src/org/simalliance/openmobileapi/service/security/gpac/dataobjects/AID_REF_DO.java

/*
 * Copyright 2012 Giesecke & Devrient GmbH.
 *
 * 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.
 */
package org.simalliance.openmobileapi.service.security.gpac.dataobjects;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Arrays;


/**
 * The AID-REF-DO is used for retrieving and storing 
 * the corresponding access rules for an SE application 
 * (which is identified by its AID) from and to the ARA. 
 * Two different AID reference data objects exist and one 
 * of these can be chosen and applied for 
 * a GET DATA and STORE DATA command
 * 
 * 
 *
 */
public class AID_REF_DO extends BerTlv {

	public final static int _TAG = 0x4F;
	public final static int _TAG_DEFAULT_APPLICATION = 0xC0;
	
	private byte[] mAid = null;
	
	public AID_REF_DO(byte[] rawData, int tag, int valueIndex, int valueLength) {
		super(rawData, tag, valueIndex, valueLength);
	}

	
	public AID_REF_DO( int tag, byte[] aid){
		super( aid, tag, 0, (aid==null ?  0 : aid.length));
		mAid = aid;
	}

	public AID_REF_DO( int tag){
		super( null, tag, 0, 0);
		mAid = tag == _TAG_DEFAULT_APPLICATION ? null : new byte[0];
	}
	
	@Override
	public String toString(){
		StringBuilder b = new StringBuilder();
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		b.append("AID_REF_DO: ");
		try {
			this.build(out);
			b.append(BerTlv.toHex(out.toByteArray()));
		} catch (Exception e ){
			b.append(e.getLocalizedMessage());
		}
		return b.toString();
	}
	
	public byte[] getAid(){
		return mAid;
	}
	
	/**
	 * Tags: C0 -> Length: 0 -> Default selected application (all channels)
	 * 		 4F -> Length: 0 or 5 - 16 bytes
	 *
	 * Value:
	 * AID: identifies a specific application
	 * Empty: refers to all SE applications
	 * 
	 * Length:
	 * 5-16 for an AID according to ISO/IEC7816-5
	 * 0 for empty value field
 	 */
	@Override
	public void interpret() 
		throws ParserException {
	
		mAid = null;
		
		byte[] data = getRawData();
		int index = getValueIndex();

		if( getTag() == _TAG_DEFAULT_APPLICATION ) {
			if( getValueLength() != 0 ){
				throw new ParserException("Invalid value length for AID-REF-DO!");
			}
		} else if( getTag() == _TAG ){
			
			// sanity checks
			if( (getValueLength() < 5 || getValueLength() > 16) && getValueLength() != 0) {
				throw new ParserException("Invalid value length for AID-REF-DO!");
			}

			if( index + getValueLength() > data.length){
				throw new ParserException( "Not enough data for AID-REF-DO!");
			}
			
			mAid = new byte[getValueLength()];
			System.arraycopy(data, index, mAid, 0, getValueLength());
			
		} else {
			throw new ParserException( "Invalid Tag for AID-REF-DO!");
		}
	}
	
	/**
	 * Tags: C0 -> Length: 0 -> Default selected application (all channels)
	 * 		 4F -> Length: 0 or 5 - 16 bytes
	 *
	 * Value:
	 * AID: identifies a specific application
	 * Empty: refers to all SE applications
	 * 
	 * Length:
	 * 5-16 for an AID according to ISO/IEC7816-5
	 * 0 for empty value field
 	 */
	@Override
	public void build( ByteArrayOutputStream stream) 
		throws DO_Exception {
		
		if( getTag() == _TAG_DEFAULT_APPLICATION ) {
			if( mAid != null ){
				throw new DO_Exception("No value allowed for default selected application!");
			}
			stream.write(getTag());
			stream.write(0x00);
		} else if( getTag() == _TAG ){
			
			// sanity check
			if( getValueLength() != 0 ) {
				if (getValueLength() < 5 || getValueLength() > 16) {
					throw new DO_Exception("Invalid length of AID!");
				}
			}

			stream.write(getTag());
			if( mAid != null && mAid.length > 0 ) {
				stream.write(mAid.length);
				try {
					stream.write(mAid);
				} catch( IOException ioe ){
					throw new DO_Exception("AID could not be written!");
				}
			} else {
				stream.write(0x00);
			}
			
		} else {
			throw new DO_Exception( "AID-REF-DO must either be C0 or 4F!");
		}
	}
	
	@Override
	public boolean equals( Object obj ){
		boolean equals = false;
		
		if( obj instanceof AID_REF_DO ){
			equals = super.equals(obj);
			
			if( equals ){
				AID_REF_DO aid_ref_do = (AID_REF_DO)obj;
				if( this.mAid == null && aid_ref_do.mAid == null )
					equals &= true;
				else {
					equals &= Arrays.equals(mAid, aid_ref_do.mAid);
				}
			}
		}
		return equals;
	}
}