net: selftest: add test for netdev netlink queue-get API

Add a selftest for netdev generic netlink. For now there is only a
single test that exercises the `queue-get` API.

The test works with netdevsim by default or with a real device by
setting NETIF.

Add a timeout param to cmd() since ethtool -L can take a long time on
real devices.

Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/20240507163228.2066817-3-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: py: check process exit code in bkg() and background cmd()

We're a bit too loose with error checking for background
processes. cmd() completely ignores the fail argument
passed to the constructor if background is True.
Default to checking for errors if process is not terminated
explicitly. Caller can override with True / False.

For bkg() the processing step is called magically by __exit__
so record the value passed in the constructor.

Reported-by: Willem de Bruijn <willemb@google.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240502025325.1924923-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: py: avoid all ports < 10k

When picking TCP ports to use, avoid all below 10k.
This should lower the chance of collision or running
afoul whatever random policies may be on the host.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240429144426.743476-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: py: extract tool logic

The main use of the ip() wrapper over cmd() is that it can parse JSON.
cmd("ip -j link show") will return stdout as a string, and test has
to call json.loads(). With ip("link show", json=True) the return value
will be already parsed.

More tools (ethtool, bpftool etc.) support the --json switch.
To avoid having to wrap all of them individually create a tool()
helper.

Switch from -j to --json (for ethtool).
While at it consume the netns attribute at the ip() level.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240429144426.743476-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: drv-net: add a TCP ping test case (and useful helpers)

More complex tests often have to spawn a background process,
like a server which will respond to requests or tcpdump.

Add support for creating such processes using the with keyword:

with bkg("my-daemon", ..):
# my-daemon is alive in this block

My initial thought was to add this support to cmd() directly
but it runs the command in the constructor, so by the time
we __enter__ it's too late to make sure we used "background=True".

Second useful helper transplanted from net_helper.sh is
wait_port_listen().

The test itself uses socat, which insists on v6 addresses
being wrapped in [], it's not the only command which requires
this format, so add the wrapped address to env. The hope
is to save test code from checking if address is v6.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240420025237.3309296-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: drv-net: define endpoint structures

Define the remote endpoint "model". To execute most meaningful device
driver tests we need to be able to communicate with a remote system,
and have it send traffic to the device under test.

Various test environments will have different requirements.

0) "Local" netdevsim-based testing can simply use net namespaces.
netdevsim supports connecting two devices now, to form a veth-like
construct.

1) Similarly on hosts with multiple NICs, the NICs may be connected
together with a loopback cable or internal device loopback.
One interface may be placed into separate netns, and tests
would proceed much like in the netdevsim case. Note that
the loopback config or the moving of one interface
into a netns is not expected to be part of selftest code.

2) Some systems may need to communicate with the remote endpoint
via SSH.

3) Last but not least environment may have its own custom communication
method.

Fundamentally we only need two operations:
- run a command remotely
- deploy a binary (if some tool we need is built as part of kselftests)

Wrap these two in a class. Use dynamic loading to load the Remote
class. This will allow very easy definition of other communication
methods without bothering upstream code base.

Stick to the "simple" / "no unnecessary abstractions" model for
referring to the remote endpoints. The host / remote object are
passed as an argument to the usual cmd() or ip() invocation.
For example:

ip("link show", json=True, host=remote)

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240420025237.3309296-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: drv-net: add stdout to the command failed exception

ping prints all the info to stdout. To make debug easier capture
stdout in the Exception raised when command unexpectedly fails.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240416004556.1618804-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: add scaffolding for Netlink tests in Python

Add glue code for accessing the YNL library which lives under
tools/net and YAML spec files from under Documentation/.
Automatically figure out if tests are run in tree or not.
Since we'll want to use this library both from net and
drivers/net test targets make the library a target as well,
and automatically include it when net or drivers/net are
included. Making net/lib a target ensures that we end up
with only one copy of it, and saves us some path guessing.

Add a tiny bit of formatting support to be able to output KTAP
from the start.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>