Polishing, fix deadlock

bot/bot.go

@@ -27,9 +27,10 @@ const (
 		"the main `channel`, or in `split` mode, use the respective keywords (default: `%s`). To define the terminal size, use the words " +
 		"`tiny`, `small`, `medium` or `large` (default: `%s`). Use `full` or `trim` to set the window mode (default: `%s`), and `everyone` " +
 		"or `only-me` to define who can send commands (default: `%s`). Send `record` or `norecord` to define if your session should be " +
-		"recorded (default: `%s`). To start a private REPL session, just DM me."
+		"recorded (default: `%s`)."
 	shareMessage = "Using the word `share` will allow you to share your own terminal here in the chat. Terminal sharing " +
 		"sessions are always started in `only-me` mode, unless overridden."
+	webMessage                      = "Use the word `web` or `noweb` to enable a web-based terminal for this session (default: `%s`)."
 	unknownCommandMessage           = "I am not quite sure what you mean by _%s_ ⁉"
 	misconfiguredMessage            = "😭 Oh no. It looks like REPLbot is misconfigured. I couldn't find any scripts to run."
 	maxTotalSessionsExceededMessage = "😭 There are too many active sessions. Please wait until another session is closed."
@@ -137,6 +138,9 @@ func (b *Bot) Stop() {
 		if sess.conf.share != nil {
 			delete(b.shareUser, sess.conf.share.user)
 		}
+		if sess.webPrefix != "" {
+			delete(b.webPrefix, sess.webPrefix)
+		}
 	}
 	b.cancelFn() // This must be at the end, see app.go
 }
@@ -228,8 +232,6 @@ func (b *Bot) parseSessionConfig(ev *messageEvent) (*sessionConfig, error) {
 			conf.size = config.Sizes[field]
 		case recordCommand, noRecordCommand:
 			conf.record = field == recordCommand
-		case webCommand, noWebCommand:
-			conf.web = field == webCommand
 		default:
 			if b.config.ShareEnabled() && field == shareCommand {
 				relayPort, err := util.RandomPort()
@@ -251,6 +253,8 @@ func (b *Bot) parseSessionConfig(ev *messageEvent) (*sessionConfig, error) {
 					hostKeyPair:   hostKeyPair,
 					clientKeyPair: clientKeyPair,
 				}
+			} else if b.config.WebHost != "" && (field == webCommand || field == noWebCommand) {
+				conf.web = field == webCommand
 			} else if s := b.config.Script(field); conf.script == "" && s != "" {
 				conf.script = s
 			} else {
@@ -353,6 +357,9 @@ func (b *Bot) startSession(conf *sessionConfig) error {
 		if conf.share != nil {
 			delete(b.shareUser, conf.share.user)
 		}
+		if sess.webPrefix != "" {
+			delete(b.webPrefix, sess.webPrefix)
+		}
 		b.mu.Unlock()
 	}()
 	return nil
@@ -370,6 +377,13 @@ func (b *Bot) handleHelp(channel, thread string, err error) error {
 	} else {
 		messageTemplate = err.Error() + "\n\n" + mentionMessage
 	}
+	if b.config.WebHost != "" {
+		defaultWebCommand := webCommand
+		if !b.config.DefaultWeb {
+			defaultWebCommand = noWebCommand
+		}
+		messageTemplate += " " + fmt.Sprintf(webMessage, defaultWebCommand)
+	}
 	if b.config.ShareEnabled() {
 		messageTemplate += "\n\n" + shareMessage
 		scripts = append(scripts, shareCommand)
@@ -413,24 +427,25 @@ func (b *Bot) webHandler(w http.ResponseWriter, r *http.Request) {
 
 func (b *Bot) webHandlerInternal(w http.ResponseWriter, r *http.Request) error {
 	parts := strings.Split(r.URL.Path, "/")
-	if len(parts) < 3 { // must be /prefix/, not just /prefix
+	if len(parts) < 2 {
 		return errors.New("invalid prefix")
 	}
 	prefix := parts[1]
 	b.mu.RLock()
+	var webPort int
 	session := b.webPrefix[prefix]
+	if session != nil {
+		webPort = session.webPort
+	}
 	b.mu.RUnlock()
-	if session == nil {
+	if session == nil || webPort == 0 {
 		return errors.New("session not found")
 	}
-	b.mu.RLock()
-	webPort := session.webPort
-	if webPort == 0 {
-		return errors.New("no active web session")
+	if len(parts) < 3 { // must be /prefix/, not just /prefix
+		http.Redirect(w, r, r.URL.String()+"/", http.StatusTemporaryRedirect)
+		return nil
 	}
-	b.mu.RUnlock()
 	proxy := &httputil.ReverseProxy{Director: func(r *http.Request) {
-		log.Printf("[%s] proxying web request: %s", session.conf.id, r.URL.Path)
 		r.URL.Scheme = "http"
 		r.URL.Host = fmt.Sprintf("127.0.0.1:%d", webPort)
 		r.URL.Path = strings.TrimPrefix(r.URL.Path, "/"+prefix)

bot/session.go

@@ -47,8 +47,8 @@ const (
 	cannotAddOwnerToDenyList            = "🙁 I don't think adding the session owner to the deny list is a good idea. I must protest."
 	recordingTooLargeMessage            = "🙁 I'm sorry, but you've produced too much output in this session. You may want to run a session with `norecord` to avoid this problem."
 	shareStartCommandMessage            = "To start your terminal sharing session, please run the following command from your terminal:\n\n```bash -c \"$(ssh -T -p %s %s@%s $USER)\"```"
-	sessionWithWebStartReadOnlyMessage  = "You can also view the session via http://%s/%s/. Use `!web rw` to switch the web terminal to read-write mode, or `!web off` to turn if off."
-	sessionWithWebStartReadWriteMessage = "You can also view *and control* the session via http://%s/%s/. Use `!web ro` to switch the web terminal to read-only mode, or `!web off` to turn if off."
+	sessionWithWebStartReadOnlyMessage  = "You can also view the session via http://%s/%s. Use `!web rw` to switch the web terminal to read-write mode, or `!web off` to turn if off."
+	sessionWithWebStartReadWriteMessage = "You can also view *and control* the session via http://%s/%s. Use `!web ro` to switch the web terminal to read-only mode, or `!web off` to turn if off."
 	allowCommandHelpMessage             = "To allow other users to interact with this session, use the `!allow` command like so: !allow %s\n\nYou may tag multiple users, or use the words " +
 		"`everyone`/`all` to allow all users, or `nobody`/`only-me` to only yourself access."
 	denyCommandHelpMessage = "To deny users from interacting with this session, use the `!deny` command like so: !deny %s\n\nYou may tag multiple users, or use the words " +
@@ -64,10 +64,11 @@ const (
 	webStoppedMessage       = "👍 Okay, I stopped the web terminal."
 	webIsReadOnlyMessage    = "The terminal is *read-only*. Use `!web rw` to change it to read-write, and `!web off` to turn if off completely."
 	webIsWritableMessage    = "*Everyone in this channel* can write to this terminal. Use `!web ro` to change it to read-only, and `!web off` to turn if off completely."
-	webEnabledMessage       = "The web terminal is available at http://%s/%s/"
+	webEnabledMessage       = "The web terminal is available at http://%s/%s"
 	webDisabledMessage      = "The web terminal is disabled."
 	webHelpMessage          = "To enable it, simply type `!web rw` (read-write) or `!web ro` (read-only). Type `!web off` to turn if back off."
-	webNotWorkingMessage    = "🙁 I'm sorry but I can't start the web terminal for you."
+	webNotWorkingMessage    = "🙁 I'm sorry, but I can't start the web terminal for you."
+	webNotSupportedMessage  = "🙁 I'm sorry, but the web terminal feature is not enabled."
 	helpMessage             = "Alright, buckle up. Here's a list of all the things you can do in this REPL session.\n\n" +
 		"Sending text:\n" +
 		"  `TEXT` - Sends _TEXT\\n_\n" +
@@ -495,9 +496,6 @@ func (s *session) shutdownHandler() error {
 	if s.shareConn != nil {
 		s.shareConn.Close()
 	}
-	if s.webCmd != nil {
-		s.conf.notifyWeb(s, false, s.webPrefix)
-	}
 	s.mu.Unlock()
 	return nil
 }
@@ -875,6 +873,9 @@ func (s *session) handleScreenCommand(_ string) error {
 }
 
 func (s *session) handleWebCommand(input string) error {
+	if s.conf.global.WebHost == "" {
+		return s.conn.Send(s.conf.control, webNotSupportedMessage)
+	}
 	toggle := strings.TrimSpace(strings.TrimPrefix(input, "!web"))
 	s.mu.RLock()
 	enabled := s.webCmd != nil
@@ -934,11 +935,16 @@ func (s *session) startWeb(permitWrite bool) error {
 		s.webPrefix = util.RandomString(10)
 	}
 	s.webWritable = permitWrite
-	if permitWrite {
-		s.webCmd = exec.Command("gotty", "--permit-write", "--address", "127.0.0.1", "--port", strconv.Itoa(s.webPort), "tmux", "attach", "-t", s.tmux.MainID())
-	} else {
-		s.webCmd = exec.Command("gotty", "--address", "localhost", "--port", strconv.Itoa(s.webPort), "tmux", "attach", "-t", s.tmux.MainID())
+	args := []string{
+		"--address", "127.0.0.1",
+		"--port", strconv.Itoa(s.webPort),
+		"--reconnect",
+		"tmux", "attach", "-t", s.tmux.MainID(),
+	}
+	if s.webWritable {
+		args = append([]string{"--permit-write"}, args...)
 	}
+	s.webCmd = exec.Command("gotty", args...)
 	if err := s.webCmd.Start(); err != nil {
 		s.webCmd = nil // Disable web!
 		return err

config/config.yml

@@ -126,6 +126,16 @@ bot-token: MUST_BE_SET
 #
 # web-address:
 
+# Start web terminal by default (only applicable if "web-address" is set). If turned on, a gotty web terminal
+# will be started by default for each session. This option defines the default behavior. It can be changed
+# using the "web" or "noweb" settings.
+#
+# Format:    true or false
+# Default:   false
+# Required:  No
+#
+# default-web: false
+
 # Timeout after which REPL sessions are terminated if there is no user input.
 #
 # Format:    <number>(hms), must be >1m

util/tmux.go

@@ -46,8 +46,12 @@ func CheckTmuxVersion() error {
 	return nil
 }
 
-// Tmux represents a tmux(1) process with one window and three panes, to allow us to resize the terminal of the
-// main pane (.2). The main pane is .2, so that if it exits there is no other pane to take its place.
+// Tmux represents a very special tmux(1) setup, specifially used for REPLbot. It consists of
+// two tmux sessions:
+// - session "replbot_$id_frame": session with one window and three panes to allow us to resize the terminal of the
+//   main pane (.2). The main pane is .2, so that if it exits there is no other pane to take its place, which is easily
+//   detectable by the other panes. The main pane (.2) connects to the main session (see below).
+// - session "replbot_$id_main": main session running the actual shell/REPL.
 type Tmux struct {
 	id            string
 	width, height int
@@ -179,6 +183,7 @@ func (s *Tmux) Stop() error {
 	return nil
 }
 
+// MainID returns the session identifier for the main tmux session
 func (s *Tmux) MainID() string {
 	return s.mainID()
 }