/*
* @(#)DatagramPacket.java 1.46 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
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
* @version 1.46, 04/07/06
* @since JDK1.0
*/
public final
class DatagramPacket {
/**
* Perform class initialization
*/
static {
java.security.AccessController.doPrivileged(
new sun.security.action.LoadLibraryAction("net"));
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</code> for receiving packets of
* length <code>length</code>, specifying an offset into the buffer.
* <p>
* The <code>length</code> argument must be less than or equal to
* <code>buf.length</code>.
*
* @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</code> for receiving packets of
* length <code>length</code>.
* <p>
* The <code>length</code> argument must be less than or equal to
* <code>buf.length</code>.
*
* @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</code> with offset <code>ioffset</code>to the
* specified port number on the specified host. The
* <code>length</code> argument must be less than or equal to
* <code>buf.length</code>.
*
* @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</code> with offset <code>ioffset</code>to the
* specified port number on the specified host. The
* <code>length</code> argument must be less than or equal to
* <code>buf.length</code>.
*
* @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) throws SocketException {
setData(buf, offset, length);
setSocketAddress(address);
}
/**
* Constructs a datagram packet for sending packets of length
* <code>length</code> to the specified port number on the specified
* host. The <code>length</code> argument must be less than or equal
* to <code>buf.length</code>.
*
* @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</code> to the specified port number on the specified
* host. The <code>length</code> argument must be less than or equal
* to <code>buf.length</code>.
*
* @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) throws SocketException {
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</code> in the buffer,
* and runs for <code>length</code> 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) > 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</code>
* @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</code>
* @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</code>
* @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</code>.
*
* @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) {
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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