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	/*
	* Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.net;

	/**
	* This class represents a datagram packet.
	* <p>
	* Datagram packets are used to implement a connectionless packet
	* delivery service. Each message is routed from one machine to
	* another based solely on information contained within that packet.
	* Multiple packets sent from one machine to another might be routed
	* differently, and might arrive in any order. Packet delivery is
	* not guaranteed.
	*
	* @author Pavani Diwanji
	* @author Benjamin Renaud
	* @since JDK1.0
	*/
	public final
	class DatagramPacket {

	/**
	* Perform class initialization
	*/
	static {
	java.security.AccessController.doPrivileged(
	new java.security.PrivilegedAction<Void>() {
	public Void run() {
	System.loadLibrary("net");
	return null;
	}
	});
	init();
	}

	/*
	* The fields of this class are package-private since DatagramSocketImpl
	* classes needs to access them.
	*/
	byte[] buf;
	int offset;
	int length;
	int bufLength;
	InetAddress address;
	int port;

	/**
	* Constructs a {@code DatagramPacket} for receiving packets of
	* length {@code length}, specifying an offset into the buffer.
	* <p>
	* The {@code length} argument must be less than or equal to
	* {@code buf.length}.
	*
	* @param buf buffer for holding the incoming datagram.
	* @param offset the offset for the buffer
	* @param length the number of bytes to read.
	*
	* @since 1.2
	*/
	public DatagramPacket(byte buf[], int offset, int length) {
	setData(buf, offset, length);
	this.address = null;
	this.port = -1;
	}

	/**
	* Constructs a {@code DatagramPacket} for receiving packets of
	* length {@code length}.
	* <p>
	* The {@code length} argument must be less than or equal to
	* {@code buf.length}.
	*
	* @param buf buffer for holding the incoming datagram.
	* @param length the number of bytes to read.
	*/
	public DatagramPacket(byte buf[], int length) {
	this (buf, 0, length);
	}

	/**
	* Constructs a datagram packet for sending packets of length
	* {@code length} with offset {@code ioffset}to the
	* specified port number on the specified host. The
	* {@code length} argument must be less than or equal to
	* {@code buf.length}.
	*
	* @param buf the packet data.
	* @param offset the packet data offset.
	* @param length the packet data length.
	* @param address the destination address.
	* @param port the destination port number.
	* @see java.net.InetAddress
	*
	* @since 1.2
	*/
	public DatagramPacket(byte buf[], int offset, int length,
	InetAddress address, int port) {
	setData(buf, offset, length);
	setAddress(address);
	setPort(port);
	}

	/**
	* Constructs a datagram packet for sending packets of length
	* {@code length} with offset {@code ioffset}to the
	* specified port number on the specified host. The
	* {@code length} argument must be less than or equal to
	* {@code buf.length}.
	*
	* @param buf the packet data.
	* @param offset the packet data offset.
	* @param length the packet data length.
	* @param address the destination socket address.
	* @throws IllegalArgumentException if address type is not supported
	* @see java.net.InetAddress
	*
	* @since 1.4
	*/
	public DatagramPacket(byte buf[], int offset, int length, SocketAddress address) {
	setData(buf, offset, length);
	setSocketAddress(address);
	}

	/**
	* Constructs a datagram packet for sending packets of length
	* {@code length} to the specified port number on the specified
	* host. The {@code length} argument must be less than or equal
	* to {@code buf.length}.
	*
	* @param buf the packet data.
	* @param length the packet length.
	* @param address the destination address.
	* @param port the destination port number.
	* @see java.net.InetAddress
	*/
	public DatagramPacket(byte buf[], int length,
	InetAddress address, int port) {
	this(buf, 0, length, address, port);
	}

	/**
	* Constructs a datagram packet for sending packets of length
	* {@code length} to the specified port number on the specified
	* host. The {@code length} argument must be less than or equal
	* to {@code buf.length}.
	*
	* @param buf the packet data.
	* @param length the packet length.
	* @param address the destination address.
	* @throws IllegalArgumentException if address type is not supported
	* @since 1.4
	* @see java.net.InetAddress
	*/
	public DatagramPacket(byte buf[], int length, SocketAddress address) {
	this(buf, 0, length, address);
	}

	/**
	* Returns the IP address of the machine to which this datagram is being
	* sent or from which the datagram was received.
	*
	* @return the IP address of the machine to which this datagram is being
	* sent or from which the datagram was received.
	* @see java.net.InetAddress
	* @see #setAddress(java.net.InetAddress)
	*/
	public synchronized InetAddress getAddress() {
	return address;
	}

	/**
	* Returns the port number on the remote host to which this datagram is
	* being sent or from which the datagram was received.
	*
	* @return the port number on the remote host to which this datagram is
	* being sent or from which the datagram was received.
	* @see #setPort(int)
	*/
	public synchronized int getPort() {
	return port;
	}

	/**
	* Returns the data buffer. The data received or the data to be sent
	* starts from the {@code offset} in the buffer,
	* and runs for {@code length} long.
	*
	* @return the buffer used to receive or send data
	* @see #setData(byte[], int, int)
	*/
	public synchronized byte[] getData() {
	return buf;
	}

	/**
	* Returns the offset of the data to be sent or the offset of the
	* data received.
	*
	* @return the offset of the data to be sent or the offset of the
	* data received.
	*
	* @since 1.2
	*/
	public synchronized int getOffset() {
	return offset;
	}

	/**
	* Returns the length of the data to be sent or the length of the
	* data received.
	*
	* @return the length of the data to be sent or the length of the
	* data received.
	* @see #setLength(int)
	*/
	public synchronized int getLength() {
	return length;
	}

	/**
	* Set the data buffer for this packet. This sets the
	* data, length and offset of the packet.
	*
	* @param buf the buffer to set for this packet
	*
	* @param offset the offset into the data
	*
	* @param length the length of the data
	* and/or the length of the buffer used to receive data
	*
	* @exception NullPointerException if the argument is null
	*
	* @see #getData
	* @see #getOffset
	* @see #getLength
	*
	* @since 1.2
	*/
	public synchronized void setData(byte[] buf, int offset, int length) {
	/* this will check to see if buf is null */
	if (length < 0 \|\| offset < 0 \|\|
	(length + offset) < 0 \|\|
	((length + offset) > buf.length)) {
	throw new IllegalArgumentException("illegal length or offset");
	}
	this.buf = buf;
	this.length = length;
	this.bufLength = length;
	this.offset = offset;
	}

	/**
	* Sets the IP address of the machine to which this datagram
	* is being sent.
	* @param iaddr the {@code InetAddress}
	* @since JDK1.1
	* @see #getAddress()
	*/
	public synchronized void setAddress(InetAddress iaddr) {
	address = iaddr;
	}

	/**
	* Sets the port number on the remote host to which this datagram
	* is being sent.
	* @param iport the port number
	* @since JDK1.1
	* @see #getPort()
	*/
	public synchronized void setPort(int iport) {
	if (iport < 0 \|\| iport > 0xFFFF) {
	throw new IllegalArgumentException("Port out of range:"+ iport);
	}
	port = iport;
	}

	/**
	* Sets the SocketAddress (usually IP address + port number) of the remote
	* host to which this datagram is being sent.
	*
	* @param address the {@code SocketAddress}
	* @throws IllegalArgumentException if address is null or is a
	* SocketAddress subclass not supported by this socket
	*
	* @since 1.4
	* @see #getSocketAddress
	*/
	public synchronized void setSocketAddress(SocketAddress address) {
	if (address == null \|\| !(address instanceof InetSocketAddress))
	throw new IllegalArgumentException("unsupported address type");
	InetSocketAddress addr = (InetSocketAddress) address;
	if (addr.isUnresolved())
	throw new IllegalArgumentException("unresolved address");
	setAddress(addr.getAddress());
	setPort(addr.getPort());
	}

	/**
	* Gets the SocketAddress (usually IP address + port number) of the remote
	* host that this packet is being sent to or is coming from.
	*
	* @return the {@code SocketAddress}
	* @since 1.4
	* @see #setSocketAddress
	*/
	public synchronized SocketAddress getSocketAddress() {
	return new InetSocketAddress(getAddress(), getPort());
	}

	/**
	* Set the data buffer for this packet. With the offset of
	* this DatagramPacket set to 0, and the length set to
	* the length of {@code buf}.
	*
	* @param buf the buffer to set for this packet.
	*
	* @exception NullPointerException if the argument is null.
	*
	* @see #getLength
	* @see #getData
	*
	* @since JDK1.1
	*/
	public synchronized void setData(byte[] buf) {
	if (buf == null) {
	throw new NullPointerException("null packet buffer");
	}
	this.buf = buf;
	this.offset = 0;
	this.length = buf.length;
	this.bufLength = buf.length;
	}

	/**
	* Set the length for this packet. The length of the packet is
	* the number of bytes from the packet's data buffer that will be
	* sent, or the number of bytes of the packet's data buffer that
	* will be used for receiving data. The length must be lesser or
	* equal to the offset plus the length of the packet's buffer.
	*
	* @param length the length to set for this packet.
	*
	* @exception IllegalArgumentException if the length is negative
	* of if the length is greater than the packet's data buffer
	* length.
	*
	* @see #getLength
	* @see #setData
	*
	* @since JDK1.1
	*/
	public synchronized void setLength(int length) {
	if ((length + offset) > buf.length \|\| length < 0 \|\|
	(length + offset) < 0) {
	throw new IllegalArgumentException("illegal length");
	}
	this.length = length;
	this.bufLength = this.length;
	}

	/**
	* Perform class load-time initializations.
	*/
	private native static void init();
	}

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