XTLS Vision: Suppress outer CloseNotify after switching to direct copy (#6834)

https://github.com/XTLS/Xray-core/pull/6816#issuecomment-5828082031
https://github.com/XTLS/Xray-core/issues/6794#issuecomment-5847200576
https://github.com/XTLS/Xray-core/pull/6834#issuecomment-5860728689

Fixes https://github.com/XTLS/Xray-core/issues/6794#issuecomment-5754894283
Fixes https://github.com/XTLS/Xray-core/issues/6124#issuecomment-4439918073
Fixes https://github.com/XTLS/Xray-core/issues/4878#issuecomment-5754638401

---------

Co-authored-by: Artem Lytkin <146867384+4RH1T3CT0R7@users.noreply.github.com>

proxy/proxy.go

@@ -277,6 +277,7 @@ func (w *VisionReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 				w.ob.CanSpliceCopy = 1
 			}
 		}
+		SuppressOuterCloseNotify(w.conn)
 		readerConn, readCounter, _ := UnwrapRawConn(w.conn)
 		w.directReadCounter = readCounter
 		w.Reader = buf.NewReader(readerConn)
@@ -340,6 +341,7 @@ func (w *VisionWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
 			// 	w.ob.CanSpliceCopy = 1
 			// }
 		}
+		SuppressOuterCloseNotify(w.conn)
 		rawConn, _, writerCounter := UnwrapRawConn(w.conn)
 		w.Writer = buf.NewWriter(rawConn)
 		w.directWriteCounter = writerCounter
@@ -669,6 +671,19 @@ func XtlsFilterTls(buffer buf.MultiBuffer, trafficState *TrafficState, ctx conte
 	}
 }
 
+type CloseNotifySuppressor interface {
+	SuppressCloseNotify()
+}
+
+// Close our local TLS conn instance might send a incorrect close_notify alert
+// if the XTLS direct copy mode is enabled and cause TLS BAD_RECORD_MAC on users' browser
+// Close the underlying connection directly to avoid this issue.
+func SuppressOuterCloseNotify(conn net.Conn) {
+	if suppressor, ok := stat.TryUnwrapStatsConn(conn).(CloseNotifySuppressor); ok {
+		suppressor.SuppressCloseNotify()
+	}
+}
+
 // UnwrapRawConn support unwrap encryption, stats, mask wrappers, tls, utls, reality, proxyproto, uds-wrapper conn and get raw tcp/uds conn from it
 func UnwrapRawConn(conn net.Conn) (net.Conn, stats.Counter, stats.Counter) {
 	var readCounter, writerCounter stats.Counter

transport/internet/reality/reality.go

@@ -18,6 +18,7 @@ import (
 	"regexp"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 	"unsafe"
 
@@ -36,6 +37,18 @@ import (
 
 type Conn struct {
 	*reality.Conn
+	suppressCloseNotify atomic.Bool
+}
+
+func (c *Conn) SuppressCloseNotify() {
+	c.suppressCloseNotify.Store(true)
+}
+
+func (c *Conn) Close() error {
+	if c.suppressCloseNotify.Load() {
+		return c.Conn.NetConn().Close()
+	}
+	return c.Conn.Close()
 }
 
 func (c *Conn) HandshakeAddress() net.Address {
@@ -56,10 +69,22 @@ func Server(c net.Conn, config *reality.Config) (net.Conn, error) {
 
 type UConn struct {
 	*utls.UConn
-	Config     *Config
-	ServerName string
-	AuthKey    []byte
-	Verified   bool
+	Config              *Config
+	ServerName          string
+	AuthKey             []byte
+	Verified            bool
+	suppressCloseNotify atomic.Bool
+}
+
+func (c *UConn) SuppressCloseNotify() {
+	c.suppressCloseNotify.Store(true)
+}
+
+func (c *UConn) Close() error {
+	if c.suppressCloseNotify.Load() {
+		return c.NetConn().Close()
+	}
+	return c.UConn.Close()
 }
 
 func (c *UConn) HandshakeAddress() net.Address {

transport/internet/tls/tls.go

@@ -6,6 +6,7 @@ import (
 	"crypto/tls"
 	"math/big"
 	"slices"
+	"sync/atomic"
 	"time"
 
 	utls "github.com/refraction-networking/utls"
@@ -29,11 +30,19 @@ var (
 
 type Conn struct {
 	*tls.Conn
+	suppressCloseNotify atomic.Bool
 }
 
 const tlsCloseTimeout = 250 * time.Millisecond
 
+func (c *Conn) SuppressCloseNotify() {
+	c.suppressCloseNotify.Store(true)
+}
+
 func (c *Conn) Close() error {
+	if c.suppressCloseNotify.Load() {
+		return c.Conn.NetConn().Close()
+	}
 	timer := time.AfterFunc(tlsCloseTimeout, func() {
 		c.Conn.NetConn().Close()
 	})
@@ -74,11 +83,19 @@ func Server(c net.Conn, config *tls.Config) net.Conn {
 
 type UConn struct {
 	*utls.UConn
+	suppressCloseNotify atomic.Bool
 }
 
 var _ Interface = (*UConn)(nil)
 
+func (c *UConn) SuppressCloseNotify() {
+	c.suppressCloseNotify.Store(true)
+}
+
 func (c *UConn) Close() error {
+	if c.suppressCloseNotify.Load() {
+		return c.Conn.NetConn().Close()
+	}
 	timer := time.AfterFunc(tlsCloseTimeout, func() {
 		c.Conn.NetConn().Close()
 	})