[SNMP4J] Problems with Request ID

[Frank Fock]

Phil,

I totally agree. Mixing signed and unsigned is the real problem!
So I sure will leave it as an Integer32. BTW, the bug was caused
by weakness that let me implement a workaround for some
ill SNMP agents that cannot handle negative request IDs. When
I added the (now) malicious code, SNMP4J was used for
manager applications in the first place. The fault was to not handle
response PDUs differently.

Best regards,
Frank

PHIL BERGSTRESSER wrote:

>Frank,
>
>Whoa. Think about that request. The requestID is defined as a signed
>INTEGER32 in SNMP. Shouldn't this be adequate for Java?
>
>Phil
>
>-----Original Message-----
>From: snmp4j-bounces at agentpp.org [mailto:snmp4j-bounces at agentpp.org] On
>Behalf Of Angel Angelov
>Sent: Friday, November 11, 2005 1:44 PM
>To: SNMP4J at agentpp.org
>Subject: Re: [SNMP4J] Problems with Request ID
>
>Hi Frank,
>thanks for the source code patch.
>I applied it and tested it. It fixes the problem by response PDUs with
>request ID > 2^31.
>
>Will you put this source code modification in to the next SNMP4J
>release?
>
>What do you think to change the type of requestID from Integer32 to
>UnsignedInteger32?
>In this way you can avoid other similar problems...
>
>And one suggestion:
>It will be useful to put the release version in:
> - package name like SNMP4J-1.6a.jar
> - in jar manifest file like "SNMP4J-Version: 1.6a
> - log line with the version
>One or more of this items will help the developers to control better the
>library release they use.
>
>Thanks for the great library and for the great support.
>
>Regards,
>Angel
>
>
>
>Frank Fock wrote:
>
>  
>
>>Hi Angel,
>>
>>Please try to replace row 383-391 of MessageDispatcherImpl by
>>
>>     // if request ID is == 0 then create one here, otherwise use the 
>>request
>>     // ID because it may be a resent request.
>>     PduHandle pduHandle;
>>     if ((pdu.getRequestID().getValue() == 0) &&
>>         (pdu.getType() != PDU.RESPONSE)) {
>>       pduHandle = createPduHandle();
>>     }
>>     else {
>>       pduHandle = new PduHandle(pdu.getRequestID().getValue());
>>     }
>>
>>This will fix the problem, I suppose.
>>
>>Best regards,
>>Frank
>>
>>Angel Angelov wrote:
>>
>>    
>>
>>>Hi Frank,
>>>I upgraded snmp4j to v1.6a, but I still get problems with request IDs
>>>      
>>>
>>>>2^31.
>>>>        
>>>>
>>>Here is a packet I receive:
>>>2005-11-10 13:25:01,215 [DefaultUDPTransportMapping_0.0.0.0/1162]
>>>DEBUG org.snmp4j.transport.DefaultUdpTransportMapping - Received 
>>>message from /172.25.2.20/40975 with length 63:
>>>30:3d:02:01:00:04:06:70:75:62:6c:69:63:a0:30:02:04:8d:ef:89:54:02:01:
>>>00:02:01:00:30:22:30:0f:06:0b:2b:06:01:04:01:86:8d:1f:64:01:01:05:00:
>>>30:0f:06:0b:2b:06:01:04:01:86:8d:1f:64:01:02:05:00
>>>
>>>
>>>The request ID is set to -1913681580 in to the PDU object When I 
>>>snoop the UDP packets on my network interface I see that the request 
>>>ID have value 0x8DEF8954
>>>
>>>I crate response PDU using the same request ID -1913681580.
>>>This is the response packet:
>>>2005-11-10 13:25:01,218 [DefaultUDPTransportMapping_0.0.0.0/1162]
>>>DEBUG org.snmp4j.transport.DefaultUdpTransportMapping - Sending 
>>>message to 172.25.2.20/40975 with length 71:
>>>30:45:02:01:00:04:06:70:75:62:6c:69:63:a2:38:02:04:4f:76:6d:0a:02:01:
>>>00:02:01:00:30:2a:30:13:06:0b:2b:06:01:04:01:86:8d:1f:64:01:01:42:04:
>>>03:2b:00:00:30:13:06:0b:2b:06:01:04:01:86:8d:1f:64:01:02:42:04:02:a0:
>>>54:20
>>>
>>>When I snoop the UDP packets again I see that the request ID of the 
>>>response PDU have value 0x4F766D0A
>>>
>>>Because the IDs are different, the response is not ignored from the 
>>>agent.
>>>
>>>The GET request is generated from Cricket
>>>(http://cricket.sourceforge.net)
>>>
>>>Frank, can you reproduce the problem with the packet data I send to
>>>      
>>>
>you?
>  
>
>>>Regards,
>>>Angel
>>>
>>>
>>>            _______________________________________________
>>>SNMP4J mailing list
>>>SNMP4J at agentpp.org
>>>http://lists.agentpp.org/mailman/listinfo/snmp4j
>>>
>>>
>>> 
>>>
>>>      
>>>
>>    
>>
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>  
>


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