webdav: don't override Referer if user sets it - fixes #6040

backend/webdav/webdav.go

@@ -454,7 +454,9 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	if err != nil {
 		return nil, err
 	}
-	f.srv.SetHeader("Referer", u.String())
+	if !f.findHeader(opt.Headers, "Referer") {
+		f.srv.SetHeader("Referer", u.String())
+	}
 
 	if root != "" && !rootIsDir {
 		// Check to see if the root actually an existing file
@@ -517,6 +519,17 @@ func (f *Fs) addHeaders(headers fs.CommaSepList) {
 	}
 }
 
+// Returns true if the header was configured
+func (f *Fs) findHeader(headers fs.CommaSepList, find string) bool {
+	for i := 0; i < len(headers); i += 2 {
+		key := f.opt.Headers[i]
+		if strings.EqualFold(key, find) {
+			return true
+		}
+	}
+	return false
+}
+
 // fetch the bearer token and set it if successful
 func (f *Fs) fetchAndSetBearerToken() error {
 	if f.opt.BearerTokenCommand == "" {