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