From f94b6c68aa26f55d3a90b1a99536f378fe466d53 Mon Sep 17 00:00:00 2001
From: Michael Jumper <mjumper@apache.org>
Date: Tue, 20 Jul 2021 18:49:43 -0700
Subject: [PATCH] GUACAMOLE-275: Request browser to always revalidate cached
 dynamic contents.

---
 .../java/org/apache/guacamole/resource/ResourceServlet.java   | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/guacamole/src/main/java/org/apache/guacamole/resource/ResourceServlet.java b/guacamole/src/main/java/org/apache/guacamole/resource/ResourceServlet.java
index a6cf97357..c61687ea3 100644
--- a/guacamole/src/main/java/org/apache/guacamole/resource/ResourceServlet.java
+++ b/guacamole/src/main/java/org/apache/guacamole/resource/ResourceServlet.java
@@ -68,6 +68,10 @@ public class ResourceServlet extends HttpServlet {
     protected void doHead(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
 
+        // Request that the browser revalidate cached data
+        response.addHeader("Cache-Control", "no-cache");
+        response.addHeader("Pragma", "no-cache");
+
         // Set last modified and content type headers
         response.addDateHeader("Last-Modified", resource.getLastModified());
         response.setContentType(resource.getMimeType());