declare one point for ofp version

src/openflow/ofp13/ofp_header.rs

@@ -6,6 +6,8 @@ use std::{
 
 use crate::openflow::ofp13::OpenflowHeader;
 
+use super::{OfpMsgEvent, Openflow13};
+
 pub struct OfpHeader {
     pub version: u8,
     pub message: u8,
@@ -16,14 +18,14 @@ pub struct OfpHeader {
 impl OpenflowHeader for OfpHeader {
     fn new(message: u8, length: usize, xid: usize) -> Self {
         Self {
-            version: 4,
+            version: Openflow13::ofp_version() as u8,
             message,
             length: (size_of::<OfpHeader>() + length) as u16,
             xid: xid as u32,
         }
     }
     fn version(&self) -> usize {
-        4
+        Openflow13::ofp_version()
     }
     fn message(&self) -> u8 {
         self.message

src/openflow/ofp13/ofp_manager.rs

@@ -35,10 +35,10 @@ impl OfpMsgEvent for Openflow13 {
         PacketOutEvent::new(port_id, payload, actions)
     }
     fn ofp_version() -> usize {
-        4
+        0x04
     }
     fn version(&self) -> usize {
-        4
+        Self::ofp_version()
     }
 
     fn header(&self, message: u8, length: u16, xid: u32) -> OfpHeader {