Improve compatibility for kTLS

common/ktls/ktls.go

@@ -3,8 +3,10 @@
 package ktls
 
 import (
+	"bytes"
 	"context"
 	"crypto/tls"
+	"errors"
 	"io"
 	"net"
 	"os"
@@ -15,6 +17,8 @@ import (
 	"github.com/sagernet/sing/common/logger"
 	N "github.com/sagernet/sing/common/network"
 	aTLS "github.com/sagernet/sing/common/tls"
+
+	"golang.org/x/sys/unix"
 )
 
 type Conn struct {
@@ -85,7 +89,7 @@ func (c *Conn) Upstream() any {
 	return c.Conn
 }
 
-func (c *Conn) SyscallConnForRead() syscall.Conn {
+func (c *Conn) SyscallConnForRead() syscall.RawConn {
 	if !c.kernelRx {
 		return nil
 	}
@@ -94,13 +98,34 @@ func (c *Conn) SyscallConnForRead() syscall.Conn {
 		return nil
 	}
 	c.logger.DebugContext(c.ctx, "ktls: RX splice requested")
-	return c.syscallConn
+	return c.rawSyscallConn
 }
 
-func (c *Conn) SyscallConnForWrite() syscall.Conn {
+func (c *Conn) HandleSyscallReadError(inputErr error) ([]byte, error) {
+	if errors.Is(inputErr, unix.EINVAL) {
+		err := c.readRecord()
+		if err != nil {
+			return nil, E.Cause(err, "ktls: handle non-application-data record")
+		}
+		var input bytes.Buffer
+		if c.rawConn.Input.Len() > 0 {
+			_, err = c.rawConn.Input.WriteTo(&input)
+			if err != nil {
+				return nil, err
+			}
+		}
+		return input.Bytes(), nil
+	} else if errors.Is(inputErr, unix.EBADMSG) {
+		return nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertBadRecordMAC))
+	} else {
+		return nil, E.Cause(inputErr, "ktls: unexpected errno")
+	}
+}
+
+func (c *Conn) SyscallConnForWrite() syscall.RawConn {
 	if !c.kernelTx {
 		return nil
 	}
 	c.logger.DebugContext(c.ctx, "ktls: TX splice requested")
-	return c.syscallConn
+	return c.rawSyscallConn
 }