Why does checkdnsrr() default to MX?? View as Markdown

Hey guys,

I just spent some time troubleshooting what appeared to be a DNS issue
before I realized that, absent the optional $type argument, checkdnsrr()
defaults to "MX". Can anybody explain why it's defaulting to "MX" and
not
"ANY"? It seems really counter-intuitive.

This is a big wtf, especially since getmxrr() exists. A cursory search
of github (not the best measure I know, but easy) reveals only a few
cases where this function is called without the second argument, and
every case I've found looks like they were expecting an A record, so
this code is likely broken anyway.

In other words, +1 to change this to something saner ASAP.

As an alternative, could we just make the type argument mandatory in
PHP 7 and start issuing E_DEPRECATED warnings if it's omitted in 5.6
or 5.7?

Adam

I like both ideas. Adam's approach would be more inconvenient for
developers, but it would also be less of a BC issue since merely changing
the default could cause some existing code to fail silently as opposed to
generating an error. On the other hand, I can't think of any such use case
in which checking all DNS entries instead of just MX would cause any
scripts to break. The only possible scenario I can think of would be if
they're using dnsrr() to check if an MX record exists and hit a host that
has an A record but not MX. That would cause it to return TRUE when
they're expecting FALSE.

I'll draft an RFC when I get a chance and include both options in it.

--Kris