} elsif (my $host = param('host')) { # returning to select host
  if ($host =~ /^([a-zA-Z0-9.\-]{1,100})\z/) { # create a session
    $host = $1;                 # untainted now
    print h1("Yes"); # The line I added, only thing I changed.
    my $session = get_session_id();
    my $cache = get_cache_handle();
    $cache->set($session, [0, ""]); # no data yet