Add tests which verify that the new helpers work for both IPv4 and
IPv6, by forcing SYN cookies to always on. Use a new network namespace
to avoid clobbering the global SYN cookie settings.
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>