Change IP address mask according to the prefix when setting the IP forwarding rule.

Change-Id: Ic0f8fb43913473c622336de0dcf3e0751ba01d65
diff --git a/src/main/java/net/onrc/onos/core/matchaction/match/Ipv4Match.java b/src/main/java/net/onrc/onos/core/matchaction/match/Ipv4Match.java
index 5ed8c3a..a6d1bff 100644
--- a/src/main/java/net/onrc/onos/core/matchaction/match/Ipv4Match.java
+++ b/src/main/java/net/onrc/onos/core/matchaction/match/Ipv4Match.java
@@ -1,5 +1,6 @@
 package net.onrc.onos.core.matchaction.match;
 
+import net.onrc.onos.core.util.IPv4;
 import net.onrc.onos.core.util.IPv4Net;
 
 public class Ipv4Match implements Match {
@@ -8,6 +9,14 @@
 
     public Ipv4Match(String ipAddressSlash) {
         this.dstIp = new IPv4Net(ipAddressSlash);
+
+        IPv4 ip = dstIp.address();
+        short prefLen = dstIp.prefixLen();
+        int mask = ~((1 << (32 - prefLen)) - 1);;
+        int newIpInt = ip.value() & mask;
+        IPv4 newIp = new IPv4(newIpInt);
+
+        this.dstIp = new IPv4Net(newIp, prefLen);
     }
 
     public IPv4Net getDestination() {