Clean up framing protocol

src/client.rs

@@ -5,6 +5,7 @@ use std::sync::{Arc, Mutex};
 
 use arc_swap::ArcSwapOption;
 use async_trait::async_trait;
+use bytes::Bytes;
 use log::{debug, error, trace};
 
 use futures::channel::mpsc::{unbounded, UnboundedReceiver};
@@ -28,6 +29,7 @@ use crate::message::*;
 use crate::netapp::*;
 use crate::recv::*;
 use crate::send::*;
+use crate::stream::*;
 use crate::util::*;
 
 pub(crate) struct ClientConn {
@@ -155,24 +157,16 @@ impl ClientConn {
 					.with_kind(SpanKind::Client)
 					.start(&tracer);
 				let propagator = BinaryPropagator::new();
-				let telemetry_id = Some(propagator.to_bytes(span.span_context()).to_vec());
+				let telemetry_id: Bytes = propagator.to_bytes(span.span_context()).to_vec().into();
 			} else {
-				let telemetry_id: Option<Vec<u8>> = None;
+				let telemetry_id: Bytes = Bytes::new();
 			}
 		};
 
 		// Encode request
-		let body = req.msg_ser.unwrap().clone();
+		let req_enc = req.into_enc(prio, path.as_bytes().to_vec().into(), telemetry_id);
-		let stream = req.body.into_stream();
+		let req_msg_len = req_enc.msg.len();
-
+		let req_stream = req_enc.encode();
-		let request = QueryMessage {
-			prio,
-			path: path.as_bytes(),
-			telemetry_id,
-			body: &body[..],
-		};
-		let bytes = request.encode();
-		drop(body);
 
 		// Send request through
 		let (resp_send, resp_recv) = oneshot::channel();
@@ -181,17 +175,19 @@ impl ClientConn {
 			error!(
 				"Too many inflight requests! RequestID collision. Interrupting previous request."
 			);
-			if old_ch.send(unbounded().1).is_err() {
+			let _ = old_ch.send(unbounded().1);
-				debug!("Could not send empty response to collisionned request, probably because request was interrupted. Dropping response.");
-			}
 		}
 
-		trace!("request: query_send {}, {} bytes", id, bytes.len());
+		trace!(
+			"request: query_send {} (serialized message: {} bytes)",
+			id,
+			req_msg_len
+		);
 
 		#[cfg(feature = "telemetry")]
-		span.set_attribute(KeyValue::new("len_query", bytes.len() as i64));
+		span.set_attribute(KeyValue::new("len_query_msg", req_msg_len as i64));
 
-		query_send.send((id, prio, Framing::new(bytes, stream).into_stream()))?;
+		query_send.send((id, prio, req_stream))?;
 
 		cfg_if::cfg_if! {
 			if #[cfg(feature = "telemetry")] {
@@ -202,28 +198,10 @@ impl ClientConn {
 				let stream = resp_recv.await?;
 			}
 		}
-		let (resp, stream) = Framing::from_stream(stream).await?.into_parts();
 
-		if resp.is_empty() {
+		let resp_enc = RespEnc::decode(Box::pin(stream)).await?;
-			return Err(Error::Message(
+		trace!("request response {}", id);
-				"Response is 0 bytes, either a collision or a protocol error".into(),
+		Resp::from_enc(resp_enc)
-			));
-		}
-
-		trace!("request response {}: ", id);
-
-		let code = resp[0];
-		if code == 0 {
-			let ser_resp = rmp_serde::decode::from_read_ref(&resp[1..])?;
-			Ok(Resp {
-				_phantom: Default::default(),
-				msg: ser_resp,
-				body: BodyData::Stream(stream),
-			})
-		} else {
-			let msg = String::from_utf8(resp[1..].to_vec()).unwrap_or_default();
-			Err(Error::Remote(code, msg))
-		}
 	}
 }
 

src/endpoint.rs

@@ -158,12 +158,7 @@ pub(crate) type DynEndpoint = Box<dyn GenericEndpoint + Send + Sync>;
 
 #[async_trait]
 pub(crate) trait GenericEndpoint {
-	async fn handle(
+	async fn handle(&self, req_enc: ReqEnc, from: NodeID) -> Result<RespEnc, Error>;
-		&self,
-		buf: &[u8],
-		stream: ByteStream,
-		from: NodeID,
-	) -> Result<(Vec<u8>, Option<ByteStream>), Error>;
 	fn drop_handler(&self);
 	fn clone_endpoint(&self) -> DynEndpoint;
 }
@@ -180,30 +175,13 @@ where
 	M: Message + 'static,
 	H: StreamingEndpointHandler<M> + 'static,
 {
-	async fn handle(
+	async fn handle(&self, req_enc: ReqEnc, from: NodeID) -> Result<RespEnc, Error> {
-		&self,
-		buf: &[u8],
-		stream: ByteStream,
-		from: NodeID,
-	) -> Result<(Vec<u8>, Option<ByteStream>), Error> {
 		match self.0.handler.load_full() {
 			None => Err(Error::NoHandler),
 			Some(h) => {
-				let req = rmp_serde::decode::from_read_ref(buf)?;
+				let req = Req::from_enc(req_enc)?;
-				let req = Req {
-					_phantom: Default::default(),
-					msg: Arc::new(req),
-					msg_ser: None,
-					body: BodyData::Stream(stream),
-				};
 				let res = h.handle(req, from).await;
-				let Resp {
+				Ok(res.into_enc()?)
-					msg,
-					body,
-					_phantom,
-				} = res;
-				let res_bytes = rmp_to_vec_all_named(&msg)?;
-				Ok((res_bytes, body.into_stream()))
 			}
 		}
 	}

src/lib.rs

@@ -14,6 +14,7 @@
 //! Also check out the examples to learn how to use this crate.
 
 pub mod error;
+pub mod stream;
 pub mod util;
 
 pub mod endpoint;

src/message.rs

@@ -2,12 +2,13 @@ use std::fmt;
 use std::marker::PhantomData;
 use std::sync::Arc;
 
-use bytes::Bytes;
+use bytes::{BufMut, Bytes, BytesMut};
 use serde::{Deserialize, Serialize};
 
-use futures::stream::{Stream, StreamExt};
+use futures::stream::StreamExt;
 
 use crate::error::*;
+use crate::stream::*;
 use crate::util::*;
 
 /// Priority of a request (click to read more about priorities).
@@ -45,6 +46,15 @@ pub trait Message: Serialize + for<'de> Deserialize<'de> + Send + Sync {
 	type Response: Serialize + for<'de> Deserialize<'de> + Send + Sync;
 }
 
+// ----
+
+/// The Req<M> is a helper object used to create requests and attach them
+/// a streaming body. If the body is a fixed Bytes and not a ByteStream,
+/// Req<M> is cheaply clonable to allow the request to be sent to different
+/// peers (Clone will panic if the body is a ByteStream).
+///
+/// Internally, this is also used to encode and decode requests
+/// from/to byte streams to be sent over the network.
 pub struct Req<M: Message> {
 	pub(crate) _phantom: PhantomData<M>,
 	pub(crate) msg: Arc<M>,
@@ -52,30 +62,6 @@ pub struct Req<M: Message> {
 	pub(crate) body: BodyData,
 }
 
-pub struct Resp<M: Message> {
-	pub(crate) _phantom: PhantomData<M>,
-	pub(crate) msg: M::Response,
-	pub(crate) body: BodyData,
-}
-
-pub(crate) enum BodyData {
-	None,
-	Fixed(Bytes),
-	Stream(ByteStream),
-}
-
-impl BodyData {
-	pub fn into_stream(self) -> Option<ByteStream> {
-		match self {
-			BodyData::None => None,
-			BodyData::Fixed(b) => Some(Box::pin(futures::stream::once(async move { Ok(b) }))),
-			BodyData::Stream(s) => Some(s),
-		}
-	}
-}
-
-// ----
-
 impl<M: Message> Req<M> {
 	pub fn msg(&self) -> &M {
 		&self.msg
@@ -94,6 +80,31 @@ impl<M: Message> Req<M> {
 			..self
 		}
 	}
+
+	pub(crate) fn into_enc(
+		self,
+		prio: RequestPriority,
+		path: Bytes,
+		telemetry_id: Bytes,
+	) -> ReqEnc {
+		ReqEnc {
+			prio,
+			path,
+			telemetry_id,
+			msg: self.msg_ser.unwrap(),
+			stream: self.body.into_stream(),
+		}
+	}
+
+	pub(crate) fn from_enc(enc: ReqEnc) -> Result<Self, rmp_serde::decode::Error> {
+		let msg = rmp_serde::decode::from_read_ref(&enc.msg)?;
+		Ok(Req {
+			_phantom: Default::default(),
+			msg: Arc::new(msg),
+			msg_ser: Some(enc.msg),
+			body: enc.stream.map(BodyData::Stream).unwrap_or(BodyData::None),
+		})
+	}
 }
 
 pub trait IntoReq<M: Message> {
@@ -160,19 +171,14 @@ where
 	}
 }
 
-impl<M> fmt::Debug for Resp<M>
+// ----
-where
+
-	M: Message,
+/// The Resp<M> represents a full response from a RPC that may have
-	<M as Message>::Response: fmt::Debug,
+/// an attached body stream.
-{
+pub struct Resp<M: Message> {
-	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+	pub(crate) _phantom: PhantomData<M>,
-		write!(f, "Resp[{:?}", self.msg)?;
+	pub(crate) msg: M::Response,
-		match &self.body {
+	pub(crate) body: BodyData,
-			BodyData::None => write!(f, "]"),
-			BodyData::Fixed(b) => write!(f, "; body={}]", b.len()),
-			BodyData::Stream(_) => write!(f, "; body=stream]"),
-		}
-	}
 }
 
 impl<M: Message> Resp<M> {
@@ -205,160 +211,213 @@ impl<M: Message> Resp<M> {
 	pub fn into_msg(self) -> M::Response {
 		self.msg
 	}
+
+	pub(crate) fn into_enc(self) -> Result<RespEnc, rmp_serde::encode::Error> {
+		Ok(RespEnc::Success {
+			msg: rmp_to_vec_all_named(&self.msg)?.into(),
+			stream: self.body.into_stream(),
+		})
+	}
+
+	pub(crate) fn from_enc(enc: RespEnc) -> Result<Self, Error> {
+		match enc {
+			RespEnc::Success { msg, stream } => {
+				let msg = rmp_serde::decode::from_read_ref(&msg)?;
+				Ok(Self {
+					_phantom: Default::default(),
+					msg,
+					body: stream.map(BodyData::Stream).unwrap_or(BodyData::None),
+				})
+			}
+			RespEnc::Error { code, message } => Err(Error::Remote(code, message)),
+		}
+	}
+}
+
+impl<M> fmt::Debug for Resp<M>
+where
+	M: Message,
+	<M as Message>::Response: fmt::Debug,
+{
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+		write!(f, "Resp[{:?}", self.msg)?;
+		match &self.body {
+			BodyData::None => write!(f, "]"),
+			BodyData::Fixed(b) => write!(f, "; body={}]", b.len()),
+			BodyData::Stream(_) => write!(f, "; body=stream]"),
+		}
+	}
+}
+
+// ----
+
+pub(crate) enum BodyData {
+	None,
+	Fixed(Bytes),
+	Stream(ByteStream),
+}
+
+impl BodyData {
+	pub fn into_stream(self) -> Option<ByteStream> {
+		match self {
+			BodyData::None => None,
+			BodyData::Fixed(b) => Some(Box::pin(futures::stream::once(async move { Ok(b) }))),
+			BodyData::Stream(s) => Some(s),
+		}
+	}
 }
 
 // ---- ----
 
-pub(crate) struct QueryMessage<'a> {
+/// Encoding for requests into a ByteStream:
-	pub(crate) prio: RequestPriority,
-	pub(crate) path: &'a [u8],
-	pub(crate) telemetry_id: Option<Vec<u8>>,
-	pub(crate) body: &'a [u8],
-}
-
-/// QueryMessage encoding:
 /// - priority: u8
 /// - path length: u8
 /// - path: [u8; path length]
 /// - telemetry id length: u8
 /// - telemetry id: [u8; telemetry id length]
-/// - body [u8; ..]
+/// - msg len: u32
-impl<'a> QueryMessage<'a> {
+/// - msg [u8; ..]
-	pub(crate) fn encode(self) -> Vec<u8> {
+/// - the attached stream as the rest of the encoded stream
-		let tel_len = match &self.telemetry_id {
+pub(crate) struct ReqEnc {
-			Some(t) => t.len(),
+	pub(crate) prio: RequestPriority,
-			None => 0,
+	pub(crate) path: Bytes,
-		};
+	pub(crate) telemetry_id: Bytes,
+	pub(crate) msg: Bytes,
+	pub(crate) stream: Option<ByteStream>,
+}
 
-		let mut ret = Vec::with_capacity(10 + self.path.len() + tel_len + self.body.len());
+impl ReqEnc {
+	pub(crate) fn encode(self) -> ByteStream {
+		let mut buf = BytesMut::with_capacity(64);
 
-		ret.push(self.prio);
+		buf.put_u8(self.prio);
 
-		ret.push(self.path.len() as u8);
+		buf.put_u8(self.path.len() as u8);
-		ret.extend_from_slice(self.path);
+		buf.put(self.path);
 
-		if let Some(t) = self.telemetry_id {
+		buf.put_u8(self.telemetry_id.len() as u8);
-			ret.push(t.len() as u8);
+		buf.put(&self.telemetry_id[..]);
-			ret.extend(t);
+
+		buf.put_u32(self.msg.len() as u32);
+		buf.put(&self.msg[..]);
+
+		let header = buf.freeze();
+
+		if let Some(stream) = self.stream {
+			Box::pin(futures::stream::once(async move { Ok(header) }).chain(stream))
 		} else {
-			ret.push(0u8);
+			Box::pin(futures::stream::once(async move { Ok(header) }))
 		}
-
-		ret.extend_from_slice(self.body);
-
-		ret
 	}
 
-	pub(crate) fn decode(bytes: &'a [u8]) -> Result<Self, Error> {
+	pub(crate) async fn decode(stream: ByteStream) -> Result<Self, Error> {
-		if bytes.len() < 3 {
+		Self::decode_aux(stream).await.map_err(|_| Error::Framing)
-			return Err(Error::Message("Invalid protocol message".into()));
+	}
-		}
 
-		let path_length = bytes[1] as usize;
+	pub(crate) async fn decode_aux(stream: ByteStream) -> Result<Self, ReadExactError> {
-		if bytes.len() < 3 + path_length {
+		let mut reader = ByteStreamReader::new(stream);
-			return Err(Error::Message("Invalid protocol message".into()));
-		}
 
-		let telemetry_id_len = bytes[2 + path_length] as usize;
+		let prio = reader.read_u8().await?;
-		if bytes.len() < 3 + path_length + telemetry_id_len {
-			return Err(Error::Message("Invalid protocol message".into()));
-		}
 
-		let path = &bytes[2..2 + path_length];
+		let path_len = reader.read_u8().await?;
-		let telemetry_id = if telemetry_id_len > 0 {
+		let path = reader.read_exact(path_len as usize).await?;
-			Some(bytes[3 + path_length..3 + path_length + telemetry_id_len].to_vec())
-		} else {
-			None
-		};
 
-		let body = &bytes[3 + path_length + telemetry_id_len..];
+		let telemetry_id_len = reader.read_u8().await?;
+		let telemetry_id = reader.read_exact(telemetry_id_len as usize).await?;
+
+		let msg_len = reader.read_u32().await?;
+		let msg = reader.read_exact(msg_len as usize).await?;
 
 		Ok(Self {
-			prio: bytes[0],
+			prio,
 			path,
 			telemetry_id,
-			body,
+			msg,
+			stream: Some(reader.into_stream()),
 		})
 	}
 }
 
-// ---- ----
+/// Encoding for responses into a ByteStream:
-
+/// IF SUCCESS:
-pub(crate) struct Framing {
+/// - 0: u8
-	direct: Vec<u8>,
+/// - msg len: u32
-	stream: Option<ByteStream>,
+/// - msg [u8; ..]
+/// - the attached stream as the rest of the encoded stream
+/// IF ERROR:
+/// - message length + 1: u8
+/// - error code: u8
+/// - message: [u8; message_length]
+pub(crate) enum RespEnc {
+	Error {
+		code: u8,
+		message: String,
+	},
+	Success {
+		msg: Bytes,
+		stream: Option<ByteStream>,
+	},
 }
 
-impl Framing {
+impl RespEnc {
-	pub fn new(direct: Vec<u8>, stream: Option<ByteStream>) -> Self {
+	pub(crate) fn from_err(e: Error) -> Self {
-		assert!(direct.len() <= u32::MAX as usize);
+		RespEnc::Error {
-		Framing { direct, stream }
+			code: e.code(),
-	}
+			message: format!("{}", e),
-
-	pub fn into_stream(self) -> ByteStream {
-		use futures::stream;
-		let len = self.direct.len() as u32;
-		// required because otherwise the borrow-checker complains
-		let Framing { direct, stream } = self;
-
-		let res = stream::once(async move { Ok(u32::to_be_bytes(len).to_vec().into()) })
-			.chain(stream::once(async move { Ok(direct.into()) }));
-
-		if let Some(stream) = stream {
-			Box::pin(res.chain(stream))
-		} else {
-			Box::pin(res)
 		}
 	}
 
-	pub async fn from_stream<S: Stream<Item = Packet> + Unpin + Send + Sync + 'static>(
+	pub(crate) fn encode(self) -> ByteStream {
-		mut stream: S,
+		match self {
-	) -> Result<Self, Error> {
+			RespEnc::Success { msg, stream } => {
-		let mut packet = stream
+				let mut buf = BytesMut::with_capacity(64);
-			.next()
-			.await
-			.ok_or(Error::Framing)?
-			.map_err(|_| Error::Framing)?;
-		if packet.len() < 4 {
-			return Err(Error::Framing);
-		}
 
-		let mut len = [0; 4];
+				buf.put_u8(0);
-		len.copy_from_slice(&packet[..4]);
-		let len = u32::from_be_bytes(len);
-		packet = packet.slice(4..);
 
-		let mut buffer = Vec::new();
+				buf.put_u32(msg.len() as u32);
-		let len = len as usize;
+				buf.put(&msg[..]);
-		loop {
-			let max_cp = std::cmp::min(len - buffer.len(), packet.len());
 
-			buffer.extend_from_slice(&packet[..max_cp]);
+				let header = buf.freeze();
-			if buffer.len() == len {
+
-				packet = packet.slice(max_cp..);
+				if let Some(stream) = stream {
-				break;
+					Box::pin(futures::stream::once(async move { Ok(header) }).chain(stream))
+				} else {
+					Box::pin(futures::stream::once(async move { Ok(header) }))
+				}
+			}
+			RespEnc::Error { code, message } => {
+				let mut buf = BytesMut::with_capacity(64);
+				buf.put_u8(1 + message.len() as u8);
+				buf.put_u8(code);
+				buf.put(message.as_bytes());
+				let header = buf.freeze();
+				Box::pin(futures::stream::once(async move { Ok(header) }))
 			}
-			packet = stream
-				.next()
-				.await
-				.ok_or(Error::Framing)?
-				.map_err(|_| Error::Framing)?;
 		}
-
-		let stream: ByteStream = if packet.is_empty() {
-			Box::pin(stream)
-		} else {
-			Box::pin(futures::stream::once(async move { Ok(packet) }).chain(stream))
-		};
-
-		Ok(Framing {
-			direct: buffer,
-			stream: Some(stream),
-		})
 	}
 
-	pub fn into_parts(self) -> (Vec<u8>, ByteStream) {
+	pub(crate) async fn decode(stream: ByteStream) -> Result<Self, Error> {
-		let Framing { direct, stream } = self;
+		Self::decode_aux(stream).await.map_err(|_| Error::Framing)
-		(direct, stream.unwrap_or(Box::pin(futures::stream::empty())))
+	}
+
+	pub(crate) async fn decode_aux(stream: ByteStream) -> Result<Self, ReadExactError> {
+		let mut reader = ByteStreamReader::new(stream);
+
+		let is_err = reader.read_u8().await?;
+
+		if is_err > 0 {
+			let code = reader.read_u8().await?;
+			let message = reader.read_exact(is_err as usize - 1).await?;
+			let message = String::from_utf8(message.to_vec()).unwrap_or_default();
+			Ok(RespEnc::Error { code, message })
+		} else {
+			let msg_len = reader.read_u32().await?;
+			let msg = reader.read_exact(msg_len as usize).await?;
+
+			Ok(RespEnc::Success {
+				msg,
+				stream: Some(reader.into_stream()),
+			})
+		}
 	}
 }

src/recv.rs

@@ -10,7 +10,7 @@ use futures::AsyncReadExt;
 
 use crate::error::*;
 use crate::send::*;
-use crate::util::Packet;
+use crate::stream::*;
 
 /// Structure to warn when the sender is dropped before end of stream was reached, like when
 /// connection to some remote drops while transmitting data

src/send.rs

@@ -14,7 +14,7 @@ use tokio::sync::mpsc;
 
 use crate::error::*;
 use crate::message::*;
-use crate::util::{ByteStream, Packet};
+use crate::stream::*;
 
 // Messages are sent by chunks
 // Chunk format:

src/server.rs

@@ -28,6 +28,7 @@ use crate::message::*;
 use crate::netapp::*;
 use crate::recv::*;
 use crate::send::*;
+use crate::stream::*;
 use crate::util::*;
 
 // The client and server connection structs (client.rs and server.rs)
@@ -121,17 +122,12 @@ impl ServerConn {
 		Ok(())
 	}
 
-	async fn recv_handler_aux(
+	async fn recv_handler_aux(self: &Arc<Self>, req_enc: ReqEnc) -> Result<RespEnc, Error> {
-		self: &Arc<Self>,
+		let path = String::from_utf8(req_enc.path.to_vec())?;
-		bytes: &[u8],
-		stream: ByteStream,
-	) -> Result<(Vec<u8>, Option<ByteStream>), Error> {
-		let msg = QueryMessage::decode(bytes)?;
-		let path = String::from_utf8(msg.path.to_vec())?;
 
 		let handler_opt = {
 			let endpoints = self.netapp.endpoints.read().unwrap();
-			endpoints.get(&path).map(|e| e.clone_endpoint())
+			endpoints.get(&path[..]).map(|e| e.clone_endpoint())
 		};
 
 		if let Some(handler) = handler_opt {
@@ -139,9 +135,9 @@ impl ServerConn {
 				if #[cfg(feature = "telemetry")] {
 					let tracer = opentelemetry::global::tracer("netapp");
 
-					let mut span = if let Some(telemetry_id) = msg.telemetry_id {
+					let mut span = if !req_enc.telemetry_id.is_empty() {
 						let propagator = BinaryPropagator::new();
-						let context = propagator.from_bytes(telemetry_id);
+						let context = propagator.from_bytes(req_enc.telemetry_id.to_vec());
 						let context = Context::new().with_remote_span_context(context);
 						tracer.span_builder(format!(">> RPC {}", path))
 							.with_kind(SpanKind::Server)
@@ -156,13 +152,13 @@ impl ServerConn {
 							.start(&tracer)
 					};
 					span.set_attribute(KeyValue::new("path", path.to_string()));
-					span.set_attribute(KeyValue::new("len_query", msg.body.len() as i64));
+					span.set_attribute(KeyValue::new("len_query_msg", req_enc.msg.len() as i64));
 
-					handler.handle(msg.body, stream, self.peer_id)
+					handler.handle(req_enc, self.peer_id)
 						.with_context(Context::current_with_span(span))
 						.await
 				} else {
-					handler.handle(msg.body, stream, self.peer_id).await
+					handler.handle(req_enc, self.peer_id).await
 				}
 			}
 		} else {
@@ -181,32 +177,23 @@ impl RecvLoop for ServerConn {
 		let self2 = self.clone();
 		tokio::spawn(async move {
 			trace!("ServerConn recv_handler {}", id);
-			let (bytes, stream) = Framing::from_stream(stream).await?.into_parts();
+			let (prio, resp_enc) = match ReqEnc::decode(Box::pin(stream)).await {
+				Ok(req_enc) => {
+					let prio = req_enc.prio;
+					let resp = self2.recv_handler_aux(req_enc).await;
 
-			let prio = if !bytes.is_empty() { bytes[0] } else { 0u8 };
+					(prio, match resp {
-			let resp = self2.recv_handler_aux(&bytes[..], stream).await;
+						Ok(resp_enc) => resp_enc,
-
+						Err(e) => RespEnc::from_err(e),
-			let (resp_bytes, resp_stream) = match resp {
+					})
-				Ok((rb, rs)) => {
-					let mut resp_bytes = vec![0u8];
-					resp_bytes.extend(rb);
-					(resp_bytes, rs)
-				}
-				Err(e) => {
-					let mut resp_bytes = vec![e.code()];
-					resp_bytes.extend(e.to_string().into_bytes());
-					(resp_bytes, None)
 				}
+				Err(e) => (PRIO_NORMAL, RespEnc::from_err(e)),
 			};
 
 			trace!("ServerConn sending response to {}: ", id);
 
 			resp_send
-				.send((
+				.send((id, prio, resp_enc.encode()))
-					id,
-					prio,
-					Framing::new(resp_bytes, resp_stream).into_stream(),
-				))
 				.log_err("ServerConn recv_handler send resp bytes");
 			Ok::<_, Error>(())
 		});

src/stream.rs

@@ -0,0 +1,176 @@
+use std::collections::VecDeque;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+use bytes::Bytes;
+
+use futures::Future;
+use futures::{Stream, StreamExt};
+
+/// A stream of associated data.
+///
+/// When sent through Netapp, the Vec may be split in smaller chunk in such a way
+/// consecutive Vec may get merged, but Vec and error code may not be reordered
+///
+/// Error code 255 means the stream was cut before its end. Other codes have no predefined
+/// meaning, it's up to your application to define their semantic.
+pub type ByteStream = Pin<Box<dyn Stream<Item = Packet> + Send + Sync>>;
+
+pub type Packet = Result<Bytes, u8>;
+
+pub struct ByteStreamReader {
+	stream: ByteStream,
+	buf: VecDeque<Bytes>,
+	buf_len: usize,
+	eos: bool,
+	err: Option<u8>,
+}
+
+impl ByteStreamReader {
+	pub fn new(stream: ByteStream) -> Self {
+		ByteStreamReader {
+			stream,
+			buf: VecDeque::with_capacity(8),
+			buf_len: 0,
+			eos: false,
+			err: None,
+		}
+	}
+
+	pub fn read_exact(&mut self, read_len: usize) -> ByteStreamReadExact<'_> {
+		ByteStreamReadExact {
+			reader: self,
+			read_len,
+			fail_on_eos: true,
+		}
+	}
+
+	pub fn read_exact_or_eos(&mut self, read_len: usize) -> ByteStreamReadExact<'_> {
+		ByteStreamReadExact {
+			reader: self,
+			read_len,
+			fail_on_eos: false,
+		}
+	}
+
+	pub async fn read_u8(&mut self) -> Result<u8, ReadExactError> {
+		Ok(self.read_exact(1).await?[0])
+	}
+
+	pub async fn read_u16(&mut self) -> Result<u16, ReadExactError> {
+		let bytes = self.read_exact(2).await?;
+		let mut b = [0u8; 2];
+		b.copy_from_slice(&bytes[..]);
+		Ok(u16::from_be_bytes(b))
+	}
+
+	pub async fn read_u32(&mut self) -> Result<u32, ReadExactError> {
+		let bytes = self.read_exact(4).await?;
+		let mut b = [0u8; 4];
+		b.copy_from_slice(&bytes[..]);
+		Ok(u32::from_be_bytes(b))
+	}
+
+	pub fn into_stream(self) -> ByteStream {
+		let buf_stream = futures::stream::iter(self.buf.into_iter().map(Ok));
+		if let Some(err) = self.err {
+			Box::pin(buf_stream.chain(futures::stream::once(async move { Err(err) })))
+		} else if self.eos {
+			Box::pin(buf_stream)
+		} else {
+			Box::pin(buf_stream.chain(self.stream))
+		}
+	}
+
+	fn try_get(&mut self, read_len: usize) -> Option<Bytes> {
+		if self.buf_len >= read_len {
+			let mut slices = Vec::with_capacity(self.buf.len());
+			let mut taken = 0;
+			while taken < read_len {
+				let front = self.buf.pop_front().unwrap();
+				if taken + front.len() <= read_len {
+					taken += front.len();
+					self.buf_len -= front.len();
+					slices.push(front);
+				} else {
+					let front_take = read_len - taken;
+					slices.push(front.slice(..front_take));
+					self.buf.push_front(front.slice(front_take..));
+					self.buf_len -= front_take;
+					break;
+				}
+			}
+			Some(
+				slices
+					.iter()
+					.map(|x| &x[..])
+					.collect::<Vec<_>>()
+					.concat()
+					.into(),
+			)
+		} else {
+			None
+		}
+	}
+}
+
+pub enum ReadExactError {
+	UnexpectedEos,
+	Stream(u8),
+}
+
+#[pin_project::pin_project]
+pub struct ByteStreamReadExact<'a> {
+	#[pin]
+	reader: &'a mut ByteStreamReader,
+	read_len: usize,
+	fail_on_eos: bool,
+}
+
+impl<'a> Future for ByteStreamReadExact<'a> {
+	type Output = Result<Bytes, ReadExactError>;
+
+	fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<Bytes, ReadExactError>> {
+		let mut this = self.project();
+
+		loop {
+			if let Some(bytes) = this.reader.try_get(*this.read_len) {
+				return Poll::Ready(Ok(bytes));
+			}
+			if let Some(err) = this.reader.err {
+				return Poll::Ready(Err(ReadExactError::Stream(err)));
+			}
+			if this.reader.eos {
+				if *this.fail_on_eos {
+					return Poll::Ready(Err(ReadExactError::UnexpectedEos));
+				} else {
+					let bytes = Bytes::from(
+						this.reader
+							.buf
+							.iter()
+							.map(|x| &x[..])
+							.collect::<Vec<_>>()
+							.concat(),
+					);
+					this.reader.buf.clear();
+					this.reader.buf_len = 0;
+					return Poll::Ready(Ok(bytes));
+				}
+			}
+
+			match futures::ready!(this.reader.stream.as_mut().poll_next(cx)) {
+				Some(Ok(slice)) => {
+					this.reader.buf_len += slice.len();
+					this.reader.buf.push_back(slice);
+				}
+				Some(Err(e)) => {
+					this.reader.err = Some(e);
+					this.reader.eos = true;
+				}
+				None => {
+					this.reader.eos = true;
+				}
+			}
+		}
+	}
+}

src/util.rs

@@ -1,12 +1,9 @@
 use std::net::SocketAddr;
 use std::net::ToSocketAddrs;
-use std::pin::Pin;
 
-use bytes::Bytes;
 use log::info;
 use serde::Serialize;
 
-use futures::Stream;
 use tokio::sync::watch;
 
 /// A node's identifier, which is also its public cryptographic key
@@ -16,18 +13,6 @@ pub type NodeKey = sodiumoxide::crypto::sign::ed25519::SecretKey;
 /// A network key
 pub type NetworkKey = sodiumoxide::crypto::auth::Key;
 
-/// A stream of associated data.
-///
-/// The Stream can continue after receiving an error.
-/// When sent through Netapp, the Vec may be split in smaller chunk in such a way
-/// consecutive Vec may get merged, but Vec and error code may not be reordered
-///
-/// Error code 255 means the stream was cut before its end. Other codes have no predefined
-/// meaning, it's up to your application to define their semantic.
-pub type ByteStream = Pin<Box<dyn Stream<Item = Packet> + Send + Sync>>;
-
-pub type Packet = Result<Bytes, u8>;
-
 /// Utility function: encodes any serializable value in MessagePack binary format
 /// using the RMP library.
 ///