mappedresponsechangedsourceaddressreflectedfrom.java

解决了nat穿越的问题

/*
 * This file is part of JSTUN. 
 * 
 * Copyright (c) 2005 Thomas King <[e-mail]> - All rights
 * reserved.
 * 
 * This software is licensed under either the GNU Public License (GPL),
 * or the Apache 2.0 license. Copies of both license agreements are
 * included in this distribution.
 */

package de.javawi.jstun.attribute;

import de.javawi.jstun.util.*;

public class MappedResponseChangedSourceAddressReflectedFrom extends MessageAttribute {
	int port;
	Address address;
	
	/*  
	 *  0                   1                   2                   3
	 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	 * |x x x x x x x x|    Family     |           Port                |
	 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	 * |                             Address                           |
	 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	 */
	public MappedResponseChangedSourceAddressReflectedFrom() {
		super();
		try {
			port = 0;
			address = new Address("0.0.0.0");
		} catch (UtilityException ue) {
			ue.getMessage();
			ue.printStackTrace();
		}
	}
	
	public MappedResponseChangedSourceAddressReflectedFrom(MessageAttribute.MessageAttributeType type) {
		super(type);
	}
	
	public int getPort() {
		return port;
	}
	
	public Address getAddress() {
		return address;
	}
	
	public void setPort(int port) throws MessageAttributeException {
		if ((port > 65536) || (port < 0)) {
			throw new MessageAttributeException("Port value " + port + " out of range.");
		}
		this.port = port;
	}
	
	public void setAddress(Address address) {
		this.address = address;
	}
	
	public byte[] getBytes() throws UtilityException {
		byte[] result = new byte[12];
		// message attribute header
		// type
		System.arraycopy(Utility.IntegerToTwoBytes(typeToInteger(type)), 0, result, 0, 2);
		// length
		System.arraycopy(Utility.IntegerToTwoBytes(8), 0, result, 2, 2);
		
		// mappedaddress header
		// family
		result[5] = Utility.IntegerToOneByte(0x01); 
		// port
		System.arraycopy(Utility.IntegerToTwoBytes(port), 0, result, 6, 2);
		// address
		System.arraycopy(address.getBytes(), 0, result, 8, 4);
		return result;
	}
	
	protected static MappedResponseChangedSourceAddressReflectedFrom parse(MappedResponseChangedSourceAddressReflectedFrom ma, byte[] data) throws MessageAttributeParsingException {
		try {
			if (data.length < 8) {
				throw new MessageAttributeParsingException("Data array too short");
			}
			int family = Utility.OneByteToInteger(data[1]);
			if (family != 0x01) throw new MessageAttributeParsingException("Family " + family + " is not supported");
			byte[] portArray = new byte[2];
			System.arraycopy(data, 2, portArray, 0, 2);
			ma.setPort(Utility.TwoBytesToInteger(portArray));
			int firstOctet = Utility.OneByteToInteger(data[4]);
			int secondOctet = Utility.OneByteToInteger(data[5]);
			int thirdOctet = Utility.OneByteToInteger(data[6]);
			int fourthOctet = Utility.OneByteToInteger(data[7]);
			ma.setAddress(new Address(firstOctet, secondOctet, thirdOctet, fourthOctet));
			return ma;
		} catch (UtilityException ue) {
			throw new MessageAttributeParsingException("Parsing error");
		} catch (MessageAttributeException mae) {
			throw new MessageAttributeParsingException("Port parsing error");
		}
	}
	
	public String toString() {
		return "Address " +address.toString() + ", Port " + port;
	}
}