diff --git a/common/bufio/conn.go b/common/bufio/conn.go
index ad3d722..ffa83ea 100644
--- a/common/bufio/conn.go
+++ b/common/bufio/conn.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
+	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/common/rw"
@@ -37,6 +38,11 @@ func needReadFromWrapper(dst io.ReaderFrom, src io.Reader) bool {
 }
 
 func Copy(dst io.Writer, src io.Reader) (n int64, err error) {
+	if src == nil {
+		return 0, E.New("nil reader")
+	} else if dst == nil {
+		return 0, E.New("nil writer")
+	}
 	src = N.UnwrapReader(src)
 	dst = N.UnwrapWriter(dst)
 	if wt, ok := src.(io.WriterTo); ok {
diff --git a/common/exceptions/error.go b/common/exceptions/error.go
index 0e33c6a..fb9316c 100644
--- a/common/exceptions/error.go
+++ b/common/exceptions/error.go
@@ -6,10 +6,11 @@ import (
 	"io"
 	"net"
 	"os"
+	"syscall"
+	_ "unsafe"
 
 	"github.com/sagernet/sing/common"
 	F "github.com/sagernet/sing/common/format"
-	"syscall"
 )
 
 type Handler interface {
@@ -45,10 +46,17 @@ func Errors(errors ...error) error {
 	}
 }
 
-func IsCanceled(err error) bool {
-	return IsMulti(err, context.Canceled, context.DeadlineExceeded)
+//go:linkname errCanceled net.errCanceled
+var errCanceled error
+
+func IsClosedOrCanceled(err error) bool {
+	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE, syscall.ECONNRESET, context.Canceled, context.DeadlineExceeded, errCanceled)
 }
 
 func IsClosed(err error) bool {
-	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE)
+	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE, syscall.ECONNRESET)
+}
+
+func IsCanceled(err error) bool {
+	return IsMulti(err, context.Canceled, context.DeadlineExceeded, errCanceled)
 }