Re: [lwip-devel] SNMPv2 SetRequest fail response

[Marco Veeneman]

I'm sorry for the duplicate mail in both lwip-users and lwip-devel lists..

I had sent this mail to the lwip-users list over 4 hours ago but it didn't show up there. Now after sending this mail it also arrived at lwip-users..

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Van: lwip-devel <lwip-devel-bounces+address@hidden> namens Marco Veeneman <address@hidden>
Verzonden: donderdag 8 september 2016 20:37
Aan: address@hidden
Onderwerp: [lwip-devel] SNMPv2 SetRequest fail response

 

Hi,

I'm facing a problem with SNMP again and I would like to hear your thoughts about it.

In <sometable>_get_instance, if no valid instance oid for a row is found, it returns SNMP_ERR_NOSUCHINSTANCE.

If a user requests to set an invalid table oid using SNMPv1, the SNMP agent responds with 'error-status: noSuchName (2)'.

This is OK.

If a user requests to set an invalid table oid using SNMPv2, the SNMP agent doesn't respond at all. It just drops the packet. 

This happens because of the following code in snmp_complete_outbound_frame() (at line 1366 in snmp_msg.c):

    if (request->error_status >= SNMP_VARBIND_EXCEPTION_OFFSET) {

        return ERR_ARG;

    }

which stops further processing of the request.

It would be better if the SNMP agent would respond with a message with error-status set to some value. What would be the best solution here?

Marco