udpprotocol.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 208 行

/*
 * $Id: UDPProtocol.java,v 1.2 2003/12/21 08:03:00 epr Exp $
 */
package org.jnode.net.ipv4.udp;

import java.io.IOException;
import java.net.DatagramSocket;
import java.net.DatagramSocketImplFactory;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.SocketImplFactory;
import java.util.HashMap;

import org.jnode.driver.net.NetworkException;
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.net.ipv4.icmp.ICMPUtils;
import org.jnode.util.Statistics;

/**
 * @author epr
 */
public class UDPProtocol implements IPv4Protocol, IPv4Constants {

	/** The underlying IP service */
	private final IPv4Service ipService;
	/** Socket bindings (lport, socket) */
	private final HashMap sockets = new HashMap();
	/** DatagramSocketImplFactor instance */
	private final UDPDatagramSocketImplFactory dsiFactory;
	/** My statistics */
	private final UDPStatistics stat = new UDPStatistics();
	/** ICMP utility */
	private final ICMPUtils icmp;

	/**
	 * Create a new instance
	 * @param ipService
	 */
	public UDPProtocol(IPv4Service ipService) 
	throws NetworkException {
		this.ipService = ipService;
		this.icmp = new ICMPUtils(ipService);
		try {
			dsiFactory = new UDPDatagramSocketImplFactory(this);
			DatagramSocket.setSystemDatagramSocketImplFactory(dsiFactory);
		} catch (IOException ex) {
			throw new NetworkException(ex);
		}
	}

	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#getName()
	 */
	public String getName() {
		return "udp";
	}

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

	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#receive(org.jnode.net.SocketBuffer)
	 */
	public void receive(SocketBuffer skbuf) 
	throws SocketException {
		
		stat.ipackets.inc();
		
		final UDPHeader hdr = new UDPHeader(skbuf);
		if (!hdr.isChecksumOk()) {
			stat.badsum.inc();
			//Syslog.debug("Ignoring invalid UDP packet (" + hdr + "), invalid checksum");
			return;
		}
		
		// Set the UDP header in the buffer-field		
		skbuf.setTransportLayerHeader(hdr);
		// Remove the UDP header from the head of the buffer
		skbuf.pull(hdr.getLength());
		// Trim the buffer up to the length in the UDP header
		skbuf.trim(hdr.getDataLength());
		
		// Test the length of the buffer to the datalength in the header.
		if (skbuf.getSize() < hdr.getDataLength()) {
			stat.badlen.inc();
			//Syslog.debug("Ignored UDP packet, mismatch between datalength and buffersize");
			return;			
		}
		
		//Syslog.debug("Found UDP: " + hdr);
		
		deliver(hdr, skbuf);
	}
	

	/**
	 * 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 {
		// TODO handle ICMP errors in UDP
	}
		
	/**
	 * Gets the SocketImplFactory of this protocol.
	 * @throws SocketException If this protocol is not Socket based.
	 */
	public SocketImplFactory getSocketImplFactory()
	throws SocketException {
		throw new SocketException("UDP is packet based");
	}

	/**
	 * Gets the DatagramSocketImplFactory of this protocol.
	 */
	public DatagramSocketImplFactory getDatagramSocketImplFactory() {
		return dsiFactory;
	}
	
	/**
	 * Deliver a given packet to all interested sockets.
	 * @param hdr
	 * @param skbuf
	 */
	private synchronized void deliver(UDPHeader hdr, SocketBuffer skbuf) 
	throws SocketException {
		final Integer lport = new Integer(hdr.getDstPort());
		final IPv4Header ipHdr = (IPv4Header)skbuf.getNetworkLayerHeader();
		final UDPDatagramSocketImpl socket = (UDPDatagramSocketImpl)sockets.get(lport);
		if (socket != null) {
			final InetAddress laddr = socket.getLocalAddress();
			if (laddr.isAnyLocalAddress() || 
				laddr.equals(ipHdr.getDestination().toInetAddress())) {
				if (socket.deliverReceived(skbuf)) {
					return;
				}
			}
		}
		stat.noport.inc();
		if (ipHdr.getDestination().isBroadcast()) {
			stat.noportbcast.inc();
		}
		// Send a port unreachable back
		icmp.sendPortUnreachable(skbuf);
	}
	
	/**
	 * Register a datagram socket
	 * @param socket
	 */
	protected synchronized void bind(UDPDatagramSocketImpl socket) 
	throws SocketException {
		final Integer lport = new Integer(socket.getLocalPort());
		if (sockets.containsKey(lport)) {
			throw new SocketException("Port already bound (" + lport + ")");
		} else {
			sockets.put(lport, socket);
		}
	}
	
	/**
	 * Unregister a datagram socket
	 * @param socket
	 */
	protected synchronized void unbind(UDPDatagramSocketImpl socket) { 
		final Integer lport = new Integer(socket.getLocalPort());
		if (sockets.get(lport) == socket) {
			sockets.remove(lport);
		}
	}
	
	/**
	 * Send an UDP packet
	 * @param skbuf
	 */
	protected void send(IPv4Header ipHdr, UDPHeader udpHdr, SocketBuffer skbuf) 
	throws SocketException {
		//Syslog.debug("UDP.send");
		skbuf.setTransportLayerHeader(udpHdr);
		udpHdr.prefixTo(skbuf);
		ipService.transmit(ipHdr, skbuf);
		stat.opackets.inc();
	}
	
	/**
	 * @see org.jnode.net.ipv4.IPv4Protocol#getStatistics()
	 */
	public Statistics getStatistics() {
		return stat;
	}
}