JDP broadcaster issue

[Yasumasa Suenaga]

Hi all,

I'm trying to use JDP on my Fedora20 machine.
My machine has two NICs and only one NIC is up.

I passed system properties as below, however JDP broadcaster
thread was not started:

  -Dcom.sun.management.jmxremote.port=7091
  -Dcom.sun.management.jmxremote.authenticate=false
  -Dcom.sun.management.jmxremote.ssl=false
  -Dcom.sun.management.jmxremote.autodiscovery=true
  -Dcom.sun.management.jdp.name=TEST

I checked exceptions with jdb, SocketException was occurred in
JDPControllerRunner#run(), and it was caused by another NIC
is down.

Currently, DiagramChannel which is used in JDPBroadcaster
tries to send JDP packet through all "UP" NICs.
However, NIC which is controlled by NetworkManager seems to
be still "UP" when ifdown command is executed.
(It seems to be removed IP address from NIC only.)


This problem may be Fedora, however I think it should be
improved in JDK.
I've created a patch as below, and it works fine in my environment.
(jdk9/dev/jdk)

If this patch may be accepted, I will file this to JBS.

--------------------
diff -r 68a6bb51cb26 src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java
--- a/src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java	Mon Sep 01 13:33:28 2014 +0200
+++ b/src/java.management/share/classes/sun/management/jdp/JdpBroadcaster.java	Tue Sep 02 23:25:50 2014 +0900
@@ -35,6 +35,7 @@
 import java.nio.ByteBuffer;
 import java.nio.channels.DatagramChannel;
 import java.nio.channels.UnsupportedAddressTypeException;
+import java.util.Enumeration;
 
 /**
  * JdpBroadcaster is responsible for sending pre-built JDP packet across a Net
@@ -79,6 +80,15 @@
         if (srcAddress != null) {
             // User requests particular interface to bind to
             NetworkInterface interf = NetworkInterface.getByInetAddress(srcAddress);
+
+            if (interf == null) {
+                throw new JdpException("Unable to get network interface for " + srcAddress.toString());
+            }
+
+            if (!interf.isUp() || !interf.supportsMulticast()) {
+                throw new JdpException(interf.getName() + " does not support multicast.");
+            }
+
             try {
                 channel.bind(new InetSocketAddress(srcAddress, 0));
             } catch (UnsupportedAddressTypeException ex) {
@@ -86,6 +96,23 @@
             }
             channel.setOption(StandardSocketOptions.IP_MULTICAST_IF, interf);
         }
+        else {
+            Enumeration<NetworkInterface> nics = NetworkInterface.getNetworkInterfaces();
+            while (nics.hasMoreElements()) {
+                NetworkInterface nic = nics.nextElement();
+
+                if (nic.isUp() && nic.supportsMulticast()) {
+                    try {
+                        channel.setOption(StandardSocketOptions.IP_MULTICAST_IF, nic);
+                    } catch (IOException ex) {
+                        System.err.println("WARNING: JDP broadcaster cannot use " + nic.getName() + ": " + ex.getMessage());
+                    }
+                }
+
+            }
+
+        }
+
     }
 
     /**
--------------------


Thanks,

Yasumasa