Cleanup / temp buffers for various things

peer/app.go

@@ -23,6 +23,10 @@ const (
 	TimeoutInterval = 30 * time.Second
 )
 
+// scratchSize is large enough for the biggest buffer either the ping or the
+// multicast path serializes through the shared App scratch.
+const scratchSize = max(control.Size, multicast.SignedPacketSize)
+
 type PingEvent struct {
 	srcVPNIP netip.Addr
 	ping     control.Ping
@@ -53,8 +57,9 @@ type App struct {
 	selfV4 netip.AddrPort
 	selfV6 netip.AddrPort
 
-	// Reusable scratch for multicast signature verification (event loop only).
-	mcVerifyBuf []byte
+	// Reusable serialization scratch for outgoing pings and multicast signature
+	// verification. Only touched from the Run goroutine.
+	scratch []byte
 
 	// Event channels fed by background goroutines
 	hubAddCh    <-chan m.Peer