openflow/multipart: Add support NXST_FLOW_MONITOR

lib/openflow/enum_gen.ex

@@ -990,6 +990,14 @@ defmodule Openflow.EnumGen do
       apply_setfield_miss: 15,
       experimenter: 0xFFFE,
       experimenter_miss: 0xFFFF
+    ],
+    nx_flow_monitor_flags: [
+      initial: 1 <<< 0,
+      add: 1 <<< 1,
+      delete: 1 <<< 2,
+      modify: 1 <<< 3,
+      action: 1 <<< 4,
+      own: 1 <<< 5
     ]
   ]
 

lib/openflow/multipart/flow_monitor/request.ex

@@ -0,0 +1,23 @@
+defmodule Openflow.Multipart.FlowMonitor.Request do
+  defstruct(
+    version: 4,
+    xid: 0,
+    # virtual field
+    datapath_id: nil,
+    id: 0,
+    flags: [],
+    out_port: :none,
+    table_id: :all,
+    match: []
+  )
+
+  alias __MODULE__
+
+  def new(%Request{}) do
+    <<>>
+  end
+
+  def read(_binary) do
+    %Request{}
+  end
+end