arpheader.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 218 行

/*
 * $Id: ARPHeader.java,v 1.1 2003/11/25 11:52:26 epr Exp $
 */
package org.jnode.net.arp;

import java.net.SocketException;

import org.jnode.net.HardwareAddress;
import org.jnode.net.NetworkLayerHeader;
import org.jnode.net.ProtocolAddress;
import org.jnode.net.SocketBuffer;
import org.jnode.net.ethernet.EthernetAddress;
import org.jnode.net.ethernet.EthernetConstants;
import org.jnode.net.ipv4.IPv4Address;

/**
 * @author epr
 */
public class ARPHeader implements NetworkLayerHeader {
	
	private HardwareAddress srcHWAddress;
	private ProtocolAddress srcPAddress;
	private HardwareAddress targetHWAddress;
	private ProtocolAddress targetPAddress;
	private int op;
	private final int hwtype;
	private final int ptype;

	/**
	 * Create a new instance
	 * @param srcHWAddress
	 * @param srcPAddress
	 * @param targetHWAddress
	 * @param targetPAddress
	 * @param op
	 * @param hwtype
	 * @param ptype
	 */
	public ARPHeader(
		HardwareAddress srcHWAddress,
		ProtocolAddress srcPAddress,
		HardwareAddress targetHWAddress,
		ProtocolAddress targetPAddress,
		int op,
		int hwtype,
		int ptype) {
			
		this.srcHWAddress = srcHWAddress;
		this.srcPAddress = srcPAddress;
		this.targetHWAddress = targetHWAddress;
		this.targetPAddress = targetPAddress;
		this.op = op;
		this.hwtype = hwtype;
		this.ptype = ptype;
	}
	
	/**
	 * Create a new packet from a socketbuffer
	 * @param skbuf
	 */
	public ARPHeader(SocketBuffer skbuf) 
	throws SocketException {
		hwtype = skbuf.get16(0);
		ptype = skbuf.get16(2);
		//int hwsize = skbuf.get(4);
		//int psize = skbuf.get(5);
		op = skbuf.get16(6);
		if ((hwtype == 1) && (ptype == EthernetConstants.ETH_P_IP)) {
			srcHWAddress = new EthernetAddress(skbuf, 8);
			srcPAddress = new IPv4Address(skbuf, 14);
			targetHWAddress = new EthernetAddress(skbuf, 18);
			targetPAddress = new IPv4Address(skbuf, 24);
		} else {
			throw new SocketException("Unknown hw,ptype: " + hwtype + "," + ptype);
		}
	}

	/**
	 * Gets the length of this header in bytes
	 */
	public int getLength() {
		return (8 + (srcHWAddress.getLength() + srcPAddress.getLength()) * 2);
	}
	
	/**
	 * Write this packet to the given buffer
	 * @param skbuf
	 */
	public void prefixTo(SocketBuffer skbuf) {
		skbuf.insert(8 + (srcHWAddress.getLength() + srcPAddress.getLength()) * 2);
		int ofs = 0;
		skbuf.set16(ofs+0, hwtype);
		skbuf.set16(ofs+2, ptype);
		skbuf.set(ofs+4, srcHWAddress.getLength());
		skbuf.set(ofs+5, srcPAddress.getLength());
		skbuf.set16(ofs+6, op);
		ofs += 8;
		srcHWAddress.writeTo(skbuf, ofs);
		ofs += srcHWAddress.getLength();
		srcPAddress.writeTo(skbuf, ofs);
		ofs += srcPAddress.getLength();
		targetHWAddress.writeTo(skbuf, ofs);
		ofs += targetHWAddress.getLength();
		targetPAddress.writeTo(skbuf, ofs);
	}
	
	
	/**
	 * Finalize the header in the given buffer.
	 * This method is called when all layers have set their header data
	 * and can be used e.g. to update checksum values.
	 * 
	 * @param skbuf The buffer
	 * @param offset The offset to the first byte (in the buffer) of this header (since low layer headers are already prefixed)
	 */
	public void finalizeHeader(SocketBuffer skbuf, int offset) {
		// Do nothing
	}
	
	/**
	 * Gets the source address of the packet described in this header 
	 */
	public ProtocolAddress getSourceAddress() {
		return srcPAddress;
	}

	/**
	 * Gets the source address of the packet described in this header 
	 */
	public ProtocolAddress getDestinationAddress() {
		return targetPAddress;	
	}
	
	/**
	 * Gets the hardware type
	 */
	public int getHType() {
		return hwtype;
	}

	/**
	 * Gets the operation
	 */
	public int getOperation() {
		return op;
	}

	/**
	 * Gets the protocol type
	 */
	public int getPType() {
		return ptype;
	}

	/**
	 * Gets the source hardware address
	 */
	public HardwareAddress getSrcHWAddress() {
		return srcHWAddress;
	}

	/**
	 * Gets the source protocol address
	 */
	public ProtocolAddress getSrcPAddress() {
		return srcPAddress;
	}

	/**
	 * Gets the target hardware address
	 */
	public HardwareAddress getTargetHWAddress() {
		return targetHWAddress;
	}

	/**
	 * Gets the target protocol address
	 */
	public ProtocolAddress getTargetPAddress() {
		return targetPAddress;
	}
	
	/**
	 * Swap the two src and target addresses
	 *
	 */
	public void swapAddresses() {
		final HardwareAddress hwTmp = targetHWAddress;
		final ProtocolAddress pTmp = targetPAddress;
		targetHWAddress = srcHWAddress;
		targetPAddress = srcPAddress;
		srcHWAddress = hwTmp;
		srcPAddress = pTmp;
	}
	
	/**
	 * @param i
	 */
	public void setOperation(int i) {
		op = i;
	}
	
	/**
	 * @param address
	 */
	public void setSrcHWAddress(HardwareAddress address) {
		srcHWAddress = address;
	}

	/**
	 * @param address
	 */
	public void setSrcPAddress(ProtocolAddress address) {
		srcPAddress = address;
	}

}