Re: [lwip-devel] [Question/Issue] SNMP 'set_value' always return SNMP_ERR_COMMITFAILED or SNMP_ERR_UNDOFAILED on error

[Dirk Ziegelmeier]

I guess you have a problem in your implementation - when SNMP set is performed, each node gets a "set_test" AND a "set_value" call. Your "set_test" call says everything is fine, but your "set_value" call returns WrongValue - according to RFC1448 a failure in the "apply" phase of the SNMP set request is mapped to CommitFailed or UndoFailed in the response. A failure in the "test" phase would return the error value you that expect. -> Check your set_test implementation of the affected node.

Ciao
Dirk

--
Dirk Ziegelmeier * address@hidden * http://www.ziegelmeier.net

On Mon, Oct 23, 2017 at 6:03 PM, Maxime Guyon <address@hidden> wrote:

Hello,

I have a question/remark with snmp module when a SET request fail:

In file "snmp_msg.c" at line 717, there is this code:

if (node_instance.set_value(&node_instance, vb.value_len, vb.value) != SNMP_ERR_NOERROR) {

            if (request->inbound_varbind_enumerator.varbind_count == 1) {

              request->error_status = SNMP_ERR_COMMITFAILED;

            } else {

              /* we cannot undo the set operations done so far */

              request->error_status = SNMP_ERR_UNDOFAILED;

            }

          }

On error, this force the return value of an SNMP SET request to be SNMP_ERR_COMMITFAILED or SNMP_ERR_UNDOFAILED .

So if I returned another error like SNMP_ERR_WRONGVALUE, then I will never know that it was this error which failed the request because my return value is replaced.

My FIX for the moment is to simply remove the following line:

  if (request->inbound_varbind_enumerator.varbind_count == 1) {

              request->error_status = SNMP_ERR_COMMITFAILED;

            } else {

              /* we cannot undo the set operations done so far */

              request->error_status = SNMP_ERR_UNDOFAILED;

            }

          }

Is there any mistake here?
Is there a reason that the return code of a SET request is overwriten? 

Regards.

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