com.novell.ldap.asn1.ASN1Identifier Maven / Gradle / Ivy
/* **************************************************************************
* $OpenLDAP$
*
* Copyright (C) 1999, 2000, 2001 Novell, Inc. All Rights Reserved.
*
* THIS WORK IS SUBJECT TO U.S. AND INTERNATIONAL COPYRIGHT LAWS AND
* TREATIES. USE, MODIFICATION, AND REDISTRIBUTION OF THIS WORK IS SUBJECT
* TO VERSION 2.0.1 OF THE OPENLDAP PUBLIC LICENSE, A COPY OF WHICH IS
* AVAILABLE AT HTTP://WWW.OPENLDAP.ORG/LICENSE.HTML OR IN THE FILE "LICENSE"
* IN THE TOP-LEVEL DIRECTORY OF THE DISTRIBUTION. ANY USE OR EXPLOITATION
* OF THIS WORK OTHER THAN AS AUTHORIZED IN VERSION 2.0.1 OF THE OPENLDAP
* PUBLIC LICENSE, OR OTHER PRIOR WRITTEN CONSENT FROM NOVELL, COULD SUBJECT
* THE PERPETRATOR TO CRIMINAL AND CIVIL LIABILITY.
******************************************************************************/
package com.novell.ldap.asn1;
import java.io.IOException;
import java.io.InputStream;
import java.io.EOFException;
/**
* This class is used to encapsulate an ASN.1 Identifier.
*
* An ASN1Identifier is composed of three parts:
*
a class type,
* a form, and
* a tag.
*
* The class type is defined as:
*
* bit 8 7 TAG CLASS
* ------- -----------
* 0 0 UNIVERSAL
* 0 1 APPLICATION
* 1 0 CONTEXT
* 1 1 PRIVATE
*
* The form is defined as:
*
* bit 6 FORM
* ----- --------
* 0 PRIMITIVE
* 1 CONSTRUCTED
*
*
* Note: CONSTRUCTED types are made up of other CONSTRUCTED or PRIMITIVE
* types.
*
* The tag is defined as:
*
* bit 5 4 3 2 1 TAG
* ------------- ---------------------------------------------
* 0 0 0 0 0
* . . . . .
* 1 1 1 1 0 (0-30) single octet tag
*
* 1 1 1 1 1 (> 30) multiple octet tag, more octets follow
*
*/
public class ASN1Identifier extends Object implements Cloneable,
java.io.Serializable {
/**
* Universal tag class.
*
* UNIVERSAL = 0
*/
public static final int UNIVERSAL = 0;
/**
* Application-wide tag class.
*
* APPLICATION = 1
*/
public static final int APPLICATION = 1;
/**
* Context-specific tag class.
*
* CONTEXT = 2
*/
public static final int CONTEXT = 2;
/**
* Private-use tag class.
*
* PRIVATE = 3
*/
public static final int PRIVATE = 3;
/* Private variables
*/
private int tagClass;
private boolean constructed;
private int tag;
private int encodedLength;
/* Constructors for ASN1Identifier
*/
/**
* Constructs an ASN1Identifier using the classtype, form and tag.
*
* @param tagClass As defined above.
*
* @param constructed Set to true if constructed and false if primitive.
*
* @param tag The tag of this identifier
*/
public ASN1Identifier(int tagClass, boolean constructed, int tag)
{
this.tagClass = tagClass;
this.constructed = constructed;
this.tag = tag;
}
/**
* Decode an ASN1Identifier directly from an InputStream and
* save the encoded length of the ASN1Identifier.
*
* @param in The input stream to decode from.
*/
public ASN1Identifier(InputStream in)
throws IOException
{
int r = in.read();
encodedLength++;
if(r < 0)
throw new EOFException("BERDecoder: decode: EOF in Identifier");
tagClass = r >> 6;
constructed = (r & 0x20) != 0;
tag = r & 0x1F; // if tag < 30 then its a single octet identifier.
if(tag == 0x1F) // if true, its a multiple octet identifier.
tag = decodeTagNumber(in);
return;
}
public ASN1Identifier()
{
return;
}
/**
* Decode an ASN1Identifier directly from an InputStream and
* save the encoded length of the ASN1Identifier, but reuse the object.
*
* @param in The input stream to decode from.
*/
public final void reset(InputStream in)
throws IOException
{
encodedLength = 0;
int r = in.read();
encodedLength++;
if(r < 0)
throw new EOFException("BERDecoder: decode: EOF in Identifier");
tagClass = r >> 6;
constructed = (r & 0x20) != 0;
tag = r & 0x1F; // if tag < 30 then its a single octet identifier.
if(tag == 0x1F) // if true, its a multiple octet identifier.
tag = decodeTagNumber(in);
}
/**
* In the case that we have a tag number that is greater than 30, we need
* to decode a multiple octet tag number.
*/
private int decodeTagNumber(InputStream in)
throws IOException
{
int n = 0;
while(true) {
int r = in.read();
encodedLength++;
if(r < 0)
throw new EOFException("BERDecoder: decode: EOF in tag number");
n = (n<<7) + (r & 0x7F);
if((r & 0x80) == 0)
break;
}
return n;
}
/**
* Returns the CLASS of this ASN1Identifier as an int value.
*
* @see #UNIVERSAL
* @see #APPLICATION
* @see #CONTEXT
* @see #PRIVATE
*/
public final int getASN1Class()
{
return tagClass;
}
/**
* Return a boolean indicating if the constructed bit is set.
*
* @return true if constructed and false if primitive.
*/
public final boolean getConstructed()
{
return constructed;
}
/**
* Returns the TAG of this ASN1Identifier.
*/
public final int getTag()
{
return tag;
}
/**
* Returns the encoded length of this ASN1Identifier.
*/
public final int getEncodedLength()
{
return encodedLength;
}
/* Convenience methods
*/
/**
* Returns a boolean value indicating whether or not this ASN1Identifier
* has a TAG CLASS of UNIVERSAL.
*
* @see #UNIVERSAL
*/
public final boolean isUniversal()
{
return tagClass == UNIVERSAL;
}
/**
* Returns a boolean value indicating whether or not this ASN1Identifier
* has a TAG CLASS of APPLICATION.
*
* @see #APPLICATION
*/
public final boolean isApplication()
{
return tagClass == APPLICATION;
}
/**
* Returns a boolean value indicating whether or not this ASN1Identifier
* has a TAG CLASS of CONTEXT-SPECIFIC.
*
* @see #CONTEXT
*/
public final boolean isContext()
{
return tagClass == CONTEXT;
}
/**
* Returns a boolean value indicating whether or not this ASN1Identifier
* has a TAG CLASS of PRIVATE.
*
* @see #PRIVATE
*/
public final boolean isPrivate()
{
return tagClass == PRIVATE;
}
/**
* Creates a duplicate, not a true clone, of this object and returns
* a reference to the duplicate.
*
*/
public Object clone()
{
try {
return super.clone();
} catch( CloneNotSupportedException ce) {
throw new RuntimeException("Internal error, cannot create clone");
}
}
/**
* Writes the object state to a stream in standard Default Binary format
* This function wraps ObjectOutputStream' s defaultWriteObject() to write
* the non-static and non-transient fields of the current class to the stream
*
* @param objectOStrm The OutputSteam where the Object need to be written
*/
private void writeObject(java.io.ObjectOutputStream objectOStrm)
throws java.io.IOException {
objectOStrm.defaultWriteObject();
}
/**
* Reads the serialized object from the underlying input stream.
* This function wraps ObjectInputStream's defaultReadObject() function
*
* @param objectIStrm InputStream used to recover those objects previously serialized.
*/
private void readObject(java.io.ObjectInputStream objectIStrm)
throws java.io.IOException, ClassNotFoundException
{
objectIStrm.defaultReadObject();
}
}