├── .github ├── dependabot.yml └── workflows │ ├── codeql-analysis.yml │ ├── nodejs.yml │ ├── npm-release.md │ ├── npm-release.yml │ └── prettier.yml ├── .gitignore ├── LICENSE ├── README.md ├── examples └── example.js ├── package.json ├── src ├── NtpTimeResult.ts ├── NtpTimeSync.ts ├── RecursivePartial.ts └── index.ts ├── tsconfig.json └── yarn.lock /.github/dependabot.yml: -------------------------------------------------------------------------------- 1 | version: 2 2 | updates: 3 | - package-ecosystem: "npm" 4 | directory: "/" 5 | schedule: 6 | interval: "weekly" 7 | -------------------------------------------------------------------------------- /.github/workflows/codeql-analysis.yml: -------------------------------------------------------------------------------- 1 | # For most projects, this workflow file will not need changing; you simply need 2 | # to commit it to your repository. 3 | # 4 | # You may wish to alter this file to override the set of languages analyzed, 5 | # or to provide custom queries or build logic. 6 | # 7 | # ******** NOTE ******** 8 | # We have attempted to detect the languages in your repository. Please check 9 | # the `language` matrix defined below to confirm you have the correct set of 10 | # supported CodeQL languages. 11 | # 12 | name: "CodeQL" 13 | 14 | on: 15 | push: 16 | branches: [ master ] 17 | pull_request: 18 | # The branches below must be a subset of the branches above 19 | branches: [ master ] 20 | schedule: 21 | - cron: '30 10 * * 2' 22 | 23 | jobs: 24 | analyze: 25 | name: Analyze 26 | runs-on: ubuntu-latest 27 | permissions: 28 | actions: read 29 | contents: read 30 | security-events: write 31 | 32 | strategy: 33 | fail-fast: false 34 | matrix: 35 | language: [ 'javascript' ] 36 | # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python' ] 37 | # Learn more: 38 | # https://docs.github.com/en/free-pro-team@latest/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#changing-the-languages-that-are-analyzed 39 | 40 | steps: 41 | - name: Checkout repository 42 | uses: actions/checkout@v4 43 | 44 | # Initializes the CodeQL tools for scanning. 45 | - name: Initialize CodeQL 46 | uses: github/codeql-action/init@v3 47 | with: 48 | languages: ${{ matrix.language }} 49 | # If you wish to specify custom queries, you can do so here or in a config file. 50 | # By default, queries listed here will override any specified in a config file. 51 | # Prefix the list here with "+" to use these queries and those in the config file. 52 | # queries: ./path/to/local/query, your-org/your-repo/queries@main 53 | 54 | # Autobuild attempts to build any compiled languages (C/C++, C#, or Java). 55 | # If this step fails, then you should remove it and run the build manually (see below) 56 | - name: Autobuild 57 | uses: github/codeql-action/autobuild@v3 58 | 59 | # ℹ️ Command-line programs to run using the OS shell. 60 | # 📚 https://git.io/JvXDl 61 | 62 | # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines 63 | # and modify them (or add more) to build your code if your project 64 | # uses a compiled language 65 | 66 | #- run: | 67 | # make bootstrap 68 | # make release 69 | 70 | - name: Perform CodeQL Analysis 71 | uses: github/codeql-action/analyze@v3 72 | -------------------------------------------------------------------------------- /.github/workflows/nodejs.yml: -------------------------------------------------------------------------------- 1 | name: Node.js build 2 | 3 | on: 4 | push: 5 | branches: [ master ] 6 | pull_request: 7 | branches: [ master ] 8 | 9 | jobs: 10 | build: 11 | runs-on: ubuntu-latest 12 | strategy: 13 | matrix: 14 | node-version: ['18', '20', '22'] 15 | steps: 16 | - uses: actions/checkout@v4 17 | - name: Use Node.js ${{ matrix.node-version }} 18 | uses: actions/setup-node@v4 19 | with: 20 | node-version: ${{ matrix.node-version }} 21 | check-latest: true 22 | - name: Cache Node.js modules 23 | id: yarn-cache 24 | uses: actions/cache@v4 25 | with: 26 | path: '**/node_modules' 27 | key: ${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}-${{ matrix.node-version }} 28 | - name: Install dependencies 29 | if: steps.yarn-cache.outputs.cache-hit != 'true' 30 | run: yarn install 31 | - name: Build 32 | run: yarn build 33 | - name: Run examples 34 | run: node examples/example.js 35 | -------------------------------------------------------------------------------- /.github/workflows/npm-release.md: -------------------------------------------------------------------------------- 1 | # NPM release 2 | 3 | 1. Bump version: 4 | ```bash 5 | yarn version --patch 6 | ``` 7 | 8 | 2. Push changes and tags: 9 | ```bash 10 | git push --follow-tags 11 | ``` 12 | 13 | 3. [Wait for tag pipeline to become green](https://github.com/buffcode/ntp-time-sync/actions) 14 | 15 | 4. [Create a new release on GitHub](https://github.com/buffcode/ntp-time-sync/releases/new) 16 | - Choose the tag from step 1/2 17 | - Title is `v{version}` 18 | - Give some description on what changed 19 | -------------------------------------------------------------------------------- /.github/workflows/npm-release.yml: -------------------------------------------------------------------------------- 1 | name: Node.js Package 2 | 3 | on: 4 | workflow_dispatch: 5 | release: 6 | types: [released] 7 | 8 | jobs: 9 | publish: 10 | runs-on: ubuntu-latest 11 | steps: 12 | - uses: actions/checkout@v2 13 | - uses: actions/setup-node@v2 14 | with: 15 | node-version: '20' 16 | registry-url: 'https://registry.npmjs.org' 17 | - run: yarn install 18 | - run: yarn build 19 | - run: npm publish 20 | env: 21 | NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }} 22 | -------------------------------------------------------------------------------- /.github/workflows/prettier.yml: -------------------------------------------------------------------------------- 1 | name: Codestyle 2 | 3 | on: 4 | push: 5 | branches: [ master ] 6 | pull_request: 7 | branches: [ master ] 8 | 9 | jobs: 10 | build: 11 | runs-on: ubuntu-latest 12 | strategy: 13 | matrix: 14 | node-version: ['22'] 15 | steps: 16 | - uses: actions/checkout@v4 17 | - name: Use Node.js ${{ matrix.node-version }} 18 | uses: actions/setup-node@v4 19 | with: 20 | node-version: ${{ matrix.node-version }} 21 | check-latest: true 22 | - name: Cache Node.js modules 23 | id: yarn-cache 24 | uses: actions/cache@v4 25 | with: 26 | path: '**/node_modules' 27 | key: ${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}-${{ matrix.node-version }} 28 | - name: Install dependencies 29 | if: steps.yarn-cache.outputs.cache-hit != 'true' 30 | run: yarn install 31 | - name: Check code style 32 | run: yarn prettier:lint 33 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Logs 2 | logs 3 | *.log 4 | npm-debug.log* 5 | yarn-debug.log* 6 | yarn-error.log* 7 | 8 | # Runtime data 9 | pids 10 | *.pid 11 | *.seed 12 | *.pid.lock 13 | 14 | # Directory for instrumented libs generated by jscoverage/JSCover 15 | lib-cov 16 | 17 | # Coverage directory used by tools like istanbul 18 | coverage 19 | 20 | # nyc test coverage 21 | .nyc_output 22 | 23 | # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files) 24 | .grunt 25 | 26 | # Bower dependency directory (https://bower.io/) 27 | bower_components 28 | 29 | # node-waf configuration 30 | .lock-wscript 31 | 32 | # Compiled binary addons (http://nodejs.org/api/addons.html) 33 | build/Release 34 | 35 | # Dependency directories 36 | node_modules/ 37 | jspm_packages/ 38 | 39 | # Typescript v1 declaration files 40 | typings/ 41 | 42 | # Optional npm cache directory 43 | .npm 44 | 45 | # Optional eslint cache 46 | .eslintcache 47 | 48 | # Optional REPL history 49 | .node_repl_history 50 | 51 | # Output of 'npm pack' 52 | *.tgz 53 | 54 | # Yarn Integrity file 55 | .yarn-integrity 56 | 57 | # dotenv environment variables file 58 | .env 59 | 60 | /dist/ 61 | /.idea/ 62 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | ![NPM downloads](https://img.shields.io/npm/dt/ntp-time-sync.svg) 2 | [![Build Status](https://github.com/buffcode/ntp-time-sync/actions/workflows/nodejs.yml/badge.svg)](https://github.com/buffcode/ntp-time-sync/actions) 3 | ![NPM version](https://img.shields.io/npm/v/ntp-time-sync) 4 | 5 | # ntp-time-sync 6 | Node.JS module to fetch the current time from NTP servers and returns offset information. 7 | 8 | **:information_source: NTP requires UDP which is not available in a browser context!** 9 | 10 | ## Installation 11 | ```bash 12 | # using Yarn 13 | $ yarn add ntp-time-sync 14 | 15 | # using NPM 16 | $ npm install ntp-time-sync 17 | ``` 18 | 19 | ## Usage 20 | Consider using the library as a singleton, so that not every call to `getTime` fires new NTP packages. 21 | The library itself will manage minimum/maximum poll times. 22 | 23 | Several requests to multiple NTP time servers are fired and the responses will be aggregated. 24 | 25 | ```js 26 | // ES6: 27 | import { NtpTimeSync } from "ntp-time-sync"; 28 | // pre-ES6: 29 | // const NtpTimeSync = require("ntp-time-sync").NtpTimeSync; 30 | 31 | const timeSync = NtpTimeSync.getInstance(); 32 | 33 | // request 1 34 | timeSync.getTime().then(function (result) { 35 | console.log("current system time", new Date()); 36 | console.log("real time", result.now); 37 | console.log("offset in milliseconds", result.offset); 38 | }) 39 | 40 | // request 2, will use cached offset from previous request 41 | timeSync.getTime().then(function (result) { 42 | console.log("current system time", new Date()); 43 | console.log("real time", result.now); 44 | console.log("offset in milliseconds", result.offset); 45 | }) 46 | 47 | // ES2017 style 48 | const result = await timeSync.getTime(); 49 | console.log("real time", result.now); 50 | ``` 51 | 52 | `.getTime()` returns a `Promise` object which will eventually be resolved with a object containing the following information: 53 | 54 | | Property | Description | 55 | | :--- | :--- | 56 | | `now` | Current NTP time ("real time") | 57 | | `offset` | Calculated offset between local system time and NTP time | 58 | 59 | `.now()` returns a `Date` object containing the correct time for the moment when the function was called. 60 | In contrast to `getTime()`, which will return the correct time for the moment the Promise gets resolved. 61 | 62 | ## Options 63 | You can pass custom options to the constructor of `NtpTimeSync` or `NtpTimeSync.getInstance(options)`. 64 | These will be merged with the following defaults: 65 | 66 | ```js 67 | const defaultOptions = { 68 | // list of NTP time servers, optionally including a port (defaults to 123) 69 | servers: [ 70 | "0.pool.ntp.org", 71 | "1.pool.ntp.org", 72 | "2.pool.ntp.org", 73 | "3.pool.ntp.org" 74 | ], 75 | 76 | // required amount of valid samples in order to calculate the time 77 | sampleCount: 8, 78 | 79 | // amount of time in milliseconds to wait for a single NTP response 80 | replyTimeout: 3000, 81 | 82 | // defaults as of RFC5905 83 | ntpDefaults: { 84 | port: 123, 85 | version: 4, 86 | tolerance: 15e-6, 87 | minPoll: 4, 88 | maxPoll: 17, 89 | maxDispersion: 16, 90 | minDispersion: 0.005, 91 | maxDistance: 1, 92 | maxStratum: 16, 93 | precision: -18, 94 | referenceDate: new Date("Jan 01 1900 GMT") 95 | } 96 | }; 97 | ``` 98 | -------------------------------------------------------------------------------- /examples/example.js: -------------------------------------------------------------------------------- 1 | const NtpTimeSync = require("../dist/index").NtpTimeSync; 2 | 3 | (async function() { 4 | const ntpInstance1 = NtpTimeSync.getInstance(); 5 | const ntpInstance2 = NtpTimeSync.getInstance(); 6 | 7 | console.log("is singleton?", ntpInstance1 === ntpInstance2); 8 | 9 | console.log("system time", new Date()); 10 | console.log("ntp time when called", await ntpInstance1.now()); 11 | console.log("ntp time when finished", (await ntpInstance2.getTime()).now); 12 | })(); 13 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "ntp-time-sync", 3 | "version": "0.5.0", 4 | "description": "Fetches the current time from NTP servers and returns offset information", 5 | "main": "dist/index.js", 6 | "dependencies": { 7 | "ntp-packet-parser": "^0.5.0" 8 | }, 9 | "devDependencies": { 10 | "@types/node": "^18 || ^20 || ^22", 11 | "prettier": "3.5.3", 12 | "ts-node": "10.9.2", 13 | "typescript": "5.8.3" 14 | }, 15 | "scripts": { 16 | "prepublishOnly": "yarn prettier:lint && yarn build", 17 | "build": "tsc", 18 | "prettier": "prettier --write src/**/*.ts", 19 | "prettier:lint": "prettier --list-different src/**/*.ts" 20 | }, 21 | "keywords": [ 22 | "ntp", 23 | "clock", 24 | "sync", 25 | "parser", 26 | "udp", 27 | "time" 28 | ], 29 | "author": "Laurens Stötzel", 30 | "repository": { 31 | "type": "git", 32 | "url": "https://github.com/buffcode/ntp-time-sync.git" 33 | }, 34 | "files": [ 35 | "dist", 36 | "src", 37 | "package.json", 38 | "tsconfig.json" 39 | ], 40 | "license": "GPL-3.0", 41 | "prettier": { 42 | "printWidth": 120, 43 | "trailingComma": "es5" 44 | }, 45 | "engines": { 46 | "node": "^18 || ^20 || ^22" 47 | } 48 | } 49 | -------------------------------------------------------------------------------- /src/NtpTimeResult.ts: -------------------------------------------------------------------------------- 1 | export interface NtpTimeResult { 2 | // Correct real time 3 | now: Date; 4 | 5 | // Offset local to real time in milliseconds 6 | offset: number; 7 | 8 | // Precision in milliseconds 9 | precision: number; 10 | } 11 | -------------------------------------------------------------------------------- /src/NtpTimeSync.ts: -------------------------------------------------------------------------------- 1 | "use strict"; 2 | 3 | import * as dgram from "dgram"; 4 | import { NtpPacket, NtpPacketParser } from "ntp-packet-parser"; 5 | import { NtpTimeResult } from "./NtpTimeResult"; 6 | import { RecursivePartial } from "./RecursivePartial"; 7 | 8 | let singleton: NtpTimeSync | undefined; 9 | let lastPoll: number | undefined; 10 | let lastResult: 11 | | undefined 12 | | { 13 | offset: number; 14 | precision: number; 15 | }; 16 | 17 | export interface NtpTimeSyncConstructorOptions { 18 | servers: string[]; 19 | sampleCount: number; 20 | replyTimeout: number; 21 | ntpDefaults: { 22 | port: number; 23 | version: number; 24 | tolerance: number; 25 | minPoll: number; 26 | maxPoll: number; 27 | maxDispersion: number; 28 | minDispersion: number; 29 | maxDistance: number; 30 | maxStratum: number; 31 | precision: number; 32 | referenceDate: Date; 33 | }; 34 | } 35 | 36 | export interface NtpTimeSyncOptions extends Omit { 37 | servers: ReadonlyArray<{ 38 | host: string; 39 | port: number; 40 | }>; 41 | } 42 | 43 | export const NtpTimeSyncDefaultOptions = { 44 | // list of NTP time servers, optionally including a port (defaults to options.ntpDefaults.port = 123) 45 | servers: ["0.pool.ntp.org", "1.pool.ntp.org", "2.pool.ntp.org", "3.pool.ntp.org"], 46 | 47 | // required amount of valid samples 48 | sampleCount: 8, 49 | 50 | // amount of time in milliseconds to wait for an NTP response 51 | replyTimeout: 3000, 52 | 53 | // defaults as of RFC5905 54 | ntpDefaults: { 55 | port: 123, 56 | version: 4, 57 | tolerance: 15e-6, 58 | minPoll: 4, 59 | maxPoll: 17, 60 | maxDispersion: 16, 61 | minDispersion: 0.005, 62 | maxDistance: 1, 63 | maxStratum: 16, 64 | precision: -18, 65 | referenceDate: new Date("Jan 01 1900 GMT"), 66 | }, 67 | }; 68 | 69 | interface NtpReceivedPacket extends Partial { 70 | destinationTimestamp: Date; 71 | } 72 | 73 | interface SampleData { 74 | data: NtpReceivedPacket; 75 | offset: number; 76 | delay: number; 77 | dispersion: number; 78 | } 79 | 80 | export class NtpTimeSync { 81 | private options: NtpTimeSyncOptions; 82 | private samples: SampleData[] = []; 83 | 84 | constructor(options: RecursivePartial = {}) { 85 | const serverConfig = options.servers || NtpTimeSyncDefaultOptions.servers; 86 | 87 | const mergedConfig = this.recursiveResolveOptions( 88 | options, 89 | NtpTimeSyncDefaultOptions 90 | ) as NtpTimeSyncConstructorOptions; 91 | 92 | this.options = { 93 | ...mergedConfig, 94 | servers: serverConfig.map((server) => { 95 | return { 96 | host: server.split(":", 2)[0], 97 | port: Number(server.split(":", 2)[1]) || mergedConfig.ntpDefaults.port, 98 | }; 99 | }), 100 | }; 101 | } 102 | 103 | private recursiveResolveOptions( 104 | options: { [key: string]: any }, 105 | defaults: { [key: string]: any } 106 | ): { [key: string]: any } { 107 | const mergedConfig: [string, any][] = Object.entries(defaults).map(([key, value]) => { 108 | // option was not defined in input 109 | if (!(key in options)) { 110 | return [key, value]; 111 | } 112 | 113 | // option is invalid 114 | if (!(key in defaults)) { 115 | throw new Error(`Invalid option: ${key}`); 116 | } 117 | 118 | if (Array.isArray(options[key])) { 119 | return [key, options[key]]; 120 | } 121 | 122 | if (NtpTimeSync.isPlainObject(options[key])) { 123 | return [key, this.recursiveResolveOptions(options[key], defaults[key])]; 124 | } 125 | 126 | return [key, options[key]]; 127 | }); 128 | 129 | return Object.fromEntries(mergedConfig); 130 | } 131 | 132 | // @see https://quickref.me/check-if-a-value-is-a-plain-object.html 133 | private static isPlainObject(v: any): boolean { 134 | return !!v && typeof v === "object" && (v.__proto__ === null || v.__proto__ === Object.prototype); 135 | } 136 | 137 | /** 138 | * Returns a singleton 139 | */ 140 | static getInstance(options: RecursivePartial = {}): NtpTimeSync { 141 | if (!singleton) { 142 | singleton = new NtpTimeSync(options); 143 | } 144 | 145 | return singleton; 146 | } 147 | 148 | private async collectSamples(numSamples: number) { 149 | let ntpResults: NtpReceivedPacket[] = []; 150 | let retry = 0; 151 | 152 | do { 153 | let timePromises: Promise[] = []; 154 | 155 | this.options.servers.forEach((server) => { 156 | timePromises.push( 157 | this.getNetworkTime(server.host, server.port).then((data) => { 158 | this.acceptResponse(data); 159 | 160 | return data; 161 | }) 162 | ); 163 | }); 164 | 165 | // wait for NTP responses to arrive 166 | ntpResults = ntpResults 167 | .concat(await Promise.all(timePromises.map((p) => p.catch((e) => e)))) 168 | .filter(function (result) { 169 | return !(result instanceof Error); 170 | }); 171 | 172 | if (ntpResults.length === 0) { 173 | retry++; 174 | } 175 | } while (ntpResults.length < numSamples && retry < 3); 176 | 177 | if (ntpResults.length === 0) { 178 | throw new Error("Connection error: Unable to get any NTP response after " + retry + " retries"); 179 | } 180 | 181 | // filter erroneous responses, use valid ones as samples 182 | let samples: SampleData[] = []; 183 | ntpResults.forEach((data) => { 184 | const offsetSign = data.transmitTimestamp.getTime() > data.destinationTimestamp.getTime() ? 1 : -1; 185 | 186 | const offset = 187 | ((Math.abs(data.receiveTimestamp.getTime() - data.originTimestamp.getTime()) + 188 | Math.abs(data.transmitTimestamp.getTime() - data.destinationTimestamp.getTime())) / 189 | 2) * 190 | offsetSign; 191 | 192 | const delay = Math.max( 193 | data.destinationTimestamp.getTime() - 194 | data.originTimestamp.getTime() - 195 | (data.receiveTimestamp.getTime() - data.transmitTimestamp.getTime()), 196 | Math.pow(2, this.options.ntpDefaults.precision) 197 | ); 198 | 199 | const dispersion = 200 | Math.pow(2, data.precision) + 201 | Math.pow(2, this.options.ntpDefaults.precision) + 202 | this.options.ntpDefaults.tolerance * (data.destinationTimestamp.getTime() - data.originTimestamp.getTime()); 203 | 204 | samples.push({ 205 | data: data, 206 | offset: offset, 207 | delay: delay, 208 | dispersion: dispersion, 209 | }); 210 | }); 211 | 212 | // sort samples by ascending delay 213 | samples.sort(function (a, b) { 214 | return a.delay - b.delay; 215 | }); 216 | 217 | // restrict to best n samples 218 | return samples.slice(0, numSamples); 219 | } 220 | 221 | /** 222 | * @param {boolean} force Force NTP update 223 | */ 224 | async getTime(force = false): Promise { 225 | if (!force && lastPoll && Date.now() - lastPoll < Math.pow(2, this.options.ntpDefaults.minPoll) * 1000) { 226 | let date = new Date(); 227 | date.setUTCMilliseconds(date.getUTCMilliseconds() + lastResult.offset); 228 | 229 | return { 230 | now: date, 231 | offset: lastResult.offset, 232 | precision: lastResult.precision, 233 | }; 234 | } 235 | 236 | // update time samples 237 | this.samples = await this.collectSamples(this.options.sampleCount); 238 | 239 | // calculate offset 240 | const offset = 241 | this.samples.reduce((acc, item) => { 242 | return acc + item.offset; 243 | }, 0) / this.samples.length; 244 | 245 | const precision = NtpTimeSync.stdDev(this.samples.map((sample) => sample.offset)); 246 | 247 | lastResult = { 248 | offset: offset, 249 | precision: precision, 250 | }; 251 | lastPoll = Date.now(); 252 | 253 | let date = new Date(); 254 | date.setUTCMilliseconds(date.getUTCMilliseconds() + offset); 255 | 256 | return { 257 | now: date, 258 | offset: offset, 259 | precision: precision, 260 | }; 261 | } 262 | 263 | /** 264 | * Will return the correct timestamp when function was called 265 | */ 266 | async now(force = false) { 267 | const now = new Date(); 268 | const result = await this.getTime(force); 269 | 270 | now.setUTCMilliseconds(now.getUTCMilliseconds() + result.offset); 271 | return now; 272 | } 273 | 274 | private static pad(string: string, length: number, char = "0", side: "left" | "right" = "left") { 275 | if (side === "left") { 276 | return char.repeat(length).substring(0, length - string.length) + string; 277 | } 278 | 279 | return string + char.repeat(length).substring(0, length - string.length); 280 | } 281 | 282 | /** 283 | * @param {Integer} leapIndicator, defaults to 3 (unsynchronized) 284 | * @param {Integer} ntpVersion, defaults to `options.ntpDefaults.version` 285 | * @param {Integer} mode, defaults to 3 (client) 286 | * @return {Buffer} 287 | */ 288 | private createPacket(leapIndicator = 3, ntpVersion: number = null, mode = 3): Buffer { 289 | ntpVersion = ntpVersion || this.options.ntpDefaults.version; 290 | 291 | // generate NTP packet 292 | let ntpData = new Array(48).fill(0); 293 | 294 | ntpData[0] = 295 | // Leap indicator (= 3, unsynchronized) 296 | NtpTimeSync.pad((leapIndicator >>> 0).toString(2), 2) + 297 | // NTP version (= 4) 298 | NtpTimeSync.pad((ntpVersion >>> 0).toString(2), 3) + 299 | // client mode (= 3) 300 | NtpTimeSync.pad((mode >>> 0).toString(2), 3); 301 | 302 | ntpData[0] = parseInt(ntpData[0], 2); 303 | 304 | // origin timestamp 305 | const baseTime = new Date().getTime() - this.options.ntpDefaults.referenceDate.getTime(); 306 | const seconds = baseTime / 1000; 307 | let ntpTimestamp = (seconds * Math.pow(2, 32)).toString(2); 308 | ntpTimestamp = NtpTimeSync.pad(ntpTimestamp, 64); 309 | 310 | // origin timestamp 311 | ntpData[24] = parseInt(ntpTimestamp.substr(0, 8), 2); 312 | ntpData[25] = parseInt(ntpTimestamp.substr(8, 8), 2); 313 | ntpData[26] = parseInt(ntpTimestamp.substr(16, 8), 2); 314 | ntpData[27] = parseInt(ntpTimestamp.substr(24, 8), 2); 315 | ntpData[28] = parseInt(ntpTimestamp.substr(32, 8), 2); 316 | ntpData[29] = parseInt(ntpTimestamp.substr(40, 8), 2); 317 | ntpData[30] = parseInt(ntpTimestamp.substr(48, 8), 2); 318 | ntpData[31] = parseInt(ntpTimestamp.substr(56, 8), 2); 319 | 320 | // transmit timestamp 321 | ntpData[40] = parseInt(ntpTimestamp.substr(0, 8), 2); 322 | ntpData[41] = parseInt(ntpTimestamp.substr(8, 8), 2); 323 | ntpData[42] = parseInt(ntpTimestamp.substr(16, 8), 2); 324 | ntpData[43] = parseInt(ntpTimestamp.substr(24, 8), 2); 325 | ntpData[44] = parseInt(ntpTimestamp.substr(32, 8), 2); 326 | ntpData[45] = parseInt(ntpTimestamp.substr(40, 8), 2); 327 | ntpData[46] = parseInt(ntpTimestamp.substr(48, 8), 2); 328 | ntpData[47] = parseInt(ntpTimestamp.substr(56, 8), 2); 329 | 330 | return Buffer.from(ntpData); 331 | } 332 | 333 | private static cleanup(client: dgram.Socket) { 334 | try { 335 | client.close(); 336 | } catch (e) { 337 | // ignore, as we just want to cleanup 338 | } 339 | } 340 | 341 | getNetworkTime(server: string, port = 123): Promise { 342 | return new Promise((resolve, reject) => { 343 | const client = dgram.createSocket("udp4"); 344 | let hasFinished = false; 345 | 346 | const errorCallback = (err: Error) => { 347 | if (timeoutHandler) { 348 | clearTimeout(timeoutHandler); 349 | timeoutHandler = null; 350 | } 351 | 352 | if (hasFinished) { 353 | return; 354 | } 355 | 356 | NtpTimeSync.cleanup(client); 357 | 358 | hasFinished = true; 359 | reject(err); 360 | }; 361 | 362 | client.on("error", (err) => errorCallback); 363 | 364 | // setup timeout 365 | let timeoutHandler = setTimeout(() => { 366 | errorCallback(new Error("Timeout waiting for NTP response.")); 367 | }, this.options.replyTimeout); 368 | 369 | client.send(this.createPacket(), port, server, (err) => { 370 | if (hasFinished) { 371 | return; 372 | } 373 | 374 | if (err) { 375 | errorCallback(err); 376 | return; 377 | } 378 | 379 | client.once("message", function (msg) { 380 | if (hasFinished) { 381 | return; 382 | } 383 | 384 | clearTimeout(timeoutHandler); 385 | timeoutHandler = null; 386 | client.close(); 387 | 388 | const result: NtpReceivedPacket = { 389 | ...NtpPacketParser.parse(msg), 390 | destinationTimestamp: new Date(), 391 | }; 392 | 393 | hasFinished = true; 394 | resolve(result); 395 | }); 396 | }); 397 | }); 398 | } 399 | 400 | /** 401 | * Test if response is acceptable for synchronization 402 | */ 403 | private acceptResponse(data: Partial) { 404 | /* 405 | * Format error 406 | */ 407 | if (data.version > this.options.ntpDefaults.version) { 408 | throw new Error("Format error: Expected version " + this.options.ntpDefaults.version + ", got " + data.version); 409 | } 410 | 411 | /* 412 | * A stratum error occurs if (1) the server has never been 413 | * synchronized, (2) the server stratum is invalid. 414 | */ 415 | if (data.leapIndicator === 3 || data.stratum >= this.options.ntpDefaults.maxStratum) { 416 | throw new Error("Stratum error: Remote clock is unsynchronized"); 417 | } 418 | 419 | /* 420 | * Verify valid root distance. 421 | */ 422 | const rootDelay = (data.rootDelay.getTime() - this.options.ntpDefaults.referenceDate.getTime()) / 1000; 423 | const rootDispersion = (data.rootDispersion.getTime() - this.options.ntpDefaults.referenceDate.getTime()) / 1000; 424 | if (rootDelay / 2 + rootDispersion >= this.options.ntpDefaults.maxDispersion) { 425 | throw new Error("Distance error: Root distance too large"); 426 | } 427 | 428 | /* 429 | * Verify origin timestamp 430 | */ 431 | if (data.originTimestamp.getTime() > new Date().getTime()) { 432 | throw new Error("Format error: Origin timestamp is from the future"); 433 | } 434 | } 435 | 436 | /** 437 | * Average for a list of numbers 438 | */ 439 | private static avg(values: number[]): number { 440 | const sum = values.reduce(function (sum, value) { 441 | return sum + value; 442 | }, 0); 443 | 444 | return sum / values.length; 445 | } 446 | 447 | /** 448 | * Standard deviation for a list of numbers 449 | */ 450 | private static stdDev(values: number[]): number { 451 | const avg = this.avg(values); 452 | 453 | const squareDiffs = values.map(function (value) { 454 | const diff = value - avg; 455 | return diff * diff; 456 | }); 457 | 458 | return Math.sqrt(this.avg(squareDiffs)); 459 | } 460 | } 461 | -------------------------------------------------------------------------------- /src/RecursivePartial.ts: -------------------------------------------------------------------------------- 1 | /** 2 | * Author: Meirion Hughes 3 | * @see https://stackoverflow.com/a/41980288/740183 4 | */ 5 | export type RecursivePartial = { 6 | [P in keyof T]?: RecursivePartial; 7 | }; 8 | -------------------------------------------------------------------------------- /src/index.ts: -------------------------------------------------------------------------------- 1 | export * from "./NtpTimeResult"; 2 | export * from "./NtpTimeSync"; 3 | -------------------------------------------------------------------------------- /tsconfig.json: -------------------------------------------------------------------------------- 1 | { 2 | "compilerOptions": { 3 | "outDir": "./dist", 4 | "allowJs": true, 5 | "lib": [ 6 | "es2019" 7 | ], 8 | "target": "es5", 9 | "noEmitOnError": true, 10 | "noImplicitAny": true, 11 | "noImplicitReturns": true, 12 | "declaration": true 13 | }, 14 | "include": [ 15 | "./src/**/*" 16 | ] 17 | } 18 | -------------------------------------------------------------------------------- /yarn.lock: -------------------------------------------------------------------------------- 1 | # THIS IS AN AUTOGENERATED FILE. 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