[Pysnmp-dev] Potential oneliner bugs

[Mark M E. <mar...@ma...>]

I've run into a couple of issues that I think are bugs in the  
oneliner implementation.  I'm still learning my way around PySNMP, so  
apologies if my assumptions or conclusions are incorrect.

Issue #1:  Oneliner commands "leaking" sockets.

UdpTransportTarget.openClientMode() creates a transport via  
UdpSocketTransport().  A side effect of using the default parameters  
is that a new channel/socket is created and is registered in  
asyncore.socket_map.  The socket is never removed from  
asyncore.socket_map, it's never garbage collected and the socket is  
never closed.  The result is that instantiating and destroying large  
numbers of CommandGenerators will consume all of the systems socket  
resources.

I have a patch that works for me which is to pass a throw away  
dictionary as the sockMap.  Example:

pysnmp/entity/rfc3413/oneliner/cmdgen.py:

class UdpTransportTarget:
     ...
     def openClientMode(self):
         self.transport = udp.UdpSocketTransport(sock=None,
                                                 sockMap= 
{}).openClientMode()
         return self.transport

Issue #2:  CommandGenerator().nextCmd() does not work with V1 devices.

V1 devices terminate the list list of OIDs by returning an  
errorStatus of noSuchName(2), not by returning a value of endOfMib.   
CommandGenerator().nextCmd() considers a non-false errorStatus as an  
error (makes sense) and passes that failure to the caller.

I've hacked my local version to explicitly check for an errorStatus  
of 2, and clears that errorStatus/Index.  This seems to work, but  
there may be a cleaner solution.

pysnmp/entity/rfc3413/oneliner/cmdgen.py:

class CommandGenerator(AsynCommandGenerator):
     ...
     def nextCmd(self, authData, transportTarget, *varNames):
         def __cbFun(
             sendRequestHandle, errorIndication, errorStatus,  
errorIndex,
             varBindTable, (varBindHead, varBindTotalTable, appReturn)
             ):
             if errorStatus == 2:
                 # V1 terminates GETNEXT with an errorStatus of  
noSuchName
                 # rather than a value of endOfMib (which v2c.PDUAPI  
replaces
                 # with None).
                 errorStatus = errorStatus.clone(0)
                 errorIndex = errorIndex.clone(0)
                 pass
             if errorIndication or errorStatus:
             ...

Hopefully this information is helpful.

Regards,
Mark