Take User-Agent out of common library, that would be better for packaging

doh-server/server.go

@@ -102,8 +102,8 @@ func (s *Server) Start() error {
 }
 
 func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("Server", jsonDNS.USER_AGENT)
-	w.Header().Set("X-Powered-By", jsonDNS.USER_AGENT)
+	w.Header().Set("Server", USER_AGENT)
+	w.Header().Set("X-Powered-By", USER_AGENT)
 
 	if r.Form == nil {
 		const maxMemory = 32 << 20 // 32 MB

doh-server/version.go

@@ -0,0 +1,27 @@
+/*
+   DNS-over-HTTPS
+   Copyright (C) 2017-2018 Star Brilliant <m13253@hotmail.com>
+
+   Permission is hereby granted, free of charge, to any person obtaining a
+   copy of this software and associated documentation files (the "Software"),
+   to deal in the Software without restriction, including without limitation
+   the rights to use, copy, modify, merge, publish, distribute, sublicense,
+   and/or sell copies of the Software, and to permit persons to whom the
+   Software is furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+   DEALINGS IN THE SOFTWARE.
+*/
+
+package main
+
+const VERSION = "1.3.3"
+const USER_AGENT = "DNS-over-HTTPS/" + VERSION + " (+https://github.com/m13253/dns-over-https)"