Fix stale Content-Encoding header in ProxyServlet after HttpClient bump

api/src/org/mitre/dsmiley/httpproxy/LabKeyProxyServlet.java

@@ -1,13 +1,16 @@
 package org.mitre.dsmiley.httpproxy;
 
 import org.apache.commons.lang3.StringUtils;
+import org.apache.hc.core5.http.Header;
+import org.apache.hc.core5.http.HttpHeaders;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.labkey.api.util.PageFlowUtil;
 
 import jakarta.servlet.ServletException;
 import jakarta.servlet.http.Cookie;
 import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.net.HttpCookie;
 import java.util.Objects;
 
@@ -84,6 +87,23 @@ protected boolean skipXForwardedProto()
         return true;
     }
 
+    @Override
+    protected void copyResponseHeader(HttpServletRequest servletRequest, HttpServletResponse servletResponse, Header header)
+    {
+        // In Apache HttpClient <5.6.4, these headers were automatically removed after the client transparently
+        // decompressed the entity. Now we need to remove them manually, or the stale values reach the browser
+        // alongside the already-decompressed body.
+        if (doHandleCompression)
+        {
+            String headerName = header.getName();
+            if (headerName.equalsIgnoreCase(HttpHeaders.CONTENT_ENCODING) ||
+                    headerName.equalsIgnoreCase(HttpHeaders.CONTENT_LENGTH) ||
+                    headerName.equalsIgnoreCase(HttpHeaders.CONTENT_MD5))
+                return;
+        }
+        super.copyResponseHeader(servletRequest, servletResponse, header);
+    }
+
     @Override
     protected String getCookieNamePrefix(String cName)
     {

api/src/org/mitre/dsmiley/httpproxy/ProxyServlet.java

@@ -296,10 +296,14 @@ protected CloseableHttpClient createHttpClient() {
                 .setProtocolUpgradeEnabled(allowProtocolUpgrade()) // LKS override
                 .build();
 
-        return HttpClientBuilder.create()
-            .useSystemProperties()
-            .setDefaultRequestConfig(config)
-            .build();
+        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create()
+                .useSystemProperties()
+                .setDefaultRequestConfig(config);
+
+        if (!doHandleCompression)
+            httpClientBuilder.disableContentCompression();
+
+        return httpClientBuilder.build();
     }
 
     // LKS override