quinn-rs#2057: Option to disable grease random transport parameter.

quinn-proto/src/config.rs

@@ -63,6 +63,8 @@ pub struct TransportConfig {
     pub(crate) congestion_controller_factory: Arc<dyn congestion::ControllerFactory + Send + Sync>,
 
     pub(crate) enable_segmentation_offload: bool,
+
+    pub(crate) enable_grease_random_transport_parameter: bool,
 }
 
 impl TransportConfig {
@@ -334,6 +336,18 @@ impl TransportConfig {
         self.enable_segmentation_offload = enabled;
         self
     }
+
+    /// Specify if grease random transport parameter need to be included into transport parameters 
+    /// during connection negotiation
+    ///
+    /// Default to `true`
+    ///
+    /// Will cause quinn to include single grease transport parameter
+    /// with ID in form of 37 * N + 21 with random payload.
+    pub fn enable_grease_random_transport_parameter(&mut self, enabled: bool) -> &mut Self {
+        self.enable_grease_random_transport_parameter = enabled;
+        self
+    }
 }
 
 impl Default for TransportConfig {
@@ -374,6 +388,8 @@ impl Default for TransportConfig {
             congestion_controller_factory: Arc::new(congestion::CubicConfig::default()),
 
             enable_segmentation_offload: true,
+
+            enable_grease_random_transport_parameter: true,
         }
     }
 }
@@ -405,6 +421,7 @@ impl fmt::Debug for TransportConfig {
                 deterministic_packet_numbers: _,
             congestion_controller_factory: _,
             enable_segmentation_offload,
+            enable_grease_random_transport_parameter,
         } = self;
         fmt.debug_struct("TransportConfig")
             .field("max_concurrent_bidi_streams", max_concurrent_bidi_streams)
@@ -432,6 +449,10 @@ impl fmt::Debug for TransportConfig {
             .field("datagram_send_buffer_size", datagram_send_buffer_size)
             .field("congestion_controller_factory", &"[ opaque ]")
             .field("enable_segmentation_offload", enable_segmentation_offload)
+            .field(
+                "enable_grease_random_transport_parameter",
+                enable_grease_random_transport_parameter,
+            )
             .finish()
     }
 }

quinn-proto/src/transport_parameters.rs

@@ -100,6 +100,9 @@ macro_rules! make_struct {
             pub(crate) stateless_reset_token: Option<ResetToken>,
             /// The server's preferred address for communication after handshake completion
             pub(crate) preferred_address: Option<PreferredAddress>,
+            /// Indicator if single grease transport parameter will be sent over wire in case of
+            /// client or any number of grease transport parameters received in case of server.
+            pub(crate) grease_parameter_present: bool,
         }
 
         // We deliberately don't implement the `Default` trait, since that would be public, and
@@ -121,6 +124,7 @@ macro_rules! make_struct {
                     retry_src_cid: None,
                     stateless_reset_token: None,
                     preferred_address: None,
+                    grease_parameter_present: false,
                 }
             }
         }
@@ -161,6 +165,7 @@ impl TransportParameters {
             min_ack_delay: Some(
                 VarInt::from_u64(u64::try_from(TIMER_GRANULARITY.as_micros()).unwrap()).unwrap(),
             ),
+            grease_parameter_present: config.enable_grease_random_transport_parameter,
             ..Self::default()
         }
     }
@@ -301,7 +306,9 @@ impl TransportParameters {
         }
         apply_params!(write_params);
 
-        write_random_grease_reserved_parameter(w, &mut rand::thread_rng());
+        if self.grease_parameter_present {
+            write_random_grease_reserved_parameter(w, &mut rand::thread_rng());
+        }
 
         if let Some(ref x) = self.stateless_reset_token {
             w.write_var(0x02);
@@ -422,7 +429,12 @@ impl TransportParameters {
                                     params.$name = value.into();
                                     got.$name = true;
                                 })*
-                                _ => r.advance(len as usize),
+                                id => {
+                                    if id % 31 == 27 {
+                                        params.grease_parameter_present = true;
+                                    }
+                                    r.advance(len as usize)
+                                },
                             }
                         }
                     }
@@ -564,9 +576,11 @@ mod test {
         for rng in &mut rngs {
             let mut buf = Vec::new();
             write_random_grease_reserved_parameter(&mut buf, rng);
+            let mut expected_params = TransportParameters::default();
+            expected_params.grease_parameter_present = true;
             assert_eq!(
                 TransportParameters::read(Side::Client, &mut buf.as_slice()).unwrap(),
-                TransportParameters::default(),
+                expected_params,
             );
         }
     }