kopia/internal/scrubber/scrub_sensitive.go

// Package scrubber contains helpers that remove sensitive information from Go structs before it's presented to users.
package scrubber

import (
	"reflect"
	"strings"
)

// ScrubSensitiveData returns a copy of a given value with sensitive fields scrubbed.
// Fields are marked as sensitive with struct field tag `kopia:"sensitive"`.
func ScrubSensitiveData(v reflect.Value) reflect.Value {
	switch v.Kind() {
	case reflect.Ptr:
		return ScrubSensitiveData(v.Elem()).Addr()

	case reflect.Struct:
		res := reflect.New(v.Type()).Elem()

		for i := range v.NumField() {
			fv := v.Field(i)

			sf := v.Type().Field(i)

			if sf.Tag.Get("kopia") == "sensitive" {
				if sf.Type.Kind() == reflect.String {
					res.Field(i).SetString(strings.Repeat("*", fv.Len()))
				}
			} else if sf.IsExported() {
				switch fv.Kind() {
				case reflect.Pointer:
					if !fv.IsNil() {
						fv = ScrubSensitiveData(fv.Elem()).Addr()
					}

				case reflect.Struct:
					fv = ScrubSensitiveData(fv)

				case reflect.Interface:
					if !fv.IsNil() {
						fv = ScrubSensitiveData(fv.Elem())
					}

				default: // Set the field as-is.
				}

				res.Field(i).Set(fv)
			}
		}

		return res

	default:
		panic("Unsupported type: " + v.String())
	}
}