Add configuration option: debug_http_headers

doh-server/config.go

@@ -30,15 +30,16 @@ import (
 )
 
 type config struct {
-	Listen   []string `toml:"listen"`
-	Cert     string   `toml:"cert"`
-	Key      string   `toml:"key"`
-	Path     string   `toml:"path"`
-	Upstream []string `toml:"upstream"`
-	Timeout  uint     `toml:"timeout"`
-	Tries    uint     `toml:"tries"`
-	TCPOnly  bool     `toml:"tcp_only"`
-	Verbose  bool     `toml:"verbose"`
+	Listen           []string `toml:"listen"`
+	Cert             string   `toml:"cert"`
+	Key              string   `toml:"key"`
+	Path             string   `toml:"path"`
+	Upstream         []string `toml:"upstream"`
+	Timeout          uint     `toml:"timeout"`
+	Tries            uint     `toml:"tries"`
+	TCPOnly          bool     `toml:"tcp_only"`
+	Verbose          bool     `toml:"verbose"`
+	DebugHTTPHeaders []string `toml:"debug_http_headers"`
 }
 
 func loadConfig(path string) (*config, error) {

doh-server/server.go

@@ -112,6 +112,13 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 		const maxMemory = 32 << 20 // 32 MB
 		r.ParseMultipartForm(maxMemory)
 	}
+
+	for _, header := range s.conf.DebugHTTPHeaders {
+		if value:= r.Header.Get(header); value != "" {
+			log.Printf("%s: %s\n", header, value)
+		}
+	}
+
 	contentType := r.Header.Get("Content-Type")
 	if ct := r.FormValue("ct"); ct != "" {
 		contentType = ct