/*
* Copyright 2007-2013 UnboundID Corp.
* All Rights Reserved.
*/
/*
* Copyright (C) 2008-2013 UnboundID Corp.
*
* 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 <http://www.gnu.org/licenses>.
*/
package com.hwlcn.ldap.asn1;
import com.hwlcn.ldap.util.ByteString;
import com.hwlcn.ldap.util.ByteStringBuffer;
import com.hwlcn.core.annotation.NotMutable;
import com.hwlcn.core.annotation.ThreadSafety;
import com.hwlcn.ldap.util.ThreadSafetyLevel;
import static com.hwlcn.ldap.asn1.ASN1Constants.*;
import static com.hwlcn.ldap.asn1.ASN1Messages.*;
import static com.hwlcn.ldap.util.Debug.*;
import static com.hwlcn.ldap.util.StaticUtils.*;
import static com.hwlcn.ldap.util.Validator.*;
/**
* This class provides an ASN.1 octet string element, whose value is simply
* comprised of zero or more bytes. Octet string elements are frequently used
* to represent string values as well.
*/
@NotMutable()
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class ASN1OctetString
extends ASN1Element
implements ByteString
{
/**
* The serial version UID for this serializable class.
*/
private static final long serialVersionUID = -7857753188341295516L;
/*
* NOTE: This class uses lazy initialization for the value. The value may
* be initially specified as either a string or a byte array, and if the value
* is provided as a string, then the byte array version of that value will be
* computed on-demand later. 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. This is only needed for the valueBytes
* array because it is not required for primitives (like length and offset) or
* for objects with only final fields (like stringValue).
*
* In the majority of cases, passing the value 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 binary representation of the value for this element.
private byte[] valueBytes;
// A volatile variable used to guard publishing the valueBytes array. See the
// note above to explain why this is needed.
private volatile byte[] valueBytesGuard;
// The length of the value in the byte array, if applicable.
private int length;
// The offset in the byte array at which the value begins, if applicable.
private int offset;
// The string representation of the value for this element.
private String stringValue;
/**
* Creates a new ASN.1 octet string element with the default BER type and
* no value.
*/
public ASN1OctetString()
{
super(UNIVERSAL_OCTET_STRING_TYPE);
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
/**
* Creates a new ASN.1 octet string element with the specified type and no
* value.
*
* @param type The BER type to use for this element.
*/
public ASN1OctetString(final byte type)
{
super(type);
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
/**
* Creates a new ASN.1 octet string element with the default BER type and the
* provided value.
*
* @param value The value to use for this element.
*/
public ASN1OctetString(final byte[] value)
{
super(UNIVERSAL_OCTET_STRING_TYPE);
if (value == null)
{
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
else
{
valueBytes = value;
stringValue = null;
offset = 0;
length = value.length;
}
}
/**
* Creates a new ASN.1 octet string element with the default BER type and the
* provided value.
*
* @param value The byte array containing the value to use for this
* element It must not be {@code null}.
* @param offset The offset within the array at which the value begins. It
* must be greater than or equal to zero and less than or
* equal to the length of the array.
* @param length The length in bytes of the value. It must be greater than
* or equal to zero, and it must not extend beyond the end of
* the array.
*/
public ASN1OctetString(final byte[] value, final int offset, final int length)
{
super(UNIVERSAL_OCTET_STRING_TYPE);
ensureNotNull(value);
ensureTrue((offset >= 0) && (length >= 0) &&
(offset+length <= value.length));
valueBytes = value;
stringValue = null;
this.offset = offset;
this.length = length;
}
/**
* Creates a new ASN.1 octet string element with the specified type and the
* provided value.
*
* @param type The BER type to use for this element.
* @param value The value to use for this element.
*/
public ASN1OctetString(final byte type, final byte[] value)
{
super(type);
if (value == null)
{
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
else
{
valueBytes = value;
stringValue = null;
offset = 0;
length = value.length;
}
}
/**
* Creates a new ASN.1 octet string element with the specified type and the
* provided value.
*
* @param type The BER type to use for this element.
* @param value The byte array containing the value to use for this
* element. It must not be {@code null}.
* @param offset The offset within the array at which the value begins. It
* must be greater than or equal to zero and less than or
* equal to the length of the array..
* @param length The length in bytes of the value. It must be greater than
* or equal to zero, and it must not extend beyond the end of
* the array.
*/
public ASN1OctetString(final byte type, final byte[] value, final int offset,
final int length)
{
super(type);
ensureTrue((offset >= 0) && (length >= 0) &&
(offset+length <= value.length));
valueBytes = value;
stringValue = null;
this.offset = offset;
this.length = length;
}
/**
* Creates a new ASN.1 octet string element with the default BER type and the
* provided value.
*
* @param value The value to use for this element.
*/
public ASN1OctetString(final String value)
{
super(UNIVERSAL_OCTET_STRING_TYPE);
if (value == null)
{
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
else
{
valueBytes = null;
stringValue = value;
offset = -1;
length = -1;
}
}
/**
* Creates a new ASN.1 octet string element with the specified type and the
* provided value.
*
* @param type The BER type to use for this element.
* @param value The value to use for this element.
*/
public ASN1OctetString(final byte type, final String value)
{
super(type);
if (value == null)
{
valueBytes = NO_BYTES;
stringValue = "";
offset = 0;
length = 0;
}
else
{
valueBytes = null;
stringValue = value;
offset = -1;
length = -1;
}
}
/**
* {@inheritDoc}
*/
@Override()
byte[] getValueArray()
{
return getValue();
}
/**
* {@inheritDoc}
*/
@Override()
int getValueOffset()
{
return 0;
}
/**
* {@inheritDoc}
*/
@Override()
public int getValueLength()
{
return getValue().length;
}
/**
* {@inheritDoc}
*/
@Override()
public byte[] getValue()
{
if (valueBytes == null)
{
valueBytesGuard = getBytes(stringValue);
offset = 0;
length = valueBytesGuard.length;
valueBytes = valueBytesGuard;
}
else if ((offset != 0) || (length != valueBytes.length))
{
final byte[] newArray = new byte[length];
System.arraycopy(valueBytes, offset, newArray, 0, length);
offset = 0;
valueBytesGuard = newArray;
valueBytes = valueBytesGuard;
}
return valueBytes;
}
/**
* {@inheritDoc}
*/
@Override()
public void encodeTo(final ByteStringBuffer buffer)
{
buffer.append(getType());
if (valueBytes == null)
{
// Assume that the string contains only ASCII characters. That will be
// true most of the time and we can optimize for it. If it's not true,
// then we'll fix it later.
final int stringLength = stringValue.length();
final int lengthStartPos = buffer.length();
encodeLengthTo(stringLength, buffer);
final int valueStartPos = buffer.length();
buffer.append(stringValue);
final int stringBytesLength = buffer.length() - valueStartPos;
if (stringBytesLength != stringLength)
{
// This must mean that the string had non-ASCII characters in it, so
// fix the encoded representation.
final byte[] newLengthBytes = encodeLength(stringBytesLength);
if (newLengthBytes.length == (valueStartPos - lengthStartPos))
{
// It takes the same number of bytes to encode the new length as
// the length we previously expected, so we can just overwrite the
// length bytes in the backing array.
System.arraycopy(newLengthBytes, 0, buffer.getBackingArray(),
lengthStartPos, newLengthBytes.length);
}
else
{
buffer.setLength(lengthStartPos);
buffer.append(newLengthBytes);
buffer.append(stringValue);
}
}
}
else
{
encodeLengthTo(length, buffer);
buffer.append(valueBytes, offset, length);
}
}
/**
* Retrieves the string value for this element.
*
* @return The String value for this element.
*/
public String stringValue()
{
if (stringValue == null)
{
if (length == 0)
{
stringValue = "";
}
else
{
stringValue = toUTF8String(valueBytes, offset, length);
}
}
return stringValue;
}
/**
* Decodes the contents of the provided byte array as an octet string element.
*
* @param elementBytes The byte array to decode as an ASN.1 octet string
* element.
*
* @return The decoded ASN.1 octet string element.
*
* @throws com.hwlcn.ldap.asn1.ASN1Exception If the provided array cannot be decoded as an
* octet string element.
*/
public static ASN1OctetString decodeAsOctetString(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)));
}
return new ASN1OctetString(elementBytes[0], elementBytes, valueStartPos,
length);
}
catch (final ASN1Exception ae)
{
debugException(ae);
throw ae;
}
catch (final Exception e)
{
debugException(e);
throw new ASN1Exception(ERR_ELEMENT_DECODE_EXCEPTION.get(e), e);
}
}
/**
* Decodes the provided ASN.1 element as an octet string element.
*
* @param element The ASN.1 element to be decoded.
*
* @return The decoded ASN.1 octet string element.
*/
public static ASN1OctetString decodeAsOctetString(final ASN1Element element)
{
return new ASN1OctetString(element.getType(), element.getValue());
}
/**
* Appends the value of this ASN.1 octet string to the provided buffer.
*
* @param buffer The buffer to which the value is to be appended.
*/
public void appendValueTo(final ByteStringBuffer buffer)
{
if (valueBytes == null)
{
buffer.append(stringValue);
}
else
{
buffer.append(valueBytes, offset, length);
}
}
/**
* Converts this byte string to an ASN.1 octet string.
*
* @return An ASN.1 octet string with the value of this byte string.
*/
public ASN1OctetString toASN1OctetString()
{
return this;
}
/**
* Appends a string representation of this ASN.1 element to the provided
* buffer.
*
* @param buffer The buffer to which to append the information.
*/
@Override()
public void toString(final StringBuilder buffer)
{
buffer.append(stringValue());
}
}