opnsense
dns/rfc2136: Do DNS request additionally or instead of cachedipv4 variable
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Is your feature request related to a problem? Please describe.
When the DNS record which the rfc2136 plugin is handling is changed somehow from somewhere else, I experienced that the plugin will not notice this at all. Hence, the IP will remain wrong for probably 25 days according to the hard coded $maxCacheAgeSecs variable.
I have read through rfc2136.inc and it looks to me that the plugin only considers $cachedipv4, which in turn it takes internally from the interface or by an external request to determine the IP address. I think it never checks the actual currently set A record of the NS in question.
Describe the solution you'd like
One could simply add a DNS request on the hostname we want to handle and put it in a variable like $currentdnsrecord. Compare $currentdnsrecord with $wanip here https://github.com/opnsense/plugins/blob/bea60a2883fb81a2fb213e98899265e477fa003b/dns/rfc2136/src/etc/inc/plugins.inc.d/rfc2136.inc#L157C1-L158C1 should then effectively resynchronize what dns/rfc2136 believes the IP is and what the rest of the world sees.
I have this exact approach running on a shell script which worked well for years. I could work on a PR implementing this here in the plugin, however, before I put in the time I would like to give maintainers a chance to chime in on whether this approach is even acceptable to them.
Describe alternatives you've considered
I tried OPNsense cronjob running "RFC 2136 Update" to force an update, however, this seems to remain without effect. I suppose because only $cachedipv4 and the current IP in $wanip are considered, but not what the DNS server has set as an A record for the hostname in question.
