feat: added tcp

sorry Judah

nl-sys/src/nl_ffi.rs

@@ -92,6 +92,7 @@ extern "C" {
     pub fn rtnl_link_get_name(link: *mut rtnl_link) -> *const c_char;
     pub fn rtnl_link_get_ifindex(link: *mut rtnl_link) -> c_int;
     pub fn rtnl_link_get_type(link: *mut rtnl_link) -> *const c_char;
+    pub fn rtnl_link_get_mtu(link: *mut rtnl_link) -> c_uint;
 
     pub fn rtnl_route_alloc_cache(
         sock: *mut nl_sock,

nl-sys/src/route.rs

@@ -91,6 +91,11 @@ impl Link {
         }
     }
 
+    /// Returns the MTU of the link
+    pub fn mtu(&self) -> u32 {
+        unsafe { rtnl_link_get_mtu(self.link) }
+    }
+
     /// Determines the type of link. Ethernet devices are "veth or eth"
     pub fn ltype(&self) -> Option<String> {
         unsafe {