rsync 2.6.2 --daemon Problem

[Jan-Benedict Glaw]

On Wed, 2004-05-05 14:44:49 -0400, Gregory Symons <gsymons at gsconsulting.biz>
wrote in message <1083782689.13688.29.camel at odysseus.internal.gsconsulting.biz>:
> On Wed, 2004-05-05 at 04:02, Paul Slootman wrote:

> But in Linux, IPV6_V6ONLY socket option does not exist in kernel2.4.20
> or earlier, except for USAGI kernels. Therefore, you can't do a bind(2)
> of IPv4/IPv6 wildcard address to the same port. Therefore, you would
> bind(2) only IPv6 wildcard address, and handle IPv4 traffic via
> IPv4-mapped address with the same socket.

Right, Linux' IPv6 implementation, especially in 2.4.x, is buggy.

> <http://www.ipv6style.jp/en/apps/20030829/index.shtml>
> 
> And I am indeed running a 2.4.20 kernel. So maybe the configure script
> needs to detect whether or not this flag is actually available (which I
> thought was the point of the #ifdef), rather than trusting the fact that
> the macro itself is defined. Otherwise, if IPV6 _is_ available, but

Well, that depends...

> IPV6_IPV6ONLY option is not, using the patch you sent would cause us to
> skip any IPV6 addresses that we want to bind to.

rsync (as other programs) should ./configure to adopt it's host system's
libc API. That is, if libc offers IPV6_V6ONLY, rsync should accept that
fact and use it {properly,if needed}. So if there's a (detectable) bug,
let's complain about it, but please accept the presented API.

If really a workaround is needed, rsync should detect that error *at
runtime*, complain loudly and exit (offering some
--use-broken-linux-2.4.x-ipv6-stack) for allowing it to work properly.

Runtime check? Right. Think about distributions that offer both 2.4.x
and 2.6.x. For sure you won't like to deliver two rsync versions to your
users:) ...and because IPV6_V6ONLY exists in 2.4.21 upwards, I think
that's not a major problem. Hey, these kernels do have known root
exploits, so it's time for an update!

So if there's a but, don't hide it, but work towards fixing it.

MfG, JBG

-- 
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