/*

 * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.net;

import java.io.FileDescriptor;

import java.io.IOException;

import java.util.Set;

/**

 * Abstract datagram and multicast socket implementation base class.

 * @author Pavani Diwanji

 * @since  1.1

 */

public abstract class DatagramSocketImpl implements SocketOptions {

    /**

     * The local port number.

     */

    protected int localPort;

    /**

     * The file descriptor object.

     */

    protected FileDescriptor fd;

    /**

     * The DatagramSocket or MulticastSocket

     * that owns this impl

     */

    DatagramSocket socket;

    void setDatagramSocket(DatagramSocket socket) {

        this.socket = socket;

    }

    DatagramSocket getDatagramSocket() {

        return socket;

    }

    int dataAvailable() {

        // default impl returns zero, which disables the calling

        // functionality

        return 0;

    }

    /**

     * Creates a datagram socket.

     * @exception SocketException if there is an error in the

     * underlying protocol, such as a TCP error.

     */

    protected abstract void create() throws SocketException;

    /**

     * Binds a datagram socket to a local port and address.

     * @param lport the local port

     * @param laddr the local address

     * @exception SocketException if there is an error in the

     * underlying protocol, such as a TCP error.

     */

    protected abstract void bind(int lport, InetAddress laddr) throws SocketException;

    /**

     * Sends a datagram packet. The packet contains the data and the

     * destination address to send the packet to.

     * @param p the packet to be sent.

     * @exception IOException if an I/O exception occurs while sending the

     * datagram packet.

     * @exception  PortUnreachableException may be thrown if the socket is connected

     * to a currently unreachable destination. Note, there is no guarantee that

     * the exception will be thrown.

     */

    protected abstract void send(DatagramPacket p) throws IOException;

    /**

     * Connects a datagram socket to a remote destination. This associates the remote

     * address with the local socket so that datagrams may only be sent to this destination

     * and received from this destination. This may be overridden to call a native

     * system connect.

     *

     * <p>If the remote destination to which the socket is connected does not

     * exist, or is otherwise unreachable, and if an ICMP destination unreachable

     * packet has been received for that address, then a subsequent call to

     * send or receive may throw a PortUnreachableException.

     * Note, there is no guarantee that the exception will be thrown.

     * @param address the remote InetAddress to connect to

     * @param port the remote port number

     * @exception   SocketException may be thrown if the socket cannot be

     * connected to the remote destination

     * @since 1.4

     */

    protected void connect(InetAddress address, int port) throws SocketException {}

    /**

     * Disconnects a datagram socket from its remote destination.

     * @since 1.4

     */

    protected void disconnect() {}

    /**

     * Peek at the packet to see who it is from. Updates the specified {@code InetAddress}

     * to the address which the packet came from.

     * @param i an InetAddress object

     * @return the port number which the packet came from.

     * @exception IOException if an I/O exception occurs

     * @exception  PortUnreachableException may be thrown if the socket is connected

     *       to a currently unreachable destination. Note, there is no guarantee that the

     *       exception will be thrown.

     */

    protected abstract int peek(InetAddress i) throws IOException;

    /**

     * Peek at the packet to see who it is from. The data is copied into the specified

     * {@code DatagramPacket}. The data is returned,

     * but not consumed, so that a subsequent peekData/receive operation

     * will see the same data.

     * @param p the Packet Received.

     * @return the port number which the packet came from.

     * @exception IOException if an I/O exception occurs

     * @exception  PortUnreachableException may be thrown if the socket is connected

     *       to a currently unreachable destination. Note, there is no guarantee that the

     *       exception will be thrown.

     * @since 1.4

     */

    protected abstract int peekData(DatagramPacket p) throws IOException;

    /**

     * Receive the datagram packet.

     * @param p the Packet Received.

     * @exception IOException if an I/O exception occurs

     * while receiving the datagram packet.

     * @exception  PortUnreachableException may be thrown if the socket is connected

     *       to a currently unreachable destination. Note, there is no guarantee that the

     *       exception will be thrown.

     */

    protected abstract void receive(DatagramPacket p) throws IOException;

    /**

     * Set the TTL (time-to-live) option.

     * @param ttl a byte specifying the TTL value

     *

     * @deprecated use setTimeToLive instead.

     * @exception IOException if an I/O exception occurs while setting

     * the time-to-live option.

     * @see #getTTL()

     */

    @Deprecated

    protected abstract void setTTL(byte ttl) throws IOException;

    /**

     * Retrieve the TTL (time-to-live) option.

     *

     * @exception IOException if an I/O exception occurs

     * while retrieving the time-to-live option

     * @deprecated use getTimeToLive instead.

     * @return a byte representing the TTL value

     * @see #setTTL(byte)

     */

    @Deprecated

    protected abstract byte getTTL() throws IOException;

    /**

     * Set the TTL (time-to-live) option.

     * @param ttl an {@code int} specifying the time-to-live value

     * @exception IOException if an I/O exception occurs

     * while setting the time-to-live option.

     * @see #getTimeToLive()

     */

    protected abstract void setTimeToLive(int ttl) throws IOException;

    /**

     * Retrieve the TTL (time-to-live) option.

     * @exception IOException if an I/O exception occurs

     * while retrieving the time-to-live option

     * @return an {@code int} representing the time-to-live value

     * @see #setTimeToLive(int)

     */

    protected abstract int getTimeToLive() throws IOException;

    /**

     * Join the multicast group.

     * @param inetaddr multicast address to join.

     * @exception IOException if an I/O exception occurs

     * while joining the multicast group.

     */

    protected abstract void join(InetAddress inetaddr) throws IOException;

    /**

     * Leave the multicast group.

     * @param inetaddr multicast address to leave.

     * @exception IOException if an I/O exception occurs

     * while leaving the multicast group.

     */

    protected abstract void leave(InetAddress inetaddr) throws IOException;

    /**

     * Join the multicast group.

     * @param mcastaddr address to join.

     * @param netIf specifies the local interface to receive multicast

     *        datagram packets

     * @throws IOException if an I/O exception occurs while joining

     * the multicast group

     * @since 1.4

     */

    protected abstract void joinGroup(SocketAddress mcastaddr,

                                      NetworkInterface netIf)

        throws IOException;

    /**

     * Leave the multicast group.

     * @param mcastaddr address to leave.

     * @param netIf specified the local interface to leave the group at

     * @throws IOException if an I/O exception occurs while leaving

     * the multicast group

     * @since 1.4

     */

    protected abstract void leaveGroup(SocketAddress mcastaddr,

                                       NetworkInterface netIf)

        throws IOException;

    /**

     * Close the socket.

     */

    protected abstract void close();

    /**

     * Gets the local port.

     * @return an {@code int} representing the local port value

     */

    protected int getLocalPort() {

        return localPort;

    }

    /**

     * Gets the datagram socket file descriptor.

     * @return a {@code FileDescriptor} object representing the datagram socket

     * file descriptor

     */

    protected FileDescriptor getFileDescriptor() {

        return fd;

    }

    /**

     * Called to set a socket option.

     *

     * @param <T> The type of the socket option value

     * @param name The socket option

     *

     * @param value The value of the socket option. A value of {@code null}

     *              may be valid for some options.

     *

     * @throws UnsupportedOperationException if the DatagramSocketImpl does not

     *         support the option

     *

     * @throws NullPointerException if name is {@code null}

     * @throws IOException if an I/O problem occurs while attempting to set the option

     * @since 9

     */

    protected <T> void setOption(SocketOption<T> name, T value) throws IOException {

        if (name == StandardSocketOptions.SO_SNDBUF) {

            setOption(SocketOptions.SO_SNDBUF, value);

        } else if (name == StandardSocketOptions.SO_RCVBUF) {

            setOption(SocketOptions.SO_RCVBUF, value);

        } else if (name == StandardSocketOptions.SO_REUSEADDR) {

            setOption(SocketOptions.SO_REUSEADDR, value);

        } else if (name == StandardSocketOptions.SO_REUSEPORT &&

            supportedOptions().contains(name)) {

            setOption(SocketOptions.SO_REUSEPORT, value);

        } else if (name == StandardSocketOptions.IP_TOS) {

            setOption(SocketOptions.IP_TOS, value);

        } else if (name == StandardSocketOptions.IP_MULTICAST_IF &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            setOption(SocketOptions.IP_MULTICAST_IF2, value);

        } else if (name == StandardSocketOptions.IP_MULTICAST_TTL &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            if (! (value instanceof Integer)) {

                throw new IllegalArgumentException("not an integer");

            }

            setTimeToLive((Integer)value);

        } else if (name == StandardSocketOptions.IP_MULTICAST_LOOP &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            setOption(SocketOptions.IP_MULTICAST_LOOP, value);

        } else {

            throw new UnsupportedOperationException("unsupported option");

        }

    }

    /**

     * Called to get a socket option.

     *

     * @return the socket option

     * @param <T> The type of the socket option value

     * @param name The socket option

     *

     * @throws UnsupportedOperationException if the DatagramSocketImpl does not

     *         support the option

     *

     * @throws NullPointerException if name is {@code null}

     * @throws IOException if an I/O problem occurs while attempting to set the option

     *

     * @since 9

     */

    @SuppressWarnings("unchecked")

    protected <T> T getOption(SocketOption<T> name) throws IOException {

        if (name == StandardSocketOptions.SO_SNDBUF) {

            return (T) getOption(SocketOptions.SO_SNDBUF);

        } else if (name == StandardSocketOptions.SO_RCVBUF) {

            return (T) getOption(SocketOptions.SO_RCVBUF);

        } else if (name == StandardSocketOptions.SO_REUSEADDR) {

            return (T) getOption(SocketOptions.SO_REUSEADDR);

        } else if (name == StandardSocketOptions.SO_REUSEPORT &&

            supportedOptions().contains(name)) {

            return (T) getOption(SocketOptions.SO_REUSEPORT);

        } else if (name == StandardSocketOptions.IP_TOS) {

            return (T) getOption(SocketOptions.IP_TOS);

        } else if (name == StandardSocketOptions.IP_MULTICAST_IF &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            return (T) getOption(SocketOptions.IP_MULTICAST_IF2);

        } else if (name == StandardSocketOptions.IP_MULTICAST_TTL &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            Integer ttl = getTimeToLive();

            return (T)ttl;

        } else if (name == StandardSocketOptions.IP_MULTICAST_LOOP &&

            (getDatagramSocket() instanceof MulticastSocket)) {

            return (T) getOption(SocketOptions.IP_MULTICAST_LOOP);

        } else {

            throw new UnsupportedOperationException("unsupported option");

        }

    }

    private static final Set<SocketOption<?>> dgSocketOptions;

    private static final Set<SocketOption<?>> mcSocketOptions;

    static {

        dgSocketOptions = Set.of(StandardSocketOptions.SO_SNDBUF,

                                 StandardSocketOptions.SO_RCVBUF,

                                 StandardSocketOptions.SO_REUSEADDR,

                                 StandardSocketOptions.IP_TOS);

        mcSocketOptions = Set.of(StandardSocketOptions.SO_SNDBUF,

                                 StandardSocketOptions.SO_RCVBUF,

                                 StandardSocketOptions.SO_REUSEADDR,

                                 StandardSocketOptions.IP_TOS,

                                 StandardSocketOptions.IP_MULTICAST_IF,

                                 StandardSocketOptions.IP_MULTICAST_TTL,

                                 StandardSocketOptions.IP_MULTICAST_LOOP);

    }

    /**

     * Returns a set of SocketOptions supported by this impl

     * and by this impl's socket (DatagramSocket or MulticastSocket)

     *

     * @return a Set of SocketOptions

     *

     * @since 9

     */

    protected Set<SocketOption<?>> supportedOptions() {

        if (getDatagramSocket() instanceof MulticastSocket) {

            return mcSocketOptions;

        } else {

            return dgSocketOptions;

        }

    }

}