Capture the contents of the User-Agent Header where possible (#25)

dns.go

@@ -195,7 +195,7 @@ func (s *ChallSrv) dohHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	s.dnsHandlerInner(&dnsToHTTPWriter{w}, msg)
+	s.dnsHandlerInner(&dnsToHTTPWriter{w}, msg, r.Header.Get("User-Agent"))
 }
 
 // dnsHandler is a miekg/dns handler that can process a dns.Msg request and
@@ -204,10 +204,10 @@ func (s *ChallSrv) dohHandler(w http.ResponseWriter, r *http.Request) {
 // DNS data. A host that is aliased by a CNAME record will follow that alias
 // one level and return the requested record types for that alias' target
 func (s *ChallSrv) dnsHandler(w dns.ResponseWriter, r *dns.Msg) {
-	s.dnsHandlerInner(w, r)
+	s.dnsHandlerInner(w, r, "")
 }
 
-func (s *ChallSrv) dnsHandlerInner(w writeMsg, r *dns.Msg) {
+func (s *ChallSrv) dnsHandlerInner(w writeMsg, r *dns.Msg, userAgent string) {
 	m := new(dns.Msg)
 	m.SetReply(r)
 	m.Compress = false
@@ -215,7 +215,8 @@ func (s *ChallSrv) dnsHandlerInner(w writeMsg, r *dns.Msg) {
 	// For each question, add answers based on the type of question
 	for _, q := range r.Question {
 		s.AddRequestEvent(DNSRequestEvent{
-			Question: q,
+			Question:  q,
+			UserAgent: userAgent,
 		})
 
 		// If there is a ServFail mock set then ignore the question and set the

event.go

@@ -38,6 +38,8 @@ type HTTPRequestEvent struct {
 	// The ServerName from the ClientHello. May be empty if there was no SNI or if
 	// the request was not HTTPS
 	ServerName string
+	// The User-Agent header from the request
+	UserAgent string
 }
 
 // HTTPRequestEvents always have type HTTPRequestEventType
@@ -59,6 +61,9 @@ func (e HTTPRequestEvent) Key() string {
 type DNSRequestEvent struct {
 	// The DNS question received.
 	Question dns.Question
+	// The User-Agent header from the request, may be empty
+	// if the request was not over DoH.
+	UserAgent string
 }
 
 // DNSRequestEvents always have type DNSRequestEventType

httpone.go

@@ -128,6 +128,7 @@ func (s *ChallSrv) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		Host:       r.Host,
 		HTTPS:      r.TLS != nil,
 		ServerName: serverName,
+		UserAgent:  r.Header.Get("User-Agent"),
 	})
 
 	// If the request was not over HTTPS and we have a redirect, serve it.