Validate preg_replace domain

Question

My question is this, I have the following function:

$site = preg_replace("/[^a-zA-Z0-9]/", "", $_POST['site']);

But when using in the string www.lostscavenge.com.br, that regular expression emits the following return: wwwlostscavengecombr

How do I allow and not remove points?

Answer 1

Domain names may currently be Unicode (utf8). Depending on the rules of your business model, if you need to allow domains that have non-ASCII characters, the following routine may be useful:

function validate_domain_name($str, $force_utf8 = true)
{
    $force_utf8 = $force_utf8? 'u': '';

    //Isso é ineficiente.
    //$re = '[^a-zA-Z0-9\.]';

    //Isso é ineficiente. Pois não valida normas básicas
    //$re = '^(http[s]?\:\/\/)?((\w+)\.)?(([\w-]+)?)(\.[\w-]+){1,2}$';

    //Esse é mais consistente
    $re = '^(?!\-)(?:[\w\d\-]{0,62}[\w\d]\.){1,126}(?!\d+)[\w\d]{1,63}$';

    if (preg_match('/'.$re.'/'.$force_utf8, $str, $rs) && isset($rs[0]) && !empty($rs[0])) {
        return $rs[0];
    } else {
        return null;
    }
}

$str = '000-.com';
$str = '-000.com';
$str = '000.com'; // válido
$str = 'foo-.com';
$str = '-foo.com';
$str = 'foo.com'; // válido
$str = 'foo.any'; // válido
$str = 'お名前0.com'; // válido
$str = 'お名前.コム'; // válido

echo 'domain: '.validate_domain_name($str);

To disable Unicode, set the second parameter to boolean false.

The original regular expression has been adapted from this response: https://stackoverflow.com/a/16491074/1685571

The adaptations I made were changing a-zA-Z for \w and add the option to include the flag u, which allows non-ASCII characters.

Answer 2

Just add the stitch to your pattern:

$site = preg_replace("/[^a-zA-Z0-9\.]/", "", $_POST['site']);

Is that \. at the end of the pattern. A \ is to escape the point (.), because in regular expressions the . means any character