use bytes::Bytes; use serde::{Deserialize, Serialize}; use futures::stream::{Stream, StreamExt}; use crate::error::*; use crate::util::*; /// Priority of a request (click to read more about priorities). /// /// This priority value is used to priorize messages /// in the send queue of the client, and their responses in the send queue of the /// server. Lower values mean higher priority. /// /// This mechanism is usefull for messages bigger than the maximum chunk size /// (set at `0x4000` bytes), such as large file transfers. /// In such case, all of the messages in the send queue with the highest priority /// will take turns to send individual chunks, in a round-robin fashion. /// Once all highest priority messages are sent successfully, the messages with /// the next highest priority will begin being sent in the same way. /// /// The same priority value is given to a request and to its associated response. pub type RequestPriority = u8; /// Priority class: high pub const PRIO_HIGH: RequestPriority = 0x20; /// Priority class: normal pub const PRIO_NORMAL: RequestPriority = 0x40; /// Priority class: background pub const PRIO_BACKGROUND: RequestPriority = 0x80; /// Priority: primary among given class pub const PRIO_PRIMARY: RequestPriority = 0x00; /// Priority: secondary among given class (ex: `PRIO_HIGH | PRIO_SECONDARY`) pub const PRIO_SECONDARY: RequestPriority = 0x01; // ---- /// This trait should be implemented by all messages your application /// wants to handle pub trait Message: SerializeMessage + Send + Sync { type Response: SerializeMessage + Send + Sync; } /// A trait for de/serializing messages, with possible associated stream. /// This is default-implemented by anything that can already be serialized /// and deserialized. Adapters are provided that implement this for /// adding a body, either from a fixed Bytes buffer (which allows the thing /// to be Clone), or from a streaming byte stream. pub trait SerializeMessage: Sized { type SerializableSelf: Serialize + for<'de> Deserialize<'de> + Send; fn into_parts(self) -> (Self::SerializableSelf, Option); fn from_parts(ser_self: Self::SerializableSelf, stream: ByteStream) -> Self; } // ---- impl SerializeMessage for T where T: Serialize + for<'de> Deserialize<'de> + Send, { type SerializableSelf = Self; fn into_parts(self) -> (Self::SerializableSelf, Option) { (self, None) } fn from_parts(ser_self: Self::SerializableSelf, _stream: ByteStream) -> Self { // TODO verify no stream ser_self } } // ---- /// An adapter that adds a body from a fixed Bytes buffer to a serializable message, /// implementing the SerializeMessage trait. This allows for the SerializeMessage object /// to be cloned, which is usefull for requests that must be sent to multiple servers. /// Note that cloning the body is cheap thanks to Bytes; make sure that your serializable /// part is also easily clonable (e.g. by wrapping it in an Arc). /// Note that this CANNOT be used for a response type, as it cannot be reconstructed /// from a remote stream. #[derive(Clone)] pub struct WithFixedBody Deserialize<'de> + Clone + Send + 'static>( pub T, pub Bytes, ); impl SerializeMessage for WithFixedBody where T: Serialize + for<'de> Deserialize<'de> + Clone + Send + 'static, { type SerializableSelf = T; fn into_parts(self) -> (Self::SerializableSelf, Option) { let body = self.1; ( self.0, Some(Box::pin(futures::stream::once(async move { Ok(body) }))), ) } fn from_parts(_ser_self: Self::SerializableSelf, _stream: ByteStream) -> Self { panic!("Cannot use a WithFixedBody as a response type"); } } /// An adapter that adds a body from a ByteStream. This is usefull for receiving /// responses to requests that contain attached byte streams. This type is /// not clonable. pub struct WithStreamingBody Deserialize<'de> + Send>( pub T, pub ByteStream, ); impl SerializeMessage for WithStreamingBody where T: Serialize + for<'de> Deserialize<'de> + Send, { type SerializableSelf = T; fn into_parts(self) -> (Self::SerializableSelf, Option) { (self.0, Some(self.1)) } fn from_parts(ser_self: Self::SerializableSelf, stream: ByteStream) -> Self { WithStreamingBody(ser_self, stream) } } // ---- ---- pub(crate) struct QueryMessage<'a> { pub(crate) prio: RequestPriority, pub(crate) path: &'a [u8], pub(crate) telemetry_id: Option>, 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; ..] impl<'a> QueryMessage<'a> { pub(crate) fn encode(self) -> Vec { let tel_len = match &self.telemetry_id { Some(t) => t.len(), None => 0, }; let mut ret = Vec::with_capacity(10 + self.path.len() + tel_len + self.body.len()); ret.push(self.prio); ret.push(self.path.len() as u8); ret.extend_from_slice(self.path); if let Some(t) = self.telemetry_id { ret.push(t.len() as u8); ret.extend(t); } else { ret.push(0u8); } ret.extend_from_slice(self.body); ret } pub(crate) fn decode(bytes: &'a [u8]) -> Result { if bytes.len() < 3 { return Err(Error::Message("Invalid protocol message".into())); } let path_length = bytes[1] as usize; if bytes.len() < 3 + path_length { return Err(Error::Message("Invalid protocol message".into())); } let telemetry_id_len = bytes[2 + path_length] as usize; 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 telemetry_id = if telemetry_id_len > 0 { Some(bytes[3 + path_length..3 + path_length + telemetry_id_len].to_vec()) } else { None }; let body = &bytes[3 + path_length + telemetry_id_len..]; Ok(Self { prio: bytes[0], path, telemetry_id, body, }) } } // ---- ---- pub(crate) struct Framing { direct: Vec, stream: Option, } impl Framing { pub fn new(direct: Vec, stream: Option) -> Self { assert!(direct.len() <= u32::MAX as usize); Framing { direct, stream } } 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 + Unpin + Send + 'static>( mut stream: S, ) -> Result { let mut packet = stream .next() .await .ok_or(Error::Framing)? .map_err(|_| Error::Framing)?; if packet.len() < 4 { return Err(Error::Framing); } let mut len = [0; 4]; len.copy_from_slice(&packet[..4]); let len = u32::from_be_bytes(len); packet = packet.slice(4..); let mut buffer = Vec::new(); let len = len as usize; loop { let max_cp = std::cmp::min(len - buffer.len(), packet.len()); buffer.extend_from_slice(&packet[..max_cp]); if buffer.len() == len { packet = packet.slice(max_cp..); break; } 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, ByteStream) { let Framing { direct, stream } = self; (direct, stream.unwrap_or(Box::pin(futures::stream::empty()))) } }