From f47497bf1944ca41c4edf3e1eea20994032c8d92 Mon Sep 17 00:00:00 2001
From: Will Hawkins <hawkinsw@obs.cr>
Date: Mon, 14 Oct 2024 19:14:28 -0400
Subject: [PATCH] support en/decoding the accurate ECN transport param

Properly encode/decode the accurate ECN transport param
(I-D.seemann-quic-accurate-ack-ecn,
https://datatracker.ietf.org/doc/html/draft-seemann-quic-accurate-ack-ecn-01).
---
 quiche/src/lib.rs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/quiche/src/lib.rs b/quiche/src/lib.rs
index bf9c27824e..466c79a72b 100644
--- a/quiche/src/lib.rs
+++ b/quiche/src/lib.rs
@@ -8023,6 +8023,8 @@ pub struct TransportParams {
     pub retry_source_connection_id: Option<ConnectionId<'static>>,
     /// DATAGRAM frame extension parameter, if any.
     pub max_datagram_frame_size: Option<u64>,
+    /// Whether accurate ECN support is enabled.
+    pub accurate_ecn_enabled: bool,
     // pub preferred_address: ...,
 }
 
@@ -8046,6 +8048,7 @@ impl Default for TransportParams {
             initial_source_connection_id: None,
             retry_source_connection_id: None,
             max_datagram_frame_size: None,
+            accurate_ecn_enabled: false,
         }
     }
 }
@@ -8196,6 +8199,10 @@ impl TransportParams {
                     tp.max_datagram_frame_size = Some(val.get_varint()?);
                 },
 
+                0x2051a5fa8648af => {
+                    tp.accurate_ecn_enabled = true;
+                },
+
                 // Ignore unknown parameters.
                 _ => (),
             }
@@ -8358,6 +8365,10 @@ impl TransportParams {
             b.put_varint(max_datagram_frame_size)?;
         }
 
+        if tp.accurate_ecn_enabled {
+            TransportParams::encode_param(&mut b, 0x2051a5fa8648af, 0)?;
+        }
+
         let out_len = b.off();
 
         Ok(&mut out[..out_len])
@@ -8952,12 +8963,13 @@ mod tests {
             initial_source_connection_id: Some(b"woot woot".to_vec().into()),
             retry_source_connection_id: Some(b"retry".to_vec().into()),
             max_datagram_frame_size: Some(32),
+            accurate_ecn_enabled: true,
         };
 
         let mut raw_params = [42; 256];
         let raw_params =
             TransportParams::encode(&tp, true, &mut raw_params).unwrap();
-        assert_eq!(raw_params.len(), 94);
+        assert_eq!(raw_params.len(), 103);
 
         let new_tp = TransportParams::decode(raw_params, false).unwrap();
 
@@ -8982,12 +8994,13 @@ mod tests {
             initial_source_connection_id: Some(b"woot woot".to_vec().into()),
             retry_source_connection_id: None,
             max_datagram_frame_size: Some(32),
+            accurate_ecn_enabled: true,
         };
 
         let mut raw_params = [42; 256];
         let raw_params =
             TransportParams::encode(&tp, false, &mut raw_params).unwrap();
-        assert_eq!(raw_params.len(), 69);
+        assert_eq!(raw_params.len(), 78);
 
         let new_tp = TransportParams::decode(raw_params, true).unwrap();