[MPTCP] Re: [bug report] the test cases for signaling invalid addresses don't work

[Geliang Tang <geliangtang at gmail.com>]

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Hi Paolo,

Paolo Abeni <pabeni(a)redhat.com> 于2021年2月4日周四 上午1:24写道：
>
> On Wed, 2021-02-03 at 19:30 +0800, Geliang Tang wrote:
> > I added two test cases for signaling multi addresses today:
> >
> >          # signal addresses
> >          reset
> >          ip netns exec $ns1 ./pm_nl_ctl limits 3 3
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.3.1 flags signal
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.4.1 flags signal
> >          ip netns exec $ns2 ./pm_nl_ctl limits 3 3
> >          run_tests $ns1 $ns2 10.0.1.1
> >          chk_join_nr "signal addresses" 3 3 3
> >          chk_add_nr 3 3
> >
> >          # signal invalid addresses
> >          reset
> >          ip netns exec $ns1 ./pm_nl_ctl limits 3 3
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.12.1 flags signal
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.13.1 flags signal
> >          ip netns exec $ns1 ./pm_nl_ctl add 10.0.14.1 flags signal
> >          ip netns exec $ns2 ./pm_nl_ctl limits 3 3
> >          run_tests $ns1 $ns2 10.0.1.1
> >          chk_join_nr "signal invalid addresses" 0 0 0
> >          chk_add_nr 1 1
> >
> > The 1st one works well, the 2nd one added three invalid addresses, but
> > only got 1 ADD_ADDR and 1 ECHO. I thought it should be 0 ADD_ADDR or
> > 3 ADD_ADDRs.
> >
> > In the 2nd test case, mptcp_pm_create_subflow_or_signal_addr was only
> > triggered once when the msk is established. Since the first address is an
> > invalid one, the subflow for it cannot be created successfully. So
> > mptcp_pm_nl_subflow_established could not be invoked. The last two
> > addresses didn't have a chance to be announced. I think this behavior is
> > incorrect.
> >
> > I have several questions about this:
> >
> > 1. Is this an known issue? Is it worth creating a new issue on github and
> > fixing it?
>
> I think filing a github issue is the correct thing to do, so that we
> don't lose track of this in the ML.
>
> Even if I must admit it looks a low prio item to me.
>
> > 2. What do we expect for the 2nd test case, 0 ADD_ADDR or 3 ADD_ADDRs?
> > 3. Should we skip announcing the invalid addresses?
> > 4. Or should we change the logic of mptcp_pm_create_subflow_or_signal_addr
> > to announce all the invalid addresses?
>
> I think the "correct" behaviour would be announcing 3 addresses.
> Setting and maintaining correct list of addresses is up to the user-
> space/path-manger.
>
> The kernel could teorerically watch out for local IP address changes,
> but even announcing only IPs that are locally available would not
> guarantee the related subflow to be established - for a gazilion of
> reasons, last but not least the address could be removed by the admin
> after being announced and before subflow creation.
>
> Overall I think the kernel should not filter the addresses to be
> annonced in any way.
>
> Eventually we could change how add_addr events are scheduled, e.g.
> moving to the next address after that the previous one has been echoed
> by the peer.
>
> As I said I think it's not an huge priority, we have planty of bugs to
> fix first ;) So I would just keep the current result, possibly adding a
> TODO/FIXME note in the test and/or in the relevant kernel code.
>
> All the above IMHO.
>

Thanks for your suggestions. I had created issues #151 for this and
assigned it to myself. I'll try to fix it recently.

-Geliang

> Cheers,
>
> Paolo
>