[Bug 193246] Bug in IPv6 multicast join(), uncovered by Jenkins

[Craig Rodrigues]

On Wed, Sep 3, 2014 at 5:19 AM, Andrey V. Elsukov <ae at freebsd.org> wrote:
> On 03.09.2014 14:05, bugzilla-noreply at freebsd.org wrote:
>
> Hi,
>
> you said that this code works in linux. I looked in the linux kernel
> source, and I think it should return EINVAL too.
> net/ipv6/mcast.c:ipv6_sock_mc_join:
>
>  154         if (!ipv6_addr_is_multicast(addr))
>  155                 return -EINVAL;


The code does work in Linux.  However, you need to look at the
JDK source, not the Linux kernel source.

In this file:
http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/9b8c96f96a0f/src/solaris/native/java/net/PlainDatagramSocketImpl.c

in the mcast_join_leave() function, there are two code paths: (1)
Linux, (2) Solaris.

It looks like on Solaris, they support IPv4-mapped multicast addresses for IPV6,
and things work when they create an IPv6 socket, and then put an
IPv4-mapped multicast address in it.  For Linux, they have specific
code paths in that function which seem to force creating an IPv4
socket.

--
Craig