package sniffing import ( "bufio" "bytes" "context" "crypto" "crypto/tls" "crypto/x509" "encoding/hex" "errors" "fmt" "io" "math" "net" "net/http" "net/http/httputil" "strings" "time" "github.com/go-gost/core/bypass" "github.com/go-gost/core/logger" "github.com/go-gost/core/observer/stats" "github.com/go-gost/core/recorder" dissector "github.com/go-gost/tls-dissector" xbypass "github.com/go-gost/x/bypass" ctxvalue "github.com/go-gost/x/ctx" xio "github.com/go-gost/x/internal/io" xnet "github.com/go-gost/x/internal/net" xhttp "github.com/go-gost/x/internal/net/http" tls_util "github.com/go-gost/x/internal/util/tls" ws_util "github.com/go-gost/x/internal/util/ws" xstats "github.com/go-gost/x/observer/stats" stats_wrapper "github.com/go-gost/x/observer/stats/wrapper" xrecorder "github.com/go-gost/x/recorder" "golang.org/x/net/http/httpguts" "golang.org/x/net/http2" "golang.org/x/time/rate" ) const ( DefaultReadTimeout = 30 * time.Second // DefaultBodySize is the default HTTP body or websocket frame size to record. DefaultBodySize = 64 * 1024 // 64KB // MaxBodySize is the maximum HTTP body or websocket frame size to record. MaxBodySize = 1024 * 1024 // 1MB // DeafultSampleRate is the default websocket sample rate (samples per second). DefaultSampleRate = 10.0 ) var ( DefaultCertPool = tls_util.NewMemoryCertPool() ) type HandleOptions struct { Dial func(ctx context.Context, network, address string) (net.Conn, error) DialTLS func(ctx context.Context, network, address string, cfg *tls.Config) (net.Conn, error) Bypass bypass.Bypass RecorderObject *xrecorder.HandlerRecorderObject Log logger.Logger } type HandleOption func(opts *HandleOptions) func WithDial(dial func(ctx context.Context, network, address string) (net.Conn, error)) HandleOption { return func(opts *HandleOptions) { opts.Dial = dial } } func WithDialTLS(dialTLS func(ctx context.Context, network, address string, cfg *tls.Config) (net.Conn, error)) HandleOption { return func(opts *HandleOptions) { opts.DialTLS = dialTLS } } func WithBypass(bypass bypass.Bypass) HandleOption { return func(opts *HandleOptions) { opts.Bypass = bypass } } func WithRecorderObject(ro *xrecorder.HandlerRecorderObject) HandleOption { return func(opts *HandleOptions) { opts.RecorderObject = ro } } func WithLog(log logger.Logger) HandleOption { return func(opts *HandleOptions) { opts.Log = log } } type Sniffer struct { Websocket bool WebsocketSampleRate float64 Recorder recorder.Recorder RecorderOptions *recorder.Options // MITM TLS termination Certificate *x509.Certificate PrivateKey crypto.PrivateKey NegotiatedProtocol string CertPool tls_util.CertPool MitmBypass bypass.Bypass ReadTimeout time.Duration } func (h *Sniffer) HandleHTTP(ctx context.Context, conn net.Conn, opts ...HandleOption) error { var ho HandleOptions for _, opt := range opts { opt(&ho) } if h.ReadTimeout <= 0 { h.ReadTimeout = DefaultReadTimeout } pStats := xstats.Stats{} conn = stats_wrapper.WrapConn(conn, &pStats) br := bufio.NewReader(conn) req, err := http.ReadRequest(br) if err != nil { return err } log := ho.Log if log.IsLevelEnabled(logger.TraceLevel) { dump, _ := httputil.DumpRequest(req, false) log.Trace(string(dump)) } ro := ho.RecorderObject ro.HTTP = &xrecorder.HTTPRecorderObject{ Host: req.Host, Proto: req.Proto, Scheme: req.URL.Scheme, Method: req.Method, URI: req.RequestURI, Request: xrecorder.HTTPRequestRecorderObject{ ContentLength: req.ContentLength, Header: req.Header.Clone(), }, } if clientIP := xhttp.GetClientIP(req); clientIP != nil { ro.ClientIP = clientIP.String() } clientAddr := ro.RemoteAddr if ro.ClientIP != "" { if _, port, _ := net.SplitHostPort(ro.RemoteAddr); port != "" { clientAddr = net.JoinHostPort(ro.ClientIP, port) } } ctx = ctxvalue.ContextWithClientAddr(ctx, ctxvalue.ClientAddr(clientAddr)) // http/2 if req.Method == "PRI" && len(req.Header) == 0 && req.URL.Path == "*" && req.Proto == "HTTP/2.0" { return h.serveH2(ctx, xnet.NewReadWriteConn(br, conn, conn), &ho) } host := req.Host if host != "" { if _, _, err := net.SplitHostPort(host); err != nil { host = net.JoinHostPort(strings.Trim(host, "[]"), "80") } ro.Host = host log = log.WithFields(map[string]any{ "host": host, }) if ho.Bypass != nil && ho.Bypass.Contains(ctx, "tcp", host) { return xbypass.ErrBypass } } dial := ho.Dial if dial == nil { dial = (&net.Dialer{}).DialContext } cc, err := dial(ctx, "tcp", host) if err != nil { return err } defer cc.Close() log = log.WithFields(map[string]any{"src": cc.LocalAddr().String(), "dst": cc.RemoteAddr().String()}) ro.Src = cc.LocalAddr().String() ro.Dst = cc.RemoteAddr().String() ro.Time = time.Time{} shouldClose, err := h.httpRoundTrip(ctx, xio.NewReadWriter(br, conn), cc, req, ro, &pStats, log) if err != nil || shouldClose { return err } for { pStats.Reset() req, err := http.ReadRequest(br) if err != nil { if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) { return nil } return err } if log.IsLevelEnabled(logger.TraceLevel) { dump, _ := httputil.DumpRequest(req, false) log.Trace(string(dump)) } if shouldClose, err := h.httpRoundTrip(ctx, xio.NewReadWriter(br, conn), cc, req, ro, &pStats, log); err != nil || shouldClose { return err } } } func (h *Sniffer) serveH2(ctx context.Context, conn net.Conn, ho *HandleOptions) error { const expectedBody = "SM\r\n\r\n" buf := make([]byte, len(expectedBody)) n, err := io.ReadFull(conn, buf) if err != nil { return fmt.Errorf("h2: error reading client preface: %s", err) } if string(buf[:n]) != expectedBody { return errors.New("h2: invalid client preface") } ro := ho.RecorderObject log := ho.Log ro.Time = time.Time{} tr := &http2.Transport{ DialTLSContext: func(ctx context.Context, network, addr string, cfg *tls.Config) (net.Conn, error) { if dial := ho.DialTLS; dial != nil { return dial(ctx, network, addr, cfg) } cc, err := (&net.Dialer{}).DialContext(ctx, network, addr) if err != nil { return nil, err } log = log.WithFields(map[string]any{"src": cc.LocalAddr().String(), "dst": cc.RemoteAddr().String()}) ro.Src = cc.LocalAddr().String() ro.Dst = cc.RemoteAddr().String() cc = tls.Client(cc, cfg) return cc, nil }, } defer tr.CloseIdleConnections() (&http2.Server{}).ServeConn(conn, &http2.ServeConnOpts{ Context: ctx, SawClientPreface: true, Handler: &h2Handler{ transport: tr, recorder: h.Recorder, recorderOptions: h.RecorderOptions, recorderObject: ro, log: log, }, }) return nil } func (h *Sniffer) httpRoundTrip(ctx context.Context, rw, cc io.ReadWriter, req *http.Request, ro *xrecorder.HandlerRecorderObject, pStats stats.Stats, log logger.Logger) (close bool, err error) { close = true ro2 := &xrecorder.HandlerRecorderObject{} *ro2 = *ro ro = ro2 ro.Time = time.Now() log.Infof("%s <-> %s", ro.RemoteAddr, req.Host) defer func() { if err != nil { ro.Err = err.Error() } ro.InputBytes = pStats.Get(stats.KindInputBytes) ro.OutputBytes = pStats.Get(stats.KindOutputBytes) ro.Duration = time.Since(ro.Time) if err := ro.Record(ctx, h.Recorder); err != nil { log.Errorf("record: %v", err) } log.WithFields(map[string]any{ "duration": time.Since(ro.Time), "inputBytes": ro.InputBytes, "outputBytes": ro.OutputBytes, }).Infof("%s >-< %s", ro.RemoteAddr, req.Host) }() ro.HTTP = &xrecorder.HTTPRecorderObject{ Host: req.Host, Proto: req.Proto, Scheme: req.URL.Scheme, Method: req.Method, URI: req.RequestURI, Request: xrecorder.HTTPRequestRecorderObject{ ContentLength: req.ContentLength, Header: req.Header.Clone(), }, } // HTTP/1.0 if req.ProtoMajor == 1 && req.ProtoMinor == 0 { if strings.ToLower(req.Header.Get("Connection")) == "keep-alive" { req.Header.Del("Connection") } else { req.Header.Set("Connection", "close") } } var reqBody *xhttp.Body if opts := h.RecorderOptions; opts != nil && opts.HTTPBody { if req.Body != nil { bodySize := opts.MaxBodySize if bodySize <= 0 { bodySize = DefaultBodySize } if bodySize > MaxBodySize { bodySize = MaxBodySize } reqBody = xhttp.NewBody(req.Body, bodySize) req.Body = reqBody } } err = req.Write(cc) if reqBody != nil { ro.HTTP.Request.Body = reqBody.Content() ro.HTTP.Request.ContentLength = reqBody.Length() } if err != nil { return } br := bufio.NewReader(cc) var resp *http.Response for { xio.SetReadDeadline(cc, time.Now().Add(h.ReadTimeout)) resp, err = http.ReadResponse(br, req) if err != nil { err = fmt.Errorf("read response: %v", err) return } if resp.StatusCode >= http.StatusContinue && resp.StatusCode < http.StatusOK { resp.Write(rw) resp.Body.Close() continue } break } defer resp.Body.Close() xio.SetReadDeadline(cc, time.Time{}) ro.HTTP.StatusCode = resp.StatusCode ro.HTTP.Response.Header = resp.Header ro.HTTP.Response.ContentLength = resp.ContentLength if log.IsLevelEnabled(logger.TraceLevel) { dump, _ := httputil.DumpResponse(resp, false) log.Trace(string(dump)) } if resp.StatusCode == http.StatusSwitchingProtocols { h.handleUpgradeResponse(ctx, rw, cc, req, resp, ro, log) return } // HTTP/1.0 if req.ProtoMajor == 1 && req.ProtoMinor == 0 { if !resp.Close { resp.Header.Set("Connection", "keep-alive") } resp.ProtoMajor = req.ProtoMajor resp.ProtoMinor = req.ProtoMinor } var respBody *xhttp.Body if opts := h.RecorderOptions; opts != nil && opts.HTTPBody { bodySize := opts.MaxBodySize if bodySize <= 0 { bodySize = DefaultBodySize } if bodySize > MaxBodySize { bodySize = MaxBodySize } respBody = xhttp.NewBody(resp.Body, bodySize) resp.Body = respBody } err = resp.Write(rw) if respBody != nil { ro.HTTP.Response.Body = respBody.Content() ro.HTTP.Response.ContentLength = respBody.Length() } if err != nil { err = fmt.Errorf("write response: %w", err) return } if resp.ContentLength >= 0 { close = resp.Close } return } func upgradeType(h http.Header) string { if !httpguts.HeaderValuesContainsToken(h["Connection"], "Upgrade") { return "" } return h.Get("Upgrade") } func (h *Sniffer) handleUpgradeResponse(ctx context.Context, rw io.ReadWriter, cc io.ReadWriter, req *http.Request, res *http.Response, ro *xrecorder.HandlerRecorderObject, log logger.Logger) error { reqUpType := upgradeType(req.Header) resUpType := upgradeType(res.Header) if !strings.EqualFold(reqUpType, resUpType) { return fmt.Errorf("backend tried to switch protocol %q when %q was requested", resUpType, reqUpType) } res.Body = nil if err := res.Write(rw); err != nil { return fmt.Errorf("response write: %v", err) } if reqUpType == "websocket" && h.Websocket { return h.sniffingWebsocketFrame(ctx, rw, cc, ro, log) } return xnet.Transport(rw, cc) } func (h *Sniffer) sniffingWebsocketFrame(ctx context.Context, rw, cc io.ReadWriter, ro *xrecorder.HandlerRecorderObject, log logger.Logger) error { errc := make(chan error, 1) sampleRate := h.WebsocketSampleRate if sampleRate == 0 { sampleRate = DefaultSampleRate } if sampleRate < 0 { sampleRate = math.MaxFloat64 } go func() { ro2 := &xrecorder.HandlerRecorderObject{} *ro2 = *ro ro := ro2 limiter := rate.NewLimiter(rate.Limit(sampleRate), int(sampleRate)) buf := &bytes.Buffer{} for { start := time.Now() if err := h.copyWebsocketFrame(cc, rw, buf, "client", ro); err != nil { errc <- err return } if limiter.Allow() { ro.Duration = time.Since(start) ro.Time = time.Now() if err := ro.Record(ctx, h.Recorder); err != nil { log.Errorf("record: %v", err) } } } }() go func() { ro2 := &xrecorder.HandlerRecorderObject{} *ro2 = *ro ro := ro2 limiter := rate.NewLimiter(rate.Limit(sampleRate), int(sampleRate)) buf := &bytes.Buffer{} for { start := time.Now() if err := h.copyWebsocketFrame(rw, cc, buf, "server", ro); err != nil { errc <- err return } if limiter.Allow() { ro.Duration = time.Since(start) ro.Time = time.Now() if err := ro.Record(ctx, h.Recorder); err != nil { log.Errorf("record: %v", err) } } } }() <-errc return nil } func (h *Sniffer) copyWebsocketFrame(w io.Writer, r io.Reader, buf *bytes.Buffer, from string, ro *xrecorder.HandlerRecorderObject) (err error) { fr := ws_util.Frame{} if _, err = fr.ReadFrom(r); err != nil { return err } ws := &xrecorder.WebsocketRecorderObject{ From: from, Fin: fr.Header.Fin, Rsv1: fr.Header.Rsv1, Rsv2: fr.Header.Rsv2, Rsv3: fr.Header.Rsv3, OpCode: int(fr.Header.OpCode), Masked: fr.Header.Masked, MaskKey: fr.Header.MaskKey, Length: fr.Header.PayloadLength, } if opts := h.RecorderOptions; opts != nil && opts.HTTPBody { bodySize := opts.MaxBodySize if bodySize <= 0 { bodySize = DefaultBodySize } if bodySize > MaxBodySize { bodySize = MaxBodySize } buf.Reset() if _, err := io.Copy(buf, io.LimitReader(fr.Data, int64(bodySize))); err != nil { return err } ws.Payload = buf.Bytes() } ro.Websocket = ws length := uint64(fr.Header.Length()) + uint64(fr.Header.PayloadLength) if from == "client" { ro.InputBytes = length ro.OutputBytes = 0 } else { ro.InputBytes = 0 ro.OutputBytes = length } fr.Data = io.MultiReader(bytes.NewReader(buf.Bytes()), fr.Data) if _, err := fr.WriteTo(w); err != nil { return err } return nil } func (h *Sniffer) HandleTLS(ctx context.Context, conn net.Conn, opts ...HandleOption) error { var ho HandleOptions for _, opt := range opts { opt(&ho) } if h.ReadTimeout <= 0 { h.ReadTimeout = DefaultReadTimeout } buf := new(bytes.Buffer) clientHello, err := dissector.ParseClientHello(io.TeeReader(conn, buf)) if err != nil { return err } log := ho.Log ro := ho.RecorderObject ro.TLS = &xrecorder.TLSRecorderObject{ ServerName: clientHello.ServerName, ClientHello: hex.EncodeToString(buf.Bytes()), } if len(clientHello.SupportedProtos) > 0 { ro.TLS.Proto = clientHello.SupportedProtos[0] } ctx = ctxvalue.ContextWithClientAddr(ctx, ctxvalue.ClientAddr(ro.RemoteAddr)) host := clientHello.ServerName if host != "" { if _, _, err := net.SplitHostPort(host); err != nil { host = net.JoinHostPort(strings.Trim(host, "[]"), "443") } ro.Host = host if ho.Bypass != nil && ho.Bypass.Contains(ctx, "tcp", host) { return xbypass.ErrBypass } } dial := ho.Dial if dial == nil { dial = (&net.Dialer{}).DialContext } cc, err := dial(ctx, "tcp", host) if err != nil { return err } defer cc.Close() log = log.WithFields(map[string]any{"src": cc.LocalAddr().String(), "dst": cc.RemoteAddr().String()}) ro.Src = cc.LocalAddr().String() ro.Dst = cc.RemoteAddr().String() if h.Certificate != nil && h.PrivateKey != nil && len(clientHello.SupportedProtos) > 0 && (clientHello.SupportedProtos[0] == "h2" || clientHello.SupportedProtos[0] == "http/1.1") { if host == "" { host = ro.Host } if h.MitmBypass == nil || !h.MitmBypass.Contains(ctx, "tcp", host) { return h.terminateTLS(ctx, xnet.NewReadWriteConn(io.MultiReader(buf, conn), conn, conn), cc, clientHello, &ho) } } if _, err := buf.WriteTo(cc); err != nil { return err } xio.SetReadDeadline(cc, time.Now().Add(h.ReadTimeout)) serverHello, err := dissector.ParseServerHello(io.TeeReader(cc, buf)) xio.SetReadDeadline(cc, time.Time{}) if serverHello != nil { ro.TLS.CipherSuite = tls_util.CipherSuite(serverHello.CipherSuite).String() ro.TLS.CompressionMethod = serverHello.CompressionMethod if serverHello.Proto != "" { ro.TLS.Proto = serverHello.Proto } if serverHello.Version > 0 { ro.TLS.Version = tls_util.Version(serverHello.Version).String() } } if buf.Len() > 0 { ro.TLS.ServerHello = hex.EncodeToString(buf.Bytes()) } if _, err := buf.WriteTo(conn); err != nil { return err } log.Infof("%s <-> %s", ro.RemoteAddr, ro.Host) xnet.Transport(conn, cc) log.WithFields(map[string]any{ "duration": time.Since(ro.Time), }).Infof("%s >-< %s", ro.RemoteAddr, ro.Host) return err } func (h *Sniffer) terminateTLS(ctx context.Context, conn, cc net.Conn, clientHello *dissector.ClientHelloInfo, ho *HandleOptions) error { ro := ho.RecorderObject log := ho.Log nextProtos := clientHello.SupportedProtos if h.NegotiatedProtocol != "" { nextProtos = []string{h.NegotiatedProtocol} } cfg := &tls.Config{ ServerName: clientHello.ServerName, NextProtos: nextProtos, CipherSuites: clientHello.CipherSuites, } if cfg.ServerName == "" { cfg.InsecureSkipVerify = true } clientConn := tls.Client(cc, cfg) if err := clientConn.HandshakeContext(ctx); err != nil { return err } cs := clientConn.ConnectionState() ro.TLS.CipherSuite = tls_util.CipherSuite(cs.CipherSuite).String() ro.TLS.Proto = cs.NegotiatedProtocol ro.TLS.Version = tls_util.Version(cs.Version).String() host := cfg.ServerName if host == "" { if host = cs.PeerCertificates[0].Subject.CommonName; host == "" { host = ro.Host } } if h, _, _ := net.SplitHostPort(host); h != "" { host = h } negotiatedProtocol := cs.NegotiatedProtocol if h.NegotiatedProtocol != "" { negotiatedProtocol = h.NegotiatedProtocol } nextProtos = nil if negotiatedProtocol != "" { nextProtos = []string{negotiatedProtocol} } // cache the tls server handshake record. wb := &bytes.Buffer{} conn = xnet.NewReadWriteConn(conn, io.MultiWriter(wb, conn), conn) serverConn := tls.Server(conn, &tls.Config{ NextProtos: nextProtos, GetCertificate: func(chi *tls.ClientHelloInfo) (*tls.Certificate, error) { certPool := h.CertPool if certPool == nil { certPool = DefaultCertPool } serverName := chi.ServerName if serverName == "" { serverName = host } cert, err := certPool.Get(serverName) if cert != nil { pool := x509.NewCertPool() pool.AddCert(h.Certificate) if _, err = cert.Verify(x509.VerifyOptions{ DNSName: serverName, Roots: pool, }); err != nil { log.Warnf("verify cached certificate for %s: %v", serverName, err) cert = nil } } if cert == nil { cert, err = tls_util.GenerateCertificate(serverName, 7*24*time.Hour, h.Certificate, h.PrivateKey) certPool.Put(serverName, cert) } if err != nil { return nil, err } return &tls.Certificate{ Certificate: [][]byte{cert.Raw}, PrivateKey: h.PrivateKey, }, nil }, }) err := serverConn.HandshakeContext(ctx) if record, _ := dissector.ReadRecord(wb); record != nil { wb.Reset() record.WriteTo(wb) ro.TLS.ServerHello = hex.EncodeToString(wb.Bytes()) } if err != nil { return err } opts := []HandleOption{ WithDial(func(ctx context.Context, network, address string) (net.Conn, error) { return clientConn, nil }), WithDialTLS(func(ctx context.Context, network, address string, cfg *tls.Config) (net.Conn, error) { return clientConn, nil }), WithRecorderObject(ro), WithLog(log), } return h.HandleHTTP(ctx, serverConn, opts...) } type h2Handler struct { transport http.RoundTripper recorder recorder.Recorder recorderOptions *recorder.Options recorderObject *xrecorder.HandlerRecorderObject log logger.Logger } func (h *h2Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) { log := h.log ro := &xrecorder.HandlerRecorderObject{} *ro = *h.recorderObject ro.Time = time.Now() var err error log.Infof("%s <-> %s", ro.RemoteAddr, r.Host) defer func() { ro.Duration = time.Since(ro.Time) if err != nil { ro.Err = err.Error() } if err := ro.Record(r.Context(), h.recorder); err != nil { log.Errorf("record: %v", err) } log.WithFields(map[string]any{ "duration": time.Since(ro.Time), }).Infof("%s >-< %s", ro.RemoteAddr, r.Host) }() if clientIP := xhttp.GetClientIP(r); clientIP != nil { ro.ClientIP = clientIP.String() } ro.HTTP = &xrecorder.HTTPRecorderObject{ Host: r.Host, Proto: r.Proto, Scheme: "https", Method: r.Method, URI: r.RequestURI, Request: xrecorder.HTTPRequestRecorderObject{ ContentLength: r.ContentLength, Header: r.Header.Clone(), }, } if log.IsLevelEnabled(logger.TraceLevel) { dump, _ := httputil.DumpRequest(r, false) log.Trace(string(dump)) } url := r.URL url.Scheme = "https" url.Host = r.Host req := &http.Request{ Method: r.Method, URL: url, Host: r.Host, Header: r.Header, Body: r.Body, ContentLength: r.ContentLength, Trailer: r.Trailer, } var reqBody *xhttp.Body if opts := h.recorderOptions; opts != nil && opts.HTTPBody { if req.Body != nil { bodySize := opts.MaxBodySize if bodySize <= 0 { bodySize = DefaultBodySize } if bodySize > MaxBodySize { bodySize = MaxBodySize } reqBody = xhttp.NewBody(req.Body, bodySize) req.Body = reqBody } } resp, err := h.transport.RoundTrip(req.WithContext(r.Context())) if reqBody != nil { ro.HTTP.Request.Body = reqBody.Content() ro.HTTP.Request.ContentLength = reqBody.Length() } if err != nil { log.Error(err) w.WriteHeader(http.StatusServiceUnavailable) return } defer resp.Body.Close() ro.HTTP.StatusCode = resp.StatusCode ro.HTTP.Response.Header = resp.Header ro.HTTP.Response.ContentLength = resp.ContentLength if log.IsLevelEnabled(logger.TraceLevel) { dump, _ := httputil.DumpResponse(resp, false) log.Trace(string(dump)) } h.setHeader(w, resp.Header) w.WriteHeader(resp.StatusCode) var respBody *xhttp.Body if opts := h.recorderOptions; opts != nil && opts.HTTPBody { bodySize := opts.MaxBodySize if bodySize <= 0 { bodySize = DefaultBodySize } if bodySize > MaxBodySize { bodySize = MaxBodySize } respBody = xhttp.NewBody(resp.Body, bodySize) resp.Body = respBody } io.Copy(w, resp.Body) if respBody != nil { ro.HTTP.Response.Body = respBody.Content() ro.HTTP.Response.ContentLength = respBody.Length() } } func (h *h2Handler) setHeader(w http.ResponseWriter, header http.Header) { for k, v := range header { for i := range v { w.Header().Add(k, v[i]) } } }