DnsServerAddressStreamProviders.java — netty Source File

Source Code

/*
 * Copyright 2017 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.resolver.dns;

import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Utility methods related to {@link DnsServerAddressStreamProvider}.
 */
public final class DnsServerAddressStreamProviders {

    private static final InternalLogger LOGGER =
            InternalLoggerFactory.getInstance(DnsServerAddressStreamProviders.class);
    private static final Constructor<? extends DnsServerAddressStreamProvider> STREAM_PROVIDER_CONSTRUCTOR;
    private static final String MACOS_PROVIDER_CLASS_NAME =
            "io.netty.resolver.dns.macos.MacOSDnsServerAddressStreamProvider";

    static {
        Constructor<? extends DnsServerAddressStreamProvider> constructor = null;
        if (PlatformDependent.isOsx()) {
            try {
                // As MacOSDnsServerAddressStreamProvider is contained in another jar which depends on this jar
                // we use reflection to use it if its on the classpath.
                Object maybeProvider = AccessController.doPrivileged(new PrivilegedAction<Object>() {
                    @Override
                    public Object run() {
                        try {
                            return Class.forName(
                                    MACOS_PROVIDER_CLASS_NAME,
                                    true,
                                    DnsServerAddressStreamProviders.class.getClassLoader());
                        } catch (Throwable cause) {
                            return cause;
                        }
                    }
                });
                if (maybeProvider instanceof Class) {
                    @SuppressWarnings("unchecked")
// ... (92 more lines)