refactoring

app.go

@@ -94,7 +94,7 @@ type Config struct {
 
 	TLSCertPath       string
 	TLSKeyPath        string
-	TLSClientAuthMode string
+	TLSClientAuthMode tls.ClientAuthType
 
 	ACMEURL   string
 	ACMEEmail string
@@ -153,6 +153,27 @@ type Headscale struct {
 	requestedExpiryCache *cache.Cache
 }
 
+// Look up the TLS constant relative to user-supplied TLS client
+// authentication mode. If an unknown mode is supplied, the default
+// value, tls.RequireAnyClientCert, is returned. The returned boolean
+// indicates if the supplied mode was valid.
+func LookupTLSClientAuthMode(mode string) (tls.ClientAuthType, bool) {
+	switch mode {
+	case DisabledClientAuth:
+		// Client cert is _not_ required.
+		return tls.NoClientCert, true
+	case RelaxedClientAuth:
+		// Client cert required, but _not verified_.
+		return tls.RequireAnyClientCert, true
+	case EnforcedClientAuth:
+		// Client cert is _required and verified_.
+		return tls.RequireAndVerifyClientCert, true
+	default:
+        // Return the default when an unknown value is supplied.
+		return tls.RequireAnyClientCert, false
+	}
+}
+
 // NewHeadscale returns the Headscale app.
 func NewHeadscale(cfg Config) (*Headscale, error) {
 	privKey, err := readOrCreatePrivateKey(cfg.PrivateKeyPath)
@@ -655,17 +676,12 @@ func (h *Headscale) getTLSSettings() (*tls.Config, error) {
 			log.Warn().Msg("Listening with TLS but ServerURL does not start with https://")
 		}
 
-		clientAuthMode, err := h.GetClientAuthMode()
-		if err != nil {
-			return nil, err
-		}
-
 		log.Info().Msg(fmt.Sprintf(
 			"Client authentication (mTLS) is \"%s\". See the docs to learn about configuring this setting.",
 			h.cfg.TLSClientAuthMode))
 
 		tlsConfig := &tls.Config{
-			ClientAuth:   clientAuthMode,
+			ClientAuth:   h.cfg.TLSClientAuthMode,
 			NextProtos:   []string{"http/1.1"},
 			Certificates: make([]tls.Certificate, 1),
 			MinVersion:   tls.VersionTLS12,
@@ -677,25 +693,6 @@ func (h *Headscale) getTLSSettings() (*tls.Config, error) {
 	}
 }
 
-// Look up the TLS constant relative to user-supplied TLS client
-// authentication mode.
-func (h *Headscale) GetClientAuthMode() (tls.ClientAuthType, error) {
-	switch h.cfg.TLSClientAuthMode {
-	case DisabledClientAuth:
-		// Client cert is _not_ required.
-		return tls.NoClientCert, nil
-	case RelaxedClientAuth:
-		// Client cert required, but _not verified_.
-		return tls.RequireAnyClientCert, nil
-	case EnforcedClientAuth:
-		// Client cert is _required and verified_.
-		return tls.RequireAndVerifyClientCert, nil
-	default:
-		return tls.NoClientCert, Error("Invalid tls_client_auth_mode provided: " +
-			h.cfg.TLSClientAuthMode)
-	}
-}
-
 func (h *Headscale) setLastStateChangeToNow(namespace string) {
 	now := time.Now().UTC()
 	lastStateUpdate.WithLabelValues("", "headscale").Set(float64(now.Unix()))

cmd/headscale/cli/utils.go

@@ -30,6 +30,7 @@ const (
 )
 
 func LoadConfig(path string) error {
+
 	viper.SetConfigName("config")
 	if path == "" {
 		viper.AddConfigPath("/etc/headscale/")
@@ -87,9 +88,15 @@ func LoadConfig(path string) error {
 		errorText += "Fatal config error: server_url must start with https:// or http://\n"
 	}
 
-	clientAuthMode := viper.GetString("tls_client_auth_mode")
-	if clientAuthMode != "disabled" && clientAuthMode != "relaxed" && clientAuthMode != "enforced" {
-		errorText += "Invalid tls_client_auth_mode supplied. Accepted values: disabled, relaxed, enforced."
+	_, authModeValid := headscale.LookupTLSClientAuthMode(viper.GetString("tls_client_auth_mode"))
+
+	if !authModeValid {
+        errorText += fmt.Sprintf(
+            "Invalid tls_client_auth_mode supplied: %s. Accepted values: %s, %s, %s.",
+            viper.GetString("tls_client_auth_mode"),
+            headscale.DisabledClientAuth,
+            headscale.RelaxedClientAuth,
+            headscale.EnforcedClientAuth)
 	}
 
 	if errorText != "" {
@@ -280,6 +287,8 @@ func getHeadscaleConfig() headscale.Config {
 		log.Warn().Msgf("'ip_prefixes' not configured, falling back to default: %v", prefixes)
 	}
 
+    tlsClientAuthMode, _ := headscale.LookupTLSClientAuthMode(viper.GetString("tls_client_auth_mode"))
+
 	return headscale.Config{
 		ServerURL:      viper.GetString("server_url"),
 		Addr:           viper.GetString("listen_addr"),
@@ -310,7 +319,7 @@ func getHeadscaleConfig() headscale.Config {
 
 		TLSCertPath:       absPath(viper.GetString("tls_cert_path")),
 		TLSKeyPath:        absPath(viper.GetString("tls_key_path")),
-		TLSClientAuthMode: viper.GetString("tls_client_auth_mode"),
+		TLSClientAuthMode: tlsClientAuthMode,
 
 		DNSConfig: dnsConfig,
 

config-example.yaml

@@ -97,7 +97,7 @@ tls_letsencrypt_hostname: ""
 # - disabled: client authentication disabled
 # - relaxed: client certificate is required but not verified
 # - enforced: client certificate is required and verified
-tls_client_auth_mode: disabled
+tls_client_auth_mode: relaxed
 
 # Path to store certificates and metadata needed by
 # letsencrypt

docs/tls.md

@@ -33,7 +33,7 @@ tls_key_path: ""
 ### Configuring Mutual TLS Authentication (mTLS)
 
 mTLS is a method by which an HTTPS server authenticates clients, e.g. Tailscale,
-using TLS certificates. The capability can be configured by by applying one of
+using TLS certificates. The capability can be configured by applying one of
 the following values to the `tls_client_auth_mode` setting in the configuration
 file.