Reduce allocation in udp muxed conn addr decode (#686)

udp_mux_test.go

@@ -173,11 +173,25 @@ func BenchmarkAddressEncoding(b *testing.B) {
 	}
 	buf := make([]byte, 64)
 
-	for i := 0; i < b.N; i++ {
-		if _, err := encodeUDPAddr(addr, buf); err != nil {
-			require.NoError(b, err)
+	b.Run("encode", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			if _, err := encodeUDPAddr(addr, buf); err != nil {
+				require.NoError(b, err)
+			}
 		}
-	}
+	})
+
+	b.Run("decode", func(b *testing.B) {
+		n, _ := encodeUDPAddr(addr, buf)
+		var addr *net.UDPAddr
+		var err error
+		for i := 0; i < b.N; i++ {
+			if addr, err = decodeUDPAddr(buf[:n]); err != nil {
+				require.NoError(b, err)
+			}
+		}
+		_ = addr
+	})
 }
 
 func testMuxConnection(t *testing.T, udpMux *UDPMuxDefault, ufrag string, network string) {

udp_muxed_conn.go

@@ -7,11 +7,8 @@ import (
 	"encoding/binary"
 	"io"
 	"net"
-	"net/netip"
-	"reflect"
 	"sync"
 	"time"
-	"unsafe"
 
 	"github.com/pion/logging"
 	"github.com/pion/transport/v3/packetio"
@@ -214,51 +211,46 @@ func (c *udpMuxedConn) writePacket(data []byte, addr *net.UDPAddr) error {
 }
 
 func encodeUDPAddr(addr *net.UDPAddr, buf []byte) (int, error) {
-	if len(addr.IP) != 0 && len(addr.IP) != net.IPv4len && len(addr.IP) != net.IPv6len {
-		return 0, errInvalidAddress
-	}
-
-	var n int
-	if ip4 := addr.IP.To4(); len(ip4) == net.IPv4len {
-		d := (*reflect.SliceHeader)(unsafe.Pointer(&ip4))                                // nolint:gosec
-		n = len(netip.AddrFrom4(*(*[4]byte)(unsafe.Pointer(d.Data))).AppendTo(buf[2:2])) // nolint:gosec
-	} else if len(addr.IP) != 0 {
-		d := (*reflect.SliceHeader)(unsafe.Pointer(&addr.IP))                              // nolint:gosec
-		n = len(netip.AddrFrom16(*(*[16]byte)(unsafe.Pointer(d.Data))).AppendTo(buf[2:2])) // nolint:gosec
-	}
-
-	total := 2 + n + 2 + len(addr.Zone)
-	if total > len(buf) {
+	total := 1 + len(addr.IP) + 2 + len(addr.Zone)
+	if len(buf) < total {
 		return 0, io.ErrShortBuffer
 	}
 
-	binary.LittleEndian.PutUint16(buf, uint16(n))
-	offset := 2 + n
+	buf[0] = uint8(len(addr.IP))
+	offset := 1
+
+	copy(buf[offset:], addr.IP)
+	offset += len(addr.IP)
+
 	binary.LittleEndian.PutUint16(buf[offset:], uint16(addr.Port))
 	offset += 2
+
 	copy(buf[offset:], addr.Zone)
 	return total, nil
 }
 
 func decodeUDPAddr(buf []byte) (*net.UDPAddr, error) {
-	addr := net.UDPAddr{}
+	addr := &net.UDPAddr{}
 
-	offset := 0
-	ipLen := int(binary.LittleEndian.Uint16(buf[:2]))
-	offset += 2
 	// Basic bounds checking
-	if ipLen+offset > len(buf) {
+	if len(buf) == 0 || len(buf) < int(buf[0])+3 {
 		return nil, io.ErrShortBuffer
 	}
-	if err := addr.IP.UnmarshalText(buf[offset : offset+ipLen]); err != nil {
-		return nil, err
-	}
-	offset += ipLen
-	addr.Port = int(binary.LittleEndian.Uint16(buf[offset : offset+2]))
-	offset += 2
-	zone := make([]byte, len(buf[offset:]))
-	copy(zone, buf[offset:])
-	addr.Zone = string(zone)
 
-	return &addr, nil
+	ipLen := int(buf[0])
+	offset := 1
+
+	if ipLen == 0 {
+		addr.IP = nil
+	} else {
+		addr.IP = append(addr.IP[:0], buf[offset:offset+ipLen]...)
+		offset += ipLen
+	}
+
+	addr.Port = int(binary.LittleEndian.Uint16(buf[offset:]))
+	offset += 2
+
+	addr.Zone = string(buf[offset:])
+
+	return addr, nil
 }