sub check_url {
        local $_ = shift;
        my $valid_referrers = shift;

        my $valid = join '|', @$valid_referrers;
        return /$valid/ ? 1 : 0;
    }

##</code><code>##

    my @referrers =
       ('http://www.foo.com/',
        'http://www.bar.com/');

    my @urls_to_check = 
       ('http://www.baz.com/bar/',
        'http://www.foo.com/bar/');

    for my $url (@urls_to_check) {
        print $url, ": ", check_url($url, \@referrers), "\n";
    }