How does the NTP time synchronization mechanism calibrate round-trip latency jitter against Xiaomi auth gateways?

[PrinceBad]

When dispatching bootloader unlock authorization payloads at exact millisecond boundaries, how does the UDP socket layer measure and adjust for network RTT drift?

[PrinceBad]

NTP Socket Jitter Calibration Strategy

1. UDP Socket Time Probing:
   Before the unlock window opens, the client issues 5-10 lightweight UDP NTP packets to authoritative time servers (e.g., time.google.com or pool.ntp.org) calculating both:
   $$\text{Offset} = \frac{(T_2 - T_1) + (T_3 - T_4)}{2}$$
   $$\text{RTT} = (T_4 - T_1) - (T_3 - T_2)$$

2. HTTP Keep-Alive Pre-Warming:
   TLS handshakes and TCP handshakes to sgp-api.buy.mi.com are completed in advance over persistent keep-alive sessions, eliminating variable 120-250ms connection latency spikes.

3. Sub-Millisecond High-Resolution Dispatch:
   Using time.perf_counter_ns(), request dispatch fires at $T_{\text{target}} - \frac{\text{RTT}_{\text{mean}}}{2}$, arriving at the server precisely when the epoch authorization gate opens.