Java example source code file (DualStackPlainSocketImpl.java)

This example Java source code file (DualStackPlainSocketImpl.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractplainsocketimpl, dualstackplainsocketimpl, inetaddress, inetaddresscontainer, inetsocketaddress, ioexception, nullpointerexception, object, so_keepalive, so_oobinline, so_reuseaddr, socketexception, tcp_nodelay, wouldblock

The DualStackPlainSocketImpl.java Java example source code

/*
 * Copyright (c) 2007, 2013, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package java.net;

import java.io.IOException;
import java.io.FileDescriptor;
import sun.misc.SharedSecrets;
import sun.misc.JavaIOFileDescriptorAccess;

/**
 * This class defines the plain SocketImpl that is used on Windows platforms
 * greater or equal to Windows Vista. These platforms have a dual
 * layer TCP/IP stack and can handle both IPv4 and IPV6 through a
 * single file descriptor.
 *
 * @author Chris Hegarty
 */

class DualStackPlainSocketImpl extends AbstractPlainSocketImpl
{
    static JavaIOFileDescriptorAccess fdAccess = SharedSecrets.getJavaIOFileDescriptorAccess();


    // true if this socket is exclusively bound
    private final boolean exclusiveBind;

    // emulates SO_REUSEADDR when exclusiveBind is true
    private boolean isReuseAddress;

    public DualStackPlainSocketImpl(boolean exclBind) {
        exclusiveBind = exclBind;
    }

    public DualStackPlainSocketImpl(FileDescriptor fd, boolean exclBind) {
        this.fd = fd;
        exclusiveBind = exclBind;
    }

    void socketCreate(boolean stream) throws IOException {
        if (fd == null)
            throw new SocketException("Socket closed");

        int newfd = socket0(stream, false /*v6 Only*/);

        fdAccess.set(fd, newfd);
    }

    void socketConnect(InetAddress address, int port, int timeout)
        throws IOException {
        int nativefd = checkAndReturnNativeFD();

        if (address == null)
            throw new NullPointerException("inet address argument is null.");

        int connectResult;
        if (timeout <= 0) {
            connectResult = connect0(nativefd, address, port);
        } else {
            configureBlocking(nativefd, false);
            try {
                connectResult = connect0(nativefd, address, port);
                if (connectResult == WOULDBLOCK) {
                    waitForConnect(nativefd, timeout);
                }
            } finally {
                configureBlocking(nativefd, true);
            }
        }
        /*
         * We need to set the local port field. If bind was called
         * previous to the connect (by the client) then localport field
         * will already be set.
         */
        if (localport == 0)
            localport = localPort0(nativefd);
    }

    void socketBind(InetAddress address, int port) throws IOException {
        int nativefd = checkAndReturnNativeFD();

        if (address == null)
            throw new NullPointerException("inet address argument is null.");

        bind0(nativefd, address, port, exclusiveBind);
        if (port == 0) {
            localport = localPort0(nativefd);
        } else {
            localport = port;
        }

        this.address = address;
    }

    void socketListen(int backlog) throws IOException {
        int nativefd = checkAndReturnNativeFD();

        listen0(nativefd, backlog);
    }

    void socketAccept(SocketImpl s) throws IOException {
        int nativefd = checkAndReturnNativeFD();

        if (s == null)
            throw new NullPointerException("socket is null");

        int newfd = -1;
        InetSocketAddress[] isaa = new InetSocketAddress[1];
        if (timeout <= 0) {
            newfd = accept0(nativefd, isaa);
        } else {
            configureBlocking(nativefd, false);
            try {
                waitForNewConnection(nativefd, timeout);
                newfd = accept0(nativefd, isaa);
                if (newfd != -1) {
                    configureBlocking(newfd, true);
                }
            } finally {
                configureBlocking(nativefd, true);
            }
        }
        /* Update (SocketImpl)s' fd */
        fdAccess.set(s.fd, newfd);
        /* Update socketImpls remote port, address and localport */
        InetSocketAddress isa = isaa[0];
        s.port = isa.getPort();
        s.address = isa.getAddress();
        s.localport = localport;
    }

    int socketAvailable() throws IOException {
        int nativefd = checkAndReturnNativeFD();
        return available0(nativefd);
    }

    void socketClose0(boolean useDeferredClose/*unused*/) throws IOException {
        if (fd == null)
            throw new SocketException("Socket closed");

        if (!fd.valid())
            return;

        final int nativefd = fdAccess.get(fd);
        fdAccess.set(fd, -1);
        close0(nativefd);
    }

    void socketShutdown(int howto) throws IOException {
        int nativefd = checkAndReturnNativeFD();
        shutdown0(nativefd, howto);
    }

    // Intentional fallthrough after SO_REUSEADDR
    @SuppressWarnings("fallthrough")
    void socketSetOption(int opt, boolean on, Object value)
        throws SocketException {
        int nativefd = checkAndReturnNativeFD();

        if (opt == SO_TIMEOUT) {  // timeout implemented through select.
            return;
        }

        int optionValue = 0;

        switch(opt) {
            case SO_REUSEADDR :
                if (exclusiveBind) {
                    // SO_REUSEADDR emulated when using exclusive bind
                    isReuseAddress = on;
                    return;
                }
                // intentional fallthrough
            case TCP_NODELAY :
            case SO_OOBINLINE :
            case SO_KEEPALIVE :
                optionValue = on ? 1 : 0;
                break;
            case SO_SNDBUF :
            case SO_RCVBUF :
            case IP_TOS :
                optionValue = ((Integer)value).intValue();
                break;
            case SO_LINGER :
                if (on) {
                    optionValue =  ((Integer)value).intValue();
                } else {
                    optionValue = -1;
                }
                break;
            default :/* shouldn't get here */
                throw new SocketException("Option not supported");
        }

        setIntOption(nativefd, opt, optionValue);
    }

    int socketGetOption(int opt, Object iaContainerObj) throws SocketException {
        int nativefd = checkAndReturnNativeFD();

        // SO_BINDADDR is not a socket option.
        if (opt == SO_BINDADDR) {
            localAddress(nativefd, (InetAddressContainer)iaContainerObj);
            return 0;  // return value doesn't matter.
        }

        // SO_REUSEADDR emulated when using exclusive bind
        if (opt == SO_REUSEADDR && exclusiveBind)
            return isReuseAddress? 1 : -1;

        int value = getIntOption(nativefd, opt);

        switch (opt) {
            case TCP_NODELAY :
            case SO_OOBINLINE :
            case SO_KEEPALIVE :
            case SO_REUSEADDR :
                return (value == 0) ? -1 : 1;
        }
        return value;
    }

    void socketSendUrgentData(int data) throws IOException {
        int nativefd = checkAndReturnNativeFD();
        sendOOB(nativefd, data);
    }

    private int checkAndReturnNativeFD() throws SocketException {
        if (fd == null || !fd.valid())
            throw new SocketException("Socket closed");

        return fdAccess.get(fd);
    }

    static final int WOULDBLOCK = -2;       // Nothing available (non-blocking)

    static {
        initIDs();
    }

    /* Native methods */

    static native void initIDs();

    static native int socket0(boolean stream, boolean v6Only) throws IOException;

    static native void bind0(int fd, InetAddress localAddress, int localport,
                             boolean exclBind)
        throws IOException;

    static native int connect0(int fd, InetAddress remote, int remotePort)
        throws IOException;

    static native void waitForConnect(int fd, int timeout) throws IOException;

    static native int localPort0(int fd) throws IOException;

    static native void localAddress(int fd, InetAddressContainer in) throws SocketException;

    static native void listen0(int fd, int backlog) throws IOException;

    static native int accept0(int fd, InetSocketAddress[] isaa) throws IOException;

    static native void waitForNewConnection(int fd, int timeout) throws IOException;

    static native int available0(int fd) throws IOException;

    static native void close0(int fd) throws IOException;

    static native void shutdown0(int fd, int howto) throws IOException;

    static native void setIntOption(int fd, int cmd, int optionValue) throws SocketException;

    static native int getIntOption(int fd, int cmd) throws SocketException;

    static native void sendOOB(int fd, int data) throws IOException;

    static native void configureBlocking(int fd, boolean blocking) throws IOException;
}