asndecoderbase.java

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// NAME
//      $RCSfile: AsnDecoderBase.java,v $
// DESCRIPTION
//      [given below in javadoc format]
// DELTA
//      $Revision: 3.3 $
// CREATED
//      $Date: 2007/10/17 10:36:47 $
// COPYRIGHT
//      Westhawk Ltd
// TO DO
//

/*
 * Copyright (C) 1995, 1996 by West Consulting BV
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted, provided
 * that the above copyright notices appear in all copies and that
 * both the copyright notice and this permission notice appear in
 * supporting documentation.
 * This software is provided "as is" without express or implied
 * warranty.
 * author <a href="mailto:[e-mail]">Tim Panton</a>
 * original version by [e-mail] (Jordan Hargrave)
 */

/*
 * Copyright (C) 1996 - 2006 by Westhawk Ltd
 * <a href="www.westhawk.co.uk">www.westhawk.co.uk</a>
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted, provided
 * that the above copyright notices appear in all copies and that
 * both the copyright notice and this permission notice appear in
 * supporting documentation.
 * This software is provided "as is" without express or implied
 * warranty.
 * author <a href="mailto:[e-mail]">Tim Panton</a>
 */

package uk.co.westhawk.snmp.stack;

import uk.co.westhawk.snmp.util.*;
import java.io.*;
import java.util.*;

/**
 * This class contains the general methods to decode bytes into a Pdu.
 * We split the original class AsnDecoder into four classes.
 *
 * @since 4_14
 * @author <a href="mailto:[e-mail]">Tim Panton</a>
 * @version $Revision: 3.3 $ $Date: 2007/10/17 10:36:47 $
 */
class AsnDecoderBase extends Object 
{
    private static final String     version_id =
        "@(#)$Id: AsnDecoderBase.java,v 3.3 2007/10/17 10:36:47 birgita Exp $ Copyright Westhawk Ltd";

/**
 * Reads the input into an asn sequence.
 */
AsnSequence getAsnSequence(InputStream in)
throws IOException, DecodingException
{
    AsnSequence asnTopSeq = null;
    AsnSequence dummy = new AsnSequence();
    AsnObject obj = dummy.AsnReadHeader(in);
    if (obj instanceof AsnSequence)
    {
        asnTopSeq = (AsnSequence) obj;
    }
    else
    {
        String msg = "AsnSequence was expected";
        if (obj != null)
        {
            msg += " instead of " + obj.getRespTypeString();
        }
        else
        {
            msg += ", but is null";
        }
        throw new DecodingException(msg);
    }
    return asnTopSeq;
}

/**
 * Returns the SNMP version number of the asn sequence.
 */
int getSNMPVersion(AsnSequence asnTopSeq) throws DecodingException
{
    int version = -1;
    AsnObject obj = asnTopSeq.getObj(0);
    if (obj instanceof AsnInteger)
    {
        AsnInteger v = (AsnInteger) obj;
        version = v.getValue();
    }
    else
    {
        String msg = "SNMP version should be of type AsnInteger"
            + " instead of " + obj.getRespTypeString();
        throw new DecodingException(msg);
    }
    return version;
}

/**
 * Returns the SNMP v1 and v2c community of the asn sequence.
 */
String getCommunity(AsnSequence asnTopSeq) throws DecodingException
{
    String comm ="";
    AsnObject obj = asnTopSeq.getObj(1);
    if (obj instanceof AsnOctets)
    {
        AsnOctets estat = (AsnOctets) obj;
        comm = estat.getValue();
    }
    else
    {
        String msg = "community should be of type AsnOctets"
            + " instead of " + obj.getRespTypeString();
        throw new DecodingException(msg);
    }
    return comm;
}


AsnSequence getAsnHeaderData(AsnSequence asnTopSeq) throws DecodingException
{
    AsnSequence asnHeaderData = null;
    AsnObject obj = asnTopSeq.getObj(1);
    if (obj instanceof AsnSequence)
    {
        asnHeaderData = (AsnSequence) obj;
    }
    else
    {
        String msg = "asnHeaderData should be of type AsnSequence"
            + " instead of " + obj.getRespTypeString();
        throw new DecodingException(msg);
    }
    return asnHeaderData;
}



}