001    /* SocketImpl.java -- Abstract socket implementation class
002       Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
003       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    import java.io.InputStream;
044    import java.io.OutputStream;
045    
046    
047    /* Written using on-line Java Platform 1.2 API Specification.
048     * Believed complete and correct.
049     */
050    
051    /**
052     * This abstract class serves as the parent class for socket implementations.
053     * The implementation class serves an intermediary to native routines that
054     * perform system specific socket operations.
055     * <p>
056     * A default implementation is provided by the system, but this can be
057     * changed via installing a <code>SocketImplFactory</code> (through a call
058     * to the static method <code>Socket.setSocketImplFactory</code>).  A
059     * subclass of <code>Socket</code> can also pass in a <code>SocketImpl</code>
060     * to the <code>Socket(SocketImpl)</code> constructor to use an
061     * implementation different from the system default without installing
062     * a factory.
063     *
064     * @author Aaron M. Renn (arenn@urbanophile.com)
065     * @author Per Bothner (bothner@cygnus.com)
066     */
067    public abstract class SocketImpl implements SocketOptions
068    {
069      /**
070       * The address of the remote end of the socket connection
071       */
072      protected InetAddress address;
073    
074      /**
075       * A FileDescriptor object representing this socket connection.
076       */
077      protected FileDescriptor fd;
078    
079      /**
080       * The port number the socket is bound to locally
081       */
082      protected int localport = -1;
083    
084      /**
085       * The port number of the remote end of the socket connection
086       */
087      protected int port;
088    
089      /**
090       * Default, no-argument constructor for use by subclasses.
091       */
092      public SocketImpl()
093      {
094      }
095    
096      /**
097       * Creates a new socket that is not bound to any local address/port and
098       * is not connected to any remote address/port.  This will be created as
099       * a stream socket if the stream parameter is true, or a datagram socket
100       * if the stream parameter is false.
101       *
102       * @param stream true for a stream socket, false for a datagram socket
103       *
104       * @exception IOException If an error occurs
105       */
106      protected abstract void create(boolean stream) throws IOException;
107    
108      /**
109       * Connects to the remote hostname and port specified as arguments.
110       *
111       * @param host The remote hostname to connect to
112       * @param port The remote port to connect to
113       *
114       * @exception IOException If an error occurs
115       */
116      protected abstract void connect(String host, int port)
117        throws IOException;
118    
119      /**
120       * Connects to the remote address and port specified as arguments.
121       *
122       * @param host The remote address to connect to
123       * @param port The remote port to connect to
124       *
125       * @exception IOException If an error occurs
126       */
127      protected abstract void connect(InetAddress host, int port)
128        throws IOException;
129    
130      /**
131       * Connects to the socket to the host specified in address. This
132       * method blocks until successful connected or the timeout occurs.
133       * A timeout of zero means no timout.
134       *
135       * @param address Data of remote host
136       * @param timeout time to wait to stop connecting
137       *
138       * @exception IOException If an error occurs
139       *
140       * @since 1.4
141       */
142      protected abstract void connect(SocketAddress address, int timeout)
143        throws IOException;
144    
145      /**
146       * Binds to the specified port on the specified addr.  Note that this addr
147       * must represent a local IP address.
148       * <p>
149       * Note that it is unspecified how to bind to all interfaces on the localhost
150       * (INADDR_ANY).
151       *
152       * @param host The address to bind to
153       * @param port The port number to bind to
154       *
155       * @exception IOException If an error occurs
156       */
157      protected abstract void bind(InetAddress host, int port)
158        throws IOException;
159    
160      /**
161       * Starts listening for connections on a socket. The backlog parameter
162       * is how many pending connections will queue up waiting to be serviced
163       * before being accept'ed.  If the queue of pending requests exceeds this
164       * number, additional connections will be refused.
165       *
166       * @param backlog The length of the pending connection queue
167       *
168       * @exception IOException If an error occurs
169       */
170      protected abstract void listen(int backlog) throws IOException;
171    
172      /**
173       * Accepts a connection on this socket.
174       *
175       * @param s The implementation object for the accepted connection.
176       *
177       * @exception IOException If an error occurs
178       */
179      protected abstract void accept(SocketImpl s) throws IOException;
180    
181      /**
182       * Returns an <code>InputStream</code> object for reading from this socket.
183       *
184       * @return An <code>InputStream</code> for reading from this socket.
185       *
186       * @exception IOException If an error occurs
187       */
188      protected abstract InputStream getInputStream() throws IOException;
189    
190      /**
191       * Returns an <code>OutputStream</code> object for writing to this socket
192       *
193       * @return An <code>OutputStream</code> for writing to this socket.
194       *
195       * @exception IOException If an error occurs.
196       */
197      protected abstract OutputStream getOutputStream() throws IOException;
198    
199      /**
200       * Returns the number of bytes that the caller can read from this socket
201       * without blocking.
202       *
203       * @return The number of readable bytes before blocking
204       *
205       * @exception IOException If an error occurs
206       */
207      protected abstract int available() throws IOException;
208    
209      /**
210       * Closes the socket.  This will normally cause any resources, such as the
211       * InputStream, OutputStream and associated file descriptors  to be freed.
212       * <p>
213       * Note that if the SO_LINGER option is set on this socket, then the
214       * operation could block.
215       *
216       * @exception IOException If an error occurs
217       */
218      protected abstract void close() throws IOException;
219    
220      /**
221       * Returns the FileDescriptor objects for this socket.
222       *
223       * @return A FileDescriptor for this socket.
224       */
225      protected FileDescriptor getFileDescriptor()
226      {
227        return fd;
228      }
229    
230      /**
231       * Returns the remote address this socket is connected to
232       *
233       * @return The remote address
234       */
235      protected InetAddress getInetAddress()
236      {
237        return address;
238      }
239    
240      /**
241       * Returns the remote port this socket is connected to
242       *
243       * @return The remote port
244       */
245      protected int getPort()
246      {
247        return port;
248      }
249    
250      /**
251       * Returns true or false when this socket supports sending urgent data
252       * or not.
253       *
254       * @return true if the socket implementation supports sending urgent data,
255       * false otherwise
256       *
257       * @since 1.4
258       */
259      protected boolean supportsUrgentData()
260      {
261        // This method has to be overwritten by socket classes that support
262        // sending urgend data.
263        return false;
264      }
265    
266      /**
267       * Sends one byte of urgent data to the socket.
268       *
269       * @param data The byte to send, the low eight bits of it
270       *
271       * @exception IOException If an error occurs
272       *
273       * @since 1.4
274       */
275      protected abstract void sendUrgentData(int data) throws IOException;
276    
277      /**
278       * Returns the local port this socket is bound to
279       *
280       * @return The local port
281       */
282      protected int getLocalPort()
283      {
284        return localport;
285      }
286    
287      /**
288       * Returns a <code>String</code> representing the remote host and port of
289       * this socket.
290       *
291       * @return A <code>String</code> for this socket.
292       */
293      public String toString()
294      {
295        return "[addr="
296               + ((address == null) ? "0.0.0.0/0.0.0.0" : address.toString())
297               + ",port=" + port + ",localport=" + localport + "]";
298      }
299    
300      /**
301       * Shut down the input side of this socket.  Subsequent reads will
302       * return end-of-file.
303       *
304       * @exception IOException if an error occurs
305       */
306      protected void shutdownInput() throws IOException
307      {
308        throw new IOException("Not implemented in this socket class");
309      }
310    
311      /**
312       * Shut down the output side of this socket.  Subsequent writes will
313       * fail with an IOException.
314       *
315       * @exception IOException if an error occurs
316       */
317      protected void shutdownOutput() throws IOException
318      {
319        throw new IOException("Not implemented in this socket class");
320      }
321    }