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
26package com.sun.jndi.ldap;
27
28import jdk.internal.misc.SharedSecrets;
29
30import java.net.MalformedURLException;
31import java.net.URL;
32import java.net.URLClassLoader;
33import java.security.AccessControlContext;
34import java.security.AccessController;
35import java.security.PrivilegedAction;
36
37public 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}
102