[SNMP4J] SNMP4J Agent 1.3.2: NullPointer Exception when receiving GET requests with unknown community strings

[Frank Fock]

Hi Gianluca,

This is indeed a bug. Although it has no security
relevance, it has regarding authenticationFailure
trap generation and counter incrementation.

The below patch fixes it:

Index: SnmpCommunityMIB.java
===================================================================
--- SnmpCommunityMIB.java	(revision 1664)
+++ SnmpCommunityMIB.java	(working copy)
@@ -543,8 +543,10 @@
      if (coexistenceInfo == null) {
        return null;
      }
-    SortedSet cinfos = new 
TreeSet((SortedSet)coexistenceInfo.get(community));
+    SortedSet cinfos = (SortedSet)coexistenceInfo.get(community);
      if (cinfos != null) {
+      // make a copy to improve consistency on concurrent access
+      cinfos = new TreeSet(cinfos);
        Iterator it = cinfos.iterator();
        CoexistenceInfo[] infos = new CoexistenceInfo[cinfos.size()];
        for (int i=0; i<infos.length; i++) {

Best regards,
Frank

Gianluca Uberti wrote:
> Hi there,
> I am trying to develop an SNMP agent capable of responding to V1 and V2c
> requests with the help of SNMP 4J Agent framework version 1.3.2;
> my community string is configured as "public"; any time the agent
> receives a V2c GET request with a community string different from
> "public", it hangs and the following exception is logged:
> 
> 20091202 173258 CET [ERROR] <DefaultUDPTransportMapping> PTMA0000:
> java.lang.NullPointerException
> Trace for the exception:
> java.lang.NullPointerException
>     at java.util.TreeSet.<init>(TreeSet.java:154)
>     at
> org.snmp4j.agent.mo.snmp.SnmpCommunityMIB.getCoexistenceInfo(SnmpCommunityMIB.java:546)
>     at
> org.snmp4j.agent.CommandProcessor.processPdu(CommandProcessor.java:116)
>     at
> org.snmp4j.MessageDispatcherImpl.fireProcessPdu(MessageDispatcherImpl.java:610)
>     at
> org.snmp4j.MessageDispatcherImpl.dispatchMessage(MessageDispatcherImpl.java:287)
>     at
> org.snmp4j.MessageDispatcherImpl.processMessage(MessageDispatcherImpl.java:347)
>     at
> org.snmp4j.MessageDispatcherImpl.processMessage(MessageDispatcherImpl.java:309)
>     at
> org.snmp4j.transport.AbstractTransportMapping.fireProcessMessage(AbstractTransportMapping.java:83)
>     at
> org.snmp4j.transport.DefaultUdpTransportMapping$ListenThread.run(DefaultUdpTransportMapping.java:364)
>     at java.lang.Thread.run(Thread.java:619)
> 
> It does seem to me an actual SNMP 4J Agent framework issue...any help is
> appreciated.
> 
> Kind regards
> 
> GL
> 
> --
> Gianluca Uberti
> Kernel SW Engineer
> Mycom France s.a.r.l.
> t: +33 1 49 03 77 48
> f: +33 1 47 73 06 51
> e: gianluca.uberti at mycom-int.com
> w: www.mycom-int.com
> 
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