use IO::Socket::INET;

sub make_socket
{
  return IO::Socket::INET->new(
      PeerAddr => '127.0.0.1',
      PeerPort => 12345,
      Proto    => 'tcp',
      Blocking => 0, # <=== das wichtige
    );
}

sub read_if_possible
{
  my $socket=shift;
  my $buf;
  my $data='';
  while (sysread($server, $buf, 4096))
  { $data .= $buf; }
  return $data;
}