Add init check

proxy/freedom/freedom.go

@@ -328,12 +328,22 @@ 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,
 		}
 
 	}
@@ -346,6 +356,12 @@ type PacketWriter struct {
 	*Handler
 	context.Context
 	UDPOverride net.Destination
+
+	// Dest of udp packets might be a domain, we will resolve them to IP
+	// 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
 }
 
 func (w *PacketWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
@@ -365,9 +381,14 @@ func (w *PacketWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
 				b.UDP.Port = w.UDPOverride.Port
 			}
 			if w.Handler.config.hasStrategy() && b.UDP.Address.Family().IsDomain() {
-				ip := w.Handler.resolveIP(w.Context, b.UDP.Address.Domain(), nil)
+				if ip := w.resolvedUDPAddr[b.UDP.Address.Domain()]; ip != nil {
-				if 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())