From 9c1a71c164852a00dec4f1d0599050823314781c Mon Sep 17 00:00:00 2001
From: Arthur Edelstein <arthuredelstein@gmail.com>
Date: Mon, 24 Apr 2017 08:18:25 -0700
Subject: [PATCH] Bug 10286: Touch API fingerprinting resistance

---
 dom/events/Touch.cpp |  7 +++++++
 dom/events/Touch.h   | 16 ++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/dom/events/Touch.cpp b/dom/events/Touch.cpp
index a538fa6959d0a..39d50e3c65ca9 100644
--- a/dom/events/Touch.cpp
+++ b/dom/events/Touch.cpp
@@ -188,5 +188,12 @@ Touch::GetParentObject()
   return mTarget->GetOwnerGlobal();
 }
 
+bool
+Touch::ResistFingerprinting() const
+{
+  return !nsContentUtils::LegacyIsCallerChromeOrNativeCode() &&
+         nsContentUtils::ResistFingerprinting();
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/events/Touch.h b/dom/events/Touch.h
index f98f7f951f207..858fb165395ff 100644
--- a/dom/events/Touch.h
+++ b/dom/events/Touch.h
@@ -67,16 +67,19 @@ public:
   // WebIDL
   int32_t Identifier() const { return mIdentifier; }
   EventTarget* GetTarget() const;
-  int32_t ScreenX() const { return mScreenPoint.x; }
-  int32_t ScreenY() const { return mScreenPoint.y; }
+  int32_t ScreenX() const { return ResistFingerprinting() ?
+                                   mClientPoint.x : mScreenPoint.x; }
+  int32_t ScreenY() const { return ResistFingerprinting() ?
+                                   mClientPoint.y : mScreenPoint.y; }
   int32_t ClientX() const { return mClientPoint.x; }
   int32_t ClientY() const { return mClientPoint.y; }
   int32_t PageX() const { return mPagePoint.x; }
   int32_t PageY() const { return mPagePoint.y; }
-  int32_t RadiusX() const { return mRadius.x; }
-  int32_t RadiusY() const { return mRadius.y; }
-  float RotationAngle() const { return mRotationAngle; }
-  float Force() const { return mForce; }
+  int32_t RadiusX() const { return ResistFingerprinting() ? 1 : mRadius.x; }
+  int32_t RadiusY() const { return ResistFingerprinting() ? 1 : mRadius.y; }
+  float RotationAngle() const { return ResistFingerprinting() ?
+                                       0.0 : mRotationAngle; }
+  float Force() const { return ResistFingerprinting() ? 0.0 : mForce; }
 
   nsCOMPtr<EventTarget> mTarget;
   LayoutDeviceIntPoint mRefPoint;
@@ -90,6 +93,7 @@ public:
   float mRotationAngle;
   float mForce;
 protected:
+  bool ResistFingerprinting() const;
   ~Touch();
 
   bool mPointsInitialized;
-- 
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