add banner opt back (#106)

* add banner opt back

* happy lint

cmd/sshpiperd/daemon.go

@@ -56,6 +56,23 @@ func newDaemon(ctx *cli.Context) (*daemon, error) {
 		return nil, fmt.Errorf("failed to listen for connection: %v", err)
 	}
 
+	bannertext := ctx.String("banner-text")
+	bannerfile := ctx.String("banner-file")
+
+	if bannertext != "" || bannerfile != "" {
+		config.BannerCallback = func(_ ssh.ConnMetadata, _ ssh.ChallengeContext) string {
+			if bannerfile != "" {
+				text, err := os.ReadFile(bannerfile)
+				if err != nil {
+					log.Warnf("cannot read banner file %v: %v", bannerfile, err)
+				} else {
+					return string(text)
+				}
+			}
+			return bannertext
+		}
+	}
+
 	return &daemon{
 		config:         config,
 		lis:            lis,

cmd/sshpiperd/main.go

@@ -115,6 +115,18 @@ func main() {
 				Usage:   "create typescript format screen recording and save into the directory see https://linux.die.net/man/1/script",
 				EnvVars: []string{"SSHPIPERD_TYPESCRIPT_LOG_DIR"},
 			},
+			&cli.StringFlag{
+				Name:    "banner-text",
+				Value:   "",
+				Usage:   "display a banner before authentication, would be ignored if banner file was set",
+				EnvVars: []string{"SSHPIPERD_BANNERTEXT"},
+			},
+			&cli.StringFlag{
+				Name:    "banner-file",
+				Value:   "",
+				Usage:   "display a banner from file before authentication",
+				EnvVars: []string{"SSHPIPERD_BANNERFILE"},
+			},
 		},
 		Action: func(ctx *cli.Context) error {
 			level, err := log.ParseLevel(ctx.String("log-level"))