SecurityManager s = System.getSecurityManager(); if (s != null && isConnected ()) s.checkAccept (p.getAddress().getHostName (), p.getPort ());
  public synchronized void receive(DatagramPacket p) throws IOException  {    SecurityManager s = System.getSecurityManager();    if (s != null)      s.checkAccept (p.getAddress().getHostName (), p.getPort ());		     if (impl == null)      throw new IOException ("Cannot initialize Socket implementation");    if (ch != null && !ch.isBlocking ())      throw new IllegalBlockingModeException ();    impl.receive(p);  }