chore: support TFO for outbounds

adapter/outbound/base.go

@@ -140,10 +140,15 @@ func (b *Base) DialOptions(opts ...dialer.Option) []dialer.Option {
 	default:
 	}
 
+	if b.tfo {
+		opts = append(opts, dialer.WithTFO(true))
+	}
+
 	return opts
 }
 
 type BasicOption struct {
+	TFO         bool   `proxy:"tfo,omitempty" group:"tfo,omitempty"`
 	Interface   string `proxy:"interface-name,omitempty" group:"interface-name,omitempty"`
 	RoutingMark int    `proxy:"routing-mark,omitempty" group:"routing-mark,omitempty"`
 	IPVersion   string `proxy:"ip-version,omitempty" group:"ip-version,omitempty"`

adapter/outbound/http.go

@@ -170,6 +170,7 @@ func NewHttp(option HttpOption) (*Http, error) {
 			name:   option.Name,
 			addr:   net.JoinHostPort(option.Server, strconv.Itoa(option.Port)),
 			tp:     C.Http,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/shadowsocks.go

@@ -252,6 +252,7 @@ func NewShadowSocks(option ShadowSocksOption) (*ShadowSocks, error) {
 			addr:   addr,
 			tp:     C.Shadowsocks,
 			udp:    option.UDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/shadowsocksr.go

@@ -163,6 +163,7 @@ func NewShadowSocksR(option ShadowSocksROption) (*ShadowSocksR, error) {
 			addr:   addr,
 			tp:     C.ShadowsocksR,
 			udp:    option.UDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/snell.go

@@ -167,6 +167,7 @@ func NewSnell(option SnellOption) (*Snell, error) {
 			addr:   addr,
 			tp:     C.Snell,
 			udp:    option.UDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/socks5.go

@@ -182,6 +182,7 @@ func NewSocks5(option Socks5Option) (*Socks5, error) {
 			addr:   net.JoinHostPort(option.Server, strconv.Itoa(option.Port)),
 			tp:     C.Socks5,
 			udp:    option.UDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/trojan.go

@@ -250,6 +250,7 @@ func NewTrojan(option TrojanOption) (*Trojan, error) {
 			addr:   addr,
 			tp:     C.Trojan,
 			udp:    option.UDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/vless.go

@@ -510,6 +510,7 @@ func NewVless(option VlessOption) (*Vless, error) {
 			tp:     C.Vless,
 			udp:    option.UDP,
 			xudp:   option.XUDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

adapter/outbound/vmess.go

@@ -387,6 +387,7 @@ func NewVmess(option VmessOption) (*Vmess, error) {
 			tp:     C.Vmess,
 			udp:    option.UDP,
 			xudp:   option.XUDP,
+			tfo:    option.TFO,
 			iface:  option.Interface,
 			rmark:  option.RoutingMark,
 			prefer: C.NewDNSPrefer(option.IPVersion),

component/dialer/dialer.go

@@ -118,7 +118,11 @@ func dialContext(ctx context.Context, network string, destination netip.Addr, po
 		return nil, ErrorDisableIPv6
 	}
 
-	return dialer.DialContext(ctx, network, net.JoinHostPort(destination.String(), port))
+	address := net.JoinHostPort(destination.String(), port)
+	if opt.tfo {
+		return dialTFO(ctx, *dialer, network, address)
+	}
+	return dialer.DialContext(ctx, network, address)
 }
 
 func singleDialContext(ctx context.Context, network string, address string, opt *option) (net.Conn, error) {

component/dialer/options.go

@@ -18,6 +18,7 @@ type option struct {
 	routingMark   int
 	network       int
 	prefer        int
+	tfo           bool
 	resolver      resolver.Resolver
 }
 
@@ -69,6 +70,12 @@ func WithOnlySingleStack(isIPv4 bool) Option {
 	}
 }
 
+func WithTFO(tfo bool) Option {
+	return func(opt *option) {
+		opt.tfo = tfo
+	}
+}
+
 func WithOption(o option) Option {
 	return func(opt *option) {
 		*opt = o

component/dialer/tfo.go

@@ -0,0 +1,119 @@
+package dialer
+
+import (
+	"context"
+	"github.com/sagernet/tfo-go"
+	"io"
+	"net"
+	"time"
+)
+
+type tfoConn struct {
+	net.Conn
+	closed bool
+	dialed chan bool
+	cancel context.CancelFunc
+	ctx    context.Context
+	dialFn func(ctx context.Context, earlyData []byte) (net.Conn, error)
+}
+
+func (c *tfoConn) Dial(earlyData []byte) (err error) {
+	c.Conn, err = c.dialFn(c.ctx, earlyData)
+	if err != nil {
+		return
+	}
+	c.dialed <- true
+	return err
+}
+
+func (c *tfoConn) Read(b []byte) (n int, err error) {
+	if c.closed {
+		return 0, io.ErrClosedPipe
+	}
+	if c.Conn == nil {
+		select {
+		case <-c.ctx.Done():
+			return 0, io.ErrUnexpectedEOF
+		case <-c.dialed:
+		}
+	}
+	return c.Conn.Read(b)
+}
+
+func (c *tfoConn) Write(b []byte) (n int, err error) {
+	if c.closed {
+		return 0, io.ErrClosedPipe
+	}
+	if c.Conn == nil {
+		if err := c.Dial(b); err != nil {
+			return 0, err
+		}
+		return len(b), nil
+	}
+
+	return c.Conn.Write(b)
+}
+
+func (c *tfoConn) Close() error {
+	c.closed = true
+	c.cancel()
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.Close()
+}
+
+func (c *tfoConn) LocalAddr() net.Addr {
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.LocalAddr()
+}
+
+func (c *tfoConn) RemoteAddr() net.Addr {
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.RemoteAddr()
+}
+
+func (c *tfoConn) SetDeadline(t time.Time) error {
+	if err := c.SetReadDeadline(t); err != nil {
+		return err
+	}
+	return c.SetWriteDeadline(t)
+}
+
+func (c *tfoConn) SetReadDeadline(t time.Time) error {
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.SetReadDeadline(t)
+}
+
+func (c *tfoConn) SetWriteDeadline(t time.Time) error {
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.SetWriteDeadline(t)
+}
+
+func (c *tfoConn) Upstream() any {
+	if c.Conn == nil { // ensure return a nil interface not an interface with nil value
+		return nil
+	}
+	return c.Conn
+}
+
+func dialTFO(ctx context.Context, netDialer net.Dialer, network, address string) (net.Conn, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	dialer := tfo.Dialer{Dialer: netDialer, DisableTFO: false}
+	return &tfoConn{
+		dialed: make(chan bool, 1),
+		cancel: cancel,
+		ctx:    ctx,
+		dialFn: func(ctx context.Context, earlyData []byte) (net.Conn, error) {
+			return dialer.DialContext(ctx, network, address, earlyData)
+		},
+	}, nil
+}