Refactored the ARP cache logic out of ProxyArpManager and into its own class to make the code clearer. Moved to using MACAddress objects in the ProxyArpManager APIs and implementation which prevents us having to pass byte arrays around and are safer as MACAddress prevents a rogue client changing the MAC address for everyone
diff --git a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCache.java b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCache.java
new file mode 100644
index 0000000..8b9c65a
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCache.java
@@ -0,0 +1,87 @@
+package net.onrc.onos.ofcontroller.proxyarp;
+
+import java.net.InetAddress;
+import java.util.HashMap;
+import java.util.Map;
+
+import net.floodlightcontroller.util.MACAddress;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implements a basic ARP cache which maps IPv4 addresses to MAC addresses.
+ * Mappings time out after a short period of time (currently 1 min). We don't
+ * try and refresh the mapping before the entry times out because as a controller
+ * we don't know if the mapping is still needed.
+ *
+ */
+
+/* TODO clean out old ARP entries out of the cache periodically. We currently
+ * don't do this which means the cache memory size will never decrease. We already
+ * have a periodic thread that can be used to do this in ProxyArpManager.
+ */
+public class ArpCache {
+ private final static Logger log = LoggerFactory.getLogger(ArpCache.class);
+
+ private final long ARP_ENTRY_TIMEOUT = 60000; //ms (1 min)
+
+ //Protected by locking on the ArpCache object
+ private final Map<InetAddress, ArpCacheEntry> arpCache;
+
+ private static class ArpCacheEntry {
+ private final MACAddress macAddress;
+ private long timeLastSeen;
+
+ public ArpCacheEntry(MACAddress macAddress) {
+ this.macAddress = macAddress;
+ this.timeLastSeen = System.currentTimeMillis();
+ }
+
+ public MACAddress getMacAddress() {
+ return macAddress;
+ }
+
+ public long getTimeLastSeen() {
+ return timeLastSeen;
+ }
+
+ public void setTimeLastSeen(long time){
+ timeLastSeen = time;
+ }
+ }
+
+ public ArpCache() {
+ arpCache = new HashMap<InetAddress, ArpCacheEntry>();
+ }
+
+ public synchronized MACAddress lookup(InetAddress ipAddress){
+ ArpCacheEntry arpEntry = arpCache.get(ipAddress);
+
+ if (arpEntry == null){
+ return null;
+ }
+
+ if (System.currentTimeMillis() - arpEntry.getTimeLastSeen()
+ > ARP_ENTRY_TIMEOUT){
+ //Entry has timed out so we'll remove it and return null
+ log.trace("Removing expired ARP entry for {}", ipAddress.getHostAddress());
+
+ arpCache.remove(ipAddress);
+ return null;
+ }
+
+ return arpEntry.getMacAddress();
+ }
+
+ public synchronized void update(InetAddress ipAddress, MACAddress macAddress){
+ ArpCacheEntry arpEntry = arpCache.get(ipAddress);
+
+ if (arpEntry != null && arpEntry.getMacAddress().equals(macAddress)){
+ arpEntry.setTimeLastSeen(System.currentTimeMillis());
+ }
+ else {
+ arpCache.put(ipAddress, new ArpCacheEntry(macAddress));
+ }
+ }
+}