📄 tag.java
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/* $Id: Tag.java,v 1.2 2001/05/24 19:25:52 raif Exp $
*
* Copyright (C) 1997-2001 The Cryptix Foundation Limited. All rights reserved.
*
* Use, modification, copying and distribution of this software is subject to
* the terms and conditions of the Cryptix General Licence. You should have
* received a copy of the Cryptix General Licence along with this library; if
* not, you can download a copy from http://www.cryptix.org/
*/
package cryptix.asn1.lang;
import java.io.Serializable;
/**
* The representation of an ASN.1 Tag.<p>
*
* @version $Revision: 1.2 $
* @author Raif S. Naffah
*/
public class Tag implements Serializable {
// Constants and variables
// .......................................................................
/**
* Constant values for Tag classes.
*/
public static final int UNIVERSAL = 0x00;
public static final int APPLICATION = 0x40;
public static final int CONTEXT = 0x80;
public static final int PRIVATE = 0xC0;
/**
* Constant values for Tag values.
*/
public static final int BOOLEAN = 0x01;
public static final int INTEGER = 0x02;
public static final int BIT_STRING = 0x03;
public static final int OCTET_STRING = 0x04;
public static final int NULL = 0x05;
public static final int OBJECT_IDENTIFIER = 0x06;
public static final int REAL = 0x09;
public static final int SEQUENCE = 0x10; // 16
public static final int SEQUENCE_OF = 0x10;
public static final int SET = 0x11; // 17
public static final int SET_OF = 0x11;
public static final int NUMERIC_STRING = 0x12; // 18
public static final int PRINTABLE_STRING = 0x13; // 19
public static final int T61_STRING = 0x14; // 20
public static final int VIDEOTEX_STRING = 0x15; // 21
public static final int IA5_STRING = 0x16; // 22
public static final int GRAPHIC_STRING = 0x19; // 25
public static final int ISO646_STRING = 0x1A; // 26
public static final int GENERAL_STRING = 0x1B; // 27
public static final int UNIVERSAL_STRING = 0x1C; // 28
public static final int BMP_STRING = 0x1E; // 30
public static final int UTC_TIME = 0x17; // 23
public static final int GENERALIZED_TIME = 0x18; // 24
int clazz; // the tag's class id
int value; // the tag's actual value
boolean explicit; // is it explicit or implicit?
boolean constructed; // is it constructed?
// Constructor(s)
// .......................................................................
/**
* Constructs an ASN.1 Tag instance.
*
* @param clazz the tag's class.
* @param value the tag's value.
* @param explicit whether this tag is explicit or implicit. Default is
* explicit.
* @param constructed Whether this tag is constructed or not. Default is not
* constrcuted.
*/
public Tag(int clazz, int value, boolean explicit, boolean constructed) {
super();
this.clazz = clazz;
this.value = value;
this.explicit = explicit;
this.constructed = constructed;
}
/**
* Convenience constructor. Constructs an ASN.1 Tag instance. The resulting
* tag is of a non-constructed type.
*
* @param clazz the tag's class.
* @param value the tag's value.
* @param explicit whether this tag is explicit or implicit. Default is
* explicit.
*/
public Tag(int clazz, int value, boolean explicit) {
this(clazz, value, explicit, false);
}
/**
* Convenience constructor. Constructs an ASN.1 Tag instance. The resulting
* tag is explicit, of a non-constructed type.
*
* @param clazz the tag's class.
* @param value the tag's value.
*/
public Tag(int clazz, int value) {
this(clazz, value, true, false);
}
/**
* Convenience constructor. Constructs an ASN.1 Tag instance. The resulting
* tag is of class UNIVERSAL and is of a non-constructed type.
*
* @param value the tag's value.
* @param explicit whether this tag is explicit or implicit. Default is
* explicit.
*/
public Tag(int value, boolean explicit) {
this(Tag.UNIVERSAL, value, explicit, false);
}
/**
* Convenience constructor. Constructs an ASN.1 Tag instance. The resulting
* tag is of class UNIVERSAL, is explicit, and is of a non-constructed type.
*
* @param value the tag's value.
*/
public Tag(int value) {
this(Tag.UNIVERSAL, value, true, false);
}
/**
* Private constructor for cloning purposes.
*
* @param that the tag to clone.
*/
private Tag(Tag that) {
this(that.clazz, that.value, that.explicit, that.constructed);
}
// Cloneable interface methods
// .......................................................................
/**
* Returns a cloned instance of this.
*
* @return a cloned instance of this.
*/
public Object clone() {
return new Tag(this);
}
// java.lang.Object overloaded methods
// .......................................................................
/**
* Tests for equality between this instance and a designated object.
*
* @param obj a designated object to test for equality with this instance.
* @return true if the designated object is an instance of Tag, and has the
* same class and value as this one.
*/
public boolean equals(Object obj) {
if (!(obj instanceof Tag))
return false;
Tag that = (Tag) obj;
if (this.getClazz() != that.getClazz())
return false;
return (this.getValue() == that.getValue());
}
// Accessor methods
// .......................................................................
/**
* Returns the tag's class.
*
* @return the tag's class.
*/
public int getClazz() {
return clazz;
}
/**
* Returns the tag's class number.
*
* @return the tag's class number.
*/
public int getValue() {
return value;
}
/**
* Returns true if the tag is explicit, false otherwise.
*
* @return true if the tag is explicit, false otherwise.
*/
public boolean isExplicit() {
return explicit;
}
/**
* Returns true if the tag is constructed false otherwise.
*
* @return true if the tag is constructed false otherwise.
*/
public boolean isConstructed() {
return constructed;
}
/**
* Convenience method. Returns true if this tag is UNIVERSAL.
*
* @return true if this tag's class is UNIVERSAL; false otherwise.
*/
public boolean isUniversal() {
return (clazz == Tag.UNIVERSAL);
}
// Visualisation methods
// .......................................................................
/**
* Returns a string representation of this instance.
*
* @return a string representation of this instance.
*/
public String toString() {
StringBuffer result = new StringBuffer("<Tag class=\"");
switch (clazz) {
case UNIVERSAL: result.append("UNIVERSAL"); break;
case APPLICATION: result.append("APPLICATION"); break;
case CONTEXT: result.append("CONTEXT"); break;
case PRIVATE: result.append("PRIVATE"); break;
default: result.append(clazz);
}
result.append("\" value=\"");
if (clazz == CONTEXT)
result.append(value);
else
switch (value) {
case BOOLEAN: result.append("BOOLEAN"); break;
case INTEGER: result.append("INTEGER"); break;
case BIT_STRING: result.append("BIT STRING"); break;
case OCTET_STRING: result.append("OCTET STRING"); break;
case NULL: result.append("NULL"); break;
case OBJECT_IDENTIFIER: result.append("OBJECT IDENTIFIER"); break;
case SEQUENCE: result.append("SEQUENCE [OF]"); break;
case SET: result.append("SET [OF]"); break;
case NUMERIC_STRING: result.append("NumericString"); break;
case PRINTABLE_STRING: result.append("PrintableString"); break;
case T61_STRING: result.append("TeletexString"); break;
case VIDEOTEX_STRING: result.append("VideotexString"); break;
case IA5_STRING: result.append("IA5String"); break;
case GRAPHIC_STRING: result.append("GraphicString"); break;
case ISO646_STRING: result.append("VisibleString"); break;
case GENERAL_STRING: result.append("GeneralString"); break;
case UNIVERSAL_STRING: result.append("UniversalString"); break;
case BMP_STRING: result.append("BMPString"); break;
case UTC_TIME: result.append("UTCTime"); break;
case GENERALIZED_TIME: result.append("GeneralizedTime"); break;
default: result.append(value);
}
result.append("\" explicit=\"").append(String.valueOf(explicit));
result.append("\" constructed=\"").append(String.valueOf(constructed)).append("\" />");
return result.toString();
}
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