001/*
002 * Copyright 2007-2022 Ping Identity Corporation
003 * All Rights Reserved.
004 */
005/*
006 * Copyright 2007-2022 Ping Identity Corporation
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *    http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020/*
021 * Copyright (C) 2007-2022 Ping Identity Corporation
022 *
023 * This program is free software; you can redistribute it and/or modify
024 * it under the terms of the GNU General Public License (GPLv2 only)
025 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
026 * as published by the Free Software Foundation.
027 *
028 * This program is distributed in the hope that it will be useful,
029 * but WITHOUT ANY WARRANTY; without even the implied warranty of
030 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
031 * GNU General Public License for more details.
032 *
033 * You should have received a copy of the GNU General Public License
034 * along with this program; if not, see <http://www.gnu.org/licenses>.
035 */
036package com.unboundid.ldap.sdk.controls;
037
038
039
040import com.unboundid.asn1.ASN1Element;
041import com.unboundid.asn1.ASN1Exception;
042import com.unboundid.asn1.ASN1Integer;
043import com.unboundid.asn1.ASN1OctetString;
044import com.unboundid.asn1.ASN1Sequence;
045import com.unboundid.ldap.sdk.Control;
046import com.unboundid.ldap.sdk.DecodeableControl;
047import com.unboundid.ldap.sdk.LDAPException;
048import com.unboundid.ldap.sdk.ResultCode;
049import com.unboundid.ldap.sdk.SearchResult;
050import com.unboundid.util.Debug;
051import com.unboundid.util.NotMutable;
052import com.unboundid.util.NotNull;
053import com.unboundid.util.Nullable;
054import com.unboundid.util.ThreadSafety;
055import com.unboundid.util.ThreadSafetyLevel;
056
057import static com.unboundid.ldap.sdk.controls.ControlMessages.*;
058
059
060
061/**
062 * This class provides an implementation of the simple paged results control as
063 * defined in <A HREF="http://www.ietf.org/rfc/rfc2696.txt">RFC 2696</A>.  It
064 * allows the client to iterate through a potentially large set of search
065 * results in subsets of a specified number of entries (i.e., "pages").
066 * <BR><BR>
067 * The same control encoding is used for both the request control sent by
068 * clients and the response control returned by the server.  It may contain
069 * two elements:
070 * <UL>
071 *   <LI>Size -- In a request control, this provides the requested page size,
072 *       which is the maximum number of entries that the server should return
073 *       in the next iteration of the search.  In a response control, it is an
074 *       estimate of the total number of entries that match the search
075 *       criteria.</LI>
076 *   <LI>Cookie -- A token which is used by the server to keep track of its
077 *       position in the set of search results.  The first request sent by the
078 *       client should not include a cookie, and the last response sent by the
079 *       server should not include a cookie.  For all other intermediate search
080 *       requests and responses,  the server will include a cookie value in its
081 *       response that the client should include in its next request.</LI>
082 * </UL>
083 * When the client wishes to use the paged results control, the first search
084 * request should include a version of the paged results request control that
085 * was created with a requested page size but no cookie.  The corresponding
086 * response from the server will include a version of the paged results control
087 * that may include an estimate of the total number of matching entries, and
088 * may also include a cookie.  The client should include this cookie in the
089 * next request (with the same set of search criteria) to retrieve the next page
090 * of results.  This process should continue until the response control returned
091 * by the server does not include a cookie, which indicates that the end of the
092 * result set has been reached.
093 * <BR><BR>
094 * Note that the simple paged results control is similar to the
095 * {@link VirtualListViewRequestControl} in that both allow the client to
096 * request that only a portion of the result set be returned at any one time.
097 * However, there are significant differences between them, including:
098 * <UL>
099 *   <LI>In order to use the virtual list view request control, it is also
100 *       necessary to use the {@link ServerSideSortRequestControl} to ensure
101 *       that the entries are sorted.  This is not a requirement for the
102 *       simple paged results control.</LI>
103 *   <LI>The simple paged results control may only be used to iterate
104 *       sequentially through the set of search results.  The virtual list view
105 *       control can retrieve pages out of order, can retrieve overlapping
106 *       pages, and can re-request pages that it had already retrieved.</LI>
107 * </UL>
108 * <H2>Example</H2>
109 * The following example demonstrates the use of the simple paged results
110 * control.  It will iterate through all users, retrieving up to 10 entries at a
111 * time:
112 * <PRE>
113 * // Perform a search to retrieve all users in the server, but only retrieving
114 * // ten at a time.
115 * int numSearches = 0;
116 * int totalEntriesReturned = 0;
117 * SearchRequest searchRequest = new SearchRequest("dc=example,dc=com",
118 *      SearchScope.SUB, Filter.createEqualityFilter("objectClass", "person"));
119 * ASN1OctetString resumeCookie = null;
120 * while (true)
121 * {
122 *   searchRequest.setControls(
123 *        new SimplePagedResultsControl(10, resumeCookie));
124 *   SearchResult searchResult = connection.search(searchRequest);
125 *   numSearches++;
126 *   totalEntriesReturned += searchResult.getEntryCount();
127 *   for (SearchResultEntry e : searchResult.getSearchEntries())
128 *   {
129 *     // Do something with each entry...
130 *   }
131 *
132 *   LDAPTestUtils.assertHasControl(searchResult,
133 *        SimplePagedResultsControl.PAGED_RESULTS_OID);
134 *   SimplePagedResultsControl responseControl =
135 *        SimplePagedResultsControl.get(searchResult);
136 *   if (responseControl.moreResultsToReturn())
137 *   {
138 *     // The resume cookie can be included in the simple paged results
139 *     // control included in the next search to get the next page of results.
140 *     resumeCookie = responseControl.getCookie();
141 *   }
142 *   else
143 *   {
144 *     break;
145 *   }
146 * }
147 * </PRE>
148 */
149@NotMutable()
150@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
151public final class SimplePagedResultsControl
152       extends Control
153       implements DecodeableControl
154{
155  /**
156   * The OID (1.2.840.113556.1.4.319) for the paged results control.
157   */
158  @NotNull public static final String PAGED_RESULTS_OID =
159       "1.2.840.113556.1.4.319";
160
161
162
163  /**
164   * The serial version UID for this serializable class.
165   */
166  private static final long serialVersionUID = 2186787148024999291L;
167
168
169
170  // The encoded cookie returned from the server (for a response control) or
171  // that should be included in the next request to the server (for a request
172  // control).
173  @NotNull private final ASN1OctetString cookie;
174
175  // The maximum requested page size (for a request control), or the estimated
176  // total result set size (for a response control).
177  private final int size;
178
179
180
181  /**
182   * Creates a new empty control instance that is intended to be used only for
183   * decoding controls via the {@code DecodeableControl} interface.
184   */
185  SimplePagedResultsControl()
186  {
187    size   = 0;
188    cookie = new ASN1OctetString();
189  }
190
191
192
193  /**
194   * Creates a new paged results control with the specified page size.  This
195   * version of the constructor should only be used when creating the first
196   * search as part of the set of paged results.  Subsequent searches to
197   * retrieve additional pages should use the response control returned by the
198   * server in their next request, until the response control returned by the
199   * server does not include a cookie.
200   *
201   * @param  pageSize  The maximum number of entries that the server should
202   *                   return in the first page.
203   */
204  public SimplePagedResultsControl(final int pageSize)
205  {
206    super(PAGED_RESULTS_OID, false, encodeValue(pageSize, null));
207
208    size   = pageSize;
209    cookie = new ASN1OctetString();
210  }
211
212
213
214  /**
215   * Creates a new paged results control with the specified page size.  This
216   * version of the constructor should only be used when creating the first
217   * search as part of the set of paged results.  Subsequent searches to
218   * retrieve additional pages should use the response control returned by the
219   * server in their next request, until the response control returned by the
220   * server does not include a cookie.
221   *
222   * @param  pageSize    The maximum number of entries that the server should
223   *                     return in the first page.
224   * @param  isCritical  Indicates whether this control should be marked
225   *                     critical.
226   */
227  public SimplePagedResultsControl(final int pageSize, final boolean isCritical)
228  {
229    super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, null));
230
231    size   = pageSize;
232    cookie = new ASN1OctetString();
233  }
234
235
236
237  /**
238   * Creates a new paged results control with the specified page size and the
239   * provided cookie.  This version of the constructor should be used to
240   * continue iterating through an existing set of results, but potentially
241   * using a different page size.
242   *
243   * @param  pageSize  The maximum number of entries that the server should
244   *                   return in the next page of the results.
245   * @param  cookie    The cookie provided by the server after returning the
246   *                   previous page of results, or {@code null} if this request
247   *                   will retrieve the first page of results.
248   */
249  public SimplePagedResultsControl(final int pageSize,
250                                   @Nullable final ASN1OctetString cookie)
251  {
252    super(PAGED_RESULTS_OID, false, encodeValue(pageSize, cookie));
253
254    size = pageSize;
255
256    if (cookie == null)
257    {
258      this.cookie = new ASN1OctetString();
259    }
260    else
261    {
262      this.cookie = cookie;
263    }
264  }
265
266
267
268  /**
269   * Creates a new paged results control with the specified page size and the
270   * provided cookie.  This version of the constructor should be used to
271   * continue iterating through an existing set of results, but potentially
272   * using a different page size.
273   *
274   * @param  pageSize    The maximum number of entries that the server should
275   *                     return in the first page.
276   * @param  cookie      The cookie provided by the server after returning the
277   *                     previous page of results, or {@code null} if this
278   *                     request will retrieve the first page of results.
279   * @param  isCritical  Indicates whether this control should be marked
280   *                     critical.
281   */
282  public SimplePagedResultsControl(final int pageSize,
283                                   @Nullable final ASN1OctetString cookie,
284                                   final boolean isCritical)
285  {
286    super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, cookie));
287
288    size = pageSize;
289
290    if (cookie == null)
291    {
292      this.cookie = new ASN1OctetString();
293    }
294    else
295    {
296      this.cookie = cookie;
297    }
298  }
299
300
301
302  /**
303   * Creates a new paged results control from the control with the provided set
304   * of information.  This should be used to decode the paged results response
305   * control returned by the server with a page of results.
306   *
307   * @param  oid         The OID for the control.
308   * @param  isCritical  Indicates whether the control should be marked
309   *                     critical.
310   * @param  value       The encoded value for the control.  This may be
311   *                     {@code null} if no value was provided.
312   *
313   * @throws  LDAPException  If the provided control cannot be decoded as a
314   *                         simple paged results control.
315   */
316  public SimplePagedResultsControl(@NotNull final String oid,
317                                   final boolean isCritical,
318                                   @Nullable final ASN1OctetString value)
319         throws LDAPException
320  {
321    super(oid, isCritical, value);
322
323    if (value == null)
324    {
325      throw new LDAPException(ResultCode.DECODING_ERROR,
326                              ERR_PAGED_RESULTS_NO_VALUE.get());
327    }
328
329    final ASN1Sequence valueSequence;
330    try
331    {
332      final ASN1Element valueElement = ASN1Element.decode(value.getValue());
333      valueSequence = ASN1Sequence.decodeAsSequence(valueElement);
334    }
335    catch (final ASN1Exception ae)
336    {
337      Debug.debugException(ae);
338      throw new LDAPException(ResultCode.DECODING_ERROR,
339                              ERR_PAGED_RESULTS_VALUE_NOT_SEQUENCE.get(ae), ae);
340    }
341
342    final ASN1Element[] valueElements = valueSequence.elements();
343    if (valueElements.length != 2)
344    {
345      throw new LDAPException(ResultCode.DECODING_ERROR,
346                              ERR_PAGED_RESULTS_INVALID_ELEMENT_COUNT.get(
347                                   valueElements.length));
348    }
349
350    try
351    {
352      size = ASN1Integer.decodeAsInteger(valueElements[0]).intValue();
353    }
354    catch (final ASN1Exception ae)
355    {
356      Debug.debugException(ae);
357      throw new LDAPException(ResultCode.DECODING_ERROR,
358                              ERR_PAGED_RESULTS_FIRST_NOT_INTEGER.get(ae), ae);
359    }
360
361    cookie = ASN1OctetString.decodeAsOctetString(valueElements[1]);
362  }
363
364
365
366  /**
367   * {@inheritDoc}
368   */
369  @Override()
370  @NotNull()
371  public SimplePagedResultsControl decodeControl(@NotNull final String oid,
372              final boolean isCritical,
373              @Nullable final ASN1OctetString value)
374         throws LDAPException
375  {
376    return new SimplePagedResultsControl(oid, isCritical, value);
377  }
378
379
380
381  /**
382   * Extracts a simple paged results response control from the provided result.
383   *
384   * @param  result  The result from which to retrieve the simple paged results
385   *                 response control.
386   *
387   * @return  The simple paged results response control contained in the
388   *          provided result, or {@code null} if the result did not contain a
389   *          simple paged results response control.
390   *
391   * @throws  LDAPException  If a problem is encountered while attempting to
392   *                         decode the simple paged results response control
393   *                         contained in the provided result.
394   */
395  @Nullable()
396  public static SimplePagedResultsControl get(
397                     @NotNull final SearchResult result)
398         throws LDAPException
399  {
400    final Control c = result.getResponseControl(PAGED_RESULTS_OID);
401    if (c == null)
402    {
403      return null;
404    }
405
406    if (c instanceof SimplePagedResultsControl)
407    {
408      return (SimplePagedResultsControl) c;
409    }
410    else
411    {
412      return new SimplePagedResultsControl(c.getOID(), c.isCritical(),
413           c.getValue());
414    }
415  }
416
417
418
419  /**
420   * Encodes the provided information into an octet string that can be used as
421   * the value for this control.
422   *
423   * @param  pageSize  The maximum number of entries that the server should
424   *                   return in the next page of the results.
425   * @param  cookie    The cookie provided by the server after returning the
426   *                   previous page of results, or {@code null} if this request
427   *                   will retrieve the first page of results.
428   *
429   * @return  An ASN.1 octet string that can be used as the value for this
430   *          control.
431   */
432  @NotNull()
433  private static ASN1OctetString encodeValue(final int pageSize,
434                      @Nullable final ASN1OctetString cookie)
435  {
436    final ASN1Element[] valueElements;
437    if (cookie == null)
438    {
439      valueElements = new ASN1Element[]
440      {
441        new ASN1Integer(pageSize),
442        new ASN1OctetString()
443      };
444    }
445    else
446    {
447      valueElements = new ASN1Element[]
448      {
449        new ASN1Integer(pageSize),
450        cookie
451      };
452    }
453
454    return new ASN1OctetString(new ASN1Sequence(valueElements).encode());
455  }
456
457
458
459  /**
460   * Retrieves the size for this paged results control.  For a request control,
461   * it may be used to specify the number of entries that should be included in
462   * the next page of results.  For a response control, it may be used to
463   * specify the estimated number of entries in the complete result set.
464   *
465   * @return  The size for this paged results control.
466   */
467  public int getSize()
468  {
469    return size;
470  }
471
472
473
474  /**
475   * Retrieves the cookie for this control, which may be used in a subsequent
476   * request to resume reading entries from the next page of results.  The
477   * value should have a length of zero when used to retrieve the first page of
478   * results for a given search, and also in the response from the server when
479   * there are no more entries to send.  It should be non-empty for all other
480   * conditions.
481   *
482   * @return  The cookie for this control, or an empty cookie (with a value
483   *          length of zero) if there is none.
484   */
485  @NotNull()
486  public ASN1OctetString getCookie()
487  {
488    return cookie;
489  }
490
491
492
493  /**
494   * Indicates whether there are more results to return as part of this search.
495   *
496   * @return  {@code true} if there are more results to return, or
497   *          {@code false} if not.
498   */
499  public boolean moreResultsToReturn()
500  {
501    return (cookie.getValue().length > 0);
502  }
503
504
505
506  /**
507   * {@inheritDoc}
508   */
509  @Override()
510  @NotNull()
511  public String getControlName()
512  {
513    return INFO_CONTROL_NAME_PAGED_RESULTS.get();
514  }
515
516
517
518  /**
519   * {@inheritDoc}
520   */
521  @Override()
522  public void toString(@NotNull final StringBuilder buffer)
523  {
524    buffer.append("SimplePagedResultsControl(pageSize=");
525    buffer.append(size);
526    buffer.append(", isCritical=");
527    buffer.append(isCritical());
528    buffer.append(')');
529  }
530}