[Net-snmp-patches] [ net-snmp-Patches-3423915 ] default retry in 4.7.1 is 0, not 5

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Patches item #3423915, was opened at 2011-10-14 13:25
Message generated for change (Comment added) made by fenner
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Category: None
Group: None
Status: Closed
Resolution: None
Priority: 5
Private: No
Submitted By: Bill Fenner (fenner)
Assigned to: Robert Story (rstory)
Summary: default retry in 4.7.1 is 0, not 5

Initial Comment:
In 4.6.1, as documented, snmpget (and all snmp commands) retry 5 times (for a total of 6):

~/482f @bs1.pa% strace -o /tmp/4.6.1-snmpget-retries.txt snmpget 10.0.0.0 sysDescr.0
Timeout: No Response from 10.0.0.0.
~/482f @bs1.pa% grep select /tmp/4.6.1-snmpget-retries.txt 
select(6, [5], NULL, NULL, {0, 999961}) = 0 (Timeout)
select(6, [5], NULL, NULL, {0, 999955}) = 0 (Timeout)
select(6, [5], NULL, NULL, {0, 999952}) = 0 (Timeout)
select(6, [5], NULL, NULL, {0, 999950}) = 0 (Timeout)
select(6, [5], NULL, NULL, {0, 999910}) = 0 (Timeout)
select(6, [5], NULL, NULL, {0, 999957}) = 0 (Timeout)

In 4.7.1, there are zero retries:


~/nar @bs14.sjc% strace -o /tmp/4.7.1-snmpget-retries.txt snmpget 10.0.0.0 sysDescr.0
Timeout: No Response from 10.0.0.0.
~/nar @bs14.sjc% grep select /tmp/4.7.1-snmpget-retries.txt 
select(6, [5], NULL, NULL, {0, 999959}) = 0 (Timeout)

(I ran "snmpget -Dread_config" and made sure that there was no entry found for retries in any config file)

It looks like the code to set retries assumes that netsnmp_ds_get_int returns a negative number when there is no value.

        int retry = netsnmp_ds_get_int(NETSNMP_DS_LIBRARY_ID,
                                       NETSNMP_DS_LIB_RETRIES);
        if (retry < 0)
            session->retries = DEFAULT_RETRIES;
        else
            session->retries = retry;

but, it returns 0, so we never use DEFAULT_RETRIES.




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Comment By: Bill Fenner (fenner)
Date: 2011-10-18 07:08

Message:
You're right, I was trying to simplify since that code wasn't used in the
normal case, but there's no particular harm in using the default when
someone specifies "retries -1".


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Comment By:  (bvassche)
Date: 2011-10-18 06:02

Message:
Why to remove the "retry < 0" code ? I think it makes sense to set
"retries" to zero if the user has specified a negative value.

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Comment By: Bill Fenner (fenner)
Date: 2011-10-15 21:16

Message:
I tried with my suggested change to your patch (I uploaded precisely the
patch that I tried), and I got the desired behavior: 5 retries, for a total
of 6 calls to select.


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Comment By: Bill Fenner (fenner)
Date: 2011-10-15 08:07

Message:
Hi Bart,

Thanks for the patch.  I don't quite have time to test it right now, but
it looks sensible.  If I was going down that path, I would simplify the
code to just unconditionally use netsnmp_ds_get_int( ...,
NETSNMP_DS_LIB_RETRIES) since you know that it's set to DEFAULT_RETRIES.

I hope to get to try your patch this weekend.
 

----------------------------------------------------------------------

Comment By:  (bvassche)
Date: 2011-10-15 05:58

Message:
Thanks for the detailed bug report. Does the attached patch help ?

----------------------------------------------------------------------

Comment By: Bill Fenner (fenner)
Date: 2011-10-14 13:30

Message:
This code was added in git commit 6cac050a476ac5bcf36ac497c518b7f465b0d5b9
.

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