snmptrapsession.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2003 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// 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 2 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, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// For more information contact:
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
//
// Tab Size = 8
//
// SnmpTrapSession.java,v 1.1.1.1 2001/11/11 17:27:22 ben Exp
//

//
// 7/16/00 - Weave
//	Fixed error in send(SnmpPeer peer, SnmpTrapPdu trap) where
//	the trap was not actually encoded and stored in the buffer
//	that was transmitted. Bug found by Naz Irizarry.
//

package org.opennms.protocols.snmp;

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.SocketException;

import org.opennms.protocols.snmp.asn1.ASN1;
import org.opennms.protocols.snmp.asn1.AsnEncoder;
import org.opennms.protocols.snmp.asn1.AsnEncodingException;

/**
 * <P>
 * The trap session is used to send and receives SNMPv1 & v2 trap messages. The
 * messages are received on the configured port, or the default(162) port and
 * then decoded using the set ASN.1 codec. When messages are sent they are
 * encoded using the passed SnmpParameters object that is part of the SnmpPeer
 * object.
 * </P>
 * 
 * <P>
 * A trap message handler must be bound to the session in order to send or
 * receive messages.
 * </P>
 * 
 * @author <a href="http://www.opennms.org">OpenNMS </a>
 * @author <a href="mailto:[e-mail]">Brian Weaver </a>
 * @author Sowmya
 * @version 1.1.1.1 2001/11/11 17:27:22
 * 
 * @see SnmpTrapHandler
 */
public final class SnmpTrapSession extends Object {
    /**
     * <P>
     * Defines a error due to a thown exception. When the snmpTrapSessionError
     * method is invoked in the trap handler, the exception object is passed as
     * the ref parameter.
     * </P>
     * 
     * @see SnmpTrapHandler#snmpTrapSessionError
     * 
     */
    public final static int ERROR_EXCEPTION = -1;

    /**
     * <P>
     * Defines an error condition with an invalid PDU. For the moment this is
     * not actually used, but reserved for future use. When the session trap
     * handler error method is invoke the pdu in error should be passed as the
     * ref parameters
     * 
     * @see SnmpTrapHandler#snmpTrapSessionError
     */
    public final static int ERROR_INVALID_PDU = -2;

    /**
     * This is the default port where traps should be sent and received as
     * defined by the RFC.
     * 
     */
    public final static int DEFAULT_PORT = 162;

    /**
     * The default port were traps are sent and received by this session.
     */
    private int m_port;

    /**
     * The default SNMP trap callback handler. If this is not set and it is
     * needed then an SnmpHandlerNotDefinedException is thrown.
     * 
     */
    private SnmpPortal m_portal;

    /**
     * ASN.1 codec used to encode/decode snmp traps that are sent and received
     * by this session.
     */
    private AsnEncoder m_encoder;

    /**
     * The public trap handler that process received traps.
     * 
     */
    private SnmpTrapHandler m_handler;

    /**
     * If this boolean value is set then the receiver thread is terminated due
     * to an exception that was generated in either a handler or a socket error.
     * This is considered a fatal exception.
     */
    private boolean m_threadException;

    /**
     * This is the saved fatal exception that can be rethrown by the application
     */
    private Throwable m_why;

    /**
     * <P>
     * The internal trap handler class is designed to receive information from
     * the enclosed SnmpPortal class. The information is the processed and
     * forwarded when appropiate to the SnmpTrapHandler registered with the
     * session.
     * </P>
     * 
     */
    private class TrapHandler implements SnmpPacketHandler {
        /**
         * Who to pass as the session parameter
         */
        private SnmpTrapSession m_forWhom;

        /**
         * <P>
         * Creates a in internal trap handler to be the intermediary for the
         * interface between the SnmpPortal and the TrapSession.
         * </P>
         * 
         * @param sess
         *            The trap session reference.
         * 
         */
        public TrapHandler(SnmpTrapSession sess) {
            m_forWhom = sess;
        }

        /**
         * <P>
         * Processes the default V1 & V2 messages.
         * </P>
         * 
         * @param agent
         *            The sending agent
         * @param port
         *            The remote port.
         * @param version
         *            The SNMP Version of the message.
         * @param community
         *            The community string from the message.
         * @param pduType
         *            The type of pdu
         * @param pdu
         *            The actual pdu
         * 
         * @exception SnmpPduEncodingException
         *                Thrown if the pdu fails to decode.
         */
        public void processSnmpMessage(InetAddress agent, int port, SnmpInt32 version, SnmpOctetString community, int pduType, SnmpPduPacket pdu) throws SnmpPduEncodingException {
            if (version.getValue() != SnmpSMI.SNMPV2 && pduType != SnmpPduPacket.V2TRAP)
                return;

            try {
                m_handler.snmpReceivedTrap(m_forWhom, agent, port, community, pdu);
            } catch (Exception e) {
                // discard
            }
        }

        /**
         * <P>
         * Processes V1 trap messages.
         * </P>
         * 
         * @param agent
         *            The sending agent
         * @param port
         *            The remote port.
         * @param community
         *            The community string from the message.
         * @param pdu
         *            The actual pdu
         * 
         * @exception SnmpPduEncodingException
         *                Thrown if the pdu fails to decode.
         */
        public void processSnmpTrap(InetAddress agent, int port, SnmpOctetString community, SnmpPduTrap pdu) throws SnmpPduEncodingException {
            try {
                m_handler.snmpReceivedTrap(m_forWhom, agent, port, community, pdu);
            } catch (Exception e) {
                // discard
            }
        }

        /**
         * <P>
         * Invoked when bad datagrams are received.
         * </P>
         * 
         * @param p
         *            The datagram packet in question.
         * 
         */
        public void processBadDatagram(DatagramPacket p) {
            // do nothing - discard?
        }

        /**
         * <P>
         * Invoked when an exception occurs in the session.
         * </P>
         * 
         * @param e
         *            The exception.
         */
        public void processException(Exception e) {
            try {
                m_handler.snmpTrapSessionError(m_forWhom, ERROR_EXCEPTION, e);
            } catch (Exception e1) {
                // discard
            }
        }
    }

    /**
     * Used to disallow the default constructor.
     * 
     * @exception java.lang.UnsupportedOperationException
     *                Thrown if the constructor is called.
     * 
     */
    private SnmpTrapSession() throws java.lang.UnsupportedOperationException {
        throw new java.lang.UnsupportedOperationException("Illegal constructor call");
    }

    /**
     * The default SnmpTrapSession constructor.
     * 
     * @param handler
     *            The handler associated for message processing.
     * 
     * @exception java.net.SocketException
     *                If thrown it is from the creation of a DatagramSocket.
     * @exception java.lang.SecurityException
     *                Thrown if the security manager disallows the creation of
     *                the handler.
     */
    public SnmpTrapSession(SnmpTrapHandler handler) throws SocketException {
        m_port = DEFAULT_PORT;
        m_encoder = (new SnmpParameters()).getEncoder();
        m_threadException = false;
        m_why = null;
        m_handler = handler;
        m_portal = new SnmpPortal(new TrapHandler(this), m_encoder, m_port);
    }