Check if URL is from a certain website

Question

Problem

The user can submit a form where he can submit a link to sitea.com. Now what I want to do is check if the user actually submitted an URL coming fr

Answer 1

I think it's best parse_url() here. Regex may work, but it's best to avoid using regex when a built-in function is available.

I'd do something like:

$url = '...';
$domain = implode('.', array_slice(explode('.', parse_url($url, PHP_URL_HOST)), -2));

if ($domain == 'sitea.com') {
    # code...
}

As a function:

function getDomain($url) 
{
    $domain = implode('.', array_slice(explode('.', parse_url($url, PHP_URL_HOST)), -2));
    if ($domain == 'sitea.com') {
        return True;
    } else {
        return False;
    }

}

Test cases:

var_dump(getDomain('http://sitea.com/'));
var_dump(getDomain('http://sitea.com/directory'));
var_dump(getDomain('http://subdomain.sitea.com/'));
var_dump(getDomain('http://sub.subdomain.sitea.com/#test'));

var_dump(getDomain('http://subdomain.notsitea.com/#dsdf'));
var_dump(getDomain('http://sitea.somesite.com'));
var_dump(getDomain('http://example.com/sitea.com'));
var_dump(getDomain('http://sitea.example.com/test.php?haha=sitea.com'));

Output:

bool(true)
bool(true)
bool(true)
bool(true)

bool(false)
bool(false)
bool(false)
bool(false)

Demo!

Answer 2

This might not be a job for regexes, but for existing tools in your language of choice. Regexes are not a magic wand you wave at every problem that happens to involve strings. You probably want to use existing code that has already been written, tested, and debugged.

In PHP, use the parse_url function.

Perl: URI module.

Ruby: URI module.

.NET: 'Uri' class