Encode/decode PathId as VarInt

Author: flub

quinn-proto/src/connection/paths.rs

@@ -9,7 +9,7 @@ use super::{
 };
 use crate::{
     coding, congestion, frame::ObservedAddr, packet::SpaceId, Duration, Instant, TransportConfig,
-    TIMER_GRANULARITY,
+    VarInt, TIMER_GRANULARITY,
 };
 
 /// Id representing different paths when using multipath extension
@@ -19,13 +19,15 @@ pub struct PathId(pub(crate) u32);
 
 impl coding::Codec for PathId {
     fn decode<B: bytes::Buf>(r: &mut B) -> coding::Result<Self> {
-        // TODO(@divma): unclear if the encoding is similar to the varint or plain u32, in any case
-        // the change needs to be done just here
-        Ok(Self(u32::decode(r)?))
+        let v = VarInt::decode(r)?;
+        // TODO(@flub): Mapping this error is not nice, maybe the error type should have 2
+        // variants.
+        let v = u32::try_from(v.0).map_err(|_| coding::UnexpectedEnd)?;
+        Ok(Self(v as u32))
     }
 
     fn encode<B: bytes::BufMut>(&self, w: &mut B) {
-        self.0.encode(w)
+        VarInt(self.0 as u64).encode(w)
     }
 }