diff --git a/service/shadowsocks.go b/service/shadowsocks.go
index 9137136d..23c17623 100644
--- a/service/shadowsocks.go
+++ b/service/shadowsocks.go
@@ -148,7 +148,7 @@ func (s *ssService) HandleAssociation(conn net.Conn) error {
 	if err != nil {
 		return fmt.Errorf("failed to handle association: %v", err)
 	}
-	HandleAssociation(conn, assoc)
+	HandleAssociation(assoc)
 	return nil
 }
 
diff --git a/service/udp.go b/service/udp.go
index 8cbfea6a..94f8430b 100644
--- a/service/udp.go
+++ b/service/udp.go
@@ -355,11 +355,11 @@ func (m *natmap) Close() error {
 	return err
 }
 
-func HandleAssociation(conn net.Conn, assoc PacketAssociation) { 
+func HandleAssociation(assoc PacketAssociation) { 
 	for {
 		lazySlice := readBufPool.LazySlice()
 		buf := lazySlice.Acquire()
-		n, err := conn.Read(buf)
+		n, err := assoc.Read(buf)
 		if errors.Is(err, net.ErrClosed) {
 			lazySlice.Release()
 			return
@@ -384,9 +384,13 @@ type PacketAssociation interface {
 	// released after the packet is processed.
 	HandlePacket(pkt []byte, lazySlice slicepool.LazySlice)
 
+	// Read reads data from the association.
+	Read(b []byte) (n int, err error)
+
 	// Done returns a channel that is closed when the association is closed.
 	Done() <-chan struct{}
 
+
 	// Close closes the association and releases any associated resources.
 	Close() error
 }