src/main/java/net/onrc/onos/ofcontroller/proxyarp/ProxyArpManager.java

package net.onrc.onos.ofcontroller.proxyarp;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;

import net.floodlightcontroller.core.FloodlightContext;
import net.floodlightcontroller.core.IFloodlightProviderService;
import net.floodlightcontroller.core.IOFMessageListener;
import net.floodlightcontroller.core.IOFSwitch;
import net.floodlightcontroller.core.module.FloodlightModuleContext;
import net.floodlightcontroller.core.module.IFloodlightModule;
import net.floodlightcontroller.core.module.IFloodlightService;
import net.floodlightcontroller.restserver.IRestApiService;
import net.floodlightcontroller.util.MACAddress;
import net.onrc.onos.datagrid.IDatagridService;
import net.onrc.onos.ofcontroller.bgproute.Interface;
import net.onrc.onos.ofcontroller.core.config.IConfigInfoService;
import net.onrc.onos.ofcontroller.flowprogrammer.IFlowPusherService;
import net.onrc.onos.ofcontroller.util.SwitchPort;
import net.onrc.onos.packet.ARP;
import net.onrc.onos.packet.Ethernet;
import net.onrc.onos.packet.IPv4;

import org.openflow.protocol.OFMessage;
import org.openflow.protocol.OFPacketIn;
import org.openflow.protocol.OFPacketOut;
import org.openflow.protocol.OFPort;
import org.openflow.protocol.OFType;
import org.openflow.protocol.action.OFAction;
import org.openflow.protocol.action.OFActionOutput;
import org.openflow.util.HexString;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimaps;
import com.google.common.collect.SetMultimap;

public class ProxyArpManager implements IProxyArpService, IOFMessageListener,
        IPacketOutEventHandler, IArpReplyEventHandler, IFloodlightModule {
    private static final Logger log = LoggerFactory
            .getLogger(ProxyArpManager.class);

    private static final long ARP_TIMER_PERIOD = 100; // ms

    private static final int ARP_REQUEST_TIMEOUT = 2000; // ms

    private IFloodlightProviderService floodlightProvider;
    private IDatagridService datagrid;
    private IConfigInfoService configService;
    private IRestApiService restApi;
    private IFlowPusherService flowPusher;

    private short vlan;
    private static final short NO_VLAN = 0;

    private SetMultimap<InetAddress, ArpRequest> arpRequests;

    private static class ArpRequest {
        private final IArpRequester requester;
        private final boolean retry;
        private boolean sent = false;
        private long requestTime;

        public ArpRequest(IArpRequester requester, boolean retry) {
            this.requester = requester;
            this.retry = retry;
        }

        public ArpRequest(ArpRequest old) {
            this.requester = old.requester;
            this.retry = old.retry;
        }

        public boolean isExpired() {
            return sent
                    && ((System.currentTimeMillis() - requestTime) > ARP_REQUEST_TIMEOUT);
        }

        public boolean shouldRetry() {
            return retry;
        }

        public void dispatchReply(InetAddress ipAddress,
                MACAddress replyMacAddress) {
            requester.arpResponse(ipAddress, replyMacAddress);
        }

        public void setRequestTime() {
            this.requestTime = System.currentTimeMillis();
            this.sent = true;
        }
    }

    private class HostArpRequester implements IArpRequester {
        private final ARP arpRequest;
        private final long dpid;
        private final short port;

        public HostArpRequester(ARP arpRequest, long dpid, short port) {
            this.arpRequest = arpRequest;
            this.dpid = dpid;
            this.port = port;
        }

        @Override
        public void arpResponse(InetAddress ipAddress, MACAddress macAddress) {
            ProxyArpManager.this.sendArpReply(arpRequest, dpid, port,
                    macAddress);
        }
    }

    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleServices() {
        Collection<Class<? extends IFloodlightService>> l =
                new ArrayList<Class<? extends IFloodlightService>>();
        l.add(IProxyArpService.class);
        return l;
    }

    @Override
    public Map<Class<? extends IFloodlightService>, IFloodlightService> getServiceImpls() {
        Map<Class<? extends IFloodlightService>, IFloodlightService> m =
                new HashMap<Class<? extends IFloodlightService>, IFloodlightService>();
        m.put(IProxyArpService.class, this);
        return m;
    }

    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleDependencies() {
        Collection<Class<? extends IFloodlightService>> dependencies =
                new ArrayList<Class<? extends IFloodlightService>>();
        dependencies.add(IFloodlightProviderService.class);
        dependencies.add(IRestApiService.class);
        dependencies.add(IDatagridService.class);
        dependencies.add(IConfigInfoService.class);
        dependencies.add(IFlowPusherService.class);
        return dependencies;
    }

    @Override
    public void init(FloodlightModuleContext context) {
        this.floodlightProvider = context
                .getServiceImpl(IFloodlightProviderService.class);
        this.datagrid = context.getServiceImpl(IDatagridService.class);
        this.configService = context.getServiceImpl(IConfigInfoService.class);
        this.restApi = context.getServiceImpl(IRestApiService.class);
        this.flowPusher = context.getServiceImpl(IFlowPusherService.class);

        // arpCache = new ArpCache();

        arpRequests = Multimaps.synchronizedSetMultimap(HashMultimap
                .<InetAddress, ArpRequest>create());

    }

    @Override
    public void startUp(FloodlightModuleContext context) {
        this.vlan = configService.getVlan();
        log.info("vlan set to {}", this.vlan);

        restApi.addRestletRoutable(new ArpWebRoutable());
        floodlightProvider.addOFMessageListener(OFType.PACKET_IN, this);

        datagrid.registerPacketOutEventHandler(this);
        datagrid.registerArpReplyEventHandler(this);

        Timer arpTimer = new Timer("arp-processing");
        arpTimer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                doPeriodicArpProcessing();
            }
        }, 0, ARP_TIMER_PERIOD);
    }

    /*
     * Function that runs periodically to manage the asynchronous request mechanism.
     * It basically cleans up old ARP requests if we don't get a response for them.
     * The caller can designate that a request should be retried indefinitely, and
     * this task will handle that as well.
     */
    private void doPeriodicArpProcessing() {
        SetMultimap<InetAddress, ArpRequest> retryList = HashMultimap
                .<InetAddress, ArpRequest>create();

        // Have to synchronize externally on the Multimap while using an
        // iterator,
        // even though it's a synchronizedMultimap
        synchronized (arpRequests) {
            Iterator<Map.Entry<InetAddress, ArpRequest>> it = arpRequests
                    .entries().iterator();

            while (it.hasNext()) {
                Map.Entry<InetAddress, ArpRequest> entry = it.next();
                ArpRequest request = entry.getValue();
                if (request.isExpired()) {
                    log.debug("Cleaning expired ARP request for {}", entry
                            .getKey().getHostAddress());

                    // If the ARP request is expired and then delete the device
                    // TODO check whether this is OK from this thread
                    // TODO: Fix the code below after deviceStorage was removed
                    /*
                    IDeviceObject targetDevice =
                    		deviceStorage.getDeviceByIP(InetAddresses.coerceToInteger(entry.getKey()));
                    if (targetDevice != null) {
                    	deviceStorage.removeDevice(targetDevice);
                    	if (log.isDebugEnabled()) {
                    		log.debug("RemoveDevice: {} due to no have not recieve the ARP reply", targetDevice);
                    	}
                    }
                    */

                    it.remove();

                    if (request.shouldRetry()) {
                        retryList.put(entry.getKey(), request);
                    }
                }
            }
        }

        for (Map.Entry<InetAddress, Collection<ArpRequest>> entry : retryList
                .asMap().entrySet()) {

            InetAddress address = entry.getKey();

            log.debug("Resending ARP request for {}", address.getHostAddress());

            // Only ARP requests sent by the controller will have the retry flag
            // set, so for now we can just send a new ARP request for that
            // address.
            sendArpRequestForAddress(address);

            for (ArpRequest request : entry.getValue()) {
                arpRequests.put(address, new ArpRequest(request));
            }
        }
    }

    @Override
    public String getName() {
        return "proxyarpmanager";
    }

    @Override
    public boolean isCallbackOrderingPrereq(OFType type, String name) {
        if (type == OFType.PACKET_IN) {
            return "devicemanager".equals(name)
                    || "onosdevicemanager".equals(name);
        } else {
            return false;
        }
    }

    @Override
    public boolean isCallbackOrderingPostreq(OFType type, String name) {
        return type == OFType.PACKET_IN && "onosforwarding".equals(name);
    }

    @Override
    public Command receive(IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {

        OFPacketIn pi = (OFPacketIn) msg;

        Ethernet eth = IFloodlightProviderService.bcStore.get(cntx,
                IFloodlightProviderService.CONTEXT_PI_PAYLOAD);

        if (eth.getEtherType() == Ethernet.TYPE_ARP) {
            ARP arp = (ARP) eth.getPayload();
            if (arp.getOpCode() == ARP.OP_REQUEST) {
                handleArpRequest(sw, pi, arp, eth);
            } else if (arp.getOpCode() == ARP.OP_REPLY) {
                // For replies we simply send a notification via Hazelcast
                sendArpReplyNotification(eth, pi);

                // handleArpReply(sw, pi, arp);
            }

            // Stop ARP packets here
            return Command.STOP;
        }

        // Propagate everything else
        return Command.CONTINUE;
    }

    private void handleArpRequest(IOFSwitch sw, OFPacketIn pi, ARP arp,
            Ethernet eth) {
        if (log.isTraceEnabled()) {
            log.trace("ARP request received for {}",
                    inetAddressToString(arp.getTargetProtocolAddress()));
        }

        InetAddress target;
        try {
            target = InetAddress.getByAddress(arp.getTargetProtocolAddress());
        } catch (UnknownHostException e) {
            log.debug("Invalid address in ARP request", e);
            return;
        }

        if (configService.fromExternalNetwork(sw.getId(), pi.getInPort())) {
            // If the request came from outside our network, we only care if
            // it was a request for one of our interfaces.
            if (configService.isInterfaceAddress(target)) {
                log.trace(
                        "ARP request for our interface. Sending reply {} => {}",
                        target.getHostAddress(),
                        configService.getRouterMacAddress());

                sendArpReply(arp, sw.getId(), pi.getInPort(),
                        configService.getRouterMacAddress());
            }

            return;
        }

        // MACAddress macAddress = arpCache.lookup(target);

        arpRequests.put(
                target,
                new ArpRequest(new HostArpRequester(arp, sw.getId(), pi
                        .getInPort()), false));

        // TODO: Fix the code below after deviceStorage was removed
        /*
        IDeviceObject targetDevice =
        		deviceStorage.getDeviceByIP(InetAddresses.coerceToInteger(target));
        */

        // TODO: Fix the code below after deviceStorage was removed
        /*
        if (targetDevice == null) {
        	if (log.isTraceEnabled()) {
        		log.trace("No device info found for {} - broadcasting",
        				target.getHostAddress());
        	}

        	// We don't know the device so broadcast the request out
        	datagrid.sendPacketOutNotification(
        			new BroadcastPacketOutNotification(eth.serialize(),
        					target, sw.getId(), pi.getInPort()));
        }
        else {
        	// Even if the device exists in our database, we do not reply to
        	// the request directly, but check whether the device is still valid
        	MACAddress macAddress = MACAddress.valueOf(targetDevice.getMACAddress());

        	if (log.isTraceEnabled()) {
        		log.trace("The target Device Record in DB is: {} => {} from ARP request host at {}/{}",
        				new Object [] {
        				inetAddressToString(arp.getTargetProtocolAddress()),
        				macAddress,
        				HexString.toHexString(sw.getId()), pi.getInPort()});
        	}

        	// sendArpReply(arp, sw.getId(), pi.getInPort(), macAddress);

        	Iterable<IPortObject> outPorts = targetDevice.getAttachedPorts();

        	if (!outPorts.iterator().hasNext()){
        		if (log.isTraceEnabled()) {
        			log.trace("Device {} exists but is not connected to any ports" +
        					" - broadcasting", macAddress);
        		}

        		datagrid.sendPacketOutNotification(
        				new BroadcastPacketOutNotification(eth.serialize(),
        						target, sw.getId(), pi.getInPort()));
        	}
        	else {
        		for (IPortObject portObject : outPorts) {
        			//long outSwitch = 0;
        			//short outPort = 0;

        			// if (!portObject.getLinkedPorts().iterator().hasNext()) {
        			//	outPort = portObject.getNumber();
        			// }
        			if (portObject.getLinkedPorts().iterator().hasNext()) {
        				continue;
        			}

        			short outPort = portObject.getNumber();
        			ISwitchObject outSwitchObject = portObject.getSwitch();
        			long outSwitch = HexString.toLong(outSwitchObject.getDPID());

        			if (log.isTraceEnabled()) {
        				log.trace("Probing device {} on port {}/{}",
        						new Object[] {macAddress,
        						HexString.toHexString(outSwitch), outPort});
        			}

        			datagrid.sendPacketOutNotification(
        					new SinglePacketOutNotification(eth.serialize(),
        							target, outSwitch, outPort));
        		}
        	}
        }
        */
    }

    // Not used because device manager currently updates the database
    // for ARP replies. May be useful in the future.
    private void handleArpReply(IOFSwitch sw, OFPacketIn pi, ARP arp) {
        if (log.isTraceEnabled()) {
            log.trace("ARP reply recieved: {} => {}, on {}/{}", new Object[] {
                    inetAddressToString(arp.getSenderProtocolAddress()),
                    HexString.toHexString(arp.getSenderHardwareAddress()),
                    HexString.toHexString(sw.getId()), pi.getInPort()});
        }

        InetAddress senderIpAddress;
        try {
            senderIpAddress = InetAddress.getByAddress(arp
                    .getSenderProtocolAddress());
        } catch (UnknownHostException e) {
            log.debug("Invalid address in ARP reply", e);
            return;
        }

        MACAddress senderMacAddress = MACAddress.valueOf(arp
                .getSenderHardwareAddress());

        // See if anyone's waiting for this ARP reply
        Set<ArpRequest> requests = arpRequests.get(senderIpAddress);

        // Synchronize on the Multimap while using an iterator for one of the
        // sets
        List<ArpRequest> requestsToSend = new ArrayList<ArpRequest>(
                requests.size());
        synchronized (arpRequests) {
            Iterator<ArpRequest> it = requests.iterator();
            while (it.hasNext()) {
                ArpRequest request = it.next();
                it.remove();
                requestsToSend.add(request);
            }
        }

        // Don't hold an ARP lock while dispatching requests
        for (ArpRequest request : requestsToSend) {
            request.dispatchReply(senderIpAddress, senderMacAddress);
        }
    }

    private void sendArpRequestForAddress(InetAddress ipAddress) {
        // TODO what should the sender IP address and MAC address be if no
        // IP addresses are configured? Will there ever be a need to send
        // ARP requests from the controller in that case?
        // All-zero MAC address doesn't seem to work - hosts don't respond to it

        byte[] zeroIpv4 = {0x0, 0x0, 0x0, 0x0};
        byte[] zeroMac = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0};
        byte[] genericNonZeroMac = {0x0, 0x0, 0x0, 0x0, 0x0, 0x01};
        byte[] broadcastMac = {(byte) 0xff, (byte) 0xff, (byte) 0xff,
                (byte) 0xff, (byte) 0xff, (byte) 0xff};

        ARP arpRequest = new ARP();

        arpRequest
                .setHardwareType(ARP.HW_TYPE_ETHERNET)
                .setProtocolType(ARP.PROTO_TYPE_IP)
                .setHardwareAddressLength(
                        (byte) Ethernet.DATALAYER_ADDRESS_LENGTH)
                .setProtocolAddressLength((byte) IPv4.ADDRESS_LENGTH)
                .setOpCode(ARP.OP_REQUEST).setTargetHardwareAddress(zeroMac)
                .setTargetProtocolAddress(ipAddress.getAddress());

        MACAddress routerMacAddress = configService.getRouterMacAddress();
        // TODO hack for now as it's unclear what the MAC address should be
        byte[] senderMacAddress = genericNonZeroMac;
        if (routerMacAddress != null) {
            senderMacAddress = routerMacAddress.toBytes();
        }
        arpRequest.setSenderHardwareAddress(senderMacAddress);

        byte[] senderIPAddress = zeroIpv4;
        Interface intf = configService.getOutgoingInterface(ipAddress);
        if (intf != null) {
            senderIPAddress = intf.getIpAddress().getAddress();
        }

        arpRequest.setSenderProtocolAddress(senderIPAddress);

        Ethernet eth = new Ethernet();
        eth.setSourceMACAddress(senderMacAddress)
                .setDestinationMACAddress(broadcastMac)
                .setEtherType(Ethernet.TYPE_ARP).setPayload(arpRequest);

        if (vlan != NO_VLAN) {
            eth.setVlanID(vlan).setPriorityCode((byte) 0);
        }

        // sendArpRequestToSwitches(ipAddress, eth.serialize());
        datagrid.sendPacketOutNotification(new SinglePacketOutNotification(eth
                .serialize(), ipAddress, intf.getDpid(), intf.getPort()));
    }

    private void sendArpRequestToSwitches(InetAddress dstAddress,
            byte[] arpRequest) {
        sendArpRequestToSwitches(dstAddress, arpRequest, 0,
                OFPort.OFPP_NONE.getValue());
    }

    private void sendArpRequestToSwitches(InetAddress dstAddress,
            byte[] arpRequest, long inSwitch, short inPort) {

        if (configService.hasLayer3Configuration()) {
            Interface intf = configService.getOutgoingInterface(dstAddress);
            if (intf == null) {
                // TODO here it should be broadcast out all non-interface edge
                // ports.
                // I think we can assume that if it's not a request for an
                // external
                // network, it's an ARP for a host in our own network. So we
                // want to
                // send it out all edge ports that don't have an interface
                // configured
                // to ensure it reaches all hosts in our network.
                log.debug("No interface found to send ARP request for {}",
                        dstAddress.getHostAddress());
            } else {
                sendArpRequestOutPort(arpRequest, intf.getDpid(),
                        intf.getPort());
            }
        } else {
            // broadcastArpRequestOutEdge(arpRequest, inSwitch, inPort);
            broadcastArpRequestOutMyEdge(arpRequest, inSwitch, inPort);
        }
    }

    private void sendArpReplyNotification(Ethernet eth, OFPacketIn pi) {
        ARP arp = (ARP) eth.getPayload();

        if (log.isTraceEnabled()) {
            log.trace("Sending ARP reply for {} to other ONOS instances",
                    inetAddressToString(arp.getSenderProtocolAddress()));
        }

        InetAddress targetAddress;

        try {
            targetAddress = InetAddress.getByAddress(arp
                    .getSenderProtocolAddress());
        } catch (UnknownHostException e) {
            log.error("Unknown host", e);
            return;
        }

        MACAddress mac = new MACAddress(arp.getSenderHardwareAddress());

        datagrid.sendArpReplyNotification(new ArpReplyNotification(
                targetAddress, mac));
    }

    private void broadcastArpRequestOutMyEdge(byte[] arpRequest, long inSwitch,
            short inPort) {
        List<SwitchPort> switchPorts = new ArrayList<SwitchPort>();

        for (IOFSwitch sw : floodlightProvider.getSwitches().values()) {

            OFPacketOut po = new OFPacketOut();
            po.setInPort(OFPort.OFPP_NONE).setBufferId(-1)
                    .setPacketData(arpRequest);

            List<OFAction> actions = new ArrayList<OFAction>();

            // TODO: Fix the code below after topoSwitchService was removed
            /*
            Iterable<IPortObject> ports
            	= topoSwitchService.getPortsOnSwitch(sw.getStringId());
            if (ports == null) {
            	continue;
            }

            for (IPortObject portObject : ports) {
            	if (!portObject.getLinkedPorts().iterator().hasNext()) {
            		short portNumber = portObject.getNumber();

            		if (sw.getId() == inSwitch && portNumber == inPort) {
            			// This is the port that the ARP message came in,
            			// so don't broadcast out this port
            			continue;
            		}

            		switchPorts.add(new SwitchPort(new Dpid(sw.getId()),
            				new Port(portNumber)));
            		actions.add(new OFActionOutput(portNumber));
            	}
            }
            */

            po.setActions(actions);
            short actionsLength = (short) (actions.size() * OFActionOutput.MINIMUM_LENGTH);
            po.setActionsLength(actionsLength);
            po.setLengthU(OFPacketOut.MINIMUM_LENGTH + actionsLength
                    + arpRequest.length);

            flowPusher.add(sw, po);
        }

        if (log.isTraceEnabled()) {
            log.trace("Broadcast ARP request to: {}", switchPorts);
        }
    }

    private void sendArpRequestOutPort(byte[] arpRequest, long dpid, short port) {
        if (log.isTraceEnabled()) {
            log.trace("Sending ARP request out {}/{}",
                    HexString.toHexString(dpid), port);
        }

        OFPacketOut po = new OFPacketOut();
        po.setInPort(OFPort.OFPP_NONE).setBufferId(-1)
                .setPacketData(arpRequest);

        List<OFAction> actions = new ArrayList<OFAction>();
        actions.add(new OFActionOutput(port));
        po.setActions(actions);
        short actionsLength = (short) (actions.size() * OFActionOutput.MINIMUM_LENGTH);
        po.setActionsLength(actionsLength);
        po.setLengthU(OFPacketOut.MINIMUM_LENGTH + actionsLength
                + arpRequest.length);

        IOFSwitch sw = floodlightProvider.getSwitches().get(dpid);

        if (sw == null) {
            log.warn("Switch not found when sending ARP request");
            return;
        }

        flowPusher.add(sw, po);
    }

    private void sendArpReply(ARP arpRequest, long dpid, short port,
            MACAddress targetMac) {
        if (log.isTraceEnabled()) {
            log.trace(
                    "Sending reply {} => {} to {}",
                    new Object[] {
                            inetAddressToString(arpRequest
                                    .getTargetProtocolAddress()),
                            targetMac,
                            inetAddressToString(arpRequest
                                    .getSenderProtocolAddress())});
        }

        ARP arpReply = new ARP();
        arpReply.setHardwareType(ARP.HW_TYPE_ETHERNET)
                .setProtocolType(ARP.PROTO_TYPE_IP)
                .setHardwareAddressLength(
                        (byte) Ethernet.DATALAYER_ADDRESS_LENGTH)
                .setProtocolAddressLength((byte) IPv4.ADDRESS_LENGTH)
                .setOpCode(ARP.OP_REPLY)
                .setSenderHardwareAddress(targetMac.toBytes())
                .setSenderProtocolAddress(arpRequest.getTargetProtocolAddress())
                .setTargetHardwareAddress(arpRequest.getSenderHardwareAddress())
                .setTargetProtocolAddress(arpRequest.getSenderProtocolAddress());

        Ethernet eth = new Ethernet();
        eth.setDestinationMACAddress(arpRequest.getSenderHardwareAddress())
                .setSourceMACAddress(targetMac.toBytes())
                .setEtherType(Ethernet.TYPE_ARP).setPayload(arpReply);

        if (vlan != NO_VLAN) {
            eth.setVlanID(vlan).setPriorityCode((byte) 0);
        }

        List<OFAction> actions = new ArrayList<OFAction>();
        actions.add(new OFActionOutput(port));

        OFPacketOut po = new OFPacketOut();
        po.setInPort(OFPort.OFPP_NONE)
                .setBufferId(-1)
                .setPacketData(eth.serialize())
                .setActions(actions)
                .setActionsLength((short) OFActionOutput.MINIMUM_LENGTH)
                .setLengthU(
                        OFPacketOut.MINIMUM_LENGTH
                                + OFActionOutput.MINIMUM_LENGTH
                                + po.getPacketData().length);

        List<OFMessage> msgList = new ArrayList<OFMessage>();
        msgList.add(po);

        IOFSwitch sw = floodlightProvider.getSwitches().get(dpid);

        if (sw == null) {
            log.warn("Switch {} not found when sending ARP reply",
                    HexString.toHexString(dpid));
            return;
        }

        flowPusher.add(sw, po);
    }

    private String inetAddressToString(byte[] bytes) {
        try {
            return InetAddress.getByAddress(bytes).getHostAddress();
        } catch (UnknownHostException e) {
            log.debug("Invalid IP address", e);
            return "";
        }
    }

    /*
     * IProxyArpService methods
     */

    @Override
    public MACAddress getMacAddress(InetAddress ipAddress) {
        // return arpCache.lookup(ipAddress);
        return null;
    }

    @Override
    public void sendArpRequest(InetAddress ipAddress, IArpRequester requester,
            boolean retry) {
        arpRequests.put(ipAddress, new ArpRequest(requester, retry));

        // Sanity check to make sure we don't send a request for our own address
        if (!configService.isInterfaceAddress(ipAddress)) {
            sendArpRequestForAddress(ipAddress);
        }
    }

    @Override
    public List<String> getMappings() {
        return new ArrayList<String>();
    }

    /*
    @Override
    public void arpRequestNotification(ArpMessage arpMessage) {
    	log.debug("Received ARP notification from other instances");

    	switch (arpMessage.getType()){
    	case REQUEST:
    		if(arpMessage.getOutSwitch() == -1 || arpMessage.getOutPort() == -1){
    			broadcastArpRequestOutMyEdge(arpMessage.getPacket(),
    					arpMessage.getInSwitch(), arpMessage.getInPort());
    		}else{
    			sendArpRequestOutPort(arpMessage.getPacket(),arpMessage.getOutSwitch(),arpMessage.getOutPort());
    			log.debug("OutSwitch in ARP request message is: {}; " +
    			"OutPort in ARP request message is: {}",arpMessage.getOutSwitch(),arpMessage.getOutPort());
    		}
    		break;
    	case REPLY:
    		log.debug("Received ARP reply notification for {}",
    				arpMessage.getAddress());
    		sendArpReplyToWaitingRequesters(arpMessage.getAddress(),arpMessage.getMAC());
    		break;
    	}
    }
    */

    private void sendArpReplyToWaitingRequesters(InetAddress address,
            MACAddress mac) {
        log.debug("Sending ARP reply for {} to requesters",
                address.getHostAddress());

        // See if anyone's waiting for this ARP reply
        Set<ArpRequest> requests = arpRequests.get(address);

        // Synchronize on the Multimap while using an iterator for one of the
        // sets
        List<ArpRequest> requestsToSend = new ArrayList<ArpRequest>(
                requests.size());
        synchronized (arpRequests) {
            Iterator<ArpRequest> it = requests.iterator();
            while (it.hasNext()) {
                ArpRequest request = it.next();
                it.remove();
                requestsToSend.add(request);
            }
        }

        /*IDeviceObject deviceObject = deviceStorage.getDeviceByIP(
        		InetAddresses.coerceToInteger(address));

        MACAddress mac = MACAddress.valueOf(deviceObject.getMACAddress());

        log.debug("Found {} at {} in network map",
        		address.getHostAddress(), mac);*/

        // Don't hold an ARP lock while dispatching requests
        for (ArpRequest request : requestsToSend) {
            request.dispatchReply(address, mac);
        }
    }

    @Override
    public void arpReplyEvent(ArpReplyNotification arpReply) {
        log.debug("Received ARP reply notification for {}",
                arpReply.getTargetAddress());
        sendArpReplyToWaitingRequesters(arpReply.getTargetAddress(),
                arpReply.getTargetMacAddress());
    }

    @Override
    public void packetOutNotification(
            PacketOutNotification packetOutNotification) {

        if (packetOutNotification instanceof SinglePacketOutNotification) {
            SinglePacketOutNotification notification = (SinglePacketOutNotification) packetOutNotification;
            sendArpRequestOutPort(notification.packet,
                    notification.getOutSwitch(), notification.getOutPort());

            // set timestamp
            InetAddress addr = notification.getTargetAddress();
            if (addr != null) {
                for (ArpRequest request : arpRequests.get(addr)) {
                    request.setRequestTime();
                }
            }
        } else if (packetOutNotification instanceof BroadcastPacketOutNotification) {
            BroadcastPacketOutNotification notification = (BroadcastPacketOutNotification) packetOutNotification;
            broadcastArpRequestOutMyEdge(notification.packet,
                    notification.getInSwitch(), notification.getInPort());

            // set timestamp
            InetAddress addr = notification.getTargetAddress();
            if (addr != null) {
                for (ArpRequest request : arpRequests.get(addr)) {
                    request.setRequestTime();
                }
            }
        } else {
            log.warn("Unknown packet out notification received");
        }
    }
}