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 * Copyright (c) 2009, 2017, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package com.sun.nio.sctp;

import java.net.SocketAddress;
import java.net.InetAddress;
import java.io.IOException;
import java.util.Set;
import java.nio.channels.SelectionKey;
import java.nio.channels.spi.SelectorProvider;
import java.nio.channels.spi.AbstractSelectableChannel;

/**
 * A selectable channel for message-oriented listening SCTP sockets.
 *
 * <p> An {@code SCTPServerChannel} is created by invoking the
 * {@link #open open} method of this class. A newly-created SCTP server
 * channel is open but not yet bound. An attempt to invoke the
 * {@link #accept accept} method of an unbound channel will cause the
 * {@link java.nio.channels.NotYetBoundException} to be thrown. An SCTP server
 * channel can be bound by invoking one of the
 * {@link #bind(java.net.SocketAddress,int) bind} methods defined by this class.
 *
 * <p> Socket options are configured using the
 * {@link #setOption(SctpSocketOption,Object) setOption} method. SCTP server socket
 * channels support the following options:
 * <blockquote>
 * <table class="striped">
 *   <caption style="display:none">Socket options</caption>
 *   <thead>
 *   <tr>
 *     <th scope="col">Option Name</th>
 *     <th scope="col">Description</th>
 *   </tr>
 *   </thead>
 *   <tbody>
 *   <tr>
 *     <th scope="row"> {@link SctpStandardSocketOptions#SCTP_INIT_MAXSTREAMS
 *                                          SCTP_INIT_MAXSTREAMS} </th>
 *     <td> The maximum number of streams requested by the local endpoint during
 *          association initialization </td>
 *   </tr>
 *   </tbody>
 * </table>
 * </blockquote>
 * Additional (implementation specific) options may also be supported. The list
 * of options supported is obtained by invoking the {@link #supportedOptions()
 * supportedOptions} method.
 *
 * <p>SCTP server channels are safe for use by multiple concurrent threads.
 *
 * @since 1.7
 */
public abstract class SctpServerChannel
    extends AbstractSelectableChannel
{
    /**
     * Initializes a new instance of this class.
     *
     * @param  provider
     *         The selector provider for this channel
     */
    protected SctpServerChannel(SelectorProvider provider) {
        super(provider);
    }

    /**
     * Opens an SCTP server channel.
     *
     * <P> The new channel's socket is initially unbound; it must be bound
     * to a specific address via one of its socket's {@link #bind bind}
     * methods before associations can be accepted.
     *
     * @return  A new SCTP server channel
     *
     * @throws  UnsupportedOperationException
     *          If the SCTP protocol is not supported
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    public static SctpServerChannel open() throws
        IOException {
        return new sun.nio.ch.sctp.SctpServerChannelImpl((SelectorProvider)null);
    }

    /**
     * Accepts an association on this channel's socket.
     *
     * <P> If this channel is in non-blocking mode then this method will
     * immediately return {@code null} if there are no pending associations.
     * Otherwise it will block indefinitely until a new association is
     * available or an I/O error occurs.
     *
     * <P> The {@code SCTPChannel} returned by this method, if any, will be in
     *  blocking mode regardless of the blocking mode of this channel.
     *
     * <P> If a security manager has been installed then for each new
     * association this method verifies that the address and port number of the
     * assocaitions's remote peer are permitted by the security manager's {@link
     * java.lang.SecurityManager#checkAccept(String,int) checkAccept} method.
     *
     * @return  The SCTP channel for the new association, or {@code null}
     *          if this channel is in non-blocking mode and no association is
     *          available to be accepted
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  java.nio.channels.AsynchronousCloseException
     *          If another thread closes this channel
     *          while the accept operation is in progress
     *
     * @throws  java.nio.channels.ClosedByInterruptException
     *          If another thread interrupts the current thread
     *          while the accept operation is in progress, thereby
     *          closing the channel and setting the current thread's
     *          interrupt status
     *
     * @throws  java.nio.channels.NotYetBoundException
     *          If this channel's socket has not yet been bound
     *
     * @throws  SecurityException
     *          If a security manager has been installed and it does not permit
     *          access to the remote peer of the new association
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract SctpChannel accept() throws IOException;

    /**
     * Binds the channel's socket to a local address and configures the socket
     * to listen for associations.
     *
     * <P> This method works as if invoking it were equivalent to evaluating the
     * expression:
     * <blockquote><pre>
     * bind(local, 0);
     * </pre></blockquote>
     *
     * @param  local
     *         The local address to bind the socket, or {@code null} to
     *         bind the socket to an automatically assigned socket address
     *
     * @return  This channel
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  java.nio.channels.AlreadyBoundException
     *          If this channel is already bound
     *
     * @throws  java.nio.channels.UnsupportedAddressTypeException
     *          If the type of the given address is not supported
     *
     * @throws  SecurityException
     *          If a security manager has been installed and its {@link
     *          java.lang.SecurityManager#checkListen(int) checkListen} method
     *          denies the operation
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public final SctpServerChannel bind(SocketAddress local)
        throws IOException {
        return bind(local, 0);
    }

    /**
     * Binds the channel's socket to a local address and configures the socket
     * to listen for associations.
     *
     * <P> This method is used to establish a relationship between the socket
     * and the local address. Once a relationship is established then
     * the socket remains bound until the channel is closed. This relationship
     * may not necesssarily be with the address {@code local} as it may be
     * removed by {@link #unbindAddress unbindAddress}, but there will always be
     * at least one local address bound to the channel's socket once an
     * invocation of this method successfully completes.
     *
     * <P> Once the channel's socket has been successfully bound to a specific
     * address, that is not automatically assigned, more addresses
     * may be bound to it using {@link #bindAddress bindAddress}, or removed
     * using {@link #unbindAddress unbindAddress}.
     *
     * <P> The backlog parameter is the maximum number of pending associations
     * on the socket. Its exact semantics are implementation specific. An
     * implementation may impose an implementation specific maximum length or
     * may choose to ignore the parameter. If the backlog parameter has the
     * value {@code 0}, or a negative value, then an implementation specific
     * default is used.
     *
     * @param  local
     *         The local address to bind the socket, or {@code null} to
     *         bind the socket to an automatically assigned socket address
     *
     * @param  backlog
     *         The maximum number of pending associations
     *
     * @return  This channel
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  java.nio.channels.AlreadyBoundException
     *          If this channel is already bound
     *
     * @throws  java.nio.channels.UnsupportedAddressTypeException
     *          If the type of the given address is not supported
     *
     * @throws  SecurityException
     *          If a security manager has been installed and its {@link
     *          java.lang.SecurityManager#checkListen(int) checkListen} method
     *          denies the operation
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract SctpServerChannel bind(SocketAddress local,
                                           int backlog)
        throws IOException;

    /**
     * Adds the given address to the bound addresses for the channel's
     * socket.
     *
     * <P> The given address must not be the {@link
     * java.net.InetAddress#isAnyLocalAddress wildcard} address.
     * The channel must be first bound using {@link #bind bind} before
     * invoking this method, otherwise {@link
     * java.nio.channels.NotYetBoundException} is thrown. The {@link #bind bind}
     * method takes a {@code SocketAddress} as its argument which typically
     * contains a port number as well as an address. Addresses subquently bound
     * using this method are simply addresses as the SCTP port number remains
     * the same for the lifetime of the channel.
     *
     * <P> New associations accepted after this method successfully completes
     * will be associated with the given address.
     *
     * @param  address
     *         The address to add to the bound addresses for the socket
     *
     * @return  This channel
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  java.nio.channels.NotYetBoundException
     *          If this channel is not yet bound
     *
     * @throws  java.nio.channels.AlreadyBoundException
     *          If this channel is already bound to the given address
     *
     * @throws  IllegalArgumentException
     *          If address is {@code null} or the {@link
     *          java.net.InetAddress#isAnyLocalAddress wildcard} address
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract SctpServerChannel bindAddress(InetAddress address)
         throws IOException;

    /**
     * Removes the given address from the bound addresses for the channel's
     * socket.
     *
     * <P> The given address must not be the {@link
     * java.net.InetAddress#isAnyLocalAddress wildcard} address.
     * The channel must be first bound using {@link #bind bind} before
     * invoking this method, otherwise
     * {@link java.nio.channels.NotYetBoundException} is thrown.
     * If this method is invoked on a channel that does not have
     * {@code address} as one of its bound addresses, or that has only one
     * local address bound to it, then this method throws {@link
     * IllegalUnbindException}.
     * The initial address that the channel's socket is bound to using
     * {@link #bind bind} may be removed from the bound addresses for the
     * channel's socket.
     *
     * <P> New associations accepted after this method successfully completes
     * will not be associated with the given address.
     *
     * @param  address
     *         The address to remove from the bound addresses for the socket
     *
     * @return  This channel
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  java.nio.channels.NotYetBoundException
     *          If this channel is not yet bound
     *
     * @throws  IllegalArgumentException
     *          If address is {@code null} or the {@link
     *          java.net.InetAddress#isAnyLocalAddress wildcard} address
     *
     * @throws  IllegalUnbindException
     *          If the implementation does not support removing addresses from a
     *          listening socket, {@code address} is not bound to the channel's
     *          socket, or the channel has only one address bound to it
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract SctpServerChannel unbindAddress(InetAddress address)
         throws IOException;

    /**
     * Returns all of the socket addresses to which this channel's socket is
     * bound.
     *
     * @return  All the socket addresses that this channel's socket is
     *          bound to, or an empty {@code Set} if the channel's socket is not
     *          bound
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If the channel is closed
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    public abstract Set<SocketAddress> getAllLocalAddresses()
        throws IOException;

    /**
     * Returns the value of a socket option.
     *
     * @param   <T>
     *          The type of the socket option value
     *
     * @param   name
     *          The socket option
     *
     * @return  The value of the socket option. A value of {@code null} may be
     *          a valid value for some socket options.
     *
     * @throws  UnsupportedOperationException
     *          If the socket option is not supported by this channel
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  IOException
     *          If an I/O error occurs
     *
     * @see SctpStandardSocketOptions
     */
    public abstract <T> T getOption(SctpSocketOption<T> name) throws IOException;

    /**
     * Sets the value of 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
     *          a valid value for some socket options.
     *
     * @return  This channel
     *
     * @throws  UnsupportedOperationException
     *          If the socket option is not supported by this channel
     *
     * @throws  IllegalArgumentException
     *          If the value is not a valid value for this socket option
     *
     * @throws  java.nio.channels.ClosedChannelException
     *          If this channel is closed
     *
     * @throws  IOException
     *          If an I/O error occurs
     *
     * @see SctpStandardSocketOptions
     */
    public abstract <T> SctpServerChannel setOption(SctpSocketOption<T> name,
                                                    T value)
        throws IOException;

    /**
     * Returns a set of the socket options supported by this channel.
     *
     * <P> This method will continue to return the set of options even after the
     * channel has been closed.
     *
     * @return  A set of the socket options supported by this channel
     */
    public abstract Set<SctpSocketOption<?>> supportedOptions();

    /**
     * Returns an operation set identifying this channel's supported
     * operations.
     *
     * <P> SCTP server channels only support the accepting of new
     * associations, so this method returns
     * {@link java.nio.channels.SelectionKey#OP_ACCEPT}.
     *
     * @return  The valid-operation set
     */
    @Override
    public final int validOps() {
        return SelectionKey.OP_ACCEPT;
    }
}
