001/*
002 * Copyright 2007-2024 Ping Identity Corporation
003 * All Rights Reserved.
004 */
005/*
006 * Copyright 2007-2024 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) 2007-2024 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.asn1;
037
038
039
040import com.unboundid.util.Debug;
041import com.unboundid.util.NotMutable;
042import com.unboundid.util.NotNull;
043import com.unboundid.util.StaticUtils;
044import com.unboundid.util.ThreadSafety;
045import com.unboundid.util.ThreadSafetyLevel;
046
047import static com.unboundid.asn1.ASN1Messages.*;
048
049
050
051/**
052 * This class provides an ASN.1 null element, which does not hold a value.  Null
053 * elements are generally used as placeholders that can be substituted for other
054 * types of elements.
055 */
056@NotMutable()
057@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
058public final class ASN1Null
059       extends ASN1Element
060{
061  /**
062   * A pre-allocated ASN.1 null element with the universal null BER type.
063   */
064  @NotNull public static final ASN1Null UNIVERSAL_NULL_ELEMENT = new ASN1Null();
065
066
067
068  /**
069   * The serial version UID for this serializable class.
070   */
071  private static final long serialVersionUID = -3264450066845549348L;
072
073
074
075  /**
076   * Creates a new ASN.1 null element with the default BER type.
077   */
078  public ASN1Null()
079  {
080    super(ASN1Constants.UNIVERSAL_NULL_TYPE);
081  }
082
083
084
085  /**
086   * Creates a new ASN.1 null element with the specified BER type.
087   *
088   * @param  type  The BER type to use for this ASN.1 null element.
089   */
090  public ASN1Null(final byte type)
091  {
092    super(type);
093  }
094
095
096
097  /**
098   * Decodes the contents of the provided byte array as a null element.
099   *
100   * @param  elementBytes  The byte array to decode as an ASN.1 null element.
101   *
102   * @return  The decoded ASN.1 null element.
103   *
104   * @throws  ASN1Exception  If the provided array cannot be decoded as a null
105   *                         element.
106   */
107  @NotNull()
108  public static ASN1Null decodeAsNull(@NotNull final byte[] elementBytes)
109         throws ASN1Exception
110  {
111    try
112    {
113      int valueStartPos = 2;
114      int length = (elementBytes[1] & 0x7F);
115      if (length != elementBytes[1])
116      {
117        final int numLengthBytes = length;
118
119        length = 0;
120        for (int i=0; i < numLengthBytes; i++)
121        {
122          length <<= 8;
123          length |= (elementBytes[valueStartPos++] & 0xFF);
124        }
125      }
126
127      if ((elementBytes.length - valueStartPos) != length)
128      {
129        throw new ASN1Exception(ERR_ELEMENT_LENGTH_MISMATCH.get(length,
130                                     (elementBytes.length - valueStartPos)));
131      }
132
133      if (length != 0)
134      {
135        throw new ASN1Exception(ERR_NULL_HAS_VALUE.get());
136      }
137
138      return new ASN1Null(elementBytes[0]);
139    }
140    catch (final ASN1Exception ae)
141    {
142      Debug.debugException(ae);
143      throw ae;
144    }
145    catch (final Exception e)
146    {
147      Debug.debugException(e);
148      throw new ASN1Exception(ERR_ELEMENT_DECODE_EXCEPTION.get(e), e);
149    }
150  }
151
152
153
154  /**
155   * Decodes the provided ASN.1 element as a null element.
156   *
157   * @param  element  The ASN.1 element to be decoded.
158   *
159   * @return  The decoded ASN.1 null element.
160   *
161   * @throws  ASN1Exception  If the provided element cannot be decoded as a null
162   *                         element.
163   */
164  @NotNull()
165  public static ASN1Null decodeAsNull(@NotNull final ASN1Element element)
166         throws ASN1Exception
167  {
168    if (element.getValue().length != 0)
169    {
170      throw new ASN1Exception(ERR_NULL_HAS_VALUE.get());
171    }
172
173    return new ASN1Null(element.getType());
174  }
175
176
177
178  /**
179   * {@inheritDoc}
180   */
181  @Override()
182  public void toString(@NotNull final StringBuilder buffer)
183  {
184    buffer.append("ASN1Null(type=");
185    StaticUtils.toHex(getType(), buffer);
186    buffer.append(')');
187  }
188}