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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
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 * by Oracle in the LICENSE file that accompanied this code.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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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.*;

/**
 * <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 {

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

    /**
     * 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 ServerSocketFactory getDefault() {
        if (DefaultFactoryHolder.defaultFactory != null) {
            return DefaultFactoryHolder.defaultFactory;
        }

        try {
            return SSLContext.getDefault().getServerSocketFactory();
        } catch (NoSuchAlgorithmException | UnsupportedOperationException 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).
     * <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 Security Standard
     * Algorithm Names Specification, 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.
     * <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 Security Standard
     * Algorithm Names Specification, and may also include other cipher
     * suites that the provider supports.
     *
     * @return an array of cipher suite names
     * @see #getDefaultCipherSuites()
     */
    public abstract String [] getSupportedCipherSuites();

    // lazy initialization holder class idiom for static default factory
    //
    // See Effective Java Second Edition: Item 71.
    private static final class DefaultFactoryHolder {
        private static final SSLServerSocketFactory defaultFactory;

        static {
            SSLServerSocketFactory mediator = null;
            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");

                    mediator = (SSLServerSocketFactory)cls
                            .getDeclaredConstructor().newInstance();
                    log("instantiated an instance of class " + clsName);
                } catch (Exception e) {
                    log("SSLServerSocketFactory instantiation failed: " + e);
                    mediator = new DefaultSSLServerSocketFactory(e);
                }
            }

            defaultFactory = mediator;
        }

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

//
// 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 new SocketException(reason.toString(), 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];
    }
}
