sk_close(s); s = NULL;
if (s) { sk_close(s); s = NULL; }
static int rlogin_closing(Plug plug, char *error_msg, int error_code,			  int calling_back){    sk_close(s);    s = NULL;    if (error_msg) {	/* A socket error has occurred. */	connection_fatal(error_msg);    }				       /* Otherwise, the remote side closed the connection normally. */    return 0;}