Fix ipd

schemes/ipd/src/interface/loopback.rs

@@ -22,10 +22,6 @@ impl Interface for LoopbackInterface {
         self.ip
     }
 
-    fn arp_event(&mut self) -> Result<()> {
-        Ok(())
-    }
-
     fn recv(&mut self) -> Result<Vec<Ipv4>> {
         let mut ips = Vec::new();
 
@@ -41,4 +37,12 @@ impl Interface for LoopbackInterface {
 
         Ok(0)
     }
+
+    fn arp_event(&mut self) -> Result<()> {
+        Ok(())
+    }
+
+    fn has_loopback_data(&self) -> bool {
+        ! self.packets.is_empty()
+    }
 }

schemes/ipd/src/interface/mod.rs

@@ -9,7 +9,10 @@ mod loopback;
 
 pub trait Interface {
     fn ip(&self) -> Ipv4Addr;
-    fn arp_event(&mut self) -> Result<()>;
     fn recv(&mut self) -> Result<Vec<Ipv4>>;
     fn send(&mut self, ip: Ipv4) -> Result<usize>;
+
+    fn arp_event(&mut self) -> Result<()>;
+
+    fn has_loopback_data(&self) -> bool { false }
 }