[ldns-users] ldns & TTL

[Willem Toorop]

Andreas,

Thanks for the references!

Op 25-11-2021 om 11:20 schreef A. Schulze:
> so I think, any implementation should
> 
>  - reject negative values as input -> fail/error

Agree.

>  - convert any positive input larger then 2^31 - 1 as zero -> silent or with warning

I don't know.  I think it should at least be possible to create such
records with ldns, maybe with a "force" (-F) option?  And without that
option produce warnings (if above a certain verbosity level).

The "force" (-F) option might also be usable to deal (accept) high NSEC3
iteration counts perhaps.

>  - only use 0 <= TTL <= 2^31 - 1 as output

Again I'm not sure.  I would prefer to print that what was in the wire
data with least interference.  But maybe we could in this case have some
sort of "fix" or "strict" option?

I do think anything like this should be postponed till after the 1.8.0
release though.  But, please keep the discussion and suggestions going
(if only to keep momentum) and then let's have a 1.8.1 release with the
outcome of that soonish, okay?

Cheers,
-- Willem

> 
> right?
> 
> Andreas
> 
> 
> 
> 
>>
>> Cheers,
>> -- Willem
>>
>> Op 24-11-2021 om 17:05 schreef Willem Toorop via ldns-users:
>>> Hi Andreas,
>>>
>>> Op 24-11-2021 om 16:54 schreef A. Schulze via ldns-users:
>>>> Hello,
>>>>
>>>> in a discussion about valid TTL values I noted unexpected output while feeding different TTL into ldns-read-zone.
>>>>
>>>> To reproduce use something like this:
>>>> TTL=$( echo 'value' | bc ); echo "foo $TTL TXT \"TTL=$TTL\"" | ldns-read-zone 
>>>>
>>>> value       output
>>>> ------------------------------------------------------------------
>>>> 2^31 - 1    foo.    2147483647      IN      TXT     "TTL=2147483647"
>>>> 2^31        foo.    -2147483648     IN      TXT     "TTL=2147483648"
>>>> 2^31 + 1    foo.    -2147483647     IN      TXT     "TTL=2147483649"
>>>>
>>>> 2^32 - 1    foo.    -1              IN      TXT     "TTL=4294967295"
>>>> 2^32        foo.    0               IN      TXT     "TTL=4294967296"
>>>> 2^32 + 1    foo.    1               IN      TXT     "TTL=4294967297"
>>>>
>>>> RFC 1035 define a TTL as "positive values of a signed 32 bit number"
>>>> which mean to me, anything larger then 2^31 - 1 is invalid.
>>>
>>> There has been an errata (in 2012) changing this to an unsigned 32 bit
>>> number: https://www.rfc-editor.org/errata/eid2130
>>>
>>> So ldns is printing it wrong! I'll fix that.
>>> Just in time for the 1.8.0 release!
>>>
>>> Thanks,
>>> -- Willem
>>>
>>>
>>>>
>>>> Could the readers please clarify about
>>>>  - the maximum value per RFC
>>>>  - whether these output of ldns-read-zone is correct
>>>>
>>>> Btw: I used ldns-1.8.0-rc.2
>>>>
>>>> Thanks,
>>>> Andreas
>>>>
>>>>
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