[Url validator] Returns false for valid (and existing) url

[kptLucek]

Symfony version(s) affected: 4.3.2 (propably earlier versions too)

Description
Url validator returns false (invalid url) on valid, and existing url - pattern issue

How to reproduce
Simply get an validator instance, and validate string/model with Url validator.
Url must contain underscores _ (im amazed to see them in url tho)

$url        = 'http://www.cku_zsr_glubczyce.wodip.opole.pl';
$violations = $this->validator->validate(['url' => $url], [
    new Collection([
        'fields' => [
            'url' => [new Url()]
        ]
    ])
]);
if ($violations->count() > 0) {
/** @var ConstraintViolation $violation */
foreach ($violations as $violation) {
    echo $violation->getPropertyPath() . ' :: ' . $violation->getMessage() . "\n";
}

Possible Solution
Update pattern in validator :)

Additional context

[Tobion]

Can you resolve the url?

https://stackoverflow.com/questions/2180465/can-domain-name-subdomains-have-an-underscore-in-it

[kptLucek]

@Tobion what do you mean?

The url i have provided is a string i want to validate, i have service that does collect alot of data by school-type facilities, and url (like one above) is one of properties i do collect.

Everything is verified, and given url is valid, exists, and may be visited (GET to this url returns valid 200 HTTP response).

All i need is to verify if given "string" is "url" (which should be done by Url validator, but is not in given case).

Link from above shows that subdomain(s) with underscore (_) in their name are very common, however for those validator returns violation.

[javiereguiluz]

There are several things to consider:

• If you visit the given http://www.cku_zsr_glubczyce.wodip.opole.pl/ URL, you can browse the website ... so "it doesn't matter" if some RFC says this is not valid. It is a "valid" URL. At least it's a working URL.
• The custom pattern used by Symfony's UrlValidator.php (https://github.com/symfony/symfony/blob/4.4/src/Symfony/Component/Validator/Constraints/UrlValidator.php) says it's not a valid URL.
• The PHP URL filter also says that it's not valid: https://3v4l.org/uJ6WX