Fix a bug in CIDR.contains(InetAddress) implementations

Related issue: #2767

Motivation:

CIDR.contains(InetAddress) implementations should always return true
when the CIDR's prefix length is 0.

Modifications:

- Make CIDR.contains(InetAddress) return true if the current cidrMask is
  0
- Add tests

Result:

Fixed the issue #2767

src/main/java/org/jboss/netty/handler/ipfilter/CIDR4.java

@@ -89,6 +89,14 @@ public int compareTo(CIDR arg) {
 
     @Override
     public boolean contains(InetAddress inetAddress) {
+        if (inetAddress == null) {
+            throw new NullPointerException("inetAddress");
+        }
+
+        if (cidrMask == 0) {
+            return true;
+        }
+
         int search = ipv4AddressToInt(inetAddress);
         return search >= addressInt && search <= addressEndInt;
     }

src/main/java/org/jboss/netty/handler/ipfilter/CIDR6.java

@@ -93,6 +93,14 @@ public int compareTo(CIDR arg) {
 
     @Override
     public boolean contains(InetAddress inetAddress) {
+        if (inetAddress == null) {
+            throw new NullPointerException("inetAddress");
+        }
+
+        if (cidrMask == 0) {
+            return true;
+        }
+
         BigInteger search = ipv6AddressToBigInteger(inetAddress);
         return search.compareTo(addressBigInt) >= 0 && search.compareTo(addressEndBigInt) <= 0;
     }

src/test/java/org/jboss/netty/handler/ipfilter/IpFilterRuleTest.java

@@ -246,6 +246,15 @@ public void testIpFilterRule() throws Exception {
         addr = new InetSocketAddress(InetAddress.getByName(InetAddress.getLocalHost().getHostName()), 8080);
         assertTrue(accept(h, addr));
 
+        h.clear();
+        h.addAll(new IpFilterRuleList("+c:0.0.0.0/0, -n:*"));
+        addr = new InetSocketAddress("91.114.240.43", 8080);
+        assertTrue(accept(h, addr));
+        addr = new InetSocketAddress("10.0.0.3", 8080);
+        assertTrue(accept(h, addr));
+        addr = new InetSocketAddress("192.168.93.2", 8080);
+        assertTrue(accept(h, addr));
+
         h.clear();
         h.addAll(new IpFilterRuleList(""));
         addr = new InetSocketAddress(InetAddress.getLocalHost(), 8080);
@@ -262,7 +271,6 @@ public void testIpFilterRule() throws Exception {
         assertTrue(accept(h, addr));
         addr = new InetSocketAddress(InetAddress.getByName(InetAddress.getLocalHost().getHostName()), 8080);
         assertTrue(accept(h, addr));
-
     }
 
 }