ip route add bug in 1.25.0

[Timo Teras]

On Fri, 05 Aug 2016 16:29:30 +0100
Ron Yorston <rmy at pobox.com> wrote:

> Ron Yorston wrote:
> >Natanael Copa wrote:  
> >>$ sudo busybox ip route add 192.168.0.0/24 via 10.98.106.9 dev wlan0
> >>ip: RTNETLINK answers: Invalid argument  
> >
> >Reverting ce4bc1ed (iproute: support "scope". Closes 8561) seems to
> >make the problem go away.  
> 
> Specifically, this change causes the problem:
> 
> -               req.r.rtm_scope = RT_SCOPE_UNIVERSE;
> +               if (RT_SCOPE_UNIVERSE != 0)
> +                       req.r.rtm_scope = RT_SCOPE_UNIVERSE;
> 
> RT_SCOPE_UNIVERSE is zero, so req.r.rtm_scope isn't being initialised.
> 
> There are a number of similar constructs in this code, where the value
> of an enum is tested against zero.  I've no idea why.

Sounds like it's assuming the structure was previously initialized
to all zeroes, and it's intended as a micro optimization to avoid
writing zeroes again if the constant is zero.

Should probably just delete all those. Properly optimizing compiler
would handle that automatically.