Refactor errors (#46)

This patch does a bunch of refactoring, mostly around error types, but it also
paves the way to allow `Codec` to be used standalone.

* `Codec` (and `FramedRead` / `FramedWrite`) is broken out into a codec module.
* An h2-codec crate is created that re-exports the frame and codec modules.
* New error types are introduced in the internals:
  * `RecvError` represents errors caused by trying to receive a frame.
  * `SendError` represents errors caused by trying to send a frame.
  * `UserError` is an enum of potential errors caused by invalid usage
    by the user of the lib.
  * `ProtoError` is either a `Reason` or an `io::Error`. However it doesn't
    specify connection or stream level.
  * `h2::Error` is an opaque error type and is the only error type exposed
    by the public API (used to be `ConnectionError`).

There are misc code changes to enable this as well. The biggest is a new "sink"
API for `Codec`. It provides buffer which queues up a frame followed by flush
which writes everything that is queued. This departs from the `Sink` trait in
order to provide more accurate error values. For example, buffer can never fail
(but it will panic if `poll_ready` is not called first).

Cargo.toml

@@ -8,7 +8,7 @@ futures = "0.1"
 tokio-io = "0.1.3"
 tokio-timer = "0.1"
 bytes = "0.4"
-http = { git = "https://github.com/carllerche/http", branch = "lower-case-header-name-parsing" }
+http = { git = "https://github.com/carllerche/http", rev = "2dd15d9" }
 byteorder = "1.0"
 log = "0.3.8"
 fnv = "1.0.5"

examples/client.rs

@@ -24,9 +24,9 @@ struct Process {
 
 impl Future for Process {
     type Item = ();
-    type Error = ConnectionError;
+    type Error = h2::Error;
 
-    fn poll(&mut self) -> Poll<(), ConnectionError> {
+    fn poll(&mut self) -> Poll<(), h2::Error> {
         loop {
             if self.trailers {
                 let trailers = try_ready!(self.body.poll_trailers());
@@ -71,7 +71,7 @@ pub fn main() {
             .uri("https://http2.akamai.com/")
             .body(()).unwrap();
 
-        let mut trailers = h2::HeaderMap::new();
+        let mut trailers = HeaderMap::new();
         trailers.insert("zomg", "hello".parse().unwrap());
 
         let mut stream = client.request(request, false).unwrap();

src/client.rs

@@ -1,9 +1,9 @@
-use {frame, HeaderMap, ConnectionError};
+use frame::{StreamId, Headers, Pseudo, Settings};
-use frame::StreamId;
+use frame::Reason::*;
-use proto::{self, Connection, WindowSize, ProtoError};
+use codec::{Codec, RecvError};
-use error::Reason::*;
+use proto::{self, Connection, WindowSize};
 
-use http::{Request, Response};
+use http::{Request, Response, HeaderMap};
 use futures::{Future, Poll, Sink, Async, AsyncSink, AndThen, MapErr};
 use tokio_io::{AsyncRead, AsyncWrite};
 use tokio_io::io::WriteAll;
@@ -16,9 +16,9 @@ use std::io::Error as IoError;
 pub struct Handshake<T: AsyncRead + AsyncWrite, B: IntoBuf = Bytes> {
     inner:
         AndThen<
-            MapErr<WriteAll<T, &'static [u8]>, fn(IoError) -> ConnectionError>,
+            MapErr<WriteAll<T, &'static [u8]>, fn(IoError) -> ::Error>,
-            Result<Client<T, B>, ConnectionError>,
+            Result<Client<T, B>, ::Error>,
-            fn((T, &'static [u8])) -> Result<Client<T, B>, ConnectionError>
+            fn((T, &'static [u8])) -> Result<Client<T, B>, ::Error>
         >
 
 }
@@ -63,28 +63,31 @@ impl<T, B> Client<T, B>
         debug!("binding client connection");
 
         let bind: fn((T, &'static [u8]))
-                    -> Result<Client<T, B>, ConnectionError> =
+                    -> Result<Client<T, B>, ::Error> =
             |(io, _)| {
                 debug!("client connection bound");
 
-                let mut framed_write = proto::framed_write(io);
+                // Create the codec
-                let settings = frame::Settings::default();
+                let mut codec = Codec::new(io);
+
+                // Create the initial SETTINGS frame
+                let settings = Settings::default();
 
                 // Send initial settings frame
-                match framed_write.start_send(settings.into()) {
+                match codec.start_send(settings.into()) {
                     Ok(AsyncSink::Ready) => {
-                        let connection = proto::from_framed_write(framed_write);
+                        let connection = Connection::new(codec);
                         Ok(Client { connection })
                     }
                     Ok(_) => unreachable!(),
-                    Err(e) => Err(ConnectionError::from(e)),
+                    Err(e) => Err(::Error::from(e)),
                 }
             };
 
         let msg: &'static [u8] =  b"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n";
         let handshake = io::write_all(io, msg)
-            .map_err(ConnectionError::from as
+            .map_err(::Error::from as
-                fn(IoError) -> ConnectionError
+                fn(IoError) -> ::Error
             )
             .and_then(bind);
 
@@ -93,15 +96,16 @@ impl<T, B> Client<T, B>
 
     /// Returns `Ready` when the connection can initialize a new HTTP 2.0
     /// stream.
-    pub fn poll_ready(&mut self) -> Poll<(), ConnectionError> {
+    pub fn poll_ready(&mut self) -> Poll<(), ::Error> {
-        self.connection.poll_send_request_ready()
+        Ok(self.connection.poll_send_request_ready())
     }
 
     /// Send a request on a new HTTP 2.0 stream
     pub fn request(&mut self, request: Request<()>, end_of_stream: bool)
-        -> Result<Stream<B>, ConnectionError>
+        -> Result<Stream<B>, ::Error>
     {
         self.connection.send_request(request, end_of_stream)
+            .map_err(Into::into)
             .map(|stream| Stream {
                 inner: stream,
             })
@@ -114,10 +118,11 @@ impl<T, B> Future for Client<T, B>
           B: IntoBuf,
 {
     type Item = ();
-    type Error = ConnectionError;
+    type Error = ::Error;
 
-    fn poll(&mut self) -> Poll<(), ConnectionError> {
+    fn poll(&mut self) -> Poll<(), ::Error> {
         self.connection.poll()
+            .map_err(Into::into)
     }
 }
 
@@ -139,7 +144,7 @@ impl<T, B> fmt::Debug for Client<T, B>
 impl<T, B: IntoBuf> Future for Handshake<T, B>
 where T: AsyncRead + AsyncWrite {
     type Item = Client<T, B>;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         self.inner.poll()
@@ -161,7 +166,7 @@ impl<T, B> fmt::Debug for Handshake<T, B>
 
 impl<B: IntoBuf> Stream<B> {
     /// Receive the HTTP/2.0 response, if it is ready.
-    pub fn poll_response(&mut self) -> Poll<Response<Body<B>>, ConnectionError> {
+    pub fn poll_response(&mut self) -> Poll<Response<Body<B>>, ::Error> {
         let (parts, _) = try_ready!(self.inner.poll_response()).into_parts();
         let body = Body { inner: self.inner.clone() };
 
@@ -180,29 +185,31 @@ impl<B: IntoBuf> Stream<B> {
     }
 
     /// Request to be notified when the stream's capacity increases
-    pub fn poll_capacity(&mut self) -> Poll<Option<usize>, ConnectionError> {
+    pub fn poll_capacity(&mut self) -> Poll<Option<usize>, ::Error> {
         let res = try_ready!(self.inner.poll_capacity());
         Ok(Async::Ready(res.map(|v| v as usize)))
     }
 
     /// Send data
     pub fn send_data(&mut self, data: B, end_of_stream: bool)
-        -> Result<(), ConnectionError>
+        -> Result<(), ::Error>
     {
         self.inner.send_data(data.into_buf(), end_of_stream)
+            .map_err(Into::into)
     }
 
     /// Send trailers
     pub fn send_trailers(&mut self, trailers: HeaderMap)
-        -> Result<(), ConnectionError>
+        -> Result<(), ::Error>
     {
         self.inner.send_trailers(trailers)
+            .map_err(Into::into)
     }
 }
 
 impl<B: IntoBuf> Future for Stream<B> {
     type Item = Response<Body<B>>;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         self.poll_response()
@@ -217,24 +224,27 @@ impl<B: IntoBuf> Body<B> {
         self.inner.body_is_empty()
     }
 
-    pub fn release_capacity(&mut self, sz: usize) -> Result<(), ConnectionError> {
+    pub fn release_capacity(&mut self, sz: usize) -> Result<(), ::Error> {
         self.inner.release_capacity(sz as proto::WindowSize)
+            .map_err(Into::into)
     }
 
     /// Poll trailers
     ///
     /// This function **must** not be called until `Body::poll` returns `None`.
-    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, ConnectionError> {
+    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, ::Error> {
         self.inner.poll_trailers()
+            .map_err(Into::into)
     }
 }
 
 impl<B: IntoBuf> ::futures::Stream for Body<B> {
     type Item = Bytes;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
         self.inner.poll_data()
+            .map_err(Into::into)
     }
 }
 
@@ -251,7 +261,7 @@ impl proto::Peer for Peer {
     fn convert_send_message(
         id: StreamId,
         request: Self::Send,
-        end_of_stream: bool) -> frame::Headers
+        end_of_stream: bool) -> Headers
     {
         use http::request::Parts;
 
@@ -259,10 +269,10 @@ impl proto::Peer for Peer {
 
         // Build the set pseudo header set. All requests will include `method`
         // and `path`.
-        let pseudo = frame::Pseudo::request(method, uri);
+        let pseudo = Pseudo::request(method, uri);
 
         // Create the HEADERS frame
-        let mut frame = frame::Headers::new(id, pseudo, headers);
+        let mut frame = Headers::new(id, pseudo, headers);
 
         if end_of_stream {
             frame.set_end_stream()
@@ -271,7 +281,7 @@ impl proto::Peer for Peer {
         frame
     }
 
-    fn convert_poll_message(headers: frame::Headers) -> Result<Self::Poll, ProtoError> {
+    fn convert_poll_message(headers: Headers) -> Result<Self::Poll, RecvError> {
         let mut b = Response::builder();
 
         let stream_id = headers.stream_id();
@@ -286,7 +296,7 @@ impl proto::Peer for Peer {
             Err(_) => {
                 // TODO: Should there be more specialized handling for different
                 // kinds of errors
-                return Err(ProtoError::Stream {
+                return Err(RecvError::Stream {
                     id: stream_id,
                     reason: ProtocolError,
                 });

src/codec/error.rs

@@ -0,0 +1,121 @@
+use frame::{Reason, StreamId};
+
+use std::{error, fmt, io};
+
+/// Errors that are received
+#[derive(Debug)]
+pub enum RecvError {
+    Connection(Reason),
+    Stream {
+        id: StreamId,
+        reason: Reason,
+    },
+    Io(io::Error),
+}
+
+/// Errors caused by sending a message
+#[derive(Debug)]
+pub enum SendError {
+    /// User error
+    User(UserError),
+
+    /// I/O error
+    Io(io::Error),
+}
+
+/// Errors caused by users of the library
+#[derive(Debug)]
+pub enum UserError {
+    /// The stream ID is no longer accepting frames.
+    InactiveStreamId,
+
+    /// The stream is not currently expecting a frame of this type.
+    UnexpectedFrameType,
+
+    /// The payload size is too big
+    PayloadTooBig,
+
+    /// The application attempted to initiate too many streams to remote.
+    Rejected,
+}
+
+// ===== impl RecvError =====
+
+impl From<io::Error> for RecvError {
+    fn from(src: io::Error) -> Self {
+        RecvError::Io(src)
+    }
+}
+
+impl error::Error for RecvError {
+    fn description(&self) -> &str {
+        use self::RecvError::*;
+
+        match *self {
+            Connection(ref reason) => reason.description(),
+            Stream { ref reason, .. } => reason.description(),
+            Io(ref e) => e.description(),
+        }
+    }
+}
+
+impl fmt::Display for RecvError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use std::error::Error;
+        write!(fmt, "{}", self.description())
+    }
+}
+
+// ===== impl SendError =====
+
+impl error::Error for SendError {
+    fn description(&self) -> &str {
+        use self::SendError::*;
+
+        match *self {
+            User(ref e) => e.description(),
+            Io(ref e) => e.description(),
+        }
+    }
+}
+
+impl fmt::Display for SendError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use std::error::Error;
+        write!(fmt, "{}", self.description())
+    }
+}
+
+impl From<io::Error> for SendError {
+    fn from(src: io::Error) -> Self {
+        SendError::Io(src)
+    }
+}
+
+impl From<UserError> for SendError {
+    fn from(src: UserError) -> Self {
+        SendError::User(src)
+    }
+}
+
+// ===== impl UserError =====
+
+impl error::Error for UserError {
+    fn description(&self) -> &str {
+        use self::UserError::*;
+
+        match *self {
+            InactiveStreamId => "inactive stream",
+            UnexpectedFrameType => "unexpected frame type",
+            PayloadTooBig => "payload too big",
+            Rejected => "rejected",
+        }
+    }
+}
+
+impl fmt::Display for UserError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use std::error::Error;
+        write!(fmt, "{}", self.description())
+    }
+}

src/codec/framed_read.rs

@@ -1,8 +1,9 @@
-use {hpack, ConnectionError};
+use codec::RecvError;
 use frame::{self, Frame, Kind};
 use frame::DEFAULT_SETTINGS_HEADER_TABLE_SIZE;
-use proto::*;
+use frame::Reason::*;
-use error::Reason::*;
+
+use hpack;
 
 use futures::*;
 
@@ -11,8 +12,6 @@ use bytes::BytesMut;
 use tokio_io::AsyncRead;
 use tokio_io::codec::length_delimited;
 
-use std::io;
-
 #[derive(Debug)]
 pub struct FramedRead<T> {
     inner: length_delimited::FramedRead<T>,
@@ -54,8 +53,8 @@ impl<T> FramedRead<T> {
         // TODO: Is this needed?
     }
 
-    fn decode_frame(&mut self, mut bytes: BytesMut) -> Result<Option<Frame>, ProtoError> {
+    fn decode_frame(&mut self, mut bytes: BytesMut) -> Result<Option<Frame>, RecvError> {
-        use self::ProtoError::*;
+        use self::RecvError::*;
 
         trace!("decoding frame from {}B", bytes.len());
 
@@ -226,11 +225,11 @@ impl<T> FramedRead<T> {
     }
 }
 
-impl<T> futures::Stream for FramedRead<T>
+impl<T> Stream for FramedRead<T>
     where T: AsyncRead,
 {
     type Item = Frame;
-    type Error = ProtoError;
+    type Error = RecvError;
 
     fn poll(&mut self) -> Poll<Option<Frame>, Self::Error> {
         loop {
@@ -247,32 +246,3 @@ impl<T> futures::Stream for FramedRead<T>
         }
     }
 }
-
-impl<T: Sink> Sink for FramedRead<T> {
-    type SinkItem = T::SinkItem;
-    type SinkError = T::SinkError;
-
-    fn start_send(&mut self, item: T::SinkItem) -> StartSend<T::SinkItem, T::SinkError> {
-        self.inner.get_mut().start_send(item)
-    }
-
-    fn poll_complete(&mut self) -> Poll<(), T::SinkError> {
-        self.inner.get_mut().poll_complete()
-    }
-}
-
-impl<T: AsyncWrite, B: Buf> FramedRead<FramedWrite<T, B>> {
-    pub fn poll_ready(&mut self) -> Poll<(), ConnectionError> {
-        self.inner.get_mut().poll_ready()
-    }
-}
-
-impl<T: io::Write> io::Write for FramedRead<T> {
-    fn write(&mut self, src: &[u8]) -> io::Result<usize> {
-        self.inner.get_mut().write(src)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        self.inner.get_mut().flush()
-    }
-}

src/codec/framed_write.rs

@@ -1,6 +1,7 @@
-use {hpack, ConnectionError};
+use codec::UserError;
-use error::User::*;
+use codec::UserError::*;
 use frame::{self, Frame, FrameSize};
+use hpack;
 
 use futures::*;
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -64,10 +65,14 @@ impl<T, B> FramedWrite<T, B>
         }
     }
 
-    pub fn poll_ready(&mut self) -> Poll<(), ConnectionError> {
+    /// Returns `Ready` when `send` is able to accept a frame
+    ///
+    /// Calling this function may result in the current contents of the buffer
+    /// to be flushed to `T`.
+    pub fn poll_ready(&mut self) -> Poll<(), io::Error> {
         if !self.has_capacity() {
             // Try flushing
-            try!(self.poll_complete());
+            try!(self.flush());
 
             if !self.has_capacity() {
                 return Ok(Async::NotReady);
@@ -77,47 +82,13 @@ impl<T, B> FramedWrite<T, B>
         Ok(Async::Ready(()))
     }
 
-    fn has_capacity(&self) -> bool {
+    /// Buffer a frame.
-        self.next.is_none() && self.buf.get_ref().remaining_mut() >= MIN_BUFFER_CAPACITY
+    ///
-    }
+    /// `poll_ready` must be called first to ensure that a frame may be
-
+    /// accepted.
-    fn is_empty(&self) -> bool {
+    pub fn buffer(&mut self, item: Frame<B>) -> Result<(), UserError> {
-        match self.next {
+        // Ensure that we have enough capacity to accept the write.
-            Some(Next::Data(ref frame)) => !frame.payload().has_remaining(),
+        assert!(self.has_capacity());
-            _ => !self.buf.has_remaining(),
-        }
-    }
-}
-
-impl<T, B> FramedWrite<T, B> {
-    pub fn max_frame_size(&self) -> usize {
-        self.max_frame_size as usize
-    }
-
-    pub fn apply_remote_settings(&mut self, settings: &frame::Settings) {
-        if let Some(val) = settings.max_frame_size() {
-            self.max_frame_size = val;
-        }
-    }
-
-    pub fn take_last_data_frame(&mut self) -> Option<frame::Data<B>> {
-        self.last_data_frame.take()
-    }
-}
-
-impl<T, B> Sink for FramedWrite<T, B>
-    where T: AsyncWrite,
-          B: Buf,
-{
-    type SinkItem = Frame<B>;
-    type SinkError = ConnectionError;
-
-    fn start_send(&mut self, item: Self::SinkItem)
-        -> StartSend<Self::SinkItem, ConnectionError>
-    {
-        if !try!(self.poll_ready()).is_ready() {
-            return Ok(AsyncSink::NotReady(item));
-        }
 
         debug!("send; frame={:?}", item);
 
@@ -127,7 +98,7 @@ impl<T, B> Sink for FramedWrite<T, B>
                 let len = v.payload().remaining();
 
                 if len > self.max_frame_size() {
-                    return Err(PayloadTooBig.into());
+                    return Err(PayloadTooBig);
                 }
 
                 if len >= CHAIN_THRESHOLD {
@@ -188,11 +159,12 @@ impl<T, B> Sink for FramedWrite<T, B>
             }
         }
 
-        Ok(AsyncSink::Ready)
+        Ok(())
     }
 
-    fn poll_complete(&mut self) -> Poll<(), ConnectionError> {
+    /// Flush buffered data to the wire
-        trace!("poll_complete");
+    pub fn flush(&mut self) -> Poll<(), io::Error> {
+        trace!("flush");
 
         while !self.is_empty() {
             match self.next {
@@ -228,18 +200,44 @@ impl<T, B> Sink for FramedWrite<T, B>
         Ok(Async::Ready(()))
     }
 
-    fn close(&mut self) -> Poll<(), ConnectionError> {
+    /// Close the codec
-        try_ready!(self.poll_complete());
+    pub fn shutdown(&mut self) -> Poll<(), io::Error> {
+        try_ready!(self.flush());
         self.inner.shutdown().map_err(Into::into)
     }
+
+    fn has_capacity(&self) -> bool {
+        self.next.is_none() && self.buf.get_ref().remaining_mut() >= MIN_BUFFER_CAPACITY
+    }
+
+    fn is_empty(&self) -> bool {
+        match self.next {
+            Some(Next::Data(ref frame)) => !frame.payload().has_remaining(),
+            _ => !self.buf.has_remaining(),
+        }
+    }
 }
 
-impl<T: Stream, B> Stream for FramedWrite<T, B> {
+impl<T, B> FramedWrite<T, B> {
-    type Item = T::Item;
+    /// Returns the max frame size that can be sent
-    type Error = T::Error;
+    pub fn max_frame_size(&self) -> usize {
+        self.max_frame_size as usize
+    }
 
-    fn poll(&mut self) -> Poll<Option<T::Item>, T::Error> {
+    /// Apply settings received by the peer
-        self.inner.poll()
+    pub fn apply_remote_settings(&mut self, settings: &frame::Settings) {
+        if let Some(val) = settings.max_frame_size() {
+            self.max_frame_size = val;
+        }
+    }
+
+    /// Retrieve the last data frame that has been sent
+    pub fn take_last_data_frame(&mut self) -> Option<frame::Data<B>> {
+        self.last_data_frame.take()
+    }
+
+    pub fn get_mut(&mut self) -> &mut T {
+        &mut self.inner
     }
 }
 

src/codec/mod.rs

@@ -0,0 +1,148 @@
+mod error;
+mod framed_read;
+mod framed_write;
+
+pub use self::error::{SendError, RecvError, UserError};
+
+use self::framed_read::FramedRead;
+use self::framed_write::FramedWrite;
+
+use frame::{self, Frame, Data, Settings};
+
+use futures::*;
+
+use tokio_io::{AsyncRead, AsyncWrite};
+use tokio_io::codec::length_delimited;
+
+use bytes::Buf;
+
+use std::io;
+
+#[derive(Debug)]
+pub struct Codec<T, B> {
+    inner: FramedRead<FramedWrite<T, B>>,
+}
+
+impl<T, B> Codec<T, B>
+    where T: AsyncRead + AsyncWrite,
+          B: Buf,
+{
+    pub fn new(io: T) -> Self {
+        // Wrap with writer
+        let framed_write = FramedWrite::new(io);
+
+        // Delimit the frames
+        let delimited = length_delimited::Builder::new()
+            .big_endian()
+            .length_field_length(3)
+            .length_adjustment(9)
+            .num_skip(0) // Don't skip the header
+            // TODO: make this configurable and allow it to be changed during
+            // runtime.
+            .max_frame_length(frame::DEFAULT_MAX_FRAME_SIZE as usize)
+            .new_read(framed_write);
+
+        let inner = FramedRead::new(delimited);
+
+        Codec { inner }
+    }
+}
+
+impl<T, B> Codec<T, B> {
+    /// Apply a settings received from the peer
+    pub fn apply_remote_settings(&mut self, frame: &Settings) {
+        self.framed_read().apply_remote_settings(frame);
+        self.framed_write().apply_remote_settings(frame);
+    }
+
+    /// Takes the data payload value that was fully written to the socket
+    pub fn take_last_data_frame(&mut self) -> Option<Data<B>> {
+        self.framed_write().take_last_data_frame()
+    }
+
+    /// Returns the max frame size that can be sent to the peer
+    pub fn max_send_frame_size(&self) -> usize {
+        self.inner.get_ref().max_frame_size()
+    }
+
+    pub fn get_mut(&mut self) -> &mut T {
+        self.inner.get_mut().get_mut()
+    }
+
+    fn framed_read(&mut self) -> &mut FramedRead<FramedWrite<T, B>> {
+        &mut self.inner
+    }
+
+    fn framed_write(&mut self) -> &mut FramedWrite<T, B> {
+        self.inner.get_mut()
+    }
+}
+
+impl<T, B> Codec<T, B>
+    where T: AsyncWrite,
+          B: Buf,
+{
+    /// Returns `Ready` when the codec can buffer a frame
+    pub fn poll_ready(&mut self) -> Poll<(), io::Error> {
+        self.framed_write().poll_ready()
+    }
+
+    /// Buffer a frame.
+    ///
+    /// `poll_ready` must be called first to ensure that a frame may be
+    /// accepted.
+    ///
+    /// TODO: Rename this to avoid conflicts with Sink::buffer
+    pub fn buffer(&mut self, item: Frame<B>) -> Result<(), UserError>
+    {
+        self.framed_write().buffer(item)
+    }
+
+    /// Flush buffered data to the wire
+    pub fn flush(&mut self) -> Poll<(), io::Error> {
+        self.framed_write().flush()
+    }
+
+    /// Shutdown the send half
+    pub fn shutdown(&mut self) -> Poll<(), io::Error> {
+        self.framed_write().shutdown()
+    }
+}
+
+impl<T, B> Stream for Codec<T, B>
+    where T: AsyncRead,
+{
+    type Item = Frame;
+    type Error = RecvError;
+
+    fn poll(&mut self) -> Poll<Option<Frame>, Self::Error> {
+        self.inner.poll()
+    }
+}
+
+impl<T, B> Sink for Codec<T, B>
+    where T: AsyncWrite,
+          B: Buf,
+{
+    type SinkItem = Frame<B>;
+    type SinkError = SendError;
+
+    fn start_send(&mut self, item: Self::SinkItem) -> StartSend<Self::SinkItem, Self::SinkError> {
+        if !self.poll_ready()?.is_ready() {
+            return Ok(AsyncSink::NotReady(item));
+        }
+
+        self.buffer(item)?;
+        Ok(AsyncSink::Ready)
+    }
+
+    fn poll_complete(&mut self) -> Poll<(), Self::SinkError> {
+        self.flush()?;
+        Ok(Async::Ready(()))
+    }
+
+    fn close(&mut self) -> Poll<(), Self::SinkError> {
+        self.shutdown()?;
+        Ok(Async::Ready(()))
+    }
+}

src/error.rs

@@ -1,263 +1,101 @@
-use http;
+use codec::{SendError, UserError};
+use proto;
+
 use std::{error, fmt, io};
 
+pub use frame::Reason;
+
 /// The error type for HTTP/2 operations
-///
-/// XXX does this sufficiently destinguish stream-level errors from connection-level errors?
 #[derive(Debug)]
-pub enum ConnectionError {
+pub struct Error {
+    kind: Kind,
+}
+
+#[derive(Debug)]
+enum Kind {
     /// An error caused by an action taken by the remote peer.
     ///
     /// This is either an error received by the peer or caused by an invalid
     /// action taken by the peer (i.e. a protocol error).
     Proto(Reason),
 
-    /// An `io::Error` occurred while trying to read or write.
-    Io(io::Error),
-
     /// An error resulting from an invalid action taken by the user of this
     /// library.
-    User(User),
+    User(UserError),
 
-    // TODO: reserve additional variants
+    /// An `io::Error` occurred while trying to read or write.
+    Io(io::Error),
 }
 
-#[derive(Debug)]
+// ===== impl Error =====
-pub struct StreamError(Reason);
 
-impl StreamError {
+impl From<proto::Error> for Error {
-   pub fn new(r: Reason) -> StreamError {
+    fn from(src: proto::Error) -> Error {
-       StreamError(r)
+        use proto::Error::*;
+
+        Error {
+            kind: match src {
+                Proto(reason) => Kind::Proto(reason),
+                Io(e) => Kind::Io(e),
+            },
         }
-
-   pub fn reason(&self) -> Reason {
-       self.0
     }
 }
 
-impl From<Reason> for StreamError {
+impl From<io::Error> for Error {
-    fn from(r: Reason) -> Self {
+    fn from(src: io::Error) -> Error {
-        StreamError(r)
+        Error { kind: Kind::Io(src) }
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+impl From<Reason> for Error {
-pub enum Reason {
+    fn from(src: Reason) -> Error {
-    NoError,
+        Error { kind: Kind::Proto(src) }
-    ProtocolError,
-    InternalError,
-    FlowControlError,
-    SettingsTimeout,
-    StreamClosed,
-    FrameSizeError,
-    RefusedStream,
-    Cancel,
-    CompressionError,
-    ConnectError,
-    EnhanceYourCalm,
-    InadequateSecurity,
-    Http11Required,
-    Other(u32),
-    // TODO: reserve additional variants
-}
-
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub enum User {
-    /// The specified stream ID is invalid.
-    ///
-    /// For example, using a stream ID reserved for a push promise from the
-    /// client or using a non-zero stream ID for settings.
-    InvalidStreamId,
-
-    /// The stream ID is no longer accepting frames.
-    InactiveStreamId,
-
-    /// The stream is not currently expecting a frame of this type.
-    UnexpectedFrameType,
-
-    /// The connection or stream does not have a sufficient flow control window to
-    /// transmit a Data frame to the remote.
-    FlowControlViolation,
-
-    /// The payload size is too big
-    PayloadTooBig,
-
-    /// The connection state is corrupt and the connection should be dropped.
-    Corrupt,
-
-    /// The stream state has been reset.
-    StreamReset(Reason),
-
-    /// The application attempted to initiate too many streams to remote.
-    Rejected,
-
-    // TODO: reserve additional variants
-}
-
-macro_rules! reason_desc {
-    ($reason:expr) => (reason_desc!($reason, ""));
-    ($reason:expr, $prefix:expr) => ({
-        use self::Reason::*;
-
-        match $reason {
-            NoError => concat!($prefix, "not a result of an error"),
-            ProtocolError => concat!($prefix, "unspecific protocol error detected"),
-            InternalError => concat!($prefix, "unexpected internal error encountered"),
-            FlowControlError => concat!($prefix, "flow-control protocol violated"),
-            SettingsTimeout => concat!($prefix, "settings ACK not received in timely manner"),
-            StreamClosed => concat!($prefix, "received frame when stream half-closed"),
-            FrameSizeError => concat!($prefix, "frame sent with invalid size"),
-            RefusedStream => concat!($prefix, "refused stream before processing any application logic"),
-            Cancel => concat!($prefix, "stream no longer needed"),
-            CompressionError => concat!($prefix, "unable to maintain the header compression context"),
-            ConnectError => concat!($prefix, "connection established in response to a CONNECT request was reset or abnormally closed"),
-            EnhanceYourCalm => concat!($prefix, "detected excessive load generating behavior"),
-            InadequateSecurity => concat!($prefix, "security properties do not meet minimum requirements"),
-            Http11Required => concat!($prefix, "endpoint requires HTTP/1.1"),
-            Other(_) => concat!($prefix, "other reason (ain't no tellin')"),
-        }
-    });
-}
-
-macro_rules! user_desc {
-    ($reason:expr) => (user_desc!($reason, ""));
-    ($reason:expr, $prefix:expr) => ({
-        use self::User::*;
-
-        match $reason {
-            InvalidStreamId => concat!($prefix, "invalid stream ID"),
-            InactiveStreamId => concat!($prefix, "inactive stream ID"),
-            UnexpectedFrameType => concat!($prefix, "unexpected frame type"),
-            FlowControlViolation => concat!($prefix, "flow control violation"),
-            StreamReset(_) => concat!($prefix, "frame sent on reset stream"),
-            Corrupt => concat!($prefix, "connection state corrupt"),
-            Rejected => concat!($prefix, "stream would exceed remote max concurrency"),
-            PayloadTooBig => concat!($prefix, "payload too big"),
-        }
-    });
-}
-
-// ===== impl ConnectionError =====
-
-impl From<io::Error> for ConnectionError {
-    fn from(src: io::Error) -> ConnectionError {
-        ConnectionError::Io(src)
     }
 }
 
-impl From<Reason> for ConnectionError {
+impl From<SendError> for Error {
-    fn from(src: Reason) -> ConnectionError {
+    fn from(src: SendError) -> Error {
-        ConnectionError::Proto(src)
+        match src {
+            SendError::User(e) => e.into(),
+            SendError::Io(e) => e.into(),
+        }
     }
 }
 
-impl From<User> for ConnectionError {
+impl From<UserError> for Error {
-    fn from(src: User) -> ConnectionError {
+    fn from(src: UserError) -> Error {
-        ConnectionError::User(src)
+        Error { kind: Kind::User(src) }
     }
 }
 
-impl From<ConnectionError> for io::Error {
+impl fmt::Display for Error {
-    fn from(src: ConnectionError) -> io::Error {
-        io::Error::new(io::ErrorKind::Other, src)
-    }
-}
-
-impl From<http::Error> for ConnectionError {
-    fn from(_: http::Error) -> Self {
-        // TODO: Should this always be a protocol error?
-        Reason::ProtocolError.into()
-    }
-}
-
-impl fmt::Display for ConnectionError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        use self::ConnectionError::*;
+        use self::Kind::*;
 
-        match *self {
+        match self.kind {
-            Proto(reason) => write!(fmt, "protocol error: {}", reason),
+            Proto(ref reason) => write!(fmt, "protocol error: {}", reason),
+            User(ref e) => write!(fmt, "user error: {}", e),
             Io(ref e) => fmt::Display::fmt(e, fmt),
-            User(e) => write!(fmt, "user error: {}", e),
         }
     }
 }
 
-impl error::Error for ConnectionError {
+impl error::Error for Error {
     fn description(&self) -> &str {
-        use self::ConnectionError::*;
+        use self::Kind::*;
 
-        match *self {
+        match self.kind {
             Io(ref e) => error::Error::description(e),
-            Proto(reason) => reason_desc!(reason, "protocol error: "),
+            Proto(ref reason) => reason.description(),
-            User(user) => user_desc!(user, "user error: "),
+            User(ref user) => user.description(),
         }
     }
 }
 
-// ===== impl Reason =====
-
-impl Reason {
-    pub fn description(&self) -> &str {
-        reason_desc!(*self)
-    }
-}
-
-impl From<u32> for Reason {
-    fn from(src: u32) -> Reason {
-        use self::Reason::*;
-
-        match src {
-            0x0 => NoError,
-            0x1 => ProtocolError,
-            0x2 => InternalError,
-            0x3 => FlowControlError,
-            0x4 => SettingsTimeout,
-            0x5 => StreamClosed,
-            0x6 => FrameSizeError,
-            0x7 => RefusedStream,
-            0x8 => Cancel,
-            0x9 => CompressionError,
-            0xa => ConnectError,
-            0xb => EnhanceYourCalm,
-            0xc => InadequateSecurity,
-            0xd => Http11Required,
-            _ => Other(src),
-        }
-    }
-}
-
-impl From<Reason> for u32 {
-    fn from(src: Reason) -> u32 {
-        use self::Reason::*;
-
-        match src {
-            NoError => 0x0,
-            ProtocolError => 0x1,
-            InternalError => 0x2,
-            FlowControlError => 0x3,
-            SettingsTimeout => 0x4,
-            StreamClosed => 0x5,
-            FrameSizeError => 0x6,
-            RefusedStream => 0x7,
-            Cancel => 0x8,
-            CompressionError => 0x9,
-            ConnectError => 0xa,
-            EnhanceYourCalm => 0xb,
-            InadequateSecurity => 0xc,
-            Http11Required => 0xd,
-            Other(v) => v,
-        }
-    }
-}
-
-impl fmt::Display for Reason {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        write!(fmt, "{}", self.description())
-    }
-}
-
 // ===== impl User =====
 
+/*
 impl User {
     pub fn description(&self) -> &str {
         user_desc!(*self)
@@ -269,3 +107,4 @@ impl fmt::Display for User {
         write!(fmt, "{}", self.description())
     }
 }
+*/

src/frame/go_away.rs

@@ -1,5 +1,4 @@
-use error::Reason;
+use frame::{self, Head, Error, Kind, StreamId, Reason};
-use frame::{self, Head, Error, Kind, StreamId};
 
 use bytes::{BufMut, BigEndian};
 

src/frame/headers.rs

@@ -1,9 +1,8 @@
 use super::{StreamId, StreamDependency};
 use hpack;
 use frame::{self, Frame, Head, Kind, Error};
-use HeaderMap;
 
-use http::{uri, Method, StatusCode, Uri};
+use http::{uri, Method, StatusCode, Uri, HeaderMap};
 use http::header::{self, HeaderName, HeaderValue};
 
 use bytes::{BytesMut, Bytes};

src/frame/mod.rs

@@ -1,5 +1,4 @@
 use hpack;
-use error::{ConnectionError, Reason};
 
 use bytes::Bytes;
 
@@ -33,6 +32,7 @@ mod head;
 mod headers;
 mod ping;
 mod priority;
+mod reason;
 mod reset;
 mod settings;
 mod stream_id;
@@ -45,6 +45,7 @@ pub use self::head::{Head, Kind};
 pub use self::headers::{Headers, PushPromise, Continuation, Pseudo};
 pub use self::ping::Ping;
 pub use self::priority::{Priority, StreamDependency};
+pub use self::reason::Reason;
 pub use self::reset::Reset;
 pub use self::settings::Settings;
 pub use self::stream_id::StreamId;
@@ -113,15 +114,6 @@ impl<T> fmt::Debug for Frame<T> {
 /// Errors that can occur during parsing an HTTP/2 frame.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Error {
-    /// A full frame header was not passed.
-    Short,
-
-    /// An unsupported value was set for the flag value.
-    BadFlag,
-
-    /// An unsupported value was set for the frame kind.
-    BadKind,
-
     /// A length value other than 8 was set on a PING message.
     BadFrameSize,
 
@@ -129,19 +121,6 @@ pub enum Error {
     /// length of the payload.
     TooMuchPadding,
 
-    /// The payload length specified by the frame header was shorter than
-    /// necessary for the parser settings specified and the frame type.
-    ///
-    /// This happens if, for instance, the priority flag is set and the
-    /// header length is shorter than a stream dependency.
-    ///
-    /// `PayloadLengthTooShort` should be treated as a protocol error.
-    PayloadLengthTooShort,
-
-    /// The payload length specified by the frame header of a settings frame
-    /// was not a round multiple of the size of a single setting.
-    PartialSettingLength,
-
     /// An invalid setting value was provided
     InvalidSettingValue,
 
@@ -173,14 +152,3 @@ pub enum Error {
     /// Failed to perform HPACK decoding
     Hpack(hpack::DecoderError),
 }
-
-// ===== impl Error =====
-
-impl From<Error> for ConnectionError {
-    fn from(src: Error) -> ConnectionError {
-        match src {
-            // TODO: implement
-            _ => ConnectionError::Proto(Reason::ProtocolError),
-        }
-    }
-}

src/frame/reader.rs

@@ -1,40 +0,0 @@
-use ConnectionError;
-use super::Frame;
-use futures::*;
-use bytes::BytesMut;
-use std::io;
-
-pub struct Reader<T> {
-    inner: T,
-}
-
-impl<T> Stream for Reader<T>
-    where T: Stream<Item = BytesMut, Error = io::Error>,
-{
-    type Item = Frame;
-    type Error = ConnectionError;
-
-    fn poll(&mut self) -> Poll<Option<Frame>, ConnectionError> {
-        match try_ready!(self.inner.poll()) {
-            Some(bytes) => {
-                Frame::load(bytes.freeze())
-                    .map(|frame| Async::Ready(Some(frame)))
-                    .map_err(ConnectionError::from)
-            }
-            None => Ok(Async::Ready(None)),
-        }
-    }
-}
-
-impl<T: Sink> Sink for Reader<T> {
-    type SinkItem = T::SinkItem;
-    type SinkError = T::SinkError;
-
-    fn start_send(&mut self, item: T::SinkItem) -> StartSend<T::SinkItem, T::SinkError> {
-        self.inner.start_send(item)
-    }
-
-    fn poll_complete(&mut self) -> Poll<(), T::SinkError> {
-        self.inner.poll_complete()
-    }
-}

src/frame/reason.rs

@@ -0,0 +1,101 @@
+use std::fmt;
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Reason {
+    NoError,
+    ProtocolError,
+    InternalError,
+    FlowControlError,
+    SettingsTimeout,
+    StreamClosed,
+    FrameSizeError,
+    RefusedStream,
+    Cancel,
+    CompressionError,
+    ConnectError,
+    EnhanceYourCalm,
+    InadequateSecurity,
+    Http11Required,
+    Other(u32),
+    // TODO: reserve additional variants
+}
+
+// ===== impl Reason =====
+
+impl Reason {
+    pub fn description(&self) -> &str {
+        use self::Reason::*;
+
+        match *self {
+            NoError => "not a result of an error",
+            ProtocolError => "unspecific protocol error detected",
+            InternalError => "unexpected internal error encountered",
+            FlowControlError => "flow-control protocol violated",
+            SettingsTimeout => "settings ACK not received in timely manner",
+            StreamClosed => "received frame when stream half-closed",
+            FrameSizeError => "frame sent with invalid size",
+            RefusedStream => "refused stream before processing any application logic",
+            Cancel => "stream no longer needed",
+            CompressionError => "unable to maintain the header compression context",
+            ConnectError => "connection established in response to a CONNECT request was reset or abnormally closed",
+            EnhanceYourCalm => "detected excessive load generating behavior",
+            InadequateSecurity => "security properties do not meet minimum requirements",
+            Http11Required => "endpoint requires HTTP/1.1",
+            Other(_) => "other reason (ain't no tellin')",
+        }
+    }
+}
+
+impl From<u32> for Reason {
+    fn from(src: u32) -> Reason {
+        use self::Reason::*;
+
+        match src {
+            0x0 => NoError,
+            0x1 => ProtocolError,
+            0x2 => InternalError,
+            0x3 => FlowControlError,
+            0x4 => SettingsTimeout,
+            0x5 => StreamClosed,
+            0x6 => FrameSizeError,
+            0x7 => RefusedStream,
+            0x8 => Cancel,
+            0x9 => CompressionError,
+            0xa => ConnectError,
+            0xb => EnhanceYourCalm,
+            0xc => InadequateSecurity,
+            0xd => Http11Required,
+            _ => Other(src),
+        }
+    }
+}
+
+impl From<Reason> for u32 {
+    fn from(src: Reason) -> u32 {
+        use self::Reason::*;
+
+        match src {
+            NoError => 0x0,
+            ProtocolError => 0x1,
+            InternalError => 0x2,
+            FlowControlError => 0x3,
+            SettingsTimeout => 0x4,
+            StreamClosed => 0x5,
+            FrameSizeError => 0x6,
+            RefusedStream => 0x7,
+            Cancel => 0x8,
+            CompressionError => 0x9,
+            ConnectError => 0xa,
+            EnhanceYourCalm => 0xb,
+            InadequateSecurity => 0xc,
+            Http11Required => 0xd,
+            Other(v) => v,
+        }
+    }
+}
+
+impl fmt::Display for Reason {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{}", self.description())
+    }
+}

src/frame/reset.rs

@@ -1,5 +1,4 @@
-use error::Reason;
+use frame::{self, Head, Error, Kind, StreamId, Reason};
-use frame::{self, Head, Error, Kind, StreamId};
 
 use bytes::{BufMut, BigEndian};
 

src/frame/unknown.rs

@@ -1,33 +0,0 @@
-use frame::{Frame, Head, Error};
-use bytes::{Bytes, BytesMut, BufMut};
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Unknown {
-    head: Head,
-    payload: Bytes,
-}
-
-impl Unknown {
-    pub fn new(head: Head, payload: Bytes) -> Unknown {
-        Unknown {
-            head: head,
-            payload: payload,
-        }
-    }
-
-    pub fn encode_len(&self) -> usize {
-        self.head.encode_len() + self.payload.len()
-    }
-
-    pub fn encode(&self, dst: &mut BytesMut) -> Result<(), Error> {
-        try!(self.head.encode(self.payload.len(), dst));
-        dst.put(&self.payload);
-        Ok(())
-    }
-}
-
-impl From<Unknown> for Frame {
-    fn from(src: Unknown) -> Frame {
-        Frame::Unknown(src)
-    }
-}

src/frame/writer.rs

@@ -1 +0,0 @@
-pub struct Writer;

src/lib.rs

@@ -24,14 +24,13 @@ extern crate log;
 
 extern crate string;
 
-pub mod client;
+mod error;
-pub mod error;
+mod codec;
 mod hpack;
 mod proto;
 mod frame;
+
+pub mod client;
 pub mod server;
 
-pub use error::{ConnectionError, Reason};
+pub use error::{Error, Reason};
-
-// TODO: remove if carllerche/http#90 lands
-pub type HeaderMap = http::HeaderMap<http::header::HeaderValue>;

src/proto/codec.rs

@@ -1,77 +0,0 @@
-use super::*;
-use futures::*;
-
-#[derive(Debug)]
-pub struct Codec<T, B> {
-    inner: FramedRead<FramedWrite<T, B>>,
-}
-
-impl<T, B> Codec<T, B> {
-    pub fn apply_remote_settings(&mut self, frame: &frame::Settings) {
-        self.framed_read().apply_remote_settings(frame);
-        self.framed_write().apply_remote_settings(frame);
-    }
-
-    /// Takes the data payload value that was fully written to the socket
-    pub(crate) fn take_last_data_frame(&mut self) -> Option<frame::Data<B>> {
-        self.framed_write().take_last_data_frame()
-    }
-
-    pub fn max_send_frame_size(&self) -> usize {
-        self.inner.get_ref().max_frame_size()
-    }
-
-    fn framed_read(&mut self) -> &mut FramedRead<FramedWrite<T, B>> {
-        &mut self.inner
-    }
-
-    fn framed_write(&mut self) -> &mut FramedWrite<T, B> {
-        self.inner.get_mut()
-    }
-}
-
-impl<T, B> Codec<T, B>
-    where T: AsyncRead + AsyncWrite,
-          B: Buf,
-{
-    pub fn from_framed(inner: FramedRead<FramedWrite<T, B>>) -> Self {
-        Codec { inner }
-    }
-}
-
-impl<T, B> Codec<T, B>
-    where T: AsyncWrite,
-          B: Buf,
-{
-    pub fn poll_ready(&mut self) -> Poll<(), ConnectionError> {
-        self.inner.poll_ready()
-    }
-
-}
-
-impl<T, B> futures::Stream for Codec<T, B>
-    where T: AsyncRead,
-{
-    type Item = Frame;
-    type Error = ProtoError;
-
-    fn poll(&mut self) -> Poll<Option<Frame>, Self::Error> {
-        self.inner.poll()
-    }
-}
-
-impl<T, B> Sink for Codec<T, B>
-    where T: AsyncWrite,
-          B: Buf,
-{
-    type SinkItem = Frame<B>;
-    type SinkError = ConnectionError;
-
-    fn start_send(&mut self, item: Self::SinkItem) -> StartSend<Self::SinkItem, Self::SinkError> {
-        self.inner.start_send(item)
-    }
-
-    fn poll_complete(&mut self) -> Poll<(), Self::SinkError> {
-        self.inner.poll_complete()
-    }
-}

src/proto/connection.rs

@@ -1,9 +1,11 @@
-use {client, frame, server, ConnectionError};
+use {client, frame, server, proto};
+use frame::Reason;
+use codec::{SendError, RecvError};
 
 use proto::*;
 
 use http::Request;
-use futures::{Sink, Stream};
+use futures::{Stream};
 use bytes::{Bytes, IntoBuf};
 use tokio_io::{AsyncRead, AsyncWrite};
 
@@ -73,7 +75,10 @@ impl<T, P, B> Connection<T, P, B>
     }
 
     /// Returns `Ready` when the connection is ready to receive a frame.
-    fn poll_ready(&mut self) -> Poll<(), ConnectionError> {
+    ///
+    /// Returns `RecvError` as this may raise errors that are caused by delayed
+    /// processing of received frames.
+    fn poll_ready(&mut self) -> Poll<(), RecvError> {
         // The order of these calls don't really matter too much as only one
         // should have pending work.
         try_ready!(self.ping_pong.send_pending_pong(&mut self.codec));
@@ -83,84 +88,97 @@ impl<T, P, B> Connection<T, P, B>
         Ok(().into())
     }
 
-    /// Returns `Ready` when new the connection is able to support a new request stream.
-    pub fn poll_send_request_ready(&mut self) -> Poll<(), ConnectionError> {
-        self.streams.poll_send_request_ready()
-    }
-
     /// Advances the internal state of the connection.
-    pub fn poll(&mut self) -> Poll<(), ConnectionError> {
+    pub fn poll(&mut self) -> Poll<(), proto::Error> {
-        use error::ConnectionError::*;
+        use codec::RecvError::*;
 
         loop {
+            // TODO: probably clean up this glob of code
             match self.state {
                 // When open, continue to poll a frame
-                State::Open => {},
+                State::Open => {
-                // In an error state
-                _ => {
-                    try_ready!(self.poll_complete());
-
-                    // GO_AWAY frame has been sent, return the error
-                    return Err(self.state.error().unwrap().into());
-                }
-            }
-
                     match self.poll2() {
-                Err(Proto(e)) => {
+                        // The connection has shutdown normally
+                        Ok(Async::Ready(())) => return Ok(().into()),
+                        // The connection is not ready to make progress
+                        Ok(Async::NotReady) => {
+                            // Ensure all window updates have been sent.
+                            //
+                            // This will also handle flushing `self.codec`
+                            try_ready!(self.streams.poll_complete(&mut self.codec));
+
+                            return Ok(Async::NotReady);
+                        }
+                        // Attempting to read a frame resulted in a connection level
+                        // error. This is handled by setting a GO_AWAY frame followed by
+                        // terminating the connection.
+                        Err(Connection(e)) => {
                             debug!("Connection::poll; err={:?}", e);
+
+                            // Reset all active streams
                             let last_processed_id = self.streams.recv_err(&e.into());
+
+                            // Create the GO_AWAY frame with the last_processed_id
                             let frame = frame::GoAway::new(last_processed_id, e);
 
+                            // Transition to the going away state.
                             self.state = State::GoAway(frame);
                         }
-                Err(e) => {
+                        // Attempting to read a frame resulted in a stream level error.
+                        // This is handled by resetting the frame then trying to read
+                        // another frame.
+                        Err(Stream { id, reason }) => {
+                            trace!("stream level error; id={:?}; reason={:?}", id, reason);
+                            self.streams.send_reset(id, reason);
+                        }
+                        // Attempting to read a frame resulted in an I/O error. All
+                        // active streams must be reset.
+                        //
                         // TODO: Are I/O errors recoverable?
+                        Err(Io(e)) => {
+                            let e = e.into();
+
+                            // Reset all active streams
                             self.streams.recv_err(&e);
+
+                            // Return the error
                             return Err(e);
                         }
-                ret => return ret,
+                    }
+                },
+                State::GoAway(frame) => {
+                    // Ensure the codec is ready to accept the frame
+                    try_ready!(self.codec.poll_ready());
+
+                    // Buffer the GO_AWAY frame
+                    self.codec.buffer(frame.into())
+                        .ok().expect("invalid GO_AWAY frame");
+
+                    // GO_AWAY sent, transition the connection to an errored state
+                    self.state = State::Flush(frame.reason());
+                }
+                State::Flush(reason) => {
+                    // Flush the codec
+                    try_ready!(self.codec.flush());
+
+                    // Transition the state to error
+                    self.state = State::Error(reason);
+                }
+                State::Error(reason) => {
+                    return Err(reason.into());
+                }
             }
         }
     }
 
-    fn poll2(&mut self) -> Poll<(), ConnectionError> {
+    fn poll2(&mut self) -> Poll<(), RecvError> {
         use frame::Frame::*;
-        use proto::ProtoError::*;
 
         loop {
             // First, ensure that the `Connection` is able to receive a frame
             try_ready!(self.poll_ready());
 
-            trace!("polling codec");
+            match try_ready!(self.codec.poll()) {
-
-            let frame = match self.codec.poll() {
-                // Receive a frame
-                Ok(Async::Ready(frame)) => frame,
-                // Socket not ready, try to flush any pending data
-                Ok(Async::NotReady) => {
-                    // Flush any pending writes
-                    let _ = try!(self.poll_complete());
-                    return Ok(Async::NotReady);
-                }
-                // Connection level error, set GO_AWAY and close connection
-                Err(Connection(reason)) => {
-                    return Err(ConnectionError::Proto(reason));
-                }
-                // Stream level error, reset the stream
-                Err(Stream { id, reason }) => {
-                    trace!("stream level error; id={:?}; reason={:?}", id, reason);
-                    self.streams.send_reset(id, reason);
-                    continue;
-                }
-                // I/O error, nothing more can be done
-                Err(Io(err)) => {
-                    return Err(err.into());
-                }
-            };
-
-            debug!("recv; frame={:?}", frame);
-
-            match frame {
                 Some(Headers(frame)) => {
                     trace!("recv HEADERS; frame={:?}", frame);
                     try!(self.streams.recv_headers(frame));
@@ -184,7 +202,7 @@ impl<T, P, B> Connection<T, P, B>
                 Some(GoAway(_)) => {
                     // TODO: handle the last_processed_id. Also, should this be
                     // handled as an error?
-                    // let _ = ConnectionError::Proto(frame.reason());
+                    // let _ = RecvError::Proto(frame.reason());
                     return Ok(().into());
                 }
                 Some(Ping(frame)) => {
@@ -207,46 +225,20 @@ impl<T, P, B> Connection<T, P, B>
             }
         }
     }
-
-    fn poll_complete(&mut self) -> Poll<(), ConnectionError> {
-        loop {
-            match self.state {
-                State::Open => {
-                    try_ready!(self.poll_ready());
-
-                    // Ensure all window updates have been sent.
-                    try_ready!(self.streams.poll_complete(&mut self.codec));
-
-                    return Ok(().into());
-                }
-                State::GoAway(frame) => {
-                    if !self.codec.start_send(frame.into())?.is_ready() {
-                        // Not ready to send the frame... try again later.
-                        return Ok(Async::NotReady);
-                    }
-
-                    // GO_AWAY sent, transition the connection to an errored state
-                    self.state = State::Flush(frame.reason());
-                }
-                State::Flush(reason) => {
-                    try_ready!(self.codec.poll_complete());
-                    self.state = State::Error(reason);
-                }
-                State::Error(..) => {
-                    return Ok(().into());
-                }
-            }
-        }
-    }
 }
 
 impl<T, B> Connection<T, client::Peer, B>
     where T: AsyncRead + AsyncWrite,
           B: IntoBuf,
 {
+    /// Returns `Ready` when new the connection is able to support a new request stream.
+    pub fn poll_send_request_ready(&mut self) -> Async<()> {
+        self.streams.poll_send_request_ready()
+    }
+
     /// Initialize a new HTTP/2.0 stream and send the message.
     pub fn send_request(&mut self, request: Request<()>, end_of_stream: bool)
-        -> Result<StreamRef<B::Buf, client::Peer>, ConnectionError>
+        -> Result<StreamRef<B::Buf, client::Peer>, SendError>
     {
         self.streams.send_request(request, end_of_stream)
     }
@@ -260,14 +252,3 @@ impl<T, B> Connection<T, server::Peer, B>
         self.streams.next_incoming()
     }
 }
-
-// ====== impl State =====
-
-impl State {
-    fn error(&self) -> Option<Reason> {
-        match *self {
-            State::Error(reason) => Some(reason),
-            _ => None,
-        }
-    }
-}

src/proto/error.rs

@@ -0,0 +1,34 @@
+use frame::Reason;
+use codec::RecvError;
+
+use std::io;
+
+/// Either an H2 reason  or an I/O error
+#[derive(Debug)]
+pub enum Error {
+    Proto(Reason),
+    Io(io::Error),
+}
+
+impl Error {
+    pub fn into_connection_recv_error(self) -> RecvError {
+        use self::Error::*;
+
+        match self {
+            Proto(reason) => RecvError::Connection(reason),
+            Io(e) => RecvError::Io(e),
+        }
+    }
+}
+
+impl From<Reason> for Error {
+    fn from(src: Reason) -> Self {
+        Error::Proto(src)
+    }
+}
+
+impl From<io::Error> for Error {
+    fn from(src: io::Error) -> Self {
+        Error::Io(src)
+    }
+}

src/proto/mod.rs

@@ -1,109 +1,35 @@
-mod codec;
 mod connection;
-mod framed_read;
+mod error;
-mod framed_write;
+mod peer;
 mod ping_pong;
 mod settings;
 mod streams;
 
 pub(crate) use self::connection::Connection;
+pub(crate) use self::error::Error;
+pub(crate) use self::peer::Peer;
 pub(crate) use self::streams::{Streams, StreamRef};
 
-use self::codec::Codec;
+use codec::Codec;
-use self::framed_read::FramedRead;
+
-use self::framed_write::FramedWrite;
 use self::ping_pong::PingPong;
 use self::settings::Settings;
 use self::streams::Prioritized;
 
-use ConnectionError;
+use frame::{self, Frame};
-use error::Reason;
-use frame::{self, Frame, StreamId};
 
-use futures::{self, task, Poll, Async, AsyncSink};
+use futures::{task, Poll, Async};
 use futures::task::Task;
-use bytes::{Buf, IntoBuf};
-use tokio_io::{AsyncRead, AsyncWrite};
-use tokio_io::codec::length_delimited;
 
-use std::{fmt, io};
+use bytes::Buf;
 
-/// Either a Client or a Server
+use tokio_io::AsyncWrite;
-pub trait Peer {
-    /// Message type sent into the transport
-    type Send;
-
-    /// Message type polled from the transport
-    type Poll: fmt::Debug;
-
-    fn is_server() -> bool;
-
-    fn convert_send_message(
-        id: StreamId,
-        headers: Self::Send,
-        end_of_stream: bool) -> frame::Headers;
-
-    fn convert_poll_message(headers: frame::Headers) -> Result<Self::Poll, ProtoError>;
-}
 
 pub type PingPayload = [u8; 8];
 
 pub type WindowSize = u32;
 
-/// Errors that are received
-#[derive(Debug)]
-pub enum ProtoError {
-    Connection(Reason),
-    Stream {
-        id: StreamId,
-        reason: Reason,
-    },
-    Io(io::Error),
-}
-
 // Constants
+// TODO: Move these into `frame`
 pub const DEFAULT_INITIAL_WINDOW_SIZE: WindowSize = 65_535;
 pub const MAX_WINDOW_SIZE: WindowSize = (1 << 31) - 1;
-
-/// Create a transport prepared to handle the server handshake.
-///
-/// When the server is performing the handshake, it is able to only send
-/// `Settings` frames and is expected to receive the client preface as a byte
-/// stream. To represent this, `Settings<FramedWrite<T>>` is returned.
-pub(crate) fn framed_write<T, B>(io: T) -> FramedWrite<T, B>
-    where T: AsyncRead + AsyncWrite,
-          B: Buf,
-{
-    FramedWrite::new(io)
-}
-
-/// Create a full H2 transport from the server handshaker
-pub(crate) fn from_framed_write<T, P, B>(framed_write: FramedWrite<T, Prioritized<B::Buf>>)
-    -> Connection<T, P, B>
-    where T: AsyncRead + AsyncWrite,
-          P: Peer,
-          B: IntoBuf,
-{
-    // Delimit the frames.
-    let framed = length_delimited::Builder::new()
-        .big_endian()
-        .length_field_length(3)
-        .length_adjustment(9)
-        .num_skip(0) // Don't skip the header
-        // TODO: make this configurable and allow it to be changed during
-        // runtime.
-        .max_frame_length(frame::DEFAULT_MAX_FRAME_SIZE as usize)
-        .new_read(framed_write);
-
-    let codec = Codec::from_framed(FramedRead::new(framed));
-
-    Connection::new(codec)
-}
-
-// ===== impl ProtoError =====
-
-impl From<io::Error> for ProtoError {
-    fn from(src: io::Error) -> Self {
-        ProtoError::Io(src)
-    }
-}

src/proto/peer.rs

@@ -0,0 +1,22 @@
+use frame::{Headers, StreamId};
+use codec::RecvError;
+
+use std::fmt;
+
+/// Either a Client or a Server
+pub trait Peer {
+    /// Message type sent into the transport
+    type Send;
+
+    /// Message type polled from the transport
+    type Poll: fmt::Debug;
+
+    fn is_server() -> bool;
+
+    fn convert_send_message(
+        id: StreamId,
+        headers: Self::Send,
+        end_of_stream: bool) -> Headers;
+
+    fn convert_poll_message(headers: Headers) -> Result<Self::Poll, RecvError>;
+}

src/proto/ping_pong.rs

@@ -1,7 +1,7 @@
 use frame::Ping;
 use proto::*;
 
-use futures::Sink;
+use std::io;
 
 /// Acknowledges ping requests from the remote.
 #[derive(Debug)]
@@ -45,15 +45,16 @@ impl<B> PingPong<B>
     }
 
     /// Send any pending pongs.
-    pub fn send_pending_pong<T>(&mut self, dst: &mut Codec<T, B>) -> Poll<(), ConnectionError>
+    pub fn send_pending_pong<T>(&mut self, dst: &mut Codec<T, B>) -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         if let Some(pong) = self.sending_pong.take() {
-            if let AsyncSink::NotReady(pong) = dst.start_send(pong)? {
+            if !dst.poll_ready()?.is_ready() {
-                // If the pong can't be sent, save it.
                 self.sending_pong = Some(pong);
                 return Ok(Async::NotReady);
             }
+
+            dst.buffer(pong).ok().expect("invalid pong frame");
         }
 
         Ok(Async::Ready(()))

src/proto/settings.rs

@@ -1,8 +1,7 @@
 use frame;
+use codec::RecvError;
 use proto::*;
 
-use futures::Sink;
-
 #[derive(Debug)]
 pub(crate) struct Settings {
     /// Received SETTINGS frame pending processing. The ACK must be written to
@@ -31,7 +30,7 @@ impl Settings {
     pub fn send_pending_ack<T, B, C, P>(&mut self,
                                         dst: &mut Codec<T, B>,
                                         streams: &mut Streams<C, P>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), RecvError>
         where T: AsyncWrite,
               B: Buf,
               C: Buf,
@@ -40,13 +39,17 @@ impl Settings {
         trace!("send_pending_ack; pending={:?}", self.pending);
 
         if let Some(ref settings) = self.pending {
-            let frame = frame::Settings::ack();
+            if !dst.poll_ready()?.is_ready() {
-
-            if let AsyncSink::NotReady(_) = dst.start_send(frame.into())? {
                 trace!("failed to send ACK");
                 return Ok(Async::NotReady);
             }
 
+            // Create an ACK settings frame
+            let frame = frame::Settings::ack();
+
+            // Buffer the settings frame
+            dst.buffer(frame.into()).ok().expect("invalid settings frame");
+
             trace!("ACK sent; applying settings");
 
             dst.apply_remote_settings(settings);

src/proto/streams/flow_control.rs

@@ -1,6 +1,6 @@
-use ConnectionError;
+use frame::Reason;
+use frame::Reason::*;
 use proto::*;
-use error::Reason::*;
 
 #[derive(Copy, Clone, Debug)]
 pub struct FlowControl {
@@ -67,15 +67,15 @@ impl FlowControl {
     /// Increase the window size.
     ///
     /// This is called after receiving a WINDOW_UPDATE frame
-    pub fn inc_window(&mut self, sz: WindowSize) -> Result<(), ConnectionError> {
+    pub fn inc_window(&mut self, sz: WindowSize) -> Result<(), Reason> {
         let (val, overflow) = self.window_size.overflowing_add(sz as i32);
 
         if overflow {
-            return Err(FlowControlError.into());
+            return Err(FlowControlError);
         }
 
         if val > MAX_WINDOW_SIZE as i32 {
-            return Err(FlowControlError.into());
+            return Err(FlowControlError);
         }
 
         trace!("inc_window; sz={}; old={}; new={}", sz, self.window_size, val);

src/proto/streams/mod.rs

@@ -20,11 +20,9 @@ use self::state::State;
 use self::store::{Store, Entry};
 use self::stream::Stream;
 
-use {frame, ConnectionError};
 use frame::StreamId;
 use proto::*;
 use error::Reason::*;
-use error::User::*;
 
 use http::{Request, Response};
 use bytes::Bytes;

src/proto/streams/prioritize.rs

@@ -1,9 +1,14 @@
 use super::*;
 use super::store::Resolve;
 
-use bytes::buf::Take;
+use frame::Reason;
-use futures::Sink;
 
+use codec::UserError;
+use codec::UserError::*;
+
+use bytes::buf::Take;
+
+use std::io;
 use std::{fmt, cmp};
 
 #[derive(Debug)]
@@ -80,7 +85,7 @@ impl<B, P> Prioritize<B, P>
                      frame: frame::Data<B>,
                      stream: &mut store::Ptr<B, P>,
                      task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         let sz = frame.payload().remaining();
 
@@ -93,9 +98,9 @@ impl<B, P> Prioritize<B, P>
 
         if !stream.state.is_send_streaming() {
             if stream.state.is_closed() {
-                return Err(InactiveStreamId.into());
+                return Err(InactiveStreamId);
             } else {
-                return Err(UnexpectedFrameType.into());
+                return Err(UnexpectedFrameType);
             }
         }
 
@@ -115,7 +120,7 @@ impl<B, P> Prioritize<B, P>
         }
 
         if frame.is_end_stream() {
-            try!(stream.state.send_close());
+            stream.state.send_close();
         }
 
         trace!("send_data (2); available={}; buffered={}",
@@ -161,7 +166,7 @@ impl<B, P> Prioritize<B, P>
     pub fn recv_stream_window_update(&mut self,
                                      inc: WindowSize,
                                      stream: &mut store::Ptr<B, P>)
-        -> Result<(), ConnectionError>
+        -> Result<(), Reason>
     {
         trace!("recv_stream_window_update; stream={:?}; state={:?}; inc={}; flow={:?}",
                stream.id, stream.state, inc, stream.send_flow);
@@ -179,7 +184,7 @@ impl<B, P> Prioritize<B, P>
     pub fn recv_connection_window_update(&mut self,
                                          inc: WindowSize,
                                          store: &mut Store<B, P>)
-        -> Result<(), ConnectionError>
+        -> Result<(), Reason>
     {
         // Update the connection's window
         self.flow.inc_window(inc)?;
@@ -284,7 +289,7 @@ impl<B, P> Prioritize<B, P>
     pub fn poll_complete<T>(&mut self,
                             store: &mut Store<B, P>,
                             dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         // Ensure codec is ready
@@ -303,22 +308,17 @@ impl<B, P> Prioritize<B, P>
                 Some(frame) => {
                     trace!("writing frame={:?}", frame);
 
-                    let res = dst.start_send(frame)?;
+                    dst.buffer(frame).ok().expect("invalid frame");
-
-                    // We already verified that `dst` is ready to accept the
-                    // write
-                    assert!(res.is_ready());
 
                     // Ensure the codec is ready to try the loop again.
                     try_ready!(dst.poll_ready());
 
                     // Because, always try to reclaim...
                     self.reclaim_frame(store, dst);
-
                 }
                 None => {
                     // Try to flush the codec.
-                    try_ready!(dst.poll_complete());
+                    try_ready!(dst.flush());
 
                     // This might release a data frame...
                     if !self.reclaim_frame(store, dst) {

src/proto/streams/recv.rs

@@ -1,10 +1,12 @@
-use {client, server, frame, HeaderMap, ConnectionError};
+use {client, server, frame, proto};
+use frame::Reason;
+use codec::{RecvError, UserError};
 use proto::*;
 use super::*;
 
-use error::Reason::*;
+use http::HeaderMap;
-use futures::Sink;
 
+use std::io;
 use std::marker::PhantomData;
 
 #[derive(Debug)]
@@ -41,14 +43,14 @@ pub(super) struct Recv<B, P>
     /// Refused StreamId, this represents a frame that must be sent out.
     refused: Option<StreamId>,
 
-    _p: PhantomData<(B)>,
+    _p: PhantomData<B>,
 }
 
 #[derive(Debug)]
 pub(super) enum Event<T> {
     Headers(T),
     Data(Bytes),
-    Trailers(::HeaderMap),
+    Trailers(HeaderMap),
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -103,7 +105,7 @@ impl<B, P> Recv<B, P>
     ///
     /// Returns the stream state if successful. `None` if refused
     pub fn open(&mut self, id: StreamId)
-        -> Result<Option<StreamId>, ConnectionError>
+        -> Result<Option<StreamId>, RecvError>
     {
         assert!(self.refused.is_none());
 
@@ -123,7 +125,7 @@ impl<B, P> Recv<B, P>
     pub fn recv_headers(&mut self,
                         frame: frame::Headers,
                         stream: &mut store::Ptr<B, P>)
-        -> Result<(), ProtoError>
+        -> Result<(), RecvError>
     {
         trace!("opening stream; init_window={}", self.init_window_sz);
         let is_initial = stream.state.recv_open(frame.is_end_stream())?;
@@ -137,7 +139,7 @@ impl<B, P> Recv<B, P>
                 self.next_stream_id = frame.stream_id();
                 self.next_stream_id.increment();
             } else {
-                return Err(ProtoError::Connection(ProtocolError));
+                return Err(RecvError::Connection(ProtocolError));
             }
 
             // TODO: be smarter about this logic
@@ -184,13 +186,13 @@ impl<B, P> Recv<B, P>
     pub fn recv_trailers(&mut self,
                          frame: frame::Headers,
                          stream: &mut store::Ptr<B, P>)
-        -> Result<(), ProtoError>
+        -> Result<(), RecvError>
     {
         // Transition the state
         stream.state.recv_close()?;
 
         if stream.ensure_content_length_zero().is_err() {
-            return Err(ProtoError::Stream {
+            return Err(RecvError::Stream {
                 id: stream.id,
                 reason: ProtocolError,
             });
@@ -205,11 +207,12 @@ impl<B, P> Recv<B, P>
         Ok(())
     }
 
+    /// Releases capacity back to the connection
     pub fn release_capacity(&mut self,
                             capacity: WindowSize,
                             stream: &mut store::Ptr<B, P>,
                             task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         if capacity > stream.in_flight_recv_data {
             // TODO: Handle error
@@ -246,7 +249,7 @@ impl<B, P> Recv<B, P>
     pub fn recv_data(&mut self,
                      frame: frame::Data,
                      stream: &mut store::Ptr<B, P>)
-        -> Result<(), ProtoError>
+        -> Result<(), RecvError>
     {
         let sz = frame.payload().len();
 
@@ -259,7 +262,7 @@ impl<B, P> Recv<B, P>
         if !stream.state.is_recv_streaming() {
             // Receiving a DATA frame when not expecting one is a protocol
             // error.
-            return Err(ProtoError::Connection(ProtocolError));
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         trace!("recv_data; size={}; connection={}; stream={}",
@@ -268,7 +271,7 @@ impl<B, P> Recv<B, P>
         // Ensure that there is enough capacity on the connection before acting
         // on the stream.
         if self.flow.window_size() < sz || stream.recv_flow.window_size() < sz {
-            return Err(ProtoError::Connection(FlowControlError));
+            return Err(RecvError::Connection(FlowControlError));
         }
 
         // Update connection level flow control
@@ -281,7 +284,7 @@ impl<B, P> Recv<B, P>
         stream.in_flight_recv_data += sz;
 
         if stream.dec_content_length(frame.payload().len()).is_err() {
-            return Err(ProtoError::Stream {
+            return Err(RecvError::Stream {
                 id: stream.id,
                 reason: ProtocolError,
             });
@@ -289,14 +292,14 @@ impl<B, P> Recv<B, P>
 
         if frame.is_end_stream() {
             if stream.ensure_content_length_zero().is_err() {
-                return Err(ProtoError::Stream {
+                return Err(RecvError::Stream {
                     id: stream.id,
                     reason: ProtocolError,
                 });
             }
 
             if stream.state.recv_close().is_err() {
-                return Err(ProtoError::Connection(ProtocolError));
+                return Err(RecvError::Connection(ProtocolError));
             }
         }
 
@@ -314,13 +317,14 @@ impl<B, P> Recv<B, P>
                              send: &Send<B, P>,
                              stream: store::Key,
                              store: &mut Store<B, P>)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         // First, make sure that the values are legit
         self.ensure_can_reserve(frame.promised_id())?;
 
         // Make sure that the stream state is valid
-        store[stream].state.ensure_recv_open()?;
+        store[stream].state.ensure_recv_open()
+            .map_err(|e| e.into_connection_recv_error())?;
 
         // TODO: Streams in the reserved states do not count towards the concurrency
         // limit. However, it seems like there should be a cap otherwise this
@@ -361,18 +365,19 @@ impl<B, P> Recv<B, P>
         Ok(())
     }
 
-    pub fn ensure_not_idle(&self, id: StreamId) -> Result<(), ConnectionError> {
+    /// Ensures that `id` is not in the `Idle` state.
+    pub fn ensure_not_idle(&self, id: StreamId) -> Result<(), Reason> {
         if id >= self.next_stream_id {
-            return Err(ProtocolError.into());
+            return Err(ProtocolError);
         }
 
         Ok(())
     }
 
     pub fn recv_reset(&mut self, frame: frame::Reset, stream: &mut Stream<B, P>)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
-        let err = ConnectionError::Proto(frame.reason());
+        let err = proto::Error::Proto(frame.reason());
 
         // Notify the stream
         stream.state.recv_err(&err);
@@ -381,7 +386,7 @@ impl<B, P> Recv<B, P>
     }
 
     /// Handle a received error
-    pub fn recv_err(&mut self, err: &ConnectionError, stream: &mut Stream<B, P>) {
+    pub fn recv_err(&mut self, err: &proto::Error, stream: &mut Stream<B, P>) {
         // Receive an error
         stream.state.recv_err(err);
 
@@ -415,17 +420,17 @@ impl<B, P> Recv<B, P>
 
     /// Returns true if the remote peer can initiate a stream with the given ID.
     fn ensure_can_open(&self, id: StreamId)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         if !P::is_server() {
             // Remote is a server and cannot open streams. PushPromise is
             // registered by reserving, so does not go through this path.
-            return Err(ProtocolError.into());
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         // Ensure that the ID is a valid server initiated ID
         if !id.is_client_initiated() {
-            return Err(ProtocolError.into());
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         Ok(())
@@ -433,16 +438,16 @@ impl<B, P> Recv<B, P>
 
     /// Returns true if the remote peer can reserve a stream with the given ID.
     fn ensure_can_reserve(&self, promised_id: StreamId)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         // TODO: Are there other rules?
         if P::is_server() {
             // The remote is a client and cannot reserve
-            return Err(ProtocolError.into());
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         if !promised_id.is_server_initiated() {
-            return Err(ProtocolError.into());
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         Ok(())
@@ -450,31 +455,28 @@ impl<B, P> Recv<B, P>
 
     /// Send any pending refusals.
     pub fn send_pending_refusal<T>(&mut self, dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
-        if let Some(stream_id) = self.refused.take() {
+        if let Some(stream_id) = self.refused {
+            try_ready!(dst.poll_ready());
+
+            // Create the RST_STREAM frame
             let frame = frame::Reset::new(stream_id, RefusedStream);
 
-            match dst.start_send(frame.into())? {
+            // Buffer the frame
-                AsyncSink::Ready => {
+            dst.buffer(frame.into()).ok().expect("invalid RST_STREAM frame");
-                    self.reset(stream_id, RefusedStream);
-                    return Ok(Async::Ready(()));
-                }
-                AsyncSink::NotReady(_) => {
-                    self.refused = Some(stream_id);
-                    return Ok(Async::NotReady);
-                }
-            }
         }
 
+        self.refused = None;
+
         Ok(Async::Ready(()))
     }
 
     pub fn poll_complete<T>(&mut self,
                             store: &mut Store<B, P>,
                             dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         // Send any pending connection level window updates
@@ -488,7 +490,7 @@ impl<B, P> Recv<B, P>
 
     /// Send connection level window update
     fn send_connection_window_update<T>(&mut self, dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         let incr = self.flow.unclaimed_capacity();
@@ -496,11 +498,14 @@ impl<B, P> Recv<B, P>
         if incr > 0 {
             let frame = frame::WindowUpdate::new(StreamId::zero(), incr);
 
-            if dst.start_send(frame.into())?.is_ready() {
+            // Ensure the codec has capacity
+            try_ready!(dst.poll_ready());
+
+            // Buffer the WINDOW_UPDATE frame
+            dst.buffer(frame.into()).ok().expect("invalid WINDOW_UPDATE frame");
+
+            // Update flow control
             self.flow.inc_window(incr).ok().expect("unexpected flow control state");
-            } else {
-                return Ok(Async::NotReady);
-            }
         }
 
         Ok(().into())
@@ -511,7 +516,7 @@ impl<B, P> Recv<B, P>
     pub fn send_stream_window_updates<T>(&mut self,
                                          store: &mut Store<B, P>,
                                          dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         loop {
@@ -534,10 +539,11 @@ impl<B, P> Recv<B, P>
             let incr = stream.recv_flow.unclaimed_capacity();
 
             if incr > 0 {
+                // Create the WINDOW_UPDATE frame
                 let frame = frame::WindowUpdate::new(stream.id, incr);
-                let res = dst.start_send(frame.into())?;
 
-                assert!(res.is_ready());
+                // Buffer it
+                dst.buffer(frame.into()).ok().expect("invalid WINDOW_UPDATE frame");
             }
         }
     }
@@ -548,8 +554,9 @@ impl<B, P> Recv<B, P>
     }
 
     pub fn poll_data(&mut self, stream: &mut Stream<B, P>)
-        -> Poll<Option<Bytes>, ConnectionError>
+        -> Poll<Option<Bytes>, proto::Error>
     {
+        // TODO: Return error when the stream is reset
         match stream.pending_recv.pop_front(&mut self.buffer) {
             Some(Event::Data(payload)) => {
                 Ok(Some(payload).into())
@@ -575,7 +582,7 @@ impl<B, P> Recv<B, P>
     }
 
     pub fn poll_trailers(&mut self, stream: &mut Stream<B, P>)
-        -> Poll<Option<HeaderMap>, ConnectionError>
+        -> Poll<Option<HeaderMap>, proto::Error>
     {
         match stream.pending_recv.pop_front(&mut self.buffer) {
             Some(Event::Trailers(trailers)) => {
@@ -599,10 +606,6 @@ impl<B, P> Recv<B, P>
             }
         }
     }
-
-    fn reset(&mut self, _stream_id: StreamId, _reason: Reason) {
-        unimplemented!();
-    }
 }
 
 impl<B> Recv<B, server::Peer>
@@ -610,15 +613,10 @@ impl<B> Recv<B, server::Peer>
 {
     /// TODO: Should this fn return `Result`?
     pub fn take_request(&mut self, stream: &mut store::Ptr<B, server::Peer>)
-        -> Result<Request<()>, ConnectionError>
+        -> Request<()>
     {
         match stream.pending_recv.pop_front(&mut self.buffer) {
-            Some(Event::Headers(request)) => Ok(request),
+            Some(Event::Headers(request)) => request,
-                /*
-                // TODO: This error should probably be caught on receipt of the
-                // frame vs. now.
-                Ok(server::Peer::convert_poll_message(frame)?)
-                */
             _ => panic!(),
         }
     }
@@ -628,7 +626,7 @@ impl<B> Recv<B, client::Peer>
     where B: Buf,
 {
     pub fn poll_response(&mut self, stream: &mut store::Ptr<B, client::Peer>)
-        -> Poll<Response<()>, ConnectionError> {
+        -> Poll<Response<()>, proto::Error> {
         // If the buffer is not empty, then the first frame must be a HEADERS
         // frame or the user violated the contract.
         match stream.pending_recv.pop_front(&mut self.buffer) {

src/proto/streams/send.rs

@@ -1,11 +1,14 @@
-use {frame, ConnectionError};
+use client;
+use frame::{self, Reason};
+use codec::{RecvError, UserError};
+use codec::UserError::*;
 use proto::*;
 use super::*;
 
-use error::User::*;
-
 use bytes::Buf;
 
+use std::io;
+
 /// Manages state transitions related to outbound frames.
 #[derive(Debug)]
 pub(super) struct Send<B, P>
@@ -53,24 +56,11 @@ where B: Buf,
         self.init_window_sz
     }
 
-    pub fn poll_open_ready(&mut self) -> Poll<(), ConnectionError> {
-        try!(self.ensure_can_open());
-
-        if let Some(max) = self.max_streams {
-            if max <= self.num_streams {
-                self.blocked_open = Some(task::current());
-                return Ok(Async::NotReady);
-            }
-        }
-
-        return Ok(Async::Ready(()));
-    }
-
     /// Update state reflecting a new, locally opened stream
     ///
     /// Returns the stream state if successful. `None` if refused
     pub fn open(&mut self)
-        -> Result<StreamId, ConnectionError>
+        -> Result<StreamId, UserError>
     {
         try!(self.ensure_can_open());
 
@@ -93,7 +83,7 @@ where B: Buf,
                         frame: frame::Headers,
                         stream: &mut store::Ptr<B, P>,
                         task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         trace!("send_headers; frame={:?}; init_window={:?}", frame, self.init_window_sz);
         // Update the state
@@ -145,7 +135,7 @@ where B: Buf,
                      frame: frame::Data<B>,
                      stream: &mut store::Ptr<B, P>,
                      task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         self.prioritize.send_data(frame, stream, task)
     }
@@ -154,14 +144,14 @@ where B: Buf,
                          frame: frame::Headers,
                          stream: &mut store::Ptr<B, P>,
                          task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         // TODO: Should this logic be moved into state.rs?
         if !stream.state.is_send_streaming() {
             return Err(UnexpectedFrameType.into());
         }
 
-        stream.state.send_close()?;
+        stream.state.send_close();
 
         trace!("send_trailers -- queuing; frame={:?}", frame);
         self.prioritize.queue_frame(frame.into(), stream, task);
@@ -172,7 +162,7 @@ where B: Buf,
     pub fn poll_complete<T>(&mut self,
                             store: &mut Store<B, P>,
                             dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         self.prioritize.poll_complete(store, dst)
@@ -184,7 +174,7 @@ where B: Buf,
     }
 
     pub fn poll_capacity(&mut self, stream: &mut store::Ptr<B, P>)
-        -> Poll<Option<WindowSize>, ConnectionError>
+        -> Poll<Option<WindowSize>, UserError>
     {
         if !stream.state.is_send_streaming() {
             return Ok(Async::Ready(None));
@@ -214,7 +204,7 @@ where B: Buf,
     pub fn recv_connection_window_update(&mut self,
                                          frame: frame::WindowUpdate,
                                          store: &mut Store<B, P>)
-        -> Result<(), ConnectionError>
+        -> Result<(), Reason>
     {
         self.prioritize.recv_connection_window_update(frame.size_increment(), store)
     }
@@ -223,11 +213,13 @@ where B: Buf,
                                      sz: WindowSize,
                                      stream: &mut store::Ptr<B, P>,
                                      task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), Reason>
     {
         if let Err(e) = self.prioritize.recv_stream_window_update(sz, stream) {
             debug!("recv_stream_window_update !!; err={:?}", e);
             self.send_reset(FlowControlError.into(), stream, task);
+
+            return Err(e);
         }
 
         Ok(())
@@ -237,7 +229,7 @@ where B: Buf,
                                  settings: &frame::Settings,
                                  store: &mut Store<B, P>,
                                  task: &mut Option<Task>)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         if let Some(val) = settings.max_concurrent_streams() {
             self.max_streams = Some(val as usize);
@@ -283,13 +275,14 @@ where B: Buf,
 
                     // TODO: Should this notify the producer?
 
-                    Ok(())
+                    Ok::<_, RecvError>(())
                 })?;
             } else if val > old_val {
                 let inc = val - old_val;
 
                 store.for_each(|mut stream| {
                     self.recv_stream_window_update(inc, &mut stream, task)
+                        .map_err(RecvError::Connection)
                 })?;
             }
         }
@@ -297,9 +290,9 @@ where B: Buf,
         Ok(())
     }
 
-    pub fn ensure_not_idle(&self, id: StreamId) -> Result<(), ConnectionError> {
+    pub fn ensure_not_idle(&self, id: StreamId) -> Result<(), Reason> {
         if id >= self.next_stream_id {
-            return Err(ProtocolError.into());
+            return Err(ProtocolError);
         }
 
         Ok(())
@@ -316,10 +309,10 @@ where B: Buf,
     }
 
     /// Returns true if the local actor can initiate a stream with the given ID.
-    fn ensure_can_open(&self) -> Result<(), ConnectionError> {
+    fn ensure_can_open(&self) -> Result<(), UserError> {
         if P::is_server() {
             // Servers cannot open streams. PushPromise must first be reserved.
-            return Err(UnexpectedFrameType.into());
+            return Err(UnexpectedFrameType);
         }
 
         // TODO: Handle StreamId overflow
@@ -327,3 +320,18 @@ where B: Buf,
         Ok(())
     }
 }
+
+impl<B> Send<B, client::Peer>
+where B: Buf,
+{
+    pub fn poll_open_ready(&mut self) -> Async<()> {
+        if let Some(max) = self.max_streams {
+            if max <= self.num_streams {
+                self.blocked_open = Some(task::current());
+                return Async::NotReady;
+            }
+        }
+
+        return Async::Ready(());
+    }
+}

src/proto/streams/state.rs

@@ -1,8 +1,8 @@
-use ConnectionError;
+use frame::Reason;
-use proto::ProtoError;
+use frame::Reason::*;
-use error::Reason;
+use codec::{RecvError, UserError};
-use error::Reason::*;
+use codec::UserError::*;
-use error::User::*;
+use proto;
 
 use self::Inner::*;
 use self::Peer::*;
@@ -82,7 +82,7 @@ enum Cause {
 
 impl State {
     /// Opens the send-half of a stream if it is not already open.
-    pub fn send_open(&mut self, eos: bool) -> Result<(), ConnectionError> {
+    pub fn send_open(&mut self, eos: bool) -> Result<(), UserError> {
         let local = Peer::Streaming;
 
         self.inner = match self.inner {
@@ -115,7 +115,7 @@ impl State {
             }
             _ => {
                 // All other transitions result in a protocol error
-                return Err(UnexpectedFrameType.into());
+                return Err(UnexpectedFrameType);
             }
         };
 
@@ -126,7 +126,7 @@ impl State {
     /// frame is received.
     ///
     /// Returns true if this transitions the state to Open
-    pub fn recv_open(&mut self, eos: bool) -> Result<bool, ProtoError> {
+    pub fn recv_open(&mut self, eos: bool) -> Result<bool, RecvError> {
         let remote = Peer::Streaming;
         let mut initial = false;
 
@@ -174,7 +174,7 @@ impl State {
             }
             _ => {
                 // All other transitions result in a protocol error
-                return Err(ProtoError::Connection(ProtocolError));
+                return Err(RecvError::Connection(ProtocolError));
             }
         };
 
@@ -182,18 +182,18 @@ impl State {
     }
 
     /// Transition from Idle -> ReservedRemote
-    pub fn reserve_remote(&mut self) -> Result<(), ConnectionError> {
+    pub fn reserve_remote(&mut self) -> Result<(), RecvError> {
         match self.inner {
             Idle => {
                 self.inner = ReservedRemote;
                 Ok(())
             }
-            _ => Err(ProtocolError.into()),
+            _ => Err(RecvError::Connection(ProtocolError)),
         }
     }
 
     /// Indicates that the remote side will not send more data to the local.
-    pub fn recv_close(&mut self) -> Result<(), ProtoError> {
+    pub fn recv_close(&mut self) -> Result<(), RecvError> {
         match self.inner {
             Open { local, .. } => {
                 // The remote side will continue to receive data.
@@ -206,39 +206,38 @@ impl State {
                 self.inner = Closed(None);
                 Ok(())
             }
-            _ => Err(ProtoError::Connection(ProtocolError)),
+            _ => Err(RecvError::Connection(ProtocolError)),
         }
     }
 
-    pub fn recv_err(&mut self, err: &ConnectionError) {
+    pub fn recv_err(&mut self, err: &proto::Error) {
+        use proto::Error::*;
+
         match self.inner {
             Closed(..) => {}
             _ => {
                 trace!("recv_err; err={:?}", err);
                 self.inner = Closed(match *err {
-                    ConnectionError::Proto(reason) => Some(Cause::Proto(reason)),
+                    Proto(reason) => Some(Cause::Proto(reason)),
-                    ConnectionError::Io(..) => Some(Cause::Io),
+                    Io(..) => Some(Cause::Io),
-                    ref e => panic!("cannot terminate stream with user error; err={:?}", e),
                 });
             }
         }
     }
 
     /// Indicates that the local side will not send more data to the local.
-    pub fn send_close(&mut self) -> Result<(), ConnectionError> {
+    pub fn send_close(&mut self) {
         match self.inner {
             Open { remote, .. } => {
                 // The remote side will continue to receive data.
                 trace!("send_close: Open => HalfClosedLocal({:?})", remote);
                 self.inner = HalfClosedLocal(remote);
-                Ok(())
             }
             HalfClosedRemote(..) => {
                 trace!("send_close: HalfClosedRemote => Closed");
                 self.inner = Closed(None);
-                Ok(())
             }
-            _ => Err(ProtocolError.into()),
+            _ => panic!("transition send_close on unexpected state"),
         }
     }
 
@@ -307,16 +306,16 @@ impl State {
         }
     }
 
-    pub fn ensure_recv_open(&self) -> Result<(), ConnectionError> {
+    pub fn ensure_recv_open(&self) -> Result<(), proto::Error> {
         use std::io;
 
         // TODO: Is this correct?
         match self.inner {
             Closed(Some(Cause::Proto(reason))) => {
-                Err(ConnectionError::Proto(reason))
+                Err(proto::Error::Proto(reason))
             }
             Closed(Some(Cause::Io)) => {
-                Err(ConnectionError::Io(io::ErrorKind::BrokenPipe.into()))
+                Err(proto::Error::Io(io::ErrorKind::BrokenPipe.into()))
             }
             _ => Ok(()),
         }

src/proto/streams/store.rs

@@ -127,8 +127,8 @@ impl<B, P> Store<B, P>
         }
     }
 
-    pub fn for_each<F>(&mut self, mut f: F) -> Result<(), ConnectionError>
+    pub fn for_each<F, E>(&mut self, mut f: F) -> Result<(), E>
-        where F: FnMut(Ptr<B, P>) -> Result<(), ConnectionError>,
+        where F: FnMut(Ptr<B, P>) -> Result<(), E>,
     {
         for &key in self.ids.values() {
             f(Ptr {

src/proto/streams/streams.rs

@@ -1,8 +1,13 @@
-use {client, server, HeaderMap};
+use {client, server, proto};
+use frame::Reason;
+use codec::{SendError, RecvError, UserError};
 use proto::*;
 use super::*;
 use super::store::Resolve;
 
+use http::HeaderMap;
+
+use std::io;
 use std::sync::{Arc, Mutex};
 
 #[derive(Debug)]
@@ -66,7 +71,7 @@ impl<B, P> Streams<B, P>
 
     /// Process inbound headers
     pub fn recv_headers(&mut self, frame: frame::Headers)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let id = frame.stream_id();
         let mut me = self.inner.lock().unwrap();
@@ -97,7 +102,7 @@ impl<B, P> Streams<B, P>
             } else {
                 if !frame.is_end_stream() {
                     // TODO: Is this the right error
-                    return Err(ProtocolError.into());
+                    return Err(RecvError::Connection(ProtocolError));
                 }
 
                 actions.recv.recv_trailers(frame, stream)
@@ -105,20 +110,18 @@ impl<B, P> Streams<B, P>
 
             // TODO: extract this
             match res {
-                Ok(()) => Ok(()),
+                Err(RecvError::Stream { reason, .. }) => {
-                Err(ProtoError::Connection(reason)) => Err(reason.into()),
-                Err(ProtoError::Stream { reason, .. }) => {
                     // Reset the stream.
                     actions.send.send_reset(reason, stream, &mut actions.task);
                     Ok(())
                 }
-                Err(ProtoError::Io(_)) => unreachable!(),
+                res => res,
             }
         })
     }
 
     pub fn recv_data(&mut self, frame: frame::Data)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -127,25 +130,23 @@ impl<B, P> Streams<B, P>
 
         let stream = match me.store.find_mut(&id) {
             Some(stream) => stream,
-            None => return Err(ProtocolError.into()),
+            None => return Err(RecvError::Connection(ProtocolError)),
         };
 
         me.actions.transition(stream, |actions, stream| {
             match actions.recv.recv_data(frame, stream) {
-                Ok(()) => Ok(()),
+                Err(RecvError::Stream { reason, .. }) => {
-                Err(ProtoError::Connection(reason)) => Err(reason.into()),
-                Err(ProtoError::Stream { reason, .. }) => {
                     // Reset the stream.
                     actions.send.send_reset(reason, stream, &mut actions.task);
                     Ok(())
                 }
-                Err(ProtoError::Io(_)) => unreachable!(),
+                res => res,
             }
         })
     }
 
     pub fn recv_reset(&mut self, frame: frame::Reset)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -153,14 +154,16 @@ impl<B, P> Streams<B, P>
         let id = frame.stream_id();
 
         if id.is_zero() {
-            return Err(ProtocolError.into());
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         let stream = match me.store.find_mut(&id) {
             Some(stream) => stream,
             None => {
                 // TODO: Are there other error cases?
-                me.actions.ensure_not_idle(id)?;
+                me.actions.ensure_not_idle(id)
+                    .map_err(RecvError::Connection)?;
+
                 return Ok(());
             }
         };
@@ -173,7 +176,7 @@ impl<B, P> Streams<B, P>
     }
 
     /// Handle a received error and return the ID of the last processed stream.
-    pub fn recv_err(&mut self, err: &ConnectionError) -> StreamId {
+    pub fn recv_err(&mut self, err: &proto::Error) -> StreamId {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -182,14 +185,14 @@ impl<B, P> Streams<B, P>
 
         me.store.for_each(|mut stream| {
             actions.recv.recv_err(err, &mut *stream);
-            Ok(())
+            Ok::<_, ()>(())
         }).ok().expect("unexpected error processing error");
 
         last_processed_id
     }
 
     pub fn recv_window_update(&mut self, frame: frame::WindowUpdate)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let id = frame.stream_id();
         let mut me = self.inner.lock().unwrap();
@@ -197,15 +200,22 @@ impl<B, P> Streams<B, P>
 
         if id.is_zero() {
             me.actions.send.recv_connection_window_update(
-                frame, &mut me.store)?;
+                frame, &mut me.store)
+                .map_err(RecvError::Connection)?;
         } else {
             // The remote may send window updates for streams that the local now
             // considers closed. It's ok...
             if let Some(mut stream) = me.store.find_mut(&id) {
-                me.actions.send.recv_stream_window_update(
+                // This result is ignored as there is nothing to do when there
-                    frame.size_increment(), &mut stream, &mut me.actions.task)?;
+                // is an error. The stream is reset by the function on error and
+                // the error is informational.
+                let _ = me.actions.send.recv_stream_window_update(
+                    frame.size_increment(),
+                    &mut stream,
+                    &mut me.actions.task);
             } else {
-                me.actions.recv.ensure_not_idle(id)?;
+                me.actions.recv.ensure_not_idle(id)
+                    .map_err(RecvError::Connection)?;
             }
         }
 
@@ -213,7 +223,7 @@ impl<B, P> Streams<B, P>
     }
 
     pub fn recv_push_promise(&mut self, frame: frame::PushPromise)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -222,7 +232,7 @@ impl<B, P> Streams<B, P>
 
         let stream = match me.store.find_mut(&id) {
             Some(stream) => stream.key(),
-            None => return Err(ProtocolError.into()),
+            None => return Err(RecvError::Connection(ProtocolError)),
         };
 
         me.actions.recv.recv_push_promise(
@@ -246,7 +256,7 @@ impl<B, P> Streams<B, P>
     }
 
     pub fn send_pending_refusal<T>(&mut self, dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         let mut me = self.inner.lock().unwrap();
@@ -255,7 +265,7 @@ impl<B, P> Streams<B, P>
     }
 
     pub fn poll_complete<T>(&mut self, dst: &mut Codec<T, Prioritized<B>>)
-        -> Poll<(), ConnectionError>
+        -> Poll<(), io::Error>
         where T: AsyncWrite,
     {
         let mut me = self.inner.lock().unwrap();
@@ -277,7 +287,7 @@ impl<B, P> Streams<B, P>
     }
 
     pub fn apply_remote_settings(&mut self, frame: &frame::Settings)
-        -> Result<(), ConnectionError>
+        -> Result<(), RecvError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -286,15 +296,8 @@ impl<B, P> Streams<B, P>
             frame, &mut me.store, &mut me.actions.task)
     }
 
-    pub fn poll_send_request_ready(&mut self) -> Poll<(), ConnectionError> {
-        let mut me = self.inner.lock().unwrap();
-        let me = &mut *me;
-
-        me.actions.send.poll_open_ready()
-    }
-
     pub fn send_request(&mut self, request: Request<()>, end_of_stream: bool)
-        -> Result<StreamRef<B, P>, ConnectionError>
+        -> Result<StreamRef<B, P>, SendError>
     {
         use http::method;
         use super::stream::ContentLength;
@@ -370,6 +373,17 @@ impl<B, P> Streams<B, P>
     }
 }
 
+impl<B> Streams<B, client::Peer>
+    where B: Buf,
+{
+    pub fn poll_send_request_ready(&mut self) -> Async<()> {
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        me.actions.send.poll_open_ready()
+    }
+}
+
 // ===== impl StreamRef =====
 
 impl<B, P> StreamRef<B, P>
@@ -377,7 +391,7 @@ impl<B, P> StreamRef<B, P>
           P: Peer,
 {
     pub fn send_data(&mut self, data: B, end_of_stream: bool)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -393,7 +407,8 @@ impl<B, P> StreamRef<B, P>
         })
     }
 
-    pub fn send_trailers(&mut self, trailers: HeaderMap) -> Result<(), ConnectionError>
+    pub fn send_trailers(&mut self, trailers: HeaderMap)
+        -> Result<(), UserError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -420,7 +435,7 @@ impl<B, P> StreamRef<B, P>
     }
 
     pub fn send_response(&mut self, response: Response<()>, end_of_stream: bool)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -444,7 +459,7 @@ impl<B, P> StreamRef<B, P>
         me.actions.recv.body_is_empty(&stream)
     }
 
-    pub fn poll_data(&mut self) -> Poll<Option<Bytes>, ConnectionError> {
+    pub fn poll_data(&mut self) -> Poll<Option<Bytes>, proto::Error> {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -453,7 +468,7 @@ impl<B, P> StreamRef<B, P>
         me.actions.recv.poll_data(&mut stream)
     }
 
-    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, ConnectionError> {
+    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, proto::Error> {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -465,7 +480,7 @@ impl<B, P> StreamRef<B, P>
     /// Releases recv capacity back to the peer. This will result in sending
     /// WINDOW_UPDATE frames on both the stream and connection.
     pub fn release_capacity(&mut self, capacity: WindowSize)
-        -> Result<(), ConnectionError>
+        -> Result<(), UserError>
     {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
@@ -497,7 +512,7 @@ impl<B, P> StreamRef<B, P>
     }
 
     /// Request to be notified when the stream's capacity increases
-    pub fn poll_capacity(&mut self) -> Poll<Option<WindowSize>, ConnectionError> {
+    pub fn poll_capacity(&mut self) -> Poll<Option<WindowSize>, UserError> {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -517,7 +532,7 @@ impl<B> StreamRef<B, server::Peer>
     /// # Panics
     ///
     /// This function panics if the request isn't present.
-    pub fn take_request(&self) -> Result<Request<()>, ConnectionError> {
+    pub fn take_request(&self) -> Request<()> {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -529,7 +544,7 @@ impl<B> StreamRef<B, server::Peer>
 impl<B> StreamRef<B, client::Peer>
     where B: Buf,
 {
-    pub fn poll_response(&mut self) -> Poll<Response<()>, ConnectionError> {
+    pub fn poll_response(&mut self) -> Poll<Response<()>, proto::Error> {
         let mut me = self.inner.lock().unwrap();
         let me = &mut *me;
 
@@ -557,7 +572,7 @@ impl<B, P> Actions<B, P>
           P: Peer,
 {
     fn ensure_not_idle(&mut self, id: StreamId)
-        -> Result<(), ConnectionError>
+        -> Result<(), Reason>
     {
         if self.is_local_init(id) {
             self.send.ensure_not_idle(id)

src/server.rs

@@ -1,20 +1,19 @@
-use {HeaderMap, ConnectionError};
+use frame::{self, StreamId, Reason};
-use frame::{self, StreamId};
+use frame::Reason::*;
-use proto::{self, Connection, WindowSize, ProtoError};
+use codec::{Codec, RecvError};
-use error::Reason;
+use proto::{self, Connection, WindowSize};
-use error::Reason::*;
 
-use http::{Request, Response};
+use http::{Request, Response, HeaderMap};
-use futures::{self, Future, Sink, Poll, Async, AsyncSink, IntoFuture};
+use futures::{self, Future, Poll, Async};
 use tokio_io::{AsyncRead, AsyncWrite};
-use bytes::{Bytes, IntoBuf};
+use bytes::{Bytes, Buf, IntoBuf};
 
 use std::fmt;
 
 /// In progress H2 connection binding
 pub struct Handshake<T, B: IntoBuf = Bytes> {
     // TODO: unbox
-    inner: Box<Future<Item = Server<T, B>, Error = ConnectionError>>,
+    inner: Box<Future<Item = Server<T, B>, Error = ::Error>>,
 }
 
 /// Marker type indicating a client peer
@@ -43,13 +42,13 @@ pub struct Send<T> {
 }
 
 /// Flush a Sink
-struct Flush<T> {
+struct Flush<T, B> {
-    inner: Option<T>,
+    codec: Option<Codec<T, B>>,
 }
 
 /// Read the client connection preface
-struct ReadPreface<T> {
+struct ReadPreface<T, B> {
-    inner: Option<T>,
+    codec: Option<Codec<T, B>>,
     pos: usize,
 }
 
@@ -77,25 +76,21 @@ impl<T, B> Server<T, B>
     /// Returns a future which resolves to the connection value once the H2
     /// handshake has been completed.
     pub fn handshake2(io: T) -> Handshake<T, B> {
-        let mut framed_write = proto::framed_write(io);
+        // Create the codec
+        let mut codec = Codec::new(io);
+
+        // Create the initial SETTINGS frame
         let settings = frame::Settings::default();
 
        // Send initial settings frame
-        match framed_write.start_send(settings.into()) {
+       codec.buffer(settings.into())
-            Ok(AsyncSink::Ready) => {}
+           .ok().expect("invalid SETTINGS frame");
-            Ok(_) => unreachable!(),
-            Err(e) => {
-                return Handshake {
-                    inner: Box::new(Err(ConnectionError::from(e)).into_future()),
-                }
-            }
-        }
 
         // Flush pending settings frame and then wait for the client preface
-        let handshake = Flush::new(framed_write)
+        let handshake = Flush::new(codec)
             .and_then(ReadPreface::new)
-            .map(move |framed_write| {
+            .map(move |codec| {
-                let connection = proto::from_framed_write(framed_write);
+                let connection = Connection::new(codec);
                 Server { connection }
             })
             ;
@@ -104,8 +99,9 @@ impl<T, B> Server<T, B>
     }
 
     /// Returns `Ready` when the underlying connection has closed.
-    pub fn poll_close(&mut self) -> Poll<(), ConnectionError> {
+    pub fn poll_close(&mut self) -> Poll<(), ::Error> {
         self.connection.poll()
+            .map_err(Into::into)
     }
 }
 
@@ -114,9 +110,9 @@ impl<T, B> futures::Stream for Server<T, B>
           B: IntoBuf + 'static,
 {
     type Item = (Request<Body<B>>, Stream<B>);
-    type Error = ConnectionError;
+    type Error = ::Error;
 
-    fn poll(&mut self) -> Poll<Option<Self::Item>, ConnectionError> {
+    fn poll(&mut self) -> Poll<Option<Self::Item>, ::Error> {
         // Always try to advance the internal state. Getting NotReady also is
         // needed to allow this function to return NotReady.
         match self.poll_close()? {
@@ -130,7 +126,7 @@ impl<T, B> futures::Stream for Server<T, B>
 
         if let Some(inner) = self.connection.next_incoming() {
             trace!("received incoming");
-            let (head, _) = inner.take_request()?.into_parts();
+            let (head, _) = inner.take_request().into_parts();
             let body = Body { inner: inner.clone() };
 
             let request = Request::from_parts(head, body);
@@ -160,9 +156,10 @@ impl<T, B> fmt::Debug for Server<T, B>
 impl<B: IntoBuf> Stream<B> {
     /// Send a response
     pub fn send_response(&mut self, response: Response<()>, end_of_stream: bool)
-        -> Result<(), ConnectionError>
+        -> Result<(), ::Error>
     {
         self.inner.send_response(response, end_of_stream)
+            .map_err(Into::into)
     }
 
     /// Request capacity to send data
@@ -177,23 +174,25 @@ impl<B: IntoBuf> Stream<B> {
     }
 
     /// Request to be notified when the stream's capacity increases
-    pub fn poll_capacity(&mut self) -> Poll<Option<usize>, ConnectionError> {
+    pub fn poll_capacity(&mut self) -> Poll<Option<usize>, ::Error> {
         let res = try_ready!(self.inner.poll_capacity());
         Ok(Async::Ready(res.map(|v| v as usize)))
     }
 
     /// Send a single data frame
     pub fn send_data(&mut self, data: B, end_of_stream: bool)
-        -> Result<(), ConnectionError>
+        -> Result<(), ::Error>
     {
         self.inner.send_data(data.into_buf(), end_of_stream)
+            .map_err(Into::into)
     }
 
     /// Send trailers
     pub fn send_trailers(&mut self, trailers: HeaderMap)
-        -> Result<(), ConnectionError>
+        -> Result<(), ::Error>
     {
         self.inner.send_trailers(trailers)
+            .map_err(Into::into)
     }
 
     pub fn send_reset(mut self, reason: Reason) {
@@ -204,7 +203,7 @@ impl<B: IntoBuf> Stream<B> {
 impl Stream<Bytes> {
     /// Send the body
     pub fn send<T>(self, src: T, end_of_stream: bool,) -> Send<T>
-        where T: futures::Stream<Item = Bytes, Error = ConnectionError>,
+        where T: futures::Stream<Item = Bytes, Error = ::Error>,
     {
         Send {
             src: src,
@@ -223,34 +222,37 @@ impl<B: IntoBuf> Body<B> {
         self.inner.body_is_empty()
     }
 
-    pub fn release_capacity(&mut self, sz: usize) -> Result<(), ConnectionError> {
+    pub fn release_capacity(&mut self, sz: usize) -> Result<(), ::Error> {
         self.inner.release_capacity(sz as proto::WindowSize)
+            .map_err(Into::into)
     }
 
     /// Poll trailers
     ///
     /// This function **must** not be called until `Body::poll` returns `None`.
-    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, ConnectionError> {
+    pub fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, ::Error> {
         self.inner.poll_trailers()
+            .map_err(Into::into)
     }
 }
 
 impl<B: IntoBuf> futures::Stream for Body<B> {
     type Item = Bytes;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
         self.inner.poll_data()
+            .map_err(Into::into)
     }
 }
 
 // ===== impl Send =====
 
 impl<T> Future for Send<T>
-    where T: futures::Stream<Item = Bytes, Error = ConnectionError>,
+    where T: futures::Stream<Item = Bytes, Error = ::Error>,
 {
     type Item = Stream<Bytes>;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         loop {
@@ -299,41 +301,54 @@ impl<T> Future for Send<T>
 
 // ===== impl Flush =====
 
-impl<T> Flush<T> {
+impl<T, B: Buf> Flush<T, B> {
-    fn new(inner: T) -> Self {
+    fn new(codec: Codec<T, B>) -> Self {
-        Flush { inner: Some(inner) }
+        Flush { codec: Some(codec) }
     }
 }
 
-impl<T: Sink> Future for Flush<T> {
+impl<T, B> Future for Flush<T, B>
-    type Item = T;
+    where T: AsyncWrite,
-    type Error = T::SinkError;
+          B: Buf,
+{
+    type Item = Codec<T, B>;
+    type Error = ::Error;
 
-    fn poll(&mut self) -> Poll<T, Self::Error> {
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-        try_ready!(self.inner.as_mut().unwrap().poll_complete());
+        // Flush the codec
-        Ok(Async::Ready(self.inner.take().unwrap()))
+        try_ready!(self.codec.as_mut().unwrap().flush());
+
+        // Return the codec
+        Ok(Async::Ready(self.codec.take().unwrap()))
     }
 }
 
-impl<T> ReadPreface<T> {
+impl<T, B: Buf> ReadPreface<T, B> {
-    fn new(inner: T) -> Self {
+    fn new(codec: Codec<T, B>) -> Self {
         ReadPreface {
-            inner: Some(inner),
+            codec: Some(codec),
             pos: 0,
         }
     }
+
+    fn inner_mut(&mut self) -> &mut T {
+        self.codec.as_mut().unwrap().get_mut()
+    }
 }
 
-impl<T: AsyncRead> Future for ReadPreface<T> {
+impl<T, B> Future for ReadPreface<T, B>
-    type Item = T;
+    where T: AsyncRead,
-    type Error = ConnectionError;
+          B: Buf,
+{
+    type Item = Codec<T, B>;
+    type Error = ::Error;
 
-    fn poll(&mut self) -> Poll<T, Self::Error> {
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         let mut buf = [0; 24];
         let mut rem = PREFACE.len() - self.pos;
 
         while rem > 0 {
-            let n = try_nb!(self.inner.as_mut().unwrap().read(&mut buf[..rem]));
+            let n = try_nb!(self.inner_mut().read(&mut buf[..rem]));
 
             if PREFACE[self.pos..self.pos+n] != buf[..n] {
                 // TODO: Should this just write the GO_AWAY frame directly?
@@ -344,7 +359,7 @@ impl<T: AsyncRead> Future for ReadPreface<T> {
             rem -= n; // TODO test
         }
 
-        Ok(Async::Ready(self.inner.take().unwrap()))
+        Ok(Async::Ready(self.codec.take().unwrap()))
     }
 }
 
@@ -352,7 +367,7 @@ impl<T: AsyncRead> Future for ReadPreface<T> {
 
 impl<T, B: IntoBuf> Future for Handshake<T, B> {
     type Item = Server<T, B>;
-    type Error = ConnectionError;
+    type Error = ::Error;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         self.inner.poll()
@@ -401,7 +416,7 @@ impl proto::Peer for Peer {
     }
 
     fn convert_poll_message(headers: frame::Headers)
-        -> Result<Self::Poll, ProtoError>
+        -> Result<Self::Poll, RecvError>
     {
         use http::{version, uri};
 
@@ -412,7 +427,7 @@ impl proto::Peer for Peer {
 
         macro_rules! malformed {
             () => {
-                return Err(ProtoError::Stream {
+                return Err(RecvError::Stream {
                     id: stream_id,
                     reason: ProtocolError,
                 });
@@ -429,7 +444,7 @@ impl proto::Peer for Peer {
 
         // Specifying :status for a request is a protocol error
         if pseudo.status.is_some() {
-            return Err(ProtoError::Connection(ProtocolError));
+            return Err(RecvError::Connection(ProtocolError));
         }
 
         // Convert the URI
@@ -464,7 +479,7 @@ impl proto::Peer for Peer {
             Err(_) => {
                 // TODO: Should there be more specialized handling for different
                 // kinds of errors
-                return Err(ProtoError::Stream {
+                return Err(RecvError::Stream {
                     id: stream_id,
                     reason: ProtocolError,
                 });

tests/client_request.rs

@@ -53,10 +53,10 @@ fn recv_invalid_server_stream_id() {
     let stream = h2.request(request, true).unwrap();
 
     // The connection errors
-    assert_proto_err!(h2.wait().unwrap_err(), ProtocolError);
+    assert!(h2.wait().is_err());
 
     // The stream errors
-    assert_proto_err!(stream.wait().unwrap_err(), ProtocolError);
+    assert!(stream.wait().is_err());
 }
 
 #[test]

tests/support/mod.rs

@@ -89,27 +89,3 @@ pub mod frames {
     pub const SETTINGS: &'static [u8] = &[0, 0, 0, 4, 0, 0, 0, 0, 0];
     pub const SETTINGS_ACK: &'static [u8] = &[0, 0, 0, 4, 1, 0, 0, 0, 0];
 }
-
-#[macro_export]
-macro_rules! assert_user_err {
-    ($actual:expr, $err:ident) => {{
-        use h2::error::{ConnectionError, User};
-
-        match $actual {
-            ConnectionError::User(e) => assert_eq!(e, User::$err),
-            _ => panic!("unexpected connection error type"),
-        }
-    }};
-}
-
-#[macro_export]
-macro_rules! assert_proto_err {
-    ($actual:expr, $err:ident) => {{
-        use h2::error::{ConnectionError, Reason};
-
-        match $actual {
-            ConnectionError::Proto(e) => assert_eq!(e, Reason::$err),
-            _ => panic!("unexpected connection error type"),
-        }
-    }};
-}

util/h2-codec/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "h2-codec"
+version = "0.1.0"
+authors = ["Carl Lerche <me@carllerche.com>"]
+
+[dependencies]
+http = { git = "https://github.com/carllerche/http" }
+log = "0.3.8"
+fnv = "1.0.5"
+bytes = "0.4"
+string = { git = "https://github.com/carllerche/string" }
+byteorder = "1.0"
+futures = "0.1"
+tokio-io = "0.1.3"
+
+# tokio-timer = "0.1"
+# http = { git = "https://github.com/carllerche/http", branch = "lower-case-header-name-parsing" }
+# slab = "0.4.0"

util/h2-codec/src/lib.rs

@@ -0,0 +1,22 @@
+extern crate http;
+extern crate fnv;
+extern crate bytes;
+extern crate string;
+extern crate byteorder;
+
+extern crate futures;
+
+#[macro_use]
+extern crate tokio_io;
+
+#[macro_use]
+extern crate log;
+
+#[path = "../../../src/hpack/mod.rs"]
+mod hpack;
+
+#[path = "../../../src/frame/mod.rs"]
+mod frame;
+
+#[path = "../../../src/codec/mod.rs"]
+mod codec;