Figuring out a referrer

[zzz]

I've noticed that some sites borrow content from my site. I'd like to be able to put out a special message for visitors that come from that site. Is there a way to detect it accurately? I can probably find out the site's IP address and I know the domains already.

[NogDog]

You can check to see if $SERVER['REMOTE_HOST'] or $SERVER['REMOTE_ADDR'] matches that host name or IP address, respectively.

[ucffool]

$SERVER['HTTP_REFERER'] gives you the site that they came from if they clicked a link.
I use the following code to convert that to just: domain.com or subdomain.domain.com but will remove any www.

	$url = $_SERVER['HTTP_REFERER'];
	$hostname = parse_url($url, PHP_URL_HOST);
	// Reduce the hostname to simply subdomain.domain.extension
	$array = array_splice(explode('.',$hostname),-3);
	if ($array[0] == 'www'){ unset($array[0]); }
	$hostname = implode('.', $array);