SnmpRequest.java

/*******************************************************************************
 * This file is part of OpenNMS(R).
 *
 * Copyright (C) 2011 The OpenNMS Group, Inc.
 * OpenNMS(R) is Copyright (C) 1999-2011 The OpenNMS Group, Inc.
 *
 * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
 *
 * OpenNMS(R) 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.
 *
 * OpenNMS(R) 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 OpenNMS(R).  If not, see:
 *      http://www.gnu.org/licenses/
 *
 * For more information contact:
 *     OpenNMS(R) Licensing <license@opennms.org>
 *     http://www.opennms.org/
 *     http://www.opennms.com/
 *******************************************************************************/

package org.opennms.protocols.snmp;

import java.io.IOException;

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

/**
 * <P>
 * Implements a way to track outstanding SNMP pdu request. The object tracks the
 * pdu, it's sending parameters, the number of times send, and the last time
 * sent.
 * </P>
 * 
 * <P>
 * The SnmpRequest implements the Runnable interface and its run method is
 * invoked by the corresponding SnmpTimer when the request effectively expires.
 * The member m_expires refers the the expiretion of the request and pdu, not to
 * the failed response.
 * </P>
 * 
 * @author <A HREF="mailto:weave@oculan.com">Brian Weaver </A>
 * @author <A HERF="http://www.opennms.org">OpenNMS </A>
 * 
 * @version 1.1.1.1
 * 
 */
class SnmpRequest implements Runnable {
    /**
     * The session that created this request
     * 
     */
    SnmpSession m_session; // the seesion who sent it

    /**
     * The pdu transemited to the SnmpPeer.
     * 
     */
    SnmpSyntax m_pdu; // the PDU

    /**
     * The SnmpHandler to invoke for this request
     * 
     */
    SnmpHandler m_handler;

    /**
     * The number of times this request has been transmitted.
     * 
     */
    int m_timesSent; // number of times sent

    /**
     * When set the request as a whole has expired and should no longer be
     * process by any methods. It is effectively waiting for garbage collection.
     * 
     */
    boolean m_expired; // when set DO NOT PROCESS

    /**
     * Used to create an SnmpRequest object. This constructor sets the fields to
     * their default value along with the passed parameters.
     * 
     * @param session
     *            The sending session
     * @param pdu
     *            The pdu to send to the remote
     * @param handler
     *            The handler to invoke!
     * 
     */
    SnmpRequest(SnmpSession session, SnmpPduPacket pdu, SnmpHandler handler) {
        super();
        m_session = session;
        m_pdu = pdu;
        m_expired = false;
        m_timesSent = 0;
        m_handler = handler;
    }

    /**
     * Used to create an SnmpRequest object. This constructor sets the fields to
     * their default value along with the passed parameters.
     * 
     * @param session
     *            The sending session
     * @param pdu
     *            The pdu to send to the remote
     * @param handler
     *            The handler to invoke!
     * 
     */
    SnmpRequest(SnmpSession session, SnmpPduTrap pdu, SnmpHandler handler) {
        super();
        m_session = session;
        m_pdu = pdu;
        m_expired = false;
        m_timesSent = 0;
        m_handler = handler;
    }

    /**
     * Used to process the timeout of an SnmpRequest. The method is invoked by
     * the session timer object. If the request has "expired" then no processing
     * occurs. If the number of retries have exceeded the session parameters
     * then the SnmpHandler's snmpTimeoutError() method is invoked. If an error
     * occurs transmiting the pdu then the snmpInternalError() method is
     * invoked.
     * 
     * @see SnmpHandler
     * @see SnmpPduRequest
     * @see SnmpSession
     */
    public void run() {
        if (m_expired)
            return;

        if (m_timesSent <= m_session.getPeer().getRetries()) {
            m_timesSent++;
            try {
                //
                // An SNMP Trap command should only be sent ONCE!
                //
                m_session.transmit(this);
                if (m_pdu instanceof SnmpPduPacket) {
                    if (((SnmpPduPacket) m_pdu).getCommand() != SnmpPduPacket.V2TRAP)
                        m_session.getTimer().schedule(this, m_session.getPeer().getTimeout());
                    else
                        m_expired = true;
                } else if (m_pdu instanceof SnmpPduTrap) {
                    m_expired = true;
                }
            } catch (IOException err) {
                m_expired = true;
                try {
                    m_handler.snmpInternalError(m_session, SnmpSession.ERROR_IOEXCEPTION, m_pdu);
                } catch (Exception e) {
                    // ignore
                }
            } catch (SnmpPduEncodingException err) {
                m_expired = true;
                try {
                    m_handler.snmpInternalError(m_session, SnmpSession.ERROR_ENCODING, m_pdu);
                } catch (Exception e) {
                    // ignore
                }
            } catch (AsnEncodingException err) {
                m_expired = true;
                try {
                    m_handler.snmpInternalError(m_session, SnmpSession.ERROR_ENCODING, m_pdu);
                } catch (Exception e) {
                    // ignore
                }
            }
        } else {
            m_expired = true;
            try {
                m_handler.snmpTimeoutError(m_session, m_pdu);
            } catch (Exception e) {
                // ignore
            }
        }
    }
}