001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net;
019
020import java.net.DatagramSocket;
021import java.net.InetAddress;
022import java.net.SocketException;
023import java.nio.charset.Charset;
024import java.time.Duration;
025import java.util.Objects;
026
027import org.apache.commons.io.IOUtils;
028
029/**
030 * The DatagramSocketClient provides the basic operations that are required of client objects accessing datagram sockets. It is meant to be subclassed to avoid
031 * having to rewrite the same code over and over again to open a socket, close a socket, set timeouts, etc. Of special note is the
032 * {@link #setDatagramSocketFactory setDatagramSocketFactory)} method, which allows you to control the type of DatagramSocket the DatagramSocketClient creates
033 * for network communications. This is especially useful for adding things like proxy support as well as better support for applets. For example, you could
034 * create a {@link org.apache.commons.net.DatagramSocketFactory} that requests browser security capabilities before creating a socket. All classes derived from
035 * DatagramSocketClient should use the {@link #_socketFactory_ _socketFactory_} member variable to create DatagramSocket instances rather than instantiating
036 * them by directly invoking a constructor. By honoring this contract you guarantee that a user will always be able to provide his own Socket implementations by
037 * substituting his own SocketFactory.
038 *
039 * @see DatagramSocketFactory
040 */
041public abstract class DatagramSocketClient implements AutoCloseable {
042    /**
043     * The default DatagramSocketFactory shared by all DatagramSocketClient instances.
044     */
045    private static final DatagramSocketFactory DEFAULT_SOCKET_FACTORY = new DefaultDatagramSocketFactory();
046
047    /**
048     * Charset to use for byte IO.
049     */
050    private Charset charset = Charset.defaultCharset();
051
052    /** The timeout to use after opening a socket. */
053    protected int _timeout_;
054
055    /** The datagram socket used for the connection. */
056    protected DatagramSocket _socket_;
057
058    /**
059     * A status variable indicating if the client's socket is currently open.
060     */
061    protected boolean _isOpen_;
062
063    /** The datagram socket's DatagramSocketFactory. */
064    protected DatagramSocketFactory _socketFactory_ = DEFAULT_SOCKET_FACTORY;
065
066    /**
067     * Constructs a new instance. Initializes _socket_ to null, _timeout_ to 0, and _isOpen_ to false.
068     */
069    public DatagramSocketClient() {
070    }
071
072    /**
073     * Gets the non-null DatagramSocket or throws {@link NullPointerException}.
074     *
075     * <p>
076     * This method does not allocate resources.
077     * </p>
078     *
079     * @return the non-null DatagramSocket.
080     * @since 3.10.0
081     */
082    protected DatagramSocket checkOpen() {
083        return Objects.requireNonNull(_socket_, "DatagramSocket");
084    }
085
086    /**
087     * Closes the DatagramSocket used for the connection. You should call this method after you've finished using the class instance and also before you call
088     * {@link #open open()} again. _isOpen_ is set to false and _socket_ is set to null.
089     */
090    @Override
091    public void close() {
092        IOUtils.closeQuietly(_socket_); // DatagramSocket#close() doesn't throw in its signature.
093        _socket_ = null;
094        _isOpen_ = false;
095    }
096
097    /**
098     * Gets the charset.
099     *
100     * @return the charset.
101     * @since 3.3
102     */
103    public Charset getCharset() {
104        return charset;
105    }
106
107    /**
108     * Gets the charset name.
109     *
110     * @return the charset name.
111     * @since 3.3
112     * @deprecated Use {@link #getCharset()} instead
113     */
114    @Deprecated
115    public String getCharsetName() {
116        return charset.name();
117    }
118
119    /**
120     * Gets the default timeout in milliseconds that is used when opening a socket.
121     *
122     * @return The default timeout in milliseconds that is used when opening a socket.
123     */
124    public int getDefaultTimeout() {
125        return _timeout_;
126    }
127
128    /**
129     * Gets the local address to which the client's socket is bound. If you call this method when the client socket is not open, a NullPointerException is
130     * thrown.
131     *
132     * @return The local address to which the client's socket is bound.
133     */
134    public InetAddress getLocalAddress() {
135        return checkOpen().getLocalAddress();
136    }
137
138    /**
139     * Gets the port number of the open socket on the local host used for the connection. If you call this method when the client socket is not open, a
140     * NullPointerException is thrown.
141     *
142     * @return The port number of the open socket on the local host used for the connection.
143     */
144    public int getLocalPort() {
145        return checkOpen().getLocalPort();
146    }
147
148    /**
149     * Gets the timeout in milliseconds of the currently opened socket. If you call this method when the client socket is not open, a NullPointerException is
150     * thrown.
151     *
152     * @return The timeout in milliseconds of the currently opened socket.
153     * @throws SocketException if an error getting the timeout.
154     * @deprecated Use {@link #getSoTimeoutDuration()}.
155     */
156    @Deprecated
157    public int getSoTimeout() throws SocketException {
158        return checkOpen().getSoTimeout();
159    }
160
161    /**
162     * Gets the timeout duration of the currently opened socket. If you call this method when the client socket is not open, a NullPointerException is
163     * thrown.
164     *
165     * @return The timeout in milliseconds of the currently opened socket.
166     * @throws SocketException if an error getting the timeout.
167     */
168    public Duration getSoTimeoutDuration() throws SocketException {
169        return Duration.ofMillis(checkOpen().getSoTimeout());
170    }
171
172    /**
173     * Tests whether the client has a currently open socket.
174     *
175     * @return True if the client has a currently open socket, false otherwise.
176     */
177    public boolean isOpen() {
178        return _isOpen_;
179    }
180
181    /**
182     * Opens a DatagramSocket on the local host at the first available port. Also sets the timeout on the socket to the default timeout set by
183     * {@link #setDefaultTimeout setDefaultTimeout()}.
184     * <p>
185     * _isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.
186     * </p>
187     *
188     * @throws SocketException If the socket could not be opened or the timeout could not be set.
189     */
190    public void open() throws SocketException {
191        _socket_ = _socketFactory_.createDatagramSocket();
192        _socket_.setSoTimeout(_timeout_);
193        _isOpen_ = true;
194    }
195
196    /**
197     * Opens a DatagramSocket on the local host at a specified port. Also sets the timeout on the socket to the default timeout set by {@link #setDefaultTimeout
198     * setDefaultTimeout()}.
199     * <p>
200     * _isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.
201     * </p>
202     *
203     * @param port The port to use for the socket.
204     * @throws SocketException If the socket could not be opened or the timeout could not be set.
205     */
206    public void open(final int port) throws SocketException {
207        _socket_ = _socketFactory_.createDatagramSocket(port);
208        _socket_.setSoTimeout(_timeout_);
209        _isOpen_ = true;
210    }
211
212    /**
213     * Opens a DatagramSocket at the specified address on the local host at a specified port. Also sets the timeout on the socket to the default timeout set by
214     * {@link #setDefaultTimeout setDefaultTimeout()}.
215     * <p>
216     * _isOpen_ is set to true after calling this method and _socket_ is set to the newly opened socket.
217     * </p>
218     *
219     * @param port  The port to use for the socket.
220     * @param localAddress The local address to use.
221     * @throws SocketException If the socket could not be opened or the timeout could not be set.
222     */
223    public void open(final int port, final InetAddress localAddress) throws SocketException {
224        _socket_ = _socketFactory_.createDatagramSocket(port, localAddress);
225        _socket_.setSoTimeout(_timeout_);
226        _isOpen_ = true;
227    }
228
229    /**
230     * Sets the charset.
231     *
232     * @param charset the charset.
233     * @since 3.3
234     */
235    public void setCharset(final Charset charset) {
236        this.charset = charset;
237    }
238
239    /**
240     * Sets the DatagramSocketFactory used by the DatagramSocketClient to open DatagramSockets. If the factory value is null, then a default factory is used
241     * (only do this to reset the factory after having previously altered it).
242     *
243     * @param factory The new DatagramSocketFactory the DatagramSocketClient should use.
244     */
245    public void setDatagramSocketFactory(final DatagramSocketFactory factory) {
246        if (factory == null) {
247            _socketFactory_ = DEFAULT_SOCKET_FACTORY;
248        } else {
249            _socketFactory_ = factory;
250        }
251    }
252
253    /**
254     * Sets the default timeout in to use when opening a socket. After a call to open, the timeout for the socket is set using this value. This
255     * method should be used prior to a call to {@link #open open()} and should not be confused with {@link #setSoTimeout setSoTimeout()} which operates on the
256     * currently open socket. _timeout_ contains the new timeout value.
257     *
258     * @param timeout The timeout durations to use for the datagram socket connection.
259     */
260    public void setDefaultTimeout(final Duration timeout) {
261        _timeout_ = Math.toIntExact(timeout.toMillis());
262    }
263
264    /**
265     * Sets the default timeout in milliseconds to use when opening a socket. After a call to open, the timeout for the socket is set using this value. This
266     * method should be used prior to a call to {@link #open open()} and should not be confused with {@link #setSoTimeout setSoTimeout()} which operates on the
267     * currently open socket. _timeout_ contains the new timeout value.
268     *
269     * @param timeout The timeout in milliseconds to use for the datagram socket connection.
270     * @deprecated Use {@link #setDefaultTimeout(Duration)}.
271     */
272    @Deprecated
273    public void setDefaultTimeout(final int timeout) {
274        _timeout_ = timeout;
275    }
276
277    /**
278     * Sets the timeout duration of a currently open connection. Only call this method after a connection has been opened by {@link #open open()}.
279     *
280     * @param timeout The timeout in milliseconds to use for the currently open datagram socket connection.
281     * @throws SocketException if an error setting the timeout.
282     * @since 3.10.0
283     */
284    public void setSoTimeout(final Duration timeout) throws SocketException {
285        checkOpen().setSoTimeout(Math.toIntExact(timeout.toMillis()));
286    }
287
288    /**
289     * Sets the timeout in milliseconds of a currently open connection. Only call this method after a connection has been opened by {@link #open open()}.
290     *
291     * @param timeout The timeout in milliseconds to use for the currently open datagram socket connection.
292     * @throws SocketException if an error setting the timeout.
293     * @deprecated Use {@link #setSoTimeout(Duration)}.
294     */
295    @Deprecated
296    public void setSoTimeout(final int timeout) throws SocketException {
297        checkOpen().setSoTimeout(timeout);
298    }
299}