net.lightbody.bmp.proxy.dns.NativeResolver Maven / Gradle / Ivy

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package net.lightbody.bmp.proxy.dns;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

/**
 * An {@link net.lightbody.bmp.proxy.dns.AdvancedHostResolver} that provides native JVM lookup using {@link java.net.InetAddress}.
 * This implementation does not provide any cache manipulation. Attempting to manipulate the DNS cache will result in a DEBUG-level
 * log statement and will not raise an exception. The {@link net.lightbody.bmp.proxy.dns.DnsJavaResolver} provides support for cache
 * manipulation. If you absolutely need to manipulate the native JVM DNS cache, see
 * {@link net.lightbody.bmp.proxy.dns.NativeCacheManipulatingResolver} for details.
 */
public class NativeResolver extends AbstractHostNameRemapper implements AdvancedHostResolver {
	private static final Logger log = LoggerFactory.getLogger(NativeResolver.class);

	@Override
	public void clearDNSCache() {
		log.debug("Cannot clear native JVM DNS Cache using this Resolver");
	}

	@Override
	public void setPositiveDNSCacheTimeout(int timeout, TimeUnit timeUnit) {
		log.debug("Cannot change native JVM DNS cache timeout using this Resolver");
	}

	@Override
	public void setNegativeDNSCacheTimeout(int timeout, TimeUnit timeUnit) {
		log.debug("Cannot change native JVM DNS cache timeout using this Resolver");
	}

	@Override
	public Collection resolveRemapped(String remappedHost) {
		try {
			Collection addresses = Arrays.asList(InetAddress.getAllByName(remappedHost));

			return addresses;
		} catch (UnknownHostException e) {
			return Collections.emptyList();
		}
	}
}