1 /*

     2  * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package com.sun.jndi.ldap;

    27 

    28 import jdk.internal.misc.SharedSecrets;

    29 

    30 import java.net.MalformedURLException;

    31 import java.net.URL;

    32 import java.net.URLClassLoader;

    33 import java.security.AccessControlContext;

    34 import java.security.AccessController;

    35 import java.security.PrivilegedAction;

    36 

    37 public final class VersionHelper {

    38 

    39     private static final VersionHelper helper = new VersionHelper();

    40 

    41     /**

    42      * Determines whether classes may be loaded from an arbitrary URL code base.

    43      */

    44     private static final boolean trustURLCodebase;

    45 

    46     static {

    47         // System property to control whether classes may be loaded from an

    48         // arbitrary URL code base

    49         PrivilegedAction<String> act =

    50                 () -> System.getProperty("com.sun.jndi.ldap.object.trustURLCodebase", "false");

    51         String trust = AccessController.doPrivileged(act);

    52         trustURLCodebase = "true".equalsIgnoreCase(trust);

    53     }

    54 

    55     private VersionHelper() { }

    56 

    57     static VersionHelper getVersionHelper() {

    58         return helper;

    59     }

    60 

    61     ClassLoader getURLClassLoader(String[] url) throws MalformedURLException {

    62         ClassLoader parent = getContextClassLoader();

    63         /*

    64          * Classes may only be loaded from an arbitrary URL code base when

    65          * the system property com.sun.jndi.ldap.object.trustURLCodebase

    66          * has been set to "true".

    67          */

    68         if (url != null && trustURLCodebase) {

    69             return URLClassLoader.newInstance(getUrlArray(url), parent);

    70         } else {

    71             return parent;

    72         }

    73     }

    74 

    75     Class<?> loadClass(String className) throws ClassNotFoundException {

    76         return Class.forName(className, true, getContextClassLoader());

    77     }

    78 

    79     Thread createThread(Runnable r) {

    80         AccessControlContext acc = AccessController.getContext();

    81         // 4290486: doPrivileged is needed to create a thread in

    82         // an environment that restricts "modifyThreadGroup".

    83         PrivilegedAction<Thread> act =

    84                 () -> SharedSecrets.getJavaLangAccess().newThreadWithAcc(r, acc);

    85         return AccessController.doPrivileged(act);

    86     }

    87 

    88     private ClassLoader getContextClassLoader() {

    89         PrivilegedAction<ClassLoader> act =

    90                 Thread.currentThread()::getContextClassLoader;

    91         return AccessController.doPrivileged(act);

    92     }

    93 

    94     private static URL[] getUrlArray(String[] url) throws MalformedURLException {

    95         URL[] urlArray = new URL[url.length];

    96         for (int i = 0; i < urlArray.length; i++) {

    97             urlArray[i] = new URL(url[i]);

    98         }

    99         return urlArray;

   100     }

   101 }