reload certificate on SIGHUP

README.md

@@ -6,13 +6,12 @@ protocol](https://gemini.circumlunar.space/docs/specification.gmi). Why built ye
 server? Because it's educational and that's the spirit of the protocol.
 
 Features
-- **zero conf**, if no certificate is available, gmifs can generates self-signed certs
+- **zero conf**, if no certificate is available, gmifs generates a self-signed cert
 - **zero dependencies**, Go standard library only
-- directory listing support
-- only modern tls ciphers (from [Mozilla's TLS ciphers recommendations](https://statics.tls.security.mozilla.org/server-side-tls-conf.json))
-- concurrent requests limiter
-- reloads ssl certs and flushes/reopens log files on SIGHUP
-- single file gemini implementation, focus on simplicity, no bells and whistles
+- directory listing support `-autoindex`
+- reloads ssl certs and reopens log files on SIGHUP, e.g. after Let's Encrypt renewal
+- KISS, single file gemini implementation, handler func in main
+- modern tls ciphers (from [Mozilla's TLS ciphers recommendations](https://statics.tls.security.mozilla.org/server-side-tls-conf.json))
 
 This tool is used alongside the markdown to gemtext converter
 [md2gmi](https://github.com/n0x1m/md2gmi).

gemini/gemini.go

@@ -91,6 +91,8 @@ type Server struct {
 	Logger *log.Logger
 
 	TLSConfig       *tls.Config
+	TLSConfigLoader func() (*tls.Config, error)
+
 	Handler      Handler // handler to invoke
 	ReadTimeout  time.Duration
 	MaxOpenConns int
@@ -115,14 +117,30 @@ func (s *Server) logf(format string, v ...interface{}) {
 	s.log(fmt.Sprintf(format, v...))
 }
 
+func (s *Server) loadTLS() (err error) {
+	s.TLSConfig, err = s.TLSConfigLoader()
+	return err
+}
+
 func (s *Server) ListenAndServe() error {
+	err := s.loadTLS()
+	if err != nil {
+		return err
+	}
+
 	hup := make(chan os.Signal, 1)
 	signal.Notify(hup, syscall.SIGHUP)
 	go func() {
 		for {
 			<-hup
+			s.log("reloading certificate")
 			if s.listener != nil {
-				// TODO: reload TLSConfig
+				err := s.loadTLS()
+				if err != nil {
+					fmt.Fprintf(os.Stderr, "critical: failed to load tls certs: %v", err)
+					os.Exit(1)
+				}
+
 				s.listener.Close()
 			}
 		}

gemini/gencert.go

@@ -11,7 +11,7 @@ import (
 )
 
 // GenX509KeyPair generates a TLS keypair with one week validity.
-func GenX509KeyPair(host string) (tls.Certificate, error) {
+func GenX509KeyPair(host string, daysvalid int) (tls.Certificate, error) {
 	now := time.Now()
 	template := &x509.Certificate{
 		SerialNumber: big.NewInt(now.Unix()),
@@ -20,7 +20,7 @@ func GenX509KeyPair(host string) (tls.Certificate, error) {
 			Organization: []string{host},
 		},
 		NotBefore:             now,
-		NotAfter:              now.AddDate(0, 0, 7),
+		NotAfter:              now.AddDate(0, 0, daysvalid),
 		BasicConstraintsValid: true,
 		IsCA:                  true,
 		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},

main.go

@@ -27,6 +27,7 @@ const (
 	defaultCertPath = ""
 	defaultKeyPath  = ""
 
+	autoCertDaysValid = 7
 	shutdownTimeout   = 10 * time.Second
 )
 
@@ -61,20 +62,6 @@ func main() {
 		}
 	}
 
-	var cert tls.Certificate
-	if crt != "" && key != "" {
-		log.Println("loading certificate from", crt)
-		cert, err = tls.LoadX509KeyPair(crt, key)
-		if err != nil {
-			log.Fatalf("server: loadkeys: %s", err)
-		}
-	} else if host != "" {
-		log.Println("generating self-signed temporary certificate")
-		cert, err = gemini.GenX509KeyPair(host)
-		if err != nil {
-			log.Fatalf("server: loadkeys: %s", err)
-		}
-	}
 	if host == "" {
 		fmt.Fprintf(os.Stderr, "a keypair with cert and key or at least a common name (hostname) is required for sni\n")
 		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
@@ -84,12 +71,12 @@ func main() {
 
 	mux := gemini.NewMux()
 	mux.Use(middleware.Logger(flogger))
-	mux.Handle(gemini.HandlerFunc(fileserver.Serve(root, true)))
+	mux.Handle(gemini.HandlerFunc(fileserver.Serve(root, autoindex)))
 
 	server := &gemini.Server{
 		Addr:            addr,
 		Hostname:        host,
-		TLSConfig:    gemini.TLSConfig(host, cert),
+		TLSConfigLoader: setupCertificate(crt, key, host),
 		Handler:         mux,
 		MaxOpenConns:    maxconns,
 		ReadTimeout:     time.Duration(timeout) * time.Second,
@@ -118,6 +105,25 @@ func main() {
 	cancel()
 }
 
+func setupCertificate(crt, key, host string) func() (*tls.Config, error) {
+	return func() (*tls.Config, error) {
+		if crt != "" && key != "" {
+			cert, err := tls.LoadX509KeyPair(crt, key)
+			if err != nil {
+				return nil, err
+			}
+			return gemini.TLSConfig(host, cert), nil
+		}
+
+		log.Println("generating self-signed temporary certificate")
+		cert, err := gemini.GenX509KeyPair(host, autoCertDaysValid)
+		if err != nil {
+			return nil, err
+		}
+		return gemini.TLSConfig(host, cert), nil
+	}
+}
+
 func setupLogger(dir, filename string) (*log.Logger, error) {
 	logger := log.New(os.Stdout, "", log.LUTC|log.Ldate|log.Ltime)