Don't look for IP v6 addresses if no IP v6 support complied into PHP

[walec51]

Closes #33567

[Altahrim]

Well spotted :)

I think it would be better to avoid AAAA lookup if IPv6 isn't supported.
Something like this on line 78:

$dnsTypes = defined('AF_INET6') 
	? [DNS_A, DNS_AAAA, DNS_CNAME]
	: [DNS_A, DNS_CNAME];

[kesselb]

The php constant AF_INET6 is only defined when php-sockets is enabled: https://github.com/php/php-src/blob/36b194ba299467f075e5c1ce546164702c56938a/ext/sockets/sockets_arginfo.h#L342

I assume, because the module is enabled by default, that's the case for most system packages, but we don't list sockets as required php module on https://docs.nextcloud.com/server/latest/admin_manual/installation/source_installation.html#prerequisites-for-manual-installation.

If we depend on it, we should add it there as well.

[georglauterbach]

What's the progress on this?

In my cluster, coreDNS logs 39200 "AAAA IN <POSTGRES DNS NAME> udp 44 false 512" NOERROR qr,aa,rd 119 0.000177098s every 3 or 4 seconds, which is extremely annoying and, quite frankly, unnecessary.

On a side note: Marking and locking the corresponding issue #33567 as "too heated", when people are simply complaining (without any "heat" involved), does not help anyone. Instead, it shows how little is cared in this case, which, I think, is sad, more than anything else.

[Altahrim]

We can detect IPv6 with inet_pton.

Following my previous comment it could be:

$dnsTypes = inet_pton('::1') === false
	? [DNS_A, DNS_CNAME]
	: [DNS_A, DNS_AAAA, DNS_CNAME];