selftests/net: Verify that TCP-AO complies with ignoring ICMPs

Hand-crafted ICMP packets are sent to the server, the server checks for
hard/soft errors and fails if any.

Expected output for ipv4 version:
> # ./icmps-discard_ipv4
> 1..3
> # 3164[lib/setup.c:166] rand seed 1642623745
> TAP version 13
> # 3164[lib/proc.c:207]    Snmp6             Ip6InReceives: 0 => 1
> # 3164[lib/proc.c:207]    Snmp6             Ip6InNoRoutes: 0 => 1
> # 3164[lib/proc.c:207]    Snmp6               Ip6InOctets: 0 => 76
> # 3164[lib/proc.c:207]    Snmp6            Ip6InNoECTPkts: 0 => 1
> # 3164[lib/proc.c:207]      Tcp                    InSegs: 2 => 203
> # 3164[lib/proc.c:207]      Tcp                   OutSegs: 1 => 202
> # 3164[lib/proc.c:207]  IcmpMsg                   InType3: 0 => 543
> # 3164[lib/proc.c:207]     Icmp                    InMsgs: 0 => 543
> # 3164[lib/proc.c:207]     Icmp            InDestUnreachs: 0 => 543
> # 3164[lib/proc.c:207]       Ip                InReceives: 2 => 746
> # 3164[lib/proc.c:207]       Ip                InDelivers: 2 => 746
> # 3164[lib/proc.c:207]       Ip               OutRequests: 1 => 202
> # 3164[lib/proc.c:207]    IpExt                  InOctets: 132 => 61684
> # 3164[lib/proc.c:207]    IpExt                 OutOctets: 68 => 31324
> # 3164[lib/proc.c:207]    IpExt               InNoECTPkts: 2 => 744
> # 3164[lib/proc.c:207]   TcpExt               TCPPureAcks: 1 => 2
> # 3164[lib/proc.c:207]   TcpExt           TCPOrigDataSent: 0 => 200
> # 3164[lib/proc.c:207]   TcpExt              TCPDelivered: 0 => 199
> # 3164[lib/proc.c:207]   TcpExt                 TCPAOGood: 2 => 203
> # 3164[lib/proc.c:207]   TcpExt         TCPAODroppedIcmps: 0 => 541
> ok 1 InDestUnreachs delivered 543
> ok 2 Server survived 20000 bytes of traffic
> ok 3 ICMPs ignored 541
> # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0

Expected output for ipv6 version:
> # ./icmps-discard_ipv6
> 1..3
> # 3186[lib/setup.c:166] rand seed 1642623803
> TAP version 13
> # 3186[lib/proc.c:207]    Snmp6             Ip6InReceives: 4 => 568
> # 3186[lib/proc.c:207]    Snmp6             Ip6InDelivers: 3 => 564
> # 3186[lib/proc.c:207]    Snmp6            Ip6OutRequests: 2 => 204
> # 3186[lib/proc.c:207]    Snmp6            Ip6InMcastPkts: 1 => 4
> # 3186[lib/proc.c:207]    Snmp6           Ip6OutMcastPkts: 0 => 1
> # 3186[lib/proc.c:207]    Snmp6               Ip6InOctets: 320 => 70420
> # 3186[lib/proc.c:207]    Snmp6              Ip6OutOctets: 160 => 35512
> # 3186[lib/proc.c:207]    Snmp6          Ip6InMcastOctets: 72 => 336
> # 3186[lib/proc.c:207]    Snmp6         Ip6OutMcastOctets: 0 => 76
> # 3186[lib/proc.c:207]    Snmp6            Ip6InNoECTPkts: 4 => 568
> # 3186[lib/proc.c:207]    Snmp6               Icmp6InMsgs: 1 => 361
> # 3186[lib/proc.c:207]    Snmp6              Icmp6OutMsgs: 1 => 2
> # 3186[lib/proc.c:207]    Snmp6       Icmp6InDestUnreachs: 0 => 360
> # 3186[lib/proc.c:207]    Snmp6      Icmp6OutMLDv2Reports: 0 => 1
> # 3186[lib/proc.c:207]    Snmp6              Icmp6InType1: 0 => 360
> # 3186[lib/proc.c:207]    Snmp6           Icmp6OutType143: 0 => 1
> # 3186[lib/proc.c:207]      Tcp                    InSegs: 2 => 203
> # 3186[lib/proc.c:207]      Tcp                   OutSegs: 1 => 202
> # 3186[lib/proc.c:207]   TcpExt               TCPPureAcks: 1 => 2
> # 3186[lib/proc.c:207]   TcpExt           TCPOrigDataSent: 0 => 200
> # 3186[lib/proc.c:207]   TcpExt              TCPDelivered: 0 => 199
> # 3186[lib/proc.c:207]   TcpExt                 TCPAOGood: 2 => 203
> # 3186[lib/proc.c:207]   TcpExt         TCPAODroppedIcmps: 0 => 360
> ok 1 Icmp6InDestUnreachs delivered 360
> ok 2 Server survived 20000 bytes of traffic
> ok 3 ICMPs ignored 360
> # Totals: pass:3 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>

tools/testing/selftests/net/tcp_ao/Makefile

 # SPDX-License-Identifier: GPL-2.0
 TEST_BOTH_AF := connect
+TEST_BOTH_AF += icmps-discard
 
 TEST_IPV4_PROGS := $(TEST_BOTH_AF:%=%_ipv4)
 TEST_IPV6_PROGS := $(TEST_BOTH_AF:%=%_ipv6)