Name: gm110360 Date: 06/23/2004


FULL PRODUCT VERSION :
java version "1.5.0-beta2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta2-b51)
Java HotSpot(TM) Client VM (build 1.5.0-beta2-b51, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
Laptop with wireless LAN (turned off) and 100-base-T cable (plugged in and operating)

A DESCRIPTION OF THE PROBLEM :
I have a very simple program that tries to isReachable() a host on the LAN (see sample).
If I unplug *my* network connection, I get 3 "unreachable" messages, followed by a stream of "reachable" messages (WRONG), and then a whole load of IOExceptions.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Modify buggy\ReachableTest.java to point to a host that is alive and well on your network (ie that will respond to a isReachable() request).

javac buggy\ReachableTest.java
java buggy.ReachableTest

Pull the network cable from the same machine you are running ReachableTest from.

See the "not reachable" message pop up
THen see lots of "reachable" messages pop up.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
When the LAN cable is pulled, isReachable() should not return true.
ACTUAL -
When the LAN cable is pulled, isReachable() returned 3 "false"s (correct response), but then lots of "true"s.
I suspect the code internally is getting a "unreachable destination" response, and interpreting it as "we got a response, so it is reachable".

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package buggy;

import java.net.InetAddress;
import java.net.*;
import java.io.IOException;

public class ReachableTest
{
    boolean packFrame = false;

    //Main method
    public static void main(String[] args)
    {
byte[] addr =
{
(byte) 192, (byte) 168, 1, 1};
InetAddress inetaddr = null;
try
{
inetaddr = InetAddress.getByAddress(addr);
}
catch (UnknownHostException ex)
{
System.out.println("Java took exception to my address!");
}
while (true)
{
try
{
if (inetaddr.isReachable(2000))
{
System.out.println("reachable");
}
else
{
System.out.println("not reachable");
}
}
catch (IOException ex)
{
System.out.println("We got an IOException");
}
}
    }
}
---------- END SOURCE ----------
(Incident Review ID: 280614)
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