001    /* DatagramSocketImpl.java -- Abstract class for UDP socket implementations
002       Copyright (C) 1998, 1999 2000, 2001,
003                     2002, 2003 Free Software Foundation, Inc.
004    
005    This file is part of GNU Classpath.
006    
007    GNU Classpath is free software; you can redistribute it and/or modify
008    it under the terms of the GNU General Public License as published by
009    the Free Software Foundation; either version 2, or (at your option)
010    any later version.
011    
012    GNU Classpath is distributed in the hope that it will be useful, but
013    WITHOUT ANY WARRANTY; without even the implied warranty of
014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015    General Public License for more details.
016    
017    You should have received a copy of the GNU General Public License
018    along with GNU Classpath; see the file COPYING.  If not, write to the
019    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020    02110-1301 USA.
021    
022    Linking this library statically or dynamically with other modules is
023    making a combined work based on this library.  Thus, the terms and
024    conditions of the GNU General Public License cover the whole
025    combination.
026    
027    As a special exception, the copyright holders of this library give you
028    permission to link this library with independent modules to produce an
029    executable, regardless of the license terms of these independent
030    modules, and to copy and distribute the resulting executable under
031    terms of your choice, provided that you also meet, for each linked
032    independent module, the terms and conditions of the license of that
033    module.  An independent module is a module which is not derived from
034    or based on this library.  If you modify this library, you may extend
035    this exception to your version of the library, but you are not
036    obligated to do so.  If you do not wish to do so, delete this
037    exception statement from your version. */
038    
039    package java.net;
040    
041    import java.io.FileDescriptor;
042    import java.io.IOException;
043    
044    
045    /**
046     * This abstract class models a datagram socket implementation.  An
047     * actual implementation class would implement these methods, probably
048     * via redirecting them to native code.
049     * <p>
050     * Written using on-line Java Platform 1.2 API Specification, as well
051     * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
052     * <p>
053     * Status:  Believed complete and correct.
054     *
055     * @author Aaron M. Renn (arenn@urbanophile.com)
056     * @author Warren Levy (warrenl@cygnus.com)
057     * @since 1.1
058     */
059    public abstract class DatagramSocketImpl implements SocketOptions
060    {
061      /**
062       * The local port to which this socket is bound
063       */
064      protected int localPort;
065    
066      /**
067       * The FileDescriptor object for this object.
068       */
069      protected FileDescriptor fd;
070    
071      /**
072       * Default, no-argument constructor for subclasses to call.
073       */
074      public DatagramSocketImpl()
075      {
076      }
077    
078      /**
079       * This method binds the socket to the specified local port and address.
080       *
081       * @param lport The port number to bind to
082       * @param laddr The address to bind to
083       *
084       * @exception SocketException If an error occurs
085       */
086      protected abstract void bind(int lport, InetAddress laddr)
087        throws SocketException;
088    
089      /**
090       * This methods closes the socket
091       */
092      protected abstract void close();
093    
094      /**
095       * Creates a new datagram socket.
096       *
097       * @exception SocketException If an error occurs
098       */
099      protected abstract void create() throws SocketException;
100    
101      /**
102       * Takes a peek at the next packet received in order to retrieve the
103       * address of the sender
104       *
105       * @param i The <code>InetAddress</code> to fill in with the information
106       *          about the sender if the next packet
107       *
108       * @return The port number of the sender of the packet
109       *
110       * @exception IOException If an error occurs
111       * @exception PortUnreachableException May be thrown if the socket is
112       * connected to a currently unreachable destination. Note, there is no
113       * guarantee that the exception will be thrown.
114       */
115      protected abstract int peek(InetAddress i) throws IOException;
116    
117      /**
118       * Takes a peek at the next packet received.  This packet is not consumed.
119       * With the next peekData/receive operation this packet will be read again.
120       *
121       * @param p The <code>DatagramPacket</code> to fill in with the data sent.
122       *
123       * @return The port number of the sender of the packet.
124       *
125       * @exception IOException If an error occurs
126       * @exception PortUnreachableException May be thrown if the socket is
127       * connected to a currently unreachable destination. Note, there is no
128       * guarantee that the exception will be thrown.
129       *
130       * @since 1.4
131       */
132      protected abstract int peekData(DatagramPacket p) throws IOException;
133    
134      /**
135       * Transmits the specified packet of data to the network.  The destination
136       * host and port should be encoded in the packet.
137       *
138       * @param p The packet to send
139       *
140       * @exception IOException If an error occurs
141       * @exception PortUnreachableException May be thrown if the socket is
142       * connected to a currently unreachable destination. Note, there is no
143       * guarantee that the exception will be thrown.
144       */
145      protected abstract void send(DatagramPacket p) throws IOException;
146    
147      /**
148       * Receives a packet of data from the network  Will block until a packet
149       * arrives.  The packet info in populated into the passed in
150       * <code>DatagramPacket</code> object.
151       *
152       * @param p A place to store the incoming packet.
153       *
154       * @exception IOException If an error occurs
155       * @exception PortUnreachableException May be thrown if the socket is
156       * connected to a currently unreachable destination. Note, there is no
157       * guarantee that the exception will be thrown.
158       */
159      protected abstract void receive(DatagramPacket p) throws IOException;
160    
161      /**
162       * Connects the socket to a host specified by address and port.
163       *
164       * @param address The <code>InetAddress</code> of the host to connect to
165       * @param port The port number of the host to connect to
166       *
167       * @exception SocketException If an error occurs
168       *
169       * @since 1.4
170       */
171      protected void connect(InetAddress address, int port)
172        throws SocketException
173      {
174        // This method has to be overwritten by real implementations
175      }
176    
177      /**
178       * Disconnects the socket.
179       *
180       * @since 1.4
181       */
182      protected void disconnect()
183      {
184        // This method has to be overwritten by real implementations
185      }
186    
187      /**
188       * Sets the Time to Live (TTL) setting on this socket to the specified
189       * value. <b>Use <code>setTimeToLive(int)</code></b> instead.
190       *
191       * @param ttl The new Time to Live value
192       *
193       * @exception IOException If an error occurs
194       * @deprecated
195       */
196      protected abstract void setTTL(byte ttl) throws IOException;
197    
198      /**
199       * This method returns the current Time to Live (TTL) setting on this
200       * socket.  <b>Use <code>getTimeToLive()</code></b> instead.
201       *
202       * @return the current time-to-live
203       *
204       * @exception IOException If an error occurs
205       *
206       * @deprecated // FIXME: when ?
207       */
208      protected abstract byte getTTL() throws IOException;
209    
210      /**
211       * Sets the Time to Live (TTL) setting on this socket to the specified
212       * value.
213       *
214       * @param ttl The new Time to Live value
215       *
216       * @exception IOException If an error occurs
217       */
218      protected abstract void setTimeToLive(int ttl) throws IOException;
219    
220      /**
221       * This method returns the current Time to Live (TTL) setting on this
222       * socket.
223       *
224       * @return the current time-to-live
225       *
226       * @exception IOException If an error occurs
227       */
228      protected abstract int getTimeToLive() throws IOException;
229    
230      /**
231       * Causes this socket to join the specified multicast group
232       *
233       * @param inetaddr The multicast address to join with
234       *
235       * @exception IOException If an error occurs
236       */
237      protected abstract void join(InetAddress inetaddr) throws IOException;
238    
239      /**
240       * Causes the socket to leave the specified multicast group.
241       *
242       * @param inetaddr The multicast address to leave
243       *
244       * @exception IOException If an error occurs
245       */
246      protected abstract void leave(InetAddress inetaddr) throws IOException;
247    
248      /**
249       * Causes this socket to join the specified multicast group on a specified
250       * device
251       *
252       * @param mcastaddr The address to leave
253       * @param netIf The specified network interface to join the group at
254       *
255       * @exception IOException If an error occurs
256       *
257       * @since 1.4
258       */
259      protected abstract void joinGroup(SocketAddress mcastaddr,
260                                        NetworkInterface netIf)
261        throws IOException;
262    
263      /**
264       * Leaves a multicast group
265       *
266       * @param mcastaddr The address to join
267       * @param netIf The specified network interface to leave the group at
268       *
269       * @exception IOException If an error occurs
270       *
271       * @since 1.4
272       */
273      protected abstract void leaveGroup(SocketAddress mcastaddr,
274                                         NetworkInterface netIf)
275        throws IOException;
276    
277      /**
278       * Returns the FileDescriptor for this socket
279       *
280       * @return the file descriptor associated with this socket
281       */
282      protected FileDescriptor getFileDescriptor()
283      {
284        return fd;
285      }
286    
287      /**
288       * Returns the local port this socket is bound to
289       *
290       * @return the local port
291       */
292      protected int getLocalPort()
293      {
294        return localPort;
295      }
296    }