allow tls version setting

Author: Snawoot

dialer/upstream.go

@@ -94,6 +94,20 @@ func HTTPProxyDialerFromURL(u *url.URL, next xproxy.Dialer) (xproxy.Dialer, erro
 			}
 			tlsConfig.CurvePreferences = curveList
 		}
+		if params.Has("min-tls-version") {
+			ver, err := tlsutil.ParseVersion(params.Get("min-tls-version"))
+			if err != nil {
+				return nil, err
+			}
+			tlsConfig.MinVersion = ver
+		}
+		if params.Has("max-tls-version") {
+			ver, err := tlsutil.ParseVersion(params.Get("max-tls-version"))
+			if err != nil {
+				return nil, err
+			}
+			tlsConfig.MaxVersion = ver
+		}
 	default:
 		return nil, errors.New("unsupported proxy type")
 	}