Question

Is it possible to check a string with a single regex and validate it if matches valid IPv4 or IPv6 address or even a hostname with no special characters but dot (.)?

I have separate regex for IPv4 and IPv6 but how do I combine them to do the work described above?

Thanks in advance,

Dan

Answer 1

You could use a single regex, but it’s going to be ugly as hell. Either;

• Create separate regexes as strings, then combine them. Far more legible. Or,
• Test each regex separately. Also much clearer.

Perl-ish example:

if ( $foo =~ /$ipv4_re/ or $foo =~ /$ipv6_re/ or $foo =~ /$hostname_re/ ) {
    ...
}

Having said that, there are probably libraries in Python that will validate these things for you, and personally I’d rather rely on them.