Java example source code file (ProviderConfig.java)

This example Java source code file (ProviderConfig.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

boolean, cl_string, class, classloader, file, max_load_tries, object, p11_sol_arg, p11_sol_name, privilegedaction, provider, providerconfig, providerexception, reflection, security, string

The ProviderConfig.java Java example source code

/*
 * Copyright (c) 2003, 2009, 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 sun.security.jca;

import java.io.File;
import java.lang.reflect.*;

import java.security.*;

import sun.security.util.PropertyExpander;

/**
 * Class representing a configured provider. Encapsulates configuration
 * (className plus optional argument), the provider loading logic, and
 * the loaded Provider object itself.
 *
 * @author  Andreas Sterbenz
 * @since   1.5
 */
final class ProviderConfig {

    private final static sun.security.util.Debug debug =
        sun.security.util.Debug.getInstance("jca", "ProviderConfig");

    // classname of the SunPKCS11-Solaris provider
    private static final String P11_SOL_NAME =
        "sun.security.pkcs11.SunPKCS11";

    // config file argument of the SunPKCS11-Solaris provider
    private static final String P11_SOL_ARG  =
        "${java.home}/lib/security/sunpkcs11-solaris.cfg";

    // maximum number of times to try loading a provider before giving up
    private final static int MAX_LOAD_TRIES = 30;

    // parameters for the Provider(String) constructor,
    // use by doLoadProvider()
    private final static Class[] CL_STRING = { String.class };

    // name of the provider class
    private final String className;

    // argument to the provider constructor,
    // empty string indicates no-arg constructor
    private final String argument;

    // number of times we have already tried to load this provider
    private int tries;

    // Provider object, if loaded
    private volatile Provider provider;

    // flag indicating if we are currently trying to load the provider
    // used to detect recursion
    private boolean isLoading;

    ProviderConfig(String className, String argument) {
        if (className.equals(P11_SOL_NAME) && argument.equals(P11_SOL_ARG)) {
            checkSunPKCS11Solaris();
        }
        this.className = className;
        this.argument = expand(argument);
    }

    ProviderConfig(String className) {
        this(className, "");
    }

    ProviderConfig(Provider provider) {
        this.className = provider.getClass().getName();
        this.argument = "";
        this.provider = provider;
    }

    // check if we should try to load the SunPKCS11-Solaris provider
    // avoid if not available (pre Solaris 10) to reduce startup time
    // or if disabled via system property
    private void checkSunPKCS11Solaris() {
        Boolean o = AccessController.doPrivileged(
                                new PrivilegedAction<Boolean>() {
            public Boolean run() {
                File file = new File("/usr/lib/libpkcs11.so");
                if (file.exists() == false) {
                    return Boolean.FALSE;
                }
                if ("false".equalsIgnoreCase(System.getProperty
                        ("sun.security.pkcs11.enable-solaris"))) {
                    return Boolean.FALSE;
                }
                return Boolean.TRUE;
            }
        });
        if (o == Boolean.FALSE) {
            tries = MAX_LOAD_TRIES;
        }
    }

    private boolean hasArgument() {
        return argument.length() != 0;
    }

    // should we try to load this provider?
    private boolean shouldLoad() {
        return (tries < MAX_LOAD_TRIES);
    }

    // do not try to load this provider again
    private void disableLoad() {
        tries = MAX_LOAD_TRIES;
    }

    boolean isLoaded() {
        return (provider != null);
    }

    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof ProviderConfig == false) {
            return false;
        }
        ProviderConfig other = (ProviderConfig)obj;
        return this.className.equals(other.className)
            && this.argument.equals(other.argument);
    }

    public int hashCode() {
        return className.hashCode() + argument.hashCode();
    }

    public String toString() {
        if (hasArgument()) {
            return className + "('" + argument + "')";
        } else {
            return className;
        }
    }

    /**
     * Get the provider object. Loads the provider if it is not already loaded.
     */
    synchronized Provider getProvider() {
        // volatile variable load
        Provider p = provider;
        if (p != null) {
            return p;
        }
        if (shouldLoad() == false) {
            return null;
        }
        if (isLoading) {
            // because this method is synchronized, this can only
            // happen if there is recursion.
            if (debug != null) {
                debug.println("Recursion loading provider: " + this);
                new Exception("Call trace").printStackTrace();
            }
            return null;
        }
        try {
            isLoading = true;
            tries++;
            p = doLoadProvider();
        } finally {
            isLoading = false;
        }
        provider = p;
        return p;
    }

    /**
     * Load and instantiate the Provider described by this class.
     *
     * NOTE use of doPrivileged().
     *
     * @return null if the Provider could not be loaded
     *
     * @throws ProviderException if executing the Provider's constructor
     * throws a ProviderException. All other Exceptions are ignored.
     */
    private Provider doLoadProvider() {
        return AccessController.doPrivileged(new PrivilegedAction<Provider>() {
            public Provider run() {
                if (debug != null) {
                    debug.println("Loading provider: " + ProviderConfig.this);
                }
                try {
                    ClassLoader cl = ClassLoader.getSystemClassLoader();
                    Class<?> provClass;
                    if (cl != null) {
                        provClass = cl.loadClass(className);
                    } else {
                        provClass = Class.forName(className);
                    }
                    Object obj;
                    if (hasArgument() == false) {
                        obj = provClass.newInstance();
                    } else {
                        Constructor<?> cons = provClass.getConstructor(CL_STRING);
                        obj = cons.newInstance(argument);
                    }
                    if (obj instanceof Provider) {
                        if (debug != null) {
                            debug.println("Loaded provider " + obj);
                        }
                        return (Provider)obj;
                    } else {
                        if (debug != null) {
                            debug.println(className + " is not a provider");
                        }
                        disableLoad();
                        return null;
                    }
                } catch (Exception e) {
                    Throwable t;
                    if (e instanceof InvocationTargetException) {
                        t = ((InvocationTargetException)e).getCause();
                    } else {
                        t = e;
                    }
                    if (debug != null) {
                        debug.println("Error loading provider " + ProviderConfig.this);
                        t.printStackTrace();
                    }
                    // provider indicates fatal error, pass through exception
                    if (t instanceof ProviderException) {
                        throw (ProviderException)t;
                    }
                    // provider indicates that loading should not be retried
                    if (t instanceof UnsupportedOperationException) {
                        disableLoad();
                    }
                    return null;
                }
            }
        });
    }

    /**
     * Perform property expansion of the provider value.
     *
     * NOTE use of doPrivileged().
     */
    private static String expand(final String value) {
        // shortcut if value does not contain any properties
        if (value.contains("${") == false) {
            return value;
        }
        return AccessController.doPrivileged(new PrivilegedAction<String>() {
            public String run() {
                try {
                    return PropertyExpander.expand(value);
                } catch (GeneralSecurityException e) {
                    throw new ProviderException(e);
                }
            }
        });
    }

}