[rbldnsd] Warning: possible danger of using rbldnsd, and upcoming data format change

[Matthew Sullivan]

David Landgren wrote:

> Matthew Sullivan wrote:
>
>> 1/ rbldnsd check for and create a lockfile (similar to the old Serial 
>> Port lockfiles) - if it's present and locked (exclusive), rbldnsd 
>> would not open/update the zonefiles.  If the lockfile was present and 
>> locked for exclusive use, then any update program would be made not 
>> to update the files.... Of course you could lock the zonefiles 
>> themselves for exclusive access and lockout things like rsync.
>
>
> You have traded one problem for another. Now you have to deal with 
> stale locks.
>
> The main problem appears to be idi^H^H^Hpeople who attempt to upload 
> data files directly into production. Madness! Inter-system file 
> transfers should always use store-and-forward techniques, where the 
> receiving end can run sanity checks to make sure the file is correct, 
> before moving it over into production.
>
> Having an end-of-file marker on the last line of the file is perfect 
> for this.
>
> One should always be wary of encumbering an application with 
> unnecessary cruft to solve a (non-)problem that should be addressed by 
> basic rules of hygiene.


EOF will not help you then have a race condition where the daemon opens 
for reading, and something opens for writing...

/ Mat