asndecoderv1.java

snmp zip 包开发snmp协议

// NAME
//      $RCSfile: AsnDecoderv1.java,v $
// DESCRIPTION
//      [given below in javadoc format]
// DELTA
//      $Revision: 3.3 $
// CREATED
//      $Date: 2006/02/09 14:16:36 $
// COPYRIGHT
//      Westhawk Ltd
// TO DO
//


/*
 * 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 v1 specific 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: 2006/02/09 14:16:36 $
 */
class AsnDecoderv1 extends AsnDecoderBase 
{
    private static final String     version_id =
        "@(#)$Id: AsnDecoderv1.java,v 3.3 2006/02/09 14:16:36 birgit Exp $ Copyright Westhawk Ltd";


/**
 * This method creates an AsnPduSequence or an AsnTrapPduv1Sequence out of 
 * the characters of the InputStream for v1.
 *
 * @see AbstractSnmpContext#run
 * @see SnmpContext#processIncomingResponse
 * @see SnmpContext#processIncomingPdu
 */
AsnSequence DecodeSNMP(InputStream in, String community)
throws IOException, DecodingException
{
    AsnSequence asnTopSeq = getAsnSequence(in);
    int snmpVersion = getSNMPVersion(asnTopSeq);
    if (snmpVersion != SnmpConstants.SNMP_VERSION_1)
    {
        String str = SnmpUtilities.getSnmpVersionString(snmpVersion);
        String msg = "Wrong SNMP version: expected SNMPv1, received "
            + str;
        throw new DecodingException(msg);
    }
    String comm = getCommunity(asnTopSeq);
    if (comm.equals(community) == false)
    {
        String msg = "Wrong community: expected "
            + community + ", received " + comm;
        throw new DecodingException(msg);
    }

    // The message is either a 'normal' PDU or a Trap v1 PDU.
    AsnSequence seqPdu = null;
    seqPdu = (AsnPduSequence) asnTopSeq.findPdu();
    if (seqPdu == null)
    {
        seqPdu = (AsnTrapPduv1Sequence) asnTopSeq.findTrapPduv1();
    }
    return seqPdu;
}




}