Init

.gitignore

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+smoothie
+.ssh

go.mod

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+module smoothie
+
+go 1.16
+
+replace github.com/charmbracelet/charm => ../charm
+
+require (
+	github.com/charmbracelet/bubbletea v0.14.0
+	github.com/charmbracelet/charm v0.8.6
+	github.com/charmbracelet/lipgloss v0.2.1
+	github.com/gliderlabs/ssh v0.3.3
+	github.com/meowgorithm/babyenv v1.3.0
+	golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97
+)

main.go

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+package main
+
+import (
+	"smoothie/tui"
+
+	"github.com/meowgorithm/babyenv"
+)
+
+type Config struct {
+	KeyPath string `env:"SMOOTHIE_KEY_PATH" default:".ssh/smoothie_server_ed25519"`
+	Port    int    `env:"SMOOTHIE_PORT" default:"23231"`
+}
+
+func main() {
+	var cfg Config
+	err := babyenv.Parse(&cfg)
+	if err != nil {
+		panic(err)
+	}
+	s, err := NewServer(cfg.Port, cfg.KeyPath, tui.SessionHandler)
+	if err != nil {
+		panic(err)
+	}
+	err = s.Start()
+	if err != nil {
+		panic(err)
+	}
+}

server.go

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+package main
+
+import (
+	"fmt"
+	"log"
+	"path/filepath"
+	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/charm/keygen"
+	"github.com/gliderlabs/ssh"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+type SessionHandler func(ssh.Session) (tea.Model, error)
+
+type Server struct {
+	server  *ssh.Server
+	key     gossh.PublicKey
+	handler SessionHandler
+}
+
+func NewServer(port int, keyPath string, handler SessionHandler) (*Server, error) {
+	s := &Server{
+		server:  &ssh.Server{},
+		handler: handler,
+	}
+	s.server.Version = "OpenSSH_7.6p1"
+	s.server.Addr = fmt.Sprintf(":%d", port)
+	s.server.Handler = s.sessionHandler
+	s.server.PasswordHandler = s.passHandler
+	s.server.PublicKeyHandler = s.authHandler
+	kps := strings.Split(keyPath, string(filepath.Separator))
+	kp := strings.Join(kps[:len(kps)-1], string(filepath.Separator))
+	n := strings.TrimRight(kps[len(kps)-1], "_ed25519")
+	_, err := keygen.NewSSHKeyPair(kp, n, nil, "ed25519")
+	if err != nil {
+		return nil, err
+	}
+	k := ssh.HostKeyFile(keyPath)
+	err = s.server.SetOption(k)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+func (srv *Server) sessionHandler(s ssh.Session) {
+	hpk := s.PublicKey() != nil
+	log.Printf("%s connect %v %v\n", s.RemoteAddr().String(), hpk, s.Command())
+	m, err := srv.handler(s)
+	if err != nil {
+		log.Printf("%s error %v %s\n", s.RemoteAddr().String(), hpk, err)
+		s.Exit(1)
+		return
+	}
+	if m != nil {
+		p := tea.NewProgram(m, tea.WithInput(s), tea.WithOutput(s))
+		err = p.Start()
+		if err != nil {
+			log.Printf("%s error %v %s\n", s.RemoteAddr().String(), hpk, err)
+			s.Exit(1)
+			return
+		}
+	}
+	log.Printf("%s disconnect %v %v\n", s.RemoteAddr().String(), hpk, s.Command())
+}
+
+func (srv *Server) authHandler(ctx ssh.Context, key ssh.PublicKey) bool {
+	return true
+}
+
+func (srv *Server) passHandler(ctx ssh.Context, pass string) bool {
+	return true
+}
+
+func (srv *Server) Start() error {
+	return srv.server.ListenAndServe()
+}

tui/commands.go

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+package tui
+
+import (
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+type windowMsg struct{}
+
+func (m *Model) windowChangesCmd() tea.Msg {
+	w := <-m.windowChanges
+	m.width = w.Width
+	m.height = w.Height
+	return windowMsg{}
+}

tui/model.go

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+package tui
+
+import (
+	"fmt"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/gliderlabs/ssh"
+)
+
+type sessionState int
+
+const (
+	startState sessionState = iota
+	errorState
+	quittingState
+	quitState
+)
+
+type stateMsg struct{ state sessionState }
+type infoMsg struct{ text string }
+type errMsg struct{ err error }
+
+func (e errMsg) Error() string {
+	return e.err.Error()
+}
+
+func SessionHandler(s ssh.Session) (tea.Model, error) {
+	pty, changes, active := s.Pty()
+	if !active {
+		return nil, fmt.Errorf("you need to do this from a terminal with PTY support")
+	}
+	return NewModel(pty.Window.Width, pty.Window.Height, changes), nil
+}
+
+type Model struct {
+	state         sessionState
+	error         string
+	info          string
+	width         int
+	height        int
+	windowChanges <-chan ssh.Window
+}
+
+func NewModel(width int, height int, windowChanges <-chan ssh.Window) *Model {
+	m := &Model{
+		width:         width,
+		height:        height,
+		windowChanges: windowChanges,
+	}
+	m.state = startState
+	return m
+}
+
+func (m *Model) Init() tea.Cmd {
+	return tea.Batch(m.windowChangesCmd, tea.HideCursor)
+}
+
+func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	cmds := make([]tea.Cmd, 0)
+	// Always allow state, error, info, window resize and quit messages
+	switch msg := msg.(type) {
+	case stateMsg:
+		m.state = msg.state
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "q", "ctrl+c":
+			return m, tea.Quit
+		}
+	case errMsg:
+		m.error = msg.Error()
+		m.state = errorState
+		return m, nil
+	case infoMsg:
+		m.info = msg.text
+	case windowMsg:
+		cmds = append(cmds, m.windowChangesCmd)
+	case tea.WindowSizeMsg:
+		m.width = msg.Width
+		m.height = msg.Height
+	}
+	return m, tea.Batch(cmds...)
+}
+
+func (m *Model) View() string {
+	pad := 6
+	h := headerStyle.Width(m.width - pad).Render("Smoothie")
+	f := footerStyle.Render(m.info)
+	s := ""
+	content := ""
+	switch m.state {
+	case errorState:
+		s += errorStyle.Render(fmt.Sprintf("Bummer: %s", m.error))
+	default:
+		s = normalStyle.Render(fmt.Sprintf("Doing something weird %d", m.state))
+	}
+	content = h + "\n" + s + "\n" + f
+	return appBoxStyle.Render(content)
+}

tui/style.go

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+package tui
+
+import (
+	"github.com/charmbracelet/lipgloss"
+)
+
+var appBoxStyle = lipgloss.NewStyle().
+	PaddingLeft(2).
+	PaddingRight(2).
+	MarginBottom(1)
+
+var headerStyle = lipgloss.NewStyle().
+	Foreground(lipgloss.Color("#670083")).
+	Align(lipgloss.Right).
+	Bold(true)
+
+var normalStyle = lipgloss.NewStyle().
+	Foreground(lipgloss.Color("#FFFFFF"))
+
+var footerStyle = lipgloss.NewStyle().
+	BorderStyle(lipgloss.Border{Left: ">"}).
+	BorderForeground(lipgloss.Color("#6D6D6D")).
+	BorderLeft(true).
+	Foreground(lipgloss.Color("#373737")).
+	PaddingLeft(1).
+	MarginLeft(1).
+	Bold(true)
+
+var errorStyle = lipgloss.NewStyle().
+	Foreground(lipgloss.Color("#FF00000"))