reconsider to load request/response body data. believe quinn to properly handle buffering body

src/proxy/proxy_h3.rs

@@ -1,9 +1,9 @@
 use super::Proxy;
 use crate::{backend::ServerNameLC, constants::*, error::*, log::*};
-use bytes::{Buf, BufMut, Bytes, BytesMut};
+use bytes::{Buf, Bytes};
 use h3::{quic::BidiStream, server::RequestStream};
 use hyper::{client::connect::Connect, Body, Request, Response};
-use std::{io::Read, net::SocketAddr};
+use std::net::SocketAddr;
 use tokio::time::{timeout, Duration};
 
 impl<T> Proxy<T>
@@ -94,36 +94,43 @@ where
   async fn handle_stream_h3<S>(
     self,
     req: Request<()>,
-    mut stream: RequestStream<S, Bytes>,
+    stream: RequestStream<S, Bytes>,
     client_addr: SocketAddr,
     tls_server_name: ServerNameLC,
   ) -> Result<()>
   where
-    S: BidiStream<Bytes>,
+    S: BidiStream<Bytes> + Send + 'static,
+    <S as BidiStream<Bytes>>::RecvStream: Send,
   {
     let (req_parts, _) = req.into_parts();
-    // let (mut send_stream, mut recv_stream) = stream.split(); // TODO: split stream and async body handling
-
-    // TODO: h3 -> h2/http1.1等のプロトコル変換のため、一旦全部バッファリングしないと無理そう。H3->H3ならBytesを直に流し込めるのだが。
-    let mut body_buf = BytesMut::new();
-    while let Some(chunk) = stream.recv_data().await? {
-      debug!("HTTP/3 request body");
-      if body_buf.len() + chunk.remaining() > H3_REQUEST_MAX_BODY_SIZE {
-        error!("Exceeds max request body size for HTTP/3");
-        return Err(anyhow!("Exceeds max request body size for HTTP/3"));
-      }
-      body_buf.put(chunk);
-    }
-    // trailers
-    let trailers = stream.recv_trailers().await?;
+    // split stream and async body handling
+    let (mut send_stream, mut recv_stream) = stream.split();
 
     // generate streamed body with trailers using channel
     let (body_sender, req_body) = Body::channel();
+
+    // Buffering and sending body through channel for protocol conversion like h3 -> h2/http1.1
+    // The underling buffering, i.e., buffer given by the API recv_data.await?, is handled by quinn.
     self.globals.runtime_handle.spawn(async move {
       let mut sender = body_sender;
-      sender.send_data(body_buf.freeze()).await?;
+      let mut size = 0usize;
+      while let Some(mut body) = recv_stream.recv_data().await? {
+        debug!("HTTP/3 incoming request body");
+        size += body.remaining();
+        if size > H3_REQUEST_MAX_BODY_SIZE {
+          error!("Exceeds max request body size for HTTP/3");
+          return Err(anyhow!("Exceeds max request body size for HTTP/3"));
+        }
+        // create stream body to save memory, shallow copy (increment of ref-count) to Bytes using copy_to_bytes
+        sender
+          .send_data(body.copy_to_bytes(body.remaining()))
+          .await?;
+      }
+
+      // trailers: use inner for work around. (directly get trailer)
+      let trailers = recv_stream.as_mut().recv_trailers().await?;
       if trailers.is_some() {
-        debug!("HTTP/3 request with trailers");
+        debug!("HTTP/3 incoming request trailers");
         sender.send_trailers(trailers.unwrap()).await?;
       }
       Ok(()) as Result<()>
@@ -145,27 +152,23 @@ where
     let (new_res_parts, new_body) = res.into_parts();
     let new_res = Response::from_parts(new_res_parts, ());
 
-    match stream.send_response(new_res).await {
+    match send_stream.send_response(new_res).await {
       Ok(_) => {
         debug!("HTTP/3 response to connection successful");
-        let body_data = hyper::body::aggregate(new_body).await?; // aggregate body without copying
-        let mut reader = body_data.reader();
-        let mut buf = [0u8; H3_RESPONSE_BUF_SIZE];
-        loop {
-          let num = reader.read(&mut buf)?;
-          if num == 0 {
-            break;
-          }
-          stream
-            .send_data(Bytes::copy_from_slice(&buf[..num]))
-            .await?;
-        }
+        // aggregate body without copying
+        let mut body_data = hyper::body::aggregate(new_body).await?;
+
+        // create stream body to save memory, shallow copy (increment of ref-count) to Bytes using copy_to_bytes
+        send_stream
+          .send_data(body_data.copy_to_bytes(body_data.remaining()))
+          .await?;
+
         // TODO: needs handling trailer? should be included in body from handler.
       }
       Err(err) => {
         error!("Unable to send response to connection peer: {:?}", err);
       }
     }
-    Ok(stream.finish().await?)
+    Ok(send_stream.finish().await?)
   }
 }