gecko/toolkit/modules/Sntp.jsm
2016-02-03 17:27:36 -08:00

335 lines
9.6 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
this.EXPORTED_SYMBOLS = [
"Sntp",
];
const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
// Set to true to see debug messages.
var DEBUG = false;
/**
* Constructor of Sntp.
*
* @param dataAvailableCb
* Callback function gets called when SNTP offset available. Signature
* is function dataAvailableCb(offsetInMS).
* @param maxRetryCount
* Maximum retry count when SNTP failed to connect to server; set to
* zero to disable the retry.
* @param refreshPeriodInSecs
* Refresh period; set to zero to disable refresh.
* @param timeoutInSecs
* Timeout value used for connection.
* @param pools
* SNTP server lists separated by ';'.
* @param port
* SNTP port.
*/
this.Sntp = function Sntp(dataAvailableCb, maxRetryCount, refreshPeriodInSecs,
timeoutInSecs, pools, port) {
if (dataAvailableCb != null) {
this._dataAvailableCb = dataAvailableCb;
}
if (maxRetryCount != null) {
this._maxRetryCount = maxRetryCount;
}
if (refreshPeriodInSecs != null) {
this._refreshPeriodInMS = refreshPeriodInSecs * 1000;
}
if (timeoutInSecs != null) {
this._timeoutInMS = timeoutInSecs * 1000;
}
if (pools != null && Array.isArray(pools) && pools.length > 0) {
this._pools = pools;
}
if (port != null) {
this._port = port;
}
}
Sntp.prototype = {
isAvailable: function isAvailable() {
return this._cachedOffset != null;
},
isExpired: function isExpired() {
let valid = this._cachedOffset != null && this._cachedTimeInMS != null;
if (this._refreshPeriodInMS > 0) {
valid = valid && Date.now() < this._cachedTimeInMS +
this._refreshPeriodInMS;
}
return !valid;
},
request: function request() {
this._request();
},
getOffset: function getOffset() {
return this._cachedOffset;
},
/**
* Indicates the system clock has been changed by [offset]ms so we need to
* adjust the stored value.
*/
updateOffset: function updateOffset(offset) {
if (this._cachedOffset != null) {
this._cachedOffset -= offset;
}
},
/**
* Used to schedule a retry or periodic updates.
*/
_schedule: function _schedule(timeInMS) {
if (this._updateTimer == null) {
this._updateTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
}
this._updateTimer.initWithCallback(this._request.bind(this),
timeInMS,
Ci.nsITimer.TYPE_ONE_SHOT);
debug("Scheduled SNTP request in " + timeInMS + "ms");
},
/**
* Handle the SNTP response.
*/
_handleSntp: function _handleSntp(originateTimeInMS, receiveTimeInMS,
transmitTimeInMS, respondTimeInMS) {
let clockOffset = Math.floor(((receiveTimeInMS - originateTimeInMS) +
(transmitTimeInMS - respondTimeInMS)) / 2);
debug("Clock offset: " + clockOffset);
// We've succeeded so clear the retry status.
this._retryCount = 0;
this._retryPeriodInMS = 0;
// Cache the latest SNTP offset whenever receiving it.
this._cachedOffset = clockOffset;
this._cachedTimeInMS = respondTimeInMS;
if (this._dataAvailableCb != null) {
this._dataAvailableCb(clockOffset);
}
this._schedule(this._refreshPeriodInMS);
},
/**
* Used for retry SNTP requests.
*/
_retry: function _retry() {
this._retryCount++;
if (this._retryCount > this._maxRetryCount) {
debug ("stop retrying SNTP");
// Clear so we can start with clean status next time we have network.
this._retryCount = 0;
this._retryPeriodInMS = 0;
return;
}
this._retryPeriodInMS = Math.max(1000, this._retryPeriodInMS * 2);
this._schedule(this._retryPeriodInMS);
},
/**
* Request SNTP.
*/
_request: function _request() {
function GetRequest() {
let NTP_PACKET_SIZE = 48;
let NTP_MODE_CLIENT = 3;
let NTP_VERSION = 3;
let TRANSMIT_TIME_OFFSET = 40;
// Send the NTP request.
let requestTimeInMS = Date.now();
let s = requestTimeInMS / 1000;
let ms = requestTimeInMS % 1000;
// NTP time is relative to 1900.
s += OFFSET_1900_TO_1970;
let f = ms * 0x100000000 / 1000;
s = Math.floor(s);
f = Math.floor(f);
let buffer = new ArrayBuffer(NTP_PACKET_SIZE);
let data = new DataView(buffer);
data.setUint8(0, NTP_MODE_CLIENT | (NTP_VERSION << 3));
data.setUint32(TRANSMIT_TIME_OFFSET, s, false);
data.setUint32(TRANSMIT_TIME_OFFSET + 4, f, false);
return String.fromCharCode.apply(null, new Uint8Array(buffer));
}
function SNTPListener() {}
SNTPListener.prototype = {
onStartRequest: function onStartRequest(request, context) {
},
onStopRequest: function onStopRequest(request, context, status) {
if (!Components.isSuccessCode(status)) {
debug ("Connection failed");
this._requesting = false;
this._retry();
}
}.bind(this),
onDataAvailable: function onDataAvailable(request, context, inputStream,
offset, count) {
function GetTimeStamp(binaryInputStream) {
let s = binaryInputStream.read32();
let f = binaryInputStream.read32();
return Math.floor(
((s - OFFSET_1900_TO_1970) * 1000) + ((f * 1000) / 0x100000000)
);
}
debug ("Data available: " + count + " bytes");
try {
let binaryInputStream = Cc["@mozilla.org/binaryinputstream;1"]
.createInstance(Ci.nsIBinaryInputStream);
binaryInputStream.setInputStream(inputStream);
// We don't need first 24 bytes.
for (let i = 0; i < 6; i++) {
binaryInputStream.read32();
}
// Offset 24: originate time.
let originateTimeInMS = GetTimeStamp(binaryInputStream);
// Offset 32: receive time.
let receiveTimeInMS = GetTimeStamp(binaryInputStream);
// Offset 40: transmit time.
let transmitTimeInMS = GetTimeStamp(binaryInputStream);
let respondTimeInMS = Date.now();
this._handleSntp(originateTimeInMS, receiveTimeInMS,
transmitTimeInMS, respondTimeInMS);
this._requesting = false;
} catch (e) {
debug ("SNTPListener Error: " + e.message);
this._requesting = false;
this._retry();
}
inputStream.close();
}.bind(this)
};
function SNTPRequester() {}
SNTPRequester.prototype = {
onOutputStreamReady: function(stream) {
try {
let data = GetRequest();
let bytes_write = stream.write(data, data.length);
debug ("SNTP: sent " + bytes_write + " bytes");
stream.close();
} catch (e) {
debug ("SNTPRequester Error: " + e.message);
this._requesting = false;
this._retry();
}
}.bind(this)
};
// Number of seconds between Jan 1, 1900 and Jan 1, 1970.
// 70 years plus 17 leap days.
let OFFSET_1900_TO_1970 = ((365 * 70) + 17) * 24 * 60 * 60;
if (this._requesting) {
return;
}
if (this._pools.length < 1) {
debug("No server defined");
return;
}
if (this._updateTimer) {
this._updateTimer.cancel();
}
debug ("Making request");
this._requesting = true;
let currentThread = Cc["@mozilla.org/thread-manager;1"]
.getService().currentThread;
let socketTransportService =
Cc["@mozilla.org/network/socket-transport-service;1"]
.getService(Ci.nsISocketTransportService);
let pump = Cc["@mozilla.org/network/input-stream-pump;1"]
.createInstance(Ci.nsIInputStreamPump);
let transport = socketTransportService
.createTransport(["udp"],
1,
this._pools[Math.floor(this._pools.length * Math.random())],
this._port,
null);
transport.setTimeout(Ci.nsISocketTransport.TIMEOUT_CONNECT, this._timeoutInMS);
transport.setTimeout(Ci.nsISocketTransport.TIMEOUT_READ_WRITE, this._timeoutInMS);
let outStream = transport.openOutputStream(0, 0, 0)
.QueryInterface(Ci.nsIAsyncOutputStream);
let inStream = transport.openInputStream(0, 0, 0);
pump.init(inStream, -1, -1, 0, 0, false);
pump.asyncRead(new SNTPListener(), null);
outStream.asyncWait(new SNTPRequester(), 0, 0, currentThread);
},
// Callback function.
_dataAvailableCb: null,
// Sntp servers.
_pools: [
"0.pool.ntp.org",
"1.pool.ntp.org",
"2.pool.ntp.org",
"3.pool.ntp.org"
],
// The SNTP port.
_port: 123,
// Maximum retry count allowed when request failed.
_maxRetryCount: 0,
// Refresh period.
_refreshPeriodInMS: 0,
// Timeout value used for connecting.
_timeoutInMS: 30 * 1000,
// Cached SNTP offset.
_cachedOffset: null,
// The time point when we cache the offset.
_cachedTimeInMS: null,
// Flag to avoid redundant requests.
_requesting: false,
// Retry counter.
_retryCount: 0,
// Retry time offset (in seconds).
_retryPeriodInMS: 0,
// Timer used for retries & daily updates.
_updateTimer: null
};
var debug;
if (DEBUG) {
debug = function (s) {
dump("-*- Sntp: " + s + "\n");
};
} else {
debug = function (s) {};
}