Add an extractor for DOM features to be used for client side phishing detection.

chrome/renderer/safe_browsing/phishing_dom_feature_extractor.h

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// PhishingDOMFeatureExtractor handles computing DOM-based features for the
+// client-side phishing detection model.  These include the presence of various
+// types of elements, ratios of external and secure links, and tokens for
+// external domains linked to.
+
+#ifndef CHROME_RENDERER_SAFE_BROWSING_PHISHING_DOM_FEATURE_EXTRACTOR_H_
+#define CHROME_RENDERER_SAFE_BROWSING_PHISHING_DOM_FEATURE_EXTRACTOR_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/scoped_ptr.h"
+#include "base/task.h"
+
+class GURL;
+class RenderView;
+
+namespace WebKit {
+class WebElement;
+class WebFrame;
+}
+
+namespace safe_browsing {
+class FeatureMap;
+
+class PhishingDOMFeatureExtractor {
+ public:
+  // Callback to be run when feature extraction finishes.  The callback
+  // argument is true if extraction was successful, false otherwise.
+  typedef Callback1<bool>::Type DoneCallback;
+
+  // Creates a PhishingDOMFeatureExtractor for the specified RenderView.
+  // The PhishingDOMFeatureExtrator should be destroyed prior to destroying
+  // the RenderView.
+  explicit PhishingDOMFeatureExtractor(RenderView* render_view);
+  ~PhishingDOMFeatureExtractor();
+
+  // Begins extracting features into the given FeatureMap for the page
+  // currently loaded in this object's RenderView.  To avoid blocking the
+  // render thread for too long, the feature extractor may run in several
+  // chunks of work, posting a task to the current MessageLoop to continue
+  // processing.  Once feature extraction is complete, |done_callback|
+  // is run.  PhishingDOMFeatureExtractor takes ownership of the callback.
+  void ExtractFeatures(FeatureMap* features, DoneCallback* done_callback);
+
+  // Cancels any pending feature extraction.  The DoneCallback will not be run.
+  // Must be called if there is a feature extraction in progress when the page
+  // is unloaded or the PhishingDOMFeatureExtractor is destroyed.
+  void CancelPendingExtraction();
+
+ private:
+  struct FrameData;
+  struct PageFeatureState;
+
+  // Does the actual work of ExtractFeatures.  ExtractFeaturesWithTimeout runs
+  // until a predefined maximum amount of time has elapsed, then posts a task
+  // to the current MessageLoop to continue extraction.  When extraction
+  // finishes, calls RunCallback().
+  void ExtractFeaturesWithTimeout();
+
+  // Handlers for the various HTML elements that we compute features for.
+  // Since some of the features (such as ratios) cannot be computed until
+  // feature extraction is finished, these handlers do not add to the feature
+  // map directly.  Instead, they update the values in the PageFeatureState.
+  void HandleLink(const WebKit::WebElement& element);
+  void HandleForm(const WebKit::WebElement& element);
+  void HandleImage(const WebKit::WebElement& element);
+  void HandleInput(const WebKit::WebElement& element);
+  void HandleScript(const WebKit::WebElement& element);
+
+  // Helper to verify that there is no pending feature extraction.  Dies in
+  // debug builds if the state is not as expected.  This is a no-op in release
+  // builds.
+  void CheckNoPendingExtraction();
+
+  // Runs |done_callback_| and then clears all internal state.
+  void RunCallback(bool success);
+
+  // Clears all internal feature extraction state.
+  void Clear();
+
+  // Called after advancing |cur_frame_| to update the state in
+  // |cur_frame_data_|.  Returns true if the state was updated successfully.
+  bool ResetFrameData();
+
+  // Given a URL, checks whether the domain is different from the domain of
+  // the current frame's URL.  If so, stores the domain in |domain| and returns
+  // true, otherwise returns false.
+  bool IsExternalDomain(const GURL& url, std::string* domain) const;
+
+  // Called once all frames have been processed to compute features from the
+  // PageFeatureState and add them to |features_|.  See features.h for a
+  // description of which features are computed.
+  void InsertFeatures();
+
+  // Non-owned pointer to the view that we will extract features from.
+  RenderView* render_view_;
+
+  // The output parameters from the most recent call to ExtractFeatures().
+  FeatureMap* features_;  // The caller keeps ownership of this.
+  scoped_ptr<DoneCallback> done_callback_;
+
+  // Non-owned pointer to the current frame that we are processing.
+  WebKit::WebFrame* cur_frame_;
+
+  // Stores extra state for |cur_frame_| that will be persisted until we
+  // advance to the next frame.
+  scoped_ptr<FrameData> cur_frame_data_;
+
+  // Stores the intermediate data used to create features.  This data is
+  // accumulated across all frames in the RenderView.
+  scoped_ptr<PageFeatureState> page_feature_state_;
+
+  // Used to create ExtractFeaturesWithTimeout tasks.
+  // These tasks are revoked if extraction is cancelled.
+  ScopedRunnableMethodFactory<PhishingDOMFeatureExtractor> method_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PhishingDOMFeatureExtractor);
+};
+
+}  // namespace safe_browsing
+
+#endif  // CHROME_RENDERER_SAFE_BROWSING_PHISHING_DOM_FEATURE_EXTRACTOR_H_