start supporting sending error on stream

src/proto.rs

@@ -78,7 +78,7 @@ enum DataReader {
 	Streaming {
 		#[pin]
 		reader: AssociatedStream,
-		packet: Vec<u8>,
+		packet: Result<Vec<u8>, u8>,
 		pos: usize,
 		buf: Vec<u8>,
 		eos: bool,
@@ -91,7 +91,7 @@ impl From<Data> for DataReader {
 			Data::Full(data) => DataReader::Full { data, pos: 0 },
 			Data::Streaming(reader) => DataReader::Streaming {
 				reader,
-				packet: Vec::new(),
+				packet: Ok(Vec::new()),
 				pos: 0,
 				buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
 				eos: false,
@@ -100,11 +100,18 @@ impl From<Data> for DataReader {
 	}
 }
 
-struct DataReaderItem {
+enum DataFrame {
+	Data {
 		/// a fixed size buffer containing some data, possibly padded with 0s
 		data: [u8; MAX_CHUNK_LENGTH as usize],
-	/// actuall lenght of data
+		/// actual lenght of data
 		len: usize,
+	},
+	Error(u8),
+}
+
+struct DataReaderItem {
+	data: DataFrame,
 	/// whethere there may be more data comming from this stream. Can be used for some
 	/// optimization. It's an error to set it to false if there is more data, but it is correct
 	/// (albeit sub-optimal) to set it to true if there is nothing coming after
@@ -114,11 +121,34 @@ struct DataReaderItem {
 impl DataReaderItem {
 	fn empty_last() -> Self {
 		DataReaderItem {
+			data: DataFrame::Data {
 				data: [0; MAX_CHUNK_LENGTH as usize],
 				len: 0,
+			},
 			may_have_more: false,
 		}
 	}
+
+	fn header(&self) -> [u8; 2] {
+		let continuation = if self.may_have_more {
+			CHUNK_HAS_CONTINUATION
+		} else {
+			0
+		};
+		let len = match self.data {
+			DataFrame::Data { len, .. } => len as u16,
+			DataFrame::Error(e) => e as u16 | ERROR_MARKER,
+		};
+
+		ChunkLength::to_be_bytes(len | continuation)
+	}
+
+	fn data(&self) -> &[u8] {
+		match self.data {
+			DataFrame::Data { ref data, len } => &data[..len],
+			DataFrame::Error(_) => &[],
+		}
+	}
 }
 
 impl Stream for DataReader {
@@ -137,15 +167,14 @@ impl Stream for DataReader {
 					body[..len].copy_from_slice(&data[*pos..end]);
 					*pos = end;
 					Poll::Ready(Some(DataReaderItem {
-						data: body,
+						data: DataFrame::Data { data: body, len },
-						len,
 						may_have_more: end < data.len(),
 					}))
 				}
 			}
 			DataReaderProj::Streaming {
 				mut reader,
-				packet,
+				packet: res_packet,
 				pos,
 				buf,
 				eos,
@@ -156,6 +185,17 @@ impl Stream for DataReader {
 					return Poll::Ready(None);
 				}
 				loop {
+					let packet = match res_packet {
+						Ok(v) => v,
+						Err(e) => {
+							let e = *e;
+							*res_packet = Ok(Vec::new());
+							return Poll::Ready(Some(DataReaderItem {
+								data: DataFrame::Error(e),
+								may_have_more: true,
+							}));
+						}
+					};
 					let packet_left = packet.len() - *pos;
 					let buf_left = MAX_CHUNK_LENGTH as usize - buf.len();
 					let to_read = std::cmp::min(buf_left, packet_left);
@@ -168,8 +208,13 @@ impl Stream for DataReader {
 
 					// we don't have a full buf, packet is empty; try receive more
 					if let Some(p) = futures::ready!(reader.as_mut().poll_next(cx)) {
-						*packet = p;
+						*res_packet = p;
 						*pos = 0;
+						// if buf is empty, we will loop and return the error directly. If buf
+						// isn't empty, send it before by breaking.
+						if res_packet.is_err() && !buf.is_empty() {
+							break;
+						}
 					} else {
 						*eos = true;
 						break;
@@ -181,8 +226,7 @@ impl Stream for DataReader {
 				body[..len].copy_from_slice(buf);
 				buf.clear();
 				Poll::Ready(Some(DataReaderItem {
-					data: body,
+					data: DataFrame::Data { data: body, len },
-					len,
 					may_have_more: !*eos,
 				}))
 			}
@@ -324,16 +368,8 @@ pub(crate) trait SendLoop: Sync {
 					let header_id = RequestID::to_be_bytes(id);
 					write.write_all(&header_id[..]).await?;
 
-					let body = &data.data[..data.len];
+					write.write_all(&data.header()).await?;
-
+					write.write_all(data.data()).await?;
-					let size_header = if data.may_have_more {
-						ChunkLength::to_be_bytes(data.len as u16 | CHUNK_HAS_CONTINUATION)
-					} else {
-						ChunkLength::to_be_bytes(data.len as u16)
-					};
-
-					write.write_all(&size_header[..]).await?;
-					write.write_all(body).await?;
 					write.flush().await?;
 				}
 			}
@@ -413,7 +449,13 @@ pub(crate) trait RecvLoop: Sync + 'static {
 			trace!("recv_loop: got header size: {:04x}", size);
 
 			let has_cont = (size & CHUNK_HAS_CONTINUATION) != 0;
-			let size = size & !CHUNK_HAS_CONTINUATION;
+			let is_error = (size & ERROR_MARKER) != 0;
+			let size = if !is_error {
+				size & !CHUNK_HAS_CONTINUATION
+			} else {
+				0
+			};
+			// TODO propagate errors
 
 			let mut next_slice = vec![0; size as usize];
 			read.read_exact(&mut next_slice[..]).await?;
@@ -430,7 +472,8 @@ pub(crate) trait RecvLoop: Sync + 'static {
 					let mut channel_pair = streams.remove(&(id | 1)).unwrap_or_default();
 
 					if let Some(receiver) = channel_pair.take_receiver() {
-						self.recv_handler(id, msg_bytes, Box::pin(receiver));
+						use futures::StreamExt;
+						self.recv_handler(id, msg_bytes, Box::pin(receiver.map(|v| Ok(v))));
 					} else {
 						warn!("Couldn't take receiver part of stream")
 					}

src/util.rs

@@ -27,7 +27,7 @@ pub type NetworkKey = sodiumoxide::crypto::auth::Key;
 ///
 /// The error code have no predefined meaning, it's up to you application to define their
 /// semantic.
-pub type AssociatedStream = Pin<Box<dyn Stream<Item = Vec<u8>> + Send>>;
+pub type AssociatedStream = Pin<Box<dyn Stream<Item = Result<Vec<u8>, u8>> + Send>>;
 
 /// Utility function: encodes any serializable value in MessagePack binary format
 /// using the RMP library.