Add support for kTLS

Reference: https://gitlab.com/go-extension/tls

.github/workflows/build.yml

@@ -154,7 +154,7 @@ jobs:
           set -xeuo pipefail
           mkdir -p dist
           go build -v -trimpath -o dist/sing-box -tags "${BUILD_TAGS}" \
-          -ldflags '-s -buildid= -X github.com/sagernet/sing-box/constant.Version=${{ needs.calculate_version.outputs.version }}' \
+          -ldflags '-s -buildid= -X github.com/sagernet/sing-box/constant.Version=${{ needs.calculate_version.outputs.version }} -checklinkname=0' \
           ./cmd/sing-box
         env:
           CGO_ENABLED: "0"
@@ -174,7 +174,7 @@ jobs:
           export CXX="${CC}++"
           mkdir -p dist
           GOOS=$BUILD_GOOS GOARCH=$BUILD_GOARCH build go build -v -trimpath -o dist/sing-box -tags "${BUILD_TAGS}" \
-          -ldflags '-s -buildid= -X github.com/sagernet/sing-box/constant.Version=${{ needs.calculate_version.outputs.version }}' \
+          -ldflags '-s -buildid= -X github.com/sagernet/sing-box/constant.Version=${{ needs.calculate_version.outputs.version }} -checklinkname=0' \
           ./cmd/sing-box
         env:
           CGO_ENABLED: "1"

Dockerfile

@@ -15,7 +15,7 @@ RUN set -ex \
     && go build -v -trimpath -tags \
         "with_gvisor,with_quic,with_dhcp,with_wireguard,with_utls,with_acme,with_clash_api,with_tailscale" \
         -o /go/bin/sing-box \
-        -ldflags "-X \"github.com/sagernet/sing-box/constant.Version=$VERSION\" -s -w -buildid=" \
+        -ldflags "-X \"github.com/sagernet/sing-box/constant.Version=$VERSION\" -s -w -buildid= -checklinkname=0" \
         ./cmd/sing-box
 FROM --platform=$TARGETPLATFORM alpine AS dist
 LABEL maintainer="nekohasekai <contact-git@sekai.icu>"

cmd/internal/build_libbox/main.go

@@ -59,8 +59,8 @@ func init() {
 	if err != nil {
 		currentTag = "unknown"
 	}
-	sharedFlags = append(sharedFlags, "-ldflags", "-X github.com/sagernet/sing-box/constant.Version="+currentTag+" -s -w -buildid=")
+	sharedFlags = append(sharedFlags, "-ldflags", "-X github.com/sagernet/sing-box/constant.Version="+currentTag+" -s -w -buildid=  -checklinkname=0")
-	debugFlags = append(debugFlags, "-ldflags", "-X github.com/sagernet/sing-box/constant.Version="+currentTag)
+	debugFlags = append(debugFlags, "-ldflags", "-X github.com/sagernet/sing-box/constant.Version="+currentTag+" -checklinkname=0")
 
 	sharedTags = append(sharedTags, "with_gvisor", "with_quic", "with_wireguard", "with_utls", "with_clash_api", "with_conntrack")
 	macOSTags = append(macOSTags, "with_dhcp")
@@ -107,10 +107,10 @@ func buildAndroid() {
 	}
 
 	if !debugEnabled {
-		sharedFlags[3] = sharedFlags[3] + " -checklinkname=0"
+		// sharedFlags[3] = sharedFlags[3] + " -checklinkname=0"
 		args = append(args, sharedFlags...)
 	} else {
-		debugFlags[1] = debugFlags[1] + " -checklinkname=0"
+		// debugFlags[1] = debugFlags[1] + " -checklinkname=0"
 		args = append(args, debugFlags...)
 	}
 

common/badtls/raw_conn.go

@@ -0,0 +1,169 @@
+//go:build go1.25 && !without_badtls
+
+package badtls
+
+import (
+	"bytes"
+	"os"
+	"reflect"
+	"sync/atomic"
+	"unsafe"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/tls"
+)
+
+type RawConn struct {
+	pointer unsafe.Pointer
+	methods *Methods
+
+	IsClient            *bool
+	IsHandshakeComplete *atomic.Bool
+	Vers                *uint16
+	CipherSuite         *uint16
+
+	RawInput *bytes.Buffer
+	Input    *bytes.Reader
+	Hand     *bytes.Buffer
+
+	CloseNotifySent *bool
+	CloseNotifyErr  *error
+
+	In  *RawHalfConn
+	Out *RawHalfConn
+
+	BytesSent   *int64
+	PacketsSent *int64
+
+	ActiveCall *atomic.Int32
+}
+
+func NewRawConn(rawTLSConn tls.Conn) (*RawConn, error) {
+	var (
+		pointer unsafe.Pointer
+		methods *Methods
+		loaded  bool
+	)
+	for _, tlsCreator := range methodRegistry {
+		pointer, methods, loaded = tlsCreator(rawTLSConn)
+		if loaded {
+			break
+		}
+	}
+	if !loaded {
+		return nil, os.ErrInvalid
+	}
+
+	conn := &RawConn{
+		pointer: pointer,
+		methods: methods,
+	}
+
+	rawConn := reflect.Indirect(reflect.ValueOf(rawTLSConn))
+
+	rawIsClient := rawConn.FieldByName("isClient")
+	if !rawIsClient.IsValid() || rawIsClient.Kind() != reflect.Bool {
+		return nil, E.New("invalid Conn.isClient")
+	}
+	conn.IsClient = (*bool)(unsafe.Pointer(rawIsClient.UnsafeAddr()))
+
+	rawIsHandshakeComplete := rawConn.FieldByName("isHandshakeComplete")
+	if !rawIsHandshakeComplete.IsValid() || rawIsHandshakeComplete.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.isHandshakeComplete")
+	}
+	conn.IsHandshakeComplete = (*atomic.Bool)(unsafe.Pointer(rawIsHandshakeComplete.UnsafeAddr()))
+
+	rawVers := rawConn.FieldByName("vers")
+	if !rawVers.IsValid() || rawVers.Kind() != reflect.Uint16 {
+		return nil, E.New("invalid Conn.vers")
+	}
+	conn.Vers = (*uint16)(unsafe.Pointer(rawVers.UnsafeAddr()))
+
+	rawCipherSuite := rawConn.FieldByName("cipherSuite")
+	if !rawCipherSuite.IsValid() || rawCipherSuite.Kind() != reflect.Uint16 {
+		return nil, E.New("invalid Conn.cipherSuite")
+	}
+	conn.CipherSuite = (*uint16)(unsafe.Pointer(rawCipherSuite.UnsafeAddr()))
+
+	rawRawInput := rawConn.FieldByName("rawInput")
+	if !rawRawInput.IsValid() || rawRawInput.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.rawInput")
+	}
+	conn.RawInput = (*bytes.Buffer)(unsafe.Pointer(rawRawInput.UnsafeAddr()))
+
+	rawInput := rawConn.FieldByName("input")
+	if !rawInput.IsValid() || rawInput.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.input")
+	}
+	conn.Input = (*bytes.Reader)(unsafe.Pointer(rawInput.UnsafeAddr()))
+
+	rawHand := rawConn.FieldByName("hand")
+	if !rawHand.IsValid() || rawHand.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.hand")
+	}
+	conn.Hand = (*bytes.Buffer)(unsafe.Pointer(rawHand.UnsafeAddr()))
+
+	rawCloseNotifySent := rawConn.FieldByName("closeNotifySent")
+	if !rawCloseNotifySent.IsValid() || rawCloseNotifySent.Kind() != reflect.Bool {
+		return nil, E.New("invalid Conn.closeNotifySent")
+	}
+	conn.CloseNotifySent = (*bool)(unsafe.Pointer(rawCloseNotifySent.UnsafeAddr()))
+
+	rawCloseNotifyErr := rawConn.FieldByName("closeNotifyErr")
+	if !rawCloseNotifyErr.IsValid() || rawCloseNotifyErr.Kind() != reflect.Interface {
+		return nil, E.New("invalid Conn.closeNotifyErr")
+	}
+	conn.CloseNotifyErr = (*error)(unsafe.Pointer(rawCloseNotifyErr.UnsafeAddr()))
+
+	rawIn := rawConn.FieldByName("in")
+	if !rawIn.IsValid() || rawIn.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.in")
+	}
+	halfIn, err := NewRawHalfConn(rawIn, methods)
+	if err != nil {
+		return nil, E.Cause(err, "invalid Conn.in")
+	}
+	conn.In = halfIn
+
+	rawOut := rawConn.FieldByName("out")
+	if !rawOut.IsValid() || rawOut.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.out")
+	}
+	halfOut, err := NewRawHalfConn(rawOut, methods)
+	if err != nil {
+		return nil, E.Cause(err, "invalid Conn.out")
+	}
+	conn.Out = halfOut
+
+	rawBytesSent := rawConn.FieldByName("bytesSent")
+	if !rawBytesSent.IsValid() || rawBytesSent.Kind() != reflect.Int64 {
+		return nil, E.New("invalid Conn.bytesSent")
+	}
+	conn.BytesSent = (*int64)(unsafe.Pointer(rawBytesSent.UnsafeAddr()))
+
+	rawPacketsSent := rawConn.FieldByName("packetsSent")
+	if !rawPacketsSent.IsValid() || rawPacketsSent.Kind() != reflect.Int64 {
+		return nil, E.New("invalid Conn.packetsSent")
+	}
+	conn.PacketsSent = (*int64)(unsafe.Pointer(rawPacketsSent.UnsafeAddr()))
+
+	rawActiveCall := rawConn.FieldByName("activeCall")
+	if !rawActiveCall.IsValid() || rawActiveCall.Kind() != reflect.Struct {
+		return nil, E.New("invalid Conn.activeCall")
+	}
+	conn.ActiveCall = (*atomic.Int32)(unsafe.Pointer(rawActiveCall.UnsafeAddr()))
+
+	return conn, nil
+}
+
+func (c *RawConn) ReadRecord() error {
+	return c.methods.readRecord(c.pointer)
+}
+
+func (c *RawConn) HandlePostHandshakeMessage() error {
+	return c.methods.handlePostHandshakeMessage(c.pointer)
+}
+
+func (c *RawConn) WriteRecordLocked(typ uint16, data []byte) (int, error) {
+	return c.methods.writeRecordLocked(c.pointer, typ, data)
+}

common/badtls/raw_half_conn.go

@@ -0,0 +1,121 @@
+//go:build go1.25 && !without_badtls
+
+package badtls
+
+import (
+	"hash"
+	"reflect"
+	"sync"
+	"unsafe"
+
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+type RawHalfConn struct {
+	pointer unsafe.Pointer
+	methods *Methods
+	*sync.Mutex
+	Err           *error
+	Version       *uint16
+	Cipher        *any
+	Seq           *[8]byte
+	ScratchBuf    *[13]byte
+	TrafficSecret *[]byte
+	Mac           *hash.Hash
+	RawKey        *[]byte
+	RawIV         *[]byte
+	RawMac        *[]byte
+}
+
+func NewRawHalfConn(rawHalfConn reflect.Value, methods *Methods) (*RawHalfConn, error) {
+	halfConn := &RawHalfConn{
+		pointer: (unsafe.Pointer)(rawHalfConn.UnsafeAddr()),
+		methods: methods,
+	}
+
+	rawMutex := rawHalfConn.FieldByName("Mutex")
+	if !rawMutex.IsValid() || rawMutex.Kind() != reflect.Struct {
+		return nil, E.New("badtls: invalid halfConn.Mutex")
+	}
+	halfConn.Mutex = (*sync.Mutex)(unsafe.Pointer(rawMutex.UnsafeAddr()))
+
+	rawErr := rawHalfConn.FieldByName("err")
+	if !rawErr.IsValid() || rawErr.Kind() != reflect.Interface {
+		return nil, E.New("badtls: invalid halfConn.err")
+	}
+	halfConn.Err = (*error)(unsafe.Pointer(rawErr.UnsafeAddr()))
+
+	rawVersion := rawHalfConn.FieldByName("version")
+	if !rawVersion.IsValid() || rawVersion.Kind() != reflect.Uint16 {
+		return nil, E.New("badtls: invalid halfConn.version")
+	}
+	halfConn.Version = (*uint16)(unsafe.Pointer(rawVersion.UnsafeAddr()))
+
+	rawCipher := rawHalfConn.FieldByName("cipher")
+	if !rawCipher.IsValid() || rawCipher.Kind() != reflect.Interface {
+		return nil, E.New("badtls: invalid halfConn.cipher")
+	}
+	halfConn.Cipher = (*any)(unsafe.Pointer(rawCipher.UnsafeAddr()))
+
+	rawSeq := rawHalfConn.FieldByName("seq")
+	if !rawSeq.IsValid() || rawSeq.Kind() != reflect.Array || rawSeq.Len() != 8 || rawSeq.Type().Elem().Kind() != reflect.Uint8 {
+		return nil, E.New("badtls: invalid halfConn.seq")
+	}
+	halfConn.Seq = (*[8]byte)(unsafe.Pointer(rawSeq.UnsafeAddr()))
+
+	rawScratchBuf := rawHalfConn.FieldByName("scratchBuf")
+	if !rawScratchBuf.IsValid() || rawScratchBuf.Kind() != reflect.Array || rawScratchBuf.Len() != 13 || rawScratchBuf.Type().Elem().Kind() != reflect.Uint8 {
+		return nil, E.New("badtls: invalid halfConn.scratchBuf")
+	}
+	halfConn.ScratchBuf = (*[13]byte)(unsafe.Pointer(rawScratchBuf.UnsafeAddr()))
+
+	rawTrafficSecret := rawHalfConn.FieldByName("trafficSecret")
+	if !rawTrafficSecret.IsValid() || rawTrafficSecret.Kind() != reflect.Slice || rawTrafficSecret.Type().Elem().Kind() != reflect.Uint8 {
+		return nil, E.New("badtls: invalid halfConn.trafficSecret")
+	}
+	halfConn.TrafficSecret = (*[]byte)(unsafe.Pointer(rawTrafficSecret.UnsafeAddr()))
+
+	rawMac := rawHalfConn.FieldByName("mac")
+	if !rawMac.IsValid() || rawMac.Kind() != reflect.Interface {
+		return nil, E.New("badtls: invalid halfConn.mac")
+	}
+	halfConn.Mac = (*hash.Hash)(unsafe.Pointer(rawMac.UnsafeAddr()))
+
+	rawKey := rawHalfConn.FieldByName("rawKey")
+	if rawKey.IsValid() {
+		if /*!rawKey.IsValid() || */ rawKey.Kind() != reflect.Slice || rawKey.Type().Elem().Kind() != reflect.Uint8 {
+			return nil, E.New("badtls: invalid halfConn.rawKey")
+		}
+		halfConn.RawKey = (*[]byte)(unsafe.Pointer(rawKey.UnsafeAddr()))
+
+		rawIV := rawHalfConn.FieldByName("rawIV")
+		if !rawIV.IsValid() || rawIV.Kind() != reflect.Slice || rawIV.Type().Elem().Kind() != reflect.Uint8 {
+			return nil, E.New("badtls: invalid halfConn.rawIV")
+		}
+		halfConn.RawIV = (*[]byte)(unsafe.Pointer(rawIV.UnsafeAddr()))
+
+		rawMAC := rawHalfConn.FieldByName("rawMac")
+		if !rawMAC.IsValid() || rawMAC.Kind() != reflect.Slice || rawMAC.Type().Elem().Kind() != reflect.Uint8 {
+			return nil, E.New("badtls: invalid halfConn.rawMac")
+		}
+		halfConn.RawMac = (*[]byte)(unsafe.Pointer(rawMAC.UnsafeAddr()))
+	}
+
+	return halfConn, nil
+}
+
+func (hc *RawHalfConn) Decrypt(record []byte) ([]byte, uint8, error) {
+	return hc.methods.decrypt(hc.pointer, record)
+}
+
+func (hc *RawHalfConn) SetErrorLocked(err error) error {
+	return hc.methods.setErrorLocked(hc.pointer, err)
+}
+
+func (hc *RawHalfConn) SetTrafficSecret(suite unsafe.Pointer, level int, secret []byte) {
+	hc.methods.setTrafficSecret(hc.pointer, suite, level, secret)
+}
+
+func (hc *RawHalfConn) ExplicitNonceLen() int {
+	return hc.methods.explicitNonceLen(hc.pointer)
+}

common/badtls/read_wait.go

@@ -1,18 +1,9 @@
-//go:build go1.21 && !without_badtls
+//go:build go1.25 && !without_badtls
 
 package badtls
 
 import (
-	"bytes"
-	"context"
-	"net"
-	"os"
-	"reflect"
-	"sync"
-	"unsafe"
-
 	"github.com/sagernet/sing/common/buf"
-	E "github.com/sagernet/sing/common/exceptions"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/common/tls"
 )
@@ -21,63 +12,18 @@ var _ N.ReadWaiter = (*ReadWaitConn)(nil)
 
 type ReadWaitConn struct {
 	tls.Conn
-	halfAccess                    *sync.Mutex
+	rawConn         *RawConn
-	rawInput                      *bytes.Buffer
+	readWaitOptions N.ReadWaitOptions
-	input                         *bytes.Reader
-	hand                          *bytes.Buffer
-	readWaitOptions               N.ReadWaitOptions
-	tlsReadRecord                 func() error
-	tlsHandlePostHandshakeMessage func() error
 }
 
 func NewReadWaitConn(conn tls.Conn) (tls.Conn, error) {
-	var (
+	rawConn, err := NewRawConn(conn)
-		loaded                        bool
+	if err != nil {
-		tlsReadRecord                 func() error
+		return nil, err
-		tlsHandlePostHandshakeMessage func() error
-	)
-	for _, tlsCreator := range tlsRegistry {
-		loaded, tlsReadRecord, tlsHandlePostHandshakeMessage = tlsCreator(conn)
-		if loaded {
-			break
-		}
 	}
-	if !loaded {
-		return nil, os.ErrInvalid
-	}
-	rawConn := reflect.Indirect(reflect.ValueOf(conn))
-	rawHalfConn := rawConn.FieldByName("in")
-	if !rawHalfConn.IsValid() || rawHalfConn.Kind() != reflect.Struct {
-		return nil, E.New("badtls: invalid half conn")
-	}
-	rawHalfMutex := rawHalfConn.FieldByName("Mutex")
-	if !rawHalfMutex.IsValid() || rawHalfMutex.Kind() != reflect.Struct {
-		return nil, E.New("badtls: invalid half mutex")
-	}
-	halfAccess := (*sync.Mutex)(unsafe.Pointer(rawHalfMutex.UnsafeAddr()))
-	rawRawInput := rawConn.FieldByName("rawInput")
-	if !rawRawInput.IsValid() || rawRawInput.Kind() != reflect.Struct {
-		return nil, E.New("badtls: invalid raw input")
-	}
-	rawInput := (*bytes.Buffer)(unsafe.Pointer(rawRawInput.UnsafeAddr()))
-	rawInput0 := rawConn.FieldByName("input")
-	if !rawInput0.IsValid() || rawInput0.Kind() != reflect.Struct {
-		return nil, E.New("badtls: invalid input")
-	}
-	input := (*bytes.Reader)(unsafe.Pointer(rawInput0.UnsafeAddr()))
-	rawHand := rawConn.FieldByName("hand")
-	if !rawHand.IsValid() || rawHand.Kind() != reflect.Struct {
-		return nil, E.New("badtls: invalid hand")
-	}
-	hand := (*bytes.Buffer)(unsafe.Pointer(rawHand.UnsafeAddr()))
 	return &ReadWaitConn{
-		Conn:                          conn,
+		Conn:    conn,
-		halfAccess:                    halfAccess,
+		rawConn: rawConn,
-		rawInput:                      rawInput,
-		input:                         input,
-		hand:                          hand,
-		tlsReadRecord:                 tlsReadRecord,
-		tlsHandlePostHandshakeMessage: tlsHandlePostHandshakeMessage,
 	}, nil
 }
 
@@ -87,36 +33,36 @@ func (c *ReadWaitConn) InitializeReadWaiter(options N.ReadWaitOptions) (needCopy
 }
 
 func (c *ReadWaitConn) WaitReadBuffer() (buffer *buf.Buffer, err error) {
-	err = c.HandshakeContext(context.Background())
+	//err = c.HandshakeContext(context.Background())
-	if err != nil {
+	//if err != nil {
-		return
+	//	return
-	}
+	//}
-	c.halfAccess.Lock()
+	c.rawConn.In.Lock()
-	defer c.halfAccess.Unlock()
+	defer c.rawConn.In.Unlock()
-	for c.input.Len() == 0 {
+	for c.rawConn.Input.Len() == 0 {
-		err = c.tlsReadRecord()
+		err = c.rawConn.ReadRecord()
 		if err != nil {
 			return
 		}
-		for c.hand.Len() > 0 {
+		for c.rawConn.Hand.Len() > 0 {
-			err = c.tlsHandlePostHandshakeMessage()
+			err = c.rawConn.HandlePostHandshakeMessage()
 			if err != nil {
 				return
 			}
 		}
 	}
 	buffer = c.readWaitOptions.NewBuffer()
-	n, err := c.input.Read(buffer.FreeBytes())
+	n, err := c.rawConn.Input.Read(buffer.FreeBytes())
 	if err != nil {
 		buffer.Release()
 		return
 	}
 	buffer.Truncate(n)
 
-	if n != 0 && c.input.Len() == 0 && c.rawInput.Len() > 0 &&
+	if n != 0 && c.rawConn.Input.Len() == 0 && c.rawConn.Input.Len() > 0 &&
-		// recordType(c.rawInput.Bytes()[0]) == recordTypeAlert {
+		// recordType(c.RawInput.Bytes()[0]) == recordTypeAlert {
-		c.rawInput.Bytes()[0] == 21 {
+		c.rawConn.RawInput.Bytes()[0] == 21 {
-		_ = c.tlsReadRecord()
+		_ = c.rawConn.ReadRecord()
 		// return n, err // will be io.EOF on closeNotify
 	}
 
@@ -131,25 +77,3 @@ func (c *ReadWaitConn) Upstream() any {
 func (c *ReadWaitConn) ReaderReplaceable() bool {
 	return true
 }
-
-var tlsRegistry []func(conn net.Conn) (loaded bool, tlsReadRecord func() error, tlsHandlePostHandshakeMessage func() error)
-
-func init() {
-	tlsRegistry = append(tlsRegistry, func(conn net.Conn) (loaded bool, tlsReadRecord func() error, tlsHandlePostHandshakeMessage func() error) {
-		tlsConn, loaded := conn.(*tls.STDConn)
-		if !loaded {
-			return
-		}
-		return true, func() error {
-				return stdTLSReadRecord(tlsConn)
-			}, func() error {
-				return stdTLSHandlePostHandshakeMessage(tlsConn)
-			}
-	})
-}
-
-//go:linkname stdTLSReadRecord crypto/tls.(*Conn).readRecord
-func stdTLSReadRecord(c *tls.STDConn) error
-
-//go:linkname stdTLSHandlePostHandshakeMessage crypto/tls.(*Conn).handlePostHandshakeMessage
-func stdTLSHandlePostHandshakeMessage(c *tls.STDConn) error

common/badtls/read_wait_stub.go

@@ -1,4 +1,4 @@
-//go:build !go1.21 || without_badtls
+//go:build !go1.25 || without_badtls
 
 package badtls
 

common/badtls/read_wait_utls.go

@@ -1,36 +0,0 @@
-//go:build go1.21 && !without_badtls && with_utls
-
-package badtls
-
-import (
-	"net"
-	_ "unsafe"
-
-	"github.com/metacubex/utls"
-)
-
-func init() {
-	tlsRegistry = append(tlsRegistry, func(conn net.Conn) (loaded bool, tlsReadRecord func() error, tlsHandlePostHandshakeMessage func() error) {
-		switch tlsConn := conn.(type) {
-		case *tls.UConn:
-			return true, func() error {
-					return utlsReadRecord(tlsConn.Conn)
-				}, func() error {
-					return utlsHandlePostHandshakeMessage(tlsConn.Conn)
-				}
-		case *tls.Conn:
-			return true, func() error {
-					return utlsReadRecord(tlsConn)
-				}, func() error {
-					return utlsHandlePostHandshakeMessage(tlsConn)
-				}
-		}
-		return
-	})
-}
-
-//go:linkname utlsReadRecord github.com/metacubex/utls.(*Conn).readRecord
-func utlsReadRecord(c *tls.Conn) error
-
-//go:linkname utlsHandlePostHandshakeMessage github.com/metacubex/utls.(*Conn).handlePostHandshakeMessage
-func utlsHandlePostHandshakeMessage(c *tls.Conn) error

common/badtls/registry.go

@@ -0,0 +1,62 @@
+//go:build go1.25 && !without_badtls
+
+package badtls
+
+import (
+	"crypto/tls"
+	"net"
+	"unsafe"
+)
+
+type Methods struct {
+	readRecord                 func(c unsafe.Pointer) error
+	handlePostHandshakeMessage func(c unsafe.Pointer) error
+	writeRecordLocked          func(c unsafe.Pointer, typ uint16, data []byte) (int, error)
+
+	setErrorLocked   func(hc unsafe.Pointer, err error) error
+	decrypt          func(hc unsafe.Pointer, record []byte) ([]byte, uint8, error)
+	setTrafficSecret func(hc unsafe.Pointer, suite unsafe.Pointer, level int, secret []byte)
+	explicitNonceLen func(hc unsafe.Pointer) int
+}
+
+var methodRegistry []func(conn net.Conn) (unsafe.Pointer, *Methods, bool)
+
+func init() {
+	methodRegistry = append(methodRegistry, func(conn net.Conn) (unsafe.Pointer, *Methods, bool) {
+		tlsConn, loaded := conn.(*tls.Conn)
+		if !loaded {
+			return nil, nil, false
+		}
+		return unsafe.Pointer(tlsConn), &Methods{
+			readRecord:                 stdTLSReadRecord,
+			handlePostHandshakeMessage: stdTLSHandlePostHandshakeMessage,
+			writeRecordLocked:          stdWriteRecordLocked,
+
+			setErrorLocked:   stdSetErrorLocked,
+			decrypt:          stdDecrypt,
+			setTrafficSecret: stdSetTrafficSecret,
+			explicitNonceLen: stdExplicitNonceLen,
+		}, true
+	})
+}
+
+//go:linkname stdTLSReadRecord crypto/tls.(*Conn).readRecord
+func stdTLSReadRecord(c unsafe.Pointer) error
+
+//go:linkname stdTLSHandlePostHandshakeMessage crypto/tls.(*Conn).handlePostHandshakeMessage
+func stdTLSHandlePostHandshakeMessage(c unsafe.Pointer) error
+
+//go:linkname stdWriteRecordLocked crypto/tls.(*Conn).writeRecordLocked
+func stdWriteRecordLocked(c unsafe.Pointer, typ uint16, data []byte) (int, error)
+
+//go:linkname stdSetErrorLocked crypto/tls.(*halfConn).setErrorLocked
+func stdSetErrorLocked(hc unsafe.Pointer, err error) error
+
+//go:linkname stdDecrypt crypto/tls.(*halfConn).decrypt
+func stdDecrypt(hc unsafe.Pointer, record []byte) ([]byte, uint8, error)
+
+//go:linkname stdSetTrafficSecret crypto/tls.(*halfConn).setTrafficSecret
+func stdSetTrafficSecret(hc unsafe.Pointer, suite unsafe.Pointer, level int, secret []byte)
+
+//go:linkname stdExplicitNonceLen crypto/tls.(*halfConn).explicitNonceLen
+func stdExplicitNonceLen(hc unsafe.Pointer) int

common/badtls/registry_utls.go

@@ -0,0 +1,56 @@
+//go:build go1.25 && !without_badtls
+
+package badtls
+
+import (
+	"net"
+	"unsafe"
+
+	N "github.com/sagernet/sing/common/network"
+
+	"github.com/metacubex/utls"
+)
+
+func init() {
+	methodRegistry = append(methodRegistry, func(conn net.Conn) (unsafe.Pointer, *Methods, bool) {
+		var pointer unsafe.Pointer
+		if uConn, loaded := N.CastReader[*tls.Conn](conn); loaded {
+			pointer = unsafe.Pointer(uConn)
+		} else if uConn, loaded := N.CastReader[*tls.UConn](conn); loaded {
+			pointer = unsafe.Pointer(uConn.Conn)
+		} else {
+			return nil, nil, false
+		}
+		return pointer, &Methods{
+			readRecord:                 utlsReadRecord,
+			handlePostHandshakeMessage: utlsHandlePostHandshakeMessage,
+			writeRecordLocked:          utlsWriteRecordLocked,
+
+			setErrorLocked:   utlsSetErrorLocked,
+			decrypt:          utlsDecrypt,
+			setTrafficSecret: utlsSetTrafficSecret,
+			explicitNonceLen: utlsExplicitNonceLen,
+		}, true
+	})
+}
+
+//go:linkname utlsReadRecord github.com/metacubex/utls.(*Conn).readRecord
+func utlsReadRecord(c unsafe.Pointer) error
+
+//go:linkname utlsHandlePostHandshakeMessage github.com/metacubex/utls.(*Conn).handlePostHandshakeMessage
+func utlsHandlePostHandshakeMessage(c unsafe.Pointer) error
+
+//go:linkname utlsWriteRecordLocked github.com/metacubex/utls.(*Conn).writeRecordLocked
+func utlsWriteRecordLocked(hc unsafe.Pointer, typ uint16, data []byte) (int, error)
+
+//go:linkname utlsSetErrorLocked github.com/metacubex/utls.(*halfConn).setErrorLocked
+func utlsSetErrorLocked(hc unsafe.Pointer, err error) error
+
+//go:linkname utlsDecrypt github.com/metacubex/utls.(*halfConn).decrypt
+func utlsDecrypt(hc unsafe.Pointer, record []byte) ([]byte, uint8, error)
+
+//go:linkname utlsSetTrafficSecret github.com/metacubex/utls.(*halfConn).setTrafficSecret
+func utlsSetTrafficSecret(hc unsafe.Pointer, suite unsafe.Pointer, level int, secret []byte)
+
+//go:linkname utlsExplicitNonceLen github.com/metacubex/utls.(*halfConn).explicitNonceLen
+func utlsExplicitNonceLen(hc unsafe.Pointer) int

common/ktls/ktls.go

@@ -0,0 +1,84 @@
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/tls"
+	"io"
+	"net"
+	"os"
+	"syscall"
+
+	"github.com/sagernet/sing-box/common/badtls"
+	// C "github.com/sagernet/sing-box/constant"
+	E "github.com/sagernet/sing/common/exceptions"
+	N "github.com/sagernet/sing/common/network"
+	aTLS "github.com/sagernet/sing/common/tls"
+)
+
+type Conn struct {
+	aTLS.Conn
+	conn            net.Conn
+	rawConn         *badtls.RawConn
+	rawSyscallConn  syscall.RawConn
+	readWaitOptions N.ReadWaitOptions
+	kernelTx        bool
+	kernelRx        bool
+	tmp             [16]byte
+}
+
+func NewConn(conn aTLS.Conn, txOffload, rxOffload bool) (aTLS.Conn, error) {
+	syscallConn, isSyscallConn := N.CastReader[interface {
+		io.Reader
+		syscall.Conn
+	}](conn.NetConn())
+	if !isSyscallConn {
+		return nil, os.ErrInvalid
+	}
+	rawSyscallConn, err := syscallConn.SyscallConn()
+	if err != nil {
+		return nil, err
+	}
+	rawConn, err := badtls.NewRawConn(conn)
+	if err != nil {
+		return nil, err
+	}
+	if *rawConn.Vers != tls.VersionTLS13 {
+		return nil, os.ErrInvalid
+	}
+	for rawConn.RawInput.Len() > 0 {
+		err = rawConn.ReadRecord()
+		if err != nil {
+			return nil, err
+		}
+		for rawConn.Hand.Len() > 0 {
+			err = rawConn.HandlePostHandshakeMessage()
+			if err != nil {
+				return nil, E.Cause(err, "ktls: failed to handle post-handshake messages")
+			}
+		}
+	}
+	kConn := &Conn{
+		Conn:           conn,
+		conn:           conn.NetConn(),
+		rawConn:        rawConn,
+		rawSyscallConn: rawSyscallConn,
+	}
+	err = kConn.setupKernel(txOffload, rxOffload)
+	if err != nil {
+		return nil, err
+	}
+	return kConn, nil
+}
+
+func (c *Conn) Upstream() any {
+	return c.conn
+}
+
+func (c *Conn) ReaderReplaceable() bool {
+	return c.kernelRx
+}
+
+func (c *Conn) WriterReplaceable() bool {
+	return c.kernelTx
+}

common/ktls/ktls_alert.go

@@ -0,0 +1,80 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/tls"
+	"net"
+)
+
+const (
+	// alert level
+	alertLevelWarning = 1
+	alertLevelError   = 2
+)
+
+const (
+	alertCloseNotify                  = 0
+	alertUnexpectedMessage            = 10
+	alertBadRecordMAC                 = 20
+	alertDecryptionFailed             = 21
+	alertRecordOverflow               = 22
+	alertDecompressionFailure         = 30
+	alertHandshakeFailure             = 40
+	alertBadCertificate               = 42
+	alertUnsupportedCertificate       = 43
+	alertCertificateRevoked           = 44
+	alertCertificateExpired           = 45
+	alertCertificateUnknown           = 46
+	alertIllegalParameter             = 47
+	alertUnknownCA                    = 48
+	alertAccessDenied                 = 49
+	alertDecodeError                  = 50
+	alertDecryptError                 = 51
+	alertExportRestriction            = 60
+	alertProtocolVersion              = 70
+	alertInsufficientSecurity         = 71
+	alertInternalError                = 80
+	alertInappropriateFallback        = 86
+	alertUserCanceled                 = 90
+	alertNoRenegotiation              = 100
+	alertMissingExtension             = 109
+	alertUnsupportedExtension         = 110
+	alertCertificateUnobtainable      = 111
+	alertUnrecognizedName             = 112
+	alertBadCertificateStatusResponse = 113
+	alertBadCertificateHashValue      = 114
+	alertUnknownPSKIdentity           = 115
+	alertCertificateRequired          = 116
+	alertNoApplicationProtocol        = 120
+	alertECHRequired                  = 121
+)
+
+func (c *Conn) sendAlertLocked(err uint8) error {
+	switch err {
+	case alertNoRenegotiation, alertCloseNotify:
+		c.tmp[0] = alertLevelWarning
+	default:
+		c.tmp[0] = alertLevelError
+	}
+	c.tmp[1] = byte(err)
+
+	_, writeErr := c.writeRecordLocked(recordTypeAlert, c.tmp[0:2])
+	if err == alertCloseNotify {
+		// closeNotify is a special case in that it isn't an error.
+		return writeErr
+	}
+
+	return c.rawConn.Out.SetErrorLocked(&net.OpError{Op: "local error", Err: tls.AlertError(err)})
+}
+
+// sendAlert sends a TLS alert message.
+func (c *Conn) sendAlert(err uint8) error {
+	c.rawConn.Out.Lock()
+	defer c.rawConn.Out.Unlock()
+	return c.sendAlertLocked(err)
+}

common/ktls/ktls_cipher_suites_linux.go

@@ -0,0 +1,326 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/tls"
+	"unsafe"
+
+	"github.com/sagernet/sing-box/common/badtls"
+)
+
+type kernelCryptoCipherType uint16
+
+const (
+	TLS_CIPHER_AES_GCM_128              kernelCryptoCipherType = 51
+	TLS_CIPHER_AES_GCM_128_IV_SIZE      kernelCryptoCipherType = 8
+	TLS_CIPHER_AES_GCM_128_KEY_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_AES_GCM_128_SALT_SIZE    kernelCryptoCipherType = 4
+	TLS_CIPHER_AES_GCM_128_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	TLS_CIPHER_AES_GCM_256              kernelCryptoCipherType = 52
+	TLS_CIPHER_AES_GCM_256_IV_SIZE      kernelCryptoCipherType = 8
+	TLS_CIPHER_AES_GCM_256_KEY_SIZE     kernelCryptoCipherType = 32
+	TLS_CIPHER_AES_GCM_256_SALT_SIZE    kernelCryptoCipherType = 4
+	TLS_CIPHER_AES_GCM_256_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_AES_GCM_256_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	TLS_CIPHER_AES_CCM_128              kernelCryptoCipherType = 53
+	TLS_CIPHER_AES_CCM_128_IV_SIZE      kernelCryptoCipherType = 8
+	TLS_CIPHER_AES_CCM_128_KEY_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_AES_CCM_128_SALT_SIZE    kernelCryptoCipherType = 4
+	TLS_CIPHER_AES_CCM_128_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	TLS_CIPHER_CHACHA20_POLY1305              kernelCryptoCipherType = 54
+	TLS_CIPHER_CHACHA20_POLY1305_IV_SIZE      kernelCryptoCipherType = 12
+	TLS_CIPHER_CHACHA20_POLY1305_KEY_SIZE     kernelCryptoCipherType = 32
+	TLS_CIPHER_CHACHA20_POLY1305_SALT_SIZE    kernelCryptoCipherType = 0
+	TLS_CIPHER_CHACHA20_POLY1305_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_CHACHA20_POLY1305_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	// TLS_CIPHER_SM4_GCM              kernelCryptoCipherType = 55
+	// TLS_CIPHER_SM4_GCM_IV_SIZE      kernelCryptoCipherType = 8
+	// TLS_CIPHER_SM4_GCM_KEY_SIZE     kernelCryptoCipherType = 16
+	// TLS_CIPHER_SM4_GCM_SALT_SIZE    kernelCryptoCipherType = 4
+	// TLS_CIPHER_SM4_GCM_TAG_SIZE     kernelCryptoCipherType = 16
+	// TLS_CIPHER_SM4_GCM_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	// TLS_CIPHER_SM4_CCM              kernelCryptoCipherType = 56
+	// TLS_CIPHER_SM4_CCM_IV_SIZE      kernelCryptoCipherType = 8
+	// TLS_CIPHER_SM4_CCM_KEY_SIZE     kernelCryptoCipherType = 16
+	// TLS_CIPHER_SM4_CCM_SALT_SIZE    kernelCryptoCipherType = 4
+	// TLS_CIPHER_SM4_CCM_TAG_SIZE     kernelCryptoCipherType = 16
+	// TLS_CIPHER_SM4_CCM_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	TLS_CIPHER_ARIA_GCM_128              kernelCryptoCipherType = 57
+	TLS_CIPHER_ARIA_GCM_128_IV_SIZE      kernelCryptoCipherType = 8
+	TLS_CIPHER_ARIA_GCM_128_KEY_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_ARIA_GCM_128_SALT_SIZE    kernelCryptoCipherType = 4
+	TLS_CIPHER_ARIA_GCM_128_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_ARIA_GCM_128_REC_SEQ_SIZE kernelCryptoCipherType = 8
+
+	TLS_CIPHER_ARIA_GCM_256              kernelCryptoCipherType = 58
+	TLS_CIPHER_ARIA_GCM_256_IV_SIZE      kernelCryptoCipherType = 8
+	TLS_CIPHER_ARIA_GCM_256_KEY_SIZE     kernelCryptoCipherType = 32
+	TLS_CIPHER_ARIA_GCM_256_SALT_SIZE    kernelCryptoCipherType = 4
+	TLS_CIPHER_ARIA_GCM_256_TAG_SIZE     kernelCryptoCipherType = 16
+	TLS_CIPHER_ARIA_GCM_256_REC_SEQ_SIZE kernelCryptoCipherType = 8
+)
+
+type kernelCrypto interface {
+	String() string
+}
+
+type kernelCryptoInfo struct {
+	version     uint16
+	cipher_type kernelCryptoCipherType
+}
+
+var _ kernelCrypto = &kernelCryptoAES128GCM{}
+
+type kernelCryptoAES128GCM struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_AES_GCM_128_IV_SIZE]byte
+	key     [TLS_CIPHER_AES_GCM_128_KEY_SIZE]byte
+	salt    [TLS_CIPHER_AES_GCM_128_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoAES128GCM) String() string {
+	crypto.cipher_type = TLS_CIPHER_AES_GCM_128
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+var _ kernelCrypto = &kernelCryptoAES256GCM{}
+
+type kernelCryptoAES256GCM struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_AES_GCM_256_IV_SIZE]byte
+	key     [TLS_CIPHER_AES_GCM_256_KEY_SIZE]byte
+	salt    [TLS_CIPHER_AES_GCM_256_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_AES_GCM_256_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoAES256GCM) String() string {
+	crypto.cipher_type = TLS_CIPHER_AES_GCM_256
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+var _ kernelCrypto = &kernelCryptoAES128CCM{}
+
+type kernelCryptoAES128CCM struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_AES_CCM_128_IV_SIZE]byte
+	key     [TLS_CIPHER_AES_CCM_128_KEY_SIZE]byte
+	salt    [TLS_CIPHER_AES_CCM_128_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoAES128CCM) String() string {
+	crypto.cipher_type = TLS_CIPHER_AES_CCM_128
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+var _ kernelCrypto = &kernelCryptoChacha20Poly1035{}
+
+type kernelCryptoChacha20Poly1035 struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_CHACHA20_POLY1305_IV_SIZE]byte
+	key     [TLS_CIPHER_CHACHA20_POLY1305_KEY_SIZE]byte
+	salt    [TLS_CIPHER_CHACHA20_POLY1305_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_CHACHA20_POLY1305_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoChacha20Poly1035) String() string {
+	crypto.cipher_type = TLS_CIPHER_CHACHA20_POLY1305
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+// var _ kernelCrypto = &kernelCryptoSM4GCM{}
+
+// type kernelCryptoSM4GCM struct {
+// 	kernelCryptoInfo
+// 	iv      [TLS_CIPHER_SM4_GCM_IV_SIZE]byte
+// 	key     [TLS_CIPHER_SM4_GCM_KEY_SIZE]byte
+// 	salt    [TLS_CIPHER_SM4_GCM_SALT_SIZE]byte
+// 	rec_seq [TLS_CIPHER_SM4_GCM_REC_SEQ_SIZE]byte
+// }
+
+// func (crypto *kernelCryptoSM4GCM) String() string {
+// 	crypto.cipher_type = TLS_CIPHER_SM4_GCM
+// 	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+// }
+
+// var _ kernelCrypto = &kernelCryptoSM4CCM{}
+
+// type kernelCryptoSM4CCM struct {
+// 	kernelCryptoInfo
+// 	iv      [TLS_CIPHER_SM4_CCM_IV_SIZE]byte
+// 	key     [TLS_CIPHER_SM4_CCM_KEY_SIZE]byte
+// 	salt    [TLS_CIPHER_SM4_CCM_SALT_SIZE]byte
+// 	rec_seq [TLS_CIPHER_SM4_CCM_REC_SEQ_SIZE]byte
+// }
+
+// func (crypto *kernelCryptoSM4CCM) String() string {
+// 	crypto.cipher_type = TLS_CIPHER_SM4_CCM
+// 	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+// }
+
+var _ kernelCrypto = &kernelCryptoARIA128GCM{}
+
+type kernelCryptoARIA128GCM struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_ARIA_GCM_128_IV_SIZE]byte
+	key     [TLS_CIPHER_ARIA_GCM_128_KEY_SIZE]byte
+	salt    [TLS_CIPHER_ARIA_GCM_128_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_ARIA_GCM_128_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoARIA128GCM) String() string {
+	crypto.cipher_type = TLS_CIPHER_ARIA_GCM_128
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+var _ kernelCrypto = &kernelCryptoARIA256GCM{}
+
+type kernelCryptoARIA256GCM struct {
+	kernelCryptoInfo
+	iv      [TLS_CIPHER_ARIA_GCM_256_IV_SIZE]byte
+	key     [TLS_CIPHER_ARIA_GCM_256_KEY_SIZE]byte
+	salt    [TLS_CIPHER_ARIA_GCM_256_SALT_SIZE]byte
+	rec_seq [TLS_CIPHER_ARIA_GCM_256_REC_SEQ_SIZE]byte
+}
+
+func (crypto *kernelCryptoARIA256GCM) String() string {
+	crypto.cipher_type = TLS_CIPHER_ARIA_GCM_256
+	return string((*[unsafe.Sizeof(*crypto)]byte)(unsafe.Pointer(crypto))[:])
+}
+
+func kernelCipher(kernel *Support, hc *badtls.RawHalfConn, cipherSuite uint16, isRX bool) kernelCrypto {
+	if !kernel.TLS {
+		return nil
+	}
+
+	switch *hc.Version {
+	case tls.VersionTLS12:
+		if isRX && !kernel.TLS_Version13_RX {
+			return nil
+		}
+
+	case tls.VersionTLS13:
+		if !kernel.TLS_Version13 {
+			return nil
+		}
+
+		if isRX && !kernel.TLS_Version13_RX {
+			return nil
+		}
+
+	default:
+		return nil
+	}
+
+	var key, iv []byte
+	if *hc.Version == tls.VersionTLS13 {
+		key, iv = trafficKey(cipherSuiteTLS13ByID(cipherSuite), *hc.TrafficSecret)
+		/*if isRX {
+			key, iv = trafficKey(cipherSuiteTLS13ByID(cipherSuite), keyLog.RemoteTrafficSecret)
+		} else {
+			key, iv = trafficKey(cipherSuiteTLS13ByID(cipherSuite), keyLog.TrafficSecret)
+		}*/
+	} else {
+		// csPtr := cipherSuiteByID(cipherSuite)
+		// keysFromMasterSecret(*hc.Version, csPtr, keyLog.Secret, keyLog.Random)
+		return nil
+	}
+
+	switch cipherSuite {
+	case tls.TLS_AES_128_GCM_SHA256, tls.TLS_RSA_WITH_AES_128_GCM_SHA256, tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
+		crypto := new(kernelCryptoAES128GCM)
+
+		crypto.version = *hc.Version
+		copy(crypto.key[:], key)
+		copy(crypto.iv[:], iv[4:])
+		copy(crypto.salt[:], iv[:4])
+		crypto.rec_seq = *hc.Seq
+
+		return crypto
+	case tls.TLS_AES_256_GCM_SHA384, tls.TLS_RSA_WITH_AES_256_GCM_SHA384, tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
+		if !kernel.TLS_AES_256_GCM {
+			return nil
+		}
+
+		crypto := new(kernelCryptoAES256GCM)
+
+		crypto.version = *hc.Version
+		copy(crypto.key[:], key)
+		copy(crypto.iv[:], iv[4:])
+		copy(crypto.salt[:], iv[:4])
+		crypto.rec_seq = *hc.Seq
+
+		return crypto
+	//case tls.TLS_AES_128_CCM_SHA256, tls.TLS_RSA_WITH_AES_128_CCM_SHA256, tls.TLS_ECDHE_ECDSA_WITH_AES_128_CCM_SHA256:
+	//	if !kernel.TLS_AES_128_CCM {
+	//		return nil
+	//	}
+	//
+	//	crypto := new(kernelCryptoAES128CCM)
+	//
+	//	crypto.version = *hc.Version
+	//	copy(crypto.key[:], key)
+	//	copy(crypto.iv[:], iv[4:])
+	//	copy(crypto.salt[:], iv[:4])
+	//	crypto.rec_seq = *hc.Seq
+	//
+	//	return crypto
+	case tls.TLS_CHACHA20_POLY1305_SHA256, tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256, tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256:
+		if !kernel.TLS_CHACHA20_POLY1305 {
+			return nil
+		}
+
+		crypto := new(kernelCryptoChacha20Poly1035)
+
+		crypto.version = *hc.Version
+		copy(crypto.key[:], key)
+		copy(crypto.iv[:], iv)
+		crypto.rec_seq = *hc.Seq
+
+		return crypto
+	//case tls.TLS_RSA_WITH_ARIA_128_GCM_SHA256, tls.TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256, tls.TLS_ECDHE_ECDSA_WITH_ARIA_128_GCM_SHA256:
+	//	if !kernel.TLS_ARIA_GCM {
+	//		return nil
+	//	}
+	//
+	//	crypto := new(kernelCryptoARIA128GCM)
+	//
+	//	crypto.version = *hc.Version
+	//	copy(crypto.key[:], key)
+	//	copy(crypto.iv[:], iv[4:])
+	//	copy(crypto.salt[:], iv[:4])
+	//	crypto.rec_seq = *hc.Seq
+	//
+	//	return crypto
+	//case tls.TLS_RSA_WITH_ARIA_256_GCM_SHA384, tls.TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384, tls.TLS_ECDHE_ECDSA_WITH_ARIA_256_GCM_SHA384:
+	//	if !kernel.TLS_ARIA_GCM {
+	//		return nil
+	//	}
+	//
+	//	crypto := new(kernelCryptoARIA256GCM)
+	//
+	//	crypto.version = *hc.Version
+	//	copy(crypto.key[:], key)
+	//	copy(crypto.iv[:], iv[4:])
+	//	copy(crypto.salt[:], iv[:4])
+	//	crypto.rec_seq = *hc.Seq
+	//
+	//	return crypto
+	default:
+		return nil
+	}
+}

common/ktls/ktls_close.go

@@ -0,0 +1,67 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"fmt"
+	"net"
+	"time"
+)
+
+func (c *Conn) Close() error {
+	if !c.kernelTx {
+		return c.Conn.Close()
+	}
+
+	// Interlock with Conn.Write above.
+	var x int32
+	for {
+		x = c.rawConn.ActiveCall.Load()
+		if x&1 != 0 {
+			return net.ErrClosed
+		}
+		if c.rawConn.ActiveCall.CompareAndSwap(x, x|1) {
+			break
+		}
+	}
+	if x != 0 {
+		// io.Writer and io.Closer should not be used concurrently.
+		// If Close is called while a Write is currently in-flight,
+		// interpret that as a sign that this Close is really just
+		// being used to break the Write and/or clean up resources and
+		// avoid sending the alertCloseNotify, which may block
+		// waiting on handshakeMutex or the c.out mutex.
+		return c.conn.Close()
+	}
+
+	var alertErr error
+	if c.rawConn.IsHandshakeComplete.Load() {
+		if err := c.closeNotify(); err != nil {
+			alertErr = fmt.Errorf("tls: failed to send closeNotify alert (but connection was closed anyway): %w", err)
+		}
+	}
+
+	if err := c.conn.Close(); err != nil {
+		return err
+	}
+	return alertErr
+}
+
+func (c *Conn) closeNotify() error {
+	c.rawConn.Out.Lock()
+	defer c.rawConn.Out.Unlock()
+
+	if !*c.rawConn.CloseNotifySent {
+		// Set a Write Deadline to prevent possibly blocking forever.
+		c.SetWriteDeadline(time.Now().Add(time.Second * 5))
+		*c.rawConn.CloseNotifyErr = c.sendAlertLocked(alertCloseNotify)
+		*c.rawConn.CloseNotifySent = true
+		// Any subsequent writes will fail.
+		c.SetWriteDeadline(time.Now())
+	}
+	return *c.rawConn.CloseNotifyErr
+}

common/ktls/ktls_const.go

@@ -0,0 +1,24 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+const (
+	maxPlaintext               = 16384        // maximum plaintext payload length
+	maxCiphertext              = 16384 + 2048 // maximum ciphertext payload length
+	maxCiphertextTLS13         = 16384 + 256  // maximum ciphertext length in TLS 1.3
+	recordHeaderLen            = 5            // record header length
+	maxHandshake               = 65536        // maximum handshake we support (protocol max is 16 MB)
+	maxHandshakeCertificateMsg = 262144       // maximum certificate message size (256 KiB)
+	maxUselessRecords          = 16           // maximum number of consecutive non-advancing records
+)
+
+const (
+	recordTypeChangeCipherSpec = 20
+	recordTypeAlert            = 21
+	recordTypeHandshake        = 22
+	recordTypeApplicationData  = 23
+)

common/ktls/ktls_handshake_messages.go

@@ -0,0 +1,238 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"fmt"
+
+	"golang.org/x/crypto/cryptobyte"
+)
+
+// The marshalingFunction type is an adapter to allow the use of ordinary
+// functions as cryptobyte.MarshalingValue.
+type marshalingFunction func(b *cryptobyte.Builder) error
+
+func (f marshalingFunction) Marshal(b *cryptobyte.Builder) error {
+	return f(b)
+}
+
+// addBytesWithLength appends a sequence of bytes to the cryptobyte.Builder. If
+// the length of the sequence is not the value specified, it produces an error.
+func addBytesWithLength(b *cryptobyte.Builder, v []byte, n int) {
+	b.AddValue(marshalingFunction(func(b *cryptobyte.Builder) error {
+		if len(v) != n {
+			return fmt.Errorf("invalid value length: expected %d, got %d", n, len(v))
+		}
+		b.AddBytes(v)
+		return nil
+	}))
+}
+
+// addUint64 appends a big-endian, 64-bit value to the cryptobyte.Builder.
+func addUint64(b *cryptobyte.Builder, v uint64) {
+	b.AddUint32(uint32(v >> 32))
+	b.AddUint32(uint32(v))
+}
+
+// readUint64 decodes a big-endian, 64-bit value into out and advances over it.
+// It reports whether the read was successful.
+func readUint64(s *cryptobyte.String, out *uint64) bool {
+	var hi, lo uint32
+	if !s.ReadUint32(&hi) || !s.ReadUint32(&lo) {
+		return false
+	}
+	*out = uint64(hi)<<32 | uint64(lo)
+	return true
+}
+
+// readUint8LengthPrefixed acts like s.ReadUint8LengthPrefixed, but targets a
+// []byte instead of a cryptobyte.String.
+func readUint8LengthPrefixed(s *cryptobyte.String, out *[]byte) bool {
+	return s.ReadUint8LengthPrefixed((*cryptobyte.String)(out))
+}
+
+// readUint16LengthPrefixed acts like s.ReadUint16LengthPrefixed, but targets a
+// []byte instead of a cryptobyte.String.
+func readUint16LengthPrefixed(s *cryptobyte.String, out *[]byte) bool {
+	return s.ReadUint16LengthPrefixed((*cryptobyte.String)(out))
+}
+
+// readUint24LengthPrefixed acts like s.ReadUint24LengthPrefixed, but targets a
+// []byte instead of a cryptobyte.String.
+func readUint24LengthPrefixed(s *cryptobyte.String, out *[]byte) bool {
+	return s.ReadUint24LengthPrefixed((*cryptobyte.String)(out))
+}
+
+type keyUpdateMsg struct {
+	updateRequested bool
+}
+
+func (m *keyUpdateMsg) marshal() ([]byte, error) {
+	var b cryptobyte.Builder
+	b.AddUint8(typeKeyUpdate)
+	b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
+		if m.updateRequested {
+			b.AddUint8(1)
+		} else {
+			b.AddUint8(0)
+		}
+	})
+
+	return b.Bytes()
+}
+
+func (m *keyUpdateMsg) unmarshal(data []byte) bool {
+	s := cryptobyte.String(data)
+
+	var updateRequested uint8
+	if !s.Skip(4) || // message type and uint24 length field
+		!s.ReadUint8(&updateRequested) || !s.Empty() {
+		return false
+	}
+	switch updateRequested {
+	case 0:
+		m.updateRequested = false
+	case 1:
+		m.updateRequested = true
+	default:
+		return false
+	}
+	return true
+}
+
+// TLS handshake message types.
+const (
+	typeHelloRequest          uint8 = 0
+	typeClientHello           uint8 = 1
+	typeServerHello           uint8 = 2
+	typeNewSessionTicket      uint8 = 4
+	typeEndOfEarlyData        uint8 = 5
+	typeEncryptedExtensions   uint8 = 8
+	typeCertificate           uint8 = 11
+	typeServerKeyExchange     uint8 = 12
+	typeCertificateRequest    uint8 = 13
+	typeServerHelloDone       uint8 = 14
+	typeCertificateVerify     uint8 = 15
+	typeClientKeyExchange     uint8 = 16
+	typeFinished              uint8 = 20
+	typeCertificateStatus     uint8 = 22
+	typeKeyUpdate             uint8 = 24
+	typeCompressedCertificate uint8 = 25
+	typeMessageHash           uint8 = 254 // synthetic message
+)
+
+// TLS compression types.
+const (
+	compressionNone uint8 = 0
+)
+
+// TLS extension numbers
+const (
+	extensionServerName              uint16 = 0
+	extensionStatusRequest           uint16 = 5
+	extensionSupportedCurves         uint16 = 10 // supported_groups in TLS 1.3, see RFC 8446, Section 4.2.7
+	extensionSupportedPoints         uint16 = 11
+	extensionSignatureAlgorithms     uint16 = 13
+	extensionALPN                    uint16 = 16
+	extensionSCT                     uint16 = 18
+	extensionPadding                 uint16 = 21
+	extensionExtendedMasterSecret    uint16 = 23
+	extensionCompressCertificate     uint16 = 27 // compress_certificate in TLS 1.3
+	extensionSessionTicket           uint16 = 35
+	extensionPreSharedKey            uint16 = 41
+	extensionEarlyData               uint16 = 42
+	extensionSupportedVersions       uint16 = 43
+	extensionCookie                  uint16 = 44
+	extensionPSKModes                uint16 = 45
+	extensionCertificateAuthorities  uint16 = 47
+	extensionSignatureAlgorithmsCert uint16 = 50
+	extensionKeyShare                uint16 = 51
+	extensionQUICTransportParameters uint16 = 57
+	extensionALPS                    uint16 = 17513
+	extensionRenegotiationInfo       uint16 = 0xff01
+	extensionECHOuterExtensions      uint16 = 0xfd00
+	extensionEncryptedClientHello    uint16 = 0xfe0d
+)
+
+type handshakeMessage interface {
+	marshal() ([]byte, error)
+	unmarshal([]byte) bool
+}
+type newSessionTicketMsgTLS13 struct {
+	lifetime     uint32
+	ageAdd       uint32
+	nonce        []byte
+	label        []byte
+	maxEarlyData uint32
+}
+
+func (m *newSessionTicketMsgTLS13) marshal() ([]byte, error) {
+	var b cryptobyte.Builder
+	b.AddUint8(typeNewSessionTicket)
+	b.AddUint24LengthPrefixed(func(b *cryptobyte.Builder) {
+		b.AddUint32(m.lifetime)
+		b.AddUint32(m.ageAdd)
+		b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
+			b.AddBytes(m.nonce)
+		})
+		b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
+			b.AddBytes(m.label)
+		})
+
+		b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
+			if m.maxEarlyData > 0 {
+				b.AddUint16(extensionEarlyData)
+				b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
+					b.AddUint32(m.maxEarlyData)
+				})
+			}
+		})
+	})
+
+	return b.Bytes()
+}
+
+func (m *newSessionTicketMsgTLS13) unmarshal(data []byte) bool {
+	*m = newSessionTicketMsgTLS13{}
+	s := cryptobyte.String(data)
+
+	var extensions cryptobyte.String
+	if !s.Skip(4) || // message type and uint24 length field
+		!s.ReadUint32(&m.lifetime) ||
+		!s.ReadUint32(&m.ageAdd) ||
+		!readUint8LengthPrefixed(&s, &m.nonce) ||
+		!readUint16LengthPrefixed(&s, &m.label) ||
+		!s.ReadUint16LengthPrefixed(&extensions) ||
+		!s.Empty() {
+		return false
+	}
+
+	for !extensions.Empty() {
+		var extension uint16
+		var extData cryptobyte.String
+		if !extensions.ReadUint16(&extension) ||
+			!extensions.ReadUint16LengthPrefixed(&extData) {
+			return false
+		}
+
+		switch extension {
+		case extensionEarlyData:
+			if !extData.ReadUint32(&m.maxEarlyData) {
+				return false
+			}
+		default:
+			// Ignore unknown extensions.
+			continue
+		}
+
+		if !extData.Empty() {
+			return false
+		}
+	}
+
+	return true
+}

common/ktls/ktls_key_update.go

@@ -0,0 +1,173 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+)
+
+// handlePostHandshakeMessage processes a handshake message arrived after the
+// handshake is complete. Up to TLS 1.2, it indicates the start of a renegotiation.
+func (c *Conn) handlePostHandshakeMessage() error {
+	if *c.rawConn.Vers != tls.VersionTLS13 {
+		return errors.New("ktls: kernel does not support TLS 1.2 renegotiation")
+	}
+
+	msg, err := c.readHandshake(nil)
+	if err != nil {
+		return err
+	}
+	//c.retryCount++
+	//if c.retryCount > maxUselessRecords {
+	//	c.sendAlert(alertUnexpectedMessage)
+	//	return c.in.setErrorLocked(errors.New("tls: too many non-advancing records"))
+	//}
+
+	switch msg := msg.(type) {
+	case *newSessionTicketMsgTLS13:
+		// return errors.New("ktls: received new session ticket")
+		return nil
+	case *keyUpdateMsg:
+		return c.handleKeyUpdate(msg)
+	}
+	// The QUIC layer is supposed to treat an unexpected post-handshake CertificateRequest
+	// as a QUIC-level PROTOCOL_VIOLATION error (RFC 9001, Section 4.4). Returning an
+	// unexpected_message alert here doesn't provide it with enough information to distinguish
+	// this condition from other unexpected messages. This is probably fine.
+	c.sendAlert(alertUnexpectedMessage)
+	return fmt.Errorf("tls: received unexpected handshake message of type %T", msg)
+}
+
+func (c *Conn) handleKeyUpdate(keyUpdate *keyUpdateMsg) error {
+	//if c.quic != nil {
+	//	c.sendAlert(alertUnexpectedMessage)
+	//	return c.in.setErrorLocked(errors.New("tls: received unexpected key update message"))
+	//}
+
+	cipherSuite := cipherSuiteTLS13ByID(*c.rawConn.CipherSuite)
+	if cipherSuite == nil {
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertInternalError))
+	}
+
+	newSecret := nextTrafficSecret(cipherSuite, *c.rawConn.In.TrafficSecret)
+	c.rawConn.In.SetTrafficSecret(cipherSuite, 0 /*tls.QUICEncryptionLevelInitial*/, newSecret)
+
+	err := c.resetupRX()
+	if err != nil {
+		c.sendAlert(alertInternalError)
+		return c.rawConn.In.SetErrorLocked(fmt.Errorf("ktls: resetupRX failed: %w", err))
+	}
+
+	if keyUpdate.updateRequested {
+		c.rawConn.Out.Lock()
+		defer c.rawConn.Out.Unlock()
+
+		resetup, err := c.resetupTX()
+		if err != nil {
+			c.sendAlertLocked(alertInternalError)
+			return c.rawConn.Out.SetErrorLocked(fmt.Errorf("ktls: resetupTX failed: %w", err))
+		}
+
+		msg := &keyUpdateMsg{}
+		msgBytes, err := msg.marshal()
+		if err != nil {
+			return err
+		}
+		_, err = c.writeRecordLocked(recordTypeHandshake, msgBytes)
+		if err != nil {
+			// Surface the error at the next write.
+			c.rawConn.Out.SetErrorLocked(err)
+			return nil
+		}
+
+		newSecret := nextTrafficSecret(cipherSuite, *c.rawConn.Out.TrafficSecret)
+		c.rawConn.Out.SetTrafficSecret(cipherSuite, 0 /*QUICEncryptionLevelInitial*/, newSecret)
+
+		err = resetup()
+		if err != nil {
+			return c.rawConn.Out.SetErrorLocked(fmt.Errorf("ktls: resetupTX failed: %w", err))
+		}
+	}
+
+	return nil
+}
+
+func (c *Conn) readHandshakeBytes(n int) error {
+	//if c.quic != nil {
+	//	return c.quicReadHandshakeBytes(n)
+	//}
+	for c.rawConn.Hand.Len() < n {
+		if err := c.readRecord(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (c *Conn) readHandshake(transcript io.Writer) (any, error) {
+	if err := c.readHandshakeBytes(4); err != nil {
+		return nil, err
+	}
+	data := c.rawConn.Hand.Bytes()
+
+	maxHandshakeSize := maxHandshake
+	// hasVers indicates we're past the first message, forcing someone trying to
+	// make us just allocate a large buffer to at least do the initial part of
+	// the handshake first.
+	//if c.haveVers && data[0] == typeCertificate {
+	// Since certificate messages are likely to be the only messages that
+	// can be larger than maxHandshake, we use a special limit for just
+	// those messages.
+	//maxHandshakeSize = maxHandshakeCertificateMsg
+	//}
+
+	n := int(data[1])<<16 | int(data[2])<<8 | int(data[3])
+	if n > maxHandshakeSize {
+		c.sendAlertLocked(alertInternalError)
+		return nil, c.rawConn.In.SetErrorLocked(fmt.Errorf("tls: handshake message of length %d bytes exceeds maximum of %d bytes", n, maxHandshakeSize))
+	}
+	if err := c.readHandshakeBytes(4 + n); err != nil {
+		return nil, err
+	}
+	data = c.rawConn.Hand.Next(4 + n)
+	return c.unmarshalHandshakeMessage(data, transcript)
+}
+
+func (c *Conn) unmarshalHandshakeMessage(data []byte, transcript io.Writer) (any, error) {
+	var m handshakeMessage
+	switch data[0] {
+	case typeNewSessionTicket:
+		if *c.rawConn.Vers == tls.VersionTLS13 {
+			m = new(newSessionTicketMsgTLS13)
+		} else {
+			return nil, os.ErrInvalid
+		}
+	case typeKeyUpdate:
+		m = new(keyUpdateMsg)
+	default:
+		return nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+	}
+
+	// The handshake message unmarshalers
+	// expect to be able to keep references to data,
+	// so pass in a fresh copy that won't be overwritten.
+	data = append([]byte(nil), data...)
+
+	if !m.unmarshal(data) {
+		return nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertDecodeError))
+	}
+
+	if transcript != nil {
+		transcript.Write(data)
+	}
+
+	return m, nil
+}

common/ktls/ktls_linux.go

@@ -0,0 +1,311 @@
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/tls"
+	"errors"
+	"io"
+	"os"
+	"strings"
+	"sync"
+	"syscall"
+	"unsafe"
+
+	"github.com/sagernet/sing/common/control"
+	E "github.com/sagernet/sing/common/exceptions"
+
+	"github.com/blang/semver/v4"
+	"golang.org/x/sys/unix"
+)
+
+// mod from https://gitlab.com/go-extension/tls
+
+const (
+	TLS_TX               = 1
+	TLS_RX               = 2
+	TLS_TX_ZEROCOPY_RO   = 3 // TX zerocopy (only sendfile now)
+	TLS_RX_EXPECT_NO_PAD = 4 // Attempt opportunistic zero-copy, TLS 1.3 only
+
+	TLS_SET_RECORD_TYPE = 1
+	TLS_GET_RECORD_TYPE = 2
+)
+
+type Support struct {
+	TLS, TLS_RX                     bool
+	TLS_Version13, TLS_Version13_RX bool
+
+	TLS_TX_ZEROCOPY  bool
+	TLS_RX_NOPADDING bool
+
+	TLS_AES_256_GCM       bool
+	TLS_AES_128_CCM       bool
+	TLS_CHACHA20_POLY1305 bool
+	TLS_SM4               bool
+	TLS_ARIA_GCM          bool
+
+	TLS_Version13_KeyUpdate bool
+}
+
+var KernelSupport = sync.OnceValues(func() (*Support, error) {
+	_, err := os.Stat("/sys/module/tls")
+	if err != nil {
+		return nil, E.New("ktls: kernel module tls not found")
+	}
+
+	var uname unix.Utsname
+	err = unix.Uname(&uname)
+	if err != nil {
+		return nil, err
+	}
+
+	kernelVersion, err := semver.Parse(strings.Trim(string(uname.Release[:]), "\x00"))
+	if err != nil {
+		return nil, err
+	}
+	kernelVersion.Pre = nil
+	kernelVersion.Build = nil
+
+	var support Support
+
+	switch {
+	case kernelVersion.GTE(semver.Version{Major: 6, Minor: 14}):
+		support.TLS_Version13_KeyUpdate = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 6, Minor: 1}):
+		support.TLS_ARIA_GCM = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 6}):
+		support.TLS_Version13_RX = true
+		support.TLS_RX_NOPADDING = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 5, Minor: 19}):
+		support.TLS_TX_ZEROCOPY = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 5, Minor: 16}):
+		support.TLS_SM4 = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 5, Minor: 11}):
+		support.TLS_CHACHA20_POLY1305 = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 5, Minor: 2}):
+		support.TLS_AES_128_CCM = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 5, Minor: 1}):
+		support.TLS_AES_256_GCM = true
+		support.TLS_Version13 = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 4, Minor: 17}):
+		support.TLS_RX = true
+		fallthrough
+	case kernelVersion.GTE(semver.Version{Major: 4, Minor: 13}):
+		support.TLS = true
+	}
+
+	return &support, nil
+})
+
+func (c *Conn) setupKernel(txOffload, rxOffload bool) error {
+	if !txOffload && !rxOffload {
+		return nil
+	}
+	support, err := KernelSupport()
+	if err != nil {
+		return err
+	}
+	if !support.TLS {
+		return nil
+	}
+	c.rawConn.Out.Lock()
+	defer c.rawConn.Out.Unlock()
+	err = control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+		return syscall.SetsockoptString(int(fd), unix.SOL_TCP, unix.TCP_ULP, "tls")
+	})
+	if err != nil {
+		return E.Cause(err, "initialize kernel TLS")
+	}
+
+	if rxOffload {
+		rxCrypto := kernelCipher(support, c.rawConn.In, *c.rawConn.CipherSuite, true)
+		if rxCrypto == nil {
+			return E.New("kTLS: unsupported cipher suite")
+		}
+		err = control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+			return syscall.SetsockoptString(int(fd), unix.SOL_TLS, TLS_RX, rxCrypto.String())
+		})
+		if err != nil {
+			return err
+		}
+		if /*config.KernelRXExpectNoPad &&*/ *c.rawConn.Vers >= tls.VersionTLS13 && support.TLS_RX_NOPADDING {
+			err = control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+				return syscall.SetsockoptInt(int(fd), unix.SOL_TLS, TLS_RX_EXPECT_NO_PAD, 1)
+			})
+			if err != nil {
+				return err
+			}
+		}
+		c.kernelRx = true
+	}
+
+	if txOffload {
+		txCrypto := kernelCipher(support, c.rawConn.Out, *c.rawConn.CipherSuite, false)
+		if txCrypto == nil {
+			return E.New("kTLS: unsupported cipher suite")
+		}
+		err = control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+			return syscall.SetsockoptString(int(fd), unix.SOL_TLS, TLS_TX, txCrypto.String())
+		})
+		if err != nil {
+			return err
+		}
+		if support.TLS_TX_ZEROCOPY {
+			err = control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+				return syscall.SetsockoptInt(int(fd), unix.SOL_TLS, TLS_TX_ZEROCOPY_RO, 1)
+			})
+			if err != nil {
+				return err
+			}
+		}
+		c.kernelTx = true
+	}
+
+	return nil
+}
+
+func (c *Conn) resetupTX() (func() error, error) {
+	if !c.kernelTx {
+		return nil, nil
+	}
+	support, err := KernelSupport()
+	if err != nil {
+		return nil, err
+	}
+	if !support.TLS_Version13_KeyUpdate {
+		return nil, errors.New("ktls: kernel does not support rekey")
+	}
+	txCrypto := kernelCipher(support, c.rawConn.Out, *c.rawConn.CipherSuite, false)
+	if txCrypto == nil {
+		return nil, errors.New("ktls: set kernelCipher on unsupported tls session")
+	}
+	return func() error {
+		return control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+			return syscall.SetsockoptString(int(fd), unix.SOL_TLS, TLS_TX, txCrypto.String())
+		})
+	}, nil
+}
+
+func (c *Conn) resetupRX() error {
+	if !c.kernelRx {
+		return nil
+	}
+	support, err := KernelSupport()
+	if err != nil {
+		return err
+	}
+	if !support.TLS_Version13_KeyUpdate {
+		return errors.New("ktls: kernel does not support rekey")
+	}
+	rxCrypto := kernelCipher(support, c.rawConn.In, *c.rawConn.CipherSuite, true)
+	if rxCrypto == nil {
+		return errors.New("ktls: set kernelCipher on unsupported tls session")
+	}
+	return control.Raw(c.rawSyscallConn, func(fd uintptr) error {
+		return syscall.SetsockoptString(int(fd), unix.SOL_TLS, TLS_RX, rxCrypto.String())
+	})
+}
+
+func (c *Conn) readKernelRecord() (uint8, []byte, error) {
+	if c.rawConn.RawInput.Len() < maxPlaintext {
+		c.rawConn.RawInput.Grow(maxPlaintext - c.rawConn.RawInput.Len())
+	}
+
+	data := c.rawConn.RawInput.Bytes()[:maxPlaintext]
+
+	// cmsg for record type
+	buffer := make([]byte, unix.CmsgSpace(1))
+	cmsg := (*unix.Cmsghdr)(unsafe.Pointer(&buffer[0]))
+	cmsg.SetLen(unix.CmsgLen(1))
+
+	var iov unix.Iovec
+	iov.Base = &data[0]
+	iov.SetLen(len(data))
+
+	var msg unix.Msghdr
+	msg.Control = &buffer[0]
+	msg.Controllen = cmsg.Len
+	msg.Iov = &iov
+	msg.Iovlen = 1
+
+	var n int
+	var err error
+	er := c.rawSyscallConn.Read(func(fd uintptr) bool {
+		n, err = recvmsg(int(fd), &msg, 0)
+		return err != unix.EAGAIN
+	})
+	if er != nil {
+		return 0, nil, er
+	}
+	switch err {
+	case nil:
+	case syscall.EINVAL:
+		return 0, nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertProtocolVersion))
+	case syscall.EMSGSIZE:
+		return 0, nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertRecordOverflow))
+	case syscall.EBADMSG:
+		return 0, nil, c.rawConn.In.SetErrorLocked(c.sendAlert(alertDecryptError))
+	default:
+		return 0, nil, err
+	}
+
+	if n <= 0 {
+		return 0, nil, io.EOF
+	}
+
+	if cmsg.Level == unix.SOL_TLS && cmsg.Type == TLS_GET_RECORD_TYPE {
+		typ := buffer[unix.CmsgLen(0)]
+		return typ, data[:n], nil
+	}
+
+	return recordTypeApplicationData, data[:n], nil
+}
+
+func (c *Conn) writeKernelRecord(typ uint16, data []byte) (int, error) {
+	if typ == recordTypeApplicationData {
+		return c.conn.Write(data)
+	}
+
+	// cmsg for record type
+	buffer := make([]byte, unix.CmsgSpace(1))
+	cmsg := (*unix.Cmsghdr)(unsafe.Pointer(&buffer[0]))
+	cmsg.SetLen(unix.CmsgLen(1))
+	buffer[unix.CmsgLen(0)] = byte(typ)
+	cmsg.Level = unix.SOL_TLS
+	cmsg.Type = TLS_SET_RECORD_TYPE
+
+	var iov unix.Iovec
+	iov.Base = &data[0]
+	iov.SetLen(len(data))
+
+	var msg unix.Msghdr
+	msg.Control = &buffer[0]
+	msg.Controllen = cmsg.Len
+	msg.Iov = &iov
+	msg.Iovlen = 1
+
+	var n int
+	var err error
+	ew := c.rawSyscallConn.Write(func(fd uintptr) bool {
+		n, err = sendmsg(int(fd), &msg, 0)
+		return err != unix.EAGAIN
+	})
+	if ew != nil {
+		return 0, ew
+	}
+	return n, err
+}
+
+//go:linkname recvmsg golang.org/x/sys/unix.recvmsg
+func recvmsg(fd int, msg *unix.Msghdr, flags int) (n int, err error)
+
+//go:linkname sendmsg golang.org/x/sys/unix.sendmsg
+func sendmsg(fd int, msg *unix.Msghdr, flags int) (n int, err error)

common/ktls/ktls_prf.go

@@ -0,0 +1,24 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import "unsafe"
+
+//go:linkname cipherSuiteByID github.com/metacubex/utls.cipherSuiteByID
+func cipherSuiteByID(id uint16) unsafe.Pointer
+
+//go:linkname keysFromMasterSecret github.com/metacubex/utls.keysFromMasterSecret
+func keysFromMasterSecret(version uint16, suite unsafe.Pointer, masterSecret, clientRandom, serverRandom []byte, macLen, keyLen, ivLen int) (clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV []byte)
+
+//go:linkname cipherSuiteTLS13ByID github.com/metacubex/utls.cipherSuiteTLS13ByID
+func cipherSuiteTLS13ByID(id uint16) unsafe.Pointer
+
+//go:linkname nextTrafficSecret github.com/metacubex/utls.(*cipherSuiteTLS13).nextTrafficSecret
+func nextTrafficSecret(cs unsafe.Pointer, trafficSecret []byte) []byte
+
+//go:linkname trafficKey github.com/metacubex/utls.(*cipherSuiteTLS13).trafficKey
+func trafficKey(cs unsafe.Pointer, trafficSecret []byte) (key, iv []byte)

common/ktls/ktls_read.go

@@ -0,0 +1,292 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"bytes"
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net"
+)
+
+func (c *Conn) Read(b []byte) (int, error) {
+	if !c.kernelRx {
+		return c.Conn.Read(b)
+	}
+
+	if len(b) == 0 {
+		// Put this after Handshake, in case people were calling
+		// Read(nil) for the side effect of the Handshake.
+		return 0, nil
+	}
+
+	c.rawConn.In.Lock()
+	defer c.rawConn.In.Unlock()
+
+	for c.rawConn.Input.Len() == 0 {
+		if err := c.readRecord(); err != nil {
+			return 0, err
+		}
+		for c.rawConn.Hand.Len() > 0 {
+			if err := c.handlePostHandshakeMessage(); err != nil {
+				return 0, err
+			}
+		}
+	}
+
+	n, _ := c.rawConn.Input.Read(b)
+
+	// If a close-notify alert is waiting, read it so that we can return (n,
+	// EOF) instead of (n, nil), to signal to the HTTP response reading
+	// goroutine that the connection is now closed. This eliminates a race
+	// where the HTTP response reading goroutine would otherwise not observe
+	// the EOF until its next read, by which time a client goroutine might
+	// have already tried to reuse the HTTP connection for a new request.
+	// See https://golang.org/cl/76400046 and https://golang.org/issue/3514
+	if n != 0 && c.rawConn.Input.Len() == 0 && c.rawConn.RawInput.Len() > 0 &&
+		c.rawConn.RawInput.Bytes()[0] == recordTypeAlert {
+		if err := c.readRecord(); err != nil {
+			return n, err // will be io.EOF on closeNotify
+		}
+	}
+
+	return n, nil
+}
+
+func (c *Conn) readRecord() error {
+	if *c.rawConn.In.Err != nil {
+		return *c.rawConn.In.Err
+	}
+
+	typ, data, err := c.readRawRecord()
+	if err != nil {
+		return err
+	}
+
+	if len(data) > maxPlaintext {
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertRecordOverflow))
+	}
+
+	// Application Data messages are always protected.
+	if c.rawConn.In.Cipher == nil && typ == recordTypeApplicationData {
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+	}
+
+	//if typ != recordTypeAlert && typ != recordTypeChangeCipherSpec && len(data) > 0 {
+	// This is a state-advancing message: reset the retry count.
+	// c.retryCount = 0
+	//}
+
+	// Handshake messages MUST NOT be interleaved with other record types in TLS 1.3.
+	if *c.rawConn.Vers == tls.VersionTLS13 && typ != recordTypeHandshake && c.rawConn.Hand.Len() > 0 {
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+	}
+
+	switch typ {
+	default:
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+	case recordTypeAlert:
+		//if c.quic != nil {
+		//	return c.rawConn.In.setErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		//}
+		if len(data) != 2 {
+			return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		}
+		if data[1] == alertCloseNotify {
+			return c.rawConn.In.SetErrorLocked(io.EOF)
+		}
+		if *c.rawConn.Vers == tls.VersionTLS13 {
+			// TLS 1.3 removed warning-level alerts except for alertUserCanceled
+			// (RFC 8446, § 6.1). Since at least one major implementation
+			// (https://bugs.openjdk.org/browse/JDK-8323517) misuses this alert,
+			// many TLS stacks now ignore it outright when seen in a TLS 1.3
+			// handshake (e.g. BoringSSL, NSS, Rustls).
+			if data[1] == alertUserCanceled {
+				// Like TLS 1.2 alertLevelWarning alerts, we drop the record and retry.
+				return c.retryReadRecord( /*expectChangeCipherSpec*/ )
+			}
+			return c.rawConn.In.SetErrorLocked(&net.OpError{Op: "remote error", Err: tls.AlertError(data[1])})
+		}
+		switch data[0] {
+		case alertLevelWarning:
+			// Drop the record on the floor and retry.
+			return c.retryReadRecord( /*expectChangeCipherSpec*/ )
+		case alertLevelError:
+			return c.rawConn.In.SetErrorLocked(&net.OpError{Op: "remote error", Err: tls.AlertError(data[1])})
+		default:
+			return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		}
+
+	case recordTypeChangeCipherSpec:
+		if len(data) != 1 || data[0] != 1 {
+			return c.rawConn.In.SetErrorLocked(c.sendAlert(alertDecodeError))
+		}
+		// Handshake messages are not allowed to fragment across the CCS.
+		if c.rawConn.Hand.Len() > 0 {
+			return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		}
+		// In TLS 1.3, change_cipher_spec records are ignored until the
+		// Finished. See RFC 8446, Appendix D.4. Note that according to Section
+		// 5, a server can send a ChangeCipherSpec before its ServerHello, when
+		// c.vers is still unset. That's not useful though and suspicious if the
+		// server then selects a lower protocol version, so don't allow that.
+		if *c.rawConn.Vers == tls.VersionTLS13 {
+			return c.retryReadRecord( /*expectChangeCipherSpec*/ )
+		}
+		// if !expectChangeCipherSpec {
+		return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		//}
+		//if err := c.rawConn.In.changeCipherSpec(); err != nil {
+		//	return c.rawConn.In.setErrorLocked(c.sendAlert(err.(alert)))
+		//}
+
+	case recordTypeApplicationData:
+		// Some OpenSSL servers send empty records in order to randomize the
+		// CBC RawIV. Ignore a limited number of empty records.
+		if len(data) == 0 {
+			return c.retryReadRecord( /*expectChangeCipherSpec*/ )
+		}
+		// Note that data is owned by c.rawInput, following the Next call above,
+		// to avoid copying the plaintext. This is safe because c.rawInput is
+		// not read from or written to until c.input is drained.
+		c.rawConn.Input.Reset(data)
+	case recordTypeHandshake:
+		if len(data) == 0 {
+			return c.rawConn.In.SetErrorLocked(c.sendAlert(alertUnexpectedMessage))
+		}
+		c.rawConn.Hand.Write(data)
+	}
+
+	return nil
+}
+
+//nolint:staticcheck
+func (c *Conn) readRawRecord() (typ uint8, data []byte, err error) {
+	// Read from kernel.
+	if c.kernelRx {
+		return c.readKernelRecord()
+	}
+
+	// Read header, payload.
+	if err = c.readFromUntil(c.conn, recordHeaderLen); err != nil {
+		// RFC 8446, Section 6.1 suggests that EOF without an alertCloseNotify
+		// is an error, but popular web sites seem to do this, so we accept it
+		// if and only if at the record boundary.
+		if err == io.ErrUnexpectedEOF && c.rawConn.RawInput.Len() == 0 {
+			err = io.EOF
+		}
+		if e, ok := err.(net.Error); !ok || !e.Temporary() {
+			c.rawConn.In.SetErrorLocked(err)
+		}
+		return
+	}
+	hdr := c.rawConn.RawInput.Bytes()[:recordHeaderLen]
+	typ = hdr[0]
+
+	vers := uint16(hdr[1])<<8 | uint16(hdr[2])
+	expectedVers := *c.rawConn.Vers
+	if expectedVers == tls.VersionTLS13 {
+		// All TLS 1.3 records are expected to have 0x0303 (1.2) after
+		// the initial hello (RFC 8446 Section 5.1).
+		expectedVers = tls.VersionTLS12
+	}
+	n := int(hdr[3])<<8 | int(hdr[4])
+	if /*c.haveVers && */ vers != expectedVers {
+		c.sendAlert(alertProtocolVersion)
+		msg := fmt.Sprintf("received record with version %x when expecting version %x", vers, expectedVers)
+		err = c.rawConn.In.SetErrorLocked(c.newRecordHeaderError(nil, msg))
+		return
+	}
+	//if !c.haveVers {
+	//	// First message, be extra suspicious: this might not be a TLS
+	//	// client. Bail out before reading a full 'body', if possible.
+	//	// The current max version is 3.3 so if the version is >= 16.0,
+	//	// it's probably not real.
+	//	if (typ != recordTypeAlert && typ != recordTypeHandshake) || vers >= 0x1000 {
+	//		err = c.rawConn.In.SetErrorLocked(c.newRecordHeaderError(c.conn, "first record does not look like a TLS handshake"))
+	//		return
+	//	}
+	//}
+	if *c.rawConn.Vers == tls.VersionTLS13 && n > maxCiphertextTLS13 || n > maxCiphertext {
+		c.sendAlert(alertRecordOverflow)
+		msg := fmt.Sprintf("oversized record received with length %d", n)
+		err = c.rawConn.In.SetErrorLocked(c.newRecordHeaderError(nil, msg))
+		return
+	}
+	if err = c.readFromUntil(c.conn, recordHeaderLen+n); err != nil {
+		if e, ok := err.(net.Error); !ok || !e.Temporary() {
+			c.rawConn.In.SetErrorLocked(err)
+		}
+		return
+	}
+
+	// Process message.
+	record := c.rawConn.RawInput.Next(recordHeaderLen + n)
+	data, typ, err = c.rawConn.In.Decrypt(record)
+	if err != nil {
+		err = c.rawConn.In.SetErrorLocked(c.sendAlert(uint8(err.(tls.AlertError))))
+		return
+	}
+	return
+}
+
+// retryReadRecord recurs into readRecordOrCCS to drop a non-advancing record, like
+// a warning alert, empty application_data, or a change_cipher_spec in TLS 1.3.
+func (c *Conn) retryReadRecord( /*expectChangeCipherSpec bool*/ ) error {
+	//c.retryCount++
+	//if c.retryCount > maxUselessRecords {
+	//	c.sendAlert(alertUnexpectedMessage)
+	//	return c.in.setErrorLocked(errors.New("tls: too many ignored records"))
+	//}
+	return c.readRecord( /*expectChangeCipherSpec*/ )
+}
+
+// atLeastReader reads from R, stopping with EOF once at least N bytes have been
+// read. It is different from an io.LimitedReader in that it doesn't cut short
+// the last Read call, and in that it considers an early EOF an error.
+type atLeastReader struct {
+	R io.Reader
+	N int64
+}
+
+func (r *atLeastReader) Read(p []byte) (int, error) {
+	if r.N <= 0 {
+		return 0, io.EOF
+	}
+	n, err := r.R.Read(p)
+	r.N -= int64(n) // won't underflow unless len(p) >= n > 9223372036854775809
+	if r.N > 0 && err == io.EOF {
+		return n, io.ErrUnexpectedEOF
+	}
+	if r.N <= 0 && err == nil {
+		return n, io.EOF
+	}
+	return n, err
+}
+
+// readFromUntil reads from r into c.rawConn.RawInput until c.rawConn.RawInput contains
+// at least n bytes or else returns an error.
+func (c *Conn) readFromUntil(r io.Reader, n int) error {
+	if c.rawConn.RawInput.Len() >= n {
+		return nil
+	}
+	needs := n - c.rawConn.RawInput.Len()
+	// There might be extra input waiting on the wire. Make a best effort
+	// attempt to fetch it so that it can be used in (*Conn).Read to
+	// "predict" closeNotify alerts.
+	c.rawConn.RawInput.Grow(needs + bytes.MinRead)
+	_, err := c.rawConn.RawInput.ReadFrom(&atLeastReader{r, int64(needs)})
+	return err
+}
+
+func (c *Conn) newRecordHeaderError(conn net.Conn, msg string) (err tls.RecordHeaderError) {
+	err.Msg = msg
+	err.Conn = conn
+	copy(err.RecordHeader[:], c.rawConn.RawInput.Bytes())
+	return err
+}

common/ktls/ktls_read_wait.go

@@ -0,0 +1,41 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"github.com/sagernet/sing/common/buf"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func (c *Conn) InitializeReadWaiter(options N.ReadWaitOptions) (needCopy bool) {
+	c.readWaitOptions = options
+	return false
+}
+
+func (c *Conn) WaitReadBuffer() (buffer *buf.Buffer, err error) {
+	c.rawConn.In.Lock()
+	defer c.rawConn.In.Unlock()
+	for c.rawConn.Input.Len() == 0 {
+		err = c.readRecord()
+		if err != nil {
+			return
+		}
+	}
+	buffer = c.readWaitOptions.NewBuffer()
+	n, err := c.rawConn.Input.Read(buffer.FreeBytes())
+	if err != nil {
+		buffer.Release()
+		return
+	}
+	buffer.Truncate(n)
+	if n != 0 && c.rawConn.Input.Len() == 0 && c.rawConn.Input.Len() > 0 &&
+		c.rawConn.RawInput.Bytes()[0] == recordTypeAlert {
+		_ = c.rawConn.ReadRecord()
+	}
+	c.readWaitOptions.PostReturn(buffer)
+	return
+}

common/ktls/ktls_stub.go

@@ -0,0 +1,13 @@
+//go:build !linux || !go1.25 || without_badtls
+
+package ktls
+
+import (
+	"os"
+
+	aTLS "github.com/sagernet/sing/common/tls"
+)
+
+func NewConn(conn aTLS.Conn, txOffload, rxOffload bool) (aTLS.Conn, error) {
+	return nil, os.ErrInvalid
+}

common/ktls/ktls_write.go

@@ -0,0 +1,154 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && go1.25 && !without_badtls
+
+package ktls
+
+import (
+	"crypto/cipher"
+	"crypto/tls"
+	"errors"
+	"net"
+)
+
+func (c *Conn) Write(b []byte) (int, error) {
+	if !c.kernelTx {
+		return c.Conn.Write(b)
+	}
+	// interlock with Close below
+	for {
+		x := c.rawConn.ActiveCall.Load()
+		if x&1 != 0 {
+			return 0, net.ErrClosed
+		}
+		if c.rawConn.ActiveCall.CompareAndSwap(x, x+2) {
+			break
+		}
+	}
+	defer c.rawConn.ActiveCall.Add(-2)
+
+	//if err := c.Conn.HandshakeContext(context.Background()); err != nil {
+	//	return 0, err
+	//}
+
+	c.rawConn.Out.Lock()
+	defer c.rawConn.Out.Unlock()
+
+	if err := *c.rawConn.Out.Err; err != nil {
+		return 0, err
+	}
+
+	if !c.rawConn.IsHandshakeComplete.Load() {
+		return 0, tls.AlertError(alertInternalError)
+	}
+
+	if *c.rawConn.CloseNotifySent {
+		// return 0, errShutdown
+		return 0, errors.New("tls: protocol is shutdown")
+	}
+
+	// TLS 1.0 is susceptible to a chosen-plaintext
+	// attack when using block mode ciphers due to predictable IVs.
+	// This can be prevented by splitting each Application Data
+	// record into two records, effectively randomizing the RawIV.
+	//
+	// https://www.openssl.org/~bodo/tls-cbc.txt
+	// https://bugzilla.mozilla.org/show_bug.cgi?id=665814
+	// https://www.imperialviolet.org/2012/01/15/beastfollowup.html
+
+	var m int
+	if len(b) > 1 && *c.rawConn.Vers == tls.VersionTLS10 {
+		if _, ok := (*c.rawConn.Out.Cipher).(cipher.BlockMode); ok {
+			n, err := c.writeRecordLocked(recordTypeApplicationData, b[:1])
+			if err != nil {
+				return n, c.rawConn.Out.SetErrorLocked(err)
+			}
+			m, b = 1, b[1:]
+		}
+	}
+
+	n, err := c.writeRecordLocked(recordTypeApplicationData, b)
+	return n + m, c.rawConn.Out.SetErrorLocked(err)
+}
+
+func (c *Conn) writeRecordLocked(typ uint16, data []byte) (n int, err error) {
+	if !c.kernelTx {
+		return c.rawConn.WriteRecordLocked(typ, data)
+	}
+	/*for len(data) > 0 {
+		m := len(data)
+		if maxPayload := c.maxPayloadSizeForWrite(typ); m > maxPayload {
+			m = maxPayload
+		}
+		_, err = c.writeKernelRecord(typ, data[:m])
+		if err != nil {
+			return
+		}
+		n += m
+		data = data[m:]
+	}*/
+	return c.writeKernelRecord(typ, data)
+}
+
+const (
+	// tcpMSSEstimate is a conservative estimate of the TCP maximum segment
+	// size (MSS). A constant is used, rather than querying the kernel for
+	// the actual MSS, to avoid complexity. The value here is the IPv6
+	// minimum MTU (1280 bytes) minus the overhead of an IPv6 header (40
+	// bytes) and a TCP header with timestamps (32 bytes).
+	tcpMSSEstimate = 1208
+
+	// recordSizeBoostThreshold is the number of bytes of application data
+	// sent after which the TLS record size will be increased to the
+	// maximum.
+	recordSizeBoostThreshold = 128 * 1024
+)
+
+func (c *Conn) maxPayloadSizeForWrite(typ uint16) int {
+	if /*c.config.DynamicRecordSizingDisabled ||*/ typ != recordTypeApplicationData {
+		return maxPlaintext
+	}
+
+	if *c.rawConn.PacketsSent >= recordSizeBoostThreshold {
+		return maxPlaintext
+	}
+
+	// Subtract TLS overheads to get the maximum payload size.
+	payloadBytes := tcpMSSEstimate - recordHeaderLen - c.rawConn.Out.ExplicitNonceLen()
+	if rawCipher := *c.rawConn.Out.Cipher; rawCipher != nil {
+		switch ciph := rawCipher.(type) {
+		case cipher.Stream:
+			payloadBytes -= (*c.rawConn.Out.Mac).Size()
+		case cipher.AEAD:
+			payloadBytes -= ciph.Overhead()
+		/*case cbcMode:
+		blockSize := ciph.BlockSize()
+		// The payload must fit in a multiple of blockSize, with
+		// room for at least one padding byte.
+		payloadBytes = (payloadBytes & ^(blockSize - 1)) - 1
+		// The RawMac is appended before padding so affects the
+		// payload size directly.
+		payloadBytes -= c.out.mac.Size()*/
+		default:
+			panic("unknown cipher type")
+		}
+	}
+	if *c.rawConn.Vers == tls.VersionTLS13 {
+		payloadBytes-- // encrypted ContentType
+	}
+
+	// Allow packet growth in arithmetic progression up to max.
+	pkt := *c.rawConn.PacketsSent
+	*c.rawConn.PacketsSent++
+	if pkt > 1000 {
+		return maxPlaintext // avoid overflow in multiply below
+	}
+
+	n := payloadBytes * int(pkt+1)
+	if n > maxPlaintext {
+		n = maxPlaintext
+	}
+	return n
+}

common/tls/client.go

@@ -8,8 +8,10 @@ import (
 	"os"
 
 	"github.com/sagernet/sing-box/common/badtls"
+	"github.com/sagernet/sing-box/common/ktls"
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 	aTLS "github.com/sagernet/sing/common/tls"
@@ -45,6 +47,12 @@ func ClientHandshake(ctx context.Context, conn net.Conn, config Config) (Conn, e
 	if err != nil {
 		return nil, err
 	}
+	if kConfig, isKConfig := config.(KTLSCapableConfig); isKConfig && (kConfig.KernelTx() || kConfig.KernelRx()) {
+		if !C.IsLinux {
+			return nil, E.New("kTLS is only supported on Linux")
+		}
+		return ktls.NewConn(tlsConn, kConfig.KernelTx(), kConfig.KernelRx())
+	}
 	readWaitConn, err := badtls.NewReadWaitConn(tlsConn)
 	if err == nil {
 		return readWaitConn, nil

common/tls/config.go

@@ -21,6 +21,12 @@ type (
 	CurveID         = tls.CurveID
 )
 
+type KTLSCapableConfig interface {
+	Config
+	KernelTx() bool
+	KernelRx() bool
+}
+
 func ParseTLSVersion(version string) (uint16, error) {
 	switch version {
 	case "1.0":

common/tls/server.go

@@ -6,9 +6,11 @@ import (
 	"os"
 
 	"github.com/sagernet/sing-box/common/badtls"
+	"github.com/sagernet/sing-box/common/ktls"
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
 	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
 	aTLS "github.com/sagernet/sing/common/tls"
 )
 
@@ -29,6 +31,12 @@ func ServerHandshake(ctx context.Context, conn net.Conn, config ServerConfig) (C
 	if err != nil {
 		return nil, err
 	}
+	if kConfig, isKConfig := config.(KTLSCapableConfig); isKConfig && (kConfig.KernelTx() || kConfig.KernelRx()) {
+		if !C.IsLinux {
+			return nil, E.New("kTLS is only supported on Linux")
+		}
+		return ktls.NewConn(tlsConn, kConfig.KernelTx(), kConfig.KernelRx())
+	}
 	readWaitConn, err := badtls.NewReadWaitConn(tlsConn)
 	if err == nil {
 		return readWaitConn, nil

common/tls/std_client.go

@@ -22,6 +22,7 @@ type STDClientConfig struct {
 	fragment              bool
 	fragmentFallbackDelay time.Duration
 	recordFragment        bool
+	kernelTx, kernelRx    bool
 }
 
 func (c *STDClientConfig) ServerName() string {
@@ -52,7 +53,15 @@ func (c *STDClientConfig) Client(conn net.Conn) (Conn, error) {
 }
 
 func (c *STDClientConfig) Clone() Config {
-	return &STDClientConfig{c.ctx, c.config.Clone(), c.fragment, c.fragmentFallbackDelay, c.recordFragment}
+	return &STDClientConfig{
+		ctx:                   c.ctx,
+		config:                c.config.Clone(),
+		fragment:              c.fragment,
+		fragmentFallbackDelay: c.fragmentFallbackDelay,
+		recordFragment:        c.recordFragment,
+		kernelTx:              c.kernelTx,
+		kernelRx:              c.kernelRx,
+	}
 }
 
 func (c *STDClientConfig) ECHConfigList() []byte {
@@ -63,6 +72,14 @@ func (c *STDClientConfig) SetECHConfigList(EncryptedClientHelloConfigList []byte
 	c.config.EncryptedClientHelloConfigList = EncryptedClientHelloConfigList
 }
 
+func (c *STDClientConfig) KernelTx() bool {
+	return c.kernelTx
+}
+
+func (c *STDClientConfig) KernelRx() bool {
+	return c.kernelRx
+}
+
 func NewSTDClient(ctx context.Context, serverAddress string, options option.OutboundTLSOptions) (Config, error) {
 	var serverName string
 	if options.ServerName != "" {
@@ -146,7 +163,15 @@ func NewSTDClient(ctx context.Context, serverAddress string, options option.Outb
 		}
 		tlsConfig.RootCAs = certPool
 	}
-	stdConfig := &STDClientConfig{ctx, &tlsConfig, options.Fragment, time.Duration(options.FragmentFallbackDelay), options.RecordFragment}
+	stdConfig := &STDClientConfig{
+		ctx:                   ctx,
+		config:                &tlsConfig,
+		fragment:              options.Fragment,
+		fragmentFallbackDelay: time.Duration(options.FragmentFallbackDelay),
+		recordFragment:        options.RecordFragment,
+		kernelTx:              options.KernelTx,
+		kernelRx:              options.KernelRx,
+	}
 	if options.ECH != nil && options.ECH.Enabled {
 		return parseECHClientConfig(ctx, stdConfig, options)
 	} else {

common/tls/std_server.go

@@ -20,15 +20,16 @@ import (
 var errInsecureUnused = E.New("tls: insecure unused")
 
 type STDServerConfig struct {
-	config          *tls.Config
+	config             *tls.Config
-	logger          log.Logger
+	logger             log.Logger
-	acmeService     adapter.SimpleLifecycle
+	kernelTx, kernelRx bool
-	certificate     []byte
+	acmeService        adapter.SimpleLifecycle
-	key             []byte
+	certificate        []byte
-	certificatePath string
+	key                []byte
-	keyPath         string
+	certificatePath    string
-	echKeyPath      string
+	keyPath            string
-	watcher         *fswatch.Watcher
+	echKeyPath         string
+	watcher            *fswatch.Watcher
 }
 
 func (c *STDServerConfig) ServerName() string {
@@ -69,10 +70,20 @@ func (c *STDServerConfig) Server(conn net.Conn) (Conn, error) {
 
 func (c *STDServerConfig) Clone() Config {
 	return &STDServerConfig{
-		config: c.config.Clone(),
+		config:   c.config.Clone(),
+		kernelTx: c.kernelTx,
+		kernelRx: c.kernelRx,
 	}
 }
 
+func (c *STDServerConfig) KernelTx() bool {
+	return c.kernelTx
+}
+
+func (c *STDServerConfig) KernelRx() bool {
+	return c.kernelRx
+}
+
 func (c *STDServerConfig) Start() error {
 	if c.acmeService != nil {
 		return c.acmeService.Start()
@@ -265,6 +276,8 @@ func NewSTDServer(ctx context.Context, logger log.Logger, options option.Inbound
 	return &STDServerConfig{
 		config:          tlsConfig,
 		logger:          logger,
+		kernelTx:        options.KernelTx,
+		kernelRx:        options.KernelRx,
 		acmeService:     acmeService,
 		certificate:     certificate,
 		key:             key,

common/tls/utls_client.go

@@ -29,6 +29,8 @@ type UTLSClientConfig struct {
 	fragment              bool
 	fragmentFallbackDelay time.Duration
 	recordFragment        bool
+	kernelTx              bool
+	kernelRx              bool
 }
 
 func (c *UTLSClientConfig) ServerName() string {
@@ -67,7 +69,7 @@ func (c *UTLSClientConfig) SetSessionIDGenerator(generator func(clientHello []by
 
 func (c *UTLSClientConfig) Clone() Config {
 	return &UTLSClientConfig{
-		c.ctx, c.config.Clone(), c.id, c.fragment, c.fragmentFallbackDelay, c.recordFragment,
+		c.ctx, c.config.Clone(), c.id, c.fragment, c.fragmentFallbackDelay, c.recordFragment, c.kernelTx, c.kernelRx,
 	}
 }
 
@@ -79,6 +81,14 @@ func (c *UTLSClientConfig) SetECHConfigList(EncryptedClientHelloConfigList []byt
 	c.config.EncryptedClientHelloConfigList = EncryptedClientHelloConfigList
 }
 
+func (c *UTLSClientConfig) KernelTx() bool {
+	return c.kernelTx
+}
+
+func (c *UTLSClientConfig) KernelRx() bool {
+	return c.kernelRx
+}
+
 type utlsConnWrapper struct {
 	*utls.UConn
 }
@@ -214,7 +224,12 @@ func NewUTLSClient(ctx context.Context, serverAddress string, options option.Out
 	if err != nil {
 		return nil, err
 	}
-	uConfig := &UTLSClientConfig{ctx, &tlsConfig, id, options.Fragment, time.Duration(options.FragmentFallbackDelay), options.RecordFragment}
+	uConfig := &UTLSClientConfig{ctx, &tlsConfig, id, options.Fragment, time.Duration(options.FragmentFallbackDelay), options.RecordFragment, options.KernelTx, options.KernelRx}
+	if uConfig.kernelTx || uConfig.kernelRx {
+		if options.Reality != nil && options.Reality.Enabled {
+			return nil, E.New("Reality is conflict with kTLS")
+		}
+	}
 	if options.ECH != nil && options.ECH.Enabled {
 		if options.Reality != nil && options.Reality.Enabled {
 			return nil, E.New("Reality is conflict with ECH")

go.mod

@@ -4,6 +4,7 @@ go 1.23.1
 
 require (
 	github.com/anytls/sing-anytls v0.0.8
+	github.com/blang/semver/v4 v4.0.0
 	github.com/caddyserver/certmagic v0.23.0
 	github.com/coder/websocket v1.8.13
 	github.com/cretz/bine v0.2.0
@@ -27,7 +28,7 @@ require (
 	github.com/sagernet/gomobile v0.1.8
 	github.com/sagernet/gvisor v0.0.0-20250822052253-5558536cf237
 	github.com/sagernet/quic-go v0.52.0-beta.1
-	github.com/sagernet/sing v0.7.8-0.20250906004629-421beb6473ea
+	github.com/sagernet/sing v0.7.8-0.20250907125815-3d24f9b5ff7c
 	github.com/sagernet/sing-mux v0.3.3
 	github.com/sagernet/sing-quic v0.5.1
 	github.com/sagernet/sing-shadowsocks v0.2.8

go.sum

@@ -12,6 +12,8 @@ github.com/anytls/sing-anytls v0.0.8 h1:1u/fnH1HoeeMV5mX7/eUOjLBvPdkd1UJRmXiRi6V
 github.com/anytls/sing-anytls v0.0.8/go.mod h1:7rjN6IukwysmdusYsrV51Fgu1uW6vsrdd6ctjnEAln8=
 github.com/bits-and-blooms/bitset v1.13.0 h1:bAQ9OPNFYbGHV6Nez0tmNI0RiEu7/hxlYJRUA0wFAVE=
 github.com/bits-and-blooms/bitset v1.13.0/go.mod h1:7hO7Gc7Pp1vODcmWvKMRA9BNmbv6a/7QIWpPxHddWR8=
+github.com/blang/semver/v4 v4.0.0 h1:1PFHFE6yCCTv8C1TeyNNarDzntLi7wMI5i/pzqYIsAM=
+github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
 github.com/caddyserver/certmagic v0.23.0 h1:CfpZ/50jMfG4+1J/u2LV6piJq4HOfO6ppOnOf7DkFEU=
 github.com/caddyserver/certmagic v0.23.0/go.mod h1:9mEZIWqqWoI+Gf+4Trh04MOVPD0tGSxtqsxg87hAIH4=
 github.com/caddyserver/zerossl v0.1.3 h1:onS+pxp3M8HnHpN5MMbOMyNjmTheJyWRaZYwn+YTAyA=
@@ -167,8 +169,8 @@ github.com/sagernet/nftables v0.3.0-beta.4/go.mod h1:OQXAjvjNGGFxaTgVCSTRIhYB5/l
 github.com/sagernet/quic-go v0.52.0-beta.1 h1:hWkojLg64zjV+MJOvJU/kOeWndm3tiEfBLx5foisszs=
 github.com/sagernet/quic-go v0.52.0-beta.1/go.mod h1:OV+V5kEBb8kJS7k29MzDu6oj9GyMc7HA07sE1tedxz4=
 github.com/sagernet/sing v0.6.9/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
-github.com/sagernet/sing v0.7.8-0.20250906004629-421beb6473ea h1:CDRl4q5Y2dM6MQE1MwukhrxbObfK/rj0QtK7vnJhST0=
+github.com/sagernet/sing v0.7.8-0.20250907125815-3d24f9b5ff7c h1:7jbIoVt3p1vlgQoyWIlzRvwInNwDxe6+tSJME07LTmI=
-github.com/sagernet/sing v0.7.8-0.20250906004629-421beb6473ea/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
+github.com/sagernet/sing v0.7.8-0.20250907125815-3d24f9b5ff7c/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
 github.com/sagernet/sing-mux v0.3.3 h1:YFgt9plMWzH994BMZLmyKL37PdIVaIilwP0Jg+EcLfw=
 github.com/sagernet/sing-mux v0.3.3/go.mod h1:pht8iFY4c9Xltj7rhVd208npkNaeCxzyXCgulDPLUDA=
 github.com/sagernet/sing-quic v0.5.1 h1:o+mX/schfy6fbbU2rnb6ouUYOL+iUBjA4jOZqyIvDsU=

option/tls.go

@@ -14,6 +14,8 @@ type InboundTLSOptions struct {
 	CertificatePath string                     `json:"certificate_path,omitempty"`
 	Key             badoption.Listable[string] `json:"key,omitempty"`
 	KeyPath         string                     `json:"key_path,omitempty"`
+	KernelTx        bool                       `json:"kernel_tx,omitempty"`
+	KernelRx        bool                       `json:"kernel_rx,omitempty"`
 	ACME            *InboundACMEOptions        `json:"acme,omitempty"`
 	ECH             *InboundECHOptions         `json:"ech,omitempty"`
 	Reality         *InboundRealityOptions     `json:"reality,omitempty"`
@@ -50,6 +52,8 @@ type OutboundTLSOptions struct {
 	Fragment              bool                       `json:"fragment,omitempty"`
 	FragmentFallbackDelay badoption.Duration         `json:"fragment_fallback_delay,omitempty"`
 	RecordFragment        bool                       `json:"record_fragment,omitempty"`
+	KernelTx              bool                       `json:"kernel_tx,omitempty"`
+	KernelRx              bool                       `json:"kernel_rx,omitempty"`
 	ECH                   *OutboundECHOptions        `json:"ech,omitempty"`
 	UTLS                  *OutboundUTLSOptions       `json:"utls,omitempty"`
 	Reality               *OutboundRealityOptions    `json:"reality,omitempty"`

release/local/debug.sh

@@ -13,7 +13,7 @@ pushd $PROJECT
 git fetch
 git reset FETCH_HEAD --hard
 git clean -fdx
-go install -v -trimpath -ldflags "-s -w -buildid=" -tags with_quic,with_acme,debug ./cmd/sing-box
+go install -v -trimpath -ldflags "-s -w -buildid= -checklinkname=0" -tags with_quic,with_acme,debug ./cmd/sing-box
 popd
 
 sudo systemctl stop sing-box

release/local/install.sh

@@ -10,7 +10,7 @@ DIR=$(dirname "$0")
 PROJECT=$DIR/../..
 
 pushd $PROJECT
-go install -v -trimpath -ldflags "-s -w -buildid=" -tags with_quic,with_wireguard,with_acme ./cmd/sing-box
+go install -v -trimpath -ldflags "-s -w -buildid= -checklinkname=0" -tags with_quic,with_wireguard,with_acme ./cmd/sing-box
 popd
 
 sudo cp $(go env GOPATH)/bin/sing-box /usr/local/bin/

release/local/reinstall.sh

@@ -10,7 +10,7 @@ DIR=$(dirname "$0")
 PROJECT=$DIR/../..
 
 pushd $PROJECT
-go install -v -trimpath -ldflags "-s -w -buildid=" -tags with_quic,with_wireguard,with_acme ./cmd/sing-box
+go install -v -trimpath -ldflags "-s -w -buildid= -checklinkname=0" -tags with_quic,with_wireguard,with_acme ./cmd/sing-box
 popd
 
 sudo systemctl stop sing-box

route/conn.go

@@ -102,6 +102,8 @@ func (m *ConnectionManager) NewConnection(ctx context.Context, this N.Dialer, co
 		m.connections.Remove(element)
 	})
 	var done atomic.Bool
+	m.preConnectionCopy(ctx, conn, remoteConn, false, &done, onClose)
+	m.preConnectionCopy(ctx, remoteConn, conn, true, &done, onClose)
 	go m.connectionCopy(ctx, conn, remoteConn, false, &done, onClose)
 	go m.connectionCopy(ctx, remoteConn, conn, true, &done, onClose)
 }
@@ -224,6 +226,24 @@ func (m *ConnectionManager) NewPacketConnection(ctx context.Context, this N.Dial
 	go m.packetConnectionCopy(ctx, destination, conn, true, &done, onClose)
 }
 
+func (m *ConnectionManager) preConnectionCopy(ctx context.Context, source net.Conn, destination net.Conn, direction bool, done *atomic.Bool, onClose N.CloseHandlerFunc) {
+	if earlyConn, isEarlyConn := common.Cast[N.EarlyConn](destination); isEarlyConn && earlyConn.NeedHandshake() {
+		err := m.connectionCopyEarly(source, destination)
+		if err != nil {
+			if done.Swap(true) {
+				onClose(err)
+			}
+			common.Close(source, destination)
+			if !direction {
+				m.logger.ErrorContext(ctx, "connection upload handshake: ", err)
+			} else {
+				m.logger.ErrorContext(ctx, "connection download handshake: ", err)
+			}
+			return
+		}
+	}
+}
+
 func (m *ConnectionManager) connectionCopy(ctx context.Context, source net.Conn, destination net.Conn, direction bool, done *atomic.Bool, onClose N.CloseHandlerFunc) {
 	var (
 		sourceReader      io.Reader = source
@@ -262,21 +282,7 @@ func (m *ConnectionManager) connectionCopy(ctx context.Context, source net.Conn,
 		}
 		break
 	}
-	if earlyConn, isEarlyConn := common.Cast[N.EarlyConn](destinationWriter); isEarlyConn && earlyConn.NeedHandshake() {
+
-		err := m.connectionCopyEarly(source, destination)
-		if err != nil {
-			if done.Swap(true) {
-				onClose(err)
-			}
-			common.Close(source, destination)
-			if !direction {
-				m.logger.ErrorContext(ctx, "connection upload handshake: ", err)
-			} else {
-				m.logger.ErrorContext(ctx, "connection download handshake: ", err)
-			}
-			return
-		}
-	}
 	_, err := bufio.CopyWithCounters(destinationWriter, sourceReader, source, readCounters, writeCounters, bufio.DefaultIncreaseBufferAfter, bufio.DefaultBatchSize)
 	if err != nil {
 		common.Close(source, destination)

transport/trojan/protocol.go

@@ -83,6 +83,14 @@ func (c *ClientConn) Upstream() any {
 	return c.ExtendedConn
 }
 
+func (c *ClientConn) ReaderReplaceable() bool {
+	return c.headerWritten
+}
+
+func (c *ClientConn) WriterReplaceable() bool {
+	return c.headerWritten
+}
+
 type ClientPacketConn struct {
 	net.Conn
 	access          sync.Mutex