/*
 * $Id$
 *
 * 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.ethernet;

import org.jnode.net.HardwareAddress;
import org.jnode.net.LinkLayerHeader;
import org.jnode.net.SocketBuffer;

/**
 * Wrapper class for the IEEE 802.3 header.
 *  
 * @author epr
 */
public class EthernetHeader implements LinkLayerHeader, EthernetConstants {

    private final EthernetAddress destination;
    private final EthernetAddress source;
    private final int lengthType;

    /**
     * Create a new instance
     * @param destination
     * @param source
     * @param lengthType
     */
    public EthernetHeader(
            EthernetAddress destination,
            EthernetAddress source,
            int lengthType) {
        this.destination = destination;
        this.source = source;
        this.lengthType = lengthType;
    }

    /**
     * Create a new instance
     * @param skbuf
     */
    public EthernetHeader(SocketBuffer skbuf) {
        this.destination = new EthernetAddress(skbuf, 0);
        this.source = new EthernetAddress(skbuf, 6);
        this.lengthType = skbuf.get16(12);
    }

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

    /**
     * Prefix this header to the front of the given buffer
     * @param skbuf
     */
    public void prefixTo(SocketBuffer skbuf) {
        skbuf.insert(ETH_HLEN);
        destination.writeTo(skbuf, 0);
        source.writeTo(skbuf, 6);
        skbuf.set16(12, lengthType);
    }

    /**
     * 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 HardwareAddress getSourceAddress() {
        return source;
    }

    /**
     * Gets the source address of the packet described in this header 
     */
    public HardwareAddress getDestinationAddress() {
        return destination;
    }

    /**
     * Gets the destination address
     */
    public EthernetAddress getDestination() {
        return destination;
    }

    /**
     * Gets the length/type field
     */
    public int getLengthType() {
        return lengthType;
    }

    /**
     * Gets the source address
     */
    public EthernetAddress getSource() {
        return source;
    }

}