--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-in/shutdown.c	Tue Sep 27 23:00:52 2022 -0800
@@ -0,0 +1,62 @@
+/*
+ * In this module we handle the scenarios of themwi-mncc and/or themwi-mgw
+ * shutting down while we are connected to them.  In both scenarios we
+ * terminate all active calls (graceful disconnect signaling toward SIP
+ * callers and toward whichever ThemWi daemon is still running, if either),
+ * but our themwi-sip-in process itself stays running.  This way once
+ * the other required processes restart, inbound calls will start working
+ * once again, without needing to restart themwi-sip-in.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <syslog.h>
+#include "../include/mncc.h"
+#include "../include/gsm48_const.h"
+#include "call.h"
+
+extern struct call *call_list;
+
+static struct gsm_mncc_cause shutdown_cause = {
+	.coding		= GSM48_CAUSE_CODING_GSM,
+	.location	= GSM48_CAUSE_LOC_PRN_S_LU,
+	.value		= GSM48_CC_CAUSE_NETWORK_OOO,
+};
+
+void
+shutdown_gsm_conn()
+{
+	struct call *call;
+
+	for (call = call_list; call; call = call->next) {
+		call->mncc_state = MNCC_STATE_NO_EXIST;
+		if (call->overall_state != OVERALL_STATE_DEAD_SIP) {
+			call->overall_state = OVERALL_STATE_TEARDOWN;
+			disconnect_tmgw(call);
+			disconnect_sip(call, &shutdown_cause);
+		}
+	}
+}
+
+void
+shutdown_mgw_conn()
+{
+	struct call *call;
+
+	for (call = call_list; call; call = call->next) {
+		call->mgw_state = MGW_STATE_NO_EXIST;
+		call->mgw_xact = 0;
+		if (call->overall_state != OVERALL_STATE_DEAD_SIP) {
+			call->overall_state = OVERALL_STATE_TEARDOWN;
+			disconnect_mncc(call, GSM48_CAUSE_LOC_PRN_S_LU,
+					GSM48_CC_CAUSE_NETWORK_OOO);
+			disconnect_sip(call, &shutdown_cause);
+		}
+	}
+}