fix: skip empty DATA frames when receiving body data

h3/src/connection.rs

@@ -855,7 +855,8 @@ where
         &mut self,
         cx: &mut Context<'_>,
     ) -> Poll<Result<Option<impl Buf>, StreamError>> {
-        if !self.stream.has_data() {
+        // Empty DATA frames do not end the body.
+        while !self.stream.has_data() {
             match ready!(self.stream.poll_next(cx)) {
                 Err(frame_stream_error) => {
                     return Poll::Ready(Err(

h3/src/tests/request.rs

@@ -1091,6 +1091,27 @@ async fn request_valid_header_multiple_data_trailer() {
     .await;
 }
 
+#[tokio::test]
+async fn request_valid_empty_data_frames() {
+    for with_trailers in [false, true] {
+        request_sequence_ok(|mut buf| {
+            request_encode(
+                &mut buf,
+                Request::post("http://localhost/salut").body(()).unwrap(),
+            );
+            for chunk in ["", "", "hello", "", "", " world", "", ""] {
+                Frame::Data(Bytes::from(chunk)).encode_with_payload(&mut buf);
+            }
+            if with_trailers {
+                let mut trailers = HeaderMap::new();
+                trailers.insert("trailer", "value".parse().unwrap());
+                trailers_encode(buf, trailers);
+            }
+        })
+        .await;
+    }
+}
+
 #[tokio::test]
 async fn request_valid_header_trailer() {
     request_sequence_ok(|mut buf| {