partial NTP

uint32_t g_networkClockSyncTS = 0;
time_t networkReceiveNTPTime() {
  // if we got a packet from NTP, read it
  if (0 < g_networkUDP.parsePacket()) {
    g_networkUDP.read(g_networkNTPPacketBuffer, NTP_PACKET_SIZE); // read the packet into the buffer

    //the timestamp starts at byte 40 of the received packet and is four bytes,
    // or two words, long. First, extract the two words:

    unsigned long highWord = word(g_networkNTPPacketBuffer[40], g_networkNTPPacketBuffer[41]);
    unsigned long lowWord = word(g_networkNTPPacketBuffer[42], g_networkNTPPacketBuffer[43]);
    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
    // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
    const unsigned long seventyYears = 2208988800UL;
    // subtract seventy years:
    return secsSince1900 - seventyYears;
  }
  return 0;
}
// send an NTP request to the time server
void networkSendNTPPacket() {
  IPAddress ntpIP;
  WiFi.hostByName(NTP_SERVER, ntpIP);
  // set all bytes in the buffer to 0
  memset(g_networkNTPPacketBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  g_networkNTPPacketBuffer[0] = 0b11100011;   // LI, Version, Mode
  g_networkNTPPacketBuffer[1] = 0;     // Stratum, or type of clock
  g_networkNTPPacketBuffer[2] = 6;     // Polling Interval
  g_networkNTPPacketBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  g_networkNTPPacketBuffer[12]  = 49;
  g_networkNTPPacketBuffer[13]  = 0x4E;
  g_networkNTPPacketBuffer[14]  = 49;
  g_networkNTPPacketBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  g_networkUDP.beginPacket(ntpIP, 123); //NTP requests are to port 123
  g_networkUDP.write(g_networkNTPPacketBuffer, NTP_PACKET_SIZE);
  g_networkUDP.endPacket();
}
void beginNetworkClock() {
  beginNetworkUDP();
}
void networkSyncClock() {
  if (WL_CONNECTED == WiFi.status()) {
    uint32_t ms = millis();
    if (ms - g_networkClockSyncTS > (1000 * NTP_SYNC_FREQUENCY)) {
      g_networkClockSyncTS = ms;
      networkSendNTPPacket();
    }
    time_t t = networkReceiveNTPTime();
    if (0 != t)
      clockSet(t);
  }
}