Referer redirect txt file

I have this code for referer redirect:

<?
$referrer = $_SERVER['HTTP_REFERER'];
if (preg_match("/outsidesite.com/",$referrer)) {
header('Location: http://www.mysite1.com');
}
else {
header('Location: http://www.mysite.com');
};
?>

But the question is:
If I want to match a LIST OF SITES stored on a txt file, insted of "outsidesite.com".
How can I work with a txt list of sites: "mysites.txt"
instead of only one site: "outsidesite.com"

<?
$referrer = $_SERVER['HTTP_REFERER'];
if (preg_match("HERE A TXT WITH A LIST OF SITES mysites.txt",$referrer)) {
header('Location: http://www.mysite1.com');
}
else {
header('Location: ht*tp://www.mysite.com');
};
?>


Anyone knows what to put here: ("HERE A TXT WITH A LIST OF SITES mysites.txt"), to make it functional.
Thanks.

 

I am working with this:

$file=file_get_contents("file.txt");

if (preg_match ("/$file/", ...........

But it only retrives the first value in the txt file, not the second line.
How can I retrive all values, and then call $file?
thank you.