Use compile time timestamp as NTP backup.

examples/opcua_server/opcua_server.ino

@@ -198,6 +198,8 @@ void setup()
   auto const epoch = opcua::NTPUtils::getTime(udp_client);
   if (epoch > 0) {
     set_time(epoch); /* Directly set RTC of Arduino Opta. */
+  } else {
+    set_time(opcua::cvt_time(__DATE__)); /* Configure Arduino Opta with time at compile time as last time of defense. */
   }
 
   /* Initialize heap memory. */

src/Arduino_open62541.h

@@ -16,6 +16,7 @@
 #include "open62541.h"
 #include "o1heap/o1heap.h"
 #include "NTPUtils.h"
+#include "cvt_time.h"
 
 #include "ArduinoOpta.h"
 #include "ArduinoOptaVariant.h"

src/cvt_time.cpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2024 Arduino
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include "cvt_time.h"
+
+#include <stdio.h>
+#include <string.h>
+
+/**************************************************************************************
+ * NAMESPACE
+ **************************************************************************************/
+
+namespace opcua
+{
+
+/**************************************************************************************
+ * FUNCTION DEFINITION
+ **************************************************************************************/
+
+time_t cvt_time(char const * time)
+{
+  static time_t build_time = 0;
+
+  if (!build_time) {
+    char s_month[5];
+    int month, day, year;
+    struct tm t =
+      {
+        0 /* tm_sec   */,
+        0 /* tm_min   */,
+        0 /* tm_hour  */,
+        0 /* tm_mday  */,
+        0 /* tm_mon   */,
+        0 /* tm_year  */,
+        0 /* tm_wday  */,
+        0 /* tm_yday  */,
+        0 /* tm_isdst */
+      };
+    static const char month_names[] = "JanFebMarAprMayJunJulAugSepOctNovDec";
+
+    sscanf(time, "%s %d %d", s_month, &day, &year);
+
+    month = (strstr(month_names, s_month) - month_names) / 3;
+
+    t.tm_mon = month;
+    t.tm_mday = day;
+    t.tm_year = year - 1900;
+    t.tm_isdst = -1;
+
+    build_time = mktime(&t);
+  }
+
+  return build_time;
+}
+
+/**************************************************************************************
+ * NAMESPACE
+ **************************************************************************************/
+
+} /* opcua */

src/cvt_time.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2024 Arduino
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include <time.h>
+
+/**************************************************************************************
+ * NAMESPACE
+ **************************************************************************************/
+
+namespace opcua
+{
+
+/**************************************************************************************
+ * FUNCTION DECLARATION
+ **************************************************************************************/
+
+time_t cvt_time(char const * time);
+
+/**************************************************************************************
+ * NAMESPACE
+ **************************************************************************************/
+
+} /* opcua */