Talofa, Habrausers. O le asō ou te fia talanoa e uiga i le auala e tusi ai lau lava NTP client faigofie. O le mea moni, o le talanoaga o le a liliu atu i le fausaga o le afifi ma le auala e faʻatautaia ai le tali mai le NTP server. O le code o le a tusia i le Python, aua e foliga mai ia te aʻu e leai se gagana sili atu mo ia mea. Connoisseurs o le a matauina le tutusa o le code ma le ntplib code - na "musuia" aʻu.
O le a tonu la le NTP? O le NTP o se faʻasalalauga mo fegalegaleaiga ma saʻo taimi saʻo. O lo'o fa'aogaina lenei fa'atonuga i le tele o masini fa'aonaponei. Mo se faʻataʻitaʻiga, o le w32tm service in windows.
E 5 fa'asologa o le NTP protocol i le aofa'i. Muamua, version 0 (1985, RFC958)), ua manatu nei ua le toe aoga. O lea la ua fa'aogaina mea fou, 1st (1988, RFC1059), 2nd (1989, RFC1119), 3rd (1992, RFC1305) ma le 4th (1996, RFC2030). Fa'aliliuga 1-4 e fetaui ma le tasi ma le isi; e ese'ese na'o le fa'agaioia o fa'agaioiga a le server.
Fa'asologa o afifi
Faailoga oso (fa'ailoga fa'asa'oga) - o se numera e fa'aalia ai se lapataiga e uiga i le fa'amaopoopo lona lua. Uiga:
- 0 – leai se faasa’oga
- 1 – o le minute mulimuli o le aso e iai le 61 sekone
- 2 – o le minute mulimuli o le aso e iai le 59 sekone
- 3 - faʻaletonu le server (e le o faʻatasi le taimi)
Numera numera (numera fa'aliliuga) – NTP protocol version number (1-4).
āʻega (mode) - faiga fa'agaioiga a le tagata e auina atu pepa. Tau mai le 0 i le 7, sili ona taatele:
- 3 – tagata o tausia
- 4 – server
- 5 – ala fa'asalalau
stratum (tulaga faʻapipiʻi) - o le numera o le vaeluagalemu i le va o le 'auʻaunaga ma le uati faʻasino (1 - e ave saʻo e le 'auʻaunaga faʻamaumauga mai le uati faʻasino, 2 - e ave e le 'auʻaunaga faʻamaumauga mai se 'auʻaunaga ma le layer 1, ma isi).
vaitāʻele ose numera saini e fai ma sui o le va maualuga i le va o fe'au soso'o. O le NTP client o lo'o fa'amaoti mai iinei le va'aiga lea e fa'amoemoe e su'esu'e ai le 'au'aunaga, ae fa'amaoti mai e le NTP server le va'aiga e fa'amoemoe e su'eina ai. O le tau e tutusa ma le binary logarithm o sekone.
matuā saʻo (saʻo) o se numera saini e fai ma sui o le saʻo o le uati faiga. O le tau e tutusa ma le binary logarithm o sekone.
Fa'atuai a'a (fa'atuai o le server) - o le taimi e alu ai le faitau o le uati e o'o atu i le NTP server, o se numera fa'amautu o sekone.
Ta'ape a'a (server spread) - fa'asalalauina o faitauga o le uati a le server NTP e pei o se numera o sekone ma se fa'amaumau.
Ref id (puna fa'ailoa) - uati id. Afai o le server e iai le stratum 1, o le ref id o le igoa o le uati atomic (4 ASCII mataitusi). Afai e fa'aogaina e le 'au'aunaga se isi 'au'aunaga, ona iai lea i le ref id le tuatusi o lenei 'au'aunaga.
O fanua mulimuli e 4 o loʻo faʻatusalia ai le taimi - 32 bits - o le vaega numera, 32 bits - o le vaega vaevaega.
Tusitaiala - o faitauga lata mai uati i luga o le server.
Amataga – taimi na lafo atu ai le pepa (faatumu e le server - sili atu i lalo ifo).
Talia – taimi na maua ai e le server le afifi.
faʻasalalau – taimi e lafo ai le pepa mai le server i le kalani (faatumu e le kalani, sili atu i lalo ifo).
O le a tatou le iloiloina vaega mulimuli e lua.
Tatou tusi la tatou afifi:
Fa'ailoga o le afifi
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
Ina ia lafo (ma maua) se afifi i le 'au'aunaga, e tatau ona mafai ona tatou fa'aliliuina i se laina byte.
Mo lenei (ma fesuiaʻi) gaioiga, o le a matou tusia ni galuega se lua - pack() ma le unpack():
galuega fa'apipi'i
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))
tatala galuega
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
Mo tagata paie, o se talosaga - code lea e liliu ai se afifi i se manoa matagofie
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)
Tuuina atu o se afifi i le server
E tatau ona lafo i le 'au'aunaga se pepa o lo'o fa'atumu uma fanua faʻamatalaga, āʻega и faʻasalalau. le faʻasalalau e tatau ona e faʻamaonia le taimi nei i luga o le masini i le lotoifale (le numera o sekone talu mai Ianuari 1, 1900), faʻamatalaga - soʻo se 1-4, mode - 3 (tagata faʻatau).
O le server, i le taliaina o le talosaga, faʻatumu uma fanua i totonu o le NTP packet, kopi i totonu o le fanua Amataga taua mai faʻasalalau, lea na sau i le talosaga. Ose mea lilo ia te a'u pe aisea e le mafai ai e le kalani ona vave faatumu le taua o lona taimi i le fanua Amataga. O le iʻuga, pe a toe foʻi mai le afifi, e 4 taimi faʻatauga a le kalani - o le taimi na lafoina ai le talosaga (Amataga), taimi na maua ai e le server le talosaga (Talia), taimi na auina atu ai e le server le tali (faʻasalalau) ma le taimi na maua ai e le kalani le tali - Taunuu (e le oi totonu o le afifi). O le faʻaaogaina o nei tau e mafai ona tatou setiina le taimi saʻo.
Fa'ailoga o le lafo ma le mauaina o pusa
# 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)
Fa'atonuina fa'amaumauga mai le 'au'aunaga
O le fa'agaioia o fa'amaumauga mai le 'au'aunaga e talitutusa lava ma gaioiga a le ali'i Peretania mai le fa'afitauli tuai a Raymond M. Smullyan (1978): “O se tasi tagata e leai sana uati tapulima, ae sa i ai se uati puipui sa'o i le fale, lea na galo i nisi taimi. e matagi. I se tasi aso, ua galo ai ona toe viliina lana uati, na alu ai e asi lana uo, ma faaalu le afiafi faatasi ma ia, ma ina ua toe foi i le fale, sa mafai ona ia setiina le uati saʻo. Na faapefea ona ia faia lenei mea pe afai e leʻi iloa muamua le taimi o le malaga? O le tali: “Pe a alu ese mai le fale, e vili e se tagata lana uati ma manatua le tulaga o loo i ai lima. Ina ua sau i se uo ma tuua le au valaaulia, na ia matauina le taimi o lona taunuu mai ma le alu ese. O lenei mea e mafai ai e ia ona iloa le umi na ia asiasi ai. Toe foi i le fale ma tilotilo i le uati, e fuafua e se tagata le umi o lona toesea. E ala i le toesea mai lea taimi o le taimi na ia faaaluina e asiasi atu ai, e iloa ai e se tagata le taimi na alu ai e malaga ai iina ma toe foi mai. E ala i le faaopoopo atu o le afa o le taimi i luga o le auala i le taimi e tuua ai mālō, na te maua ai le avanoa e iloa ai le taimi e taunuu ai i le fale ma fetuutuunai lima o lana uati e tusa ai.”
Su'e le taimi o lo'o galue ai le server ile talosaga:
- Su'e le taimi femalagaa'i o le afifi mai le kalani i le server: ((Taunuu – Afua mai) – (Faasalalau – Maua)) / 2
- Su'e le eseesega i le va o le tagata o tausia ma le taimi o le server:
Maua - Maua - ((Tauu - Afua) - (Auina - Maua)) / 2 =
2 * Maua – 2 * Amata – Taunuu + Amata + Tuuina atu – Maua =
Maua – Amata – Taunuu + Faasalalau
Tatou te faaopoopo le tau aogā i le taimi o le atunuu ma olioli ai i le olaga.
Tulaga o le taunuuga
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)
E aoga .
puna: www.habr.com