selftests: mptcp: dump more info on errors

Even if that may sound completely unlikely, the mptcp implementation
is not perfect, yet.

When the self-tests report an error we usually need more information
of what the scripts currently report. iproute allow provides
some additional goodies since a few releases, let's dump them.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -128,6 +128,7 @@ cleanup()
 	local netns
 	for netns in "$ns1" "$ns2" "$ns3" "$ns4";do
 		ip netns del $netns
+		rm -f /tmp/$netns.{nstat,out}
 	done
 }
 
@@ -438,16 +439,24 @@ do_transfer()
 		kill ${cappid_connector}
 	fi
 
+	NSTAT_HISTORY=/tmp/${listener_ns}.nstat ip netns exec ${listener_ns} \
+		nstat | grep Tcp > /tmp/${listener_ns}.out
+	if [ ${listener_ns} != ${connector_ns} ]; then
+		NSTAT_HISTORY=/tmp/${connector_ns}.nstat ip netns exec ${connector_ns} \
+			nstat | grep Tcp > /tmp/${connector_ns}.out
+	fi
+
 	local duration
 	duration=$((stop-start))
 	duration=$(printf "(duration %05sms)" $duration)
 	if [ ${rets} -ne 0 ] || [ ${retc} -ne 0 ]; then
 		echo "$duration [ FAIL ] client exit code $retc, server $rets" 1>&2
 		echo -e "\nnetns ${listener_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${listener_ns} ss -nita 1>&2 -o "sport = :$port"
+		ip netns exec ${listener_ns} ss -Menita 1>&2 -o "sport = :$port"
+		cat /tmp/${listener_ns}.out
 		echo -e "\nnetns ${connector_ns} socket stat for ${port}:" 1>&2
-		ip netns exec ${connector_ns} ss -nita 1>&2 -o "dport = :$port"
-
+		ip netns exec ${connector_ns} ss -Menita 1>&2 -o "dport = :$port"
+		[ ${listener_ns} != ${connector_ns} ] && cat /tmp/${connector_ns}.out
 		cat "$capout"
 		return 1
 	fi