some fixes for PathId as a transport param

Author: divagant-martian

quinn-proto/src/config/transport.rs

@@ -1,8 +1,8 @@
 use std::{fmt, sync::Arc};
 
 use crate::{
-    address_discovery, congestion, Duration, VarInt, VarIntBoundsExceeded, INITIAL_MTU,
-    MAX_UDP_PAYLOAD,
+    address_discovery, congestion, connection::PathId, Duration, VarInt, VarIntBoundsExceeded,
+    INITIAL_MTU, MAX_UDP_PAYLOAD,
 };
 
 /// Parameters governing the core QUIC state machine
@@ -48,7 +48,7 @@ pub struct TransportConfig {
     pub(crate) enable_segmentation_offload: bool,
 
     pub(crate) address_discovery_role: address_discovery::Role,
-    pub(crate) initial_max_path_id: Option<VarInt>,
+    pub(crate) initial_max_path_id: Option<PathId>,
 }
 
 impl TransportConfig {
@@ -344,7 +344,7 @@ impl TransportConfig {
 
     /// DOCS :D
     // TODO(@divma): decent docs, talk about multipath, reference draft.
-    pub fn initial_max_path_id(&mut self, value: Option<VarInt>) -> &mut Self {
+    pub fn initial_max_path_id(&mut self, value: Option<PathId>) -> &mut Self {
         self.initial_max_path_id = value;
         self
     }

quinn-proto/src/connection/paths.rs

@@ -31,6 +31,20 @@ impl coding::Codec for PathId {
     }
 }
 
+impl PathId {
+    pub const MAX: Self = PathId(u32::MAX);
+
+    pub(crate) fn size(&self) -> usize {
+        VarInt(self.0 as u64).size()
+    }
+}
+
+impl std::fmt::Display for PathId {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
 /// Description of a particular network path
 pub(super) struct PathData {
     pub(super) remote: SocketAddr,

quinn-proto/src/transport_parameters.rs

@@ -21,6 +21,7 @@ use crate::{
     cid_queue::CidQueue,
     coding::{BufExt, BufMutExt, UnexpectedEnd},
     config::{EndpointConfig, ServerConfig, TransportConfig},
+    connection::PathId,
     shared::ConnectionId,
     ResetToken, Side, TransportError, VarInt, LOC_CID_COUNT, MAX_CID_SIZE, MAX_STREAM_COUNT,
     RESET_TOKEN_SIZE, TIMER_GRANULARITY,
@@ -117,7 +118,7 @@ macro_rules! make_struct {
             pub(crate) address_discovery_role: address_discovery::Role,
 
             // Multipath extension
-            pub(crate) initial_max_path_id: Option<VarInt>,
+            pub(crate) initial_max_path_id: Option<PathId>,
         }
 
         // We deliberately don't implement the `Default` trait, since that would be public, and
@@ -528,7 +529,7 @@ impl TransportParameters {
                         return Err(Error::Malformed);
                     }
 
-                    let value: VarInt = r.get()?;
+                    let value: PathId = r.get()?;
                     if len != value.size() {
                         return Err(Error::Malformed);
                     }
@@ -708,7 +709,7 @@ pub(crate) enum TransportParameterId {
 
 impl TransportParameterId {
     /// Array with all supported transport parameter IDs
-    const SUPPORTED: [Self; 22] = [
+    const SUPPORTED: [Self; 23] = [
         Self::MaxIdleTimeout,
         Self::MaxUdpPayloadSize,
         Self::InitialMaxData,
@@ -731,6 +732,7 @@ impl TransportParameterId {
         Self::GreaseQuicBit,
         Self::MinAckDelayDraft07,
         Self::ObservedAddr,
+        Self::InitialMaxPathId,
     ];
 }
 
@@ -810,7 +812,7 @@ mod test {
             grease_quic_bit: true,
             min_ack_delay: Some(2_000u32.into()),
             address_discovery_role: address_discovery::Role::SendOnly,
-            initial_max_path_id: Some(VarInt::MAX),
+            initial_max_path_id: Some(PathId::MAX),
             ..TransportParameters::default()
         };
         params.write(&mut buf);