Check Timezone offset boundaries

Author: pennam

src/utility/time/TimeService.cpp

@@ -103,7 +103,7 @@ TimeServiceClass::TimeServiceClass()
 : _con_hdl(nullptr)
 , _is_rtc_configured(false)
 , _is_tz_configured(false)
-, _timezone_offset(0)
+, _timezone_offset(24 * 60 * 60)
 , _timezone_dst_until(0)
 , _last_sync_tick(0)
 , _sync_interval_ms(TIMESERVICE_NTP_SYNC_TIMEOUT_ms)
@@ -184,11 +184,13 @@ void TimeServiceClass::setSyncFunction(syncTimeFunctionPtr sync_func)
 
 void TimeServiceClass::setTimeZoneData(long offset, unsigned long dst_until)
 {
-  if(_timezone_offset != offset || _timezone_dst_until != dst_until) {
-    DEBUG_DEBUG("TimeServiceClass::%s offset: %d dst_unitl %ul", __FUNCTION__, offset, dst_until);
-    _timezone_offset = offset;
-    _timezone_dst_until = dst_until;
-    _is_tz_configured = true;
+  if(isTimeZoneOffsetValid(offset) && isTimeValid(dst_until)) {
+    if(_timezone_offset != offset || _timezone_dst_until != dst_until) {
+      DEBUG_DEBUG("TimeServiceClass::%s offset: %d dst_unitl %u", __FUNCTION__, offset, dst_until);
+      _timezone_offset = offset;
+      _timezone_dst_until = dst_until;
+      _is_tz_configured = true;
+    }
   }
 }
 
@@ -312,6 +314,12 @@ bool TimeServiceClass::isTimeValid(unsigned long const time)
   return (time > EPOCH_AT_COMPILE_TIME);
 }
 
+bool TimeServiceClass::isTimeZoneOffsetValid(long const offset)
+{
+  /* UTC offset can go from +14 to -12 hours */
+  return ((offset < (14 * 60 * 60)) && (offset > (-12 * 60 * 60)));
+}
+
 void TimeServiceClass::initRTC()
 {
 #if defined (ARDUINO_ARCH_SAMD)

src/utility/time/TimeService.h

@@ -74,6 +74,8 @@ class TimeServiceClass
   void initRTC();
   void setRTC(unsigned long time);
   unsigned long getRTC();
+  static bool isTimeValid(unsigned long const time);
+  static bool isTimeZoneOffsetValid(long const offset);
 
 };