PHP - Using preg_replace to put http:// before link

Question

I have a bbCode function I made:

function bbCode($str)
{
    $values = array(
      '@\[link="(.*?)"\](.*?)\[\/link\]@i' => '<a href="$1">$2</a>'

    );
    return preg_replace(array_keys($values), array_values($values), $str);
}

It works well but if the user types, for example [link="google.com"]Something[/link], the result would be

<a href="google.com">Something</a>

And that would return to www.mywebsite.com/google.com How could I prevent this from happening?

Answer 1

You can prefix it with http://

function bbCode($str)
{
$values = array(
  '@\[link="[http:\/\/]*(.*?)"\](.*?)\[\/link\]@i' => '<a href="http://$1">$2</a>'
);
return preg_replace(array_keys($values), array_values($values), $str);
}

Answer 2

I think you should check for a valid URL this way:

function bbCode($str)
{   
    $new = preg_replace_callback('@\[link="(.*?)"\](.*?)\[\/link\]@i', function($matches){
        $url = $matches[1] ;
        $text = $matches[2] ;

        if (filter_var($url, FILTER_VALIDATE_URL) === FALSE){
            $url = "http://{$url}" ;
        }

        return "<a href='{$url}'>{$text}</a>" ;
    }, $str);

    return $new ;
}


$code = '[link="google.com"]TEXT[/link]' ;
echo bbCode($code) ;