1 /*
2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 only, as
7  * published by the Free Software Foundation.
8  *
9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 
24 import java.util.Random;
25 
26 /**
27  * Dynamically allocates distinct ports from the ephemeral range 49152-65535
28  */
29 class PortAllocator {
30     private final static int LOWER_BOUND = 49152;
31     private final static int UPPER_BOUND = 65535;
32 
33     private final static Random RND = new Random(System.currentTimeMillis());
34 
allocatePorts(final int numPorts)35     static int[] allocatePorts(final int numPorts) {
36         int[] ports = new int[numPorts];
37         for (int i = 0; i < numPorts; i++) {
38             int port = -1;
39             while (port == -1) {
40                 port = RND.nextInt(UPPER_BOUND - LOWER_BOUND + 1) + LOWER_BOUND;
41                 for (int j = 0; j < i; j++) {
42                     if (ports[j] == port) {
43                         port = -1;
44                         break;
45                     }
46                 }
47             }
48             ports[i] = port;
49         }
50         return ports;
51     }
52 }
53