Prefetch Serve expired behavior per cache

[ashok athukuri]

Hello Everyone,

Can anyone  guide me here ?

Thanks,
Ashok

On Fri, May 13, 2022 at 3:51 PM ashok athukuri <athukuriashok at gmail.com>
wrote:

> Hello George,
>
>
> Thanks for the quick response, Yes I am using libunbound version 1.12
>
> Yes I am setting config for a separate context
>
> but SERVE_EXPIRED_REPLY_TTL  is a global variable and the same is used in different places example dns.c tomsg() function
> I feel because of this global variable this part of the code is creating problems for different cache conf.
> I tested with multiple caches and its holding only 1 configuration (I doubt it because of code services/cache/dns.c#594)
>
>
> SERVE_EXPIRED_REPLY is assigned in build/util/config_file.c#2056 (config_apply)2056  	
>
> SERVE_EXPIRED_REPLY_TTL = (time_t)config->serve_expired_reply_ttl;
>
>
> below code tomsg() is depending on SERVE_EXPIRED_REPLY_TTL to make this works these variables should be set in the context before actually calling tomsg() function.
>
> Else these values may remain un changed and apply for all caches.
>
> As you can see in the below code services/cache/dns.c#594
> 589  	msg = gen_dns_msg(region, q, r->rrset_count);
>
> 590  	if(!msg) return NULL;
>
> 591  	msg->rep->flags = r->flags;
>
> 592  	msg->rep->qdcount = r->qdcount;
>
> 593  	msg->rep->ttl = is_expired
>
> 594  		?SERVE_EXPIRED_REPLY_TTL
>
> 595  		:r->ttl - now;
>
> 596  	if(r->prefetch_ttl > now)
>
> 597  		msg->rep->prefetch_ttl = r->prefetch_ttl - now;
>
> 598  	else
>
> 599  		msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
>
> 600  	msg->rep->serve_expired_ttl = msg->rep->ttl + SERVE_EXPIRED_TTL;
>
>
> Thanks,
>
> Ashok
>
>
>
> On Fri, May 13, 2022 at 3:07 PM George Thessalonikefs via Unbound-users <
> unbound-users at lists.nlnetlabs.nl> wrote:
>
>> Hi Ashok,
>>
>> The Unbound daemon runs as one cache resolver.
>> Are you perhaps using libunound and creating your own contexts?
>> In that case yes the options are per context.
>> You can have different options per context though, if you use the
>> 'ub_ctx_set_option' function.
>> Since the options you mention are configurable and not hard coded, the
>> aforementioned function works on them.
>>
>> Best regards,
>> -- George
>>
>> On 13/05/2022 07:25, ashok athukuri via Unbound-users wrote:
>> > Hello All,
>> >
>> > I am a newbie for unbound, please apologize if my question is wrong or
>> > my understanding is wrong.
>> >
>> > I see below variables make unbound to use a single configuration for
>> all
>> > cache resolvers.
>> > As these variables are global and don't bind with any unbound context
>> or
>> > configuration for each cache
>> >
>> > I wonder how to solve this problem? as I need different cache conf for
>> > different cache resolvers.
>> >
>> > 64   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#64>/**
>> If we serve expired entries and prefetch them */
>> > 65   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#65>THREAD
>> <https://indexing2.f5net.com/source/s?defs=THREAD&project=tmos-dns-bugs>
>> *int*  SERVE_EXPIRED  <
>> https://indexing2.f5net.com/source/s?refs=SERVE_EXPIRED&project=tmos-dns-bugs>
>> = 0;
>> > 66   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#66>/**
>> Time to serve records after expiration */
>> > 67   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#67>THREAD
>> <https://indexing2.f5net.com/source/s?defs=THREAD&project=tmos-dns-bugs>
>> time_t  <
>> https://indexing2.f5net.com/source/s?defs=time_t&project=tmos-dns-bugs>
>> SERVE_EXPIRED_TTL  <
>> https://indexing2.f5net.com/source/s?refs=SERVE_EXPIRED_TTL&project=tmos-dns-bugs>
>> = 0;
>> > 68   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#68>/**
>> TTL to use for expired records */
>> > 69   <
>> https://indexing2.f5net.com/source/xref/tmos-dns-bugs/ports/unbound/build/util/data/msgreply.c#69>THREAD
>> <https://indexing2.f5net.com/source/s?defs=THREAD&project=tmos-dns-bugs>
>> time_t  <
>> https://indexing2.f5net.com/source/s?defs=time_t&project=tmos-dns-bugs>
>> SERVE_EXPIRED_REPLY_TTL  <
>> https://indexing2.f5net.com/source/s?refs=SERVE_EXPIRED_REPLY_TTL&project=tmos-dns-bugs>
>> =30;
>> >
>> >
>> > Thanks,
>> >
>> > Ashok
>> >
>>
>
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