add disable ecs option

doh-server/config.go

@@ -43,6 +43,7 @@ type config struct {
 	Tries               uint     `toml:"tries"`
 	Verbose             bool     `toml:"verbose"`
 	LogGuessedIP        bool     `toml:"log_guessed_client_ip"`
+	ECSDisable          bool     `toml:"ecs_disable"`
 	ECSAllowNonGlobalIP bool     `toml:"ecs_allow_non_global_ip"`
 	ECSUsePreciseIP     bool     `toml:"ecs_use_precise_ip"`
 	TLSClientAuth       bool     `toml:"tls_client_auth"`

doh-server/doh-server.conf

@@ -52,6 +52,10 @@ verbose = false
 # Note: http uri/useragent log cannot be controlled by this config
 log_guessed_client_ip = false
 
+# Disable ECS
+# If this item is set to true, edns will not work.
+ecs_disable = false;
+
 # By default, non global IP addresses are never forwarded to upstream servers.
 # This is to prevent two things from happening:
 #   1. the upstream server knowing your private LAN addresses;

doh-server/server.go

@@ -284,6 +284,10 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 }
 
 func (s *Server) findClientIP(r *http.Request) net.IP {
+	if s.conf.ECSDisable {
+		return nil
+	}
+
 	noEcs := r.URL.Query().Get("no_ecs")
 	if strings.EqualFold(noEcs, "true") {
 		return nil