Freedom: Cache UDP resolve result

proxy/freedom/freedom.go

@@ -328,22 +328,12 @@ func NewPacketWriter(conn net.Conn, h *Handler, ctx context.Context, UDPOverride
 		counter = statConn.WriteCounter
 	}
 	if c, ok := iConn.(*internet.PacketConnWrapper); ok {
-		// If target is a domain, it will be resolved in dialer
-		// check this behavior and add it to map
-		outbounds := session.OutboundsFromContext(ctx)
-		targetAddr := outbounds[len(outbounds)-1].Target.Address
-		resolvedUDPAddr := make(map[string]net.Address)
-		if targetAddr.Family().IsDomain() {
-			RemoteAddress, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
-			resolvedUDPAddr[targetAddr.String()] = net.ParseAddress(RemoteAddress)
-		}
 		return &PacketWriter{
 			PacketConnWrapper: c,
 			Counter:           counter,
 			Handler:           h,
 			Context:           ctx,
 			UDPOverride:       UDPOverride,
-			resolvedUDPAddr:   resolvedUDPAddr,
 		}
 
 	}
@@ -361,7 +351,7 @@ type PacketWriter struct {
 	// But resolver will return a random one if the domain has many IPs
 	// Resulting in these packets being sent to many different IPs randomly
 	// So, cache and keep the resolve result
-	resolvedUDPAddr map[string]net.Address
+	resolvedUDPAddr map[string]*net.UDPAddr
 }
 
 func (w *PacketWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
@@ -380,18 +370,19 @@ func (w *PacketWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
 			if w.UDPOverride.Port != 0 {
 				b.UDP.Port = w.UDPOverride.Port
 			}
+			var destAddr *net.UDPAddr
+			if w.resolvedUDPAddr == nil {
 				if w.Handler.config.hasStrategy() && b.UDP.Address.Family().IsDomain() {
-				if ip := w.resolvedUDPAddr[b.UDP.Address.Domain()]; ip != nil {
-					b.UDP.Address = ip
-				} else {
 					ip := w.Handler.resolveIP(w.Context, b.UDP.Address.Domain(), nil)
 					if ip != nil {
 						b.UDP.Address = ip
-						w.resolvedUDPAddr[b.UDP.Address.Domain()] = ip
 					}
 				}
+				destAddr, _ = net.ResolveUDPAddr("udp", b.UDP.NetAddr())
+				w.resolvedUDPAddr[b.UDP.NetAddr()] = destAddr
+			} else {
+				destAddr = w.resolvedUDPAddr[b.UDP.NetAddr()]
 			}
-			destAddr, _ := net.ResolveUDPAddr("udp", b.UDP.NetAddr())
 			if destAddr == nil {
 				b.Release()
 				continue