packet.java

类似QQ的功能

/*******************************************************************************
 Jimm - Mobile Messaging - J2ME ICQ clone
 Copyright (C) 2003-05  Jimm Project

 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 ********************************************************************************
 File: src/jimm/comm/Packet.java
 Version: ###VERSION###  Date: ###DATE###
 Author(s): Manuel Linsmayer, Andreas Rossbacher
 *******************************************************************************/

package jimm.comm;

import jimm.JimmException;

public class Packet
{

	// Channel constants
	public static final int CHANNEL_CONNECT = 0x01;

	public static final int CHANNEL_SNAC = 0x02;

	public static final int CHANNEL_ERROR = 0x03;

	public static final int CHANNEL_DISCONNECT = 0x04;

	public static final int CHANNEL_PING = 0x05;

	// FLAP sequence number
	protected int sequence;

	protected int flapChannel;

	protected byte[] flapData;

	// Returns the FLAP sequence number
	public int getSequence()
	{
		return (this.sequence);
	}

	// Sets the FLAP sequence number
	public void setSequence(int sequence)
	{
		this.sequence = sequence;
	}

	protected Packet()
	{
	}

	public Packet(int channel, byte[] data)
	{
		flapChannel = channel;
		flapData = data;
	}

	// Returns the package as byte array
	public byte[] toByteArray()
	{
		byte[] buf = new byte[6 + flapData.length];
		Util.putByte(buf, 0, 0x2a);
		Util.putByte(buf, 1, flapChannel);
		Util.putWord(buf, 2, this.sequence);
		Util.putWord(buf, 4, flapData.length);
		System.arraycopy(flapData, 0, buf, 6, flapData.length);
		return buf;
	}

	// Parses given byte array and returns a Packet object
	public static Packet parse(byte[] buf, int off, int len)
			throws JimmException
	{

		// Check length (min. 6 bytes)
//#sijapp cond.if (target!="DEFAULT")&(modules_FILES="true")#
		if (len < 2)
//#sijapp cond.else#
//#		if (len < 6)
//#sijapp cond.end#		    
		{
			throw (new JimmException(130, 0));
		}

		// Verify FLAP.ID
		if (Util.getByte(buf, off) != 0x2A)
		{
//#sijapp cond.if (target!="DEFAULT")&(modules_FILES="true")#
			return (DCPacket.parse(buf, off, len));
//#sijapp cond.else#
//#			throw (new JimmException(130, 1));
//#sijapp cond.end#
		}

		// Get and verify FLAP.CHANNEL
		int channel = Util.getByte(buf, off + 1);
		if ((channel < 1) || (channel > 5))
		{
			throw (new JimmException(130, 2));
		}

		// Verify FLAP.LENGTH
		int length = Util.getWord(buf, off + 4);
		if ((length + 6) != len)
		{
			throw (new JimmException(130, 3));
		}

		// Parsing is done by a subclass
		switch (channel)
		{
		case Packet.CHANNEL_CONNECT:
			return (ConnectPacket.parse(buf, off, len));
		case Packet.CHANNEL_SNAC:
			return (SnacPacket.parse(buf, off, len));
		case Packet.CHANNEL_DISCONNECT:
			return (DisconnectPacket.parse(buf, off, len));
		default:
			return null;
		}

	}

	// Parses given byte array and returns a Packet object
	public static Packet parse(byte[] buf) throws JimmException
	{
		return (Packet.parse(buf, 0, buf.length));
	}

}