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NTP packet parser

Library to parse NTP response packets according to RFC 5905 into a easy-to-use structure.
It does not apply any validations or calculations regarding the time but solely parses the data.

See buffcode/ntp-time-sync for an implementation.

Installation

``bash
yarn add ntp-packet-parser
`

Usage

$3

`js
import { NtpPacketParser } from "ntp-packet-parser";

/ const udpPacket = new Buffer(...); /
const result = NtpPacketParser.parse(udpPacket);
`

$3


`js
var NtpPacketParser = require("ntp-packet-parser").NtpPacketParser;

/ const udpPacket = new Buffer(...); /
var result = NtpPacketParser.parse(udpPacket);
`

Structure


The response from NtpPacketParser.parse will return the following object structure:

| Property | Type | Description |
| :--- | :--- | :--- |
| leapIndicator | Integer | Warning of an impending leap second to be inserted or deleted in the last minute of the current month |
| version | Integer | NTP version number, currently 4 |
| mode | Integer | Request/response mode |
| stratum | Integer | Stratum of the server |
| poll | Integer | Integer representing the maximum interval in log2 seconds between successive messages (Note: you need to apply Math.pow(2, ) to get the real value) |
| precision | Integer | Integer representing the precision of the system clock in log2 seconds (Note: you need to apply Math.pow(2, ) to get the real value) |
| rootDelay | Date | Total round-trip delay to the reference clock |
| rootDispersion | Date | Total dispersion to the reference clock |
| referenceId | String | String to identify the particular server or reference clock |
| referenceTimestamp | Date | Time when the system clock was last set or corrected |
| originTimestamp | Date | Time at the client when the request departed for the server |
| receiveTimestamp | Date | Time at the server when the request arrived from the client |
| transmitTimestamp | Date | Time at the server when the response left for the client |

To get the relative time for any Date property, calculate the difference between "Jan 01 1900 GMT" and the given date.

`js
let rootDelayInMilliseconds = result.rootDelay.getTime() - new Date("Jan 01 1900 GMT").getTime();
`

For further explanations on the possible values of these properties please refer to RFC 5909, Page 19ff.

Testing


Some tests regarding structure, response and error handling exist. To run them locally:
`js
yarn test
`

Contributing

Please file a PR against master`.

License

GNU General Public License Version 3