# source: fd_board.cgi (with modifications)
sub check_url {
   my @referers = (www.hello.com. hello.com);

   if ( (!$ENV{'HTTP_REFERER'}) ||
        (!$ENV{'CONTENT_LENGTH'}) ||
        (!$ENV{'HTTP_ACCEPT'}) ||
        (!$ENV{'HTTP_USER_AGENT'})) {
   	  &error('bad_headers');
   }

   my $check_referer = 0;

   foreach my $referer (@referers) {
	if ($ENV{'HTTP_REFERER'} =~ m|https?://([^/]*)$referer|i) {
		$check_referer = 1;
		last;
	}
   }

   if ($check_referer != 1) {
	&error('bad_referer')
   }
}