001/*
002 * Copyright 2007-2020 Ping Identity Corporation
003 * All Rights Reserved.
004 */
005/*
006 * Copyright 2007-2020 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) 2008-2020 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.ThreadSafety;
053import com.unboundid.util.ThreadSafetyLevel;
054
055import static com.unboundid.ldap.sdk.controls.ControlMessages.*;
056
057
058
059/**
060 * This class provides an implementation of the simple paged results control as
061 * defined in <A HREF="http://www.ietf.org/rfc/rfc2696.txt">RFC 2696</A>.  It
062 * allows the client to iterate through a potentially large set of search
063 * results in subsets of a specified number of entries (i.e., "pages").
064 * <BR><BR>
065 * The same control encoding is used for both the request control sent by
066 * clients and the response control returned by the server.  It may contain
067 * two elements:
068 * <UL>
069 *   <LI>Size -- In a request control, this provides the requested page size,
070 *       which is the maximum number of entries that the server should return
071 *       in the next iteration of the search.  In a response control, it is an
072 *       estimate of the total number of entries that match the search
073 *       criteria.</LI>
074 *   <LI>Cookie -- A token which is used by the server to keep track of its
075 *       position in the set of search results.  The first request sent by the
076 *       client should not include a cookie, and the last response sent by the
077 *       server should not include a cookie.  For all other intermediate search
078 *       requests and responses,  the server will include a cookie value in its
079 *       response that the client should include in its next request.</LI>
080 * </UL>
081 * When the client wishes to use the paged results control, the first search
082 * request should include a version of the paged results request control that
083 * was created with a requested page size but no cookie.  The corresponding
084 * response from the server will include a version of the paged results control
085 * that may include an estimate of the total number of matching entries, and
086 * may also include a cookie.  The client should include this cookie in the
087 * next request (with the same set of search criteria) to retrieve the next page
088 * of results.  This process should continue until the response control returned
089 * by the server does not include a cookie, which indicates that the end of the
090 * result set has been reached.
091 * <BR><BR>
092 * Note that the simple paged results control is similar to the
093 * {@link VirtualListViewRequestControl} in that both allow the client to
094 * request that only a portion of the result set be returned at any one time.
095 * However, there are significant differences between them, including:
096 * <UL>
097 *   <LI>In order to use the virtual list view request control, it is also
098 *       necessary to use the {@link ServerSideSortRequestControl} to ensure
099 *       that the entries are sorted.  This is not a requirement for the
100 *       simple paged results control.</LI>
101 *   <LI>The simple paged results control may only be used to iterate
102 *       sequentially through the set of search results.  The virtual list view
103 *       control can retrieve pages out of order, can retrieve overlapping
104 *       pages, and can re-request pages that it had already retrieved.</LI>
105 * </UL>
106 * <H2>Example</H2>
107 * The following example demonstrates the use of the simple paged results
108 * control.  It will iterate through all users, retrieving up to 10 entries at a
109 * time:
110 * <PRE>
111 * // Perform a search to retrieve all users in the server, but only retrieving
112 * // ten at a time.
113 * int numSearches = 0;
114 * int totalEntriesReturned = 0;
115 * SearchRequest searchRequest = new SearchRequest("dc=example,dc=com",
116 *      SearchScope.SUB, Filter.createEqualityFilter("objectClass", "person"));
117 * ASN1OctetString resumeCookie = null;
118 * while (true)
119 * {
120 *   searchRequest.setControls(
121 *        new SimplePagedResultsControl(10, resumeCookie));
122 *   SearchResult searchResult = connection.search(searchRequest);
123 *   numSearches++;
124 *   totalEntriesReturned += searchResult.getEntryCount();
125 *   for (SearchResultEntry e : searchResult.getSearchEntries())
126 *   {
127 *     // Do something with each entry...
128 *   }
129 *
130 *   LDAPTestUtils.assertHasControl(searchResult,
131 *        SimplePagedResultsControl.PAGED_RESULTS_OID);
132 *   SimplePagedResultsControl responseControl =
133 *        SimplePagedResultsControl.get(searchResult);
134 *   if (responseControl.moreResultsToReturn())
135 *   {
136 *     // The resume cookie can be included in the simple paged results
137 *     // control included in the next search to get the next page of results.
138 *     resumeCookie = responseControl.getCookie();
139 *   }
140 *   else
141 *   {
142 *     break;
143 *   }
144 * }
145 * </PRE>
146 */
147@NotMutable()
148@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
149public final class SimplePagedResultsControl
150       extends Control
151       implements DecodeableControl
152{
153  /**
154   * The OID (1.2.840.113556.1.4.319) for the paged results control.
155   */
156  public static final String PAGED_RESULTS_OID = "1.2.840.113556.1.4.319";
157
158
159
160  /**
161   * The serial version UID for this serializable class.
162   */
163  private static final long serialVersionUID = 2186787148024999291L;
164
165
166
167  // The encoded cookie returned from the server (for a response control) or
168  // that should be included in the next request to the server (for a request
169  // control).
170  private final ASN1OctetString cookie;
171
172  // The maximum requested page size (for a request control), or the estimated
173  // total result set size (for a response control).
174  private final int size;
175
176
177
178  /**
179   * Creates a new empty control instance that is intended to be used only for
180   * decoding controls via the {@code DecodeableControl} interface.
181   */
182  SimplePagedResultsControl()
183  {
184    size   = 0;
185    cookie = new ASN1OctetString();
186  }
187
188
189
190  /**
191   * Creates a new paged results control with the specified page size.  This
192   * version of the constructor should only be used when creating the first
193   * search as part of the set of paged results.  Subsequent searches to
194   * retrieve additional pages should use the response control returned by the
195   * server in their next request, until the response control returned by the
196   * server does not include a cookie.
197   *
198   * @param  pageSize  The maximum number of entries that the server should
199   *                   return in the first page.
200   */
201  public SimplePagedResultsControl(final int pageSize)
202  {
203    super(PAGED_RESULTS_OID, false, encodeValue(pageSize, null));
204
205    size   = pageSize;
206    cookie = new ASN1OctetString();
207  }
208
209
210
211  /**
212   * Creates a new paged results control with the specified page size.  This
213   * version of the constructor should only be used when creating the first
214   * search as part of the set of paged results.  Subsequent searches to
215   * retrieve additional pages should use the response control returned by the
216   * server in their next request, until the response control returned by the
217   * server does not include a cookie.
218   *
219   * @param  pageSize    The maximum number of entries that the server should
220   *                     return in the first page.
221   * @param  isCritical  Indicates whether this control should be marked
222   *                     critical.
223   */
224  public SimplePagedResultsControl(final int pageSize, final boolean isCritical)
225  {
226    super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, null));
227
228    size   = pageSize;
229    cookie = new ASN1OctetString();
230  }
231
232
233
234  /**
235   * Creates a new paged results control with the specified page size and the
236   * provided cookie.  This version of the constructor should be used to
237   * continue iterating through an existing set of results, but potentially
238   * using a different page size.
239   *
240   * @param  pageSize  The maximum number of entries that the server should
241   *                   return in the next page of the results.
242   * @param  cookie    The cookie provided by the server after returning the
243   *                   previous page of results, or {@code null} if this request
244   *                   will retrieve the first page of results.
245   */
246  public SimplePagedResultsControl(final int pageSize,
247                                   final ASN1OctetString cookie)
248  {
249    super(PAGED_RESULTS_OID, false, encodeValue(pageSize, cookie));
250
251    size = pageSize;
252
253    if (cookie == null)
254    {
255      this.cookie = new ASN1OctetString();
256    }
257    else
258    {
259      this.cookie = cookie;
260    }
261  }
262
263
264
265  /**
266   * Creates a new paged results control with the specified page size and the
267   * provided cookie.  This version of the constructor should be used to
268   * continue iterating through an existing set of results, but potentially
269   * using a different page size.
270   *
271   * @param  pageSize    The maximum number of entries that the server should
272   *                     return in the first page.
273   * @param  cookie      The cookie provided by the server after returning the
274   *                     previous page of results, or {@code null} if this
275   *                     request will retrieve the first page of results.
276   * @param  isCritical  Indicates whether this control should be marked
277   *                     critical.
278   */
279  public SimplePagedResultsControl(final int pageSize,
280                                   final ASN1OctetString cookie,
281                                   final boolean isCritical)
282  {
283    super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, cookie));
284
285    size = pageSize;
286
287    if (cookie == null)
288    {
289      this.cookie = new ASN1OctetString();
290    }
291    else
292    {
293      this.cookie = cookie;
294    }
295  }
296
297
298
299  /**
300   * Creates a new paged results control from the control with the provided set
301   * of information.  This should be used to decode the paged results response
302   * control returned by the server with a page of results.
303   *
304   * @param  oid         The OID for the control.
305   * @param  isCritical  Indicates whether the control should be marked
306   *                     critical.
307   * @param  value       The encoded value for the control.  This may be
308   *                     {@code null} if no value was provided.
309   *
310   * @throws  LDAPException  If the provided control cannot be decoded as a
311   *                         simple paged results control.
312   */
313  public SimplePagedResultsControl(final String oid, final boolean isCritical,
314                                   final ASN1OctetString value)
315         throws LDAPException
316  {
317    super(oid, isCritical, value);
318
319    if (value == null)
320    {
321      throw new LDAPException(ResultCode.DECODING_ERROR,
322                              ERR_PAGED_RESULTS_NO_VALUE.get());
323    }
324
325    final ASN1Sequence valueSequence;
326    try
327    {
328      final ASN1Element valueElement = ASN1Element.decode(value.getValue());
329      valueSequence = ASN1Sequence.decodeAsSequence(valueElement);
330    }
331    catch (final ASN1Exception ae)
332    {
333      Debug.debugException(ae);
334      throw new LDAPException(ResultCode.DECODING_ERROR,
335                              ERR_PAGED_RESULTS_VALUE_NOT_SEQUENCE.get(ae), ae);
336    }
337
338    final ASN1Element[] valueElements = valueSequence.elements();
339    if (valueElements.length != 2)
340    {
341      throw new LDAPException(ResultCode.DECODING_ERROR,
342                              ERR_PAGED_RESULTS_INVALID_ELEMENT_COUNT.get(
343                                   valueElements.length));
344    }
345
346    try
347    {
348      size = ASN1Integer.decodeAsInteger(valueElements[0]).intValue();
349    }
350    catch (final ASN1Exception ae)
351    {
352      Debug.debugException(ae);
353      throw new LDAPException(ResultCode.DECODING_ERROR,
354                              ERR_PAGED_RESULTS_FIRST_NOT_INTEGER.get(ae), ae);
355    }
356
357    cookie = ASN1OctetString.decodeAsOctetString(valueElements[1]);
358  }
359
360
361
362  /**
363   * {@inheritDoc}
364   */
365  @Override()
366  public SimplePagedResultsControl
367              decodeControl(final String oid, final boolean isCritical,
368                            final ASN1OctetString value)
369         throws LDAPException
370  {
371    return new SimplePagedResultsControl(oid, isCritical, value);
372  }
373
374
375
376  /**
377   * Extracts a simple paged results response control from the provided result.
378   *
379   * @param  result  The result from which to retrieve the simple paged results
380   *                 response control.
381   *
382   * @return  The simple paged results response control contained in the
383   *          provided result, or {@code null} if the result did not contain a
384   *          simple paged results response control.
385   *
386   * @throws  LDAPException  If a problem is encountered while attempting to
387   *                         decode the simple paged results response control
388   *                         contained in the provided result.
389   */
390  public static SimplePagedResultsControl get(final SearchResult result)
391         throws LDAPException
392  {
393    final Control c = result.getResponseControl(PAGED_RESULTS_OID);
394    if (c == null)
395    {
396      return null;
397    }
398
399    if (c instanceof SimplePagedResultsControl)
400    {
401      return (SimplePagedResultsControl) c;
402    }
403    else
404    {
405      return new SimplePagedResultsControl(c.getOID(), c.isCritical(),
406           c.getValue());
407    }
408  }
409
410
411
412  /**
413   * Encodes the provided information into an octet string that can be used as
414   * the value for this control.
415   *
416   * @param  pageSize  The maximum number of entries that the server should
417   *                   return in the next page of the results.
418   * @param  cookie    The cookie provided by the server after returning the
419   *                   previous page of results, or {@code null} if this request
420   *                   will retrieve the first page of results.
421   *
422   * @return  An ASN.1 octet string that can be used as the value for this
423   *          control.
424   */
425  private static ASN1OctetString encodeValue(final int pageSize,
426                                             final ASN1OctetString cookie)
427  {
428    final ASN1Element[] valueElements;
429    if (cookie == null)
430    {
431      valueElements = new ASN1Element[]
432      {
433        new ASN1Integer(pageSize),
434        new ASN1OctetString()
435      };
436    }
437    else
438    {
439      valueElements = new ASN1Element[]
440      {
441        new ASN1Integer(pageSize),
442        cookie
443      };
444    }
445
446    return new ASN1OctetString(new ASN1Sequence(valueElements).encode());
447  }
448
449
450
451  /**
452   * Retrieves the size for this paged results control.  For a request control,
453   * it may be used to specify the number of entries that should be included in
454   * the next page of results.  For a response control, it may be used to
455   * specify the estimated number of entries in the complete result set.
456   *
457   * @return  The size for this paged results control.
458   */
459  public int getSize()
460  {
461    return size;
462  }
463
464
465
466  /**
467   * Retrieves the cookie for this control, which may be used in a subsequent
468   * request to resume reading entries from the next page of results.  The
469   * value should have a length of zero when used to retrieve the first page of
470   * results for a given search, and also in the response from the server when
471   * there are no more entries to send.  It should be non-empty for all other
472   * conditions.
473   *
474   * @return  The cookie for this control, or {@code null} if there is none.
475   */
476  public ASN1OctetString getCookie()
477  {
478    return cookie;
479  }
480
481
482
483  /**
484   * Indicates whether there are more results to return as part of this search.
485   *
486   * @return  {@code true} if there are more results to return, or
487   *          {@code false} if not.
488   */
489  public boolean moreResultsToReturn()
490  {
491    return (cookie.getValue().length > 0);
492  }
493
494
495
496  /**
497   * {@inheritDoc}
498   */
499  @Override()
500  public String getControlName()
501  {
502    return INFO_CONTROL_NAME_PAGED_RESULTS.get();
503  }
504
505
506
507  /**
508   * {@inheritDoc}
509   */
510  @Override()
511  public void toString(final StringBuilder buffer)
512  {
513    buffer.append("SimplePagedResultsControl(pageSize=");
514    buffer.append(size);
515    buffer.append(", isCritical=");
516    buffer.append(isCritical());
517    buffer.append(')');
518  }
519}