selftests: mptcp: add test-cases for mixed v4/v6 subflows

Note that we can't guess the listener family anymore based on the client
target address: always use IPv6.

The fullmesh flag with endpoints from different families is also
validated here.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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

@@ -774,24 +774,17 @@ do_transfer()
 		addr_nr_ns2=${addr_nr_ns2:9}
 	fi
 
-	local local_addr
-	if is_v6 "${connect_addr}"; then
-		local_addr="::"
-	else
-		local_addr="0.0.0.0"
-	fi
-
 	extra_srv_args="$extra_args $extra_srv_args"
 	if [ "$test_link_fail" -gt 1 ];then
 		timeout ${timeout_test} \
 			ip netns exec ${listener_ns} \
 				./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-					$extra_srv_args ${local_addr} < "$sinfail" > "$sout" &
+					$extra_srv_args "::" < "$sinfail" > "$sout" &
 	else
 		timeout ${timeout_test} \
 			ip netns exec ${listener_ns} \
 				./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-					$extra_srv_args ${local_addr} < "$sin" > "$sout" &
+					$extra_srv_args "::" < "$sin" > "$sout" &
 	fi
 	local spid=$!
 
@@ -2448,6 +2441,47 @@ v4mapped_tests()
 	fi
 }
 
+mixed_tests()
+{
+	if reset "IPv4 sockets do not use IPv6 addresses"; then
+		pm_nl_set_limits $ns1 0 1
+		pm_nl_set_limits $ns2 1 1
+		pm_nl_add_endpoint $ns1 dead:beef:2::1 flags signal
+		run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+		chk_join_nr 0 0 0
+	fi
+
+	# Need an IPv6 mptcp socket to allow subflows of both families
+	if reset "simult IPv4 and IPv6 subflows"; then
+		pm_nl_set_limits $ns1 0 1
+		pm_nl_set_limits $ns2 1 1
+		pm_nl_add_endpoint $ns1 10.0.1.1 flags signal
+		run_tests $ns1 $ns2 dead:beef:2::1 0 0 0 slow
+		chk_join_nr 1 1 1
+	fi
+
+	# cross families subflows will not be created even in fullmesh mode
+	if reset "simult IPv4 and IPv6 subflows, fullmesh 1x1"; then
+		pm_nl_set_limits $ns1 0 4
+		pm_nl_set_limits $ns2 1 4
+		pm_nl_add_endpoint $ns2 dead:beef:2::2 flags subflow,fullmesh
+		pm_nl_add_endpoint $ns1 10.0.1.1 flags signal
+		run_tests $ns1 $ns2 dead:beef:2::1 0 0 0 slow
+		chk_join_nr 1 1 1
+	fi
+
+	# fullmesh still tries to create all the possibly subflows with
+	# matching family
+	if reset "simult IPv4 and IPv6 subflows, fullmesh 2x2"; then
+		pm_nl_set_limits $ns1 0 4
+		pm_nl_set_limits $ns2 2 4
+		pm_nl_add_endpoint $ns1 10.0.2.1 flags signal
+		pm_nl_add_endpoint $ns1 dead:beef:2::1 flags signal
+		run_tests $ns1 $ns2 dead:beef:1::1 0 0 fullmesh_1 slow
+		chk_join_nr 4 4 4
+	fi
+}
+
 backup_tests()
 {
 	# single subflow, backup
@@ -3120,6 +3154,7 @@ all_tests_sorted=(
 	a@add_tests
 	6@ipv6_tests
 	4@v4mapped_tests
+	M@mixed_tests
 	b@backup_tests
 	p@add_addr_ports_tests
 	k@syncookies_tests