Improve filterResponseData

js/background/injections/content/filter_response_data.js

@@ -1,8 +1,30 @@
 if(injection_strategy != 'cookie') {
+
+  var should_intercept_content_type = function(content_type) {
+    var should_intercept = false;
+
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types
+    var splitted_content_type = content_type.toLowerCase().split(
+      ';'
+    )[0].toLowerCase().split('/');
+
+    var type = splitted_content_type[0];
+    var subtype = splitted_content_type[1];
+
+    // TODO: Improve content_type check to fix issue #107:
+    // https://github.com/gbaptista/luminous/issues/107
+    if (['text', 'application'].includes(type)) {
+      should_intercept = /html/.test(subtype);
+    }
+
+    return should_intercept;
+  }
+
   var interceptor_html_string = undefined;
   var data_html_string = undefined;
 
-  // TODO remove cache for development enviroment
+  // TODO: remove cache for development enviroment
   load_interceptor_element('filterResponseData', function(element) {
     interceptor_html_string = element_to_html_string(element);
   });
@@ -14,9 +36,27 @@ if(injection_strategy != 'cookie') {
   var encoder = new TextEncoder();
   var decoder = new TextDecoder('utf-8');
 
+  var requests_content_types = {};
+
+  var detect_request_type = function(request_details) {
+    requests_content_types[request_details.requestId] = undefined;
+
+    var url = url_for_request(request_details);
+
+    if(should_intercept_request(url)) {
+      for(let header of request_details.responseHeaders) {
+        if(header.name.toLowerCase() == 'content-type') {
+          requests_content_types[request_details.requestId] = header.value;
+        }
+      }
+    }
+  }
+
   var inject_interceptor_and_settings = function(request_details) {
     var url = url_for_request(request_details);
 
+    // TODO: Improve should_intercept_request to fix issue #107:
+    // https://github.com/gbaptista/luminous/issues/107
     if(should_intercept_request(url)) {
       var options = full_options_for_url(url);
 
@@ -32,12 +72,14 @@ if(injection_strategy != 'cookie') {
         var content_to_write = options_html_string + data_html_string + interceptor_html_string;
 
         filter.ondata = event => {
+          var content_type = requests_content_types[request_details.requestId];
+
           var content = decoder.decode(event.data, {stream: true});
 
           // binary content? Image, PDF...
           var binary = /\0/.exec(content);
 
-          if(!binary) {
+          if(!binary && should_intercept_content_type(content_type)) {
             var match = /DOCTYPE(.|[\r\n])*?>/i.exec(content);
 
             if(match && match.index < 10 && match[0].length < 200) {
@@ -61,6 +103,13 @@ if(injection_strategy != 'cookie') {
     return {};
   }
 
+  chrome.webRequest.onHeadersReceived.addListener(
+    detect_request_type,
+    { urls: ['<all_urls>'], types: ['main_frame', 'sub_frame'] },
+    ['responseHeaders', 'blocking']
+  );
+
+
   chrome.webRequest.onBeforeRequest.addListener(
     inject_interceptor_and_settings,
     { urls: ['<all_urls>'], types: ['main_frame', 'sub_frame'] },

js/background/strategy.js

@@ -7,6 +7,9 @@ if(
   &&
   browser.webRequest.filterResponseData
 ) {
+  // TODO: Use sync_data['advanced']['injection_strategy']
+  //       if 'TryFilterResponseData': 'filterResponseData'
+  //                             else: 'cookie'
 
   // has filterResponseData support (Firefox 57+ only)
   injection_strategy = 'filterResponseData';

js/content/initializer.js

@@ -1,3 +1,18 @@
+var should_inject_this_document = function() {
+  // thanks to: https://github.com/EFForg/privacybadger/pull/1954
+  if (
+    document instanceof HTMLDocument === false &&
+    (
+      document instanceof XMLDocument === false ||
+      document.createElement('div') instanceof HTMLDivElement === false
+    )
+  ) {
+    return false;
+  }
+
+  return true;
+}
+
 var intialize_luminous_injections = function(from) {
   if(from == 'cookie') {
     var injection_enabled = Cookies.get('le');
@@ -10,7 +25,7 @@ var intialize_luminous_injections = function(from) {
 
     if(from == 'cookie') {
       if(injection_enabled != 'f') {
-        fn(true);
+        fn(should_inject_this_document());
       }
     } else {
       fn(false);

js/content/strategy.js

@@ -15,8 +15,12 @@ if(typeof browser !== 'undefined') {
     // Firefox without filterResponseData support...
     injection_strategy = 'cookie';
   } else {
-    // Let's hope it's a Firefox 57+ or
-    // something with filterResponseData support.
+    // TODO: Use sync_data['advanced']['injection_strategy']
+    //       if 'TryFilterResponseData': 'filterResponseData'
+    //                             else: 'cookie'
+
+    // Let's hope it's a Firefox 57+ or something
+    // with filterResponseData support.
     injection_strategy = 'filterResponseData';
   }
 }