[OE-core] busybox: udhcpc: fix IPv6 support when using udhcpc

[Quentin Schulz]

Hi all,

On Mon, Jan 13, 2020 at 03:57:31PM +0100, Quentin Schulz wrote:
> Hi all,
> 
> On Mon, May 14, 2018 at 04:44:15PM +0200, Stefan Agner wrote:
> > From: Stefan Agner <stefan.agner at toradex.com>
> > 
> > The udhcpc script calls ip addr flush .. which flushes addresses
> > of any address family, including IPv6. However, busybox udhcpc is
> > IPv4 only and should not influence IPv6 addressing. Hence use ip
> > addr flush with family constrait.
> > 
> > The script particularly broke IPv6 SLAAC: Typically when udhcpc
> > calls the script the kernel already assigned the IPv6 link-local
> > address. The flush removes the link-local IPv6 address again and
> > prohibits proper IPv6 operation such as SLAAC since neighbor
> > discovery protocol relies on IPv6 link-local addressing.
> > 
> > Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
> > ---
> >  meta/recipes-core/busybox/files/simple.script | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/meta/recipes-core/busybox/files/simple.script b/meta/recipes-core/busybox/files/simple.script
> > index 6ed0293525..8b5eb53633 100644
> > --- a/meta/recipes-core/busybox/files/simple.script
> > +++ b/meta/recipes-core/busybox/files/simple.script
> > @@ -28,7 +28,7 @@ case "$1" in
> >  		fi
> >  		if ! root_is_nfs ; then
> >                          if [ $have_bin_ip -eq 1 ]; then
> > -                                /SBIN_DIR/ip addr flush dev $interface
> > +                                /SBIN_DIR/ip -4 addr flush dev $interface
> >                                  /SBIN_DIR/ip link set dev $interface up
> >                          else
> >                                  /SBIN_DIR/ifconfig $interface 0.0.0.0
> 
> Kindly pinging, happened to us as well many times.
> 

Kindly pinging.

Quentin