AF_INET6 support

[Chris Hegarty]

Christoph,

> On 13 Oct 2016, at 07:19, Langer, Christoph <christoph.langer at sap.com> wrote:
> 
> Hi networking experts,
>  
> I’ve got a question regarding AF_INET6.
>  
> In jdk native code you’ll still find lots of code guarded by  “#ifdef AF_INET6”. I’m wondering if there are still supported build environments where AF_INET6 is not defined. Or is it time now to assume AF_INET6 and remove this guarding? Here at SAP we don’t support non AF_INET6 build environments for quite a long time already. But probably there are scenarios out in the Java world where only IPv4 builds are done??
>  
> Maybe you can shed some light on this and/or give your opinion?

A while back we did consider removing #ifdef AF_INET6, so that the
code could be cleaned up and made more readable, but we never got
around to it ( it was just lower priority than other tasks ).  I do remember
fixing, or sponsoring, a change in the last year or so, where an #ifdef
AF_INET6 was missing, that make me think that it was good that we
did not remove these ( i.e. the person that filed the bug had a good
use-case for building without IPv6 support ). I’ll see if I can jog my 
memory by looking through history.

-Chris.