Aloha poʻe habrauser. I kēia lā makemake wau e kamaʻilio e pili ana i ke kākau ʻana i kāu mea kūʻai NTP maʻalahi. Ma ke kumu, e huli ke kamaʻilio ʻana i ke ʻano o ka ʻeke a pehea e hana ʻia ai ka pane mai ka server NTP. E kākau ʻia ke code ma python, no ka mea, i koʻu manaʻo, ʻaʻohe ʻōlelo maikaʻi aʻe no ia mau mea. E hoʻolohe ka poʻe connoisseurs i ka like o ke code me ka code ntplib - ua "hoʻoulu ʻia" wau e ia.
No laila he aha ka NTP? ʻO NTP kahi protocol no ke kamaʻilio ʻana me nā kikowaena manawa. Hoʻohana ʻia kēia protocol i nā mīkini hou. No ka laʻana, ka lawelawe w32tm ma windows.
Aia he 5 mau mana o ka protocol NTP i ka huina. ʻO ka mua, manaʻo 0 (1985, RFC958) i kēia manawa i manaʻo ʻia he kahiko. Hoʻohana ʻia nā mea hou i kēia manawa, 1st (1988, RFC1059), 2nd (1989, RFC1119), 3rd (1992, RFC1305) a me 4th (1996, RFC2030). Hoʻohālikelike nā ʻano 1-4 me kekahi, ʻokoʻa wale lākou i nā algorithm o nā kikowaena.
Hōʻuluʻulu Pāke
Hōʻailona lele (hōʻailona hoʻoponopono) he helu e hōʻike ana i ka ʻōlelo aʻo lua. ʻO ke ʻano:
- 0 - ʻaʻohe hoʻoponopono
- 1 - ka minuke hope o ka lā he 61 kekona
- 2 - ʻo ka minuke hope o ka lā he 59 kekona
- 3 - hāʻule ka server (ka manawa pau ʻole)
Helu mana (helu helu) – helu mana o ka protocol NTP (1-4).
ano (mode) - ke ʻano hana o ka mea hoʻouna packet. Waiwai mai ka 0 a i ka 7, ka mea maʻamau:
- 3 - mea kūʻai
- 4 - kikowaena
- 5 - ke ʻano hoʻolaha
stratus (layering level) - ka helu o nā papa waena ma waena o ke kikowaena a me ka uaki kuhikuhi (1 - lawe pololei ke kikowaena i ka ʻikepili mai ka uaki kuhikuhi, 2 - lawe ke kikowaena i ka ʻikepili mai ke kikowaena me ka pae 1, etc.).
Pool he helu helu i kau inoa ʻia e hōʻike ana i ka wā lōʻihi ma waena o nā memo. Hōʻike ka mea kūʻai NTP ma aneʻi i ka wā e manaʻo ai e koho i ke kikowaena, a ʻo ke kikowaena NTP e kuhikuhi i ka wā i manaʻo ʻia e koho ʻia. Ua like ka waiwai me ka logarithm binary o kekona.
Ke koho (ka pololei) he integer pūlima e hōʻike ana i ka pololei o ka uaki ʻōnaehana. Ua like ka waiwai me ka logarithm binary o kekona.
lohi aʻa (server latency) ʻo ia ka manawa e hiki ai ka uaki i ke kikowaena NTP, ma ke ʻano he helu mau kekona.
hoʻopuehu aʻa (server scatter) - ʻO ka hoʻopuehu ʻana o ka uaki kikowaena NTP ma ke ʻano he helu paʻa mau kekona.
Ref id (source id) – kiaʻi id. Inā he stratum 1 ka kikowaena, a laila ʻo ref id ka inoa o ka uaki atomic (4 mau huaʻōlelo ASCII). Inā hoʻohana ke kikowaena i kahi kikowaena ʻē aʻe, aia i ka ref id ka helu o kēia kikowaena.
Hōʻike nā māla hope 4 i ka manawa - 32 bits - ka ʻāpana integer, 32 bits - ka hapa hakina.
Reference - ka uaki hou loa ma ke kikowaena.
Hoʻomaka - ka manawa i hoʻouna ʻia ai ka ʻeke (hoʻopiha ʻia e ke kikowaena - ʻoi aku ka nui ma lalo).
E loaʻa - ka manawa i loaʻa ai ka ʻeke e ke kikowaena.
ke hoʻouna i - ka manawa i hoʻouna ʻia ai ka ʻeke mai ke kikowaena i ka mea kūʻai aku (hoʻopiha ʻia e ka mea kūʻai aku, ʻoi aku ka nui ma lalo).
ʻAʻole e noʻonoʻo ʻia nā kahua hope ʻelua.
E kākau kāua i kā mākou pūʻolo:
Code pūʻolo
class NTPPacket:
_FORMAT = "!B B b b 11I"
def __init__(self, version_number=2, mode=3, transmit=0):
# Necessary of enter leap second (2 bits)
self.leap_indicator = 0
# Version of protocol (3 bits)
self.version_number = version_number
# Mode of sender (3 bits)
self.mode = mode
# The level of "layering" reading time (1 byte)
self.stratum = 0
# Interval between requests (1 byte)
self.pool = 0
# Precision (log2) (1 byte)
self.precision = 0
# Interval for the clock reach NTP server (4 bytes)
self.root_delay = 0
# Scatter the clock NTP-server (4 bytes)
self.root_dispersion = 0
# Indicator of clocks (4 bytes)
self.ref_id = 0
# Last update time on server (8 bytes)
self.reference = 0
# Time of sending packet from local machine (8 bytes)
self.originate = 0
# Time of receipt on server (8 bytes)
self.receive = 0
# Time of sending answer from server (8 bytes)
self.transmit = transmit
No ka hoʻouna ʻana (a loaʻa) i kahi ʻeke i ke kikowaena, pono mākou e hoʻololi iā ia i ʻāpana o nā bytes.
No kēia hana (a hoʻohuli), e kākau mākou i ʻelua mau hana - pack() a unpack ():
hana pūʻolo
def pack(self):
return struct.pack(NTPPacket._FORMAT,
(self.leap_indicator << 6) +
(self.version_number << 3) + self.mode,
self.stratum,
self.pool,
self.precision,
int(self.root_delay) + get_fraction(self.root_delay, 16),
int(self.root_dispersion) +
get_fraction(self.root_dispersion, 16),
self.ref_id,
int(self.reference),
get_fraction(self.reference, 32),
int(self.originate),
get_fraction(self.originate, 32),
int(self.receive),
get_fraction(self.receive, 32),
int(self.transmit),
get_fraction(self.transmit, 32))
wehe i ka hana
def unpack(self, data: bytes):
unpacked_data = struct.unpack(NTPPacket._FORMAT, data)
self.leap_indicator = unpacked_data[0] >> 6 # 2 bits
self.version_number = unpacked_data[0] >> 3 & 0b111 # 3 bits
self.mode = unpacked_data[0] & 0b111 # 3 bits
self.stratum = unpacked_data[1] # 1 byte
self.pool = unpacked_data[2] # 1 byte
self.precision = unpacked_data[3] # 1 byte
# 2 bytes | 2 bytes
self.root_delay = (unpacked_data[4] >> 16) +
(unpacked_data[4] & 0xFFFF) / 2 ** 16
# 2 bytes | 2 bytes
self.root_dispersion = (unpacked_data[5] >> 16) +
(unpacked_data[5] & 0xFFFF) / 2 ** 16
# 4 bytes
self.ref_id = str((unpacked_data[6] >> 24) & 0xFF) + " " +
str((unpacked_data[6] >> 16) & 0xFF) + " " +
str((unpacked_data[6] >> 8) & 0xFF) + " " +
str(unpacked_data[6] & 0xFF)
self.reference = unpacked_data[7] + unpacked_data[8] / 2 ** 32 # 8 bytes
self.originate = unpacked_data[9] + unpacked_data[10] / 2 ** 32 # 8 bytes
self.receive = unpacked_data[11] + unpacked_data[12] / 2 ** 32 # 8 bytes
self.transmit = unpacked_data[13] + unpacked_data[14] / 2 ** 32 # 8 bytes
return self
No ka poʻe palaualelo, ma ke ʻano he noi - code e hoʻohuli i ka pūʻolo i kahi kaula nani
def to_display(self):
return "Leap indicator: {0.leap_indicator}n"
"Version number: {0.version_number}n"
"Mode: {0.mode}n"
"Stratum: {0.stratum}n"
"Pool: {0.pool}n"
"Precision: {0.precision}n"
"Root delay: {0.root_delay}n"
"Root dispersion: {0.root_dispersion}n"
"Ref id: {0.ref_id}n"
"Reference: {0.reference}n"
"Originate: {0.originate}n"
"Receive: {0.receive}n"
"Transmit: {0.transmit}"
.format(self)
Ka hoʻouna ʻana i kahi pūʻolo i ke kikowaena
E hoʻouna i kahi ʻeke me nā kahua piha i ke kikowaena Version, ano и ke hoʻouna i. ka ke hoʻouna i Pono ʻoe e kuhikuhi i ka manawa o kēia manawa ma ka mīkini kūloko (ka helu o kekona mai Ianuali 1, 1900), mana - kekahi o 1-4, mode - 3 (cond client).
Ua loaʻa i ke kikowaena ka noi, hoʻopiha i nā kahua āpau i ka ʻeke NTP, ke kope ʻana i ke kahua Hoʻomaka waiwai mai ke hoʻouna i, i hele mai i loko o ke noi. He mea pohihihi ia iaʻu no ke aha e hiki ʻole ai i ka mea kūʻai ke hoʻopiha koke i ka waiwai o kona manawa ma ke kula Hoʻomaka. ʻO ka hopena, i ka wā e hoʻi mai ai ka ʻeke, loaʻa i ka mea kūʻai aku nā koina manawa 4 - ka manawa i hoʻouna ʻia ai ka noi (Hoʻomaka), ka manawa i loaʻa ai i ke kikowaena ke noi (E loaʻa), ka manawa i hoʻouna ai ke kikowaena i ka pane (ke hoʻouna i) a me ka manawa o ka loaʻa ʻana o ka pane a ka mea kūʻai aku - E holo (ʻaʻole i loko o ka pūʻolo). Me kēia mau waiwai hiki iā mākou ke hoʻonohonoho i ka manawa kūpono.
Ka hoʻouna ʻana a me ka loaʻa ʻana o ke code
# Time difference between 1970 and 1900, seconds
FORMAT_DIFF = (datetime.date(1970, 1, 1) - datetime.date(1900, 1, 1)).days * 24 * 3600
# Waiting time for recv (seconds)
WAITING_TIME = 5
server = "pool.ntp.org"
port = 123
packet = NTPPacket(version_number=2, mode=3, transmit=time.time() + FORMAT_DIFF)
answer = NTPPacket()
with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
s.settimeout(WAITING_TIME)
s.sendto(packet.pack(), (server, port))
data = s.recv(48)
arrive_time = time.time() + FORMAT_DIFF
answer.unpack(data)
ʻIkepili ʻikepili mai ke kikowaena
ʻO ka hana ʻana o ka ʻikepili mai ke kikowaena ua like ia me nā hana a ke keonimana Pelekane mai ka pilikia kahiko o Raymond M. Smallian (1978): "ʻAʻole i loaʻa i kahi kanaka kahi wati, akā aia kahi uaki pā pololei ma ka home, ʻo ia kāna. poina i kekahi manawa i ka makani. I kekahi lā, poina ʻo ia i ka hoʻomaka hou ʻana i ka uaki, hele ʻo ia e kipa i kona hoa, hoʻomoe me ia i ke ahiahi, a i kona hoʻi ʻana i ka hale, ua hoʻonohonoho pono ʻo ia i ka uaki. Pehea ʻo ia e hana ai inā ʻaʻole i ʻike mua ʻia ka manawa huakaʻi? ʻO ka pane: “I ka haʻalele ʻana i ka hale, hoʻomaka ke kanaka i ka uaki a hoʻomanaʻo i ke kūlana o nā lima. Ke hele mai nei i kahi hoaaloha a haʻalele i nā malihini, ʻike ʻo ia i ka manawa o kona hiki ʻana a haʻalele. Hiki iā ia ke ʻike i ka lōʻihi o kona hele ʻana. Ke hoʻi nei i ka home a nānā i ka uaki, hoʻoholo ke kanaka i ka lōʻihi o kona haʻalele ʻana. I ka unuhi ʻana mai kēia manawa i ka manawa āna i kipa ai, ʻike ke kanaka i ka manawa i hala ma ke alanui ma laila a hoʻi. Ma ka hoʻohui ʻana i ka hapalua o ka manawa ma ke alanui i ka manawa o ka haʻalele ʻana i nā malihini, loaʻa iā ia ka manawa e ʻike ai i ka manawa o ka hōʻea ʻana i ka home a hoʻoponopono i nā lima o kāna uaki e like me ia.
E huli i ka manawa e hana ana ke kikowaena ma ka noi:
- Ke ʻimi nei i ka manawa huakaʻi packet mai ka mea kūʻai aku i ke kikowaena: ((Hele mai - Kumu) - (Hoʻouna - Loaʻa)) / 2
- E ʻike i ka ʻokoʻa ma waena o ka mea kūʻai aku a me ka manawa kikowaena:
Loaʻa - Hoʻomaka - ((Hele - Hoʻomaka) - (Hoʻouna - Loaʻa)) / 2 =
2 * Loaʻa - 2 * Hoʻomaka - Hōʻea + Hoʻomaka + Hoʻouna - Loaʻa =
Loaʻa - Hoʻomaka - Hōʻea + Hoʻouna
Hoʻohui mākou i ka waiwai i loaʻa i ka manawa kūloko a hauʻoli i ke ola.
Hua Hua
time_different = answer.get_time_different(arrive_time)
result = "Time difference: {}nServer time: {}n{}".format(
time_different,
datetime.datetime.fromtimestamp(time.time() + time_different).strftime("%c"),
answer.to_display())
print(result)
Pono .
Source: www.habr.com