java.net
Class PlainDatagramSocketImpl

java.lang.Object
  java.net.DatagramSocketImpl
      java.net.PlainDatagramSocketImpl

All Implemented Interfaces:

SocketOptions

class PlainDatagramSocketImpl

extends DatagramSocketImpl

Concrete datagram and multicast socket implementation base class. Note: This is not a public class, so that applets cannot call into the implementation directly and hence cannot bypass the security checks present in the DatagramSocket and MulticastSocket classes.

Author:

Pavani Diwanji

Field Summary

private boolean	connected
private InetAddress	connectedAddress
private int	connectedPort
private boolean	loopbackMode
private int	multicastInterface
private int	timeout
private int	trafficClass
private int	ttl

Fields inherited from class java.net.DatagramSocketImpl

fd, localPort

Fields inherited from interface java.net.SocketOptions

IP_MULTICAST_IF, IP_MULTICAST_IF2, IP_MULTICAST_LOOP, IP_TOS, SO_BINDADDR, SO_BROADCAST, SO_KEEPALIVE, SO_LINGER, SO_OOBINLINE, SO_RCVBUF, SO_REUSEADDR, SO_SNDBUF, SO_TIMEOUT, TCP_NODELAY

Constructor Summary

(package private)

PlainDatagramSocketImpl()

Method Summary

protected void	bind(int lport, InetAddress laddr) Binds a datagram socket to a local port.
protected void	close() Close the socket.
protected void	connect(InetAddress address, int port) Connects a datagram socket to a remote destination.
private void	connect0(InetAddress address, int port)
protected void	create() Creates a datagram socket
private void	datagramSocketClose()
private void	datagramSocketCreate()
protected void	disconnect() Disconnects a previously connected socket.
private void	disconnect0()
protected void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
Object	getOption(int optID) Fetch the value of an option.
protected int	getTimeToLive() Get the TTL (time-to-live) option.
protected byte	getTTL() Get the TTL (time-to-live) option.
private static void	init() Perform class load-time initializations.
protected void	join(InetAddress inetaddr) Join the multicast group.
private void	join(InetAddress inetaddr, NetworkInterface netIf)
protected void	joinGroup(SocketAddress mcastaddr, NetworkInterface netIf) Join the multicast group.
protected void	leave(InetAddress inetaddr) Leave the multicast group.
private void	leave(InetAddress inetaddr, NetworkInterface netIf)
protected void	leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf) Leave the multicast group.
protected int	peek(InetAddress i) Peek at the packet to see who it is from.
protected int	peekData(DatagramPacket p) Peek at the packet to see who it is from.
protected void	receive(DatagramPacket p) Receive the datagram packet.
protected void	send(DatagramPacket p) Sends a datagram packet.
void	setOption(int optID, Object o) set a value - since we only support (setting) binary options here, o must be a Boolean
protected void	setTimeToLive(int ttl) Set the TTL (time-to-live) option.
protected void	setTTL(byte ttl) Set the TTL (time-to-live) option.
private Object	socketGetOption(int opt)
private void	socketSetOption(int opt, Object val)

Methods inherited from class java.net.DatagramSocketImpl

getFileDescriptor, getLocalPort

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

timeout

private int timeout

trafficClass

private int trafficClass

connected

private boolean connected

connectedAddress

private InetAddress connectedAddress

connectedPort

private int connectedPort

multicastInterface

private int multicastInterface

loopbackMode

private boolean loopbackMode

ttl

private int ttl

Constructor Detail

PlainDatagramSocketImpl

PlainDatagramSocketImpl()

Method Detail

create

protected void create()
               throws SocketException

Creates a datagram socket

Specified by:

create in class DatagramSocketImpl

Throws:

SocketException - if there is an error in the underlying protocol, such as a TCP error.

bind

protected void bind(int lport,
                    InetAddress laddr)
             throws SocketException

Binds a datagram socket to a local port.

Specified by:

bind in class DatagramSocketImpl

Parameters:

lport - the local port

laddr - the local address

Throws:

SocketException - if there is an error in the underlying protocol, such as a TCP error.

send

protected void send(DatagramPacket p)
             throws IOException

Sends a datagram packet. The packet contains the data and the destination address to send the packet to.

Specified by:

send in class DatagramSocketImpl

Parameters:

p - the packet to be sent.

Throws:

IOException - if an I/O exception occurs while sending the datagram packet.

connect

protected void connect(InetAddress address,
                       int port)
                throws SocketException

Connects a datagram socket to a remote destination. This associates the remote address with the local socket so that datagrams may only be sent to this destination and received from this destination.

Overrides:

connect in class DatagramSocketImpl

Parameters:

address - the remote InetAddress to connect to

port - the remote port number

Throws:

SocketException - may be thrown if the socket cannot be connected to the remote destination

disconnect

protected void disconnect()

Disconnects a previously connected socket. Does nothing if the socket was not connected already.

Overrides:

disconnect in class DatagramSocketImpl

peek

protected int peek(InetAddress i)
            throws IOException

Peek at the packet to see who it is from.

Specified by:

peek in class DatagramSocketImpl

Parameters:

i - an InetAddress object

Returns:

the address which the packet came from.

Throws:

IOException - if an I/O exception occurs

peekData

protected int peekData(DatagramPacket p)
                throws IOException

Description copied from class: DatagramSocketImpl

Peek at the packet to see who it is from. The data is returned, but not consumed, so that a subsequent peekData/receive operation will see the same data.

Specified by:

peekData in class DatagramSocketImpl

Parameters:

p - the Packet Received.

Returns:

the address which the packet came from.

Throws:

IOException - if an I/O exception occurs

receive

protected void receive(DatagramPacket p)
                throws IOException

Receive the datagram packet.

Specified by:

receive in class DatagramSocketImpl

Parameters:

p - the Packet Received.

Throws:

IOException - if an I/O exception occurs while receiving the datagram packet.

setTimeToLive

protected void setTimeToLive(int ttl)
                      throws IOException

Set the TTL (time-to-live) option.

Specified by:

setTimeToLive in class DatagramSocketImpl

Parameters:

ttl - an int specifying the time-to-live value

Throws:

IOException - if an I/O exception occurs while setting the time-to-live option.

See Also:

DatagramSocketImpl.getTimeToLive()

getTimeToLive

protected int getTimeToLive()
                     throws IOException

Get the TTL (time-to-live) option.

Specified by:

getTimeToLive in class DatagramSocketImpl

Returns:

an int representing the time-to-live value

Throws:

IOException - if an I/O exception occurs while retrieving the time-to-live option

See Also:

DatagramSocketImpl.setTimeToLive(int)

setTTL

protected void setTTL(byte ttl)
               throws IOException

Set the TTL (time-to-live) option.

Specified by:

setTTL in class DatagramSocketImpl

Parameters:

ttl - a byte specifying the TTL value

Throws:

IOException - if an I/O exception occurs while setting the time-to-live option.

See Also:

DatagramSocketImpl.getTTL()

getTTL

protected byte getTTL()
               throws IOException

Get the TTL (time-to-live) option.

Specified by:

getTTL in class DatagramSocketImpl

Returns:

a byte representing the TTL value

Throws:

IOException - if an I/O exception occurs while retrieving the time-to-live option

See Also:

DatagramSocketImpl.setTTL(byte)

join

protected void join(InetAddress inetaddr)
             throws IOException

Join the multicast group.

Specified by:

join in class DatagramSocketImpl

Parameters:

inetaddr - multicast address to join.

Throws:

IOException - if an I/O exception occurs while joining the multicast group.

leave

protected void leave(InetAddress inetaddr)
              throws IOException

Leave the multicast group.

Specified by:

leave in class DatagramSocketImpl

Parameters:

inetaddr - multicast address to leave.

Throws:

IOException - if an I/O exception occurs while leaving the multicast group.

joinGroup

protected void joinGroup(SocketAddress mcastaddr,
                         NetworkInterface netIf)
                  throws IOException

Join the multicast group.

Specified by:

joinGroup in class DatagramSocketImpl

Parameters:

netIf - specifies the local interface to receive multicast datagram packets

mcastaddr - address to join.

Throws:

IllegalArgumentException - if mcastaddr is null or is a SocketAddress subclass not supported by this socket

IOException - if an I/O exception occurs while joining the multicast group

Since:

1.4

join

private void join(InetAddress inetaddr,
                  NetworkInterface netIf)
           throws IOException

Throws:

IOException

leaveGroup

protected void leaveGroup(SocketAddress mcastaddr,
                          NetworkInterface netIf)
                   throws IOException

Leave the multicast group.

Specified by:

leaveGroup in class DatagramSocketImpl

Parameters:

netIf - specified the local interface to leave the group at

mcastaddr - address to leave.

Throws:

IllegalArgumentException - if mcastaddr is null or is a SocketAddress subclass not supported by this socket

IOException - if an I/O exception occurs while leaving the multicast group

Since:

1.4

leave

private void leave(InetAddress inetaddr,
                   NetworkInterface netIf)
            throws IOException

Throws:

IOException

close

protected void close()

Close the socket.

Specified by:

close in class DatagramSocketImpl

finalize

protected void finalize()

Description copied from class: Object

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java^TM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.

Overrides:

finalize in class Object

setOption

public void setOption(int optID,
                      Object o)
               throws SocketException

set a value - since we only support (setting) binary options here, o must be a Boolean

Parameters:

optID - identifies the option

o - the parameter of the socket option

Throws:

SocketException - if the option is unrecognized, the socket is closed, or some low-level error occurred

See Also:

SocketOptions.getOption(int)

getOption

public Object getOption(int optID)
                 throws SocketException

Description copied from interface: SocketOptions

Fetch the value of an option. Binary options will return java.lang.Boolean(true) if enabled, java.lang.Boolean(false) if disabled, e.g.:

 SocketImpl s;
 ...
 Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
 if (noDelay.booleanValue()) {
     // true if TCP_NODELAY is enabled...
 ...
 }
 

For options that take a particular type as a parameter, getOption(int) will return the paramter's value, else it will return java.lang.Boolean(false):

 Object o = s.getOption(SO_LINGER);
 if (o instanceof Integer) {
     System.out.print("Linger time is " + ((Integer)o).intValue());
 } else {
   // the true type of o is java.lang.Boolean(false);
 }
 

Parameters:

optID - an int identifying the option to fetch

Returns:

the value of the option

Throws:

SocketException - if optID is unknown along the protocol stack (including the SocketImpl)

See Also:

SocketOptions.setOption(int, java.lang.Object)

datagramSocketCreate

private void datagramSocketCreate()
                           throws SocketException

Throws:

SocketException

datagramSocketClose

private void datagramSocketClose()

socketSetOption

private void socketSetOption(int opt,
                             Object val)
                      throws SocketException

Throws:

SocketException

socketGetOption

private Object socketGetOption(int opt)
                        throws SocketException

Throws:

SocketException

connect0

private void connect0(InetAddress address,
                      int port)
               throws SocketException

Throws:

SocketException

disconnect0

private void disconnect0()

init

private static void init()

Perform class load-time initializations.