475 lines
17 KiB
Java
475 lines
17 KiB
Java
/*
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* Copyright (c) 1995, 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.net;
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import java.io.FileDescriptor;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.security.AccessController;
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import java.security.PrivilegedAction;
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import java.util.Objects;
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import java.util.Set;
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import sun.net.NetProperties;
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import sun.net.PlatformSocketImpl;
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import sun.nio.ch.NioSocketImpl;
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/**
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* The abstract class {@code SocketImpl} is a common superclass
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* of all classes that actually implement sockets. It is used to
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* create both client and server sockets.
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*
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* @implNote Client and server sockets created with the {@code Socket} and
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* {@code SocketServer} public constructors create a system-default
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* {@code SocketImpl}. The JDK historically used a {@code SocketImpl}
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* implementation type named "PlainSocketImpl" that has since been replaced by a
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* newer implementation. The JDK continues to ship with the older implementation
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* to allow code to run that depends on unspecified behavior that differs between
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* the old and new implementations. The old implementation will be used if the
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* Java virtual machine is started with the system property {@systemProperty
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* jdk.net.usePlainSocketImpl} set to use the old implementation. It may also be
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* set in the JDK's network configuration file, located in {@code
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* ${java.home}/conf/net.properties}. The value of the property is the string
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* representation of a boolean. If set without a value then it defaults to {@code
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* true}, hence running with {@code -Djdk.net.usePlainSocketImpl} or {@code
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* -Djdk.net.usePlainSocketImpl=true} will configure the Java virtual machine
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* to use the old implementation. The property and old implementation will be
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* removed in a future version.
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*
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* @since 1.0
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*/
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public abstract class SocketImpl implements SocketOptions {
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private static final boolean USE_PLAINSOCKETIMPL = usePlainSocketImpl();
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private static boolean usePlainSocketImpl() {
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PrivilegedAction<String> pa = () -> NetProperties.get("jdk.net.usePlainSocketImpl");
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String s = AccessController.doPrivileged(pa);
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return (s != null) && !s.equalsIgnoreCase("false");
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}
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/**
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* Creates an instance of platform's SocketImpl
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*/
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@SuppressWarnings("unchecked")
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static <S extends SocketImpl & PlatformSocketImpl> S createPlatformSocketImpl(boolean server) {
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if (USE_PLAINSOCKETIMPL) {
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return (S) new PlainSocketImpl(server);
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} else {
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return (S) new NioSocketImpl(server);
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}
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}
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/**
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* The file descriptor object for this socket.
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*/
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protected FileDescriptor fd;
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/**
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* The IP address of the remote end of this socket.
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*/
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protected InetAddress address;
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/**
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* The port number on the remote host to which this socket is connected.
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*/
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protected int port;
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/**
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* The local port number to which this socket is connected.
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*/
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protected int localport;
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/**
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* Initialize a new instance of this class
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*/
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public SocketImpl() { }
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/**
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* Creates either a stream or a datagram socket.
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*
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* @param stream if {@code true}, create a stream socket;
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* otherwise, create a datagram socket.
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* @throws IOException if an I/O error occurs while creating the
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* socket.
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*/
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protected abstract void create(boolean stream) throws IOException;
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/**
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* Connects this socket to the specified port on the named host.
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*
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* @param host the name of the remote host.
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* @param port the port number.
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* @throws IOException if an I/O error occurs when connecting to the
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* remote host.
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*/
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protected abstract void connect(String host, int port) throws IOException;
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/**
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* Connects this socket to the specified port number on the specified host.
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*
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* @param address the IP address of the remote host.
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* @param port the port number.
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* @throws IOException if an I/O error occurs when attempting a
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* connection.
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*/
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protected abstract void connect(InetAddress address, int port) throws IOException;
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/**
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* Connects this socket to the specified port number on the specified host.
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* A timeout of zero is interpreted as an infinite timeout. The connection
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* will then block until established or an error occurs.
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*
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* @param address the Socket address of the remote host.
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* @param timeout the timeout value, in milliseconds, or zero for no timeout.
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* @throws IOException if an I/O error occurs when attempting a
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* connection.
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* @since 1.4
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*/
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protected abstract void connect(SocketAddress address, int timeout) throws IOException;
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/**
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* Binds this socket to the specified local IP address and port number.
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*
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* @param host an IP address that belongs to a local interface.
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* @param port the port number.
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* @throws IOException if an I/O error occurs when binding this socket.
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*/
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protected abstract void bind(InetAddress host, int port) throws IOException;
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/**
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* Sets the maximum queue length for incoming connection indications
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* (a request to connect) to the {@code count} argument. If a
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* connection indication arrives when the queue is full, the
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* connection is refused.
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*
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* @param backlog the maximum length of the queue.
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* @throws IOException if an I/O error occurs when creating the queue.
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*/
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protected abstract void listen(int backlog) throws IOException;
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/**
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* Accepts a connection.
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*
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* @param s the accepted connection.
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* @throws IOException if an I/O error occurs when accepting the
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* connection.
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*/
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protected abstract void accept(SocketImpl s) throws IOException;
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/**
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* Returns an input stream for this socket.
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*
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* @return a stream for reading from this socket.
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* @throws IOException if an I/O error occurs when creating the
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* input stream.
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*/
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protected abstract InputStream getInputStream() throws IOException;
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/**
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* Returns an output stream for this socket.
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*
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* @return an output stream for writing to this socket.
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* @throws IOException if an I/O error occurs when creating the
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* output stream.
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*/
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protected abstract OutputStream getOutputStream() throws IOException;
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/**
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* Returns the number of bytes that can be read from this socket
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* without blocking.
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*
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* @return the number of bytes that can be read from this socket
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* without blocking.
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* @throws IOException if an I/O error occurs when determining the
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* number of bytes available.
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*/
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protected abstract int available() throws IOException;
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/**
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* Closes this socket.
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*
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* @throws IOException if an I/O error occurs when closing this socket.
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*/
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protected abstract void close() throws IOException;
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/**
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* Closes this socket, ignoring any IOException that is thrown by close.
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*/
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void closeQuietly() {
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try {
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close();
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} catch (IOException ignore) { }
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}
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/**
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* Places the input stream for this socket at "end of stream".
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* Any data sent to this socket is acknowledged and then
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* silently discarded.
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*
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* If you read from a socket input stream after invoking this method on the
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* socket, the stream's {@code available} method will return 0, and its
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* {@code read} methods will return {@code -1} (end of stream).
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*
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* @throws IOException if an I/O error occurs when shutting down this
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* socket.
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* @see java.net.Socket#shutdownOutput()
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* @see java.net.Socket#close()
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* @see java.net.Socket#setSoLinger(boolean, int)
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* @since 1.3
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*/
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protected void shutdownInput() throws IOException {
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throw new IOException("Method not implemented!");
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}
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/**
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* Disables the output stream for this socket.
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* For a TCP socket, any previously written data will be sent
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* followed by TCP's normal connection termination sequence.
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*
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* If you write to a socket output stream after invoking
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* shutdownOutput() on the socket, the stream will throw
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* an IOException.
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*
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* @throws IOException if an I/O error occurs when shutting down this
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* socket.
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* @see java.net.Socket#shutdownInput()
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* @see java.net.Socket#close()
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* @see java.net.Socket#setSoLinger(boolean, int)
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* @since 1.3
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*/
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protected void shutdownOutput() throws IOException {
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throw new IOException("Method not implemented!");
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}
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/**
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* Returns the value of this socket's {@code fd} field.
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*
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* @return the value of this socket's {@code fd} field.
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* @see java.net.SocketImpl#fd
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*/
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protected FileDescriptor getFileDescriptor() {
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return fd;
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}
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/**
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* Returns the value of this socket's {@code address} field.
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*
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* @return the value of this socket's {@code address} field.
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* @see java.net.SocketImpl#address
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*/
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protected InetAddress getInetAddress() {
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return address;
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}
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/**
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* Returns the value of this socket's {@code port} field.
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*
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* @return the value of this socket's {@code port} field.
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* @see java.net.SocketImpl#port
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*/
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protected int getPort() {
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return port;
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}
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/**
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* Returns whether or not this SocketImpl supports sending
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* urgent data. By default, false is returned
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* unless the method is overridden in a sub-class
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*
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* @return true if urgent data supported
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* @see java.net.SocketImpl#address
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* @since 1.4
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*/
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protected boolean supportsUrgentData () {
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return false; // must be overridden in sub-class
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}
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/**
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* Send one byte of urgent data on the socket.
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* The byte to be sent is the low eight bits of the parameter
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* @param data The byte of data to send
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* @throws IOException if there is an error
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* sending the data.
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* @since 1.4
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*/
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protected abstract void sendUrgentData (int data) throws IOException;
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/**
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* Returns the value of this socket's {@code localport} field.
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*
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* @return the value of this socket's {@code localport} field.
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* @see java.net.SocketImpl#localport
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*/
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protected int getLocalPort() {
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return localport;
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}
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/**
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* Returns the address and port of this socket as a {@code String}.
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*
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* @return a string representation of this socket.
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*/
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public String toString() {
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return "Socket[addr=" + getInetAddress() +
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",port=" + getPort() + ",localport=" + getLocalPort() + "]";
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}
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void reset() {
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fd = null;
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address = null;
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port = 0;
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localport = 0;
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}
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/**
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* Sets performance preferences for this socket.
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*
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* <p> Sockets use the TCP/IP protocol by default. Some implementations
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* may offer alternative protocols which have different performance
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* characteristics than TCP/IP. This method allows the application to
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* express its own preferences as to how these tradeoffs should be made
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* when the implementation chooses from the available protocols.
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*
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* <p> Performance preferences are described by three integers
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* whose values indicate the relative importance of short connection time,
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* low latency, and high bandwidth. The absolute values of the integers
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* are irrelevant; in order to choose a protocol the values are simply
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* compared, with larger values indicating stronger preferences. Negative
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* values represent a lower priority than positive values. If the
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* application prefers short connection time over both low latency and high
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* bandwidth, for example, then it could invoke this method with the values
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* {@code (1, 0, 0)}. If the application prefers high bandwidth above low
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* latency, and low latency above short connection time, then it could
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* invoke this method with the values {@code (0, 1, 2)}.
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*
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* By default, this method does nothing, unless it is overridden in
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* a sub-class.
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*
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* @param connectionTime
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* An {@code int} expressing the relative importance of a short
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* connection time
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*
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* @param latency
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* An {@code int} expressing the relative importance of low
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* latency
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*
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* @param bandwidth
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* An {@code int} expressing the relative importance of high
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* bandwidth
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*
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* @since 1.5
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*/
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protected void setPerformancePreferences(int connectionTime,
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int latency,
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int bandwidth)
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{
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/* Not implemented yet */
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}
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/**
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* Called to set a socket option.
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*
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* @implSpec
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* The default implementation of this method first checks that the given
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* socket option {@code name} is not null, then throws {@code
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* UnsupportedOperationException}. Subclasses should override this method
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* with an appropriate implementation.
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*
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* @param <T> The type of the socket option value
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* @param name The socket option
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* @param value The value of the socket option. A value of {@code null}
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* may be valid for some options.
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*
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* @throws UnsupportedOperationException if the SocketImpl does not
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* support the option
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* @throws IllegalArgumentException if the value is not valid for
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* the option
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* @throws IOException if an I/O error occurs, or if the socket is closed
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* @throws NullPointerException if name is {@code null}
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*
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* @since 9
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*/
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protected <T> void setOption(SocketOption<T> name, T value) throws IOException {
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Objects.requireNonNull(name);
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throw new UnsupportedOperationException("'" + name + "' not supported");
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}
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/**
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* Called to get a socket option.
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*
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* @implSpec
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* The default implementation of this method first checks that the given
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* socket option {@code name} is not null, then throws {@code
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* UnsupportedOperationException}. Subclasses should override this method
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* with an appropriate implementation.
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*
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* @param <T> The type of the socket option value
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* @param name The socket option
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* @return the value of the named option
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*
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* @throws UnsupportedOperationException if the SocketImpl does not
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* support the option
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* @throws IOException if an I/O error occurs, or if the socket is closed
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* @throws NullPointerException if name is {@code null}
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*
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* @since 9
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*/
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protected <T> T getOption(SocketOption<T> name) throws IOException {
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Objects.requireNonNull(name);
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throw new UnsupportedOperationException("'" + name + "' not supported");
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}
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/**
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* Attempts to copy socket options from this SocketImpl to a target SocketImpl.
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* At this time, only the SO_TIMEOUT make sense to copy.
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*/
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void copyOptionsTo(SocketImpl target) {
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try {
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Object timeout = getOption(SocketOptions.SO_TIMEOUT);
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if (timeout instanceof Integer) {
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target.setOption(SocketOptions.SO_TIMEOUT, timeout);
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}
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} catch (IOException ignore) { }
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}
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/**
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* Returns a set of SocketOptions supported by this impl
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* and by this impl's socket (Socket or ServerSocket)
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*
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* @implSpec
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* The default implementation of this method returns an empty set.
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* Subclasses should override this method with an appropriate implementation.
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*
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* @return a Set of SocketOptions
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*
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* @since 9
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*/
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protected Set<SocketOption<?>> supportedOptions() {
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return Set.of();
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}
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}
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