https://openjdk.java.net/ 
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 * Copyright (c) 1997, 2017, 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 javax.net.ssl;

import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.SocketException;
import javax.net.ServerSocketFactory;
import java.security.*;


SSLServerSocketFactorys create
SSLServerSockets.

Author:David Brownell
See Also:
Since:1.4
/**
 * <code>SSLServerSocketFactory</code>s create
 * <code>SSLServerSocket</code>s.
 *
 * @since 1.4
 * @see SSLSocket
 * @see SSLServerSocket
 * @author David Brownell
 */
public abstract class SSLServerSocketFactory extends ServerSocketFactory
{
    private static SSLServerSocketFactory theFactory;

    private static boolean propertyChecked;

    private static void log(String msg) {
        if (SSLSocketFactory.DEBUG) {
            System.out.println(msg);
        }
    }

    
Constructor is used only by subclasses.

/**
     * Constructor is used only by subclasses.
     */
    protected SSLServerSocketFactory() { /* NOTHING */ }

    
Returns the default SSL server socket factory.

The first time this method is called, the security property
"ssl.ServerSocketFactory.provider" is examined. If it is non-null, a
class by that name is loaded and instantiated. If that is successful and
the object is an instance of SSLServerSocketFactory, it is made the
default SSL server socket factory.

Otherwise, this method returns
SSLContext.getDefault().getServerSocketFactory(). If that
call fails, an inoperative factory is returned.

See Also:
Returns:the default ServerSocketFactory
/**
     * Returns the default SSL server socket factory.
     *
     * <p>The first time this method is called, the security property
     * "ssl.ServerSocketFactory.provider" is examined. If it is non-null, a
     * class by that name is loaded and instantiated. If that is successful and
     * the object is an instance of SSLServerSocketFactory, it is made the
     * default SSL server socket factory.
     *
     * <p>Otherwise, this method returns
     * <code>SSLContext.getDefault().getServerSocketFactory()</code>. If that
     * call fails, an inoperative factory is returned.
     *
     * @return the default <code>ServerSocketFactory</code>
     * @see SSLContext#getDefault
     */
    public static synchronized ServerSocketFactory getDefault() {
        if (theFactory != null) {
            return theFactory;
        }

        if (propertyChecked == false) {
            propertyChecked = true;
            String clsName = SSLSocketFactory.getSecurityProperty
                                        ("ssl.ServerSocketFactory.provider");
            if (clsName != null) {
                log("setting up default SSLServerSocketFactory");
                try {
                    Class<?> cls = null;
                    try {
                        cls = Class.forName(clsName);
                    } catch (ClassNotFoundException e) {
                        ClassLoader cl = ClassLoader.getSystemClassLoader();
                        if (cl != null) {
                            cls = cl.loadClass(clsName);
                        }
                    }
                    log("class " + clsName + " is loaded");
                    @SuppressWarnings("deprecation")
                    SSLServerSocketFactory fac = (SSLServerSocketFactory)cls.newInstance();
                    log("instantiated an instance of class " + clsName);
                    theFactory = fac;
                    return fac;
                } catch (Exception e) {
                    log("SSLServerSocketFactory instantiation failed: " + e);
                    theFactory = new DefaultSSLServerSocketFactory(e);
                    return theFactory;
                }
            }
        }

        try {
            return SSLContext.getDefault().getServerSocketFactory();
        } catch (NoSuchAlgorithmException e) {
            return new DefaultSSLServerSocketFactory(e);
        }
    }

    
Returns the list of cipher suites which are enabled by default.
Unless a different list is enabled, handshaking on an SSL connection
will use one of these cipher suites.  The minimum quality of service
for these defaults requires confidentiality protection and server
authentication (that is, no anonymous cipher suites).


The returned array includes cipher suites from the list of standard
cipher suite names in the 
JSSE Cipher Suite Names section of the Java Cryptography
Architecture Standard Algorithm Name Documentation, and may also
include other cipher suites that the provider supports.

See Also:
Returns:array of the cipher suites enabled by default
/**
     * Returns the list of cipher suites which are enabled by default.
     * Unless a different list is enabled, handshaking on an SSL connection
     * will use one of these cipher suites.  The minimum quality of service
     * for these defaults requires confidentiality protection and server
     * authentication (that is, no anonymous cipher suites).
     * <P>
     * The returned array includes cipher suites from the list of standard
     * cipher suite names in the <a href=
     * "{@docRoot}/../specs/security/standard-names.html#jsse-cipher-suite-names">
     * JSSE Cipher Suite Names</a> section of the Java Cryptography
     * Architecture Standard Algorithm Name Documentation, and may also
     * include other cipher suites that the provider supports.
     *
     * @see #getSupportedCipherSuites()
     * @return array of the cipher suites enabled by default
     */
    public abstract String [] getDefaultCipherSuites();


    
Returns the names of the cipher suites which could be enabled for use
on an SSL connection created by this factory.
Normally, only a subset of these will actually
be enabled by default, since this list may include cipher suites which
do not meet quality of service requirements for those defaults.  Such
cipher suites are useful in specialized applications.


The returned array includes cipher suites from the list of standard
cipher suite names in the 
JSSE Cipher Suite Names section of the Java Cryptography
Architecture Standard Algorithm Name Documentation, and may also
include other cipher suites that the provider supports.

See Also:
Returns:an array of cipher suite names
/**
     * Returns the names of the cipher suites which could be enabled for use
     * on an SSL connection created by this factory.
     * Normally, only a subset of these will actually
     * be enabled by default, since this list may include cipher suites which
     * do not meet quality of service requirements for those defaults.  Such
     * cipher suites are useful in specialized applications.
     * <P>
     * The returned array includes cipher suites from the list of standard
     * cipher suite names in the <a href=
     * "{@docRoot}/../specs/security/standard-names.html#jsse-cipher-suite-names">
     * JSSE Cipher Suite Names</a> section of the Java Cryptography
     * Architecture Standard Algorithm Name Documentation, and may also
     * include other cipher suites that the provider supports.
     *
     * @return an array of cipher suite names
     * @see #getDefaultCipherSuites()
     */
    public abstract String [] getSupportedCipherSuites();
}


//
// The default factory does NOTHING.
//
class DefaultSSLServerSocketFactory extends SSLServerSocketFactory {

    private final Exception reason;

    DefaultSSLServerSocketFactory(Exception reason) {
        this.reason = reason;
    }

    private ServerSocket throwException() throws SocketException {
        throw (SocketException)
            new SocketException(reason.toString()).initCause(reason);
    }

    @Override
    public ServerSocket createServerSocket() throws IOException {
        return throwException();
    }


    @Override
    public ServerSocket createServerSocket(int port)
    throws IOException
    {
        return throwException();
    }

    @Override
    public ServerSocket createServerSocket(int port, int backlog)
    throws IOException
    {
        return throwException();
    }

    @Override
    public ServerSocket
    createServerSocket(int port, int backlog, InetAddress ifAddress)
    throws IOException
    {
        return throwException();
    }

    @Override
    public String [] getDefaultCipherSuites() {
        return new String[0];
    }

    @Override
    public String [] getSupportedCipherSuites() {
        return new String[0];
    }
}