[Falcon] link discovery -

- safety checks against fingerprint being null
- checks for foreign fingerprint and probe message origin

Change-Id: I2f3e491802afc2091335bd25fcf24865293bde10

@@ -38,6 +38,9 @@ import com.google.common.collect.Sets;
  */
 public final class ClusterMetadata {
 
+    // Name to use when the ClusterMetadataService is in transient state
+    public static final String NO_NAME = "";
+
     private String name;
     private Set<ControllerNode> nodes;
     private Set<Partition> partitions;

@@ -17,6 +17,7 @@ package org.onosproject.provider.lldp.impl;
 
 import org.onosproject.mastership.MastershipService;
 import org.onosproject.net.LinkKey;
+import org.onosproject.net.device.DeviceService;
 import org.onosproject.net.link.LinkProviderService;
 import org.onosproject.net.packet.PacketService;
 
@@ -47,6 +48,13 @@ interface DiscoveryContext {
     PacketService packetService();
 
     /**
+     * Returns the DeviceService reference.
+     *
+     * @return the device service interface
+     */
+    DeviceService deviceService();
+
+    /**
      * Returns the probe rate in millis.
      *
      * @return probe rate

@@ -43,6 +43,7 @@ import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.onosproject.net.PortNumber.portNumber;
 import static org.onosproject.net.flow.DefaultTrafficTreatment.builder;
 import static org.slf4j.LoggerFactory.getLogger;
+import static org.onosproject.cluster.ClusterMetadata.NO_NAME;
 
 /**
  * Run discovery process from a physical switch. Ports are initially labeled as
@@ -159,6 +160,10 @@ class LinkDiscovery implements TimerTask {
 
         ONOSLLDP onoslldp = ONOSLLDP.parseONOSLLDP(eth);
         if (onoslldp != null) {
+            if (notMy(onoslldp)) {
+                return true;
+            }
+
             PortNumber srcPort = portNumber(onoslldp.getPort());
             PortNumber dstPort = packetContext.inPacket().receivedFrom().port();
             DeviceId srcDeviceId = DeviceId.deviceId(onoslldp.getDeviceString());
@@ -182,6 +187,26 @@ class LinkDiscovery implements TimerTask {
         return false;
     }
 
+    // true if *NOT* this cluster's own probe.
+    private boolean notMy(ONOSLLDP onoslldp) {
+        if (onoslldp.getDomainTLV() == null) {
+            // not finger-printed - but we can check the source
+            DeviceId src = DeviceId.deviceId(onoslldp.getDeviceString());
+            if (context.deviceService().getDevice(src) == null) {
+                return true;
+            }
+            return false;
+        }
+
+        String us = context.fingerprint();
+        String them = onoslldp.getDomainString();
+        // if: Our and/or their MetadataService in poorly state, conservative 'yes'
+        if (NO_NAME.equals(us) || NO_NAME.equals(them)) {
+            return true;
+        } else {
+            return !us.equals(them);
+        }
+    }
 
     /**
      * Execute this method every t milliseconds. Loops over all ports

@@ -27,6 +27,7 @@ import static org.onosproject.net.config.basics.SubjectFactories.APP_SUBJECT_FAC
 import static org.onosproject.net.config.basics.SubjectFactories.CONNECT_POINT_SUBJECT_FACTORY;
 import static org.onosproject.net.config.basics.SubjectFactories.DEVICE_SUBJECT_FACTORY;
 import static org.slf4j.LoggerFactory.getLogger;
+import static org.onosproject.cluster.ClusterMetadata.NO_NAME;
 
 import java.util.Dictionary;
 import java.util.EnumSet;
@@ -47,6 +48,7 @@ import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.onlab.packet.Ethernet;
 import org.onlab.util.Tools;
 import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.cluster.ClusterMetadata;
 import org.onosproject.cluster.ClusterMetadataService;
 import org.onosproject.cluster.ClusterService;
 import org.onosproject.core.ApplicationId;
@@ -426,6 +428,7 @@ public class LldpLinkProvider extends AbstractProvider implements LinkProvider {
             removeDevice(device.id());
             return Optional.empty();
         }
+
         LinkDiscovery ld = discoverers.computeIfAbsent(device.id(),
                                      did -> new LinkDiscovery(device, context));
         if (isFingerprinted(device.id())) {
@@ -749,7 +752,13 @@ public class LldpLinkProvider extends AbstractProvider implements LinkProvider {
 
         @Override
         public String fingerprint() {
-            return clusterMetadataService.getClusterMetadata().getName();
+            ClusterMetadata mdata = clusterMetadataService.getClusterMetadata();
+            return mdata == null ? NO_NAME : mdata.getName();
+        }
+
+        @Override
+        public DeviceService deviceService() {
+            return deviceService;
         }
     }