/* * Copyright (c) 2000, 2007, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * *  (C) Copyright IBM Corp. 1999 All Rights Reserved. *  Copyright 1997 The Open Group Research Institute.  All rights reserved. */ package sun.security.krb5.internal; import sun.security.krb5.Confounder; public class LocalSeqNumber implements SeqNumber {    private int lastSeqNumber;     public LocalSeqNumber() {        randInit();    }     public LocalSeqNumber(int start) {        init(start);    }     public LocalSeqNumber(Integer start) {        init(start.intValue());    }     public synchronized void randInit() {        /*         * Sequence numbers fall in the range 0 through 2^32 - 1 and wrap         * to zero following the value 2^32 - 1.         * Previous implementations used signed sequence numbers.         * Workaround implementation incompatibilities by not generating         * initial sequence numbers greater than 2^30, as done         * in MIT distribution.         */        // get the random confounder        byte[] data = Confounder.bytes(4);        data[0] = (byte)(data[0] & 0x3f);        int result = ((data[3] & 0xff) |                        ((data[2] & 0xff) << 8) |                        ((data[1] & 0xff) << 16) |                        ((data[0] & 0xff) << 24));        if (result == 0) {           result = 1;        }        lastSeqNumber = result;    }     public synchronized void init(int start) {        lastSeqNumber = start;    }     public synchronized int current() {        return lastSeqNumber;    }     public synchronized int next() {        return lastSeqNumber + 1;    }     public synchronized int step() {        return ++lastSeqNumber;    } }