Socks: Fix unexpected rawConn copy

proxy/socks/server.go

@@ -75,6 +75,9 @@ func (s *Server) Process(ctx context.Context, network net.Network, conn stat.Con
 	inbound.User = &protocol.MemoryUser{
 		Level: s.config.UserLevel,
 	}
+	if isTransportConn(conn) {
+		inbound.CanSpliceCopy = 3
+	}
 
 	switch network {
 	case net.Network_TCP:
@@ -199,7 +202,9 @@ func (s *Server) transport(ctx context.Context, reader io.Reader, writer io.Writ
 	}
 
 	responseDone := func() error {
-		inbound.CanSpliceCopy = 1
+		if inbound.CanSpliceCopy == 2 {
+			inbound.CanSpliceCopy = 1
+		}
 		defer timer.SetTimeout(plcy.Timeouts.UplinkOnly)
 
 		v2writer := buf.NewWriter(writer)
@@ -259,7 +264,9 @@ func (s *Server) handleUDPPayload(ctx context.Context, conn stat.Connection, dis
 	if inbound != nil && inbound.Source.IsValid() {
 		errors.LogInfo(ctx, "client UDP connection from ", inbound.Source)
 	}
-	inbound.CanSpliceCopy = 1
+	if inbound.CanSpliceCopy == 2 {
+		inbound.CanSpliceCopy = 1
+	}
 
 	var dest *net.Destination
 
@@ -308,6 +315,20 @@ func (s *Server) handleUDPPayload(ctx context.Context, conn stat.Connection, dis
 	}
 }
 
+// isTransportConn return false if the conn is a raw tcp conn without transport or tls, can process splice copy
+func isTransportConn(conn stat.Connection) bool {
+	if conn != nil {
+		statConn, ok := conn.(*stat.CounterConnection)
+		if ok {
+			conn = statConn.Connection
+		}
+		if _, ok := conn.(*net.TCPConn); ok {
+			return false
+		}
+	}
+	return true
+}
+
 func init() {
 	common.Must(common.RegisterConfig((*ServerConfig)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		return NewServer(ctx, config.(*ServerConfig))