Re: [Ddclient-support] ddclient improvement suggestion.

[Paul N. P. <pau...@gm...>]

I can only imagine the joyous times involved in uncovering such a bug.

On Thu, Jan 1, 2015 at 11:47 AM, balthasar_s <
bic...@ch...> wrote:

> ddclient won't update the IP until a minimal interval since last update.
> Very good. But the way it's implemented now can lead to problems in
> specific circumstances.
>
> For example. It's 2015. But the system clock is erroneously set to
> 2020 (because of problems with NTP or something else). Then ddclient
> runs and remembers in the cache that the last run was in 2020. After
> the system clock is (automatically) set back to 2015, ddclient becomes
> non-functional. It will refuse to update the IP because the 5 minute
> (or whatever else) interval since 2020 has not passed yet. Until 2020
> ddclient won't update anything unless the cache is removed.
> This is problematic because when you notice that you have to fix it
> and remove the cache it's too late because the IP changed, was not
> updated and you don't have access to your computer.
>
> This can be easily improved. Instead of checking the time distance
> into the future check the time distance in both directions. To do so
> replace one line in the interval_expired function.
>
>
> Change this:
>
> sub interval_expired {
>     my ($host, $time, $interval) = @_;
>
>     return 1 if !exists $cache{$host};
>     return 1 if !exists $cache{$host}{$time}      || !$cache{$host}{$time};
>     return 1 if !exists $config{$host}{$interval} ||
> !$config{$host}{$interval};
>
>     return $now > ($cache{$host}{$time} + $config{$host}{$interval});
> }
>
> to this:
>
> sub interval_expired {
>     my ($host, $time, $interval) = @_;
>
>     return 1 if !exists $cache{$host};
>     return 1 if !exists $cache{$host}{$time}      || !$cache{$host}{$time};
>     return 1 if !exists $config{$host}{$interval} ||
> !$config{$host}{$interval};
>
>     return ($now > ($cache{$host}{$time} + $config{$host}{$interval}))
> || ($now < ($cache{$host}{$time} - $config{$host}{$interval}));
> }
>
>
> that's all.
>
>
> Balthasar Szczepański
>
>
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