client: Switch to case sensitive unmarshalling to be compatible with ugorji

Using lessons learned from k8s changes:
https://github.com/kubernetes/kubernetes/pull/65034

Change-Id: Ia17a8f94ae6ed00c5af2595c2b48d3c9a0344427

client/json.go

@@ -0,0 +1,72 @@
+// Copyright 2019 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package client
+
+import (
+	"github.com/json-iterator/go"
+	"github.com/modern-go/reflect2"
+	"strconv"
+	"unsafe"
+)
+
+type customNumberExtension struct {
+	jsoniter.DummyExtension
+}
+
+func (cne *customNumberExtension) CreateDecoder(typ reflect2.Type) jsoniter.ValDecoder {
+	if typ.String() == "interface {}" {
+		return customNumberDecoder{}
+	}
+	return nil
+}
+
+type customNumberDecoder struct {
+}
+
+func (customNumberDecoder) Decode(ptr unsafe.Pointer, iter *jsoniter.Iterator) {
+	switch iter.WhatIsNext() {
+	case jsoniter.NumberValue:
+		var number jsoniter.Number
+		iter.ReadVal(&number)
+		i64, err := strconv.ParseInt(string(number), 10, 64)
+		if err == nil {
+			*(*interface{})(ptr) = i64
+			return
+		}
+		f64, err := strconv.ParseFloat(string(number), 64)
+		if err == nil {
+			*(*interface{})(ptr) = f64
+			return
+		}
+		iter.ReportError("DecodeNumber", err.Error())
+	default:
+		*(*interface{})(ptr) = iter.Read()
+	}
+}
+
+// caseSensitiveJsonIterator returns a jsoniterator API that's configured to be
+// case-sensitive when unmarshalling, and otherwise compatible with
+// the encoding/json standard library.
+func caseSensitiveJsonIterator() jsoniter.API {
+	config := jsoniter.Config{
+		EscapeHTML:             true,
+		SortMapKeys:            true,
+		ValidateJsonRawMessage: true,
+		CaseSensitive:          true,
+	}.Froze()
+	// Force jsoniter to decode number to interface{} via int64/float64, if possible.
+	config.RegisterExtension(&customNumberExtension{})
+	return config
+}

client/keys.go

@@ -26,7 +26,6 @@ import (
 	"time"
 
 	"github.com/coreos/etcd/pkg/pathutil"
-	jsoniter "github.com/json-iterator/go"
 )
 
 const (
@@ -654,10 +653,11 @@ func unmarshalHTTPResponse(code int, header http.Header, body []byte) (res *Resp
 	return res, err
 }
 
+var jsonIterator = caseSensitiveJsonIterator()
+
 func unmarshalSuccessfulKeysResponse(header http.Header, body []byte) (*Response, error) {
 	var res Response
-	var json = jsoniter.ConfigCompatibleWithStandardLibrary
-	err := json.Unmarshal(body, &res)
+	err := jsonIterator.Unmarshal(body, &res)
 	if err != nil {
 		return nil, ErrInvalidJSON
 	}