/*
* @(#)DatagramSocket.java 1.6 95/12/02 Pavani Diwanji
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package java.net;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.lang.SecurityManager;
/**
* The datagram socket class implements unreliable datagrams.
* @author Pavani Diwanji
*/
public
class DatagramSocket {
private int localPort;
private FileDescriptor fd;
/**
* Load net library into runtime.
*/
static {
SecurityManager.setScopePermission();
System.loadLibrary("net");
}
/**
* Creates a datagram socket
*/
public DatagramSocket() throws SocketException {
// hack: why don't we require a security check here??
fd = new FileDescriptor();
// creates a udp socket
datagramSocketCreate();
// binds the udp socket to any local available port
localPort = datagramSocketBind(0);
}
/**
* Creates a datagram socket
* @param local port to use
*/
public DatagramSocket(int port) throws SocketException {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkListen(port);
}
fd = new FileDescriptor();
// creates a udp socket
datagramSocketCreate();
// binds the udp socket to desired port
localPort = datagramSocketBind(port);
}
/**
* Sends Datagram Packet to the destination address
* @param DatagramPacket to be sent. The packet contains the buffer
* of bytes, length and destination InetAddress and port.
* @exception IOException i/o error occurred
*/
public void send(DatagramPacket p) throws IOException {
// check the address is ok wiht the security manager on every send.
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkConnect(p.getAddress().getHostAddress(), p.getPort());
}
// call the native method to send
datagramSocketSend(p);
}
/**
* Receives datagram packet.
* @param DatagramPacket to be received.
* On return, the DatagramPacket contains the buffer in which the
* data is received, packet length, sender's address and sender's port
* number. Blocks until some input is available.
* @exception IOException i/o error occurred
*/
synchronized public void receive(DatagramPacket p) throws IOException {
InetAddress peekAddress = new InetAddress();
// peek at the packet to see who it is from.
int peekPort = datagramSocketPeek(peekAddress);
// check the address is ok with the security manager before every recv.
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkConnect(peekAddress.getHostAddress(), peekPort);
}
// If the security check succeeds, then receive the packet.
datagramSocketReceive(p);
return;
}
/**
* Returns the local port that this socket is bound to.
*/
public int getLocalPort() {
return localPort;
}
/**
* Close the datagram socket.
*/
public synchronized void close() {
datagramSocketClose();
}
protected synchronized void finalize() {
datagramSocketClose();
}
private native void datagramSocketCreate();
private native int datagramSocketBind(int port);
private native void datagramSocketSend(DatagramPacket p);
private native int datagramSocketPeek(InetAddress i);
private native void datagramSocketReceive(DatagramPacket p);
private native void datagramSocketClose();
// Hook to support multicast receives for @Home
private native void multicastJoinLeave(InetAddress inetaddr, boolean join);
}