On Fri, 28 Aug 2026 18:04:41 +0200
Alessio Faina <[email protected]> wrote:
> [snip]
>
Hi Alessio,
> I tried multiple methods:
> the first approach is yours, but I can see the following error with any
> iproute2
> version I'm using (I tried 5.5 to 5.18): when running
> "ip -netns ${rtdst_name}" command, it always returns
>
> RTNETLINK answers: File exists
> 2
EEXIST means that the object is already there, and says nothing about
vrftable. When ip does not know vrftable it refuses the command itself,
with the error you showed earlier: either "to" is duplicate,
or "vrftable" is a garbage.
In a netns created by the check there is nothing to collide with, so EEXIST
does not come from the way I suggested. The full command and output would
settle it.
> I tried the following approach as well,
>
> # set the decap route for decapsulating packets which arrive from
> # the rtdst router and destined to the hsdst host.
> - ip -netns ${rtdst_name} -6 route add ${vpn_sid}/128 table
> ${LOCALSID_TABLE_ID} \
> - encap seg6local action End.DT4 vrftable ${tid} dev vrf-${tid}
> + if ! ip -netns ${rtdst_name} -6 route add ${vpn_sid}/128 table
> ${LOCALSID_TABLE_ID} \
> + encap seg6local action End.DT4 vrftable ${tid} dev
> vrf-${tid} 2>/dev/null; then
> + echo "SKIP: SRv6 End.DT4 vrftable not supported in iproute2"
> + cleanup
> + exit "${ksft_skip}"
> + fi
>
> where the test is checked at vrftable creation time, and it would
> cleanup and exit as expected from standard tests.
>
> But obviously this gets the same RTNETLINK answer as an error.
>
This is a setup step, not a check. The skip decision is taken while the
topology is being built, because setup_vpn_config() is called several times
inside setup(). The check should run before setup(), once.
The way I suggested runs the route add with vrftable in a throwaway netns,
created and removed by the check itself.
test_encap_lookup_supp_or_ksft_skip() in srv6_encap_lookup_l3vpn_test.sh
has that shape: it creates the netns, adds the device it needs, tries its
route, and on failure cleans up and exits ksft_skip. For the dt4 and dt6
tests that device is a vrf bound to the table passed to vrftable, and the
netns also needs the strict mode.
> Then another approach came to my mind, and it seems to be quite reliable.
> Practically checking if the ip command contains the string "vrftable"
> using the "strings" command, and if not, skip the test.
>
> Something like this:
>
> +test_iproute2_vrftable_supp_or_ksft_skip()
> +{
> + if ! strings $(command -v ip) | grep -q "vrftable"; then
> + echo "SKIP: SRv6 End.DT4 vrftable not supported in iproute2"
> + exit "${ksft_skip}"
> + fi
> +}
> +
>
> What do you think about it?
I would rather not add a new tool dependency to these two tests. The
route add uses ip, which the test needs anyway.
Ciao,
Andrea
