selftests: net: mptcp: add checks for fallback counters

Recently, some mib counters about fallback has been added, this patch
provides a method to check the expected behavior of these mib counters
during the test execution.

Link: multipath-tcp/mptcp_net-next#571
Signed-off-by: Gang Yan <[email protected]>

------
Changelog:
  v3:
    - Squash into a single patch.
    - Using 'fb_' as a prefix instead of the suffix for variables.
    - Adjust the order of mib counters to check, ensuring it matches the
      variable declaration.
    - The namespace('ns1'/'ns2') is included in the output of
      'chk_fallback_nr', like:
      "ns2 infinite map tx fallback        [IGNO] (flaky) got 1 infinite map tx fallback[s] in ns2 expected 0"
    - Add a new helper named 'chk_fallback_nr_all', which prints only
      when an error occurs.
    - Fix some code style issues.

  v2:
    - add a helper which can check all the fallback mib counters.
    - put the 'chk_fallback_nr' in 'chk_join_nr' like chk_join_tx_nr.

Notes:

Hi Matt,

I wanted to apologize for splitting the changes into multiple commits,
my intention was to ease the review process, but it unfortunately
backfired.

Thanks for your valuable suggestions, I've made some improvements based
on your feedback.

Please take another look at the updated changes.

Best regards,
Gang

Author: Dwyane-Yan

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -74,6 +74,17 @@ unset join_create_err
 unset join_bind_err
 unset join_connect_err
 
+unset fb_ns1
+unset fb_ns2
+unset fb_infinite_map_tx
+unset fb_dss_corruption
+unset fb_simult_conn
+unset fb_mpc_passive
+unset fb_mpc_active
+unset fb_mpc_data
+unset fb_md5_sig
+unset fb_dss
+
 # generated using "nfbpf_compile '(ip && (ip[54] & 0xf0) == 0x30) ||
 #				  (ip6 && (ip6[74] & 0xf0) == 0x30)'"
 CBPF_MPTCP_SUBOPTION_ADD_ADDR="14,
@@ -1399,6 +1410,115 @@ chk_join_tx_nr()
 	print_results "join Tx" ${rc}
 }
 
+chk_fallback_nr()
+{
+	local infinite_map_tx=${fb_infinite_map_tx:-0}
+	local dss_corruption=${fb_dss_corruption:-0}
+	local simult_conn=${fb_simult_conn:-0}
+	local mpc_passive=${fb_mpc_passive:-0}
+	local mpc_active=${fb_mpc_active:-0}
+	local mpc_data=${fb_mpc_data:-0}
+	local md5_sig=${fb_md5_sig:-0}
+	local dss=${fb_dss:-0}
+	local rc=${KSFT_PASS}
+	local ns=$1
+	local count
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtInfiniteMapTx")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$infinite_map_tx" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns infinite map tx fallback"
+		fail_test "got $count infinite map tx fallback[s] in $ns expected $infinite_map_tx"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtDSSCorruptionFallback")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$dss_corruption" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns dss corruption fallback"
+		fail_test "got $count dss corruption fallback[s] in $ns expected $dss_corruption"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtSimultConnectFallback")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$simult_conn" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns simult conn fallback"
+		fail_test "got $count simult conn fallback[s] in $ns expected $simult_conn"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtMPCapableFallbackACK")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$mpc_passive" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns mpc passive fallback"
+		fail_test "got $count mpc passive fallback[s] in $ns expected $mpc_passive"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtMPCapableFallbackSYNACK")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$mpc_active" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns mpc active fallback"
+		fail_test "got $count mpc active fallback[s] in $ns expected $mpc_active"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtMPCapableDataFallback")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$mpc_data" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns mpc data fallback"
+		fail_test "got $count mpc data fallback[s] in $ns expected $mpc_data"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtMD5SigFallback")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$md5_sig" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns MD5 Sig fallback"
+		fail_test "got $count MD5 Sig fallback[s] in $ns expected $MD5_Sig"
+	fi
+
+	count=$(mptcp_lib_get_counter ${!ns} "MPTcpExtDssFallback")
+	if [ -z "$count" ]; then
+		rc=${KSFT_SKIP}
+	elif [ "$count" != "$dss" ]; then
+		rc=${KSFT_FAIL}
+		print_check "$ns dss fallback"
+		fail_test "got $count dss fallback[s] in $ns expected $dss"
+	fi
+
+	return $rc
+}
+
+chk_fallback_nr_all()
+{
+	local netns=("ns1" "ns2")
+	local fb_ns=("fb_ns1" "fb_ns2")
+	local rc=${KSFT_PASS}
+
+	for i in 0 1; do
+		if [ -n "${!fb_ns[i]}" ]; then
+			eval "${!fb_ns[i]}" \
+				chk_fallback_nr ${netns[i]} || rc={?}
+		else
+			chk_fallback_nr ${netns[i]} || rc={?}
+		fi
+	done
+
+	if [ "$rc" != "${KSFT_PASS}" ]; then
+		print_results "fallback" $rc
+	fi
+}
+
 chk_join_nr()
 {
 	local syn_nr=$1
@@ -1484,6 +1604,8 @@ chk_join_nr()
 	join_syn_tx="${join_syn_tx:-${syn_nr}}" \
 		chk_join_tx_nr
 
+	chk_fallback_nr_all
+
 	if $validate_checksum; then
 		chk_csum_nr $csum_ns1 $csum_ns2
 		chk_fail_nr $fail_nr $fail_nr
@@ -3337,6 +3459,7 @@ fail_tests()
 		join_csum_ns1=+1 join_csum_ns2=+0 \
 			join_fail_nr=1 join_rst_nr=0 join_infi_nr=1 \
 			join_corrupted_pkts="$(pedit_action_pkts)" \
+			fb_ns1="fb_dss=1" fb_ns2="fb_infinite_map_tx=1" \
 			chk_join_nr 0 0 0
 		chk_fail_nr 1 -1 invert
 	fi