feat(service): add a new filter to support setting maxMemory manually…

… when parsing request form (#317)

Co-authored-by: iawia002 <xuxinzhao@caicloud.io>

service/filter.go

@@ -64,18 +64,18 @@ func FillLeadingSlash() Filter {
 	}
 }
 
-// ParseRequestForm returns a filter to parse request form when content
+// ParseRequestFormWithMaxMemory returns a filter to parse request form when content
 // type is "application/x-www-form-urlencoded" or "multipart/form-data".
 // The filter won't filter anything unless some error occurs in parsing.
-func ParseRequestForm() Filter {
+func ParseRequestFormWithMaxMemory(maxMemory int64) Filter {
 	return func(resp http.ResponseWriter, req *http.Request) bool {
 		ct, err := ContentType(req)
 		if err == nil {
 			switch ct {
 			case definition.MIMEURLEncoded:
 				err = req.ParseForm()
 			case definition.MIMEFormData:
-				err = req.ParseMultipartForm(32 << 20)
+				err = req.ParseMultipartForm(maxMemory)
 			default:
 				req.Form = req.URL.Query()
 			}
@@ -88,6 +88,12 @@ func ParseRequestForm() Filter {
 	}
 }
 
+// ParseRequestForm returns a filter to parse request form.
+// Same as ParseRequestFormWithMaxMemory, except that maxMemory is set to 32MB by default.
+func ParseRequestForm() Filter {
+	return ParseRequestFormWithMaxMemory(32 << 20)
+}
+
 // isGTZero returns a boolean result indicating if the content length is greater than 0.
 func isGTZero(length string) bool {
 	if length == "" {