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/*
 * The MIT License (MIT)
 * 
 * Copyright (c) 2015-2016 Bertrand Martel
 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 

 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package fr.bmartel.pcapdecoder.structure.options;

import java.util.Arrays;

import fr.bmartel.pcapdecoder.structure.BlockTypes;
import fr.bmartel.pcapdecoder.structure.options.inter.IOptions;
import fr.bmartel.pcapdecoder.structure.options.object.OptionEnhancedPacketHeaderObject;
import fr.bmartel.pcapdecoder.structure.options.object.OptionInterfaceDescriptionObject;
import fr.bmartel.pcapdecoder.structure.options.object.OptionInterfaceStatisticsObject;
import fr.bmartel.pcapdecoder.structure.options.object.OptionSectionHeaderObject;
import fr.bmartel.pcapdecoder.structure.options.object.OptionsNameResolutionObject;
import fr.bmartel.pcapdecoder.structure.options.object.OptionsRecordNameResolutionObject;
import fr.bmartel.pcapdecoder.utils.UtilFunctions;

/**
 * Pcap NG option parser
 * 

 * => this is needed for several options can be present in the same section
 * 
 * 0                   1                   2                   3
 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |      Option Code              |         Option Length         |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * /                       Option Value                            /
 * /            variable length, aligned to 32 bits               /
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * /                                                               /
 * /                 . . . other options . . .                     /
 * /                                                               /
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |   Option Code == opt_endofopt  |  Option Length == 0          |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * @author Bertrand Martel
 */
public class OptionParser {

    /**
     * option data
     */
    private byte[] data = null;

    /**
     * type of section (option validation depends on block section type)
     */
    private BlockTypes type = null;

    /**
     * define if data is in big endian or little endian
     */
    private boolean isBigEndian = true;

    private IOptions option = null;

    private boolean isRecord = false;

    /**
     * Build parser with data
     *
     * @param data
     * @param isBigEndian
     * @BlockTypes type
     */
    public OptionParser(byte[] data, boolean isBigEndian, BlockTypes type, boolean isRecord) {
        this.data = data;
        this.isBigEndian = isBigEndian;
        this.type = type;
        this.isRecord = isRecord;
    }

    /**
     * decode data option
     */
    public int decode() {
        int initIndex = 0;

        if (type == BlockTypes.SECTION_HEADER_BLOCK) {
            option = new OptionSectionHeaderObject();
        } else if (type == BlockTypes.INTERFACE_DESCRIPTION_BLOCK) {
            option = new OptionInterfaceDescriptionObject();
        } else if (type == BlockTypes.ENHANCES_PACKET_BLOCK) {
            option = new OptionEnhancedPacketHeaderObject();
        } else if (type == BlockTypes.INTERFACE_STATISTICS_BLOCK) {
            option = new OptionInterfaceStatisticsObject();
        } else if (type == BlockTypes.NAME_RESOLUTION_BLOCK) {
            if (isRecord)
                option = new OptionsRecordNameResolutionObject();
            else {
                option = new OptionsNameResolutionObject();
            }
        }

        int optionLength = -1;

        while (optionLength != 0) {
            int optionCode = 0;
            optionLength = 0;
            byte[] optionValue = null;

            if (isBigEndian) {
                optionCode = UtilFunctions.convertByteArrayToInt(Arrays.copyOfRange(data, initIndex + 0, initIndex +
                        2));
                if (optionCode == 0) {
                    initIndex += 2;
                    return initIndex;
                }

                optionLength = UtilFunctions.convertByteArrayToInt(Arrays.copyOfRange(data, initIndex + 2, initIndex
						+ 4));
                if (optionLength > 0) {
                    optionValue = Arrays.copyOfRange(data, initIndex + 4, initIndex + 4 + optionLength);
                }
            } else {
                optionCode = UtilFunctions.convertByteArrayToInt(UtilFunctions.convertLeToBe(Arrays.copyOfRange(data,
						initIndex + 0, initIndex + 2)));
                if (optionCode == 0) {
                    initIndex += 2;
                    return initIndex;
                }
                optionLength = UtilFunctions.convertByteArrayToInt(UtilFunctions.convertLeToBe(Arrays.copyOfRange
						(data, initIndex + 2, initIndex + 4)));
                if (optionLength > 0) {
                    optionValue = UtilFunctions.convertLeToBe(Arrays.copyOfRange(data, initIndex + 4, initIndex + 4 +
							optionLength));
                }
            }

            if (optionLength == 0) {
                initIndex += 2;
            } else {
                PcapOptions optionParser = new PcapOptions(optionCode, optionLength, optionValue, isBigEndian, type, option);
                optionParser.decode();

                initIndex += 4 + optionLength;
            }

            initIndex = initIndex + (optionLength % 2);

            int endOfOption = UtilFunctions.convertByteArrayToInt(UtilFunctions.convertLeToBe(Arrays.copyOfRange(data, initIndex + 0, initIndex + 2)));


            if (endOfOption == 0) {
                initIndex += 2;
            }
        }
        return initIndex;
    }

    public byte[] getData() {
        return data;
    }

    public boolean isBigEndian() {
        return isBigEndian;
    }

    public BlockTypes getType() {
        return type;
    }

    public IOptions getOption() {
        return option;
    }
}