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joplin/ReactNativeClient/lib/vendor/ntp-client.js
2020-09-09 00:34:27 +01:00

148 lines
4.7 KiB
JavaScript

/*
* ntp-client
* https://github.com/moonpyk/node-ntp-client
*
* Copyright (c) 2013 Clément Bourgeois
* Licensed under the MIT license.
*/
// ----------------------------------------------------------------------------------------
// 2020-08-09: We vendor the package because although it works
// it has several bugs and is currently unmaintained
// ----------------------------------------------------------------------------------------
(function (exports) {
"use strict";
exports.defaultNtpPort = 123;
exports.defaultNtpServer = "pool.ntp.org";
exports.dgram = null;
/**
* Amount of acceptable time to await for a response from the remote server.
* Configured default to 10 seconds.
*/
exports.ntpReplyTimeout = 10000;
/**
* Fetches the current NTP Time from the given server and port.
* @param {string} server IP/Hostname of the remote NTP Server
* @param {number} port Remote NTP Server port number
* @param {function(Object, Date)} callback(err, date) Async callback for
* the result date or eventually error.
*/
exports.getNetworkTime = function (server, port, callback) {
if (callback === null || typeof callback !== "function") {
return;
}
server = server || exports.defaultNtpServer;
port = port || exports.defaultNtpPort;
if (!exports.dgram) throw new Error('dgram package has not been set!!');
var client = exports.dgram.createSocket("udp4"),
ntpData = new Buffer(48);
// RFC 2030 -> LI = 0 (no warning, 2 bits), VN = 3 (IPv4 only, 3 bits), Mode = 3 (Client Mode, 3 bits) -> 1 byte
// -> rtol(LI, 6) ^ rotl(VN, 3) ^ rotl(Mode, 0)
// -> = 0x00 ^ 0x18 ^ 0x03
ntpData[0] = 0x1B;
for (var i = 1; i < 48; i++) {
ntpData[i] = 0;
}
// Some errors can happen before/after send() or cause send() to was impossible.
// Some errors will also be given to the send() callback.
// We keep a flag, therefore, to prevent multiple callbacks.
// NOTE : the error callback is not generalised, as the client has to lose the connection also, apparently.
var errorFired = false;
function closeClient(client) {
try {
client.close();
} catch (error) {
// Doesn't mater if it could not be closed
}
}
var timeout = setTimeout(function () {
closeClient(client);
if (errorFired) {
return;
}
callback(new Error("Timeout waiting for NTP response."), null);
errorFired = true;
}, exports.ntpReplyTimeout);
client.on('error', function (err) {
clearTimeout(timeout);
if (errorFired) {
return;
}
callback(err, null);
errorFired = true;
});
client.send(ntpData, 0, ntpData.length, port, server, function (err) {
if (err) {
clearTimeout(timeout);
if (errorFired) {
return;
}
callback(err, null);
errorFired = true;
closeClient(client);
return;
}
client.once('message', function (msg) {
clearTimeout(timeout);
closeClient(client);
// Offset to get to the "Transmit Timestamp" field (time at which the reply
// departed the server for the client, in 64-bit timestamp format."
var offsetTransmitTime = 40,
intpart = 0,
fractpart = 0;
// Get the seconds part
for (var i = 0; i <= 3; i++) {
intpart = 256 * intpart + msg[offsetTransmitTime + i];
}
// Get the seconds fraction
for (i = 4; i <= 7; i++) {
fractpart = 256 * fractpart + msg[offsetTransmitTime + i];
}
var milliseconds = (intpart * 1000 + (fractpart * 1000) / 0x100000000);
// **UTC** time
var date = new Date("Jan 01 1900 GMT");
date.setUTCMilliseconds(date.getUTCMilliseconds() + milliseconds);
callback(null, date);
});
});
};
exports.demo = function (argv) {
exports.getNetworkTime(
exports.defaultNtpServer,
exports.defaultNtpPort,
function (err, date) {
if (err) {
console.error(err);
return;
}
console.log(date);
});
};
}(exports));