Cleanup / temp buffers for various things

peer/control/ping.go

@@ -33,15 +33,18 @@ type Ping struct {
 	Dst    netip.AddrPort
 }
 
-// Marshal encodes p into a fixed-size 51-byte array.
-func (p Ping) Marshal() [Size]byte {
-	var buf [Size]byte
+// Marshal encodes p into buf (which must be at least Size bytes) and returns
+// buf[:Size]. Taking the buffer lets callers reuse one across sends; every
+// field is written unconditionally so a reused buffer needs no pre-zeroing.
+func (p Ping) Marshal(buf []byte) []byte {
 	buf[0] = version
 	binary.BigEndian.PutUint64(buf[1:9], uint64(p.PingTS))
 	if p.SrcV4.IsValid() {
 		a4 := p.SrcV4.Addr().As4()
 		copy(buf[9:13], a4[:])
 		binary.BigEndian.PutUint16(buf[13:15], p.SrcV4.Port())
+	} else {
+		clear(buf[9:15])
 	}
 	a16 := p.SrcV6.Addr().As16()
 	copy(buf[15:31], a16[:])
@@ -49,7 +52,7 @@ func (p Ping) Marshal() [Size]byte {
 	a16 = p.Dst.Addr().As16()
 	copy(buf[33:49], a16[:])
 	binary.BigEndian.PutUint16(buf[49:51], p.Dst.Port())
-	return buf
+	return buf[:Size]
 }
 
 // Unmarshal decodes a Ping from a fixed-size 51-byte array.