selftests/net: Add a test for TCP-AO keys matching

selftests/net: Add a test for TCP-AO keys matching

Add TCP-AO tests on connect()/accept() pair.
SNMP counters exposed by kernel are very useful here to verify the
expected behavior of TCP-AO.

Expected output for ipv4 version:
> # ./connect-deny_ipv4
> 1..19
> # 1702[lib/setup.c:254] rand seed 1680553689
> TAP version 13
> ok 1 Non-AO server + AO client
> ok 2 Non-AO server + AO client: counter TCPAOKeyNotFound increased 0 => 1
> ok 3 AO server + Non-AO client
> ok 4 AO server + Non-AO client: counter TCPAORequired increased 0 => 1
> ok 5 Wrong password
> ok 6 Wrong password: counter TCPAOBad increased 0 => 1
> ok 7 Wrong rcv id
> ok 8 Wrong rcv id: counter TCPAOKeyNotFound increased 1 => 2
> ok 9 Wrong snd id
> ok 10 Wrong snd id: counter TCPAOGood increased 0 => 1
> ok 11 Server: Wrong addr: counter TCPAOKeyNotFound increased 2 => 3
> ok 12 Server: Wrong addr
> ok 13 Client: Wrong addr: connect() was prevented
> ok 14 rcv id != snd id: connected
> ok 15 rcv id != snd id: counter TCPAOGood increased 1 => 3
> ok 16 Server: prefix match: connected
> ok 17 Server: prefix match: counter TCPAOGood increased 4 => 6
> ok 18 Client: prefix match: connected
> ok 19 Client: prefix match: counter TCPAOGood increased 7 => 9
> # Totals: pass:19 fail:0 xfail:0 xpass:0 skip:0 error:0

Expected output for ipv6 version:
> # ./connect-deny_ipv6
> 1..19
> # 1725[lib/setup.c:254] rand seed 1680553711
> TAP version 13
> ok 1 Non-AO server + AO client
> ok 2 Non-AO server + AO client: counter TCPAOKeyNotFound increased 0 => 1
> ok 3 AO server + Non-AO client: counter TCPAORequired increased 0 => 1
> ok 4 AO server + Non-AO client
> ok 5 Wrong password: counter TCPAOBad increased 0 => 1
> ok 6 Wrong password
> ok 7 Wrong rcv id: counter TCPAOKeyNotFound increased 1 => 2
> ok 8 Wrong rcv id
> ok 9 Wrong snd id: counter TCPAOGood increased 0 => 1
> ok 10 Wrong snd id
> ok 11 Server: Wrong addr
> ok 12 Server: Wrong addr: counter TCPAOKeyNotFound increased 2 => 3
> ok 13 Client: Wrong addr: connect() was prevented
> ok 14 rcv id != snd id: connected
> ok 15 rcv id != snd id: counter TCPAOGood increased 1 => 3
> ok 16 Server: prefix match: connected
> ok 17 Server: prefix match: counter TCPAOGood increased 5 => 7
> ok 18 Client: prefix match: connected
> ok 19 Client: prefix match: counter TCPAOGood increased 8 => 10
> # Totals: pass:19 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>