--- /dev/null
+// Load modules
+
+var Dgram = require('dgram');
+var Dns = require('dns');
+var Hoek = require('hoek');
+
+
+// Declare internals
+
+var internals = {};
+
+
+exports.time = function (options, callback) {
+
+ if (arguments.length !== 2) {
+ callback = arguments[0];
+ options = {};
+ }
+
+ var settings = Hoek.clone(options);
+ settings.host = settings.host || 'pool.ntp.org';
+ settings.port = settings.port || 123;
+ settings.resolveReference = settings.resolveReference || false;
+
+ // Declare variables used by callback
+
+ var timeoutId = 0;
+ var sent = 0;
+
+ // Ensure callback is only called once
+
+ var finish = function (err, result) {
+
+ if (timeoutId) {
+ clearTimeout(timeoutId);
+ timeoutId = 0;
+ }
+
+ socket.removeAllListeners();
+ socket.once('error', internals.ignore);
+ socket.close();
+ return callback(err, result);
+ };
+
+ finish = Hoek.once(finish);
+
+ // Create UDP socket
+
+ var socket = Dgram.createSocket('udp4');
+
+ socket.once('error', function (err) {
+
+ return finish(err);
+ });
+
+ // Listen to incoming messages
+
+ socket.on('message', function (buffer, rinfo) {
+
+ var received = Date.now();
+
+ var message = new internals.NtpMessage(buffer);
+ if (!message.isValid) {
+ return finish(new Error('Invalid server response'), message);
+ }
+
+ if (message.originateTimestamp !== sent) {
+ return finish(new Error('Wrong originate timestamp'), message);
+ }
+
+ // Timestamp Name ID When Generated
+ // ------------------------------------------------------------
+ // Originate Timestamp T1 time request sent by client
+ // Receive Timestamp T2 time request received by server
+ // Transmit Timestamp T3 time reply sent by server
+ // Destination Timestamp T4 time reply received by client
+ //
+ // The roundtrip delay d and system clock offset t are defined as:
+ //
+ // d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2
+
+ var T1 = message.originateTimestamp;
+ var T2 = message.receiveTimestamp;
+ var T3 = message.transmitTimestamp;
+ var T4 = received;
+
+ message.d = (T4 - T1) - (T3 - T2);
+ message.t = ((T2 - T1) + (T3 - T4)) / 2;
+ message.receivedLocally = received;
+
+ if (!settings.resolveReference ||
+ message.stratum !== 'secondary') {
+
+ return finish(null, message);
+ }
+
+ // Resolve reference IP address
+
+ Dns.reverse(message.referenceId, function (err, domains) {
+
+ if (/* $lab:coverage:off$ */ !err /* $lab:coverage:on$ */) {
+ message.referenceHost = domains[0];
+ }
+
+ return finish(null, message);
+ });
+ });
+
+ // Set timeout
+
+ if (settings.timeout) {
+ timeoutId = setTimeout(function () {
+
+ timeoutId = 0;
+ return finish(new Error('Timeout'));
+ }, settings.timeout);
+ }
+
+ // Construct NTP message
+
+ var message = new Buffer(48);
+ for (var i = 0; i < 48; i++) { // Zero message
+ message[i] = 0;
+ }
+
+ message[0] = (0 << 6) + (4 << 3) + (3 << 0) // Set version number to 4 and Mode to 3 (client)
+ sent = Date.now();
+ internals.fromMsecs(sent, message, 40); // Set transmit timestamp (returns as originate)
+
+ // Send NTP request
+
+ socket.send(message, 0, message.length, settings.port, settings.host, function (err, bytes) {
+
+ if (err ||
+ bytes !== 48) {
+
+ return finish(err || new Error('Could not send entire message'));
+ }
+ });
+};
+
+
+internals.NtpMessage = function (buffer) {
+
+ this.isValid = false;
+
+ // Validate
+
+ if (buffer.length !== 48) {
+ return;
+ }
+
+ // Leap indicator
+
+ var li = (buffer[0] >> 6);
+ switch (li) {
+ case 0: this.leapIndicator = 'no-warning'; break;
+ case 1: this.leapIndicator = 'last-minute-61'; break;
+ case 2: this.leapIndicator = 'last-minute-59'; break;
+ case 3: this.leapIndicator = 'alarm'; break;
+ }
+
+ // Version
+
+ var vn = ((buffer[0] & 0x38) >> 3);
+ this.version = vn;
+
+ // Mode
+
+ var mode = (buffer[0] & 0x7);
+ switch (mode) {
+ case 1: this.mode = 'symmetric-active'; break;
+ case 2: this.mode = 'symmetric-passive'; break;
+ case 3: this.mode = 'client'; break;
+ case 4: this.mode = 'server'; break;
+ case 5: this.mode = 'broadcast'; break;
+ case 0:
+ case 6:
+ case 7: this.mode = 'reserved'; break;
+ }
+
+ // Stratum
+
+ var stratum = buffer[1];
+ if (stratum === 0) {
+ this.stratum = 'death';
+ }
+ else if (stratum === 1) {
+ this.stratum = 'primary';
+ }
+ else if (stratum <= 15) {
+ this.stratum = 'secondary';
+ }
+ else {
+ this.stratum = 'reserved';
+ }
+
+ // Poll interval (msec)
+
+ this.pollInterval = Math.round(Math.pow(2, buffer[2])) * 1000;
+
+ // Precision (msecs)
+
+ this.precision = Math.pow(2, buffer[3]) * 1000;
+
+ // Root delay (msecs)
+
+ var rootDelay = 256 * (256 * (256 * buffer[4] + buffer[5]) + buffer[6]) + buffer[7];
+ this.rootDelay = 1000 * (rootDelay / 0x10000);
+
+ // Root dispersion (msecs)
+
+ this.rootDispersion = ((buffer[8] << 8) + buffer[9] + ((buffer[10] << 8) + buffer[11]) / Math.pow(2, 16)) * 1000;
+
+ // Reference identifier
+
+ this.referenceId = '';
+ switch (this.stratum) {
+ case 'death':
+ case 'primary':
+ this.referenceId = String.fromCharCode(buffer[12]) + String.fromCharCode(buffer[13]) + String.fromCharCode(buffer[14]) + String.fromCharCode(buffer[15]);
+ break;
+ case 'secondary':
+ this.referenceId = '' + buffer[12] + '.' + buffer[13] + '.' + buffer[14] + '.' + buffer[15];
+ break;
+ }
+
+ // Reference timestamp
+
+ this.referenceTimestamp = internals.toMsecs(buffer, 16);
+
+ // Originate timestamp
+
+ this.originateTimestamp = internals.toMsecs(buffer, 24);
+
+ // Receive timestamp
+
+ this.receiveTimestamp = internals.toMsecs(buffer, 32);
+
+ // Transmit timestamp
+
+ this.transmitTimestamp = internals.toMsecs(buffer, 40);
+
+ // Validate
+
+ if (this.version === 4 &&
+ this.stratum !== 'reserved' &&
+ this.mode === 'server' &&
+ this.originateTimestamp &&
+ this.receiveTimestamp &&
+ this.transmitTimestamp) {
+
+ this.isValid = true;
+ }
+
+ return this;
+};
+
+
+internals.toMsecs = function (buffer, offset) {
+
+ var seconds = 0;
+ var fraction = 0;
+
+ for (var i = 0; i < 4; ++i) {
+ seconds = (seconds * 256) + buffer[offset + i];
+ }
+
+ for (i = 4; i < 8; ++i) {
+ fraction = (fraction * 256) + buffer[offset + i];
+ }
+
+ return ((seconds - 2208988800 + (fraction / Math.pow(2, 32))) * 1000);
+};
+
+
+internals.fromMsecs = function (ts, buffer, offset) {
+
+ var seconds = Math.floor(ts / 1000) + 2208988800;
+ var fraction = Math.round((ts % 1000) / 1000 * Math.pow(2, 32));
+
+ buffer[offset + 0] = (seconds & 0xFF000000) >> 24;
+ buffer[offset + 1] = (seconds & 0x00FF0000) >> 16;
+ buffer[offset + 2] = (seconds & 0x0000FF00) >> 8;
+ buffer[offset + 3] = (seconds & 0x000000FF);
+
+ buffer[offset + 4] = (fraction & 0xFF000000) >> 24;
+ buffer[offset + 5] = (fraction & 0x00FF0000) >> 16;
+ buffer[offset + 6] = (fraction & 0x0000FF00) >> 8;
+ buffer[offset + 7] = (fraction & 0x000000FF);
+};
+
+
+// Offset singleton
+
+internals.last = {
+ offset: 0,
+ expires: 0,
+ host: '',
+ port: 0
+};
+
+
+exports.offset = function (options, callback) {
+
+ if (arguments.length !== 2) {
+ callback = arguments[0];
+ options = {};
+ }
+
+ var now = Date.now();
+ var clockSyncRefresh = options.clockSyncRefresh || 24 * 60 * 60 * 1000; // Daily
+
+ if (internals.last.offset &&
+ internals.last.host === options.host &&
+ internals.last.port === options.port &&
+ now < internals.last.expires) {
+
+ process.nextTick(function () {
+
+ callback(null, internals.last.offset);
+ });
+
+ return;
+ }
+
+ exports.time(options, function (err, time) {
+
+ if (err) {
+ return callback(err, 0);
+ }
+
+ internals.last = {
+ offset: Math.round(time.t),
+ expires: now + clockSyncRefresh,
+ host: options.host,
+ port: options.port
+ };
+
+ return callback(null, internals.last.offset);
+ });
+};
+
+
+// Now singleton
+
+internals.now = {
+ intervalId: 0
+};
+
+
+exports.start = function (options, callback) {
+
+ if (arguments.length !== 2) {
+ callback = arguments[0];
+ options = {};
+ }
+
+ if (internals.now.intervalId) {
+ process.nextTick(function () {
+
+ callback();
+ });
+
+ return;
+ }
+
+ exports.offset(options, function (err, offset) {
+
+ internals.now.intervalId = setInterval(function () {
+
+ exports.offset(options, function () { });
+ }, options.clockSyncRefresh || 24 * 60 * 60 * 1000); // Daily
+
+ return callback();
+ });
+};
+
+
+exports.stop = function () {
+
+ if (!internals.now.intervalId) {
+ return;
+ }
+
+ clearInterval(internals.now.intervalId);
+ internals.now.intervalId = 0;
+};
+
+
+exports.isLive = function () {
+
+ return !!internals.now.intervalId;
+};
+
+
+exports.now = function () {
+
+ var now = Date.now();
+ if (!exports.isLive() ||
+ now >= internals.last.expires) {
+
+ return now;
+ }
+
+ return now + internals.last.offset;
+};
+
+
+internals.ignore = function () {
+
+};
Code Review / simantics / district.git / blobdiff