124 lines
4.3 KiB
Java
Executable File
124 lines
4.3 KiB
Java
Executable File
/*
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* Copyright 2001-2005 The Apache Software Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.net;
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import java.io.IOException;
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import java.net.DatagramPacket;
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import java.net.InetAddress;
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import java.util.Date;
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/***
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* The TimeUDPClient class is a UDP implementation of a client for the
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* Time protocol described in RFC 868. To use the class, merely
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* open a local datagram socket with
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* {@link org.apache.commons.net.DatagramSocketClient#open open }
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* and call {@link #getTime getTime } or
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* {@link #getTime getDate } to retrieve the time. Then call
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* {@link org.apache.commons.net.DatagramSocketClient#close close }
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* to close the connection properly. Unlike
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* {@link org.apache.commons.net.TimeTCPClient},
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* successive calls to {@link #getTime getTime } or
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* {@link #getDate getDate } are permitted
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* without re-establishing a connection. That is because UDP is a
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* connectionless protocol and the Time protocol is stateless.
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* <p>
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* <p>
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* @author Daniel F. Savarese
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* @see TimeTCPClient
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***/
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public final class TimeUDPClient extends DatagramSocketClient
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{
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/*** The default time port. It is set to 37 according to RFC 868. ***/
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public static final int DEFAULT_PORT = 37;
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/***
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* The number of seconds between 00:00 1 January 1900 and
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* 00:00 1 January 1970. This value can be useful for converting
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* time values to other formats.
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***/
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public static final long SECONDS_1900_TO_1970 = 2208988800L;
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private byte[] __dummyData = new byte[1];
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private byte[] __timeData = new byte[4];
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/***
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* Retrieves the time from the specified server and port and
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* returns it. The time is the number of seconds since
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* 00:00 (midnight) 1 January 1900 GMT, as specified by RFC 868.
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* This method reads the raw 32-bit big-endian
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* unsigned integer from the server, converts it to a Java long, and
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* returns the value.
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* <p>
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* @param host The address of the server.
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* @param port The port of the service.
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* @return The time value retrieved from the server.
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* @exception IOException If an error occurs while retrieving the time.
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***/
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public long getTime(InetAddress host, int port) throws IOException
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{
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long time;
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DatagramPacket sendPacket, receivePacket;
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sendPacket =
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new DatagramPacket(__dummyData, __dummyData.length, host, port);
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receivePacket = new DatagramPacket(__timeData, __timeData.length);
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_socket_.send(sendPacket);
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_socket_.receive(receivePacket);
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time = 0L;
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time |= (((__timeData[0] & 0xff) << 24) & 0xffffffffL);
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time |= (((__timeData[1] & 0xff) << 16) & 0xffffffffL);
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time |= (((__timeData[2] & 0xff) << 8) & 0xffffffffL);
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time |= ((__timeData[3] & 0xff) & 0xffffffffL);
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return time;
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}
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/*** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/
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public long getTime(InetAddress host) throws IOException
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{
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return getTime(host, DEFAULT_PORT);
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}
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/***
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* Retrieves the time from the server and returns a Java Date
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* containing the time converted to the local timezone.
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* <p>
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* @param host The address of the server.
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* @param port The port of the service.
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* @return A Date value containing the time retrieved from the server
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* converted to the local timezone.
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* @exception IOException If an error occurs while fetching the time.
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***/
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public Date getDate(InetAddress host, int port) throws IOException
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{
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return new Date((getTime(host, port) - SECONDS_1900_TO_1970)*1000L);
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}
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/*** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/
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public Date getDate(InetAddress host) throws IOException
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{
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return new Date((getTime(host, DEFAULT_PORT) -
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SECONDS_1900_TO_1970)*1000L);
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}
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}
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