feat: support kcptun plugin for ss client/server

adapter/outbound/shadowsocks.go

@@ -13,6 +13,7 @@ import (
 	C "github.com/metacubex/mihomo/constant"
 	"github.com/metacubex/mihomo/ntp"
 	gost "github.com/metacubex/mihomo/transport/gost-plugin"
+	"github.com/metacubex/mihomo/transport/kcptun"
 	"github.com/metacubex/mihomo/transport/restls"
 	obfs "github.com/metacubex/mihomo/transport/simple-obfs"
 	shadowtls "github.com/metacubex/mihomo/transport/sing-shadowtls"
@@ -36,6 +37,7 @@ type ShadowSocks struct {
 	gostOption      *gost.Option
 	shadowTLSOption *shadowtls.ShadowTLSOption
 	restlsConfig    *restls.Config
+	kcptunClient    *kcptun.Client
 }
 
 type ShadowSocksOption struct {
@@ -106,6 +108,32 @@ type restlsOption struct {
 	RestlsScript string `obfs:"restls-script,omitempty"`
 }
 
+type kcpTunOption struct {
+	Key          string `obfs:"key,omitempty"`
+	Crypt        string `obfs:"crypt,omitempty"`
+	Mode         string `obfs:"mode,omitempty"`
+	Conn         int    `obfs:"conn,omitempty"`
+	AutoExpire   int    `obfs:"autoexpire,omitempty"`
+	ScavengeTTL  int    `obfs:"scavengettl,omitempty"`
+	MTU          int    `obfs:"mtu,omitempty"`
+	SndWnd       int    `obfs:"sndwnd,omitempty"`
+	RcvWnd       int    `obfs:"rcvwnd,omitempty"`
+	DataShard    int    `obfs:"datashard,omitempty"`
+	ParityShard  int    `obfs:"parityshard,omitempty"`
+	DSCP         int    `obfs:"dscp,omitempty"`
+	NoComp       bool   `obfs:"nocomp,omitempty"`
+	AckNodelay   bool   `obfs:"acknodelay,omitempty"`
+	NoDelay      int    `obfs:"nodelay,omitempty"`
+	Interval     int    `obfs:"interval,omitempty"`
+	Resend       int    `obfs:"resend,omitempty"`
+	NoCongestion int    `obfs:"nc,omitempty"`
+	SockBuf      int    `obfs:"sockbuf,omitempty"`
+	SmuxVer      int    `obfs:"smuxver,omitempty"`
+	SmuxBuf      int    `obfs:"smuxbuf,omitempty"`
+	StreamBuf    int    `obfs:"streambuf,omitempty"`
+	KeepAlive    int    `obfs:"keepalive,omitempty"`
+}
+
 // StreamConnContext implements C.ProxyAdapter
 func (ss *ShadowSocks) StreamConnContext(ctx context.Context, c net.Conn, metadata *C.Metadata) (_ net.Conn, err error) {
 	useEarly := false
@@ -174,7 +202,27 @@ func (ss *ShadowSocks) DialContextWithDialer(ctx context.Context, dialer C.Diale
 			return nil, err
 		}
 	}
-	c, err := dialer.DialContext(ctx, "tcp", ss.addr)
+	var c net.Conn
+	if ss.kcptunClient != nil {
+		c, err = ss.kcptunClient.OpenStream(ctx, func(ctx context.Context) (net.PacketConn, net.Addr, error) {
+			if err = ss.ResolveUDP(ctx, metadata); err != nil {
+				return nil, nil, err
+			}
+			addr, err := resolveUDPAddr(ctx, "udp", ss.addr, ss.prefer)
+			if err != nil {
+				return nil, nil, err
+			}
+
+			pc, err := dialer.ListenPacket(ctx, "udp", "", addr.AddrPort())
+			if err != nil {
+				return nil, nil, err
+			}
+
+			return pc, addr, nil
+		})
+	} else {
+		c, err = dialer.DialContext(ctx, "tcp", ss.addr)
+	}
 	if err != nil {
 		return nil, fmt.Errorf("%s connect error: %w", ss.addr, err)
 	}
@@ -256,6 +304,13 @@ func (ss *ShadowSocks) SupportUOT() bool {
 	return ss.option.UDPOverTCP
 }
 
+func (ss *ShadowSocks) Close() error {
+	if ss.kcptunClient != nil {
+		return ss.kcptunClient.Close()
+	}
+	return nil
+}
+
 func NewShadowSocks(option ShadowSocksOption) (*ShadowSocks, error) {
 	addr := net.JoinHostPort(option.Server, strconv.Itoa(option.Port))
 	method, err := shadowsocks.CreateMethod(option.Cipher, shadowsocks.MethodOptions{
@@ -271,6 +326,7 @@ func NewShadowSocks(option ShadowSocksOption) (*ShadowSocks, error) {
 	var obfsOption *simpleObfsOption
 	var shadowTLSOpt *shadowtls.ShadowTLSOption
 	var restlsConfig *restls.Config
+	var kcptunClient *kcptun.Client
 	obfsMode := ""
 
 	decoder := structure.NewDecoder(structure.Option{TagName: "obfs", WeaklyTypedInput: true})
@@ -384,6 +440,39 @@ func NewShadowSocks(option ShadowSocksOption) (*ShadowSocks, error) {
 			return nil, fmt.Errorf("ss %s initialize restls-plugin error: %w", addr, err)
 		}
 
+	} else if option.Plugin == kcptun.Mode {
+		obfsMode = kcptun.Mode
+		kcptunOpt := &kcpTunOption{}
+		if err := decoder.Decode(option.PluginOpts, kcptunOpt); err != nil {
+			return nil, fmt.Errorf("ss %s initialize kcptun-plugin error: %w", addr, err)
+		}
+
+		kcptunClient = kcptun.NewClient(kcptun.Config{
+			Key:          kcptunOpt.Key,
+			Crypt:        kcptunOpt.Crypt,
+			Mode:         kcptunOpt.Mode,
+			Conn:         kcptunOpt.Conn,
+			AutoExpire:   kcptunOpt.AutoExpire,
+			ScavengeTTL:  kcptunOpt.ScavengeTTL,
+			MTU:          kcptunOpt.MTU,
+			SndWnd:       kcptunOpt.SndWnd,
+			RcvWnd:       kcptunOpt.RcvWnd,
+			DataShard:    kcptunOpt.DataShard,
+			ParityShard:  kcptunOpt.ParityShard,
+			DSCP:         kcptunOpt.DSCP,
+			NoComp:       kcptunOpt.NoComp,
+			AckNodelay:   kcptunOpt.AckNodelay,
+			NoDelay:      kcptunOpt.NoDelay,
+			Interval:     kcptunOpt.Interval,
+			Resend:       kcptunOpt.Resend,
+			NoCongestion: kcptunOpt.NoCongestion,
+			SockBuf:      kcptunOpt.SockBuf,
+			SmuxVer:      kcptunOpt.SmuxVer,
+			SmuxBuf:      kcptunOpt.SmuxBuf,
+			StreamBuf:    kcptunOpt.StreamBuf,
+			KeepAlive:    kcptunOpt.KeepAlive,
+		})
+		option.UDPOverTCP = true // must open uot
 	}
 	switch option.UDPOverTCPVersion {
 	case uot.Version, uot.LegacyVersion:
@@ -414,5 +503,6 @@ func NewShadowSocks(option ShadowSocksOption) (*ShadowSocks, error) {
 		obfsOption:      obfsOption,
 		shadowTLSOption: shadowTLSOpt,
 		restlsConfig:    restlsConfig,
+		kcptunClient:    kcptunClient,
 	}, nil
 }