--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.naming/share/classes/com/sun/jndi/ldap/LdapDnsProviderService.java	Mon Nov 12 08:33:59 2018 -0800
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2018, 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 com.sun.jndi.ldap;
+
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.*;
+import javax.naming.NamingException;
+import javax.naming.ldap.spi.LdapDnsProvider;
+import javax.naming.ldap.spi.LdapDnsProviderResult;
+import sun.security.util.SecurityConstants;
+
+/**
+ * The {@code LdapDnsProviderService} is responsible for creating and providing
+ * access to the registered {@code LdapDnsProvider}s. The {@link ServiceLoader}
+ * is used to find and register any implementations of {@link LdapDnsProvider}.
+ */
+final class LdapDnsProviderService {
+
+    private static volatile LdapDnsProviderService service;
+    private static final Object LOCK = new int[0];
+    private final ServiceLoader<LdapDnsProvider> providers;
+
+    /**
+     * Creates a new instance of LdapDnsProviderService
+     */
+    private LdapDnsProviderService() {
+        SecurityManager sm = System.getSecurityManager();
+        if (sm == null) {
+            providers = ServiceLoader.load(
+                    LdapDnsProvider.class,
+                    ClassLoader.getSystemClassLoader());
+        } else {
+            final PrivilegedAction<ServiceLoader<LdapDnsProvider>> pa =
+                    () -> ServiceLoader.load(
+                            LdapDnsProvider.class,
+                            ClassLoader.getSystemClassLoader());
+
+            providers = AccessController.doPrivileged(
+                pa,
+                null,
+                new RuntimePermission("ldapDnsProvider"),
+                SecurityConstants.GET_CLASSLOADER_PERMISSION);
+        }
+    }
+
+    /**
+     * Retrieve the singleton static instance of LdapDnsProviderService.
+     */
+    static LdapDnsProviderService getInstance() {
+        if (service != null) return service;
+        synchronized(LOCK) {
+            if (service != null) return service;
+            service = new LdapDnsProviderService();
+        }
+        return service;
+    }
+
+    /**
+     * Retrieve result from the first provider that successfully resolves
+     * the endpoints. If no results are found when calling installed
+     * subclasses of {@code LdapDnsProvider} then this method will fall back
+     * to the {@code DefaultLdapDnsProvider}.
+     *
+     * @throws NamingException if the {@code url} in not valid or an error
+     *                         occurred while performing the lookup.
+     */
+    LdapDnsProviderResult lookupEndpoints(String url, Hashtable<?,?> env)
+        throws NamingException
+    {
+        Iterator<LdapDnsProvider> iterator = providers.iterator();
+        Hashtable<?, ?> envCopy = new Hashtable<>(env);
+        LdapDnsProviderResult result = null;
+
+        while (result == null && iterator.hasNext()) {
+            result = iterator.next().lookupEndpoints(url, envCopy)
+                    .filter(r -> r.getEndpoints().size() > 0)
+                    .orElse(null);
+        }
+
+        if (result == null) {
+            return new DefaultLdapDnsProvider().lookupEndpoints(url, env)
+                .orElse(new LdapDnsProviderResult("", List.of()));
+        }
+        return result;
+    }
+
+}