web: add TLSConfig.IsEnabled() method

web/tls_config.go

@@ -90,6 +90,18 @@ func (c *FlagConfig) checkFlags() error {
 	return nil
 }
 
+// IsEnabled reports whether the TLSConfig configures TLS, i.e. whether at least
+// one TLS-related field is set. It does not validate that the configuration is
+// complete or that the referenced files exist; use ConfigToTLSConfig for that.
+// This is useful for callers that need to know whether the server will serve
+// HTTPS, for example to infer the scheme of an external URL.
+func (t *TLSConfig) IsEnabled() bool {
+	return t.TLSCertPath != "" || t.TLSCert != "" ||
+		t.TLSKeyPath != "" || t.TLSKey != "" ||
+		t.ClientCAs != "" || t.ClientCAsText != "" ||
+		t.ClientAuth != ""
+}
+
 // SetDirectory joins any relative file paths with dir.
 func (t *TLSConfig) SetDirectory(dir string) {
 	t.TLSCertPath = config_util.JoinDir(dir, t.TLSCertPath)
@@ -165,10 +177,7 @@ func getTLSConfig(configPath string) (*tls.Config, error) {
 }
 
 func validateTLSPaths(c *TLSConfig) error {
-	if c.TLSCertPath == "" && c.TLSCert == "" &&
-		c.TLSKeyPath == "" && c.TLSKey == "" &&
-		c.ClientCAs == "" && c.ClientCAsText == "" &&
-		c.ClientAuth == "" {
+	if !c.IsEnabled() {
 		return errNoTLSConfig
 	}
 

web/tls_config_test.go

@@ -712,3 +712,48 @@ func TestUsers(t *testing.T) {
 		t.Run(testInputs.Name, testInputs.Test)
 	}
 }
+
+func TestTLSConfigIsEnabled(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		config   TLSConfig
+		expected bool
+	}{
+		{
+			name:     "empty config",
+			config:   TLSConfig{},
+			expected: false,
+		},
+		{
+			name:     "only non-enabling fields set",
+			config:   TLSConfig{MinVersion: tls.VersionTLS12, PreferServerCipherSuites: true},
+			expected: false,
+		},
+		{
+			name:     "cert_file and key_file set",
+			config:   TLSConfig{TLSCertPath: "server.crt", TLSKeyPath: "server.key"},
+			expected: true,
+		},
+		{
+			name:     "inline cert and key set",
+			config:   TLSConfig{TLSCert: "cert", TLSKey: "key"},
+			expected: true,
+		},
+		{
+			name:     "only client CA file set",
+			config:   TLSConfig{ClientCAs: "client_ca.crt"},
+			expected: true,
+		},
+		{
+			name:     "only client auth type set",
+			config:   TLSConfig{ClientAuth: "RequireAndVerifyClientCert"},
+			expected: true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := tc.config.IsEnabled(); got != tc.expected {
+				t.Errorf("IsEnabled() = %v, expected %v", got, tc.expected)
+			}
+		})
+	}
+}