Hi Christoph,

OS X has a issue that needs "always" add a sin6_scope_id a multicast packet, I 
check that exists a old issue that logged it and add that piece of code: 

The DefaultInterface class in OS X is a plain Java class that list all 
interfaces and discards loopback and ppp interfaces, and prefers multistack 
interfaces than ones with only IPv4. I think that this class must use the 
network interface order defined in System Configuration but I don't find a way 
to use it.

I already signed the OCA, then I would like to have your help.

El 11/04/2018 a las 04:42, Langer, Christoph escribió:
Hi Joel,

your fix sounds reasonable. In fact, I'm not even sure if the sin6_scope_id 
should be set for multicast. Maybe it should be done only for link local 

Additionally, I guess the selection of the default interface (for IPv6) should 
be improved because I still can imagine a scenario where the first interface 
only has IPv4 but you want to do an IPv6 link local connect where you need a 

Do you have signed an OCA as per [1], section "0. Become a Contributor"? Then I 
can help you with sponsoring this...

Best regards

[1] http://openjdk.java.net/contribute/

-----Original Message-----
From: net-dev [mailto:net-dev-boun...@openjdk.java.net] On Behalf Of
Joel Peláez Jorge
Sent: Dienstag, 10. April 2018 00:37
To: net-dev@openjdk.java.net
Subject: JDK-8200719: Cannot connect to IPv6 host when exists any active
network interface without IPv6 address


I am new in the OpenJDK Community and I contribute with a fix for the bug
8200719 related to networking in macOS system.

I wrote a minimal patch that only set the scope id when the address is link-
local or multicast. This change avoid send IPv6 packets on a wrong interface.

Bug: https://bugs.openjdk.java.net/browse/JDK-8200719


diff -r f088ec60bed5 src/java.base/unix/native/libnet/net_util_md.c
--- a/src/java.base/unix/native/libnet/net_util_md.c Mon Apr 09 10:39:29
2018 -0700
+++ b/src/java.base/unix/native/libnet/net_util_md.c Mon Apr 09 16:50:18
2018 -0500
@@ -89,7 +89,8 @@
       int defaultIndex;
       struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)him;
-    if (sin6->sin6_family == AF_INET6 && (sin6->sin6_scope_id == 0)) {
+    if (sin6->sin6_family == AF_INET6 && (sin6->sin6_scope_id == 0) &&
+        (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))) {
           defaultIndex = (*env)->GetStaticIntField(env, ni_class,
           sin6->sin6_scope_id = defaultIndex;


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