feat(serverHandler/json): set optional header if missing

Author: marjune163

src/serverHandler/content.go

@@ -38,7 +38,7 @@ func (h *aliasHandler) content(w http.ResponseWriter, r *http.Request, data *res
 	}
 
 	header.Set("Accept-Ranges", "bytes")
-	if len(header.Values("Content-Type")) == 0 {
+	if lacksHeader(header, "Content-Type") {
 		ctype, err := util.GetContentType(item.Name(), file)
 		if err == nil {
 			header.Set("Content-Type", ctype)

src/serverHandler/json.go

@@ -78,7 +78,9 @@ func getJsonData(data *responseData) *jsonResponseData {
 func (h *aliasHandler) json(w http.ResponseWriter, r *http.Request, data *responseData) {
 	header := w.Header()
 	header.Set("Content-Type", "application/json; charset=utf-8")
-	header.Set("Cache-Control", "public, max-age=0")
+	if lacksHeader(header, "Cache-Control") {
+		header.Set("Cache-Control", "public, max-age=0")
+	}
 
 	if !NeedResponseBody(r.Method) {
 		w.WriteHeader(data.Status)

src/serverHandler/page.go

@@ -66,7 +66,7 @@ func (h *aliasHandler) page(w http.ResponseWriter, r *http.Request, data *respon
 	header := w.Header()
 	header.Set("X-Content-Type-Options", "nosniff")
 	header.Set("Content-Type", "text/html; charset=utf-8")
-	if len(header.Values("Cache-Control")) == 0 {
+	if lacksHeader(header, "Cache-Control") {
 		header.Set("Cache-Control", "public, max-age=0")
 	}
 

src/serverHandler/util.go

@@ -45,6 +45,10 @@ func NeedResponseBody(method string) bool {
 		method != http.MethodTrace
 }
 
+func lacksHeader(header http.Header, key string) bool {
+	return len(header.Values(key)) == 0
+}
+
 func getCleanFilePath(requestPath string) (filePath string, ok bool) {
 	filePath = path.Clean(requestPath)
 	ok = filePath == path.Base(filePath)