ESP32 ensure SNTP sync enabled before waiting

Signed-off-by: Sara Damiano <[email protected]>

src/TinyGsmClientESP32.h

@@ -401,7 +401,16 @@ class TinyGsmESP32 : public TinyGsmEspressif<TinyGsmESP32>,
   }
 
   bool waitForTimeSync(int timeout_s = 120) {
+    // if we're not connected, we'll never get the time
     if (!isNetworkConnected()) { return false; }
+    // if SNTP sync isn't enabled, we won't have the time
+    // NOTE: We don't actually enable the time here, because doing so would
+    // change any user settings for the timezone and time servers.
+    sendAT(GF("+CIPSNTPCFG?"));
+    int8_t is_enabled = streamGetIntBefore(',');
+    waitResponse();  // returns OK
+    if (!is_enabled) { return false; }
+    // if we're sure we should be able to get the time, wait for it
     uint32_t start_millis = millis();
     while (millis() - start_millis < static_cast<uint32_t>(timeout_s) * 1000) {
       uint32_t modem_time = getNetworkEpoch();