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* Timestamper:

Browse Source 
- Move from core to router, leave stub in core
     so it doesn't break compatibility. This removes a
     thread in app context and prevents any app context from
     running NTP; external clients must use the time
     received from the router.
   - Increase query interval
This commit is contained in:
zzz
2012-05-30 20:03:30 +00:00
parent ddc329e8f1
commit f14ff31a20
12 changed files with 402 additions and 345 deletions
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10
router/java/src/net/i2p/router/RouterClock.java
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@@ -4,6 +4,8 @@ import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import net.i2p.data.DataHelper;
import net.i2p.router.time.RouterTimestamper;
import net.i2p.time.Timestamper;
import net.i2p.util.Clock;
import net.i2p.util.Log;
@@ -38,6 +40,7 @@ public class RouterClock extends Clock {
/** use system time for this */
private long _lastChanged;
private int _lastStratum;
private final Timestamper _timeStamper;
/**
* If the system clock shifts by this much,
@@ -56,8 +59,15 @@ public class RouterClock extends Clock {
_lastSlewed = System.currentTimeMillis();
_shiftListeners = new CopyOnWriteArraySet();
_lastShiftNanos = System.nanoTime();
_timeStamper = new RouterTimestamper(context, this);
}
/**
* The RouterTimestamper
*/
@Override
public Timestamper getTimestamper() { return _timeStamper; }
/**
* Specify how far away from the "correct" time the computer is - a positive
* value means that the system time is slow, while a negative value means the system time is fast.

2
router/java/src/net/i2p/router/RouterVersion.java
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@@ -18,7 +18,7 @@ public class RouterVersion {
/** deprecated */
public final static String ID = "Monotone";
public final static String VERSION = CoreVersion.VERSION;
public final static long BUILD = 6;
public final static long BUILD = 7;
/** for example "-test" */
public final static String EXTRA = "";

210
router/java/src/net/i2p/router/time/NtpClient.java Normal file
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@@ -0,0 +1,210 @@
package net.i2p.router.time;
/*
* Copyright (c) 2004, Adam Buckley
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of Adam Buckley nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collections;
/**
* NtpClient - an NTP client for Java. This program connects to an NTP server
* and prints the response to the console.
*
* The local clock offset calculation is implemented according to the SNTP
* algorithm specified in RFC 2030.
*
* Note that on windows platforms, the curent time-of-day timestamp is limited
* to an resolution of 10ms and adversely affects the accuracy of the results.
*
* @author Adam Buckley
* (minor refactoring by jrandom)
* @since 0.9.1 moved from net.i2p.time
*/
class NtpClient {
/** difference between the unix epoch and jan 1 1900 (NTP uses that) */
private final static double SECONDS_1900_TO_EPOCH = 2208988800.0;
private final static int NTP_PORT = 123;
/**
* Query the ntp servers, returning the current time from first one we find
*
* @return milliseconds since january 1, 1970 (UTC)
* @throws IllegalArgumentException if none of the servers are reachable
*/
public static long currentTime(String serverNames[]) {
if (serverNames == null)
throw new IllegalArgumentException("No NTP servers specified");
ArrayList names = new ArrayList(serverNames.length);
for (int i = 0; i < serverNames.length; i++)
names.add(serverNames[i]);
Collections.shuffle(names);
for (int i = 0; i < names.size(); i++) {
long now = currentTime((String)names.get(i));
if (now > 0)
return now;
}
throw new IllegalArgumentException("No reachable NTP servers specified");
}
/**
* Query the ntp servers, returning the current time from first one we find
* Hack to return time and stratum
* @return time in rv[0] and stratum in rv[1]
* @throws IllegalArgumentException if none of the servers are reachable
* @since 0.7.12
*/
public static long[] currentTimeAndStratum(String serverNames[]) {
if (serverNames == null)
throw new IllegalArgumentException("No NTP servers specified");
ArrayList names = new ArrayList(serverNames.length);
for (int i = 0; i < serverNames.length; i++)
names.add(serverNames[i]);
Collections.shuffle(names);
for (int i = 0; i < names.size(); i++) {
long[] rv = currentTimeAndStratum((String)names.get(i));
if (rv != null && rv[0] > 0)
return rv;
}
throw new IllegalArgumentException("No reachable NTP servers specified");
}
/**
* Query the given NTP server, returning the current internet time
*
* @return milliseconds since january 1, 1970 (UTC), or -1 on error
*/
public static long currentTime(String serverName) {
long[] la = currentTimeAndStratum(serverName);
if (la != null)
return la[0];
return -1;
}
/**
* Hack to return time and stratum
* @return time in rv[0] and stratum in rv[1], or null for error
* @since 0.7.12
*/
private static long[] currentTimeAndStratum(String serverName) {
try {
// Send request
DatagramSocket socket = new DatagramSocket();
InetAddress address = InetAddress.getByName(serverName);
byte[] buf = new NtpMessage().toByteArray();
DatagramPacket packet = new DatagramPacket(buf, buf.length, address, NTP_PORT);
// Set the transmit timestamp *just* before sending the packet
// ToDo: Does this actually improve performance or not?
NtpMessage.encodeTimestamp(packet.getData(), 40,
(System.currentTimeMillis()/1000.0)
+ SECONDS_1900_TO_EPOCH);
socket.send(packet);
// Get response
packet = new DatagramPacket(buf, buf.length);
socket.setSoTimeout(10*1000);
try {
socket.receive(packet);
} catch (InterruptedIOException iie) {
socket.close();
return null;
}
// Immediately record the incoming timestamp
double destinationTimestamp = (System.currentTimeMillis()/1000.0) + SECONDS_1900_TO_EPOCH;
// Process response
NtpMessage msg = new NtpMessage(packet.getData());
//double roundTripDelay = (destinationTimestamp-msg.originateTimestamp) -
// (msg.receiveTimestamp-msg.transmitTimestamp);
double localClockOffset = ((msg.receiveTimestamp - msg.originateTimestamp) +
(msg.transmitTimestamp - destinationTimestamp)) / 2;
socket.close();
// Stratum must be between 1 (atomic) and 15 (maximum defined value)
// Anything else is right out, treat such responses like errors
if ((msg.stratum < 1) || (msg.stratum > 15)) {
//System.out.println("Response from NTP server of unacceptable stratum " + msg.stratum + ", failing.");
return null;
}
long[] rv = new long[2];
rv[0] = (long)(System.currentTimeMillis() + localClockOffset*1000);
rv[1] = msg.stratum;
//System.out.println("host: " + address.getHostAddress() + " rtt: " + roundTripDelay + " offset: " + localClockOffset + " seconds");
return rv;
} catch (IOException ioe) {
//ioe.printStackTrace();
return null;
}
}
public static void main(String[] args) throws IOException {
// Process command-line args
if(args.length <= 0) {
printUsage();
return;
// args = new String[] { "ntp1.sth.netnod.se", "ntp2.sth.netnod.se" };
}
long now = currentTime(args);
System.out.println("Current time: " + new java.util.Date(now));
}
/**
* Prints usage
*/
static void printUsage() {
System.out.println(
"NtpClient - an NTP client for Java.\n" +
"\n" +
"This program connects to an NTP server and prints the current time to the console.\n" +
"\n" +
"\n" +
"Usage: java NtpClient server[ server]*\n" +
"\n" +
"\n" +
"This program is copyright (c) Adam Buckley 2004 and distributed under the terms\n" +
"of the GNU General Public License. This program is distributed in the hope\n" +
"that it will be useful, but WITHOUT ANY WARRANTY; without even the implied\n" +
"warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU\n" +
"General Public License available at http://www.gnu.org/licenses/gpl.html for\n" +
"more details.");
}
}

468
router/java/src/net/i2p/router/time/NtpMessage.java Normal file
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@@ -0,0 +1,468 @@
package net.i2p.router.time;
/*
* Copyright (c) 2004, Adam Buckley
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of Adam Buckley nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import net.i2p.util.RandomSource;
/**
* This class represents a NTP message, as specified in RFC 2030. The message
* format is compatible with all versions of NTP and SNTP.
*
* This class does not support the optional authentication protocol, and
* ignores the key ID and message digest fields.
*
* For convenience, this class exposes message values as native Java types, not
* the NTP-specified data formats. For example, timestamps are
* stored as doubles (as opposed to the NTP unsigned 64-bit fixed point
* format).
*
* However, the contructor NtpMessage(byte[]) and the method toByteArray()
* allow the import and export of the raw NTP message format.
*
*
* Usage example
*
* // Send message
* DatagramSocket socket = new DatagramSocket();
* InetAddress address = InetAddress.getByName("ntp.cais.rnp.br");
* byte[] buf = new NtpMessage().toByteArray();
* DatagramPacket packet = new DatagramPacket(buf, buf.length, address, 123);
* socket.send(packet);
*
* // Get response
* socket.receive(packet);
* System.out.println(msg.toString());
*
* Comments for member variables are taken from RFC2030 by David Mills,
* University of Delaware.
*
* Number format conversion code in NtpMessage(byte[] array) and toByteArray()
* inspired by http://www.pps.jussieu.fr/~jch/enseignement/reseaux/
* NTPMessage.java which is copyright (c) 2003 by Juliusz Chroboczek
*
* @author Adam Buckley
* @since 0.9.1 moved from net.i2p.time
*/
class NtpMessage {
/**
* This is a two-bit code warning of an impending leap second to be
* inserted/deleted in the last minute of the current day. It's values
* may be as follows:
*
* Value Meaning
* ----- -------
* 0 no warning
* 1 last minute has 61 seconds
* 2 last minute has 59 seconds)
* 3 alarm condition (clock not synchronized)
*/
public byte leapIndicator = 0;
/**
* This value indicates the NTP/SNTP version number. The version number
* is 3 for Version 3 (IPv4 only) and 4 for Version 4 (IPv4, IPv6 and OSI).
* If necessary to distinguish between IPv4, IPv6 and OSI, the
* encapsulating context must be inspected.
*/
public byte version = 3;
/**
* This value indicates the mode, with values defined as follows:
*
* Mode Meaning
* ---- -------
* 0 reserved
* 1 symmetric active
* 2 symmetric passive
* 3 client
* 4 server
* 5 broadcast
* 6 reserved for NTP control message
* 7 reserved for private use
*
* In unicast and anycast modes, the client sets this field to 3 (client)
* in the request and the server sets it to 4 (server) in the reply. In
* multicast mode, the server sets this field to 5 (broadcast).
*/
public byte mode = 0;
/**
* This value indicates the stratum level of the local clock, with values
* defined as follows:
*
* Stratum Meaning
* ----------------------------------------------
* 0 unspecified or unavailable
* 1 primary reference (e.g., radio clock)
* 2-15 secondary reference (via NTP or SNTP)
* 16-255 reserved
*/
public short stratum = 0;
/**
* This value indicates the maximum interval between successive messages,
* in seconds to the nearest power of two. The values that can appear in
* this field presently range from 4 (16 s) to 14 (16284 s); however, most
* applications use only the sub-range 6 (64 s) to 10 (1024 s).
*/
public byte pollInterval = 0;
/**
* This value indicates the precision of the local clock, in seconds to
* the nearest power of two. The values that normally appear in this field
* range from -6 for mains-frequency clocks to -20 for microsecond clocks
* found in some workstations.
*/
public byte precision = 0;
/**
* This value indicates the total roundtrip delay to the primary reference
* source, in seconds. Note that this variable can take on both positive
* and negative values, depending on the relative time and frequency
* offsets. The values that normally appear in this field range from
* negative values of a few milliseconds to positive values of several
* hundred milliseconds.
*/
public double rootDelay = 0;
/**
* This value indicates the nominal error relative to the primary reference
* source, in seconds. The values that normally appear in this field
* range from 0 to several hundred milliseconds.
*/
public double rootDispersion = 0;
/**
* This is a 4-byte array identifying the particular reference source.
* In the case of NTP Version 3 or Version 4 stratum-0 (unspecified) or
* stratum-1 (primary) servers, this is a four-character ASCII string, left
* justified and zero padded to 32 bits. In NTP Version 3 secondary
* servers, this is the 32-bit IPv4 address of the reference source. In NTP
* Version 4 secondary servers, this is the low order 32 bits of the latest
* transmit timestamp of the reference source. NTP primary (stratum 1)
* servers should set this field to a code identifying the external
* reference source according to the following list. If the external
* reference is one of those listed, the associated code should be used.
* Codes for sources not listed can be contrived as appropriate.
*
* Code External Reference Source
* ---- -------------------------
* LOCL uncalibrated local clock used as a primary reference for
* a subnet without external means of synchronization
* PPS atomic clock or other pulse-per-second source
* individually calibrated to national standards
* ACTS NIST dialup modem service
* USNO USNO modem service
* PTB PTB (Germany) modem service
* TDF Allouis (France) Radio 164 kHz
* DCF Mainflingen (Germany) Radio 77.5 kHz
* MSF Rugby (UK) Radio 60 kHz
* WWV Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz
* WWVB Boulder (US) Radio 60 kHz
* WWVH Kaui Hawaii (US) Radio 2.5, 5, 10, 15 MHz
* CHU Ottawa (Canada) Radio 3330, 7335, 14670 kHz
* LORC LORAN-C radionavigation system
* OMEG OMEGA radionavigation system
* GPS Global Positioning Service
* GOES Geostationary Orbit Environment Satellite
*/
public byte[] referenceIdentifier = {0, 0, 0, 0};
/**
* This is the time at which the local clock was last set or corrected, in
* seconds since 00:00 1-Jan-1900.
*/
public double referenceTimestamp = 0;
/**
* This is the time at which the request departed the client for the
* server, in seconds since 00:00 1-Jan-1900.
*/
public double originateTimestamp = 0;
/**
* This is the time at which the request arrived at the server, in seconds
* since 00:00 1-Jan-1900.
*/
public double receiveTimestamp = 0;
/**
* This is the time at which the reply departed the server for the client,
* in seconds since 00:00 1-Jan-1900.
*/
public double transmitTimestamp = 0;
/**
* Constructs a new NtpMessage from an array of bytes.
*/
public NtpMessage(byte[] array) {
// See the packet format diagram in RFC 2030 for details
leapIndicator = (byte) ((array[0] >> 6) & 0x3);
version = (byte) ((array[0] >> 3) & 0x7);
mode = (byte) (array[0] & 0x7);
stratum = unsignedByteToShort(array[1]);
pollInterval = array[2];
precision = array[3];
rootDelay = (array[4] * 256.0) +
unsignedByteToShort(array[5]) +
(unsignedByteToShort(array[6]) / 256.0) +
(unsignedByteToShort(array[7]) / 65536.0);
rootDispersion = (unsignedByteToShort(array[8]) * 256.0) +
unsignedByteToShort(array[9]) +
(unsignedByteToShort(array[10]) / 256.0) +
(unsignedByteToShort(array[11]) / 65536.0);
referenceIdentifier[0] = array[12];
referenceIdentifier[1] = array[13];
referenceIdentifier[2] = array[14];
referenceIdentifier[3] = array[15];
referenceTimestamp = decodeTimestamp(array, 16);
originateTimestamp = decodeTimestamp(array, 24);
receiveTimestamp = decodeTimestamp(array, 32);
transmitTimestamp = decodeTimestamp(array, 40);
}
/**
* Constructs a new NtpMessage in client -> server mode, and sets the
* transmit timestamp to the current time.
*/
public NtpMessage() {
// Note that all the other member variables are already set with
// appropriate default values.
this.mode = 3;
this.transmitTimestamp = (System.currentTimeMillis()/1000.0) + 2208988800.0;
}
/**
* This method constructs the data bytes of a raw NTP packet.
*/
public byte[] toByteArray() {
// All bytes are automatically set to 0
byte[] p = new byte[48];
p[0] = (byte) (leapIndicator << 6 | version << 3 | mode);
p[1] = (byte) stratum;
p[2] = pollInterval;
p[3] = precision;
// root delay is a signed 16.16-bit FP, in Java an int is 32-bits
int l = (int) (rootDelay * 65536.0);
p[4] = (byte) ((l >> 24) & 0xFF);
p[5] = (byte) ((l >> 16) & 0xFF);
p[6] = (byte) ((l >> 8) & 0xFF);
p[7] = (byte) (l & 0xFF);
// root dispersion is an unsigned 16.16-bit FP, in Java there are no
// unsigned primitive types, so we use a long which is 64-bits
long ul = (long) (rootDispersion * 65536.0);
p[8] = (byte) ((ul >> 24) & 0xFF);
p[9] = (byte) ((ul >> 16) & 0xFF);
p[10] = (byte) ((ul >> 8) & 0xFF);
p[11] = (byte) (ul & 0xFF);
p[12] = referenceIdentifier[0];
p[13] = referenceIdentifier[1];
p[14] = referenceIdentifier[2];
p[15] = referenceIdentifier[3];
encodeTimestamp(p, 16, referenceTimestamp);
encodeTimestamp(p, 24, originateTimestamp);
encodeTimestamp(p, 32, receiveTimestamp);
encodeTimestamp(p, 40, transmitTimestamp);
return p;
}
/**
* Returns a string representation of a NtpMessage
*/
@Override
public String toString() {
String precisionStr = new DecimalFormat("0.#E0").format(Math.pow(2, precision));
return "Leap indicator: " + leapIndicator + "\n" +
"Version: " + version + "\n" +
"Mode: " + mode + "\n" +
"Stratum: " + stratum + "\n" +
"Poll: " + pollInterval + "\n" +
"Precision: " + precision + " (" + precisionStr + " seconds)\n" +
"Root delay: " + new DecimalFormat("0.00").format(rootDelay*1000) + " ms\n" +
"Root dispersion: " + new DecimalFormat("0.00").format(rootDispersion*1000) + " ms\n" +
"Reference identifier: " + referenceIdentifierToString(referenceIdentifier, stratum, version) + "\n" +
"Reference timestamp: " + timestampToString(referenceTimestamp) + "\n" +
"Originate timestamp: " + timestampToString(originateTimestamp) + "\n" +
"Receive timestamp: " + timestampToString(receiveTimestamp) + "\n" +
"Transmit timestamp: " + timestampToString(transmitTimestamp);
}
/**
* Converts an unsigned byte to a short. By default, Java assumes that
* a byte is signed.
*/
public static short unsignedByteToShort(byte b) {
if((b & 0x80)==0x80)
return (short) (128 + (b & 0x7f));
else
return b;
}
/**
* Will read 8 bytes of a message beginning at <code>pointer</code>
* and return it as a double, according to the NTP 64-bit timestamp
* format.
*/
public static double decodeTimestamp(byte[] array, int pointer) {
double r = 0.0;
for(int i=0; i<8; i++) {
r += unsignedByteToShort(array[pointer+i]) * Math.pow(2, (3-i)*8);
}
return r;
}
/**
* Encodes a timestamp in the specified position in the message
*/
public static void encodeTimestamp(byte[] array, int pointer, double timestamp) {
// Converts a double into a 64-bit fixed point
for(int i=0; i<8; i++) {
// 2^24, 2^16, 2^8, .. 2^-32
double base = Math.pow(2, (3-i)*8);
// Capture byte value
array[pointer+i] = (byte) (timestamp / base);
// Subtract captured value from remaining total
timestamp = timestamp - (unsignedByteToShort(array[pointer+i]) * base);
}
// From RFC 2030: It is advisable to fill the non-significant
// low order bits of the timestamp with a random, unbiased
// bitstring, both to avoid systematic roundoff errors and as
// a means of loop detection and replay detection.
array[7+pointer] = (byte) (RandomSource.getInstance().nextInt());
}
/**
* Returns a timestamp (number of seconds since 00:00 1-Jan-1900) as a
* formatted date/time string.
*/
public static String timestampToString(double timestamp) {
if(timestamp==0) return "0";
// timestamp is relative to 1900, utc is used by Java and is relative
// to 1970
double utc = timestamp - (2208988800.0);
// milliseconds
long ms = (long) (utc * 1000.0);
// date/time
String date = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss").format(new Date(ms));
// fraction
double fraction = timestamp - ((long) timestamp);
String fractionSting = new DecimalFormat(".000000").format(fraction);
return date + fractionSting;
}
/**
* Returns a string representation of a reference identifier according
* to the rules set out in RFC 2030.
*/
public static String referenceIdentifierToString(byte[] ref, short stratum, byte version) {
// From the RFC 2030:
// In the case of NTP Version 3 or Version 4 stratum-0 (unspecified)
// or stratum-1 (primary) servers, this is a four-character ASCII
// string, left justified and zero padded to 32 bits.
if(stratum==0 || stratum==1) {
return new String(ref);
}
// In NTP Version 3 secondary servers, this is the 32-bit IPv4
// address of the reference source.
else if(version==3) {
return unsignedByteToShort(ref[0]) + "." +
unsignedByteToShort(ref[1]) + "." +
unsignedByteToShort(ref[2]) + "." +
unsignedByteToShort(ref[3]);
}
// In NTP Version 4 secondary servers, this is the low order 32 bits
// of the latest transmit timestamp of the reference source.
else if(version==4) {
return "" + ((unsignedByteToShort(ref[0]) / 256.0) +
(unsignedByteToShort(ref[1]) / 65536.0) +
(unsignedByteToShort(ref[2]) / 16777216.0) +
(unsignedByteToShort(ref[3]) / 4294967296.0));
}
return "";
}
}

340
router/java/src/net/i2p/router/time/RouterTimestamper.java Normal file
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@@ -0,0 +1,340 @@
package net.i2p.router.time;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.concurrent.CopyOnWriteArrayList;
import net.i2p.I2PAppContext;
import net.i2p.time.Timestamper;
import net.i2p.util.I2PThread;
import net.i2p.util.Log;
/**
* Periodically query a series of NTP servers and update any associated
* listeners. It tries the NTP servers in order, contacting them using
* SNTP (UDP port 123).
*
* @since 0.9.1 moved from net.i2p.time
*/
public class RouterTimestamper extends Timestamper {
private final I2PAppContext _context;
private Log _log;
private final List<String> _servers;
private List<String> _priorityServers;
private final List<UpdateListener> _listeners;
private int _queryFrequency;
private int _concurringServers;
private int _consecutiveFails;
private volatile boolean _disabled;
private final boolean _daemon;
private boolean _initialized;
private boolean _wellSynced;
private volatile boolean _isRunning;
private Thread _timestamperThread;
private static final int MIN_QUERY_FREQUENCY = 5*60*1000;
private static final int DEFAULT_QUERY_FREQUENCY = 11*60*1000;
private static final String DEFAULT_SERVER_LIST = "0.pool.ntp.org,1.pool.ntp.org,2.pool.ntp.org";
private static final String DEFAULT_DISABLED = "true";
/** how many times do we have to query if we are changing the clock? */
private static final int DEFAULT_CONCURRING_SERVERS = 3;
private static final int MAX_CONSECUTIVE_FAILS = 10;
public static final String PROP_QUERY_FREQUENCY = "time.queryFrequencyMs";
public static final String PROP_SERVER_LIST = "time.sntpServerList";
public static final String PROP_DISABLED = "time.disabled";
public static final String PROP_CONCURRING_SERVERS = "time.concurringServers";
public static final String PROP_IP_COUNTRY = "i2np.lastCountry";
/** if different SNTP servers differ by more than 10s, someone is b0rked */
private static final int MAX_VARIANCE = 10*1000;
public RouterTimestamper(I2PAppContext ctx) {
this(ctx, null, true);
}
public RouterTimestamper(I2PAppContext ctx, UpdateListener lsnr) {
this(ctx, lsnr, true);
}
public RouterTimestamper(I2PAppContext ctx, UpdateListener lsnr, boolean daemon) {
super();
// moved here to prevent problems with synchronized statements.
_servers = new ArrayList(3);
_listeners = new CopyOnWriteArrayList();
_context = ctx;
_daemon = daemon;
// DO NOT initialize _log here, stack overflow via LogManager init loop
// Don't bother starting a thread if we are disabled.
// This means we no longer check every 5 minutes to see if we got enabled,
// so the property must be set at startup.
// We still need to be instantiated since the router calls clock().getTimestamper().waitForInitialization()
String disabled = ctx.getProperty(PROP_DISABLED, DEFAULT_DISABLED);
if (Boolean.valueOf(disabled).booleanValue()) {
_initialized = true;
return;
}
if (lsnr != null)
_listeners.add(lsnr);
updateConfig();
startTimestamper();
}
public int getServerCount() {
synchronized (_servers) {
return _servers.size();
}
}
public String getServer(int index) {
synchronized (_servers) {
return _servers.get(index);
}
}
public int getQueryFrequencyMs() { return _queryFrequency; }
public boolean getIsDisabled() { return _disabled; }
public void addListener(UpdateListener lsnr) {
_listeners.add(lsnr);
}
public void removeListener(UpdateListener lsnr) {
_listeners.remove(lsnr);
}
public int getListenerCount() {
return _listeners.size();
}
public UpdateListener getListener(int index) {
return _listeners.get(index);
}
private void startTimestamper() {
_timestamperThread = new I2PThread(this, "Timestamper", _daemon);
_timestamperThread.setPriority(I2PThread.MIN_PRIORITY);
_isRunning = true;
_timestamperThread.start();
_context.addShutdownTask(new Shutdown());
}
@Override
public void waitForInitialization() {
try {
synchronized (this) {
if (!_initialized)
wait();
}
} catch (InterruptedException ie) {}
}
/**
* Update the time immediately.
* @since 0.8.8
*/
@Override
public void timestampNow() {
if (_initialized && _isRunning && (!_disabled) && _timestamperThread != null)
_timestamperThread.interrupt();
}
/** @since 0.8.8 */
private class Shutdown implements Runnable {
public void run() {
_isRunning = false;
if (_timestamperThread != null)
_timestamperThread.interrupt();
}
}
@Override
public void run() {
try { Thread.sleep(1000); } catch (InterruptedException ie) {}
_log = _context.logManager().getLog(Timestamper.class);
if (_log.shouldLog(Log.INFO))
_log.info("Starting timestamper");
boolean lastFailed = false;
try {
while (_isRunning) {
updateConfig();
if (!_disabled) {
// first the servers for our country, if we know what country we're in...
if (_priorityServers != null) {
if (_log.shouldLog(Log.DEBUG))
_log.debug("Querying servers " + _priorityServers);
try {
lastFailed = !queryTime(_priorityServers.toArray(new String[_priorityServers.size()]));
} catch (IllegalArgumentException iae) {
if ( (!lastFailed) && (_log.shouldLog(Log.WARN)) )
_log.warn("Unable to reach country-specific NTP servers");
lastFailed = true;
}
}
// ... and then the global list, if that failed
if (_priorityServers == null || lastFailed) {
if (_log.shouldLog(Log.DEBUG))
_log.debug("Querying servers " + _servers);
try {
lastFailed = !queryTime(_servers.toArray(new String[_servers.size()]));
} catch (IllegalArgumentException iae) {
if ( (!_initialized) && (_log.shouldLog(Log.ERROR)) ) {
List<String> all = new ArrayList();
if (_priorityServers != null)
all.addAll(_priorityServers);
all.addAll(_servers);
_log.error("Unable to reach any of the NTP servers " + all + " - network disconnected? Or set time.sntpServerList=myserver1.com,myserver2.com in advanced configuration.");
}
lastFailed = true;
}
}
}
_initialized = true;
synchronized (this) { notifyAll(); }
long sleepTime;
if (lastFailed) {
if (++_consecutiveFails >= MAX_CONSECUTIVE_FAILS)
sleepTime = 30*60*1000;
else
sleepTime = 30*1000;
} else {
_consecutiveFails = 0;
sleepTime = _context.random().nextInt(_queryFrequency / 2) + _queryFrequency;
if (_wellSynced)
sleepTime *= 3;
}
try { Thread.sleep(sleepTime); } catch (InterruptedException ie) {}
}
} catch (Throwable t) {
_log.log(Log.CRIT, "Timestamper died!", t);
synchronized (this) { notifyAll(); }
}
}
/**
* True if the time was queried successfully, false if it couldn't be
*/
private boolean queryTime(String serverList[]) throws IllegalArgumentException {
long found[] = new long[_concurringServers];
long now = -1;
int stratum = -1;
long expectedDelta = 0;
_wellSynced = false;
for (int i = 0; i < _concurringServers; i++) {
if (i > 0) {
// this delays startup when net is disconnected or the timeserver list is bad, don't make it too long
try { Thread.sleep(2*1000); } catch (InterruptedException ie) {}
}
long[] timeAndStratum = NtpClient.currentTimeAndStratum(serverList);
now = timeAndStratum[0];
stratum = (int) timeAndStratum[1];
long delta = now - _context.clock().now();
found[i] = delta;
if (i == 0) {
if (Math.abs(delta) < MAX_VARIANCE) {
if (_log.shouldLog(Log.INFO))
_log.info("a single SNTP query was within the tolerance (" + delta + "ms)");
// If less than a half second on the first try, we're in good shape
_wellSynced = Math.abs(delta) < 500;
break;
} else {
// outside the tolerance, lets iterate across the concurring queries
expectedDelta = delta;
}
} else {
if (Math.abs(delta - expectedDelta) > MAX_VARIANCE) {
if (_log.shouldLog(Log.ERROR)) {
StringBuilder err = new StringBuilder(96);
err.append("SNTP client variance exceeded at query ").append(i);
err.append(". expected = ");
err.append(expectedDelta);
err.append(", found = ");
err.append(delta);
err.append(" all deltas: ");
for (int j = 0; j < found.length; j++)
err.append(found[j]).append(' ');
_log.error(err.toString());
}
return false;
}
}
}
stampTime(now, stratum);
if (_log.shouldLog(Log.DEBUG)) {
StringBuilder buf = new StringBuilder(64);
buf.append("Deltas: ");
for (int i = 0; i < found.length; i++)
buf.append(found[i]).append(' ');
_log.debug(buf.toString());
}
return true;
}
/**
* Notify the listeners
*
* @since stratum param added in 0.7.12
*/
private void stampTime(long now, int stratum) {
long before = _context.clock().now();
for (UpdateListener lsnr : _listeners) {
lsnr.setNow(now, stratum);
}
if (_log.shouldLog(Log.DEBUG))
_log.debug("Stamped the time as " + now + " (delta=" + (now-before) + ")");
}
/**
* Reload all the config elements from the appContext
*
*/
private void updateConfig() {
String serverList = _context.getProperty(PROP_SERVER_LIST);
if ( (serverList == null) || (serverList.trim().length() <= 0) ) {
serverList = DEFAULT_SERVER_LIST;
String country = _context.getProperty(PROP_IP_COUNTRY);
if (country == null) {
country = Locale.getDefault().getCountry();
if (country != null)
country = country.toLowerCase(Locale.US);
}
if (country != null && country.length() > 0) {
_priorityServers = new ArrayList(3);
for (int i = 0; i < 3; i++)
_priorityServers.add(i + "." + country + ".pool.ntp.org");
} else {
_priorityServers = null;
}
} else {
_priorityServers = null;
}
_servers.clear();
StringTokenizer tok = new StringTokenizer(serverList, ", ");
while (tok.hasMoreTokens()) {
String val = tok.nextToken();
val = val.trim();
if (val.length() > 0)
_servers.add(val);
}
_queryFrequency = Math.max(MIN_QUERY_FREQUENCY,
_context.getProperty(PROP_QUERY_FREQUENCY, DEFAULT_QUERY_FREQUENCY));
String disabled = _context.getProperty(PROP_DISABLED, DEFAULT_DISABLED);
_disabled = Boolean.valueOf(disabled).booleanValue();
_concurringServers = Math.min(4, Math.max(1,
_context.getProperty(PROP_CONCURRING_SERVERS, DEFAULT_CONCURRING_SERVERS)));
}
/****
public static void main(String args[]) {
System.setProperty(PROP_DISABLED, "false");
System.setProperty(PROP_QUERY_FREQUENCY, "30000");
I2PAppContext.getGlobalContext();
for (int i = 0; i < 5*60*1000; i += 61*1000) {
try { Thread.sleep(61*1000); } catch (InterruptedException ie) {}
}
}
****/
}

7
router/java/src/net/i2p/router/time/package.html Normal file
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<html>
<body>
<p>
Provides classes for time synchronization using NTP.
</p>
</body>
</html>