, boolean install) {
        int nextId = flowObjectiveService.allocateNextId();
        NextObjective.Builder nextObjBuilder = DefaultNextObjective
                .builder().withId(nextId)
                .withType(NextObjective.Type.SIMPLE)
                .fromApp(appId);

        TrafficTreatment.Builder ttBuilder = DefaultTrafficTreatment.builder();
        if (popVlan) {
            ttBuilder.popVlan();
        }
        ttBuilder.setOutput(portNumber);

        // setup metadata to pass to nextObjective - indicate the vlan on egress
        // if needed by the switch pipeline.
        TrafficSelector.Builder metabuilder = DefaultTrafficSelector.builder();
        metabuilder.matchVlanId(vlanId);

        nextObjBuilder.withMeta(metabuilder.build());
        nextObjBuilder.addTreatment(ttBuilder.build());
        log.debug("Submitted next objective {} in device {} for port/vlan {}/{}",
                nextId, deviceId, portNumber, vlanId);
        if (install) {
             flowObjectiveService.next(deviceId, nextObjBuilder.add());
        } else {
             flowObjectiveService.next(deviceId, nextObjBuilder.remove());
        }
        return nextId;
    }

    /**
     * Builds a forwarding objective from the given selector, treatment and nextId.
     *
     * @param selector selector
     * @param treatment treatment to apply to packet, can be null
     * @param nextId next objective to point to for forwarding packet
     * @param add true to create an add objective, false to create a remove
     *            objective
     * @return forwarding objective
     */
    private ForwardingObjective buildForwardingObjective(TrafficSelector selector,
                                                         TrafficTreatment treatment,
                                                         int nextId,
                                                         boolean add,
                                                         int priority) {
        DefaultForwardingObjective.Builder fobBuilder = DefaultForwardingObjective.builder();
        fobBuilder.withSelector(selector);
        if (treatment != null) {
            fobBuilder.withTreatment(treatment);
        }
        if (nextId != -1) {
            fobBuilder.nextStep(nextId);
        }
        fobBuilder.fromApp(appId)
            .withPriority(priority)
            .withFlag(ForwardingObjective.Flag.VERSATILE);

        return add ? fobBuilder.add() : fobBuilder.remove();
    }

    static TrafficSelector.Builder buildBaseSelectorBuilder(PortNumber inPort,
                                                            MacAddress srcMac,
                                                            MacAddress dstMac,
                                                            VlanId vlanId) {
        TrafficSelector.Builder selectorBuilder = DefaultTrafficSelector.builder();
        if (inPort != null) {
            selectorBuilder.matchInPort(inPort);
        }
        if (srcMac != null) {
            selectorBuilder.matchEthSrc(srcMac);
        }
        if (dstMac != null) {
            selectorBuilder.matchEthDst(dstMac);
        }
        if (vlanId != null) {
            selectorBuilder.matchVlanId(vlanId);
        }
        return selectorBuilder;
    }

    static TrafficSelector buildIPDstSelector(IpPrefix dstIp,
                                              PortNumber inPort,
                                              MacAddress srcMac,
                                              MacAddress dstMac,
                                              VlanId vlanId) {
        TrafficSelector.Builder selector = buildBaseSelectorBuilder(inPort, srcMac, dstMac, vlanId);
        if (dstIp.isIp4()) {
            selector.matchEthType(TYPE_IPV4);
            selector.matchIPDst(dstIp);
        } else {
            selector.matchEthType(TYPE_IPV6);
            selector.matchIPv6Dst(dstIp);
        }
        return selector.build();
    }

    static TrafficSelector buildIPSrcSelector(IpPrefix srcIp,
                                              PortNumber inPort,
                                              MacAddress srcMac,
                                              MacAddress dstMac,
                                              VlanId vlanId) {
        TrafficSelector.Builder selector = buildBaseSelectorBuilder(inPort, srcMac, dstMac, vlanId);
        if (srcIp.isIp4()) {
            selector.matchEthType(TYPE_IPV4);
            selector.matchIPSrc(srcIp);
        } else {
            selector.matchEthType(TYPE_IPV6);
            selector.matchIPv6Src(srcIp);
        }
        return selector.build();
    }

    static TrafficSelector buildArpSelector(PortNumber inPort,
                                            VlanId vlanId,
                                            Ip4Address arpSpa,
                                            MacAddress srcMac) {
        TrafficSelector.Builder selector = buildBaseSelectorBuilder(inPort, null, null, vlanId);
        selector.matchEthType(TYPE_ARP);
        if (arpSpa != null) {
            selector.matchArpSpa(arpSpa);
        }
        if (srcMac != null) {
            selector.matchEthSrc(srcMac);
        }
        return selector.build();
    }

    static TrafficSelector buildNdpSelector(PortNumber inPort,
                                            VlanId vlanId,
                                            IpPrefix srcIp,
                                            IpPrefix dstIp,
                                            byte subProto,
                                            MacAddress srcMac) {
        TrafficSelector.Builder selector = buildBaseSelectorBuilder(inPort, null, null, vlanId);
        selector.matchEthType(TYPE_IPV6)
                .matchIPProtocol(PROTOCOL_ICMP6)
                .matchIcmpv6Type(subProto);
        if (srcIp != null) {
            selector.matchIPv6Src(srcIp);
        }
        if (dstIp != null) {
            selector.matchIPv6Dst(dstIp);
        }
        if (srcMac != null) {
            selector.matchEthSrc(srcMac);
        }
        return selector.build();
    }

    private String operation(boolean install) {
        return install ? "Installing" : "Removing";
    }

    /**
     * Listener for network config events.
     */
    private class InternalNetworkConfigListener implements NetworkConfigListener {
        @Override
        public void event(NetworkConfigEvent event) {
            if (event.configClass().equals(RoutingService.ROUTER_CONFIG_CLASS) ||
                    event.configClass().equals(RoutersConfig.class)) {
                switch (event.type()) {
                    case CONFIG_ADDED:
                    case CONFIG_UPDATED:
                    case CONFIG_REMOVED:
                        processRouterConfig();
                        break;
                    case CONFIG_REGISTERED:
                    case CONFIG_UNREGISTERED:
                        break;
                default:
                    break;
                }
            }
        }
    }
}