selftests: mptcp: fail if not enough SYN/3rd ACK

If we receive less MPCapable SYN or 3rd ACK than expected, we now mark
the test as failed.

On the other hand, if we receive more, we keep the warning but we add a
hint that it is probably due to retransmissions and that's why we don't
mark the test as failed.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/148Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -483,10 +483,6 @@ do_transfer()
 	check_transfer $cin $sout "file received by server"
 	rets=$?
 
-	if [ $retc -eq 0 ] && [ $rets -eq 0 ]; then
-		printf "[ OK ]"
-	fi
-
 	local stat_synrx_now_l=$(get_mib_counter "${listener_ns}" "MPTcpExtMPCapableSYNRX")
 	local stat_ackrx_now_l=$(get_mib_counter "${listener_ns}" "MPTcpExtMPCapableACKRX")
 	local stat_cookietx_now=$(get_mib_counter "${listener_ns}" "TcpExtSyncookiesSent")
@@ -502,6 +498,22 @@ do_transfer()
 		expect_synrx=$((stat_synrx_last_l+1))
 		expect_ackrx=$((stat_ackrx_last_l+1))
 	fi
+
+	if [ ${stat_synrx_now_l} -lt ${expect_synrx} ]; then
+		printf "[ FAIL ] lower MPC SYN rx (%d) than expected (%d)\n" \
+			"${stat_synrx_now_l}" "${expect_synrx}" 1>&2
+		retc=1
+	fi
+	if [ ${stat_ackrx_now_l} -lt ${expect_ackrx} ]; then
+		printf "[ FAIL ] lower MPC ACK rx (%d) than expected (%d)\n" \
+			"${stat_ackrx_now_l}" "${expect_ackrx}" 1>&2
+		rets=1
+	fi
+
+	if [ $retc -eq 0 ] && [ $rets -eq 0 ]; then
+		printf "[ OK ]"
+	fi
+
 	if [ $cookies -eq 2 ];then
 		if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
 			printf " WARN: CookieSent: did not advance"
@@ -518,12 +530,12 @@ do_transfer()
 		fi
 	fi
 
-	if [ $expect_synrx -ne $stat_synrx_now_l ] ;then
-		printf " WARN: SYNRX: expect %d, got %d" \
+	if [ ${stat_synrx_now_l} -gt ${expect_synrx} ]; then
+		printf " WARN: SYNRX: expect %d, got %d (probably retransmissions)" \
 			"${expect_synrx}" "${stat_synrx_now_l}"
 	fi
-	if [ $expect_ackrx -ne $stat_ackrx_now_l ] ;then
-		printf " WARN: ACKRX: expect %d, got %d" \
+	if [ ${stat_ackrx_now_l} -gt ${expect_ackrx} ]; then
+		printf " WARN: ACKRX: expect %d, got %d (probably retransmissions)" \
 			"${expect_ackrx}" "${stat_ackrx_now_l}"
 	fi