messagedispatcherimpl.java

一个已经完善的极其方便的实现snmp的开发包

/*_############################################################################
  _##
  _##  SNMP4J - MessageDispatcherImpl.java
  _##
  _##  Copyright (C) 2003-2008  Frank Fock and Jochen Katz (SNMP4J.org)
  _##
  _##  Licensed under the Apache License, Version 2.0 (the "License");
  _##  you may not use this file except in compliance with the License.
  _##  You may obtain a copy of the License at
  _##
  _##      http://www.apache.org/licenses/LICENSE-2.0
  _##
  _##  Unless required by applicable law or agreed to in writing, software
  _##  distributed under the License is distributed on an "AS IS" BASIS,
  _##  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  _##  See the License for the specific language governing permissions and
  _##  limitations under the License.
  _##
  _##########################################################################*/

package org.snmp4j;

import java.io.IOException;
import java.util.*;

import org.snmp4j.asn1.*;
import org.snmp4j.event.*;
import org.snmp4j.log.*;
import org.snmp4j.mp.*;
import org.snmp4j.smi.*;
import java.nio.ByteBuffer;
import org.snmp4j.transport.UnsupportedAddressClassException;

/**
 * The <code>MessageDispatcherImpl</code> decodes and dispatches incoming
 * messages using {@link MessageProcessingModel} instances and encodes
 * and sends outgoing messages using an appropriate {@link TransportMapping}
 * instances.
 * <p>
 * The method {@link #processMessage} will be called from a
 * <code>TransportMapping</code> whereas the method {@link #sendPdu} will be
 * called by the application.
 *
 * @see Snmp
 * @see TransportMapping
 * @see MessageProcessingModel
 * @see MPv1
 * @see MPv2c
 * @see MPv3
 *
 * @author Frank Fock
 * @version 1.8
 */
public class MessageDispatcherImpl implements MessageDispatcher {

  private static final LogAdapter logger =
      LogFactory.getLogger(MessageDispatcherImpl.class);

  private Vector mpm = new Vector(3);
  private Map transportMappings = new Hashtable(5);

  private int nextTransactionID = new Random().nextInt(Integer.MAX_VALUE-2)+1;
  transient private Vector commandResponderListeners;
  private transient Vector counterListeners;
  private transient Vector authenticationFailureListeners;

  private boolean checkOutgoingMsg = true;

  /**
   * Default constructor creates a message dispatcher without any associated
   * message processing models.
   */
  public MessageDispatcherImpl() {
  }

  /**
   * Adds a message processing model to this message dispatcher. If a message
   * processing model with the same ID as the supplied one already exists it
   * will not be changed. Please call {@link #removeMessageProcessingModel}
   * before to replace a message processing model.
   * @param model
   *    a MessageProcessingModel instance.
   */
  public synchronized void addMessageProcessingModel(MessageProcessingModel model) {
    while (mpm.size() <= model.getID()) {
      mpm.add(null);
    }
    if (mpm.get(model.getID()) == null) {
      mpm.set(model.getID(), model);
    }
  }

  /**
   * Removes a message processing model from this message dispatcher.
   * @param model
   *    a previously added MessageProcessingModel instance.
   */
  public synchronized void removeMessageProcessingModel(MessageProcessingModel model) {
    mpm.set(model.getID(), null);
  }

  /**
   * Adds a transport mapping. When an outgoing message is processed where
   * no specific transport mapping has been specified, then the
   * message dispatcher will use the transport mapping
   * that supports the supplied address class of the target.
   * @param transport
   *    a TransportMapping instance. If there is already another transport
   *    mapping registered that supports the same address class, then
   *    <code>transport</code> will be registered but not used for messages
   *    without specific transport mapping.
   */
  public synchronized void addTransportMapping(TransportMapping transport) {
    List transports =
        (List) transportMappings.get(transport.getSupportedAddressClass());
    if (transports == null) {
      transports = new LinkedList();
      transportMappings.put(transport.getSupportedAddressClass(), transports);
    }
    transports.add(transport);
  }

  /**
   * Removes a transport mapping.
   * @param transport
   *    a previously added TransportMapping instance.
   * @return
   *    the supplied TransportMapping if it has been successfully removed,
   *    <code>null</code>otherwise.
   */
  public TransportMapping removeTransportMapping(TransportMapping transport) {
    List tm =
        (List) transportMappings.remove(transport.getSupportedAddressClass());
    if (tm != null) {
      if (tm.remove(transport)) {
        return transport;
      }
    }
    return null;
  }

  /**
   * Gets a collection of all registered transport mappings.
   * @return
   *    a Collection instance.
   */
  public Collection getTransportMappings() {
    ArrayList l = new ArrayList(transportMappings.size());
    synchronized (transportMappings) {
      for (Iterator it = transportMappings.values().iterator(); it.hasNext();) {
        List tm = (List) it.next();
        l.addAll(tm);
      }
    }
    return l;
  }

  public synchronized int getNextRequestID() {
    int nextID = nextTransactionID++;
    if (nextID <= 0) {
      nextID = 1;
      nextTransactionID = 2;
    }
    return nextID;
  }

  protected PduHandle createPduHandle() {
    return new PduHandle(getNextRequestID());
  }

  /**
   * Sends a message using the <code>TransportMapping</code> that has been
   * assigned for the supplied address type.
   *
   * @param transport
   *    the transport mapping to be used to send the message.
   * @param destAddress
   *    the transport address where to send the message. The
   *    <code>destAddress</code> must be compatible with the supplied
   *    <code>transport</code>.
   * @param message
   *    the SNMP message to send.
   * @throws IOException
   *    if an I/O error occured while sending the message or if there is
   *    no transport mapping defined for the supplied address type.
   */
  protected void sendMessage(TransportMapping transport,
                             Address destAddress, byte[] message)
      throws IOException
  {
    if (destAddress instanceof GenericAddress) {
      destAddress = ((GenericAddress)destAddress).getAddress();
    }
    if (transport != null) {
      transport.sendMessage(destAddress, message);
    }
    else {
      String txt = "No transport mapping for address class: "+
                   destAddress.getClass().getName()+"="+destAddress;
      logger.error(txt);
      throw new IOException(txt);
    }
  }

  /**
   * Returns a transport mapping that can handle the supplied address.
   * @param destAddress
   *    an Address instance.
   * @return
   *    a <code>TransportMapping</code> instance that can be used to sent
   *    a SNMP message to <code>destAddress</code> or <code>null</code> if
   *    such a transport mapping does not exists.
   * @since 1.6
   */
  public TransportMapping getTransport(Address destAddress) {
    Class addressClass = destAddress.getClass();
    List l = (List) transportMappings.get(addressClass);
    if ((l != null) && (l.size() > 0)) {
      TransportMapping transport = (TransportMapping)l.get(0);
      return transport;
    }
    return null;
  }

  /**
   * Actually decodes and dispatches an incoming SNMP message using the supplied
   * message processing model.
   *
   * @param sourceTransport
   *   a <code>TransportMapping</code> that matches the incomingAddress type.
   * @param mp
   *   a <code>MessageProcessingModel</code> to process the message.
   * @param incomingAddress
   *   the <code>Address</code> from the entity that sent this message.
   * @param wholeMessage
   *   the <code>BERInputStream</code> containing the SNMP message.
   * @throws IOException
   *   if the message cannot be decoded.
   */
  protected void dispatchMessage(TransportMapping sourceTransport,
                                 MessageProcessingModel mp,
                                 Address incomingAddress,
                                 BERInputStream wholeMessage) throws IOException {
    MutablePDU pdu = new MutablePDU();
    Integer32 messageProcessingModel = new Integer32();
    Integer32 securityModel = new Integer32();
    OctetString securityName = new OctetString();
    Integer32 securityLevel = new Integer32();

    PduHandle handle = createPduHandle();

    Integer32 maxSizeRespPDU =
        new Integer32(sourceTransport.getMaxInboundMessageSize());
    StatusInformation statusInfo = new StatusInformation();
    MutableStateReference mutableStateReference = new MutableStateReference();
    // add the transport mapping to the state reference to allow the MP to
    // return REPORTs on the same interface/port the message had been received.
    StateReference stateReference = new StateReference();
    stateReference.setTransportMapping(sourceTransport);
    stateReference.setAddress(incomingAddress);
    mutableStateReference.setStateReference(stateReference);

    int status = mp.prepareDataElements(this, incomingAddress, wholeMessage,
                                        messageProcessingModel, securityModel,
                                        securityName, securityLevel, pdu,
                                        handle, maxSizeRespPDU, statusInfo,
                                        mutableStateReference);
    if (mutableStateReference.getStateReference() != null) {
      // make sure transport mapping is set
      mutableStateReference.
          getStateReference().setTransportMapping(sourceTransport);
    }
    if (status == SnmpConstants.SNMP_ERROR_SUCCESS) {
      // dispatch it
      CommandResponderEvent e =
          new CommandResponderEvent(this,
                                    sourceTransport,
                                    incomingAddress,
                                    messageProcessingModel.getValue(),
                                    securityModel.getValue(),
                                    securityName.getValue(),
                                    securityLevel.getValue(),
                                    handle,
                                    pdu.getPdu(),
                                    maxSizeRespPDU.getValue(),
                                    mutableStateReference.getStateReference());
      fireProcessPdu(e);
    }
    else {
      switch (status) {
        case SnmpConstants.SNMP_MP_UNSUPPORTED_SECURITY_MODEL:
        case SnmpConstants.SNMP_MP_WRONG_USER_NAME:
        case SnmpConstants.SNMP_MP_USM_ERROR: {
          AuthenticationFailureEvent event =
              new AuthenticationFailureEvent(this, incomingAddress,
                                             sourceTransport, status,
                                             wholeMessage);
          fireAuthenticationFailure(event);
          break;
        }
      }
      logger.warn(statusInfo.toString());
    }
  }

  public void processMessage(TransportMapping sourceTransport,
                             Address incomingAddress,
                             ByteBuffer wholeMessage) {
    processMessage(sourceTransport, incomingAddress,
                   new BERInputStream(wholeMessage));
  }

  public void processMessage(TransportMapping sourceTransport,
                             Address incomingAddress,
                             BERInputStream wholeMessage) {
    fireIncrementCounter(new CounterEvent(this, SnmpConstants.snmpInPkts));
    if (!wholeMessage.markSupported()) {
      String txt = "Message stream must support marks";
      logger.error(txt);
      throw new IllegalArgumentException(txt);
    }
    try {
      wholeMessage.mark(16);
      BER.MutableByte type = new BER.MutableByte();
      // decode header but do not check length here, because we do only decode
      // the first 16 bytes.
      BER.decodeHeader(wholeMessage, type, false);
      if (type.getValue() != BER.SEQUENCE) {
        logger.error("ASN.1 parse error (message is not a sequence)");
        CounterEvent event = new CounterEvent(this,
                                              SnmpConstants.snmpInASNParseErrs);
        fireIncrementCounter(event);
      }
      Integer32 version = new Integer32();
      version.decodeBER(wholeMessage);
      MessageProcessingModel mp = getMessageProcessingModel(version.getValue());
      if (mp == null) {
        logger.warn("SNMP version "+version+" is not supported");
        CounterEvent event = new CounterEvent(this,
                                              SnmpConstants.snmpInBadVersions);
        fireIncrementCounter(event);
      }
      else {
        // reset it
        wholeMessage.reset();
        // dispatch it
        dispatchMessage(sourceTransport, mp, incomingAddress, wholeMessage);
      }
    }
    catch (Exception ex) {
      logger.error(ex);
      if (logger.isDebugEnabled()) {
        ex.printStackTrace();
      }
      if (SNMP4JSettings.isFowardRuntimeExceptions()) {
        throw new RuntimeException(ex);
      }
    }
    catch (OutOfMemoryError oex) {
      logger.error(oex);
      if (SNMP4JSettings.isFowardRuntimeExceptions()) {
        throw oex;
      }
    }
  }

  public PduHandle sendPdu(Address transportAddress,
                           int messageProcessingModel,
                           int securityModel,
                           byte[] securityName,
                           int securityLevel,
                           PDU pdu,
                           boolean expectResponse) throws MessageException {
    return sendPdu(null, transportAddress, messageProcessingModel,
                   securityModel, securityName, securityLevel,
                   pdu, expectResponse);
  }

  public PduHandle sendPdu(TransportMapping transport,
                           Address transportAddress,
                           int messageProcessingModel,
                           int securityModel,
                           byte[] securityName,
                           int securityLevel,
                           PDU pdu,
                           boolean expectResponse,
                           PduHandleCallback pduHandleCallback)