/*
* $Id$
*
* Copyright (C) 2003-2014 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.net.ipv4.icmp;
import java.net.SocketException;
import org.jnode.net.SocketBuffer;
import org.jnode.net.ipv4.IPv4Address;
import org.jnode.net.ipv4.IPv4Constants;
import org.jnode.net.ipv4.IPv4Header;
import org.jnode.net.ipv4.IPv4Service;
/**
* Utility class for other IP protocols, to allow them to call simple methods
* for generating ICMP messages.
*
* @author epr
*/
public class ICMPUtils {
private final IPv4Service ipService;
/**
* Create a new instance
*
* @param ipService
*/
public ICMPUtils(IPv4Service ipService) {
this.ipService = ipService;
}
/**
* Send an ICMP port unreachable message in response to the given buffer.
* The IP header and the Transport layer header must be set as attributes in
* srcBuf, and must be removed from the head of the buffer.
*
* @param srcBuf
*/
public void sendPortUnreachable(SocketBuffer srcBuf) throws SocketException {
sendUnreachable(srcBuf, 3);
}
/**
* Send an ICMP unreachable message in response to the given buffer. The IP
* header and the Transport layer header must be set as attributes in
* srcBuf, and must be removed from the head of the buffer.
*
* @param srcBuf
*/
private final void sendUnreachable(SocketBuffer srcBuf, int code) throws SocketException {
// Do not respond to linklayer broadcast messages
if (srcBuf.getLinkLayerHeader().getDestinationAddress().isBroadcast()) {
return;
}
// Gets the original IP header
final IPv4Header origIpHdr = (IPv4Header) srcBuf.getNetworkLayerHeader();
// Do not respond to networklayer broadcast/multicast messages
if (origIpHdr.getDestination().isBroadcast() || origIpHdr.getDestination().isMulticast()) {
return;
}
final int tos = 0;
final int ttl = 0xFF;
final IPv4Address dstAddr = origIpHdr.getSource();
// Build the response ICMP header
final ICMPHeader icmpHdr = new ICMPUnreachableHeader(code);
// Build the response IP header
final IPv4Header ipHdr = new IPv4Header(tos, ttl, IPv4Constants.IPPROTO_ICMP, dstAddr, 0);
// Unpull the original transportlayer header
srcBuf.unpull(srcBuf.getTransportLayerHeader().getLength());
// Unpull the original IP header
srcBuf.unpull(origIpHdr.getLength());
// Create a response buffer
final SocketBuffer skbuf = new SocketBuffer();
// Prefix the ICMP header to the response buffer
icmpHdr.prefixTo(skbuf);
// Append the original message to the response buffer
skbuf.append(srcBuf);
// / RFC says return as much as we can without exceeding 576 bytes.
skbuf.trim(576);
ipService.transmit(ipHdr, skbuf);
}
}