| /* |
| * Copyright (c) 2000, 2006, 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. |
| */ |
| |
| package sun.security.jgss; |
| |
| import org.ietf.jgss.MessageProp; |
| import java.util.LinkedList; |
| |
| /** |
| * A utility class that implements a number list that keeps track of which |
| * tokens have arrived by storing their token numbers in the list. It helps |
| * detect old tokens, out of sequence tokens, and duplicate tokens. |
| * |
| * Each element of the list is an interval [a, b]. Its existence in the |
| * list implies that all token numbers in the range a, a+1, ..., b-1, b |
| * have arrived. Gaps in arrived token numbers are represented by the |
| * numbers that fall in between two elements of the list. eg. {[a,b], |
| * [c,d]} indicates that the token numbers b+1, ..., c-1 have not arrived |
| * yet. |
| * |
| * The maximum number of intervals that we keep track of is |
| * MAX_INTERVALS. Thus if there are too many gaps, then some of the older |
| * sequence numbers are deleted from the list. The earliest sequence number |
| * that exists in the list is the windowStart. The next expected sequence |
| * number, or expectedNumber, is one greater than the latest sequence |
| * number in the list. |
| * |
| * The list keeps track the first token number that should have arrived |
| * (initNumber) so that it is able to detect if certain numbers occur after |
| * the first valid token number but before windowStart. That would happen |
| * if the number of elements (intervals) exceeds MAX_INTERVALS and some |
| * initial elements had to be deleted. |
| * |
| * The working of the list is optimized for the normal case where the |
| * tokens arrive in sequence. |
| * |
| * @author Mayank Upadhyay |
| * @since 1.4 |
| */ |
| public class TokenTracker { |
| |
| static final int MAX_INTERVALS = 5; |
| |
| private int initNumber; |
| private int windowStart; |
| private int expectedNumber; |
| |
| private int windowStartIndex = 0; |
| |
| private LinkedList<Entry> list = new LinkedList<Entry>(); |
| |
| public TokenTracker(int initNumber) { |
| |
| this.initNumber = initNumber; |
| this.windowStart = initNumber; |
| this.expectedNumber = initNumber; |
| |
| // Make an entry with one less than the expected first token |
| Entry entry = new Entry(initNumber-1); |
| |
| list.add(entry); |
| } |
| |
| /** |
| * Returns the index for the entry into which this number will fit. If |
| * there is none, it returns the index of the last interval |
| * which precedes this number. It returns -1 if the number needs to be |
| * a in a new interval ahead of the whole list. |
| */ |
| private int getIntervalIndex(int number) { |
| Entry entry = null; |
| int i; |
| // Start from the rear to optimize for the normal case |
| for (i = list.size() - 1; i >= 0; i--) { |
| entry = list.get(i); |
| if (entry.compareTo(number) <= 0) |
| break; |
| } |
| return i; |
| } |
| |
| /** |
| * Sets the sequencing and replay information for the given token |
| * number. |
| * |
| * The following represents the number line with positions of |
| * initNumber, windowStart, expectedNumber marked on it. Regions in |
| * between them show the different sequencing and replay state |
| * possibilites for tokens that fall in there. |
| * |
| * (1) windowStart |
| * initNumber expectedNumber |
| * | | |
| * ---|---------------------------|--- |
| * GAP | DUP/UNSEQ | GAP |
| * |
| * |
| * (2) initNumber windowStart expectedNumber |
| * | | | |
| * ---|---------------|--------------|--- |
| * GAP | OLD | DUP/UNSEQ | GAP |
| * |
| * |
| * (3) windowStart |
| * expectedNumber initNumber |
| * | | |
| * ---|---------------------------|--- |
| * DUP/UNSEQ | GAP | DUP/UNSEQ |
| * |
| * |
| * (4) expectedNumber initNumber windowStart |
| * | | | |
| * ---|---------------|--------------|--- |
| * DUP/UNSEQ | GAP | OLD | DUP/UNSEQ |
| * |
| * |
| * |
| * (5) windowStart expectedNumber initNumber |
| * | | | |
| * ---|---------------|--------------|--- |
| * OLD | DUP/UNSEQ | GAP | OLD |
| * |
| * |
| * |
| * (This analysis leaves out the possibility that expectedNumber passes |
| * initNumber after wrapping around. That may be added later.) |
| */ |
| synchronized public final void getProps(int number, MessageProp prop) { |
| |
| boolean gap = false; |
| boolean old = false; |
| boolean unsequenced = false; |
| boolean duplicate = false; |
| |
| // System.out.println("\n\n=========="); |
| // System.out.println("TokenTracker.getProps(): number=" + number); |
| // System.out.println(toString()); |
| |
| int pos = getIntervalIndex(number); |
| Entry entry = null; |
| if (pos != -1) |
| entry = list.get(pos); |
| |
| // Optimize for the expected case: |
| |
| if (number == expectedNumber) { |
| expectedNumber++; |
| } else { |
| |
| // Next trivial case is to check for duplicate |
| if (entry != null && entry.contains(number)) |
| duplicate = true; |
| else { |
| |
| if (expectedNumber >= initNumber) { |
| |
| // Cases (1) and (2) |
| |
| if (number > expectedNumber) { |
| gap = true; |
| } else if (number >= windowStart) { |
| unsequenced = true; |
| } else if (number >= initNumber) { |
| old = true; |
| } else { |
| gap = true; |
| } |
| } else { |
| |
| // Cases (3), (4) and (5) |
| |
| if (number > expectedNumber) { |
| if (number < initNumber) { |
| gap = true; |
| } else if (windowStart >= initNumber) { |
| if (number >= windowStart) { |
| unsequenced = true; |
| } else |
| old = true; |
| } else { |
| old = true; |
| } |
| } else if (windowStart > expectedNumber) { |
| unsequenced = true; |
| } else if (number < windowStart) { |
| old = true; |
| } else |
| unsequenced = true; |
| } |
| } |
| } |
| |
| if (!duplicate && !old) |
| add(number, pos); |
| |
| if (gap) |
| expectedNumber = number+1; |
| |
| prop.setSupplementaryStates(duplicate, old, unsequenced, gap, |
| 0, null); |
| |
| // System.out.println("Leaving with state:"); |
| // System.out.println(toString()); |
| // System.out.println("==========\n"); |
| } |
| |
| /** |
| * Adds the number to the list just after the entry that is currently |
| * at position prevEntryPos. If prevEntryPos is -1, then the number |
| * will begin a new interval at the front of the list. |
| */ |
| private void add(int number, int prevEntryPos) { |
| |
| Entry entry; |
| Entry entryBefore = null; |
| Entry entryAfter = null; |
| |
| boolean appended = false; |
| boolean prepended = false; |
| |
| if (prevEntryPos != -1) { |
| entryBefore = list.get(prevEntryPos); |
| |
| // Can this number simply be added to the previous interval? |
| if (number == (entryBefore.getEnd() + 1)) { |
| entryBefore.setEnd(number); |
| appended = true; |
| } |
| } |
| |
| // Now check the interval that follows this number |
| |
| int nextEntryPos = prevEntryPos + 1; |
| if ((nextEntryPos) < list.size()) { |
| entryAfter = list.get(nextEntryPos); |
| |
| // Can this number simply be added to the next interval? |
| if (number == (entryAfter.getStart() - 1)) { |
| if (!appended) { |
| entryAfter.setStart(number); |
| } else { |
| // Merge the two entries |
| entryAfter.setStart(entryBefore.getStart()); |
| list.remove(prevEntryPos); |
| // Index of any entry following this gets decremented |
| if (windowStartIndex > prevEntryPos) |
| windowStartIndex--; |
| } |
| prepended = true; |
| } |
| } |
| |
| if (prepended || appended) |
| return; |
| |
| /* |
| * At this point we know that the number will start a new interval |
| * which needs to be added to the list. We might have to recyle an |
| * older entry in the list. |
| */ |
| |
| if (list.size() < MAX_INTERVALS) { |
| entry = new Entry(number); |
| if (prevEntryPos < windowStartIndex) |
| windowStartIndex++; // due to the insertion which will happen |
| } else { |
| /* |
| * Delete the entry that marks the start of the current window. |
| * The marker will automatically point to the next entry in the |
| * list when this happens. If the current entry is at the end |
| * of the list then set the marker to the start of the list. |
| */ |
| int oldWindowStartIndex = windowStartIndex; |
| if (windowStartIndex == (list.size() - 1)) |
| windowStartIndex = 0; |
| |
| entry = list.remove(oldWindowStartIndex); |
| windowStart = list.get(windowStartIndex).getStart(); |
| entry.setStart(number); |
| entry.setEnd(number); |
| |
| if (prevEntryPos >= oldWindowStartIndex) { |
| prevEntryPos--; // due to the deletion that just happened |
| } else { |
| /* |
| * If the start of the current window just moved from the |
| * end of the list to the front of the list, and if the new |
| * entry will be added to the front of the list, then |
| * the new entry is the actual window start. |
| * eg, Consider { [-10, -8], ..., [-6, -3], [3, 9]}. In |
| * this list, suppose the element [3, 9] is the start of |
| * the window and has to be deleted to make place to add |
| * [-12, -12]. The resultant list will be |
| * {[-12, -12], [-10, -8], ..., [-6, -3]} and the new start |
| * of the window should be the element [-12, -12], not |
| * [-10, -8] which succeeded [3, 9] in the old list. |
| */ |
| if (oldWindowStartIndex != windowStartIndex) { |
| // windowStartIndex is 0 at this point |
| if (prevEntryPos == -1) |
| // The new entry is going to the front |
| windowStart = number; |
| } else { |
| // due to the insertion which will happen: |
| windowStartIndex++; |
| } |
| } |
| } |
| |
| // Finally we are ready to actually add to the list at index |
| // 'prevEntryPos+1' |
| |
| list.add(prevEntryPos+1, entry); |
| } |
| |
| public String toString() { |
| StringBuffer buf = new StringBuffer("TokenTracker: "); |
| buf.append(" initNumber=").append(initNumber); |
| buf.append(" windowStart=").append(windowStart); |
| buf.append(" expectedNumber=").append(expectedNumber); |
| buf.append(" windowStartIndex=").append(windowStartIndex); |
| buf.append("\n\tIntervals are: {"); |
| for (int i = 0; i < list.size(); i++) { |
| if (i != 0) |
| buf.append(", "); |
| buf.append(list.get(i).toString()); |
| } |
| buf.append('}'); |
| return buf.toString(); |
| } |
| |
| /** |
| * An entry in the list that represents the sequence of received |
| * tokens. Each entry is actaully an interval of numbers, all of which |
| * have been received. |
| */ |
| class Entry { |
| |
| private int start; |
| private int end; |
| |
| Entry(int number) { |
| start = number; |
| end = number; |
| } |
| |
| /** |
| * Returns -1 if this interval represented by this entry precedes |
| * the number, 0 if the the number is contained in the interval, |
| * and -1 if the interval occurs after the number. |
| */ |
| final int compareTo(int number) { |
| if (start > number) |
| return 1; |
| else if (end < number) |
| return -1; |
| else |
| return 0; |
| } |
| |
| final boolean contains(int number) { |
| return (number >= start && |
| number <= end); |
| } |
| |
| final void append(int number) { |
| if (number == (end + 1)) |
| end = number; |
| } |
| |
| final void setInterval(int start, int end) { |
| this.start = start; |
| this.end = end; |
| } |
| |
| final void setEnd(int end) { |
| this.end = end; |
| } |
| |
| final void setStart(int start) { |
| this.start = start; |
| } |
| |
| final int getStart() { |
| return start; |
| } |
| |
| final int getEnd() { |
| return end; |
| } |
| |
| public String toString() { |
| return ("[" + start + ", " + end + "]"); |
| } |
| |
| } |
| } |
