+/*
+ * np_up - a network protocol has come up.
+ */
+void
+np_up(unit, proto)
+ int unit, proto;
+{
+ if (num_np_up == 0 && idle_time_limit > 0) {
+ TIMEOUT(check_idle, NULL, idle_time_limit);
+ }
+ ++num_np_up;
+}
+
+/*
+ * np_down - a network protocol has gone down.
+ */
+void
+np_down(unit, proto)
+ int unit, proto;
+{
+ if (--num_np_up == 0 && idle_time_limit > 0) {
+ UNTIMEOUT(check_idle, NULL);
+ }
+}
+
+/*
+ * np_finished - a network protocol has finished using the link.
+ */
+void
+np_finished(unit, proto)
+ int unit, proto;
+{
+ if (--num_np_open <= 0) {
+ /* no further use for the link: shut up shop. */
+ lcp_close(0);
+ }
+}
+
+/*
+ * check_idle - check whether the link has been idle for long
+ * enough that we can shut it down.
+ */
+static void
+check_idle(arg)
+ caddr_t arg;
+{
+ struct ppp_idle idle;
+ time_t itime;
+
+ if (!get_idle_time(0, &idle))
+ return;
+ itime = MIN(idle.xmit_idle, idle.recv_idle);
+ if (itime >= idle_time_limit) {
+ /* link is idle: shut it down. */
+ syslog(LOG_INFO, "Terminating connection due to lack of activity.");
+ lcp_close(0);
+ } else {
+ TIMEOUT(check_idle, NULL, idle_time_limit - itime);
+ }
+}
+