libjava/java/net/SocketImpl.java

   1 /* SocketImpl.java -- Abstract socket implementation class
   2    Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package java.net;
  39
  40 import java.io.*;
  41
  42 /* Written using on-line Java Platform 1.2 API Specification.
  43  * Believed complete and correct.
  44  */
  45
  46 /**
  47  * This abstract class serves as the parent class for socket implementations.
  48  * The implementation class serves an intermediary to native routines that
  49  * perform system specific socket operations.
  50  * <p>
  51  * A default implementation is provided by the system, but this can be
  52  * changed via installing a <code>SocketImplFactory</code> (through a call
  53  * to the static method <code>Socket.setSocketImplFactory</code>).  A
  54  * subclass of <code>Socket</code> can also pass in a <code>SocketImpl</code>
  55  * to the <code>Socket(SocketImpl)</code> constructor to use an
  56  * implementation different from the system default without installing
  57  * a factory.
  58  *
  59  * @author Aaron M. Renn (arenn@urbanophile.com)
  60  * @author Per Bothner <bothner@cygnus.com>
  61  */
  62 public abstract class SocketImpl implements SocketOptions
  63 {
  64   /**
  65    * The address of the remote end of the socket connection
  66    */
  67   protected InetAddress address;
  68
  69   /**
  70    * A FileDescriptor object representing this socket connection.
  71    */
  72   protected FileDescriptor fd;
  73
  74   /**
  75    * The port number the socket is bound to locally
  76    */
  77   protected int localport = -1;
  78
  79   /**
  80    * The port number of the remote end of the socket connection
  81    */
  82   protected int port;
  83
  84   /**
  85    * Default, no-argument constructor for use by subclasses.
  86    */
  87   public SocketImpl()
  88   {
  89   }
  90
  91   /**
  92    * Creates a new socket that is not bound to any local address/port and
  93    * is not connected to any remote address/port.  This will be created as
  94    * a stream socket if the stream parameter is true, or a datagram socket
  95    * if the stream parameter is false.
  96    *
  97    * @param stream true for a stream socket, false for a datagram socket
  98    *
  99    * @exception IOException If an error occurs
 100    */
 101   protected abstract void create(boolean stream) throws IOException;
 102
 103   /**
 104    * Connects to the remote hostname and port specified as arguments.
 105    *
 106    * @param host The remote hostname to connect to
 107    * @param port The remote port to connect to
 108    *
 109    * @exception IOException If an error occurs
 110    */
 111   protected abstract void connect(String host, int port) throws IOException;
 112
 113   /**
 114    * Connects to the remote address and port specified as arguments.
 115    *
 116    * @param host The remote address to connect to
 117    * @param port The remote port to connect to
 118    *
 119    * @exception IOException If an error occurs
 120    */
 121   protected abstract void connect(InetAddress host, int port)
 122     throws IOException;
 123
 124   /**
 125    * Connects to the socket to the host specified in address. This
 126    * method blocks until successful connected or the timeout occurs.
 127    * A timeout of zero means no timout.
 128    *
 129    * @param address Data of remote host
 130    * @param timeout time to wait to stop connecting
 131    *
 132    * @exception IOException If an error occurs
 133    *
 134    * @since 1.4
 135    */
 136   protected abstract void connect(SocketAddress address, int timeout)
 137     throws IOException;
 138
 139   /**
 140    * Binds to the specified port on the specified addr.  Note that this addr
 141    * must represent a local IP address.
 142    * <p>
 143    * Note that it is unspecified how to bind to all interfaces on the localhost
 144    * (INADDR_ANY).
 145    *
 146    * @param host The address to bind to
 147    * @param port The port number to bind to
 148    *
 149    * @exception IOException If an error occurs
 150    */
 151   protected abstract void bind(InetAddress host, int port) throws IOException;
 152
 153   /**
 154    * Starts listening for connections on a socket. The backlog parameter
 155    * is how many pending connections will queue up waiting to be serviced
 156    * before being accept'ed.  If the queue of pending requests exceeds this
 157    * number, additional connections will be refused.
 158    *
 159    * @param backlog The length of the pending connection queue
 160    *
 161    * @exception IOException If an error occurs
 162    */
 163   protected abstract void listen(int backlog) throws IOException;
 164
 165   /**
 166    * Accepts a connection on this socket.
 167    *
 168    * @param s The implementation object for the accepted connection.
 169    *
 170    * @exception IOException If an error occurs
 171    */
 172   protected abstract void accept(SocketImpl s) throws IOException;
 173
 174   /**
 175    * Returns an <code>InputStream</code> object for reading from this socket.
 176    *
 177    * @return An <code>InputStream</code> for reading from this socket.
 178    *
 179    * @exception IOException If an error occurs
 180    */
 181   protected abstract InputStream getInputStream() throws IOException;
 182
 183   /**
 184    * Returns an <code>OutputStream</code> object for writing to this socket
 185    *
 186    * @return An <code>OutputStream</code> for writing to this socket.
 187    *
 188    * @exception IOException If an error occurs.
 189    */
 190   protected abstract OutputStream getOutputStream() throws IOException;
 191
 192   /**
 193    * Returns the number of bytes that the caller can read from this socket
 194    * without blocking.
 195    *
 196    * @return The number of readable bytes before blocking
 197    *
 198    * @exception IOException If an error occurs
 199    */
 200   protected abstract int available() throws IOException;
 201
 202   /**
 203    * Closes the socket.  This will normally cause any resources, such as the
 204    * InputStream, OutputStream and associated file descriptors  to be freed.
 205    * <p>
 206    * Note that if the SO_LINGER option is set on this socket, then the
 207    * operation could block.
 208    *
 209    * @exception IOException If an error occurs
 210    */
 211   protected abstract void close() throws IOException;
 212
 213   /**
 214    * Returns the FileDescriptor objects for this socket.
 215    *
 216    * @return A FileDescriptor for this socket.
 217    */
 218   protected FileDescriptor getFileDescriptor() { return fd; }
 219
 220   /**
 221    * Returns the remote address this socket is connected to
 222    *
 223    * @return The remote address
 224    */
 225   protected InetAddress getInetAddress() { return address; }
 226
 227   /**
 228    * Returns the remote port this socket is connected to
 229    *
 230    * @return The remote port
 231    */
 232   protected int getPort() { return port; }
 233
 234   /**
 235    * Returns true or false when this socket supports sending urgent data
 236    * or not.
 237    *
 238    * @since 1.4
 239    */
 240   protected boolean supportsUrgentData()
 241   {
 242     // This method has to be overwritten by socket classes that support
 243     // sending urgend data.
 244     return false;
 245   }
 246
 247   /**
 248    * Sends one byte of urgent data to the socket.
 249    *
 250    * @param data The byte to send, the low eight bits of it
 251    *
 252    * @exception IOException If an error occurs
 253    *
 254    * @since 1.4
 255    */
 256   protected abstract void sendUrgentData(int data)
 257     throws IOException;
 258
 259   /**
 260    * Returns the local port this socket is bound to
 261    *
 262    * @return The local port
 263    */
 264   protected int getLocalPort() { return localport; }
 265
 266   /**
 267    * Returns a <code>String</code> representing the remote host and port of
 268    * this socket.
 269    *
 270    * @return A <code>String</code> for this socket.
 271    */
 272   public String toString()
 273   {
 274     return "[addr=" + address
 275             + ",port=" + port
 276             + ",localport=" + localport + "]";
 277   }
 278
 279   /**
 280    * Sets the specified option on a socket to the passed in object.  For
 281    * options that take an integer argument, the passed in object is an
 282    * <code>Integer</code>.  For options that are set to on or off, the
 283    * value passed will be a <code>Boolean</code>.   The <code>option_id</code>
 284    * parameter is one of the defined constants in the superinterface.
 285    *
 286    * @param option_id The identifier of the option
 287    * @param val The value to set the option to
 288    *
 289    * @exception SocketException If an error occurs
 290    * @XXX This redeclaration from SocketOptions is a workaround to a gcj bug.
 291    */
 292   public abstract void setOption(int option_id, Object val)
 293     throws SocketException;
 294
 295   /**
 296    * Returns the current setting of the specified option.  The
 297    * <code>Object</code> returned will be an <code>Integer</code> for options
 298    * that have integer values.  For options that are set to on or off, a
 299    * <code>Boolean</code> will be returned.   The <code>option_id</code>
 300    * is one of the defined constants in the superinterface.
 301    *
 302    * @param option_id The option identifier
 303    *
 304    * @return The current value of the option
 305    *
 306    * @exception SocketException If an error occurs
 307    * @XXX This redeclaration from SocketOptions is a workaround to a gcj bug.
 308    */
 309   public abstract Object getOption(int option_id) throws SocketException;
 310
 311   /**
 312    * Shut down the input side of this socket.  Subsequent reads will
 313    * return end-of-file.
 314    *
 315    * @exception IOException if an error occurs
 316    */
 317   protected abstract void shutdownInput () throws IOException;
 318
 319   /**
 320    * Shut down the output side of this socket.  Subsequent writes will
 321    * fail with an IOException.
 322    *
 323    * @exception IOException if an error occurs
 324    */
 325   protected abstract void shutdownOutput () throws IOException;
 326 }