[SNMP4J] Strange NullPointerException...

[Frank Fock]

Hi,

The NullPointerException seems to be caused by a null
destAddress. Have you checked that it is set/created
correctly?

Best regards,
Frank

Menard, Matt wrote:
> First off let me say that I'm rather new to SNMP and this is the first
> time I've been involved in writing any SNMP code.  The problem I'm
> having is when I try to send a GETBULK request to the SNMP agent (SET
> and TRAPS do not have this problem; the requests are sent to the server
> just fine).  As soon as the "response = snmp.send(request, target);"
> line is executed, I receive the following exception.  
> 
>  
> 
> java.lang.NullPointerException
> 
>       at
> org.snmp4j.MessageDispatcherImpl.getTransport(MessageDispatcherImpl.java
> :204)
> 
>       at
> org.snmp4j.MessageDispatcherImpl.sendPdu(MessageDispatcherImpl.java:373)
> 
>       at org.snmp4j.Snmp.sendMessage(Snmp.java:955)
> 
>       at org.snmp4j.Snmp.send(Snmp.java:802)
> 
>       at org.snmp4j.Snmp.send(Snmp.java:758)
> 
>  
> 
> After trying, in vain, to figure this problem out, I thought that if I
> passed the Transport to the snmp.send() method directly, it would solve
> the problem.  That turned out to be incorrect and it just caused all the
> requests to time out.  Here are some of the particulars about this
> project:
> 
>  
> 
> SNMP version: 3
> 
> SNMP authentication: MD5
> 
> SNMP privacy: AES-128
> 
> IDE: JBuilder 2005
> 
> Java version: 1.4.1_09
> 
> SNMP4J version: 1.7.1
> 
>  
> 
> I've been banging my head against the wall trying to figure this out for
> a few days now.  Like I said, this only happens when I try to execute a
> GETBULK request.  I even went so far as to go through the
> SnmpRequest.java file that comes with the SNMP4J bundle and copy the
> code out there into my class (which you can see in the code included
> below) just incase there was something subtle I was missing.  
> 
>  
> 
> Any help would be greatly appreciated!
> 
>  
> 
> Thanks,
> Matt 
> 
>  
> 
> //------------- CODE --------------------------------
> 
> private PDU sendRequest(String ipAddress,
> 
>                         int port,
> 
>                         String username,
> 
>                         String authPassphrase,
> 
>                         String privPassphrase,
> 
>                         PDU request,
> 
>                         CommandResponder responder)
> 
> {
> 
>   PDU responsePDU = null;
> 
>  
> 
>   try
> 
>   {
> 
>     Snmp snmp = createSnmpSession(username, authPassphrase,
> privPassphrase);
> 
>  
> 
>  
> 
>  
> 
>     // Create the target and set the individual attributes of this SNMP
> 
>     // transaciton.
> 
>     Target target = createTarget(username,
> 
>                                  authPassphrase,
> 
>                                  privPassphrase,
> 
>                                  GenericAddress.parse("udp:" + ipAddress
> +  "/" + port));
> 
>  
> 
>     if(responder != null)
> 
>     {
> 
>       snmp.addCommandResponder(responder);
> 
>     }
> 
>  
> 
>     snmp.listen();
> 
>  
> 
>     ResponseEvent response = null;
> 
>  
> 
>     // This is the line that generates the exception.
> 
>     response = snmp.send(request, target);
> 
>     
> 
>     responsePDU = response.getResponse();
> 
>  
> 
>     snmp.close();
> 
>   }
> 
>  
> 
>   catch(IOException ioe)
> 
>   {
> 
>     ioe.printStackTrace();
> 
>   }
> 
>  
> 
>   catch(Exception e) 
> 
>   {
> 
>     e.printStackTrace();
> 
>   }
> 
>  
> 
>   return responsePDU;
> 
> }
> 
>  
> 
> //-------------------------------------------
> 
> // addUsmUser, lifted from the SnmpRequest.java class contained
> 
> // in the SNMP4J package.
> 
> private void addUsmUser(Snmp snmp,
> 
>                         String username,
> 
>                         String authPassphrase,
> 
>                         String privPassphrase)
> 
> {
> 
>   snmp.getUSM().addUser(new OctetString(username),
> 
>                         new UsmUser(new OctetString(username),
> 
>                                     AuthMD5.ID,
> 
>                                     new OctetString(authPassphrase),
> 
>                                     PrivAES128.ID,
> 
>                                     new OctetString(privPassphrase)));
> 
> }
> 
>  
> 
> //-------------------------------------------
> 
> // Portions of this code were derived from the SnmpRequest.java class...
> 
> private Snmp createSnmpSession(String username,
> 
>                                String authPassphrase,
> 
>                                String privPassphrase) throws IOException
> 
> {
> 
>   // Setup a transport over UDP
> 
>   AbstractTransportMapping transport =  new
> DefaultUdpTransportMapping();
> 
>  
> 
>   Snmp snmp =  new Snmp(transport);
> 
>  
> 
>   // Setup the user security model which will provide privacy
> (encryption)
> 
>   // and authentication.
> 
>   USM usm = new USM(SecurityProtocols.getInstance(),
> 
>                     new OctetString(MPv3.createLocalEngineID()), 0);
> 
>  
> 
>   SecurityModels.getInstance().addSecurityModel(usm);
> 
>   addUsmUser(snmp, username, authPassphrase, privPassphrase);
> 
>   return snmp;
> 
> }
> 
>  
> 
> //-------------------------------------------
> 
> // This class was also derived from the SnmpRequest.java
> 
> // class.
> 
> private Target createTarget(String username,
> 
>                             String authPassphrase,
> 
>                             String privPassphrase,
> 
>                             Address targetAddress)
> 
> {
> 
>   UserTarget target = new UserTarget();
> 
>  
> 
>   if(authPassphrase != null)
> 
>   {
> 
>     if(privPassphrase != null)
> 
>     {
> 
>       target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
> 
>     }
> 
>  
> 
>     else
> 
>     {
> 
>       target.setSecurityLevel(SecurityLevel.AUTH_NOPRIV);
> 
>     }
> 
>   }
> 
>  
> 
>   else
> 
>   {
> 
>     target.setSecurityLevel(SecurityLevel.NOAUTH_NOPRIV);
> 
>   }
> 
>  
> 
>   target.setAddress(targetAddress);
> 
>   target.setRetries(1);
> 
>   target.setTimeout(5000);
> 
>   target.setVersion(SnmpConstants.version3);
> 
>   target.setSecurityName(new OctetString(username));
> 
>  
> 
>   return target;
> 
> }
> 
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