README
E
NtpError
- ::begin_pollClockFilter::begin_poll
- ::estimateClockFilter::estimate
- ::newClockFilter::new
- ::observeClockFilter::observe
T
Consensus
- ::encodeDatagram::encode
T
ExtensionField
- ::root_distanceFilterEstimate::root_distance
T
FilterSample
- ::encodePacket::encode
- ::kiss_codePacket::kiss_code
- ::reference_stringPacket::reference_string
- ::root_distancePacket::root_distance
- ::validate_healthPacket::validate_health
T
PeerEstimate
T
ResponseInfo
T
Sample
- ::differenceTimestamp::difference
- ::near_unixTimestamp::near_unix
- ::unix_secondsTimestamp::unix_seconds
- ::zeroTimestamp::zero
V
analyze
V
combine_peers
V
decode
V
decode_datagram
V
from_unix
V
lowest_delay
V
measure
V
request

ntp

NTP packet analysis, authenticated UDP, clock filters and source consensus

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Author

xuting22

Version

0.4.0

License

MIT

Repository

github.com/xuting22/moonbit-ntp

Last updated

4 hours ago

Downloads

#可执行 API 示例

MoonBit API 示例随两个后端测试运行。Node UDP、认证和浏览器宿主另有集成检查。

///|
test "empty measurement selection" {
  assert_true(@ntp.lowest_delay([]) is None)
}

///|
test "eight-stage clock filter example" {
  let filter = @ntp.ClockFilter::new()
  for i = 1; i <= 8; i = i + 1 {
    let now = i.to_double()
    filter.begin_poll(now)
    ignore(
      filter.observe({
        offset_seconds: 0.01,
        delay_seconds: 0.02,
        dispersion_seconds: 0.000001,
        received_at: now,
      }),
    )
  }
  let result = filter.estimate(8.0).unwrap()
  assert_eq(result.valid_samples, 8)
  assert_eq(result.reach, 255)
  assert_eq(result.offset_seconds, 0.01)
  assert_true(!result.fresh)
}

过滤器返回统计估计；fresh=false 表示最佳样本没有更新。这里不修改操作系统时钟，也不实现完整 NTP daemon。

NtpError

source

pub suberror NtpError {
  Invalid(String)
} derive(@moonbitlang/core/debug.Debug
Debug)

ClockFilter

source

pub struct ClockFilter {
  entries : Array[FilterSample]
  precision : Double
  tolerance : Double
  last_time : Double?
  accepted : FilterEstimate?
  reach : Int
} derive(@moonbitlang/core/debug.Debug
Debug)

ClockFilter::begin_poll

source

fn ClockFilter::begin_poll(self : ClockFilter, now : Double) -> Unit raise NtpError

Call once when beginning a poll. After three missed polls a dummy is shifted into the filter, so eight subsequent missing polls eventually replace it.

ClockFilter::estimate

source

fn ClockFilter::estimate(self : ClockFilter, now : Double) -> FilterEstimate? raise NtpError

Snapshot statistics age without mutating stage arrival times. The fresh flag indicates whether this lowest-delay sample has advanced the accepted epoch.

ClockFilter::new

source

fn ClockFilter::new(precision_seconds? : Double, frequency_tolerance? : Double) -> ClockFilter raise NtpError

Eight stages, MAXDISP 16 seconds, PHI 15 ppm; no OS clock discipline.

ClockFilter::observe

source

fn ClockFilter::observe(self : ClockFilter, sample : FilterSample) -> FilterEstimate? raise NtpError

Consensus

source

pub(all) struct Consensus {
  offset_seconds : Double
  jitter_seconds : Double
  selection_jitter_seconds : Double
  interval_low : Double
  interval_high : Double
  system_peer : String
  survivors : Array[String]
  rejected : Array[String]
} derive(@moonbitlang/core/debug.Debug
Debug)

Datagram

source

pub(all) struct Datagram {
  header : Packet
  extensions : Array[ExtensionField]
  mac : Bytes
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Datagram::encode

source

fn Datagram::encode(self : Datagram) -> Bytes raise NtpError

ExtensionField

source

pub(all) struct ExtensionField {
  field_type : Int
  value : Bytes
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

FilterEstimate

source

pub(all) struct FilterEstimate {
  offset_seconds : Double
  delay_seconds : Double
  dispersion_seconds : Double
  jitter_seconds : Double
  selected_at : Double
  evaluated_at : Double
  valid_samples : Int
  reach : Int
  fresh : Bool
} derive(@moonbitlang/core/debug.Debug
Debug)

FilterEstimate::root_distance

source

fn FilterEstimate::root_distance(self : FilterEstimate, root_delay_seconds : Double, root_dispersion_seconds : Double) -> Double raise NtpError

FilterSample

source

pub(all) struct FilterSample {
  offset_seconds : Double
  delay_seconds : Double
  dispersion_seconds : Double
  received_at : Double
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Packet

source

pub(all) struct Packet {
  leap : Int
  version : Int
  mode : Int
  stratum : Int
  poll : Int
  precision : Int
  root_delay : Int
  root_dispersion : UInt
  reference_id : UInt
  reference : Timestamp
  origin : Timestamp
  receive : Timestamp
  transmit : Timestamp
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Packet::encode

source

fn Packet::encode(self : Packet) -> Bytes raise NtpError

Packet::kiss_code

source

fn Packet::kiss_code(self : Packet) -> String?

Returns an ASCII kiss-of-death code for stratum-zero replies.

Packet::reference_string

source

fn Packet::reference_string(self : Packet) -> String

Packet::root_distance

source

fn Packet::root_distance(self : Packet, sample : Sample) -> Double

Single-sample root distance; excludes multi-sample jitter and clock filtering.

Packet::validate_health

source

fn Packet::validate_health(self : Packet) -> Unit raise NtpError

Check synchronization health in addition to measure's request/time validation. Freshness and peer-distance limits follow beevik/ntp's Validate defaults.

PeerEstimate

source

pub(all) struct PeerEstimate {
  id : String
  offset_seconds : Double
  root_distance_seconds : Double
  jitter_seconds : Double
  stratum : Int
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

ResponseInfo

source

pub(all) struct ResponseInfo {
  sample : Sample
  minimum_error_seconds : Double
  server_transmit_unix : Double
  reference_unix : Double
  precision_seconds : Double
  poll_seconds : Double
  root_distance_seconds : Double
  reference_string : String
} derive(@moonbitlang/core/debug.Debug
Debug)

Sample

source

pub struct Sample {
  offset_seconds : Double
  delay_seconds : Double
} derive(@moonbitlang/core/debug.Debug
Debug)

Timestamp

source

pub(all) struct Timestamp {
  seconds : UInt
  fraction : UInt
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Timestamp::difference

source

fn Timestamp::difference(self : Timestamp, earlier : Timestamp) -> Double

Modular signed seconds handle era rollover; intervals must be less than 2^31 seconds.

Timestamp::near_unix

source

fn Timestamp::near_unix(self : Timestamp, pivot : Double) -> Double raise NtpError

Resolve within half an NTP era of a trusted local pivot (pivot in eras 0/1).

Timestamp::unix_seconds

source

fn Timestamp::unix_seconds(self : Timestamp, era : Int) -> Double raise NtpError

NTP era is supplied by the caller: 0 before 2036 rollover, 1 afterwards.

Timestamp::zero

source

fn Timestamp::zero() -> Timestamp

analyze

source

fn analyze(sent : Timestamp, reply : Packet, arrived : Timestamp, pivot_unix : Double) -> ResponseInfo raise NtpError

Rich SNTP analysis. A small negative measured network delay is clamped to zero, as in beevik/ntp; strict measure() retains its existing rejection.

combine_peers

source

fn combine_peers(peers : Array[PeerEstimate], minimum? : Int, cluster_minimum? : Int, maximum_distance? : Double) -> Consensus? raise NtpError

RFC 5905 section 11.2 interval selection, iterative clustering and inverse-root-distance combination. This does not perform clock discipline.

decode

source

fn decode(bytes : Bytes) -> Packet raise NtpError

decode_datagram

source

fn decode_datagram(bytes : Bytes, mac_length? : Int) -> Datagram raise NtpError

Explicit expected MAC size avoids guessing whether a tail is an extension. Supports no MAC, a 4-byte crypto-NAK, or the common 20/24-byte MAC forms.

from_unix

source

fn from_unix(seconds : Double) -> (Timestamp, Int) raise NtpError

lowest_delay

source

fn lowest_delay(samples : Array[Sample]) -> Sample?

Choose the valid measurement with minimum observed network delay. This is a single-stage selector, not the complete RFC clock-filter algorithm.

measure

source

fn measure(sent : Timestamp, reply : Packet, arrived : Timestamp) -> Sample raise NtpError

Verifies basic server reply and computes RFC four-timestamp estimates. Caller supplies the original request timestamp and local receipt timestamp.

request

source

fn request(transmit : Timestamp) -> Packet

Source Files

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ntp

#可执行 API 示例

#NtpError

#ClockFilter

#ClockFilter::begin_poll

#ClockFilter::estimate

#ClockFilter::new

#ClockFilter::observe

#Consensus

#Datagram

#Datagram::encode

#ExtensionField

#FilterEstimate

#FilterEstimate::root_distance

#FilterSample

#Packet

#Packet::encode

#Packet::kiss_code

#Packet::reference_string

#Packet::root_distance

#Packet::validate_health

#PeerEstimate

#ResponseInfo

#Sample

#Timestamp

#Timestamp::difference

#Timestamp::near_unix

#Timestamp::unix_seconds

#Timestamp::zero

#analyze

#combine_peers

#decode

#decode_datagram

#from_unix

#lowest_delay

#measure

#request

Source Files

NtpError

ClockFilter

ClockFilter::begin_poll

ClockFilter::estimate

ClockFilter::new

ClockFilter::observe

Consensus

Datagram

Datagram::encode

ExtensionField

FilterEstimate

FilterEstimate::root_distance

FilterSample

Packet

Packet::encode

Packet::kiss_code

Packet::reference_string

Packet::root_distance

Packet::validate_health

PeerEstimate

ResponseInfo

Sample

Timestamp

Timestamp::difference

Timestamp::near_unix

Timestamp::unix_seconds

Timestamp::zero

analyze

combine_peers

decode

decode_datagram

from_unix

lowest_delay

measure

request