jsonbytes: add package for JSON (en|de)coding byte slices as unpadded…

… base64

Signed-off-by: Sumner Evans <[email protected]>

jsonbytes/unpadded.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2024 Sumner Evans
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package jsonbytes
+
+import (
+	"encoding/base64"
+	"encoding/json"
+)
+
+// UnpaddedBytes is a byte slice that is encoded and decoded using
+// [base64.RawStdEncoding] instead of the default padded base64.
+type UnpaddedBytes []byte
+
+func (b UnpaddedBytes) MarshalJSON() ([]byte, error) {
+	return json.Marshal(base64.RawStdEncoding.EncodeToString(b))
+}
+
+func (b *UnpaddedBytes) UnmarshalJSON(data []byte) error {
+	var b64str string
+	err := json.Unmarshal(data, &b64str)
+	if err != nil {
+		return err
+	}
+	*b, err = base64.RawStdEncoding.DecodeString(b64str)
+	return err
+}