Java tutorial
/* * Copyright (c) 1997, 2019, 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 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 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. * <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(); // 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 (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]; } }