associate mtu with the capacity of ReadBuf for all platforms

src/async/device.rs

@@ -50,11 +50,12 @@ impl AsyncDevice {
     }
 
     /// Consumes this AsyncDevice and return a Framed object (unified Stream and Sink interface)
-    pub fn into_framed(mut self) -> Framed<Self, TunPacketCodec> {
-        let packet_information = self.get_mut().has_packet_information();
+    pub fn into_framed(self) -> Framed<Self, TunPacketCodec> {
+        let packet_information = self.get_ref().has_packet_information();
         let mtu = self.inner.get_ref().mtu().unwrap_or(1504);
         let codec = TunPacketCodec::new(packet_information, mtu);
-        Framed::new(self, codec)
+        // associate mtu with the capacity of ReadBuf
+        Framed::with_capacity(self, codec, mtu as usize)
     }
 }
 

src/platform/linux/device.rs

@@ -161,7 +161,7 @@ impl Device {
     }
 
     /// Return whether the device has packet information
-    pub fn has_packet_information(&mut self) -> bool {
+    pub fn has_packet_information(&self) -> bool {
         self.queues[0].has_packet_information()
     }
 
@@ -405,7 +405,7 @@ pub struct Queue {
 }
 
 impl Queue {
-    pub fn has_packet_information(&mut self) -> bool {
+    pub fn has_packet_information(&self) -> bool {
         self.packet_information
     }