Accept empty base64 inputs (#1013)

Author: wolveix

validate.go

@@ -47,7 +47,7 @@ var rxHostname = regexp.MustCompile(`^([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]{0,61
 var rxURITemplate = regexp.MustCompile("^([^{]*({[^}]*})?)*$")
 var rxJSONPointer = regexp.MustCompile("^(?:/(?:[^~/]|~0|~1)*)*$")
 var rxRelJSONPointer = regexp.MustCompile("^(?:0|[1-9][0-9]*)(?:#|(?:/(?:[^~/]|~0|~1)*)*)$")
-var rxBase64 = regexp.MustCompile(`^[a-zA-Z0-9+/_-]+=*$`)
+var rxBase64 = regexp.MustCompile(`^[a-zA-Z0-9+/_-]*=*$`)
 
 func mapTo[A, B any](s []A, f func(A) B) []B {
 	r := make([]B, len(s))

validate_test.go

@@ -621,13 +621,27 @@ var validateTests = []struct {
 		}](),
 		input: map[string]any{"value": []byte("ABCD")},
 	},
+	{
+		name: "base64 empty byte success",
+		typ: reflect.TypeFor[struct {
+			Value []byte "json:\"value\""
+		}](),
+		input: map[string]any{"value": []byte("")},
+	},
 	{
 		name: "base64 string success",
 		typ: reflect.TypeFor[struct {
 			Value string "json:\"value\" encoding:\"base64\""
 		}](),
 		input: map[string]any{"value": "ABCD"},
 	},
+	{
+		name: "base64 empty string success",
+		typ: reflect.TypeFor[struct {
+			Value string "json:\"value\" encoding:\"base64\""
+		}](),
+		input: map[string]any{"value": ""},
+	},
 	{
 		name: "base64 fail",
 		typ: reflect.TypeFor[struct {