func()

in pkg/sshd/tcpip.go [118:221]
94 lines of code
16 McCabe index (conditional complexity)

func (h *ForwardedTCPHandler) HandleSSHRequest(ctx context.Context, srv *Server, req *gossh.Request, conn *gossh.ServerConn) (bool, []byte) {
	h.Lock()
	if h.forwards == nil {
		h.forwards = make(map[string]net.Listener)
	}
	h.Unlock()
	switch req.Type {
	case "tcpip-forward":
		var reqPayload remoteForwardRequest
		if err := gossh.Unmarshal(req.Payload, &reqPayload); err != nil {
			// TODO: log parse failure
			return false, []byte{}
		}
		//if srv.ReversePortForwardingCallback == nil || !srv.ReversePortForwardingCallback(ctx, reqPayload.BindAddr, reqPayload.BindPort) {
		//	return false, []byte("port forwarding is disabled")
		//}
		addr := net.JoinHostPort(reqPayload.BindAddr, strconv.Itoa(int(reqPayload.BindPort)))
		ln, err := net.Listen("tcp", addr)
		if err != nil {
			// TODO: log listen failure
			return false, []byte{}
		}
		_, destPortStr, _ := net.SplitHostPort(ln.Addr().String())
		destPort, err := strconv.Atoi(destPortStr)
		if err != nil || destPort >= 2 ^ 32 {
			return false, []byte{}
		}
		h.Lock()
		h.forwards[addr] = ln
		h.Unlock()
		go func() {
			<-ctx.Done()
			h.Lock()
			ln, ok := h.forwards[addr]
			h.Unlock()
			if ok {
				ln.Close()
			}
		}()
		go func() {
			for {
				c, err := ln.Accept()
				if err != nil {
					// TODO: log accept failure
					break
				}
				originAddr, orignPortStr, _ := net.SplitHostPort(c.RemoteAddr().String())
				originPort, err := strconv.Atoi(orignPortStr)
				if err != nil || originPort >= 2 ^ 32 {
					c.Close()
					continue
				}

				payload := gossh.Marshal(&remoteForwardChannelData{
					DestAddr:   reqPayload.BindAddr,
					DestPort:   uint32(destPort),
					OriginAddr: originAddr,
					OriginPort: uint32(originPort),
				})
				go func() {
					ch, reqs, err := conn.OpenChannel(forwardedTCPChannelType, payload)
					if err != nil {
						// TODO: log failure to open channel
						log.Println(err)
						c.Close()
						return
					}
					go gossh.DiscardRequests(reqs)
					go func() {
						defer ch.Close()
						defer c.Close()
						io.Copy(ch, c)
					}()
					go func() {
						defer ch.Close()
						defer c.Close()
						io.Copy(c, ch)
					}()
				}()
			}
			h.Lock()
			delete(h.forwards, addr)
			h.Unlock()
		}()
		return true, gossh.Marshal(&remoteForwardSuccess{uint32(destPort)})

	case "cancel-tcpip-forward":
		var reqPayload remoteForwardCancelRequest
		if err := gossh.Unmarshal(req.Payload, &reqPayload); err != nil {
			// TODO: log parse failure
			return false, []byte{}
		}
		addr := net.JoinHostPort(reqPayload.BindAddr, strconv.Itoa(int(reqPayload.BindPort)))
		h.Lock()
		ln, ok := h.forwards[addr]
		h.Unlock()
		if ok {
			ln.Close()
		}
		return true, nil
	default:
		return false, nil
	}
}