diff --git a/app/proxyman/mux/mux.go b/app/proxyman/mux/mux.go
index 8db25918a..517fd0d3e 100644
--- a/app/proxyman/mux/mux.go
+++ b/app/proxyman/mux/mux.go
@@ -154,7 +154,7 @@ func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
 			return
 		}
 	}
-	if err := buf.PipeUntilEOF(signal.BackgroundTimer(), s.input, writer); err != nil {
+	if err := buf.Copy(signal.BackgroundTimer(), s.input, writer); err != nil {
 		log.Trace(newError("failed to fetch all input").Base(err))
 	}
 }
@@ -309,7 +309,7 @@ type ServerWorker struct {
 
 func handle(ctx context.Context, s *Session, output buf.Writer) {
 	writer := NewResponseWriter(s.ID, output)
-	if err := buf.PipeUntilEOF(signal.BackgroundTimer(), s.input, writer); err != nil {
+	if err := buf.Copy(signal.BackgroundTimer(), s.input, writer); err != nil {
 		log.Trace(newError("session ", s.ID, " ends: ").Base(err))
 	}
 	writer.Close()
diff --git a/common/buf/io.go b/common/buf/io.go
index a36158492..df18d95c6 100644
--- a/common/buf/io.go
+++ b/common/buf/io.go
@@ -40,9 +40,7 @@ func ReadFullFrom(reader io.Reader, size int) Supplier {
 	}
 }
 
-// Pipe dumps all payload from reader to writer, until an error occurs.
-// ActivityTimer gets updated as soon as there is a payload.
-func Pipe(timer signal.ActivityTimer, reader Reader, writer Writer) error {
+func copyInternal(timer signal.ActivityTimer, reader Reader, writer Writer) error {
 	for {
 		buffer, err := reader.Read()
 		if err != nil {
@@ -64,9 +62,10 @@ func Pipe(timer signal.ActivityTimer, reader Reader, writer Writer) error {
 	}
 }
 
-// PipeUntilEOF behaves the same as Pipe(). The only difference is PipeUntilEOF returns nil on EOF.
-func PipeUntilEOF(timer signal.ActivityTimer, reader Reader, writer Writer) error {
-	err := Pipe(timer, reader, writer)
+// Copy dumps all payload from reader to writer or stops when an error occurs.
+// ActivityTimer gets updated as soon as there is a payload.
+func Copy(timer signal.ActivityTimer, reader Reader, writer Writer) error {
+	err := copyInternal(timer, reader, writer)
 	if err != nil && errors.Cause(err) != io.EOF {
 		return err
 	}
diff --git a/proxy/dokodemo/dokodemo.go b/proxy/dokodemo/dokodemo.go
index 6519e897f..1c4a7716a 100644
--- a/proxy/dokodemo/dokodemo.go
+++ b/proxy/dokodemo/dokodemo.go
@@ -76,7 +76,7 @@ func (d *DokodemoDoor) Process(ctx context.Context, network net.Network, conn in
 
 		chunkReader := buf.NewReader(conn)
 
-		if err := buf.PipeUntilEOF(timer, chunkReader, inboundRay.InboundInput()); err != nil {
+		if err := buf.Copy(timer, chunkReader, inboundRay.InboundInput()); err != nil {
 			return newError("failed to transport request").Base(err)
 		}
 
@@ -86,7 +86,7 @@ func (d *DokodemoDoor) Process(ctx context.Context, network net.Network, conn in
 	responseDone := signal.ExecuteAsync(func() error {
 		v2writer := buf.NewWriter(conn)
 
-		if err := buf.PipeUntilEOF(timer, inboundRay.InboundOutput(), v2writer); err != nil {
+		if err := buf.Copy(timer, inboundRay.InboundOutput(), v2writer); err != nil {
 			return newError("failed to transport response").Base(err)
 		}
 		return nil
diff --git a/proxy/freedom/freedom.go b/proxy/freedom/freedom.go
index e815f6044..a2bd0182c 100644
--- a/proxy/freedom/freedom.go
+++ b/proxy/freedom/freedom.go
@@ -119,7 +119,7 @@ func (v *Handler) Process(ctx context.Context, outboundRay ray.OutboundRay, dial
 		} else {
 			writer = &seqWriter{writer: conn}
 		}
-		if err := buf.PipeUntilEOF(timer, input, writer); err != nil {
+		if err := buf.Copy(timer, input, writer); err != nil {
 			return newError("failed to process request").Base(err)
 		}
 		return nil
@@ -129,7 +129,7 @@ func (v *Handler) Process(ctx context.Context, outboundRay ray.OutboundRay, dial
 		defer output.Close()
 
 		v2reader := buf.NewReader(conn)
-		if err := buf.PipeUntilEOF(timer, v2reader, output); err != nil {
+		if err := buf.Copy(timer, v2reader, output); err != nil {
 			return newError("failed to process response").Base(err)
 		}
 		return nil
diff --git a/proxy/http/server.go b/proxy/http/server.go
index 65e835e7e..18f895780 100644
--- a/proxy/http/server.go
+++ b/proxy/http/server.go
@@ -152,7 +152,7 @@ func (s *Server) handleConnect(ctx context.Context, request *http.Request, reade
 		defer ray.InboundInput().Close()
 
 		v2reader := buf.NewReader(reader)
-		if err := buf.PipeUntilEOF(timer, v2reader, ray.InboundInput()); err != nil {
+		if err := buf.Copy(timer, v2reader, ray.InboundInput()); err != nil {
 			return err
 		}
 		return nil
@@ -160,7 +160,7 @@ func (s *Server) handleConnect(ctx context.Context, request *http.Request, reade
 
 	responseDone := signal.ExecuteAsync(func() error {
 		v2writer := buf.NewWriter(writer)
-		if err := buf.PipeUntilEOF(timer, ray.InboundOutput(), v2writer); err != nil {
+		if err := buf.Copy(timer, ray.InboundOutput(), v2writer); err != nil {
 			return err
 		}
 		return nil
diff --git a/proxy/shadowsocks/client.go b/proxy/shadowsocks/client.go
index 5da0d01c0..91cdea448 100644
--- a/proxy/shadowsocks/client.go
+++ b/proxy/shadowsocks/client.go
@@ -105,7 +105,7 @@ func (v *Client) Process(ctx context.Context, outboundRay ray.OutboundRay, diale
 		}
 
 		requestDone := signal.ExecuteAsync(func() error {
-			if err := buf.PipeUntilEOF(timer, outboundRay.OutboundInput(), bodyWriter); err != nil {
+			if err := buf.Copy(timer, outboundRay.OutboundInput(), bodyWriter); err != nil {
 				return err
 			}
 			return nil
@@ -119,7 +119,7 @@ func (v *Client) Process(ctx context.Context, outboundRay ray.OutboundRay, diale
 				return err
 			}
 
-			if err := buf.PipeUntilEOF(timer, responseReader, outboundRay.OutboundOutput()); err != nil {
+			if err := buf.Copy(timer, responseReader, outboundRay.OutboundOutput()); err != nil {
 				return err
 			}
 
@@ -141,7 +141,7 @@ func (v *Client) Process(ctx context.Context, outboundRay ray.OutboundRay, diale
 		}
 
 		requestDone := signal.ExecuteAsync(func() error {
-			if err := buf.PipeUntilEOF(timer, outboundRay.OutboundInput(), writer); err != nil {
+			if err := buf.Copy(timer, outboundRay.OutboundInput(), writer); err != nil {
 				return newError("failed to transport all UDP request").Base(err)
 			}
 			return nil
@@ -155,7 +155,7 @@ func (v *Client) Process(ctx context.Context, outboundRay ray.OutboundRay, diale
 				User:   user,
 			}
 
-			if err := buf.PipeUntilEOF(timer, reader, outboundRay.OutboundOutput()); err != nil {
+			if err := buf.Copy(timer, reader, outboundRay.OutboundOutput()); err != nil {
 				return newError("failed to transport all UDP response").Base(err)
 			}
 			return nil
diff --git a/proxy/shadowsocks/server.go b/proxy/shadowsocks/server.go
index f22a19f9b..6ced719ee 100644
--- a/proxy/shadowsocks/server.go
+++ b/proxy/shadowsocks/server.go
@@ -173,7 +173,7 @@ func (s *Server) handleConnection(ctx context.Context, conn internet.Connection,
 			return err
 		}
 
-		if err := buf.PipeUntilEOF(timer, ray.InboundOutput(), responseWriter); err != nil {
+		if err := buf.Copy(timer, ray.InboundOutput(), responseWriter); err != nil {
 			return newError("failed to transport all TCP response").Base(err)
 		}
 
@@ -183,7 +183,7 @@ func (s *Server) handleConnection(ctx context.Context, conn internet.Connection,
 	requestDone := signal.ExecuteAsync(func() error {
 		defer ray.InboundInput().Close()
 
-		if err := buf.PipeUntilEOF(timer, bodyReader, ray.InboundInput()); err != nil {
+		if err := buf.Copy(timer, bodyReader, ray.InboundInput()); err != nil {
 			return newError("failed to transport all TCP request").Base(err)
 		}
 		return nil
diff --git a/proxy/socks/client.go b/proxy/socks/client.go
index 6a18c09fd..97eaee6af 100644
--- a/proxy/socks/client.go
+++ b/proxy/socks/client.go
@@ -90,11 +90,11 @@ func (c *Client) Process(ctx context.Context, ray ray.OutboundRay, dialer proxy.
 	var responseFunc func() error
 	if request.Command == protocol.RequestCommandTCP {
 		requestFunc = func() error {
-			return buf.PipeUntilEOF(timer, ray.OutboundInput(), buf.NewWriter(conn))
+			return buf.Copy(timer, ray.OutboundInput(), buf.NewWriter(conn))
 		}
 		responseFunc = func() error {
 			defer ray.OutboundOutput().Close()
-			return buf.PipeUntilEOF(timer, buf.NewReader(conn), ray.OutboundOutput())
+			return buf.Copy(timer, buf.NewReader(conn), ray.OutboundOutput())
 		}
 	} else if request.Command == protocol.RequestCommandUDP {
 		udpConn, err := dialer.Dial(ctx, udpRequest.Destination())
@@ -103,12 +103,12 @@ func (c *Client) Process(ctx context.Context, ray ray.OutboundRay, dialer proxy.
 		}
 		defer udpConn.Close()
 		requestFunc = func() error {
-			return buf.PipeUntilEOF(timer, ray.OutboundInput(), &UDPWriter{request: request, writer: udpConn})
+			return buf.Copy(timer, ray.OutboundInput(), &UDPWriter{request: request, writer: udpConn})
 		}
 		responseFunc = func() error {
 			defer ray.OutboundOutput().Close()
 			reader := &UDPReader{reader: udpConn}
-			return buf.PipeUntilEOF(timer, reader, ray.OutboundOutput())
+			return buf.Copy(timer, reader, ray.OutboundOutput())
 		}
 	}
 
diff --git a/proxy/socks/server.go b/proxy/socks/server.go
index 5b3c2b5ea..cf6e08211 100644
--- a/proxy/socks/server.go
+++ b/proxy/socks/server.go
@@ -125,7 +125,7 @@ func (v *Server) transport(ctx context.Context, reader io.Reader, writer io.Writ
 		defer input.Close()
 
 		v2reader := buf.NewReader(reader)
-		if err := buf.PipeUntilEOF(timer, v2reader, input); err != nil {
+		if err := buf.Copy(timer, v2reader, input); err != nil {
 			return newError("failed to transport all TCP request").Base(err)
 		}
 		return nil
@@ -133,7 +133,7 @@ func (v *Server) transport(ctx context.Context, reader io.Reader, writer io.Writ
 
 	responseDone := signal.ExecuteAsync(func() error {
 		v2writer := buf.NewWriter(writer)
-		if err := buf.PipeUntilEOF(timer, output, v2writer); err != nil {
+		if err := buf.Copy(timer, output, v2writer); err != nil {
 			return newError("failed to transport all TCP response").Base(err)
 		}
 		return nil
diff --git a/proxy/vmess/inbound/inbound.go b/proxy/vmess/inbound/inbound.go
index 773b4a3e2..790a8fd5d 100644
--- a/proxy/vmess/inbound/inbound.go
+++ b/proxy/vmess/inbound/inbound.go
@@ -129,7 +129,7 @@ func transferRequest(timer signal.ActivityTimer, session *encoding.ServerSession
 	defer output.Close()
 
 	bodyReader := session.DecodeRequestBody(request, input)
-	if err := buf.PipeUntilEOF(timer, bodyReader, output); err != nil {
+	if err := buf.Copy(timer, bodyReader, output); err != nil {
 		return err
 	}
 	return nil
@@ -157,7 +157,7 @@ func transferResponse(timer signal.ActivityTimer, session *encoding.ServerSessio
 		}
 	}
 
-	if err := buf.PipeUntilEOF(timer, input, bodyWriter); err != nil {
+	if err := buf.Copy(timer, input, bodyWriter); err != nil {
 		return err
 	}
 
diff --git a/proxy/vmess/outbound/outbound.go b/proxy/vmess/outbound/outbound.go
index 544c4d322..d1584d5c7 100644
--- a/proxy/vmess/outbound/outbound.go
+++ b/proxy/vmess/outbound/outbound.go
@@ -123,7 +123,7 @@ func (v *Handler) Process(ctx context.Context, outboundRay ray.OutboundRay, dial
 			return err
 		}
 
-		if err := buf.PipeUntilEOF(timer, input, bodyWriter); err != nil {
+		if err := buf.Copy(timer, input, bodyWriter); err != nil {
 			return err
 		}
 
@@ -147,7 +147,7 @@ func (v *Handler) Process(ctx context.Context, outboundRay ray.OutboundRay, dial
 
 		reader.SetBuffered(false)
 		bodyReader := session.DecodeResponseBody(request, reader)
-		if err := buf.PipeUntilEOF(timer, bodyReader, output); err != nil {
+		if err := buf.Copy(timer, bodyReader, output); err != nil {
 			return err
 		}