de.intarsys.tools.tlv.common.TlvElement Maven / Gradle / Ivy
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package de.intarsys.tools.tlv.common;
import de.intarsys.tools.hex.HexTools;
/**
* A TLV element is a "tag, length, value" data structure. First, an identifier
* is expected, followed by a length, followed by the data itself.
*
* This abstract implementation does not imply anything about the encoding of
* the identifier, length or value field. This is deferred to a concrete
* implementation, e.g. a ASN.1 DER implementation.
*
* The TLV element is parsed from an associated {@link TlvInputStream}.
*
*/
abstract public class TlvElement {
protected final int identifier;
protected final byte[] buffer;
protected final int offset;
protected final int length;
protected TlvElement(int identifier, byte[] buffer) {
this(identifier, buffer, 0, buffer.length);
}
protected TlvElement(int identifier, byte[] buffer, int offset, int length) {
assert (buffer != null);
assert (buffer.length >= offset + length);
this.identifier = identifier;
this.buffer = buffer;
this.offset = offset;
this.length = length;
}
abstract public TlvInputStream createTlvInputStream(byte[] pBytes,
int pOffset, int pLength);
/**
* The data part within the TLV element.
*
* @return The data part within the TLV element.
*/
public byte[] getContent() {
byte[] data = new byte[length];
System.arraycopy(buffer, offset, data, 0, length);
return data;
}
/**
* The whole, encoded TLV element.
*
* @return The whole, encoded TLV element.
*/
abstract public byte[] getEncoded();
/**
* The identifier for this TLV element.
*
* An identifier may be made up of different components, see ASN.1.
*
* @return The identifier for this TLV element.
*/
public int getIdentifier() {
return identifier;
}
/**
* The length of the TLV elements data
*
* @return The length of the TLV elements data
*/
public int getLength() {
return length;
}
/**
* A composite {@link TlvElement} contains other {@link TlvElement}
* instances in form of a {@link TlvTemplate}.
*
* @return The contained {@link TlvTemplate} if available.
* @throws TlvFormatException
*/
public TlvTemplate getTemplate() throws TlvFormatException {
return new TlvTemplate(createTlvInputStream(buffer, offset, length));
}
/**
* true if this element contains TLV data itself.
*
* @return true if this element contains TLV data itself.
*/
abstract public boolean isComposite();
@Override
public String toString() {
return "0x" + Integer.toHexString(getIdentifier()) + ":"
+ HexTools.bytesToHexString(buffer, offset, length, true);
}
}