[Unbound-users] Potential Bug
wouter at NLnetLabs.nl
Thu Jun 30 11:04:21 UTC 2011
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On 06/29/2011 04:59 PM, W.C.A. Wijngaards wrote:
> Hi Robert,
> On 06/29/2011 04:32 PM, Robert Fleischman wrote:
>> I said:
>>>> Potential Bug: In "mesh_state_cleanup", I noticed that
>>>> "comm_point_drop_reply" is called to remove unset replies, HOWEVER, it
>>>> does not appear that either "stats_dropped" is incremented or more
>>>> importantly "num_reply_addrs" is not decremented. Doesn't this lack
>>>> of a decrement potentially cause the "16 times" limit go into effect and
>>>> prematurely drop queries?
>> Your response:
>>> The num_reply_addrs is decremented when a reply is sent (which can be an
>>> error if the mesh state is removed because of an error). The
>>> mesh_state_cleanup indeed does not cleanup the num_reply_addrs value
>>> correctly, but this routine is only called from the mesh_state_delete
>>> function. Thus it does not present a bug.
>> Okay, I agree.
>> Consider this: Assume my Internet connection goes out for a bit, thus
>> no replies come
>> in, so, queries pile up quickly.
>> Consider the following code path during this outage:
>> mesh_new_client() -> mesh_make_new_space() -> Code in
>> mesh_make_new_space() decides jostle is needed ->
>> mesh_state_delete() -> mesh_state_cleanup()
>> That causes num_reply_addrs to NOT be decremented.
>> Now my Internet connection comes back, BUT, num_reply_addrs got so
>> high that the "16 times" limit goes into effect. Now I get all my
>> queries dropped even though there is no error or problem anymore.
>> My temporary outage caused num_reply_addrs to grow and there is no way
>> for it to come back down. So, I'm stuck dropping queries until a
>> restart of the server.
> You are correct, and I was wrong. It should be fixed.
> Thanks for the report (and persistence :-) )
Fixed in the svn trunk development of unbound.
This code path is triggered by jostled queries. It is not triggered by
ordinary timeouts or servfails.
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