Update of valid hostnames Regex

[brenner-tobias]

While trying to allow domain names to include Umlaute, we realized that the current regex for validation if not that simple and could be improved.

Current version:

^(([a-z0-9äöüß]|[a-z0-9äöüß][a-z0-9äöüß\-]*[a-z0-9äöüß])\.)*([a-z0-9]|[a-z0-9][a-z0-9\-]*[a-z0-9])$

One suggestion is to change it to:

^((\w|\w[\w\-]*\w)\.)*(\w|\w[\w\-]*\w)$

I would go one step further and change one * to a +, since we do definitely need one "." in the domain name (if I am not mistaken). So the string would look like this:

^((\w|\w[\w\-]*\w)\.)+(\w|\w[\w\-]*\w)$

Any input on these ideas and also tests on regex101 with the above mentioned expression are very much appreciated.

[brenner-tobias]

Thanks a lot @skipishere, @acshef, @flufftronix, @MrAnonymous722 and @elcajon for your input

[brenner-tobias]

Closing this for now, let's keep the current version