Unit tests for packet processing the the AAA app

Change-Id: I51149fdf9ce5bfe4ee8d67564165b94f3e39e379

@@ -44,31 +44,36 @@
 
 
         <dependency>
         <dependency>
             <groupId>org.onosproject</groupId>
             <groupId>org.onosproject</groupId>
-            <artifactId>onlab-junit</artifactId>
-            <scope>test</scope>
+            <artifactId>onos-api</artifactId>
+            <version>${project.version}</version>
         </dependency>
         </dependency>
 
 
         <dependency>
         <dependency>
             <groupId>org.onosproject</groupId>
             <groupId>org.onosproject</groupId>
-            <artifactId>onos-api</artifactId>
+            <artifactId>onos-app-xos-integration</artifactId>
             <version>${project.version}</version>
             <version>${project.version}</version>
         </dependency>
         </dependency>
 
 
         <dependency>
         <dependency>
             <groupId>org.onosproject</groupId>
             <groupId>org.onosproject</groupId>
-            <artifactId>onlab-osgi</artifactId>
-            <version>${project.version}</version>
+            <artifactId>onlab-junit</artifactId>
+            <scope>test</scope>
         </dependency>
         </dependency>
 
 
         <dependency>
         <dependency>
-            <groupId>org.apache.felix</groupId>
-            <artifactId>org.apache.felix.scr.annotations</artifactId>
+            <groupId>org.onosproject</groupId>
+            <artifactId>onlab-osgi</artifactId>
+            <version>${project.version}</version>
+            <classifier>tests</classifier>
+            <scope>test</scope>
         </dependency>
         </dependency>
 
 
         <dependency>
         <dependency>
             <groupId>org.onosproject</groupId>
             <groupId>org.onosproject</groupId>
-            <artifactId>onos-app-xos-integration</artifactId>
+            <artifactId>onos-api</artifactId>
             <version>${project.version}</version>
             <version>${project.version}</version>
+            <classifier>tests</classifier>
+            <scope>test</scope>
         </dependency>
         </dependency>
     </dependencies>
     </dependencies>
 
 

@@ -136,23 +136,23 @@ public class AAA {
 
 
     @Property(name = "radiusIpAddress", value = DEFAULT_RADIUS_IP,
     @Property(name = "radiusIpAddress", value = DEFAULT_RADIUS_IP,
             label = "RADIUS IP Address")
             label = "RADIUS IP Address")
-    private String radiusIpAddress = DEFAULT_RADIUS_IP;
+    protected String radiusIpAddress = DEFAULT_RADIUS_IP;
 
 
     @Property(name = "nasIpAddress", value = DEFAULT_NAS_IP,
     @Property(name = "nasIpAddress", value = DEFAULT_NAS_IP,
             label = "NAS IP Address")
             label = "NAS IP Address")
-    private String nasIpAddress = DEFAULT_NAS_IP;
+    protected String nasIpAddress = DEFAULT_NAS_IP;
 
 
     @Property(name = "radiusMacAddress", value = RADIUS_MAC_ADDRESS,
     @Property(name = "radiusMacAddress", value = RADIUS_MAC_ADDRESS,
             label = "RADIUS MAC Address")
             label = "RADIUS MAC Address")
-    private String radiusMacAddress = RADIUS_MAC_ADDRESS;
+    protected String radiusMacAddress = RADIUS_MAC_ADDRESS;
 
 
     @Property(name = "nasMacAddress", value = NAS_MAC_ADDRESS,
     @Property(name = "nasMacAddress", value = NAS_MAC_ADDRESS,
             label = "NAS MAC Address")
             label = "NAS MAC Address")
-    private String nasMacAddress = NAS_MAC_ADDRESS;
+    protected String nasMacAddress = NAS_MAC_ADDRESS;
 
 
     @Property(name = "radiusSecret", value = DEFAULT_RADIUS_SECRET,
     @Property(name = "radiusSecret", value = DEFAULT_RADIUS_SECRET,
             label = "RADIUS shared secret")
             label = "RADIUS shared secret")
-    private String radiusSecret = DEFAULT_RADIUS_SECRET;
+    protected String radiusSecret = DEFAULT_RADIUS_SECRET;
 
 
     @Property(name = "radiusSwitchId", value = DEFAULT_RADIUS_SWITCH,
     @Property(name = "radiusSwitchId", value = DEFAULT_RADIUS_SWITCH,
             label = "Radius switch")
             label = "Radius switch")

@@ -15,29 +15,471 @@
  */
  */
 package org.onosproject.aaa;
 package org.onosproject.aaa;
 
 
+import java.nio.ByteBuffer;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+
 import org.junit.After;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.Test;
+import org.onlab.osgi.ComponentContextAdapter;
+import org.onlab.packet.Data;
+import org.onlab.packet.DeserializationException;
+import org.onlab.packet.EAP;
+import org.onlab.packet.EAPOL;
+import org.onlab.packet.EthType;
+import org.onlab.packet.Ethernet;
+import org.onlab.packet.IPv4;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.MacAddress;
+import org.onlab.packet.RADIUS;
+import org.onlab.packet.RADIUSAttribute;
+import org.onlab.packet.UDP;
+import org.onlab.packet.VlanId;
+import org.onosproject.cfg.ComponentConfigAdapter;
+import org.onosproject.core.CoreServiceAdapter;
+import org.onosproject.net.Annotations;
+import org.onosproject.net.Host;
+import org.onosproject.net.HostId;
+import org.onosproject.net.HostLocation;
+import org.onosproject.net.host.HostServiceAdapter;
+import org.onosproject.net.packet.DefaultInboundPacket;
+import org.onosproject.net.packet.DefaultPacketContext;
+import org.onosproject.net.packet.InboundPacket;
+import org.onosproject.net.packet.OutboundPacket;
+import org.onosproject.net.packet.PacketContext;
+import org.onosproject.net.packet.PacketProcessor;
+import org.onosproject.net.packet.PacketServiceAdapter;
+import org.onosproject.net.provider.ProviderId;
+
+import com.google.common.base.Charsets;
+import com.google.common.collect.ImmutableSet;
+
+import static org.hamcrest.Matchers.instanceOf;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.fail;
+import static org.onosproject.net.NetTestTools.connectPoint;
 
 
 /**
 /**
  * Set of tests of the ONOS application component.
  * Set of tests of the ONOS application component.
  */
  */
 public class AAATest {
 public class AAATest {
 
 
+    MacAddress clientMac = MacAddress.valueOf("1a:1a:1a:1a:1a:1a");
+    MacAddress serverMac = MacAddress.valueOf("2a:2a:2a:2a:2a:2a");
+
+    PacketProcessor packetProcessor;
     private AAA aaa;
     private AAA aaa;
+    List<Ethernet> savedPackets = new LinkedList<>();
+
+    /**
+     * Saves the given packet onto the saved packets list.
+     *
+     * @param eth packet to save
+     */
+    private void savePacket(Ethernet eth) {
+        savedPackets.add(eth);
+    }
+
+    /**
+     * Keeps a reference to the PacketProcessor and saves the OutboundPackets.
+     */
+    private class MockPacketService extends PacketServiceAdapter {
+
+        @Override
+        public void addProcessor(PacketProcessor processor, int priority) {
+            packetProcessor = processor;
+        }
+
+        @Override
+        public void emit(OutboundPacket packet) {
+            try {
+                Ethernet eth = Ethernet.deserializer().deserialize(packet.data().array(),
+                                                                   0, packet.data().array().length);
+                savePacket(eth);
+            } catch (Exception e) {
+                fail(e.getMessage());
+            }
+        }
+    }
+
+    /**
+     * Mocks the DefaultPacketContext.
+     */
+    private final class TestPacketContext extends DefaultPacketContext {
+
+        private TestPacketContext(long time, InboundPacket inPkt,
+                                  OutboundPacket outPkt, boolean block) {
+            super(time, inPkt, outPkt, block);
+        }
+
+        @Override
+        public void send() {
+            // We don't send anything out.
+        }
+    }
+
+    /**
+     * Mocks a host to allow locating the Radius server.
+     */
+    private static final class MockHost implements Host {
+        @Override
+        public HostId id() {
+            return null;
+        }
+
+        @Override
+        public MacAddress mac() {
+            return null;
+        }
+
+        @Override
+        public VlanId vlan() {
+            return VlanId.vlanId(VlanId.UNTAGGED);
+        }
+
+        @Override
+        public Set<IpAddress> ipAddresses() {
+            return null;
+        }
+
+        @Override
+        public HostLocation location() {
+            return null;
+        }
+
+        @Override
+        public Annotations annotations() {
+            return null;
+        }
+
+        @Override
+        public ProviderId providerId() {
+            return null;
+        }
+    }
+
+    /**
+     * Mocks the Host service.
+     */
+    private static final class MockHostService extends HostServiceAdapter {
+        @Override
+        public Set<Host> getHostsByIp(IpAddress ip) {
+            return ImmutableSet.of(new MockHost());
+        }
+    }
+
+    /**
+     * Sends an Ethernet packet to the process method of the Packet Processor.
+     *
+     * @param reply Ethernet packet
+     */
+    private void sendPacket(Ethernet reply) {
+        final ByteBuffer byteBuffer = ByteBuffer.wrap(reply.serialize());
+        InboundPacket inPacket = new DefaultInboundPacket(connectPoint("1", 1),
+                                                          reply,
+                                                          byteBuffer);
+
+        PacketContext context = new TestPacketContext(127L, inPacket, null, false);
+        packetProcessor.process(context);
+    }
+
+    /**
+     * Constructs an Ethernet packet containing a EAPOL_START Payload.
+     *
+     * @return Ethernet packet
+     */
+    private Ethernet constructSupplicantStartPacket() {
+        Ethernet eth = new Ethernet();
+        eth.setDestinationMACAddress(clientMac.toBytes());
+        eth.setSourceMACAddress(serverMac.toBytes());
+        eth.setEtherType(EthType.EtherType.EAPOL.ethType().toShort());
+        eth.setVlanID((short) 2);
+
+        EAP eap = new EAP(EAPOL.EAPOL_START, (byte) 1, EAPOL.EAPOL_START, null);
+
+        //eapol header
+        EAPOL eapol = new EAPOL();
+        eapol.setEapolType(EAPOL.EAPOL_START);
+        eapol.setPacketLength(eap.getLength());
+
+        //eap part
+        eapol.setPayload(eap);
+
+        eth.setPayload(eapol);
+        eth.setPad(true);
+        return eth;
+    }
+
+    /**
+     * Constructs an Ethernet packet containing identification payload.
+     *
+     * @return Ethernet packet
+     */
+    private Ethernet constructSupplicantIdentifyPacket(byte type) {
+        Ethernet eth = new Ethernet();
+        eth.setDestinationMACAddress(clientMac.toBytes());
+        eth.setSourceMACAddress(serverMac.toBytes());
+        eth.setEtherType(EthType.EtherType.EAPOL.ethType().toShort());
+        eth.setVlanID((short) 2);
+
+        String username = "user";
+        EAP eap = new EAP(EAP.REQUEST, (byte) 1, type,
+                          username.getBytes(Charsets.US_ASCII));
+        eap.setIdentifier((byte) 1);
+
+        // eapol header
+        EAPOL eapol = new EAPOL();
+        eapol.setEapolType(EAPOL.EAPOL_PACKET);
+        eapol.setPacketLength(eap.getLength());
+
+        // eap part
+        eapol.setPayload(eap);
+
+        eth.setPayload(eapol);
+        eth.setPad(true);
+        return eth;
+    }
 
 
+    /**
+     * Constructs an Ethernet packet containing a RADIUS challenge
+     * packet.
+     *
+     * @param challengeCode code to use in challenge packet
+     * @param challengeType type to use in challenge packet
+     * @return Ethernet packet
+     */
+    private Ethernet constructRADIUSCodeAccessChallengePacket(byte challengeCode, byte challengeType) {
+        Ethernet eth = new Ethernet();
+        eth.setDestinationMACAddress(clientMac.toBytes());
+        eth.setSourceMACAddress(serverMac.toBytes());
+        eth.setEtherType(EthType.EtherType.IPV4.ethType().toShort());
+        eth.setVlanID((short) 2);
+
+        IPv4 ipv4 = new IPv4();
+        ipv4.setProtocol(IPv4.PROTOCOL_UDP);
+        ipv4.setSourceAddress("127.0.0.1");
+
+        String challenge = "1234";
+
+        EAP eap = new EAP(challengeType, (byte) 1, challengeType,
+                          challenge.getBytes(Charsets.US_ASCII));
+        eap.setIdentifier((byte) 1);
+
+        RADIUS radius = new RADIUS();
+        radius.setCode(challengeCode);
+
+        radius.setAttribute(RADIUSAttribute.RADIUS_ATTR_STATE,
+                            challenge.getBytes(Charsets.US_ASCII));
+
+        radius.setPayload(eap);
+        radius.setAttribute(RADIUSAttribute.RADIUS_ATTR_EAP_MESSAGE,
+                            eap.serialize());
+
+        UDP udp = new UDP();
+        udp.setPayload(radius);
+        ipv4.setPayload(udp);
+
+        eth.setPayload(ipv4);
+        eth.setPad(true);
+        return eth;
+    }
+
+    /**
+     * Sets up the services required by the AAA application.
+     */
     @Before
     @Before
     public void setUp() {
     public void setUp() {
-
+        aaa = new AAA();
+        aaa.cfgService = new ComponentConfigAdapter();
+        aaa.coreService = new CoreServiceAdapter();
+        aaa.packetService = new MockPacketService();
+        aaa.hostService = new MockHostService();
+        aaa.activate(new ComponentContextAdapter());
     }
     }
 
 
+    /**
+     * Tears down the AAA application.
+     */
     @After
     @After
     public void tearDown() {
     public void tearDown() {
+        aaa.deactivate();
     }
     }
 
 
-    @Test
-    public void basics() {
+    /**
+     * Extracts the RADIUS packet from a packet sent by the supplicant.
+     *
+     * @param supplicantPacket packet sent by the supplicant
+     * @return RADIUS packet
+     * @throws DeserializationException if deserialization of the packet contents
+     *         fails.
+     */
+    private RADIUS checkAndFetchRADIUSPacketFromSupplicant(Ethernet supplicantPacket)
+            throws DeserializationException {
+        assertThat(supplicantPacket, notNullValue());
+        assertThat(supplicantPacket.getVlanID(), is(VlanId.UNTAGGED));
+        assertThat(supplicantPacket.getSourceMAC().toString(), is(aaa.nasMacAddress));
+        assertThat(supplicantPacket.getDestinationMAC().toString(), is(aaa.radiusMacAddress));
+
+        assertThat(supplicantPacket.getPayload(), instanceOf(IPv4.class));
+        IPv4 ipv4 = (IPv4) supplicantPacket.getPayload();
+        assertThat(ipv4, notNullValue());
+        assertThat(IpAddress.valueOf(ipv4.getSourceAddress()).toString(),
+                   is(aaa.nasIpAddress));
+        assertThat(IpAddress.valueOf(ipv4.getDestinationAddress()).toString(),
+                   is(aaa.radiusIpAddress));
+
+        assertThat(ipv4.getPayload(), instanceOf(UDP.class));
+        UDP udp = (UDP) ipv4.getPayload();
+        assertThat(udp, notNullValue());
+
+        assertThat(udp.getPayload(), instanceOf(Data.class));
+        Data data = (Data) udp.getPayload();
+        RADIUS radius = RADIUS.deserializer()
+                .deserialize(data.getData(), 0, data.getData().length);
+        assertThat(radius, notNullValue());
+        return radius;
+    }
+
+    /**
+     * Checks the contents of a RADIUS packet being sent to the RADIUS server.
+     *
+     * @param radiusPacket packet to check
+     * @param code expected code
+     */
+    private void checkRadiusPacket(Ethernet radiusPacket, byte code) {
+        assertThat(radiusPacket.getVlanID(), is((short) 2));
+
+        // TODO: These address values seem wrong, but are produced by the current AAA implementation
+        assertThat(radiusPacket.getSourceMAC(), is(MacAddress.valueOf(1L)));
+        assertThat(radiusPacket.getDestinationMAC(), is(serverMac));
+
+        assertThat(radiusPacket.getPayload(), instanceOf(EAPOL.class));
+        EAPOL eapol = (EAPOL) radiusPacket.getPayload();
+        assertThat(eapol, notNullValue());
+
+        assertThat(eapol.getEapolType(), is(EAPOL.EAPOL_PACKET));
+        assertThat(eapol.getPayload(), instanceOf(EAP.class));
+        EAP eap = (EAP) eapol.getPayload();
+        assertThat(eap, notNullValue());
+        assertThat(eap.getCode(), is(code));
+    }
 
 
+    /**
+     * Fetches the sent packet at the given index. The requested packet
+     * must be the last packet on the list.
+     *
+     * @param index index into sent packets array
+     * @return packet
+     */
+    private Ethernet fetchPacket(int index) {
+        assertThat(savedPackets.size(), is(index + 1));
+        Ethernet eth = savedPackets.get(index);
+        assertThat(eth, notNullValue());
+        return eth;
     }
     }
 
 
+    /**
+     * Tests the authentication path through the AAA application.
+     *
+     * @throws DeserializationException if packed deserialization fails.
+     */
+    @Test
+    public void testAuthentication()  throws DeserializationException {
+
+        // Our session id will be the device ID ("of:1") with the port ("1") concatenated
+        String sessionId = "of:11";
+
+        //  (1) Supplicant start up
+
+        Ethernet startPacket = constructSupplicantStartPacket();
+        sendPacket(startPacket);
+
+        Ethernet responsePacket = fetchPacket(0);
+        checkRadiusPacket(responsePacket, EAP.ATTR_IDENTITY);
+
+        //  (2) Supplicant identify
+
+        Ethernet identifyPacket = constructSupplicantIdentifyPacket(EAP.ATTR_IDENTITY);
+        sendPacket(identifyPacket);
+
+        Ethernet radiusIdentifyPacket = fetchPacket(1);
+
+        RADIUS radiusAccessRequest = checkAndFetchRADIUSPacketFromSupplicant(radiusIdentifyPacket);
+        assertThat(radiusAccessRequest, notNullValue());
+        assertThat(radiusAccessRequest.getCode(), is(RADIUS.RADIUS_CODE_ACCESS_REQUEST));
+        assertThat(new String(radiusAccessRequest.getAttribute(RADIUSAttribute.RADIUS_ATTR_USERNAME).getValue()),
+                   is("user"));
+
+        IpAddress nasIp =
+                IpAddress.valueOf(IpAddress.Version.INET,
+                                  radiusAccessRequest.getAttribute(RADIUSAttribute.RADIUS_ATTR_NAS_IP)
+                                          .getValue());
+        assertThat(nasIp.toString(), is("127.0.0.1"));
+
+        //  State machine should have been created by now
+
+        StateMachine stateMachine =
+                StateMachine.lookupStateMachineBySessionId(sessionId);
+        assertThat(stateMachine, notNullValue());
+        assertThat(stateMachine.state(), is(StateMachine.STATE_PENDING));
+
+        // (3) RADIUS MD5 challenge
+
+        Ethernet radiusCodeAccessChallengePacket =
+                constructRADIUSCodeAccessChallengePacket(RADIUS.RADIUS_CODE_ACCESS_CHALLENGE, EAP.ATTR_MD5);
+        sendPacket(radiusCodeAccessChallengePacket);
+
+        Ethernet radiusChallengeMD5Packet = fetchPacket(2);
+        checkRadiusPacket(radiusChallengeMD5Packet, EAP.ATTR_MD5);
+
+        // (4) Supplicant MD5 response
+
+        Ethernet md5RadiusPacket = constructSupplicantIdentifyPacket(EAP.ATTR_MD5);
+        sendPacket(md5RadiusPacket);
+        Ethernet supplicantMD5ResponsePacket = fetchPacket(3);
+        RADIUS responseMd5RadiusPacket = checkAndFetchRADIUSPacketFromSupplicant(supplicantMD5ResponsePacket);
+        assertThat(responseMd5RadiusPacket.getIdentifier(), is((byte) 1));
+        assertThat(responseMd5RadiusPacket.getCode(), is(RADIUS.RADIUS_CODE_ACCESS_REQUEST));
+
+        //  State machine should be in pending state
+
+        assertThat(stateMachine, notNullValue());
+        assertThat(stateMachine.state(), is(StateMachine.STATE_PENDING));
+
+        // (5) RADIUS TLS Challenge
+
+        Ethernet radiusCodeAccessChallengeTLSPacket =
+                constructRADIUSCodeAccessChallengePacket(RADIUS.RADIUS_CODE_ACCESS_CHALLENGE, EAP.ATTR_TLS);
+        sendPacket(radiusCodeAccessChallengeTLSPacket);
+
+        Ethernet radiusChallengeTLSPacket = fetchPacket(4);
+        checkRadiusPacket(radiusChallengeTLSPacket, EAP.ATTR_TLS);
+
+        // (6) Supplicant TLS response
+
+        Ethernet tlsRadiusPacket = constructSupplicantIdentifyPacket(EAP.ATTR_TLS);
+        sendPacket(tlsRadiusPacket);
+        Ethernet supplicantTLSResponsePacket = fetchPacket(5);
+        RADIUS responseTLSRadiusPacket = checkAndFetchRADIUSPacketFromSupplicant(supplicantTLSResponsePacket);
+        assertThat(responseTLSRadiusPacket.getIdentifier(), is((byte) 0));
+        assertThat(responseTLSRadiusPacket.getCode(), is(RADIUS.RADIUS_CODE_ACCESS_REQUEST));
+
+        // (7) RADIUS Success
+
+        Ethernet successPacket =
+                constructRADIUSCodeAccessChallengePacket(RADIUS.RADIUS_CODE_ACCESS_ACCEPT, EAP.SUCCESS);
+        sendPacket(successPacket);
+        Ethernet supplicantSuccessPacket = fetchPacket(6);
+
+        checkRadiusPacket(supplicantSuccessPacket, EAP.SUCCESS);
+
+        //  State machine should be in authorized state
+
+        assertThat(stateMachine, notNullValue());
+        assertThat(stateMachine.state(), is(StateMachine.STATE_AUTHORIZED));
+    }
 }
 }

@@ -17,10 +17,13 @@ package org.onosproject.cfg;
 
 
 import java.util.Set;
 import java.util.Set;
 
 
+import com.google.common.collect.ImmutableSet;
+
 /**
 /**
  * Adapter for testing against component configuration service.
  * Adapter for testing against component configuration service.
  */
  */
 public class ComponentConfigAdapter implements ComponentConfigService {
 public class ComponentConfigAdapter implements ComponentConfigService {
+
     @Override
     @Override
     public Set<String> getComponentNames() {
     public Set<String> getComponentNames() {
         return null;
         return null;
@@ -38,7 +41,7 @@ public class ComponentConfigAdapter implements ComponentConfigService {
 
 
     @Override
     @Override
     public Set<ConfigProperty> getProperties(String componentName) {
     public Set<ConfigProperty> getProperties(String componentName) {
-        return null;
+        return ImmutableSet.of();
     }
     }
 
 
     @Override
     @Override

@@ -22,17 +22,56 @@ import org.osgi.service.component.ComponentContext;
 import org.osgi.service.component.ComponentInstance;
 import org.osgi.service.component.ComponentInstance;
 
 
 import java.util.Dictionary;
 import java.util.Dictionary;
+import java.util.Enumeration;
 
 
 /**
 /**
  * Adapter implementation of OSGI component context.
  * Adapter implementation of OSGI component context.
  */
  */
 public class ComponentContextAdapter implements ComponentContext {
 public class ComponentContextAdapter implements ComponentContext {
+    private static class MockDictionary extends Dictionary {
+
         @Override
         @Override
-    public Dictionary getProperties() {
+        public int size() {
+            return 0;
+        }
+
+        @Override
+        public boolean isEmpty() {
+            return false;
+        }
+
+        @Override
+        public Enumeration keys() {
             return null;
             return null;
         }
         }
 
 
         @Override
         @Override
+        public Enumeration elements() {
+            return null;
+        }
+
+        @Override
+        public Object get(Object key) {
+            return null;
+        }
+
+        @Override
+        public Object put(Object key, Object value) {
+            return null;
+        }
+
+        @Override
+        public Object remove(Object key) {
+            return null;
+        }
+    }
+
+    @Override
+    public Dictionary getProperties() {
+        return new MockDictionary();
+    }
+
+    @Override
     public Object locateService(String name) {
     public Object locateService(String name) {
         return null;
         return null;
     }
     }