Change: no XFF header from Couper (#139)

Co-authored-by: Alex Schneider <alex.schneider@sevenval.com>

config/request/context_key.go

@@ -14,4 +14,5 @@ const (
 	RoundTripProxy
 	ServerName
 	Wildcard
+	XFF
 )

handler/transport/backend.go

@@ -118,6 +118,14 @@ func (b *Backend) RoundTrip(req *http.Request) (*http.Response, error) {
 		}
 	}
 
+	if xff, ok := req.Context().Value(request.XFF).(string); ok {
+		if xff != "" {
+			req.Header.Set("X-Forwarded-For", xff)
+		} else {
+			req.Header.Del("X-Forwarded-For")
+		}
+	}
+
 	setUserAgent(req)
 	req.Close = false
 	beresp, err := t.RoundTrip(req)

server/http.go

@@ -161,6 +161,7 @@ func (s *HTTPServer) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	uid := s.uidFn()
 	ctx := context.WithValue(req.Context(), request.UID, uid)
+	ctx = context.WithValue(ctx, request.XFF, req.Header.Get("X-Forwarded-For"))
 	*req = *req.WithContext(ctx)
 
 	req.Host = s.getHost(req)

server/http_endpoints_test.go

@@ -78,7 +78,7 @@ func TestEndpoints_Res(t *testing.T) {
 	}
 }
 
-func TestEndpoints_UpstreamBasicAuth(t *testing.T) {
+func TestEndpoints_UpstreamBasicAuthAndXFF(t *testing.T) {
 	client := newClient()
 	helper := test.New(t)
 
@@ -88,6 +88,8 @@ func TestEndpoints_UpstreamBasicAuth(t *testing.T) {
 	req, err := http.NewRequest(http.MethodGet, "http://example.com:8080/anything", nil)
 	helper.Must(err)
 
+	req.Header.Set("X-Forwarded-For", "1.2.3.4")
+
 	res, err := client.Do(req)
 	helper.Must(err)
 
@@ -111,4 +113,8 @@ func TestEndpoints_UpstreamBasicAuth(t *testing.T) {
 	if v := jsonResult.Headers.Get("Authorization"); v != "Basic dXNlcjpwYXNz" {
 		t.Errorf("Expected a valid 'Authorization' header, given '%s'", v)
 	}
+
+	if v := jsonResult.Headers.Get("X-Forwarded-For"); v != "1.2.3.4" {
+		t.Errorf("Unexpected XFF header given '%s'", v)
+	}
 }