WebNTP

WebNTP is NTP(-like) service via HTTP/WebSocket.

Synopsis

First, go install and start the WebNTP Server.

$ go install github.com/shogo82148/go-webntp/cmd/webntp
$ webntp -serve :8080

Sync with the server via HTTP.

$ webntp http://localhost:8080/
server http://localhost:8080/, offset -0.000066, delay 0.001453
2017-03-11 18:25:10.905049427 +0900 JST, server http://localhost:8080/, offset -0.000066

Sync with the server via WebSocket.

$ webntp ws://localhost:8080/
server ws://localhost:8080/, offset -0.000013, delay 0.000288
2017-03-11 18:25:36.668531757 +0900 JST, server ws://localhost:8080/, offset -0.000013

I provide a public WebNTP API.

$ webntp https://webntp.shogo82148.com/api
server https://webntp.shogo82148.com/api, offset -0.006376, delay 0.024411
2017-03-11 16:08:06.150393313 +0900 JST, server https://webntp.shogo82148.com/api, offset -0.006376

Shared Memory support for ntpd

Add a new server to your ntpd.conf.

server 127.127.28.2 noselect
fudge 127.127.28.2 refid PYTH stratum 10

Run WebNTP with -shm 2 option.

$ webntp -p 1 -shm 2 https://webntp.shogo82148.com/api
server https://webntp.shogo82148.com/api, offset -0.003258, delay 0.018910

ntpd starts syncing with WebNTP.

$ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 SHM(2)          .PYTH.          10 l    2   64   17    0.000   -3.331   0.384
*webntp.shogo82. .NICT.           1 u   58   64   37   10.280    1.494   2.028

Usage

$ webntp --help
  -allow-cross-origin
    	allow cross origin request
  -help
    	show help
  -leap-second-path string
    	path for leap-seconds.list cache (default "leap-seconds.list")
  -leap-second-url string
    	url for leap-seconds.list (default "https://www.ietf.org/timezones/data/leap-seconds.list")
  -p int
    	Specify the number of samples (default 4)
  -serve string
    	server host name
  -shm uint
    	ntpd shared-memory-segment

Protocol

JSON over HTTP

The WebNTP clients access to http://example.com/?<timestamp>, and then the WebNTP server returns the time information formatted by JSON.

• id: hostname of the server
• it: the client's timestamp of the request transmission
• st: the server's timestamp
• leap: the seconds of TAI - UTC (before next)
• next: the timestamp of the next or last leap second
• step: positive leap second: 1, negative leap second: -1

Example:

$ curl -s http://localhost:8080/?1489217288.328757 | jq .
{
  "id": "localhost:8080",
  "it": 1489217288.328757,
  "st": 1489224472.995564,
  "time": 1489224472.995564,
  "leap": 36,
  "next": 1483228800,
  "step": 1
}

It is based on the document of http/https service by NICT (the National Institute of Information and Communications Technology). (the content is written in Japanese)

JSON over WebSocket

The WebNTP clients send a message including timestamp, and then the WebNTP server returns the time information formatted by JSON. JSON format is same as HTTP response.

Example:

$ wscat --connect localhost:8080
connected (press CTRL+C to quit)
> 1558915619.944235
< {"id":"localhost:8080","it":1558915619.944235,"st":1558916776.363423,"time":1558916776.363423,"leap":36,"next":1483228800.000000,"step":1}

Time over HTTPS with Improved timekeeping response

The clients send HEAD /.well-known/time HTTP request, and then the server returns the timestamp in the response header.

X-HTTPSTIME: <timestamp>

Example:

$ curl -I localhost:8080
HTTP/1.1 204 No Content
X-Httpstime: 1558915632.285965
Date: Mon, 27 May 2019 00:07:12 GMT

It is based on Time over HTTPS specification.

License

This software is released under the MIT License, see LICENSE.

SEE ALSO

• Time over HTTPS
• htp
• http/httpsを利用した時刻配信(アーカイブ) (The time server using http/https (archived))