From 22c260ed9cdc96a5288934f543e946f494a0c811 Mon Sep 17 00:00:00 2001
From: Euan Rochester <euan@rochester.me.uk>
Date: Mon, 3 Jul 2017 18:47:36 +0100
Subject: [PATCH] Make Error an associated type of UdpCodec

---
 examples/udp-codec.rs |  1 +
 src/net/udp/frame.rs  | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/examples/udp-codec.rs b/examples/udp-codec.rs
index e7456f71..00663280 100644
--- a/examples/udp-codec.rs
+++ b/examples/udp-codec.rs
@@ -23,6 +23,7 @@ pub struct LineCodec;
 impl UdpCodec for LineCodec {
     type In = (SocketAddr, Vec<u8>);
     type Out = (SocketAddr, Vec<u8>);
+    type Error = io::Error;
 
     fn decode(&mut self, addr: &SocketAddr, buf: &[u8]) -> io::Result<Self::In> {
         Ok((*addr, buf.to_vec()))
diff --git a/src/net/udp/frame.rs b/src/net/udp/frame.rs
index 28705f95..c41acfb7 100644
--- a/src/net/udp/frame.rs
+++ b/src/net/udp/frame.rs
@@ -26,6 +26,19 @@ pub trait UdpCodec {
     /// The type of frames to be encoded.
     type Out;
 
+    /// The type of unrecoverable frame decoding errors.
+    ///
+    /// If an individual message is ill-formed but can be ignored without
+    /// interfering with the processing of future messages, it may be more
+    /// useful to report the failure as an `Item`.
+    ///
+    /// `From<io::Error>` is required in the interest of making `Error` suitable
+    /// for returning directly from a `Framed`.alloc
+    ///
+    /// Note that implementors of this trait can simply indicate `type Error =
+    /// io::Error` to use I/O errors as this type.
+    type Error: From<io::Error>;
+
     /// Attempts to decode a frame from the provided buffer of bytes.
     ///
     /// This method is called by `UdpFramed` on a single datagram which has been
@@ -37,7 +50,7 @@ pub trait UdpCodec {
     /// Finally, if the bytes in the buffer are malformed then an error is
     /// returned indicating why. This informs `Framed` that the stream is now
     /// corrupt and should be terminated.
-    fn decode(&mut self, src: &SocketAddr, buf: &[u8]) -> io::Result<Self::In>;
+    fn decode(&mut self, src: &SocketAddr, buf: &[u8]) -> Result<Self::In,Self::Error>;
 
     /// Encodes a frame into the buffer provided.
     ///
@@ -65,9 +78,9 @@ pub struct UdpFramed<C> {
 
 impl<C: UdpCodec> Stream for UdpFramed<C> {
     type Item = C::In;
-    type Error = io::Error;
+    type Error = C::Error;
 
-    fn poll(&mut self) -> Poll<Option<C::In>, io::Error> {
+    fn poll(&mut self) -> Poll<Option<C::In>, C::Error> {
         let (n, addr) = try_nb!(self.socket.recv_from(&mut self.rd));
         trace!("received {} bytes, decoding", n);
         let frame = try!(self.codec.decode(&addr, &self.rd[..n]));