[SNMP4J] SNMP broadcasts, PDUv1 with Counter64 (in 1.9.1)

[Christof Meerwald]

Hi,

it appears that with 1.9.1 SNMP broadcasts don't work any more - to be
more precise, you now only get the first response (with code that
worked perfectly fine with previous snmp4j versions). I think this is
related to the following "fix" in 1.9.1:

"Fixed: With async request processing and retry>0 there could have been
a race condition where a response event had been generated twice for a
request."

which appears to now only allow a single response event for each
request (even if the request is not cancelled in the listener as
mentioned in the JavaDoc: "Not canceling a request immediately can be
useful when sending a request to a broadcast address.")


I also noticed that 1.9.1 now contains a factory interface for creating
the PDU class for incoming messages. While this allows one to provide a
PDUv1 class that doesn't throw an exception when encountering a
Counter64 value, it's still a bit of a hassle as it requires quite a
bit of code duplication. I think, snmp4j could quite easily simplify
that particular case further by moving the Counter64 check into a
separate method. That way, a derived "PDUv1WithCounter64" could easily
overwrite that method without having to duplicate any of the decodeBER
code. So my proposal would be to add a new protected method to PDUv1:

protected void checkVariableBindingSyntax(VariableBinding vb)
  throws IOException
{
  if (vb.getSyntax() == SMIConstants.SYNTAX_COUNTER64) {
    throw new MessageException("Counter64 encountered in SNMPv1 PDU
"+
                               "(RFC 2576 §4.1.2.1)");
  }
}

and call checkVariableBindingSyntax(vb) in decodeBER (line 169).

Any thoughts on this?


Christof

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