    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}