Unable to use domain name with hyphens

[sheehanisageek]

In raising this issue, I confirm the following:

• I have read and understood the contributors guide.
• The issue I am reporting can be replicated.
• The issue I am reporting can be is directly related to the pivpn installer script.
• The issue I am reporting isn't a duplicate (see FAQs, closed issues, and open issues).

Describe the bug
The validDomain function does not permit/validate domains with hyphens.

To Reproduce
Steps to reproduce the behavior:

1. Run installer
2. Select "Use a public DNS" when prompted "Will clients use a Public IP or DNS Name to connect to your server (press space to select)?"
3. Type in any DNS name that includes a hyphen
4. See error

Expected behavior
The validDomain function should permit/validate domains with hyphens.

[sheehanisageek]

Example domain name would be "this.is-a-test.net".

Existing expression does not match domains like the above. Here is the expression I used as a workaround.

(?=^.{4,253}$)(^(?:[a-zA-Z0-9](?:(?:[a-zA-Z0-9\-]){0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$)

Applicable code around line 1548 of the installer. I replaced the if statement with the following PCRE interpreted grep.

echo $domain | grep -P '(?=^.{4,253}$)(^(?:[a-zA-Z0-9](?:(?:[a-zA-Z0-9\-]){0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$)' &> /dev/null

[orazioedoardo]

I've applied your suggestion in the test branch (using Bash's here strings to avoid a pipe).