ginuerzh
356 lines
8.6 KiB
Go
356 lines
8.6 KiB
Go
package ssh
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import (
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"bufio"
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"bytes"
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"context"
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"crypto/tls"
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"encoding/binary"
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"errors"
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"fmt"
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"net"
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"strconv"
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"time"
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"github.com/go-gost/core/handler"
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"github.com/go-gost/core/logger"
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md "github.com/go-gost/core/metadata"
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"github.com/go-gost/core/recorder"
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xbypass "github.com/go-gost/x/bypass"
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ctxvalue "github.com/go-gost/x/ctx"
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xnet "github.com/go-gost/x/internal/net"
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"github.com/go-gost/x/internal/util/sniffing"
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sshd_util "github.com/go-gost/x/internal/util/sshd"
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tls_util "github.com/go-gost/x/internal/util/tls"
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rate_limiter "github.com/go-gost/x/limiter/rate"
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xrecorder "github.com/go-gost/x/recorder"
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"github.com/go-gost/x/registry"
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"golang.org/x/crypto/ssh"
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)
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// Applicable SSH Request types for Port Forwarding - RFC 4254 7.X
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const (
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ForwardedTCPReturnRequest = "forwarded-tcpip" // RFC 4254 7.2
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)
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func init() {
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registry.HandlerRegistry().Register("sshd", NewHandler)
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}
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type forwardHandler struct {
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md metadata
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options handler.Options
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recorder recorder.RecorderObject
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certPool tls_util.CertPool
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}
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func NewHandler(opts ...handler.Option) handler.Handler {
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options := handler.Options{}
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for _, opt := range opts {
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opt(&options)
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}
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return &forwardHandler{
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options: options,
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}
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}
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func (h *forwardHandler) Init(md md.Metadata) (err error) {
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if err = h.parseMetadata(md); err != nil {
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return
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}
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for _, ro := range h.options.Recorders {
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if ro.Record == xrecorder.RecorderServiceHandler {
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h.recorder = ro
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break
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}
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}
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if h.md.certificate != nil && h.md.privateKey != nil {
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h.certPool = tls_util.NewMemoryCertPool()
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}
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return nil
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}
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func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) (err error) {
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defer conn.Close()
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start := time.Now()
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ro := &xrecorder.HandlerRecorderObject{
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Service: h.options.Service,
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Network: "tcp",
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RemoteAddr: conn.RemoteAddr().String(),
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LocalAddr: conn.LocalAddr().String(),
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Time: start,
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SID: string(ctxvalue.SidFromContext(ctx)),
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}
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ro.ClientIP, _, _ = net.SplitHostPort(conn.RemoteAddr().String())
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log := h.options.Logger.WithFields(map[string]any{
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"remote": conn.RemoteAddr().String(),
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"local": conn.LocalAddr().String(),
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"sid": ctxvalue.SidFromContext(ctx),
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})
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log.Infof("%s <> %s", conn.RemoteAddr(), conn.LocalAddr())
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defer func() {
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if err != nil {
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ro.Err = err.Error()
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}
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ro.Duration = time.Since(start)
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ro.Record(ctx, h.recorder.Recorder)
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log.WithFields(map[string]any{
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"duration": time.Since(start),
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}).Infof("%s >< %s", conn.RemoteAddr(), conn.LocalAddr())
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}()
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if !h.checkRateLimit(conn.RemoteAddr()) {
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return rate_limiter.ErrRateLimit
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}
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switch cc := conn.(type) {
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case *sshd_util.DirectForwardConn:
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return h.handleDirectForward(ctx, cc, ro, log)
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case *sshd_util.RemoteForwardConn:
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return h.handleRemoteForward(ctx, cc, ro, log)
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default:
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err := errors.New("sshd: wrong connection type")
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log.Error(err)
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return err
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}
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}
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func (h *forwardHandler) handleDirectForward(ctx context.Context, conn *sshd_util.DirectForwardConn, ro *xrecorder.HandlerRecorderObject, log logger.Logger) error {
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targetAddr := conn.DstAddr()
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ro.Host = targetAddr
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log = log.WithFields(map[string]any{
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"dst": fmt.Sprintf("%s/%s", targetAddr, "tcp"),
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"cmd": "connect",
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})
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log.Debugf("%s >> %s", conn.RemoteAddr(), targetAddr)
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if h.options.Bypass != nil && h.options.Bypass.Contains(ctx, "tcp", targetAddr) {
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log.Debugf("bypass %s", targetAddr)
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return xbypass.ErrBypass
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}
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var buf bytes.Buffer
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cc, err := h.options.Router.Dial(ctxvalue.ContextWithBuffer(ctx, &buf), "tcp", targetAddr)
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ro.Route = buf.String()
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if err != nil {
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return err
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}
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defer cc.Close()
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if h.md.sniffing {
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if h.md.sniffingTimeout > 0 {
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conn.SetReadDeadline(time.Now().Add(h.md.sniffingTimeout))
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}
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br := bufio.NewReader(conn)
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proto, _ := sniffing.Sniff(ctx, br)
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ro.Proto = proto
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if h.md.sniffingTimeout > 0 {
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conn.SetReadDeadline(time.Time{})
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}
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dial := func(ctx context.Context, network, address string) (net.Conn, error) {
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return cc, nil
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}
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dialTLS := func(ctx context.Context, network, address string, cfg *tls.Config) (net.Conn, error) {
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return cc, nil
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}
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sniffer := &sniffing.Sniffer{
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Recorder: h.recorder.Recorder,
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RecorderOptions: h.recorder.Options,
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Certificate: h.md.certificate,
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PrivateKey: h.md.privateKey,
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NegotiatedProtocol: h.md.alpn,
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CertPool: h.certPool,
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MitmBypass: h.md.mitmBypass,
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ReadTimeout: h.md.readTimeout,
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}
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switch proto {
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case sniffing.ProtoHTTP:
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return sniffer.HandleHTTP(ctx, xnet.NewReadWriteConn(br, conn, conn),
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sniffing.WithDial(dial),
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sniffing.WithDialTLS(dialTLS),
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sniffing.WithRecorderObject(ro),
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sniffing.WithLog(log),
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)
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case sniffing.ProtoTLS:
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return sniffer.HandleTLS(ctx, xnet.NewReadWriteConn(br, conn, conn),
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sniffing.WithDial(dial),
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sniffing.WithDialTLS(dialTLS),
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sniffing.WithRecorderObject(ro),
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sniffing.WithLog(log),
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)
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}
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}
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t := time.Now()
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log.Infof("%s <-> %s", cc.LocalAddr(), targetAddr)
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xnet.Transport(conn, cc)
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log.WithFields(map[string]any{
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"duration": time.Since(t),
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}).Infof("%s >-< %s", cc.LocalAddr(), targetAddr)
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return nil
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}
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func (h *forwardHandler) handleRemoteForward(ctx context.Context, conn *sshd_util.RemoteForwardConn, ro *xrecorder.HandlerRecorderObject, log logger.Logger) error {
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req := conn.Request()
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t := tcpipForward{}
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if err := ssh.Unmarshal(req.Payload, &t); err != nil {
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log.Error(err)
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return err
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}
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network := "tcp"
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addr := net.JoinHostPort(t.Host, strconv.Itoa(int(t.Port)))
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ro.Host = addr
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log = log.WithFields(map[string]any{
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"dst": fmt.Sprintf("%s/%s", addr, network),
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"cmd": "bind",
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})
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log.Debugf("%s >> %s", conn.RemoteAddr(), addr)
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// tie to the client connection
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ln, err := net.Listen(network, addr)
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if err != nil {
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log.Error(err)
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req.Reply(false, nil)
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return err
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}
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defer ln.Close()
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log = log.WithFields(map[string]any{
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"bind": fmt.Sprintf("%s/%s", ln.Addr(), ln.Addr().Network()),
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})
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log.Debugf("bind on %s OK", ln.Addr())
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err = func() error {
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if t.Port == 0 && req.WantReply { // Client sent port 0. let them know which port is actually being used
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_, port, err := getHostPortFromAddr(ln.Addr())
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if err != nil {
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return err
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}
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var b [4]byte
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binary.BigEndian.PutUint32(b[:], uint32(port))
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t.Port = uint32(port)
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return req.Reply(true, b[:])
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}
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return req.Reply(true, nil)
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}()
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if err != nil {
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log.Error(err)
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return err
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}
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sshConn := conn.Conn()
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go func() {
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for {
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cc, err := ln.Accept()
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if err != nil { // Unable to accept new connection - listener is likely closed
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return
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}
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go func(conn net.Conn) {
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defer conn.Close()
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log := log.WithFields(map[string]any{
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"local": conn.LocalAddr().String(),
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"remote": conn.RemoteAddr().String(),
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})
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p := directForward{}
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var err error
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var portnum int
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p.Host1 = t.Host
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p.Port1 = t.Port
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p.Host2, portnum, err = getHostPortFromAddr(conn.RemoteAddr())
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if err != nil {
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return
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}
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p.Port2 = uint32(portnum)
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ch, reqs, err := sshConn.OpenChannel(ForwardedTCPReturnRequest, ssh.Marshal(p))
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if err != nil {
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log.Error("open forwarded channel: ", err)
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return
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}
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defer ch.Close()
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go ssh.DiscardRequests(reqs)
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t := time.Now()
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log.Debugf("%s <-> %s", conn.LocalAddr(), conn.RemoteAddr())
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xnet.Transport(ch, conn)
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log.WithFields(map[string]any{
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"duration": time.Since(t),
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}).Debugf("%s >-< %s", conn.LocalAddr(), conn.RemoteAddr())
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}(cc)
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}
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}()
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tm := time.Now()
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log.Infof("%s <-> %s", conn.RemoteAddr(), addr)
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<-conn.Done()
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log.WithFields(map[string]any{
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"duration": time.Since(tm),
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}).Infof("%s >-< %s", conn.RemoteAddr(), addr)
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return nil
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}
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func (h *forwardHandler) checkRateLimit(addr net.Addr) bool {
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if h.options.RateLimiter == nil {
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return true
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}
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host, _, _ := net.SplitHostPort(addr.String())
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if limiter := h.options.RateLimiter.Limiter(host); limiter != nil {
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return limiter.Allow(1)
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}
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return true
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}
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func getHostPortFromAddr(addr net.Addr) (host string, port int, err error) {
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host, portString, err := net.SplitHostPort(addr.String())
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if err != nil {
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return
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}
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port, err = strconv.Atoi(portString)
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return
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}
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// directForward is structure for RFC 4254 7.2 - can be used for "forwarded-tcpip" and "direct-tcpip"
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type directForward struct {
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Host1 string
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Port1 uint32
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Host2 string
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Port2 uint32
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}
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func (p directForward) String() string {
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return fmt.Sprintf("%s:%d -> %s:%d", p.Host2, p.Port2, p.Host1, p.Port1)
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}
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// tcpipForward is structure for RFC 4254 7.1 "tcpip-forward" request
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type tcpipForward struct {
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Host string
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Port uint32
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}
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