add options for ECS full subnet mask in server & TLS verification bypass in client (#92)

* add ECS full size & limit filtering

* add tls certification bypass in configuration

* flush log lines

* changes following pull request comments

* with fmt and reorg of libs in client.go

doh-server/server.go

@@ -265,17 +265,22 @@ func (s *Server) findClientIP(r *http.Request) net.IP {
 	if XRealIP != "" {
 		addr := strings.TrimSpace(XRealIP)
 		ip := net.ParseIP(addr)
-		if jsondns.IsGlobalIP(ip) {
+		if !s.conf.LocalIPFilter || jsondns.IsGlobalIP(ip) {
 			return ip
 		}
 	}
+
 	remoteAddr, err := net.ResolveTCPAddr("tcp", r.RemoteAddr)
 	if err != nil {
 		return nil
 	}
+	if !s.conf.LocalIPFilter {
+		return remoteAddr.IP
+	}
 	if ip := remoteAddr.IP; jsondns.IsGlobalIP(ip) {
 		return ip
 	}
+
 	return nil
 }