use port range in LdapServerTest

Author: Vladimir Kotal

plugins/src/test/java/opengrok/auth/plugin/LdapServerTest.java

@@ -25,13 +25,15 @@
 import opengrok.auth.plugin.ldap.LdapServer;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
+import org.opengrok.web.api.v1.controller.PortChecker;
 
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.net.URISyntaxException;
 import java.net.UnknownHostException;
+import java.util.Random;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -79,9 +81,24 @@ public void testSetGetUsername() {
 
     @Test
     public void testIsReachable() throws IOException, InterruptedException, URISyntaxException {
-        // Start simple TCP server on port 6336. It has to be > 1024 to avoid BindException
-        // due to permission denied.
-        int testPort = 6336;
+        final int testPortBase = 6336;    // It has to be > 1024 to avoid BindException due to permission denied.
+        final int randomRange = 49152;
+        int triesCount = 0;
+        final int MAX_PORT_TRIES = 20;
+        Random rand = new Random();
+        int testPort;
+        while (true) {
+            testPort = testPortBase + rand.nextInt(randomRange);
+            if (PortChecker.available(testPort)) {
+                break;
+            }
+            if (++triesCount > MAX_PORT_TRIES) {
+                throw new RuntimeException("Could not find an available port after " +
+                        MAX_PORT_TRIES + " tries");
+            }
+        }
+
+        // Start simple TCP server on test port.
         InetAddress localhostAddr = InetAddress.getLocalHost();
         ServerSocket serverSocket = new ServerSocket(testPort, 1, localhostAddr);
         Thread thread = new Thread(() -> {
@@ -108,7 +125,7 @@ public void testIsReachable() throws IOException, InterruptedException, URISynta
         assertNotNull(socket);
         assertTrue(socket.isConnected());
 
-        // Mock getAddresses() to return single localhost IP address.
+        // Mock getAddresses() to return single localhost IP address and getPort() to return the test port.
         LdapServer server = new LdapServer("ldaps://foo.bar.com");
         LdapServer serverSpy = Mockito.spy(server);
         Mockito.when(serverSpy.getAddresses(any())).thenReturn(new InetAddress[]{localhostAddr});

plugins/src/test/java/opengrok/auth/plugin/PortChecker.java

@@ -0,0 +1,75 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF 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.opengrok.web.api.v1.controller;
+
+import java.io.IOException;
+import java.net.DatagramSocket;
+import java.net.ServerSocket;
+
+/**
+ * Represents a helper for checking a network port, borrowed from Apache
+ * Usergrid's AvailablePortFinder.java.
+ */
+public class PortChecker {
+    /** The minimum number of server port number. */
+    public static final int MIN_PORT_NUMBER = 1;
+
+    /** The maximum number of server port number. */
+    public static final int MAX_PORT_NUMBER = 65535;
+
+    /**
+     * Checks to see if a specific port is available.
+     *
+     * @param port the port to check for availability
+     */
+    public static boolean available(int port) {
+        if (port < MIN_PORT_NUMBER || port > MAX_PORT_NUMBER) {
+            throw new IllegalArgumentException("Port out of valid range: " + port);
+        }
+
+        ServerSocket ss = null;
+        DatagramSocket ds = null;
+        try {
+            ss = new ServerSocket(port);
+            ss.setReuseAddress(true);
+            ds = new DatagramSocket(port);
+            ds.setReuseAddress(true);
+            return true;
+        } catch (IOException e) {
+            return false;
+        } finally {
+            if (ds != null) {
+                ds.close();
+            }
+
+            if (ss != null) {
+                try {
+                    ss.close();
+                } catch (IOException e) {
+                    /* should not be thrown */
+                }
+            }
+        }
+    }
+
+    /* private to enforce static */
+    private PortChecker() {
+    }
+}