Continued work on web host feature

bot/bot.go

@@ -13,6 +13,8 @@ import (
 	"heckel.io/replbot/util"
 	"log"
 	"net"
+	"net/http"
+	"net/http/httputil"
 	"os"
 	"strings"
 	"sync"
@@ -62,6 +64,7 @@ type Bot struct {
 	conn      conn
 	sessions  map[string]*session
 	shareUser map[string]*session
+	webID     map[string]*session
 	cancelFn  context.CancelFunc
 	mu        sync.RWMutex
 }
@@ -110,6 +113,11 @@ func (b *Bot) Run() error {
 			return b.runShareServer(ctx)
 		})
 	}
+	if b.config.WebHost != "" {
+		g.Go(func() error {
+			return b.runWebServer(ctx)
+		})
+	}
 	return g.Wait()
 }
 
@@ -368,6 +376,49 @@ func (b *Bot) handleHelp(channel, thread string, err error) error {
 	return b.conn.Send(target, message)
 }
 
+func (b *Bot) runWebServer(ctx context.Context) error {
+	_, port, err := net.SplitHostPort(b.config.WebHost)
+	if err != nil {
+		return err
+	}
+	if port == "" {
+		port = "80"
+	}
+	errChan := make(chan error)
+	go func() {
+		http.HandleFunc("/", b.webHandler)
+		errChan <- http.ListenAndServe(":"+port, nil)
+	}()
+	select {
+	case err := <-errChan:
+		return err
+	case <-ctx.Done():
+		return nil
+	}
+}
+
+func (b *Bot) webHandler(w http.ResponseWriter, r *http.Request) {
+	parts := strings.Split(r.URL.Path, "/")
+	if len(parts) < 3 { // must be /prefix/, not just /prefix
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+	prefix := parts[1]
+	if prefix != "a" {
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+	proxy := &httputil.ReverseProxy{Director: func(r *http.Request) {
+		r.URL.Scheme = "http"
+		r.URL.Host = "localhost:10001"
+		r.URL.Path = strings.TrimPrefix(r.URL.Path, "/a")
+		r.URL.RawPath = strings.TrimPrefix(r.URL.Path, "/a")
+		r.Header.Set("Origin", fmt.Sprintf("http://%s", b.config.WebHost))
+		log.Printf("webProxyRequest: host=%s path=%s", r.Host, r.URL.Path)
+	}}
+	proxy.ServeHTTP(w, r)
+}
+
 func (b *Bot) runShareServer(ctx context.Context) error {
 	if err := os.WriteFile(shareServerScriptFile, []byte(shareServerScriptSource), 0700); err != nil {
 		return err

bot/session.go

@@ -84,7 +84,7 @@ const (
 		"Other commands:\n" +
 		"  `!! ..` - Comment, ignored entirely\n" +
 		"  `!allow ..`, `!deny ..` - Allow/deny users\n" +
-		"  `!web` - Start web terminal\n" +
+		"  `!web` - Start/stop web terminal\n" +
 		"  `!resize ..` - Resize window\n" +
 		"  `!screen`, `!s` - Re-send terminal\n" +
 		"  `!alive` - Reset session timeout\n" +
@@ -187,7 +187,7 @@ type sessionConfig struct {
 	size        *config.Size
 	share       *shareConfig
 	record      bool
-	webTerm     bool
+	web         bool
 }
 
 type shareConfig struct {
@@ -271,6 +271,9 @@ func (s *session) Run() error {
 	if err != nil {
 		return err
 	}
+	if err := s.maybeStartWeb(); err != nil {
+		return err
+	}
 	if err := s.maybeSendStartShareMessage(); err != nil {
 		return err
 	}
@@ -519,12 +522,12 @@ func (s *session) sessionStartedMessage() string {
 	switch s.conf.authMode {
 	case config.OnlyMe:
 		message += "\n\n" + onlyMeModeMessage
-		if s.conf.webTerm {
+		if s.conf.web {
 			message += "\n\n" + "You may also view the session here: http://plop.datto.lan/lalala"
 		}
 	case config.Everyone:
 		message += "\n\n" + everyoneModeMessage
-		if s.conf.webTerm {
+		if s.conf.web {
 			message += "\n\n" + "*Danger*: In addition to this chat, you can also control the session from here: http://plop.datto.lan/lalala"
 		}
 	}
@@ -718,6 +721,14 @@ func (s *session) sendExitedMessageWithRecording() error {
 	return s.conn.UploadFile(s.conf.control, message, recordingFileName, recordingFileType, file)
 }
 
+func (s *session) maybeStartWeb() error {
+	if !s.conf.web {
+		return nil
+	}
+	// FIXME
+	return s.maybeRestartGotty()
+}
+
 func (s *session) maybeSendStartShareMessage() error {
 	if s.conf.share == nil {
 		return nil
@@ -769,7 +780,7 @@ func (s *session) handleEscapeCommand(input string) error {
 	return s.tmux.Paste(input)
 }
 
-func (s *session) handleKeepaliveCommand(input string) error {
+func (s *session) handleKeepaliveCommand(_ string) error {
 	return s.conn.Send(s.conf.control, sessionKeptAliveMessage)
 }
 
@@ -885,6 +896,11 @@ func (s *session) handleWebCommand(input string) error {
 func (s *session) maybeRestartGotty() error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
+	/*host, port, err := net.SplitHostPort(s.conf.global.WebHost)
+	if err != nil {
+		return err
+	}*/
+
 	if s.webCmd != nil && s.webCmd.Process != nil {
 		_ = s.webCmd.Process.Kill()
 	}

cmd/app.go

@@ -35,6 +35,7 @@ func New() *cli.App {
 		altsrc.NewBoolFlag(&cli.BoolFlag{Name: "upload-recording", Aliases: []string{"z"}, EnvVars: []string{"REPLBOT_UPLOAD_RECORDING"}, Usage: "upload recorded sessions via 'asciinema upload'"}),
 		altsrc.NewBoolFlag(&cli.BoolFlag{Name: "no-upload-recording", Aliases: []string{"Z"}, EnvVars: []string{"REPLBOT_NO_UPLOAD_RECORDING"}, Usage: "do not upload recorded sessions via 'asciinema upload'"}),
 		altsrc.NewStringFlag(&cli.StringFlag{Name: "cursor", Aliases: []string{"C"}, EnvVars: []string{"REPLBOT_CURSOR"}, Value: "on", Usage: "cursor blink rate (on, off or duration)"}),
+		altsrc.NewStringFlag(&cli.StringFlag{Name: "web-host", Aliases: []string{"W"}, EnvVars: []string{"REPLBOT_WEB_ADDRESS"}, Usage: "hostname:port used to provide the web terminal feature"}),
 		altsrc.NewStringFlag(&cli.StringFlag{Name: "share-host", Aliases: []string{"H"}, EnvVars: []string{"REPLBOT_SHARE_HOST"}, Usage: "SSH hostname:port, used for terminal sharing"}),
 		altsrc.NewStringFlag(&cli.StringFlag{Name: "share-key-file", Aliases: []string{"K"}, EnvVars: []string{"REPLBOT_SHARE_KEY_FILE"}, Value: "/etc/replbot/hostkey", Usage: "SSH host key file, used for terminal sharing"}),
 	}
@@ -68,6 +69,7 @@ func execRun(c *cli.Context) error {
 	defaultWindowMode := config.WindowMode(c.String("default-window-mode"))
 	defaultAuthMode := config.AuthMode(c.String("default-auth-mode"))
 	cursor := c.String("cursor")
+	webHost := c.String("web-host")
 	shareHost := c.String("share-host")
 	shareKeyFile := c.String("share-key-file")
 	debug := c.Bool("debug")
@@ -128,6 +130,7 @@ func execRun(c *cli.Context) error {
 	conf.DefaultRecord = defaultRecord
 	conf.UploadRecording = uploadRecording
 	conf.Cursor = cursorRate
+	conf.WebHost = webHost
 	conf.ShareHost = shareHost
 	conf.ShareKeyFile = shareKeyFile
 	conf.Debug = debug

config/config.go

@@ -40,6 +40,7 @@ type Config struct {
 	DefaultAuthMode    AuthMode
 	DefaultSize        *Size
 	Cursor             time.Duration
+	WebHost            string
 	ShareHost          string
 	ShareKeyFile       string
 	DefaultRecord      bool

config/config.yml

@@ -115,6 +115,17 @@ bot-token: MUST_BE_SET
 #
 # upload-recording: false
 
+# Hostname and port of the web server to support the web terminal feature via the !web command.
+# The socket is bound to :port, but the hostname is used to provide the full URL.
+#
+# If no port is provided, port 80 is assumed.
+#
+# Format:    <hostname>[:<port>]
+# Default:   empty
+# Required:  No
+#
+# web-address:
+
 # Timeout after which REPL sessions are terminated if there is no user input.
 #
 # Format:    <number>(hms), must be >1m