async def _poller(self):
self._status = 0
while True:
# print("\nperforming NTP query")
try:
self.status = (self._status << 1) & 0xFFFF
(delay_us, step_us) = await self._poll()
if step_us > self._max_step or -step_us > self._max_step:
# large adjustment: step the clock, don't slew
# print(time.localtime())
(tgt_s, tgt_us) = divmod(time.time_us() + step_us, 1000000)
log.warning("stepping to %s", time.localtime(tgt_s))
settime(tgt_s, tgt_us)
# print(time.localtime())
# if the adjustment is too small WRT round-trip delay, it's likely not to be
# very good and result in lots of noise, so skip
elif step_us > 2 * delay_us or -step_us > 2 * delay_us:
lvl = logging.DEBUG if abs(
step_us) < 10000 else logging.INFO
log.log(lvl, "adjusting by %dus (delay=%dus)", step_us,
delay_us)
adjtime(step_us)
self.status |= 1
await asyncio.sleep(61)
except asyncio.TimeoutError:
log.warning("%s timed out", self._host)
if (self._status & 0x7) == 0:
# Three failures in a row, force fresh DNS look-up
self.sock = None
await asyncio.sleep(11)
except OSError as e:
# Most likely DNS lookup failure
log.warning("%s: %s", self._host, e)
self.sock = None
await asyncio.sleep(11)
except Exception as e:
log.error("%s", e)
print_exception(e)
await asyncio.sleep(121)
async def _poller(self):
self._status = 0
while True:
# print("\nperforming NTP query")
try:
self.status = (self._status << 1) & 0xFFFF
(delay_us, step_us) = await self._poll()
if step_us > self._max_step or -step_us > self._max_step:
# print(time.localtime())
(tgt_s, tgt_us) = divmod(time.time_us() + step_us, 1000000)
log.warning("stepping to %s", time.localtime(tgt_s))
settime(tgt_s, tgt_us)
# print(time.localtime())
else:
lvl = logging.DEBUG if abs(
step_us) < 10000 else logging.INFO
log.log(lvl, "adjusting by %dus (delay=%dus)", step_us,
delay_us)
adjtime(step_us)
self.status |= 1
await asyncio.sleep(61)
except asyncio.TimeoutError:
log.warning("%s timed out", self._host)
if (self._status & 0x7) == 0:
# Three failures in a row, force fresh DNS look-up
self.sock = None
await asyncio.sleep(11)
except OSError as e:
# Most likely DNS lookup failure
log.warning("%s: %s", self._host, e)
self.sock = None
await asyncio.sleep(11)
except Exception as e:
log.error("%s", e)
print_exception(e)
await asyncio.sleep(121)
async def _poll(self):
# We try to stay with the same server as long as possible. Only
# lookup the address on startup or after errors.
if self._sock is None:
self._addr = socket.getaddrinfo(self._host, 123)[0][-1]
log.debug("server %s->%s", self._host, self._addr)
if sys.implementation.name == "micropython":
self._sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self._sock.connect(self._addr)
stream = asyncio.StreamReader(self._sock)
async def write_drain(pkt):
stream.write(pkt)
await stream.drain()
self._send = write_drain
self._recv = lambda length: stream.read(length)
self._close = lambda: self._sock.close()
else:
stream = await dgram_connect(self._addr)
async def stream_send(pkt):
return await stream.send(pkt)
self._send = stream_send
async def stream_recv(length):
return (await stream.recv())[0]
self._recv = stream_recv
self._close = lambda: stream.close()
# Send the NTP v3 request to the server
wbuf = bytearray(48)
wbuf[0] = 0b00011011
send_us = time_us()
send_ntp = mp2ntp(send_us)
struct.pack_into("!II", wbuf, OFF_TX, send_ntp[0],
send_ntp[1]) # set tx timestamp
await self._send(wbuf)
# Get server reply
while True:
# Raises asyncio.TimeoutError on time-out
rbuf = await asyncio.wait_for(self._recv(48), timeout=1)
recv_us = time_us()
# Verify it's truly a response to our request
orig_ntp = struct.unpack_from("!II", rbuf,
OFF_ORIG) # get originate timestamp
if orig_ntp == send_ntp:
break
# Calculate clock step to apply per RFC4330
rx_us = ntp2mp(*struct.unpack_from(
"!II", rbuf, OFF_RX)) # get server recv timestamp
tx_us = ntp2mp(*struct.unpack_from(
"!II", rbuf, OFF_TX)) # get server transmit timestamp
delay = (recv_us - send_us) - (tx_us - rx_us)
step = ((rx_us - send_us) + (tx_us - recv_us)) // 2
tup = struct.unpack_from("!IIIIII", rbuf, OFF_ORIG)
r = mp2ntp(recv_us)
# log.debug( "orig=[%d,%x] rx=[%d,%x] tx=[%d,%x] recv=[%d,%x] -> delay=%fms step=%dus",
# tup[0], tup[1], tup[2], tup[3], tup[4], tup[5], r[0], r[1], delay / 1000, step)
return (delay, step)
def adjtime(usecs):
print("adjtime(%d) - an adjustment of %d" % (usecs, time_us() -
(usecs + UNIX_DELTA)))
def settime(usecs):
print("settime(%d) - a step of %d" % (usecs, time_us() -
(usecs + UNIX_DELTA)))