如何检查php中是否存在url

Question

I'm working on a Symfony 2 project and I'm making a custom constraint to check if an url exist. I checked around and found this:

How can I check if a URL exists via PHP?

The problem is if I try a totally random adresse like www.flskkhfkhsdf.com, it gives me a warning and it stop my code. Is there an other way to do that?

The warning:

Warning: get_headers(): php_network_getaddresses: getaddrinfo failed: No such host is known.

Here is my code:

<?php

namespace AdminBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

Class ContrainteUrlExistValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        $file_headers = get_headers($value);
        if($file_headers[0] == 'HTTP/1.1 404 Not Found') {
            $this->context->buildViolation($constraint->message)
                ->setParameter('%string%', $value)
                ->addViolation();
        }
    }
}

Answer 1

I found a solution that works:

<?php

namespace AdminBundle\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

Class ContrainteUrlExistValidator extends ConstraintValidator
{
    public function validate($url, Constraint $constraint)
    {
        //Vérifie si l'url peut être vide
        if(empty($url)&&$constraint->peutEtreVide)
        {
            return;
        }

        //Pattern pour trouver les url qui commence par http:// ou https://
        $pattern='/^(https?:\/\/)/';

        //Valide l'url et s'assure le preg_match a trouvé un match
        if(filter_var($url, FILTER_VALIDATE_URL)&&!empty(preg_match($pattern, $url, $matches)))
        {
            //Trouve l'host
            $hostname=parse_url($url, PHP_URL_HOST);

            //Tente de trouver l'adresse IP de l'host
            if (gethostbyname($hostname) !== $hostname)
            {
                //Cherche les données de l'entête
                $headers=get_headers($url);

                //Tente de trouver une erreur 404
                if(!strpos($headers[0], '404'))
                {
                    return;
                }
            }
        }

        //Crée une erreur
        $this->context->buildViolation($constraint->message)
                    ->setParameter('%string%', $url)
                    ->addViolation();
    }
}