test/jdk/java/net/InetAddress/IsReachableViaLoopbackTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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import java.io.IOException;
import java.net.InetAddress;
import java.net.NetworkInterface;

/**
 * @test
 * @bug 8135305
 * @key intermittent
 * @library /test/lib
 * @summary ensure we can't ping external hosts via loopback if
 * @run main IsReachableViaLoopbackTest
 */

public class IsReachableViaLoopbackTest {
    public static void main(String[] args) {
        try {
            InetAddress addr = InetAddress.getLoopbackAddress();
            InetAddress remoteAddr = InetAddress.getByName("23.197.138.208");  // use literal address to avoid DNS checks
            if (!addr.isReachable(10000))
                throw new RuntimeException("Localhost should always be reachable");
            NetworkInterface inf = NetworkInterface.getByInetAddress(addr);
            if (inf != null) {
                if (!addr.isReachable(inf, 20, 10000)) {
                    throw new RuntimeException("Localhost should always be reachable");
                } else {
                    System.out.println(addr + "  is reachable");
                }
                if (remoteAddr.isReachable(inf, 20, 10000)) {
                    throw new RuntimeException(remoteAddr + " is reachable");
                } else {
                    System.out.println(remoteAddr + "  is NOT reachable");
                }
            } else {
                System.out.println("inf == null");
            }
        } catch (IOException e) {
            throw new RuntimeException("Unexpected exception:" + e);
        }
        System.out.println("IsReachableViaLoopbackTest EXIT");
    }
}