Add admin interface

internal/server/delete.go

@@ -47,8 +47,15 @@ func (s *Server) handleDelete(w http.ResponseWriter, r *http.Request) {
 		writeJSON(w, http.StatusOK, map[string]string{"status": "deleted", "id": id})
 		return
 	}
+	// Deleting from the administration table goes back to it. The destination
+	// is built from configuration, never from the request, so this cannot be
+	// turned into an open redirect.
+	if r.PostFormValue("from") == "admin" {
+		http.Redirect(w, r, s.cfg.BasePath+"admin", http.StatusSeeOther)
+		return
+	}
 	s.render(w, http.StatusOK, "error.html", errorPage{
-		page:    s.page("Deleted", false),
+		page:    s.page(r, "Deleted", false),
 		Status:  "Deleted",
 		Message: "The file is gone.",
 	})