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