Added changelog

This change more directly addresses the privacy concern where servers can identify whether a given client has previously downloaded some content. This tracking occurs when a request for an already-cached resource is sent to the server with an `If-None-Match` header. If the cached resource was previously received with a unique `ETag`, the server can uniquely identify the user. Rather than blocking the client from reading `ETag` values (which may be safely be used for other purposes; see #177), this change prevents servers from being informed about whether the client has any cached content.

Fixes #177.

CHANGELOG.md

@@ -15,6 +15,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Require Firefox >= 55
 - Require Chrome >= 37
 
+## [1.25.0] - 2022-XX-XX
+
+### Compatibility note
+- Require Firefox >= 55
+- Require Chrome >= 37
+
+### Changed
+- Incoming etags are no longer filtered, but outgoing responses are. This should fix some bugs with filtered etags. See [#124](https://github.com/ClearURLs/Addon/pull/214)
+
 ## [1.24.1] - 2022-03-25
 
 ### Compatibility note

core_js/eTagFilter.js

@@ -19,28 +19,29 @@
 /*jshint esversion: 6 */
 
 /**
- * Filters eTag headers from web requests.
+ * Filters headers containing eTag values from web requests.
  */
 function eTagFilter(requestDetails) {
-    if(!requestDetails.responseHeaders || !storage.eTagFiltering
+    if(!requestDetails.requestHeaders || !storage.eTagFiltering
         || storage.localHostsSkipping && checkLocalURL(new URL(requestDetails.url))) return {};
-    const responseHeaders = requestDetails.responseHeaders;
+    const requestHeaders = requestDetails.requestHeaders;
 
-    const filteredHeaders = responseHeaders.filter(header => {
-       return header.name.toLowerCase() !== "etag";
+    const filteredHeaders = requestHeaders.filter(header => {
+        // Browsers may automatically send an If-None-Match header with
+        return header.name.toLowerCase() !== "if-none-match";
     });
 
-    if(filteredHeaders.length < responseHeaders.length) {
+    if(filteredHeaders.length < requestHeaders.length) {
         pushToLog(requestDetails.url, requestDetails.url, translate("eTag_filtering_log"));
         increaseBadged(false, requestDetails);
         increaseGlobalURLCounter(1);
 
-        return {responseHeaders: filteredHeaders};
+        return {requestHeaders: filteredHeaders};
     }
 }
 
-browser.webRequest.onHeadersReceived.addListener(
+browser.webRequest.onBeforeSendHeaders.addListener(
     eTagFilter,
     {urls: ["<all_urls>"]},
-    ["blocking", "responseHeaders"]
+    ["blocking", "requestHeaders"]
 );

manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 2,
   "name": "ClearURLs",
-  "version": "1.24.1",
+  "version": "1.25.0",
   "author": "Kevin Roebert",
   "description": "__MSG_extension_description__",
   "homepage_url": "https://docs.clearurls.xyz",