org.ambud.marauder.source.ids.pcap.layer2.EtherFrame.java Source code

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Here is the source code for org.ambud.marauder.source.ids.pcap.layer2.EtherFrame.java

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/*
 * Copyright 2013 Ambud Sharma
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.2
 */
package org.ambud.marauder.source.ids.pcap.layer2;

import java.io.DataInput;
import java.io.IOException;

import org.ambud.marauder.source.ids.pcap.layer3.ARP;
import org.ambud.marauder.source.ids.pcap.layer3.IPv4;
import org.ambud.marauder.source.ids.pcap.layer3.IPv6;
import org.ambud.marauder.source.ids.pcap.layer3.NetworkLayer;
import org.apache.commons.codec.binary.Hex;

public class EtherFrame {

    public static final int ETHER_HDR_SIZE = 6 + 6 + 2;
    public static final int ETHER_HDR_VLAN_SIZE = 6 + 6 + 4 + 2;
    public static final int ETHER_CRC_SIZE = 4;

    public static final int ETHER_ADDR_SIZE = 6;

    private byte[] dstMac = new byte[ETHER_ADDR_SIZE], srcMac = new byte[ETHER_ADDR_SIZE];
    private FRAME_TYPE frameType;

    private short frameTyp;
    private int packetTimestamp;

    public short getFrameTyp() {
        return frameTyp;
    }

    // VLAN fields start
    // for VLAN / 802.1Q packets only   
    private byte priority, cfi;
    private short vlanID = -1;
    // VLAN fields end   

    private NetworkLayer networkLayer;

    public EtherFrame(int packetTimestamp) {
        this.packetTimestamp = packetTimestamp;
    }

    public void decode(DataInput di) throws IOException {
        di.readFully(this.dstMac);
        di.readFully(this.srcMac);
        this.frameTyp = extractTagType(di);
        //Data follows here
        readNetworkLayer(di);
    }

    protected short extractTagType(DataInput di) throws IOException {
        short frameType = readShort(di);
        switch (frameType) {
        case (short) 0x8100: // VLAN tagged packet (most likely for an enterprise network)
            this.frameType = FRAME_TYPE.VLAN;
            short temp = readShort(di); //read the rest 2 bytes of the 802.1Q tag field
            this.priority = (byte) ((temp >> 13) & 0xff);
            this.cfi = (byte) (((temp << 3) >> 15) & 0xff);
            this.vlanID = (short) (((temp << 4) >> 4) & 0xff);
            extractTagType(di); // recurse to extract type/length info
            break;
        case 0x0800: // regular IP packet
            this.frameType = FRAME_TYPE.IPv4;
            break;
        case 0x0806: // ARP
            this.frameType = FRAME_TYPE.ARP;
            break;
        case (short) 0x86dd: // Ipv6
            this.frameType = FRAME_TYPE.IPv6;
            break;
        case (short) 0x8137: // IPeX (Novell)
            break;
        default: // 0-1500 denotes length
            this.frameType = FRAME_TYPE.LENGTH;
        }
        return frameType;
    }

    protected void readNetworkLayer(DataInput di) throws IOException {
        switch (frameType) {
        case IPv4:
            networkLayer = new IPv4();
            break;
        case IPv6:
            networkLayer = new IPv6();
            break;
        case ARP:
            networkLayer = new ARP();
            break;
        case LENGTH: //802.3 packet
        case VLAN: // unsupported packet
        default:
        }
        if (networkLayer != null) {
            networkLayer.decode(di, this);
        }
    }

    /**
     * @return the dstMac
     */
    public byte[] getDstMac() {
        return dstMac;
    }

    /**
     * @return the srcMac
     */
    public byte[] getSrcMac() {
        return srcMac;
    }

    /**
     * @return the frameType
     */
    public FRAME_TYPE getFrameType() {
        return frameType;
    }

    /**
     * @return the priority
     */
    public byte getPriority() {
        return priority;
    }

    /**
     * @return the cfi
     */
    public byte getCfi() {
        return cfi;
    }

    /**
     * @return the vlanID
     */
    public short getVlanID() {
        return vlanID;
    }

    /**
     * @return the nextLayer
     */
    public NetworkLayer getNetworkLayer() {
        return networkLayer;
    }

    @Override
    public String toString() {
        return "DstAddr:" + Hex.encodeHexString(dstMac) + " SrcAddr:" + Hex.encodeHexString(srcMac) + " FrameType:"
                + frameType.name() + " vlan:" + vlanID;
    }

    /**
     * @return the packetTimestamp
     */
    public int getPacketTimestamp() {
        return packetTimestamp;
    }

    /**
     * Had to Re-define/override because of errors with LittleEndianInputStream 
     * @param di
     * @return short
     * @throws IOException
     */
    public static short readShort(DataInput di) throws IOException {
        byte[] temp = new byte[2];
        di.readFully(temp);
        return (short) ((temp[0] << 8) | temp[1] & 0xff);
    }

    public static enum FRAME_TYPE {
        LENGTH, VLAN, IPv4, IPv6, ARP;
    }

}