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/*
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* Portions Copyright 2000-2007 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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/*
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*
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* (C) Copyright IBM Corp. 1999 All Rights Reserved.
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* Copyright 1997 The Open Group Research Institute. All rights reserved.
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*/
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package sun.security.krb5.internal;
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import sun.security.krb5.Confounder;
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public class LocalSeqNumber implements SeqNumber {
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private int lastSeqNumber;
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public LocalSeqNumber() {
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randInit();
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}
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public LocalSeqNumber(int start) {
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init(start);
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}
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public LocalSeqNumber(Integer start) {
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init(start.intValue());
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}
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public synchronized void randInit() {
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/*
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* Sequence numbers fall in the range 0 through 2^32 - 1 and wrap
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* to zero following the value 2^32 - 1.
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* Previous implementations used signed sequence numbers.
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* Workaround implementation incompatibilities by not generating
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* initial sequence numbers greater than 2^30, as done
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* in MIT distribution.
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*/
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// get the random confounder
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byte[] data = Confounder.bytes(4);
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data[0] = (byte)(data[0] & 0x3f);
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int result = ((data[3] & 0xff) |
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((data[2] & 0xff) << 8) |
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((data[1] & 0xff) << 16) |
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((data[0] & 0xff) << 24));
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if (result == 0) {
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result = 1;
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}
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lastSeqNumber = result;
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}
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public synchronized void init(int start) {
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lastSeqNumber = start;
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}
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public synchronized int current() {
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return lastSeqNumber;
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}
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public synchronized int next() {
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return lastSeqNumber + 1;
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}
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public synchronized int step() {
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return ++lastSeqNumber;
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}
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}
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