LayerHeader.java

/*
 * $Id$
 *
 * Copyright (C) 2003-2015 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;

/**
 * Headers of a any OSI layer must implement this interface.
 * 
 * @author epr
 * @see org.jnode.net.LinkLayerHeader
 * @see org.jnode.net.NetworkLayerHeader
 * @see org.jnode.net.TransportLayerHeader
 */
public interface LayerHeader {

    /**
     * Gets the length of this header in bytes
     */
    public int getLength();

    /**
     * Prefix this header to the front of the given buffer
     * 
     * @param skbuf
     */
    public void prefixTo(SocketBuffer skbuf);

    /**
     * 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);
}