[Buildroot] [PATCH 3/3] package/python-iptables: use installed iptables by default
Frank Vanbever
frank.vanbever at essensium.com
Fri Feb 28 16:17:20 UTC 2020
Hi Thomas,
> I'll see if I can whip something up and submit it upstream.
I gave it another try but it seems that I was a bit too optimistic yesterday.
The xtables module requires the ABI version to cast the return values for
matches and targets to something it can access.
I have a final last ditch theory about how this could be fixed, but to be honest
it's really starting to look like more trouble than it's worth.
The ABI version information is embedded into struct xtables_match and
struct xtables_target. You should be able to get to these just from a handle
to the libxtables.so and the location of the iptables extensions (i.e.
xtables_libdir), for which you could use the same solution as for libc and
test a number of sensible locations if ldconfig is unavailable.
The xtables_{match,target} structs always have the version field as the first
field in the returned struct so I think you could do an
xtables_find_{target,match} and do a ctypes.cast to a dummy ctypes.struct class
with just the version field.
The way the module is written though requires the ABI version global variable
to instantiate the xtables class which contains the logic that would allow you
to find a match/target. So you get into this chicken or the egg type situation
where you need to know the ABI version to get the workaround way to get the
ABI version to work.
Best regards,
Frank
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