LocalManagedDnsProxy.java

/* 
 * Licensed 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
 *
 *      http://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 org.ngrinder.dns;

import sun.net.spi.nameservice.NameService;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Set;

/**
 * Locally managed DNS.
 *
 * @author JunHo Yoon
 * @since 3.0
 */
@SuppressWarnings({"restriction", "WeakerAccess"})
public class LocalManagedDnsProxy implements NameService {
	private final NameService defaultDnsImpl = new LocalManagedDnsImpl();
	private final NameStore instance = NameStore.getInstance();

	/**
	 * Get host name by address.
	 *
	 * @param ip ip
	 * @return host name
	 * @throws UnknownHostException occurs when hostname can not be found.
	 * @see sun.net.spi.nameservice.NameService#getHostByAddr(byte[])
	 */
	public String getHostByAddr(byte[] ip) throws UnknownHostException {
		String hostName = instance.getReveredHost(InetAddress.getByAddress(ip));
		if (hostName == null) {
			return defaultDnsImpl.getHostByAddr(ip);
		} else {
			return hostName;
		}
	}

	/**
	 * Get InetAddresses by hostname.
	 *
	 * @param name hostname
	 * @return ip addresses
	 * @throws UnknownHostException occurs when hostname can not be found.
	 * @see sun.net.spi.nameservice.NameService#getHostByAddr(byte[])
	 */
	public InetAddress[] lookupAllHostAddr(String name) throws UnknownHostException {
		Set<InetAddress> ipAddresses = instance.get(name);
		if (ipAddresses != null) {
			return DnsUtils.shuffle(ipAddresses.toArray(new InetAddress[ipAddresses.size()]));
		} else {
			return defaultDnsImpl.lookupAllHostAddr(name);
		}
	}

}