hostage/src/org/alfresco/jlan/client/SMBPacket.java

/*
 * Copyright (C) 2006-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
 */

package org.alfresco.jlan.client;

import java.io.*;

import org.alfresco.jlan.debug.Debug;
import org.alfresco.jlan.netbios.NetworkSession;
import org.alfresco.jlan.netbios.RFCNetBIOSProtocol;
import org.alfresco.jlan.smb.PacketType;
import org.alfresco.jlan.smb.SMBErrorText;
import org.alfresco.jlan.smb.SMBException;
import org.alfresco.jlan.smb.SMBStatus;
import org.alfresco.jlan.util.DataPacker;
import org.alfresco.jlan.util.HexDump;

/**
 *  SMB packet type class
 *  
 *  <p>Contains the details of an SMB/CIFS request or response. The SMB packet class has methods for packing
 *  and unpacking the various fields of the SMB header and requests.
 *  
 *  <p>Contains SMB/CIFS constants for SMB packet field offsets and header flag values.
 * 
 * @author gkspencer
 */
public class SMBPacket {

  //	SMB packet offsets, assuming an RFC NetBIOS transport

  public static final int SMBHEADER 		= RFCNetBIOSProtocol.HEADER_LEN;
  public static final int COMMAND 			= 4 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int ERRORCODE 		= 5 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int ERRORCLASS 		= 5 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int ERROR 			= 7 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int FLAGS 			= 9 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int FLAGS2 			= 10 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int PIDHIGH 			= 12 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int SIGNATURE			= 14 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int SID 				= 18 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int SEQNO 			= 20 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int TID 				= 24 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int PID 				= 26 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int UID 				= 28 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int MID 				= 30 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int WORDCNT 			= 32 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int ANDXCOMMAND 		= 33 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int ANDXRESERVED 		= 34 + RFCNetBIOSProtocol.HEADER_LEN;
  public static final int PARAMWORDS 		= 33 + RFCNetBIOSProtocol.HEADER_LEN;

  //	SMB packet header length for a transaction type request

  public static final int TRANS_HEADERLEN = 66 + RFCNetBIOSProtocol.HEADER_LEN;

	//	Minimum receive length for a valid SMB packet

  public static final int MIN_RXLEN = 32;

	//	Default buffer size to allocate for SMB packets

  public static final int DEFAULT_BUFSIZE = 4096;

	//	Flag bits

  public static final int FLG_SUBDIALECT 	= 0x01;
  public static final int FLG_CASELESS 		= 0x08;
  public static final int FLG_CANONICAL 	= 0x10;
  public static final int FLG_OPLOCK 		= 0x20;
  public static final int FLG_NOTIFY 		= 0x40;
  public static final int FLG_RESPONSE 		= 0x80;

	//	Flag2 bits

  public static final int FLG2_LONGFILENAMES 	= 0x0001;
  public static final int FLG2_EXTENDEDATTRIB 	= 0x0002;
  public static final int FLG2_SECURITYSIG		= 0x0004;
  public static final int FLG2_EXTENDEDSETUP	= 0x0800;
  public static final int FLG2_READIFEXE 		= 0x2000;
  public static final int FLG2_LONGERRORCODE 	= 0x4000;
  public static final int FLG2_UNICODE 			= 0x8000;

	//	Security mode bits

  public static final int SEC_USER 		= 0x0001;
  public static final int SEC_ENCRYPT 	= 0x0002;

	//	Raw mode bits

  public static final int RAW_READ 	= 0x0001;
  public static final int RAW_WRITE = 0x0002;

	//	SMB packet buffer

  private byte[] m_smbbuf;

	//	Packet type

  private int m_pkttype;

	//	Current byte area pack/unpack position
	
	protected int m_pos;
	protected int m_endpos;

	//	Time of last packet send
	
	protected long m_lastTxTime;
	
	/**
	 * Default constructor
	 */
	public SMBPacket() {
		m_smbbuf = new byte[DEFAULT_BUFSIZE];
		InitializeBuffer();
	}

	/**
	 * Construct an SMB packet using the specified packet buffer.
	 * 
	 * @param buf SMB packet buffer.
	 */
	public SMBPacket(byte[] buf) {
		m_smbbuf = buf;
	}

	/**
	 * Construct an SMB packet of the specified size.
	 * 
	 * @param siz Size of SMB packet buffer to allocate.
	 */
	public SMBPacket(int siz) {
		m_smbbuf = new byte[siz];
		InitializeBuffer();
	}

	/**
	 * Check if a received SMB is valid, if not then throw an exception
	 * 
	 * @exception SMBException
	 */
	public final void checkForError()
		throws SMBException {

		// Check if a valid SMB response has been received

		if ( isValidResponse() == false) {

			// Check for NT error codes

			if ( isLongErrorCode())
				throw new SMBException(SMBStatus.NTErr, getLongErrorCode());
			else
				throw new SMBException(getErrorClass(), getErrorCode());
		}
	}

	/**
	 * Clear the data byte count
	 */
	public final void clearBytes() {
		int offset = getByteOffset() - 2;
		DataPacker.putIntelShort(0, m_smbbuf, offset);
	}

	/**
	 * Dump the SMB packet to the debug stream
	 */
	public void DumpPacket() {

		// Dump the command type

		int pCount = getParameterCount();
		Debug.println("** SMB Packet Type: " + PacketType.getCommandName(getCommand()) + (isResponse() ? " [Response]" : ""));

		// Dump flags/secondary flags

		if ( Debug.EnableInfo && Session.hasDebugOption(Session.DBGDumpPacket)) {

			// Dump the packet length

			Debug.println("** SMB Packet Dump");
			Debug.println("Packet Length : " + getLength());
			Debug.println("Byte Offset: " + getByteOffset() + ", Byte Count: " + getByteCount());

			// Dump the flags

			Debug.println("Flags: " + getFlagsAsString());
			Debug.println("Flags2: " + getFlags2AsString());

			// Dump the security signature is signing is enabled

			if ( hasSecuritySignature())
				Debug.println("Signature: " + Long.toHexString(getSignature()));

			// Dump various ids

			Debug.print("TID=" + getTreeId());
			Debug.print(", PID=" + getProcessId());
			Debug.print(", UID=" + getUserId());
			Debug.println(", MID=" + getMultiplexId());

			// Dump parameter words/count

			Debug.println("Parameter Words: " + pCount);

			if ( pCount > 0) {
				StringBuffer str = new StringBuffer(128);

				int colCnt = (pCount + 3) & 0xFFFC;
				int curCol = 1;

				for (int i = 0; i < colCnt; i++) {

					// Check if there is a parameter to output

					if ( i < pCount) {
						str.append("P");
						str.append(Integer.toString(i + 1));
						if ( i < 9)
							str.append(" ");
						str.append("=");
						str.append(Integer.toString(getParameter(i)));
						str.append("/0x");
						str.append(Integer.toHexString(getParameter(i)));
					}

					// Pad the column

					while (str.length() < (curCol * 20))
						str.append(" ");

					if ( curCol == 4) {
						curCol = 1;
						Debug.println(str.toString());
						str.setLength(0);
					}
					else
						curCol++;
				}
			}

			// Response packet fields

			if ( isResponse()) {

				// Dump the error code

				if ( isLongErrorCode())
					Debug.println("Long error: 0x" + Integer.toHexString(getLongErrorCode()));
				else {
					Debug.print("Error text: ");
					Debug.println(SMBErrorText.ErrorString(getErrorClass(), getErrorCode()));
				}
			}
		}

		// Dump the raw data

		if ( Debug.EnableInfo && Session.hasDebugOption(Session.DBGHexDump)) {
			Debug.println("********** Raw SMB Data Dump **********");
			HexDump.Dump(m_smbbuf, getLength(), 4);
		}

		Debug.println("");
	}

	/**
	 * Check if the error class/code match the specified error/class
	 * 
	 * @param errClass int
	 * @param errCode int
	 * @return boolean
	 */
	public final boolean equalsError(int errClass, int errCode) {
		if ( getErrorClass() == errClass && getErrorCode() == errCode)
			return true;
		return false;
	}

	/**
	 * Send the SMB packet and receive the response packet
	 * 
	 * @param sess Network session to send/receive the packet over.
	 * @param rxPkt SMB packet to receive the response into.
	 * @param throwerr If true then throw an I/O error if an invalid response is received.
	 * @exception java.io.IOException If a network error occurs.
	 * @exception SMBException If an SMB level error occurs
	 */
	protected final synchronized void ExchangeLowLevelSMB(NetworkSession sess, SMBPacket rxPkt, boolean throwerr)
		throws java.io.IOException, SMBException {

		// Set multiplex id

		if ( getMultiplexId() == 0)
			setMultiplexId(1);

		// DEBUG

		if ( Session.hasDebug())
			DumpPacket();

		// Send the SMB request

		sess.Send(m_smbbuf, getLength());

		// Receive a response

		if ( sess.Receive(rxPkt.getBuffer()) >= MIN_RXLEN) {

			// Check if the response is for the current request

			if ( rxPkt.getCommand() == m_pkttype) {

				// DEBUG

				if ( Session.hasDebug())
					rxPkt.DumpPacket();

				// Check if a valid SMB response has been received

				if ( throwerr == true)
					checkForError();

				// Valid packet received, return to caller

				return;
			}
		}

		// Invalid receive packet

		throw new java.io.IOException("Invalid SMB Receive Packet");
	}

	/**
	 * Send/receive an SMB protocol packet to the remote server.
	 * 
	 * @param sess SMB session to send/receive data on.
	 * @param rxPkt SMB packet to receive the response into.
	 * @exception java.io.IOException If an I/O error occurs.
	 * @exception SMBException If an SMB level error occurs.
	 */
	public synchronized final void ExchangeSMB(Session sess, SMBPacket rxPkt)
		throws SMBException, IOException {

		// Call the main SMB exhchange method

		ExchangeSMB(sess, rxPkt, false);
	}

	/**
	 * Send the SMB packet and receive the response packet
	 * 
	 * @param sess SMB session to send/receive the packet over.
	 * @param rxPkt SMB packet to receive the response into.
	 * @param throwerr If true then throw an I/O error if an invalid response is received.
	 * @exception java.io.IOException If an I/O error occurs.
	 * @exception SMBException If an SMB level error occurs.
	 */
	public synchronized final void ExchangeSMB(Session sess, SMBPacket rxPkt, boolean throwerr)
		throws SMBException, IOException {

		// Set the process id, user id and multiplex id

		setProcessId(sess.getProcessId());
		setUserId(sess.getUserId());

		if ( getMultiplexId() == 0)
			setMultiplexId(1);

		// DEBUG

		if ( Session.hasDebug())
			DumpPacket();

		// Get the network session

		NetworkSession netSess = sess.getSession();

		// Check if SMB signing is enabled, if so then set the SMB signature for the request

		if ( sess.hasSMBSigning())
			sess.signTxPacket(this);

		// Send the SMB request

		netSess.Send(m_smbbuf, getLength());

		// Receive the response, other asynchronous responses may be received before the response
		// for this request

		boolean rxValid = false;

		while (rxValid == false) {

			// Receive a response

			if ( netSess.Receive(rxPkt.getBuffer()) >= MIN_RXLEN) {

				// Check if the response is for the current request

				if ( rxPkt.getCommand() == m_pkttype) {

					// Check if SMB signing is enabled and received packet signatures should be
					// checked

					if ( sess.hasSMBSigning() && SessionFactory.isReceivedSMBSigningEnabled())
						sess.verifyRxPacket(this);

					// DEBUG

					if ( Session.hasDebug())
						rxPkt.DumpPacket();

					// Check if a valid SMB response has been received, done before checking SMB
					// signatures

					if ( throwerr == true)
						checkForError();

					// Valid packet received, return to caller

					return;
				}

				// Asynchronous response received, pass the packet to the session for processing

				sess.processAsynchResponse(rxPkt);
			}
		}

		// Invalid receive packet

		throw new java.io.IOException("Invalid SMB Receive Packet");
	}

	/**
	 * Get the secondary command code
	 * 
	 * @return Secondary command code
	 */
	public final int getAndXCommand() {
		return (int) (m_smbbuf[ANDXCOMMAND] & 0xFF);
	}

	/**
	 * Return the byte array used for the SMB packet
	 * 
	 * @return Byte array used for the SMB packet.
	 */
	public final byte[] getBuffer() {
		return m_smbbuf;
	}

	/**
	 * Return the total buffer size available to the SMB request
	 * 
	 * @return Total SMB buffer length available.
	 */
	public final int getBufferLength() {
		return m_smbbuf.length - RFCNetBIOSProtocol.HEADER_LEN;
	}

	/**
	 * Return the available buffer space for data bytes
	 * 
	 * @return int
	 */
	public final int getAvailableLength() {
		return m_smbbuf.length - DataPacker.longwordAlign(getByteOffset());
	}

	/**
	 * Get the data byte count for the SMB packet
	 * 
	 * @return Data byte count
	 */
	public final int getByteCount() {

		// Calculate the offset of the byte count

		int pos = PARAMWORDS + (2 * getParameterCount());
		return (int) DataPacker.getIntelShort(m_smbbuf, pos);
	}

	/**
	 * Get the data byte area offset within the SMB packet
	 * 
	 * @return Data byte offset within the SMB packet.
	 */
	public final int getByteOffset() {

		// Calculate the offset of the byte buffer

		int pCnt = getParameterCount();
		int pos = WORDCNT + (2 * pCnt) + 3;
		return pos;
	}

	/**
	 * Get the SMB command
	 * 
	 * @return SMB command code.
	 */
	public final int getCommand() {
		return (int) (m_smbbuf[COMMAND] & 0xFF);
	}

	/**
	 * Determine if normal or long error codes have been returned
	 * 
	 * @return boolean
	 */
	public final boolean hasLongErrorCode() {
		if ( (getFlags2() & FLG2_LONGERRORCODE) == 0)
			return false;
		return true;
	}

	/**
	 * Determine if security signatures are being used
	 * 
	 * @return boolean
	 */
	public final boolean hasSecuritySignature() {
		if ( (getFlags2() & FLG2_SECURITYSIG) == 0)
			return false;
		return true;
	}

	/**
	 * Determine if extended session setup is being used
	 * 
	 * @return boolean
	 */
	public final boolean hasExtendedSetup() {
		if ( (getFlags2() & FLG2_EXTENDEDSETUP) == 0)
			return false;
		return true;
	}

	/**
	 * Return the saved packet type
	 * 
	 * @return int
	 */
	public final int isType() {
		return m_pkttype;
	}

	/**
	 * Check if the packet contains ASCII or Unicode strings
	 * 
	 * @return boolean
	 */
	public final boolean isUnicode() {
		return (getFlags2() & FLG2_UNICODE) != 0 ? true : false;
	}

	/**
	 * Check if the packet is using caseless filenames
	 * 
	 * @return boolean
	 */
	public final boolean isCaseless() {
		return (getFlags() & FLG_CASELESS) != 0 ? true : false;
	}

	/**
	 * Check if long file names are being used
	 * 
	 * @return boolean
	 */
	public final boolean isLongFileNames() {
		return (getFlags2() & FLG2_LONGFILENAMES) != 0 ? true : false;
	}

	/**
	 * Check if long error codes are being used
	 * 
	 * @return boolean
	 */
	public final boolean isLongErrorCode() {
		return (getFlags2() & FLG2_LONGERRORCODE) != 0 ? true : false;
	}

	/**
	 * Get the SMB error class
	 * 
	 * @return SMB error class.
	 */
	public final int getErrorClass() {
		return (int) m_smbbuf[ERRORCLASS] & 0xFF;
	}

	/**
	 * Get the SMB error code
	 * 
	 * @return SMB error code.
	 */
	public final int getErrorCode() {
		return (int) m_smbbuf[ERROR] & 0xFF;
	}

	/**
	 * Get the SMB flags value.
	 * 
	 * @return SMB flags value.
	 */
	public final int getFlags() {
		return (int) m_smbbuf[FLAGS] & 0xFF;
	}

	/**
	 * Get the SMB flags2 value.
	 * 
	 * @return SMB flags2 value.
	 */
	public final int getFlags2() {
		return (int) DataPacker.getIntelShort(m_smbbuf, FLAGS2);
	}

	/**
	 * Calculate the total used packet length.
	 * 
	 * @return Total used packet length.
	 */
	public final int getLength() {
		return (getByteOffset() + getByteCount()) - RFCNetBIOSProtocol.HEADER_LEN;
	}

	/**
	 * Get the long SMB error code
	 * 
	 * @return Long SMB error code.
	 */
	public final int getLongErrorCode() {
		return DataPacker.getIntelInt(m_smbbuf, ERRORCODE);
	}

	/**
	 * Get the multiplex identifier.
	 * 
	 * @return Multiplex identifier.
	 */
	public final int getMultiplexId() {
		return DataPacker.getIntelShort(m_smbbuf, MID);
	}

	/**
	 * Get a parameter word from the SMB packet.
	 * 
	 * @param idx Parameter index (zero based).
	 * @return Parameter word value.
	 * @exception java.lang.IndexOutOfBoundsException If the parameter index is out of range.
	 */
	public final int getParameter(int idx)
		throws java.lang.IndexOutOfBoundsException {

		// Range check the parameter index

		if ( idx > getParameterCount())
			throw new java.lang.IndexOutOfBoundsException();

		// Calculate the parameter word offset

		int pos = WORDCNT + (2 * idx) + 1;
		return (int) (DataPacker.getIntelShort(m_smbbuf, pos) & 0xFFFF);
	}

	/**
	 * Get the specified parameter words, as an int value.
	 * 
	 * @param idx Parameter index (zero based).
	 * @return int
	 */
	public final int getParameterLong(int idx) {
		int pos = WORDCNT + (2 * idx) + 1;
		return DataPacker.getIntelInt(m_smbbuf, pos);
	}

	/**
	 * Get the parameter count
	 * 
	 * @return Parameter word count.
	 */
	public final int getParameterCount() {
		return (int) m_smbbuf[WORDCNT];
	}

	/**
	 * Get the process indentifier (PID)
	 * 
	 * @return Process identifier value.
	 */
	public final int getProcessId() {
		return DataPacker.getIntelShort(m_smbbuf, PID);
	}

	/**
	 * Get the SMB signing value, as a long value
	 * 
	 * @return long
	 */
	public final long getSignature() {
		return DataPacker.getIntelLong(m_smbbuf, SIGNATURE);
	}

	/**
	 * Get the tree identifier (TID)
	 * 
	 * @return Tree identifier (TID)
	 */
	public final int getTreeId() {
		return DataPacker.getIntelShort(m_smbbuf, TID);
	}

	/**
	 * Get the user identifier (UID)
	 * 
	 * @return User identifier (UID)
	 */
	public final int getUserId() {
		return DataPacker.getIntelShort(m_smbbuf, UID);
	}

	/**
	 * Return the last sent packet time
	 * 
	 * @return long
	 */
	public final long getLastPacketSendTime() {
		return m_lastTxTime;
	}

	/**
	 * Initialize the SMB packet buffer.
	 */
	private final void InitializeBuffer() {

		// Set the packet signature

		m_smbbuf[SMBHEADER] = (byte) 0xFF;
		m_smbbuf[SMBHEADER + 1] = (byte) 'S';
		m_smbbuf[SMBHEADER + 2] = (byte) 'M';
		m_smbbuf[SMBHEADER + 3] = (byte) 'B';
	}

	/**
	 * Determine if this packet is an SMB response, or command packet
	 * 
	 * @return true if this SMB packet is a response, else false
	 */
	public final boolean isResponse() {
		int resp = getFlags();
		if ( (resp & FLG_RESPONSE) != 0)
			return true;
		return false;
	}

	/**
	 * Check if this is an SMB request packet
	 * 
	 * @return boolean
	 */
	public final boolean isRequest() {
		return ( getFlags() & FLG_RESPONSE) == 0 ? true : false;
	}
	
	/**
	 * Check if the response packet is valid, ie. type and flags
	 * 
	 * @return true if the SMB packet is a response packet and the response is valid, else false.
	 */
	public final boolean isValidResponse() {

		// Check if this is a response packet, and the correct type of packet

		if ( isResponse() && getCommand() == m_pkttype) {

			// Check if standard error codes or NT 32-bit error codes are being used

			if ( (getFlags2() & FLG2_LONGERRORCODE) == 0) {
				if ( getErrorCode() == SMBStatus.Success)
					return true;
			}
			else if ( getLongErrorCode() == SMBStatus.NTSuccess)
				return true;
		}
		return false;
	}

	/**
	 * Pack a byte (8 bit) value into the byte area
	 * 
	 * @param val byte
	 */
	public final void packByte(byte val) {
		m_smbbuf[m_pos++] = val;
	}

	/**
	 * Pack a byte (8 bit) value into the byte area
	 * 
	 * @param val int
	 */
	public final void packByte(int val) {
		m_smbbuf[m_pos++] = (byte) val;
	}

	/**
	 * Pack the specified bytes into the byte area
	 * 
	 * @param byts byte[]
	 * @param len int
	 */
	public final void packBytes(byte[] byts, int len) {
		System.arraycopy(byts, 0, m_smbbuf, m_pos, len);
		m_pos += len;
	}

	/**
	 * Pack a string using either ASCII or Unicode into the byte area
	 * 
	 * @param str String
	 * @param uni boolean
	 */
	public final void packString(String str, boolean uni) {

		// Check for Unicode or ASCII

		if ( uni) {

			// Word align the buffer position, pack the Unicode string

			m_pos = DataPacker.wordAlign(m_pos);
			DataPacker.putUnicodeString(str, m_smbbuf, m_pos, true);
			m_pos += (str.length() * 2) + 2;
		}
		else {

			// Pack the ASCII string

			DataPacker.putString(str, m_smbbuf, m_pos, true);
			m_pos += str.length() + 1;
		}
	}

	/**
	 * Pack a word (16 bit) value into the byte area
	 * 
	 * @param val int
	 */
	public final void packWord(int val) {
		DataPacker.putIntelShort(val, m_smbbuf, m_pos);
		m_pos += 2;
	}

	/**
	 * Pack a 32 bit integer value into the byte area
	 * 
	 * @param val int
	 */
	public final void packInt(int val) {
		DataPacker.putIntelInt(val, m_smbbuf, m_pos);
		m_pos += 4;
	}

	/**
	 * Pack a long integer (64 bit) value into the byte area
	 * 
	 * @param val long
	 */
	public final void packLong(long val) {
		DataPacker.putIntelLong(val, m_smbbuf, m_pos);
		m_pos += 8;
	}

	/**
	 * Return the current byte area buffer position
	 * 
	 * @return int
	 */
	public final int getPosition() {
		return m_pos;
	}

	/**
	 * Set the byte area buffer position
	 * 
	 * @param pos int
	 */
	public final void setPosition(int pos) {
		m_pos = pos;
	}

	/**
	 * Unpack a byte value from the byte area
	 * 
	 * @return int
	 */
	public final int unpackByte() {
		return (int) m_smbbuf[m_pos++];
	}

	/**
	 * Unpack a block of bytes from the byte area
	 * 
	 * @param len int
	 * @return byte[]
	 */
	public final byte[] unpackBytes(int len) {
		if ( len <= 0)
			return null;

		byte[] buf = new byte[len];
		System.arraycopy(m_smbbuf, m_pos, buf, 0, len);
		m_pos += len;
		return buf;
	}

	/**
	 * Unpack a word (16 bit) value from the byte area
	 * 
	 * @return int
	 */
	public final int unpackWord() {
		int val = DataPacker.getIntelShort(m_smbbuf, m_pos);
		m_pos += 2;
		return val;
	}

	/**
	 * Unpack an integer (32 bit) value from the byte/parameter area
	 * 
	 * @return int
	 */
	public final int unpackInt() {
		int val = DataPacker.getIntelInt(m_smbbuf, m_pos);
		m_pos += 4;
		return val;
	}

	/**
	 * Unpack a long integer (64 bit) value from the byte area
	 * 
	 * @return long
	 */
	public final long unpackLong() {
		long val = DataPacker.getIntelLong(m_smbbuf, m_pos);
		m_pos += 8;
		return val;
	}

	/**
	 * Unpack a string from the byte area
	 * 
	 * @param uni boolean
	 * @return String
	 */
	public final String unpackString(boolean uni) {

		// Check for Unicode or ASCII

		String ret = null;

		if ( uni) {

			// Word align the current buffer position

			m_pos = DataPacker.wordAlign(m_pos);
			ret = DataPacker.getUnicodeString(m_smbbuf, m_pos, 255);
			if ( ret != null)
				m_pos += (ret.length() * 2) + 2;
		}
		else {

			// Unpack the ASCII string

			ret = DataPacker.getString(m_smbbuf, m_pos, 255);
			if ( ret != null)
				m_pos += ret.length() + 1;
		}

		// Return the string

		return ret;
	}

	/**
	 * Unpack a string from the byte area
	 * 
	 * @param len int
	 * @param uni boolean
	 * @return String
	 */
	public final String unpackString(int len, boolean uni) {

		// Check for Unicode or ASCII

		String ret = null;

		if ( uni) {

			// Word align the current buffer position

			m_pos = DataPacker.wordAlign(m_pos);
			ret = DataPacker.getUnicodeString(m_smbbuf, m_pos, len);
			if ( ret != null)
				m_pos += (ret.length() * 2);
		}
		else {

			// Unpack the ASCII string

			ret = DataPacker.getString(m_smbbuf, m_pos, len);
			if ( ret != null)
				m_pos += ret.length();
		}

		// Return the string

		return ret;
	}

	/**
	 * Check if there is more data in the byte area
	 * 
	 * @return boolean
	 */
	public final boolean hasMoreData() {
		if ( m_pos < m_endpos)
			return true;
		return false;
	}

	/**
	 * Receive an SMB packet on the spceified SMB session.
	 * 
	 * @param sess SMB session to receive the packet on.
	 * @exception java.io.IOException If a network error occurs
	 * @exception SMBException If an SMB level error occurs
	 */
	protected final void ReceiveSMB(Session sess)
		throws java.io.IOException, SMBException {

		// Call the main receive method

		ReceiveSMB(sess, true);
	}

	/**
	 * Receive an SMB packet on the spceified SMB session.
	 * 
	 * @param sess SMB session to receive the packet on.
	 * @param throwErr Flag to indicate if an error is thrown if an error response is received
	 * @exception java.io.IOException If a network error occurs
	 * @exception SMBException If an SMB level error occurs
	 */
	protected final void ReceiveSMB(Session sess, boolean throwErr)
		throws java.io.IOException, SMBException {

		// Get the network session

		NetworkSession netSess = sess.getSession();

		// Receive the response, other asynchronous responses may be received before the response
		// for this request

		boolean rxValid = false;

		while (rxValid == false) {

			// Receive a response

			if ( netSess.Receive(getBuffer()) >= MIN_RXLEN) {

				// Check if the response is for the current request

				if ( getCommand() == m_pkttype) {

					// DEBUG

					if ( Session.hasDebug())
						DumpPacket();

					// Check if SMB signing is enabled and received packet signatures should be
					// checked

					if ( sess.hasSMBSigning() && SessionFactory.isReceivedSMBSigningEnabled())
						sess.verifyRxPacket(this);

					// Check if a valid SMB response has been received

					if ( throwErr == true)
						checkForError();

					// Valid packet received, return to caller

					return;
				}

				// Asynchronous response received, pass the packet to the session for processing

				sess.processAsynchResponse(this);
			}
			else {

				// Not enough data received for an SMB header

				throw new java.io.IOException("Short NetBIOS receive");
			}
		}
	}

	/**
	 * Receive an asynchronous SMB response from the server
	 * 
	 * @param sess Session
	 * @param waitTime Receive timeout in milliseconds, or zero for no timeout
	 * @throws java.io.IOException
	 * @throws SMBException
	 */
	protected final void ReceiveAsynchSMB(Session sess, int waitTime)
		throws java.io.IOException, SMBException {

		// Get the network session

		NetworkSession netSess = sess.getSession();
		netSess.setTimeout(waitTime);

		// Receive, or wait for, a response

		if ( netSess.Receive(getBuffer()) >= MIN_RXLEN) {

			// Asynchronous response received, pass the packet to the session for processing

			sess.processAsynchResponse(this);
		}
		else {

			// Not enough data received for an SMB header

			throw new java.io.IOException("Short NetBIOS receive");
		}
	}

	/**
	 * Send the SMB packet on the specified SMB session.
	 * 
	 * @param sess SMB session to send this packet over.
	 * @exception java.io.IOException If an I/O error occurs.
	 */
	protected final void SendSMB(Session sess)
		throws java.io.IOException {

		// DEBUG

		if ( Session.hasDebug())
			DumpPacket();

		// Update the last send time

		m_lastTxTime = System.currentTimeMillis();

		// Check if SMB signing is enabled, if so then set the SMB signature for the request

		if ( sess.hasSMBSigning())
			sess.signTxPacket(this);

		// Send the SMB request

		sess.getSession().Send(m_smbbuf, getLength());
	}

	/**
	 * Set the secondary SMB command
	 * 
	 * @param cmd Secondary SMB command code.
	 */
	public final void setAndXCommand(int cmd) {

		// Set the chained command packet type

		m_smbbuf[ANDXCOMMAND] = (byte) cmd;
		m_smbbuf[ANDXRESERVED] = (byte) 0;

		// If the AndX command is disabled clear the offset to the chained packet

		if ( cmd == PacketType.NoChainedCommand)
			setParameter(1, 0);
	}

	/**
	 * Set the data byte count for this SMB packet
	 * 
	 * @param cnt Data byte count.
	 */
	public final void setByteCount(int cnt) {
		int offset = getByteOffset() - 2;
		DataPacker.putIntelShort(cnt, m_smbbuf, offset);
	}

	/**
	 * Set the data byte count for this SMB packet
	 */

	public final void setByteCount() {
		int offset = getByteOffset() - 2;
		int len = m_pos - getByteOffset();
		DataPacker.putIntelShort(len, m_smbbuf, offset);
	}

	/**
	 * Set the data byte area in the SMB packet
	 * 
	 * @param byts Byte array containing the data to be copied to the SMB packet.
	 */
	public final void setBytes(byte[] byts) {
		int offset = getByteOffset() - 2;
		DataPacker.putIntelShort(byts.length, m_smbbuf, offset);

		offset += 2;

		for (int idx = 0; idx < byts.length; m_smbbuf[offset + idx] = byts[idx++])
			;
	}

	/**
	 * Set the SMB command
	 * 
	 * @param cmd SMB command code
	 */
	public final void setCommand(int cmd) {
		m_pkttype = cmd;
		m_smbbuf[COMMAND] = (byte) cmd;
	}

	/**
	 * Set the SMB error class.
	 * 
	 * @param cl SMB error class.
	 */
	public final void setErrorClass(int cl) {
		m_smbbuf[ERRORCLASS] = (byte) (cl & 0xFF);
	}

	/**
	 * Set the SMB error code
	 * 
	 * @param sts SMB error code.
	 */
	public final void setErrorCode(int sts) {
		m_smbbuf[ERROR] = (byte) (sts & 0xFF);
	}

	/**
	 * Set a long error code (NT status code)
	 * 
	 * @param lsts int
	 */
	public final void setLongErrorCode(int lsts) {
		DataPacker.putIntelInt(lsts, m_smbbuf, ERRORCODE);
	}

	/**
	 * Set the SMB flags value.
	 * 
	 * @param flg SMB flags value.
	 */
	public final void setFlags(int flg) {
		m_smbbuf[FLAGS] = (byte) flg;
	}

	/**
	 * Set the SMB flags2 value.
	 * 
	 * @param flg SMB flags2 value.
	 */
	public final void setFlags2(int flg) {
		DataPacker.putIntelShort(flg, m_smbbuf, FLAGS2);
	}

	/**
	 * Set the multiplex identifier.
	 * 
	 * @param mid Multiplex identifier
	 */
	public final void setMultiplexId(int mid) {
		DataPacker.putIntelShort(mid, m_smbbuf, MID);
	}

	/**
	 * Set the specified parameter word.
	 * 
	 * @param idx Parameter index (zero based).
	 * @param val Parameter value.
	 */
	public final void setParameter(int idx, int val) {
		int pos = WORDCNT + (2 * idx) + 1;
		DataPacker.putIntelShort(val, m_smbbuf, pos);
	}

	/**
	 * Set the specified parameter words.
	 * 
	 * @param idx Parameter index (zero based).
	 * @param val Parameter value.
	 */

	public final void setParameterLong(int idx, int val) {
		int pos = WORDCNT + (2 * idx) + 1;
		DataPacker.putIntelInt(val, m_smbbuf, pos);
	}

	/**
	 * Set the parameter count
	 * 
	 * @param cnt Parameter word count.
	 */
	public final void setParameterCount(int cnt) {
		m_smbbuf[WORDCNT] = (byte) cnt;
	}

	/**
	 * Set the process identifier value (PID).
	 * 
	 * @param pid Process identifier value.
	 */
	public final void setProcessId(int pid) {
		DataPacker.putIntelShort(pid, m_smbbuf, PID);
	}

	/**
	 * Set the packet sequence number, for connectionless commands.
	 * 
	 * @param seq Sequence number.
	 */
	public final void setSeqNo(int seq) {
		DataPacker.putIntelShort(seq, m_smbbuf, SEQNO);
	}

	/**
	 * Set the session id.
	 * 
	 * @param sid Session id.
	 */
	public final void setSID(int sid) {
		DataPacker.putIntelShort(sid, m_smbbuf, SID);
	}

	/**
	 * Set the SMB signing signature
	 * 
	 * @param ival int
	 */
	public final void setSignature(int ival) {
		DataPacker.putIntelInt(ival, m_smbbuf, SIGNATURE);
		DataPacker.putZeros(m_smbbuf, SIGNATURE + 4, 4);
	}

	/**
	 * Set the SMB signing signature
	 * 
	 * @param lval long
	 */
	public final void setSignature(long lval) {
		DataPacker.putIntelLong(lval, m_smbbuf, SIGNATURE);
	}

	/**
	 * Set the SMB signing signature
	 * 
	 * @param byts byte[]
	 * @param offset int
	 */
	public final void setSignature(byte[] byts, int offset) {
		System.arraycopy(byts, offset, m_smbbuf, SIGNATURE, 8);
	}

	/**
	 * Set the tree identifier (TID)
	 * 
	 * @param tid Tree identifier value.
	 */
	public final void setTreeId(int tid) {
		DataPacker.putIntelShort(tid, m_smbbuf, TID);
	}

	/**
	 * Set the user identifier (UID)
	 * 
	 * @param uid User identifier value.
	 */
	public final void setUserId(int uid) {
		DataPacker.putIntelShort(uid, m_smbbuf, UID);
	}

	/**
	 * Align the byte area pointer on an int (32bit) boundary
	 */
	public final void alignBytePointer() {
		m_pos = DataPacker.longwordAlign(m_pos);
	}

	/**
	 * Reset the byte/parameter pointer area for packing/unpacking data items from the packet
	 */
	public final void resetBytePointer() {
		m_pos = getByteOffset();
		m_endpos = m_pos + getByteCount();
	}

	/**
	 * Reset the byte/parameter pointer area for packing/unpacking data items from the packet, and
	 * align the buffer on an int (32bit) boundary
	 */
	public final void resetBytePointerAlign() {
		m_pos = DataPacker.longwordAlign(getByteOffset());
		m_endpos = m_pos + getByteCount();
	}

	/**
	 * Reset the byte/parameter pointer area for packing/unpacking paramaters from the packet
	 */
	public final void resetParameterPointer() {
		m_pos = PARAMWORDS;
	}

	/**
	 * Set the unpack pointer to the specified offset, for AndX processing
	 * 
	 * @param off int
	 * @param len int
	 */
	public final void setBytePointer(int off, int len) {
		m_pos = off;
		m_endpos = m_pos + len;
	}

	/**
	 * Skip a number of bytes in the parameter/byte area
	 * 
	 * @param cnt int
	 */
	public final void skipBytes(int cnt) {
		m_pos += cnt;
	}

	/**
	 * Return the flags value as a string
	 * 
	 * @return String
	 */
	protected final String getFlagsAsString() {

		// Get the flags value

		int flags = getFlags();
		if ( flags == 0)
			return "<None>";

		StringBuffer str = new StringBuffer();
		if ( (flags & FLG_SUBDIALECT) != 0)
			str.append("SubDialect,");

		if ( (flags & FLG_CASELESS) != 0)
			str.append("Caseless,");

		if ( (flags & FLG_CANONICAL) != 0)
			str.append("Canonical,");

		if ( (flags & FLG_OPLOCK) != 0)
			str.append("Oplock,");

		if ( (flags & FLG_NOTIFY) != 0)
			str.append("Notify,");

		if ( (flags & FLG_RESPONSE) != 0)
			str.append("Response,");

		str.setLength(str.length() - 1);

		return str.toString();
	}

	/**
	 * Return the flags2 value as a string
	 * 
	 * @return String
	 */
	protected final String getFlags2AsString() {

		// Get the flags2 value

		int flags2 = getFlags2();

		if ( flags2 == 0)
			return "<None>";

		StringBuffer str = new StringBuffer();

		if ( (flags2 & FLG2_LONGFILENAMES) != 0)
			str.append("LongFilenames,");

		if ( (flags2 & FLG2_EXTENDEDATTRIB) != 0)
			str.append("ExtAttributes,");

		if ( (flags2 & FLG2_SECURITYSIG) != 0)
			str.append("SecuritySignatures,");

		if ( (flags2 & FLG2_EXTENDEDSETUP) != 0)
			str.append("ExtendedSetup,");

		if ( (flags2 & FLG2_READIFEXE) != 0)
			str.append("ReadIfEXE,");

		if ( (flags2 & FLG2_LONGERRORCODE) != 0)
			str.append("LongErrorCode,");

		if ( (flags2 & FLG2_UNICODE) != 0)
			str.append("Unicode,");

		str.setLength(str.length() - 1);

		return str.toString();
	}
}