Add some unit tests for utility methods

core/src/main/java/org/elasticsearch/common/network/NetworkUtils.java

@@ -54,9 +54,9 @@ private NetworkUtils() {}
     static final boolean PREFER_V4 = Boolean.parseBoolean(System.getProperty("java.net.preferIPv4Stack", "true")); 
 
     /** Sorts an address by preference. This way code like publishing can just pick the first one */
-    private static int sortKey(InetAddress address) {
+    static int sortKey(InetAddress address, boolean prefer_v4) {
         int key = address.getAddress().length;
-        if (PREFER_V4 == false) {
+        if (prefer_v4 == false) {
             key = -key;
         }
 
@@ -88,7 +88,7 @@ private static void sortAddresses(List<InetAddress> list) {
         Collections.sort(list, new Comparator<InetAddress>() {
             @Override
             public int compare(InetAddress left, InetAddress right) {
-                int cmp = Integer.compare(sortKey(left), sortKey(right));
+                int cmp = Integer.compare(sortKey(left, PREFER_V4), sortKey(right, PREFER_V4));
                 if (cmp == 0) {
                     cmp = new BytesRef(left.getAddress()).compareTo(new BytesRef(right.getAddress()));
                 }

core/src/test/java/org/elasticsearch/common/network/NetworkUtilsTests.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.network;
+
+import org.elasticsearch.test.ESTestCase;
+
+import java.net.InetAddress;
+
+/**
+ * Tests for network utils. Please avoid using any methods that cause DNS lookups!
+ */
+public class NetworkUtilsTests extends ESTestCase {
+
+    /**
+     * test sort key order respects PREFER_IPV4
+     */
+    public void testSortKey() throws Exception {
+        InetAddress localhostv4 = InetAddress.getByName("127.0.0.1");
+        InetAddress localhostv6 = InetAddress.getByName("::1");
+        assertTrue(NetworkUtils.sortKey(localhostv4, true) < NetworkUtils.sortKey(localhostv6, true));
+        assertTrue(NetworkUtils.sortKey(localhostv6, false) < NetworkUtils.sortKey(localhostv4, false));
+    }
+
+    /**
+     * test ordinary addresses sort before private addresses
+     */
+    public void testSortKeySiteLocal() throws Exception {
+        InetAddress siteLocal = InetAddress.getByName("172.16.0.1");
+        assert siteLocal.isSiteLocalAddress();
+        InetAddress ordinary = InetAddress.getByName("192.192.192.192");
+        assertTrue(NetworkUtils.sortKey(ordinary, true) < NetworkUtils.sortKey(siteLocal, true));
+        assertTrue(NetworkUtils.sortKey(ordinary, false) < NetworkUtils.sortKey(siteLocal, false));
+
+        InetAddress siteLocal6 = InetAddress.getByName("fec0::1");
+        assert siteLocal6.isSiteLocalAddress();
+        InetAddress ordinary6 = InetAddress.getByName("fddd::1");
+        assertTrue(NetworkUtils.sortKey(ordinary6, true) < NetworkUtils.sortKey(siteLocal6, true));
+        assertTrue(NetworkUtils.sortKey(ordinary6, false) < NetworkUtils.sortKey(siteLocal6, false));
+    }
+
+    /**
+     * test private addresses sort before link local addresses
+     */
+    public void testSortKeyLinkLocal() throws Exception {
+        InetAddress linkLocal = InetAddress.getByName("fe80::1");
+        assert linkLocal.isLinkLocalAddress();
+        InetAddress ordinary = InetAddress.getByName("fddd::1");
+        assertTrue(NetworkUtils.sortKey(ordinary, true) < NetworkUtils.sortKey(linkLocal, true));
+        assertTrue(NetworkUtils.sortKey(ordinary, false) < NetworkUtils.sortKey(linkLocal, false));
+    }
+
+    /**
+     * Test filtering out ipv4/ipv6 addresses
+     */
+    public void testFilter() throws Exception {
+        InetAddress addresses[] = { InetAddress.getByName("::1"), InetAddress.getByName("127.0.0.1") };
+        assertArrayEquals(new InetAddress[] { InetAddress.getByName("127.0.0.1") }, NetworkUtils.filterIPV4(addresses));
+        assertArrayEquals(new InetAddress[] { InetAddress.getByName("::1") }, NetworkUtils.filterIPV6(addresses));
+    }
+}