Re: [PATCH net-next 1/3] selftests: drv-net: resolve remote interface name

Petr Machata
2025-02-13T14:39:21Z

Jakub Kicinski <kuba@kernel.org> writes:

> Find out and record in env the name of the interface which remote host
> will use for the IP address provided via config.
>
> Interface name is useful for mausezahn and for setting up tunnels.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> tools/testing/selftests/drivers/net/lib/py/env.py | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/tools/testing/selftests/drivers/net/lib/py/env.py b/tools/testing/selftests/drivers/net/lib/py/env.py
> index 886b4904613c..fc649797230b 100644
> --- a/tools/testing/selftests/drivers/net/lib/py/env.py
> +++ b/tools/testing/selftests/drivers/net/lib/py/env.py
> @@ -154,6 +154,9 @@ from .remote import Remote
> self.ifname = self.dev['ifname']
> self.ifindex = self.dev['ifindex']
>
> + # resolve remote interface name
> + self.remote_ifname = self.resolve_remote_ifc()
> +
> self._required_cmd = {}
>
> def create_local(self):
> @@ -200,6 +203,16 @@ from .remote import Remote
> raise Exception("Invalid environment, missing configuration:", missing,
> "Please see tools/testing/selftests/drivers/net/README.rst")
>
> + def resolve_remote_ifc(self):
> + v4 = v6 = None
> + if self.remote_v4:
> + v4 = ip("addr show to " + self.remote_v4, json=True, host=self.remote)
> + if self.remote_v6:
> + v6 = ip("addr show to " + self.remote_v6, json=True, host=self.remote)
> + if v4 and v6 and v4[0]["ifname"] != v6[0]["ifname"]:
> + raise Exception("Can't resolve remote interface name, v4 and v6 don't match")
> + return v6[0]["ifname"] if v6 else v4[0]["ifname"]

Is existence of more than one interface with the same IP address a
concern? I guess such configuration is broken and wouldn't come up in a
selftest, but consider throwing in an "len(v4) == len(v6) == 1" for
robustness sake. I guess it could in fact replace the "v4 and v6" bit.

> +
> def __enter__(self):
> return self