selftests: forwarding: Parametrize mausezahn delay

The various multipath tests use mausezahn to generate different flows
and check how they are distributed between the available nexthops. The
tool is currently invoked with an hard coded transmission delay of 1 ms.
This is unnecessary when the tests are run with veth pairs and
needlessly prolongs the tests.

Parametrize this delay and default it to 0 us. It can be overridden
using the forwarding.config file. On my system, this reduces the run
time of router_multipath.sh by 93%.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20240304095612.462900-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: forwarding: Fix failing tests with old libnet

The custom multipath hash tests use mausezahn in order to test how
changes in various packet fields affect the packet distribution across
the available nexthops.

The tool uses the libnet library for various low-level packet
construction and injection. The library started using the
"SO_BINDTODEVICE" socket option for IPv6 sockets in version 1.1.6 and
for IPv4 sockets in version 1.2.

When the option is not set, packets are not routed according to the
table associated with the VRF master device and tests fail.

Fix this by prefixing the command with "ip vrf exec", which will cause
the route lookup to occur in the VRF routing table. This makes the tests
pass regardless of the libnet library version.

Fixes: 511e8db54036 ("selftests: forwarding: Add test for custom multipath hash")
Fixes: 185b0c190bb6 ("selftests: forwarding: Add test for custom multipath hash with IPv4 GRE")
Fixes: b7715acba4d3 ("selftests: forwarding: Add test for custom multipath hash with IPv6 GRE")
Reported-by: Ivan Vecera <ivecera@redhat.com>
Tested-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Link: https://lore.kernel.org/r/20220809113320.751413-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: forwarding: Add test for custom multipath hash

Test that when the hash policy is set to custom, traffic is distributed
only according to the outer fields set in the fib_multipath_hash_fields
sysctl.

Each time set a different field and make sure traffic is only
distributed when the field is changed in the packet stream.

The test only verifies the behavior with non-encapsulated IPv4 and IPv6
packets. Subsequent patches will add tests for IPv4/IPv6 overlays on top
of IPv4/IPv6 underlay networks.

Example output:

# ./custom_multipath_hash.sh
TEST: ping [ OK ]
TEST: ping6 [ OK ]
INFO: Running IPv4 custom multipath hash tests
TEST: Multipath hash field: Source IP (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 6353 / 6254
TEST: Multipath hash field: Source IP (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 0 / 12600
TEST: Multipath hash field: Destination IP (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 6102 / 6502
TEST: Multipath hash field: Destination IP (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 1 / 12601
TEST: Multipath hash field: Source port (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 16428 / 16345
TEST: Multipath hash field: Source port (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 32770 / 2
TEST: Multipath hash field: Destination port (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 16428 / 16345
TEST: Multipath hash field: Destination port (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 32770 / 2
INFO: Running IPv6 custom multipath hash tests
TEST: Multipath hash field: Source IP (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 6704 / 5903
TEST: Multipath hash field: Source IP (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 12600 / 0
TEST: Multipath hash field: Destination IP (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 5551 / 7052
TEST: Multipath hash field: Destination IP (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 12603 / 0
TEST: Multipath hash field: Flowlabel (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 8378 / 8080
TEST: Multipath hash field: Flowlabel (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 2 / 12603
TEST: Multipath hash field: Source port (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 16385 / 16388
TEST: Multipath hash field: Source port (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 0 / 32774
TEST: Multipath hash field: Destination port (balanced) [ OK ]
INFO: Packets sent on path1 / path2: 16386 / 16390
TEST: Multipath hash field: Destination port (unbalanced) [ OK ]
INFO: Packets sent on path1 / path2: 32771 / 2

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>