org.ambud.marauder.source.ids.pcap.LibpcapGlobalHeader.java Source code

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Here is the source code for org.ambud.marauder.source.ids.pcap.LibpcapGlobalHeader.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;

import java.io.DataInput;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;

import com.google.common.io.LittleEndianDataInputStream;

/**
 * Object representation of libpcap file header.
 * 
 * Format source: Wireshark documentation
 * 
 * This format is v2.4 as of 9/4/2013
 * 
 * @author Ambud Sharma
 */
public class LibpcapGlobalHeader {

    // http://wiki.wireshark.org/Development/LibpcapFileFormat
    private int magicNumber; /* magic number (unsigned long32) */
    private int versionMajor, /* major version number (unsigned long16) */
            versionMinor; /* minor version number (unsigned long16) */
    private int thisZone; /* GMT to local correction (signed long32) */
    private int sigFigs, /* accuracy of timestamps (unsigned long32) */
            snaplen, /*
                      * max length of captured packets, in octets (unsigned
                      * long32)
                      */
            network; /* data link type (unsigned long32) */
    private boolean isSwapped; /*
                               * computed from magic number and check endianess
                               * of the file-data
                               */

    public LibpcapGlobalHeader(InputStream inputStream) throws IOException {
        this.magicNumber |= inputStream.read() << 24;
        this.magicNumber |= inputStream.read() << 16;
        this.magicNumber |= inputStream.read() << 8;
        this.magicNumber |= inputStream.read();
        this.isSwapped = (this.magicNumber == 0xd4c3b2a1) ? true : false;
        DataInput temp = null;
        if (isSwapped) {
            temp = new LittleEndianDataInputStream(inputStream);
            this.versionMajor = temp.readUnsignedShort();
            this.versionMinor = temp.readUnsignedShort();
            this.thisZone = temp.readInt();
            this.sigFigs = temp.readInt();
            this.snaplen = temp.readInt();
            this.network = temp.readInt();
        } else {
            temp = new DataInputStream(inputStream);
            this.versionMajor = temp.readUnsignedShort();
            this.versionMinor = temp.readUnsignedShort();
            this.thisZone = temp.readInt();
            this.sigFigs = temp.readInt();
            this.snaplen = temp.readInt();
            this.network = temp.readInt();
        }
    }

    /**
     * @return the isSwapped
     */
    protected boolean isSwapped() {
        return isSwapped;
    }

    /**
     * @return the magicNumber
     */
    protected int getMagicNumber() {
        return magicNumber;
    }

    /**
     * @return the versionMajor
     */
    protected int getVersionMajor() {
        return versionMajor;
    }

    /**
     * @return the versionMinor
     */
    protected int getVersionMinor() {
        return versionMinor;
    }

    /**
     * @return the thisZone
     */
    protected int getThisZone() {
        return thisZone;
    }

    /**
     * @return the sigFigs
     */
    protected int getSigFigs() {
        return sigFigs;
    }

    /**
     * @return the snaplen
     */
    protected int getSnaplen() {
        return snaplen;
    }

    /**
     * @return the network
     */
    protected int getNetwork() {
        return network;
    }

    @Override
    public String toString() {
        return "Magic Number:" + Integer.toHexString(magicNumber) + " isSwapped:" + isSwapped + " Major_V:"
                + versionMajor + " Minor_V:" + versionMinor + " Zone:" + thisZone + " Time Resolution:" + sigFigs
                + " Snap Length:" + snaplen + " Network Link Type:" + network;
    }

}