J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Portions Copyright 2000-2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | /* |
| 27 | * |
| 28 | * (C) Copyright IBM Corp. 1999 All Rights Reserved. |
| 29 | * Copyright 1997 The Open Group Research Institute. All rights reserved. |
| 30 | */ |
| 31 | |
| 32 | package sun.security.krb5.internal; |
| 33 | |
| 34 | import sun.security.krb5.Confounder; |
| 35 | |
| 36 | public class LocalSeqNumber implements SeqNumber { |
| 37 | private int lastSeqNumber; |
| 38 | |
| 39 | public LocalSeqNumber() { |
| 40 | randInit(); |
| 41 | } |
| 42 | |
| 43 | public LocalSeqNumber(int start) { |
| 44 | init(start); |
| 45 | } |
| 46 | |
| 47 | public LocalSeqNumber(Integer start) { |
| 48 | init(start.intValue()); |
| 49 | } |
| 50 | |
| 51 | public synchronized void randInit() { |
| 52 | /* |
| 53 | * Sequence numbers fall in the range 0 through 2^32 - 1 and wrap |
| 54 | * to zero following the value 2^32 - 1. |
| 55 | * Previous implementations used signed sequence numbers. |
| 56 | * Workaround implementation incompatibilities by not generating |
| 57 | * initial sequence numbers greater than 2^30, as done |
| 58 | * in MIT distribution. |
| 59 | */ |
| 60 | // get the random confounder |
| 61 | byte[] data = Confounder.bytes(4); |
| 62 | data[0] = (byte)(data[0] & 0x3f); |
| 63 | int result = ((data[3] & 0xff) | |
| 64 | ((data[2] & 0xff) << 8) | |
| 65 | ((data[1] & 0xff) << 16) | |
| 66 | ((data[0] & 0xff) << 24)); |
| 67 | if (result == 0) { |
| 68 | result = 1; |
| 69 | } |
| 70 | lastSeqNumber = result; |
| 71 | } |
| 72 | |
| 73 | public synchronized void init(int start) { |
| 74 | lastSeqNumber = start; |
| 75 | } |
| 76 | |
| 77 | public synchronized int current() { |
| 78 | return lastSeqNumber; |
| 79 | } |
| 80 | |
| 81 | public synchronized int next() { |
| 82 | return lastSeqNumber + 1; |
| 83 | } |
| 84 | |
| 85 | public synchronized int step() { |
| 86 | return ++lastSeqNumber; |
| 87 | } |
| 88 | |
| 89 | } |