/*
 * Copyright (C) 2006-2008 Alfresco Software Limited.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */

package org.alfresco.jlan.smb.dcerpc;

import org.alfresco.jlan.util.DataPacker;

/**
 * DCE Data Packer Class
 * 
 * <p>Contains static methods for packing/unpacking different data types into a byte buffer.
 *
 * @author gkspencer
 */
public class DCEDataPacker {

	/**
	 * Unpack a DCE string from the buffer
	 * 
	 * @param buf byte[]
	 * @param off int
	 * @return String
   * @exception  java.lang.IndexOutOfBoundsException   If there is not enough data in the buffer.
   */
	public final static String getDCEString(byte[] buf, int off)
		throws IndexOutOfBoundsException {
	
		//	Check if the buffer is big enough to hold the String header
		
		if ( buf.length < off+12)
			throw new IndexOutOfBoundsException();
			
		//	Get the maximum and actual string length
		
		int maxLen = DataPacker.getIntelInt(buf,off);
		int strLen = DataPacker.getIntelInt(buf,off+8);
		
		//	Read the Unicode string
		
		return DataPacker.getUnicodeString(buf,off+12,strLen);
	}
	
	/**
	 * Pack a DCE string into the buffer
	 * 
	 * @param buf byte[]
	 * @param off int
	 * @param str String
	 * @param incNul boolean
	 * @return int
	 */
	public final static int putDCEString(byte[] buf, int off, String str, boolean incNul) {
	  
	  //	Pack the string header
	  
	  DataPacker.putIntelInt(str.length() + 1,buf,off);
	  DataPacker.putZeros(buf,off+4,4);
	  
	  if ( incNul == false)
	  	DataPacker.putIntelInt(str.length(), buf, off+8);
	  else
	  	DataPacker.putIntelInt(str.length() + 1, buf, off+8);
	  
	  //	Pack the string

	 	return DataPacker.putUnicodeString(str,buf,off+12,incNul);
	}
	
	/**
	 * Align a buffer offset on a longword boundary
	 * 
	 * @param pos int
	 * @return int
	 */
	public final static int wordAlign(int pos) {
	  return ( pos + 1) & 0xFFFFFFFE;
	}
	
	/**
	 * Align a buffer offset on a longword boundary
	 * 
	 * @param pos int
	 * @return int
	 */
	public final static int longwordAlign(int pos) {
	  return ( pos + 3) & 0xFFFFFFFC;
	}
}