Function readNtpTimestamp

ntp/ntp.ts:59–66

(buf: Buffer, offset: number)

  const ms = (sec - NTP_EPOCH_OFFSET) * 1000 + Math.floor((frac / 2 ** 32) * 1000);
  return ms;
}

async function queryOnce(host: string, timeoutMs = 2500): Promise<NtpResult> {
  return new Promise((resolve, reject) => {
    const socket = dgram.createSocket("udp4");
    let timeoutTimer: NodeJS.Timeout | null = null;

    const packet = Buffer.alloc(48);
    // LI = 0 (no warning), VN = 4, Mode = 3 (client) -> 0b00 100 011 = 0x23
    packet[0] = 0x23;
    // Transmit timestamp: set to client time (optional but good practice)