icmpprotocol.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 231 行

/*
 * $Id: ICMPProtocol.java,v 1.1 2003/11/25 11:52:20 epr Exp $
 */
package org.jnode.net.ipv4.icmp;

import java.net.DatagramSocketImplFactory;
import java.net.SocketException;
import java.net.SocketImplFactory;

import org.apache.log4j.Logger;
import org.jnode.net.SocketBuffer;
import org.jnode.net.ipv4.IPv4Constants;
import org.jnode.net.ipv4.IPv4Header;
import org.jnode.net.ipv4.IPv4Protocol;
import org.jnode.net.ipv4.IPv4Service;
import org.jnode.util.Queue;
import org.jnode.util.QueueProcessor;
import org.jnode.util.QueueProcessorThread;
import org.jnode.util.Statistics;

/**
 * Protocol handler of the ICMP protocol.
 * 
 * @author Ewout Prangsma ([e-mail])
 */
public class ICMPProtocol implements IPv4Protocol, IPv4Constants, ICMPConstants, QueueProcessor {

	/** My logger */
	private Logger log = Logger.getLogger(getClass());
	/** The IP service we're a part of */
	private final IPv4Service ipService;
	/** The statistics */
	private final ICMPStatistics stat = new ICMPStatistics();
	/** Queue<SocketBuffer> for requests that need a reply */
	private final Queue replyRequestQueue = new Queue();
	private final QueueProcessorThread replyRequestsThread;
	
	/**
	 * Create a new instance
	 * @param ipService
	 */
	public ICMPProtocol(IPv4Service ipService) {
		this.ipService = ipService;
		this.replyRequestsThread = new QueueProcessorThread("icmp-reply", replyRequestQueue, this);
		replyRequestsThread.start();
	}
	
	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#getName()
	 */
	public String getName() {
		return "icmp";
	}

	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#getProtocolID()
	 */
	public int getProtocolID() {
		return IPPROTO_ICMP;
	}

	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#receive(org.jnode.net.SocketBuffer)
	 */
	public void receive(SocketBuffer skbuf) throws SocketException {
		
		// Update statistics
		stat.ipackets.inc();
		
		final ICMPHeader hdr = createHeader(skbuf);
		skbuf.setTransportLayerHeader(hdr);
		skbuf.pull(hdr.getLength());
		
		if (!hdr.isChecksumOk()) {
			stat.badsum.inc();
			return;
		} 
		
		// TODO Process ICMP messages

		switch (hdr.getType()) {
			case ICMP_ECHO: 
				postReplyRequest(skbuf);
				break;		 

			default:
				log.debug("GOT ICMP type " + hdr.getType() + ", code " + hdr.getCode());			
		}
	}
	
	/**
	 * Process an ICMP error message that has been received and matches
	 * this protocol. 
	 * The skbuf is position directly after the ICMP header (thus contains
	 * the error IP header and error transport layer header).
	 * The transportLayerHeader property of skbuf is set to the 
	 * ICMP message header.
	 * 
	 * @param skbuf
	 * @throws SocketException
	 */
	public void receiveError(SocketBuffer skbuf)
	throws SocketException {
		// Ignore errors here
	}
		
	/**
	 * Gets the SocketImplFactory of this protocol.
	 * @throws SocketException If this protocol is not Socket based.
	 */
	public SocketImplFactory getSocketImplFactory()
	throws SocketException {
		throw new SocketException("ICMP is packet based");
	}

	/**
	 * Gets the DatagramSocketImplFactory of this protocol.
	 * @throws SocketException If this protocol is not DatagramSocket based.
	 */
	public DatagramSocketImplFactory getDatagramSocketImplFactory()
	throws SocketException {
		throw new SocketException("Not implemented yet");
	}

	/**
	 * Send an ICMP packet
	 * @param skbuf
	 */
	protected void send(IPv4Header ipHdr, ICMPHeader icmpHdr, SocketBuffer skbuf) 
	throws SocketException {
		//Syslog.debug("ICMP.send");
		stat.opackets.inc();
		skbuf.setTransportLayerHeader(icmpHdr);
		icmpHdr.prefixTo(skbuf);
		ipService.transmit(ipHdr, skbuf);
	}
	
	/**
	 * Send a reply on an ICMP echo header.
	 * @param hdr
	 * @param skbuf
	 */
	private void sendEchoReply(ICMPEchoHeader hdr, SocketBuffer skbuf) 
	throws SocketException {
		final IPv4Header ipHdr = (IPv4Header)skbuf.getNetworkLayerHeader();
		final IPv4Header ipReplyHdr = new IPv4Header(ipHdr);
		ipReplyHdr.swapAddresses();
		ipReplyHdr.setTtl(0xFF);
		send(ipReplyHdr, hdr.createReplyHeader(), new SocketBuffer(skbuf));
	}
	
	/**
	 * Create a type specific ICMP header. The type is read from the first
	 * first in the skbuf.
	 * @param skbuf
	 * @throws SocketException
	 */
	private ICMPHeader createHeader(SocketBuffer skbuf) 
	throws SocketException {
		final int type = skbuf.get(0);
		switch (type) {
			case ICMP_DEST_UNREACH: 
				return new ICMPUnreachableHeader(skbuf);

			case ICMP_TIMESTAMP:
			case ICMP_TIMESTAMPREPLY:
				return new ICMPTimestampHeader(skbuf);
				
			case ICMP_ADDRESS:
			case ICMP_ADDRESSREPLY:
				return new ICMPAddressMaskHeader(skbuf);

			case ICMP_ECHOREPLY:
			case ICMP_ECHO:		
				return new ICMPEchoHeader(skbuf);
				 
			case ICMP_SOURCE_QUENCH:
			case ICMP_REDIRECT:
			case ICMP_TIME_EXCEEDED:
			case ICMP_PARAMETERPROB:
			case ICMP_INFO_REQUEST:
			case ICMP_INFO_REPLY:
				throw new SocketException("Not implemented");
			default:
				throw new SocketException("Unknown ICMP type " + type);				
		}
	}
	
	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#getStatistics()
	 */
	public Statistics getStatistics() {
		return stat;
	}

	/**
	 * Post a request that needs a reply in the reply queue.
	 * @param skbuf
	 */
	private void postReplyRequest(SocketBuffer skbuf) {
		replyRequestQueue.add(skbuf);
	}
	
	/**
	 * Process a request that needs a reply
	 * @param skbuf
	 */
	private void processReplyRequest(SocketBuffer skbuf) {
		final ICMPHeader hdr = (ICMPHeader)skbuf.getTransportLayerHeader();
		try {
			switch (hdr.getType()) {
				case ICMP_ECHO: 
					//Syslog.debug("<Send reply>");
					sendEchoReply((ICMPEchoHeader)hdr, skbuf); 
					//Syslog.debug("</Send reply>");
					break;		 
			}
		} catch (SocketException ex) {
			log.debug("Error in ICMP reply", ex);
		}
	}
	
	/**
	 * @see org.jnode.util.QueueProcessor#process(java.lang.Object)
	 */
	public void process(Object object) throws Exception {
		processReplyRequest((SocketBuffer)object);
	}

}