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The UnboundID LDAP SDK for Java is a fast, comprehensive, and easy-to-use
Java API for communicating with LDAP directory servers and performing
related tasks like reading and writing LDIF, encoding and decoding data
using base64 and ASN.1 BER, and performing secure communication. This
package contains the Standard Edition of the LDAP SDK, which is a
complete, general-purpose library for communicating with LDAPv3 directory
servers.
/*
* Copyright 2007-2023 Ping Identity Corporation
* All Rights Reserved.
*/
/*
* Copyright 2007-2023 Ping Identity Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Copyright (C) 2007-2023 Ping Identity Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (GPLv2 only)
* or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
* as published by the Free Software Foundation.
*
* This program 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
*/
package com.unboundid.asn1;
import java.util.ArrayList;
import java.util.Collection;
import com.unboundid.util.ByteStringBuffer;
import com.unboundid.util.Debug;
import com.unboundid.util.NotMutable;
import com.unboundid.util.NotNull;
import com.unboundid.util.Nullable;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import static com.unboundid.asn1.ASN1Messages.*;
/**
* This class provides an ASN.1 sequence element, which is used to hold an
* ordered set of zero or more other elements (potentially including additional
* "envelope" element types like other sequences and/or sets).
*/
@NotMutable()
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class ASN1Sequence
extends ASN1Element
{
/**
* The serial version UID for this serializable class.
*/
private static final long serialVersionUID = 7294248008273774906L;
/*
* NOTE: This class uses lazy initialization for the encoded value. The
* encoded value should only be needed by the getValue() method, which is used
* by ASN1Element.encode(). Even though this class is externally immutable,
* that does not by itself make it completely threadsafe, because weirdness in
* the Java memory model could allow the assignment to be performed out of
* order. By passing the value through a volatile variable any time the value
* is set other than in the constructor (which will always be safe) we ensure
* that this reordering cannot happen.
*
* In the majority of cases, passing the value through assignments to
* valueBytes through a volatile variable is much faster than declaring
* valueBytes itself to be volatile because a volatile variable cannot be held
* in CPU caches or registers and must only be accessed from memory visible to
* all threads. Since the value may be read much more often than it is
* written, passing it through a volatile variable rather than making it
* volatile directly can help avoid that penalty when possible.
*/
// The set of ASN.1 elements contained in this sequence.
@NotNull private final ASN1Element[] elements;
// The encoded representation of the value, if available.
@Nullable private byte[] encodedValue;
// A volatile variable used to guard publishing the encodedValue array. See
// the note above to explain why this is needed.
@Nullable
private volatile byte[] encodedValueGuard;
/**
* Creates a new ASN.1 sequence with the default BER type and no encapsulated
* elements.
*/
public ASN1Sequence()
{
super(ASN1Constants.UNIVERSAL_SEQUENCE_TYPE);
elements = ASN1Constants.NO_ELEMENTS;
encodedValue = ASN1Constants.NO_VALUE;
}
/**
* Creates a new ASN.1 sequence with the specified BER type and no
* encapsulated elements.
*
* @param type The BER type to use for this element.
*/
public ASN1Sequence(final byte type)
{
super(type);
elements = ASN1Constants.NO_ELEMENTS;
encodedValue = ASN1Constants.NO_VALUE;
}
/**
* Creates a new ASN.1 sequence with the default BER type and the provided set
* of elements.
*
* @param elements The set of elements to include in this sequence.
*/
public ASN1Sequence(@Nullable final ASN1Element... elements)
{
super(ASN1Constants.UNIVERSAL_SEQUENCE_TYPE);
if (elements == null)
{
this.elements = ASN1Constants.NO_ELEMENTS;
}
else
{
this.elements = elements;
}
encodedValue = null;
}
/**
* Creates a new ASN.1 sequence with the default BER type and the provided set
* of elements.
*
* @param elements The set of elements to include in this sequence.
*/
public ASN1Sequence(
@Nullable final Collection elements)
{
super(ASN1Constants.UNIVERSAL_SEQUENCE_TYPE);
if ((elements == null) || elements.isEmpty())
{
this.elements = ASN1Constants.NO_ELEMENTS;
}
else
{
this.elements = new ASN1Element[elements.size()];
elements.toArray(this.elements);
}
encodedValue = null;
}
/**
* Creates a new ASN.1 sequence with the specified BER type and the provided
* set of elements.
*
* @param type The BER type to use for this element.
* @param elements The set of elements to include in this sequence.
*/
public ASN1Sequence(final byte type,
@Nullable final ASN1Element... elements)
{
super(type);
if (elements == null)
{
this.elements = ASN1Constants.NO_ELEMENTS;
}
else
{
this.elements = elements;
}
encodedValue = null;
}
/**
* Creates a new ASN.1 sequence with the specified BER type and the provided
* set of elements.
*
* @param type The BER type to use for this element.
* @param elements The set of elements to include in this sequence.
*/
public ASN1Sequence(final byte type,
@Nullable final Collection elements)
{
super(type);
if ((elements == null) || elements.isEmpty())
{
this.elements = ASN1Constants.NO_ELEMENTS;
}
else
{
this.elements = new ASN1Element[elements.size()];
elements.toArray(this.elements);
}
encodedValue = null;
}
/**
* Creates a new ASN.1 sequence with the specified type, set of elements, and
* encoded value.
*
* @param type The BER type to use for this element.
* @param elements The set of elements to include in this sequence.
* @param value The pre-encoded value for this element.
*/
private ASN1Sequence(final byte type,
@NotNull final ASN1Element[] elements,
@NotNull final byte[] value)
{
super(type);
this.elements = elements;
encodedValue = value;
}
/**
* {@inheritDoc}
*/
@Override()
@NotNull()
byte[] getValueArray()
{
return getValue();
}
/**
* {@inheritDoc}
*/
@Override()
int getValueOffset()
{
return 0;
}
/**
* {@inheritDoc}
*/
@Override()
public int getValueLength()
{
return getValue().length;
}
/**
* {@inheritDoc}
*/
@Override()
@NotNull()
public byte[] getValue()
{
if (encodedValue == null)
{
encodedValueGuard = encodeElements(elements);
encodedValue = encodedValueGuard;
}
return encodedValue;
}
/**
* {@inheritDoc}
*/
@Override()
public void encodeTo(@NotNull final ByteStringBuffer buffer)
{
buffer.append(getType());
if (elements.length == 0)
{
buffer.append((byte) 0x00);
return;
}
// In this case, it will likely be faster to just go ahead and append
// encoded representations of all of the elements and insert the length
// later once we know it.
final int originalLength = buffer.length();
for (final ASN1Element e : elements)
{
e.encodeTo(buffer);
}
buffer.insert(originalLength,
encodeLength(buffer.length() - originalLength));
}
/**
* Encodes the provided set of elements to a byte array suitable for use as
* the element value.
*
* @param elements The set of elements to be encoded.
*
* @return A byte array containing the encoded elements.
*/
@NotNull()
static byte[] encodeElements(@Nullable final ASN1Element[] elements)
{
if ((elements == null) || (elements.length == 0))
{
return ASN1Constants.NO_VALUE;
}
int totalLength = 0;
final int numElements = elements.length;
final byte[][] encodedElements = new byte[numElements][];
for (int i=0; i < numElements; i++)
{
encodedElements[i] = elements[i].encode();
totalLength += encodedElements[i].length;
}
int pos = 0;
final byte[] b = new byte[totalLength];
for (int i=0; i < numElements; i++)
{
System.arraycopy(encodedElements[i], 0, b, pos,
encodedElements[i].length);
pos += encodedElements[i].length;
}
return b;
}
/**
* Retrieves the set of encapsulated elements held in this sequence.
*
* @return The set of encapsulated elements held in this sequence.
*/
@NotNull()
public ASN1Element[] elements()
{
return elements;
}
/**
* Decodes the contents of the provided byte array as a sequence element.
*
* @param elementBytes The byte array to decode as an ASN.1 sequence
* element.
*
* @return The decoded ASN.1 sequence element.
*
* @throws ASN1Exception If the provided array cannot be decoded as a
* sequence element.
*/
@NotNull()
public static ASN1Sequence decodeAsSequence(
@NotNull final byte[] elementBytes)
throws ASN1Exception
{
try
{
int valueStartPos = 2;
int length = (elementBytes[1] & 0x7F);
if (length != elementBytes[1])
{
final int numLengthBytes = length;
length = 0;
for (int i=0; i < numLengthBytes; i++)
{
length <<= 8;
length |= (elementBytes[valueStartPos++] & 0xFF);
}
}
if ((elementBytes.length - valueStartPos) != length)
{
throw new ASN1Exception(ERR_ELEMENT_LENGTH_MISMATCH.get(length,
(elementBytes.length - valueStartPos)));
}
final byte[] value = new byte[length];
System.arraycopy(elementBytes, valueStartPos, value, 0, length);
int numElements = 0;
final ArrayList elementList = new ArrayList<>(5);
try
{
int pos = 0;
while (pos < value.length)
{
final byte type = value[pos++];
final byte firstLengthByte = value[pos++];
int l = (firstLengthByte & 0x7F);
if (l != firstLengthByte)
{
final int numLengthBytes = l;
l = 0;
for (int i=0; i < numLengthBytes; i++)
{
l <<= 8;
l |= (value[pos++] & 0xFF);
}
}
final int posPlusLength = pos + l;
if ((l < 0) || (posPlusLength < 0) || (posPlusLength > value.length))
{
throw new ASN1Exception(
ERR_SEQUENCE_BYTES_DECODE_LENGTH_EXCEEDS_AVAILABLE.get());
}
elementList.add(new ASN1Element(type, value, pos, l));
pos += l;
numElements++;
}
}
catch (final ASN1Exception ae)
{
throw ae;
}
catch (final Exception e)
{
Debug.debugException(e);
throw new ASN1Exception(ERR_SEQUENCE_BYTES_DECODE_EXCEPTION.get(e), e);
}
int i = 0;
final ASN1Element[] elements = new ASN1Element[numElements];
for (final ASN1Element e : elementList)
{
elements[i++] = e;
}
return new ASN1Sequence(elementBytes[0], elements, value);
}
catch (final ASN1Exception ae)
{
Debug.debugException(ae);
throw ae;
}
catch (final Exception e)
{
Debug.debugException(e);
throw new ASN1Exception(ERR_ELEMENT_DECODE_EXCEPTION.get(e), e);
}
}
/**
* Decodes the provided ASN.1 element as a sequence element.
*
* @param element The ASN.1 element to be decoded.
*
* @return The decoded ASN.1 sequence element.
*
* @throws ASN1Exception If the provided element cannot be decoded as a
* sequence element.
*/
@NotNull()
public static ASN1Sequence decodeAsSequence(
@NotNull final ASN1Element element)
throws ASN1Exception
{
int numElements = 0;
final ArrayList elementList = new ArrayList<>(5);
final byte[] value = element.getValue();
try
{
int pos = 0;
while (pos < value.length)
{
final byte type = value[pos++];
final byte firstLengthByte = value[pos++];
int length = (firstLengthByte & 0x7F);
if (length != firstLengthByte)
{
final int numLengthBytes = length;
length = 0;
for (int i=0; i < numLengthBytes; i++)
{
length <<= 8;
length |= (value[pos++] & 0xFF);
}
}
final int posPlusLength = pos + length;
if ((length < 0) || (posPlusLength < 0) ||
(posPlusLength > value.length))
{
throw new ASN1Exception(
ERR_SEQUENCE_DECODE_LENGTH_EXCEEDS_AVAILABLE.get(
String.valueOf(element)));
}
elementList.add(new ASN1Element(type, value, pos, length));
pos += length;
numElements++;
}
}
catch (final ASN1Exception ae)
{
throw ae;
}
catch (final Exception e)
{
Debug.debugException(e);
throw new ASN1Exception(
ERR_SEQUENCE_DECODE_EXCEPTION.get(String.valueOf(element), e), e);
}
int i = 0;
final ASN1Element[] elements = new ASN1Element[numElements];
for (final ASN1Element e : elementList)
{
elements[i++] = e;
}
return new ASN1Sequence(element.getType(), elements, value);
}
/**
* {@inheritDoc}
*/
@Override()
public void toString(@NotNull final StringBuilder buffer)
{
buffer.append('[');
for (int i=0; i < elements.length; i++)
{
if (i > 0)
{
buffer.append(',');
}
elements[i].toString(buffer);
}
buffer.append(']');
}
}