Yield protocol violation for packets without frames

quinn-proto/src/connection/mod.rs

@@ -2192,7 +2192,7 @@ impl Connection {
                 return Ok(());
             }
             State::Closed(_) => {
-                for result in frame::Iter::new(packet.payload.freeze()) {
+                for result in frame::Iter::new(packet.payload.freeze())? {
                     let frame = match result {
                         Ok(frame) => frame,
                         Err(err) => {
@@ -2441,7 +2441,7 @@ impl Connection {
         debug_assert_ne!(packet.header.space(), SpaceId::Data);
         let payload_len = packet.payload.len();
         let mut ack_eliciting = false;
-        for result in frame::Iter::new(packet.payload.freeze()) {
+        for result in frame::Iter::new(packet.payload.freeze())? {
             let frame = result?;
             let span = match frame {
                 Frame::Padding => continue,
@@ -2499,7 +2499,7 @@ impl Connection {
         let mut close = None;
         let payload_len = payload.len();
         let mut ack_eliciting = false;
-        for result in frame::Iter::new(payload) {
+        for result in frame::Iter::new(payload)? {
             let frame = result?;
             let span = match frame {
                 Frame::Padding => continue,

quinn-proto/src/frame.rs

@@ -550,11 +550,20 @@ impl From<UnexpectedEnd> for IterErr {
 }
 
 impl Iter {
-    pub(crate) fn new(payload: Bytes) -> Self {
-        Self {
+    pub(crate) fn new(payload: Bytes) -> Result<Self, TransportError> {
+        if payload.is_empty() {
+            // "An endpoint MUST treat receipt of a packet containing no frames as a
+            // connection error of type PROTOCOL_VIOLATION."
+            // https://www.rfc-editor.org/rfc/rfc9000.html#name-frames-and-frame-types
+            return Err(TransportError::PROTOCOL_VIOLATION(
+                "packet payload is empty",
+            ));
+        }
+
+        Ok(Self {
             bytes: io::Cursor::new(payload),
             last_ty: None,
-        }
+        })
     }
 
     fn take_len(&mut self) -> Result<Bytes, UnexpectedEnd> {
@@ -923,6 +932,7 @@ mod test {
 
     fn frames(buf: Vec<u8>) -> Vec<Frame> {
         Iter::new(Bytes::from(buf))
+            .unwrap()
             .collect::<Result<Vec<_>, _>>()
             .unwrap()
     }

quinn-proto/src/tests/mod.rs

@@ -2257,6 +2257,7 @@ fn single_ack_eliciting_packet_triggers_ack_after_delay() {
     // The ACK delay is properly calculated
     assert_eq!(pair.client.captured_packets.len(), 1);
     let mut frames = frame::Iter::new(pair.client.captured_packets.remove(0).into())
+        .unwrap()
         .collect::<Result<Vec<_>, _>>()
         .unwrap();
     assert_eq!(frames.len(), 1);