freebsd-ports/www/waterfox/files/patch-bug1393283

commit d20c7d929c84
Author: Ethan <ettseng@mozilla.com>
Date:   Fri Sep 1 17:29:44 2017 +0800

    Bug 1393283 - Use the last ESR version as the spoofed Firefox version. r=tihuang, r=mcmanus
---
 .../test/browser/browser_navigator.js              |  2 +-
 netwerk/protocol/http/nsHttpHandler.cpp            | 16 +++----
 .../resistfingerprinting/nsRFPService.cpp          | 56 ++++++++++++++++++++++
 .../components/resistfingerprinting/nsRFPService.h |  3 ++
 4 files changed, 66 insertions(+), 11 deletions(-)

diff --git browser/components/resistfingerprinting/test/browser/browser_navigator.js browser/components/resistfingerprinting/test/browser/browser_navigator.js
index 25c393d8bb2a..9f52e34a9451 100644
--- browser/components/resistfingerprinting/test/browser/browser_navigator.js
+++ browser/components/resistfingerprinting/test/browser/browser_navigator.js
@@ -91,7 +91,7 @@ add_task(async function setup() {
 
   let appInfo = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULAppInfo);
   let appVersion = parseInt(appInfo.version);
-  let spoofedVersion = appVersion - (appVersion % 10);
+  let spoofedVersion = appVersion - ((appVersion - 3) % 7);
   spoofedUserAgent = `Mozilla/5.0 (${SPOOFED_OSCPU}; rv:${spoofedVersion}.0) Gecko/20100101 Firefox/${spoofedVersion}.0`;
 });
 
diff --git netwerk/protocol/http/nsHttpHandler.cpp netwerk/protocol/http/nsHttpHandler.cpp
index 31d0f8832732..b957d835b52f 100644
--- netwerk/protocol/http/nsHttpHandler.cpp
+++ netwerk/protocol/http/nsHttpHandler.cpp
@@ -461,16 +461,12 @@ nsHttpHandler::Init()
         mAppVersion.AssignLiteral(MOZ_APP_UA_VERSION);
     }
 
-    // Generating the spoofed userAgent for fingerprinting resistance.
-    // The browser version will be rounded down to a multiple of 10.
-    // By doing so, the anonymity group will cover more versions instead of one
-    // version.
-    uint32_t spoofedVersion = mAppVersion.ToInteger(&rv);
-    if (NS_SUCCEEDED(rv)) {
-        spoofedVersion = spoofedVersion - (spoofedVersion % 10);
-        mSpoofedUserAgent.Assign(nsPrintfCString(
-            "Mozilla/5.0 (%s; rv:%d.0) Gecko/%s Firefox/%d.0",
-            SPOOFED_OSCPU, spoofedVersion, LEGACY_BUILD_ID, spoofedVersion));
+    // Generating the spoofed User Agent for fingerprinting resistance.
+    rv = nsRFPService::GetSpoofedUserAgent(mSpoofedUserAgent);
+    if (NS_FAILED(rv)) {
+      // Empty mSpoofedUserAgent to make sure the unsuccessful spoofed UA string
+      // will not be used anywhere.
+      mSpoofedUserAgent.Truncate();
     }
 
     mSessionStartTime = NowInSeconds();
diff --git toolkit/components/resistfingerprinting/nsRFPService.cpp toolkit/components/resistfingerprinting/nsRFPService.cpp
index 94554200c3b8..96a2940c04a0 100644
--- toolkit/components/resistfingerprinting/nsRFPService.cpp
+++ toolkit/components/resistfingerprinting/nsRFPService.cpp
@@ -18,10 +18,13 @@
 #include "nsServiceManagerUtils.h"
 #include "nsString.h"
 #include "nsXULAppAPI.h"
+#include "nsPrintfCString.h"
 
 #include "nsIObserverService.h"
 #include "nsIPrefBranch.h"
 #include "nsIPrefService.h"
+#include "nsIXULAppInfo.h"
+#include "nsIXULRuntime.h"
 #include "nsJSUtils.h"
 
 #include "prenv.h"
@@ -162,6 +165,59 @@ nsRFPService::GetSpoofedPresentedFrames(double aTime, uint32_t aWidth, uint32_t
   return NSToIntFloor(time * sVideoFramesPerSec * ((100 - boundedDroppedRatio) / 100.0));
 }
 
+/* static */
+nsresult
+nsRFPService::GetSpoofedUserAgent(nsACString &userAgent)
+{
+  // This function generates the spoofed value of User Agent.
+  // We spoof the values of the platform and Firefox version, which could be
+  // used as fingerprinting sources to identify individuals.
+  // Reference of the format of User Agent:
+  // https://developer.mozilla.org/en-US/docs/Web/API/NavigatorID/userAgent
+  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
+
+  nsresult rv;
+  nsCOMPtr<nsIXULAppInfo> appInfo =
+    do_GetService("@mozilla.org/xre/app-info;1", &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoCString appVersion;
+  rv = appInfo->GetVersion(appVersion);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // The browser version will be spoofed as the last ESR version.
+  // By doing so, the anonymity group will cover more versions instead of one
+  // version.
+  uint32_t firefoxVersion = appVersion.ToInteger(&rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Starting from Firefox 10, Firefox ESR was released once every seven
+  // Firefox releases, e.g. Firefox 10, 17, 24, 31, and so on.
+  // We infer the last and closest ESR version based on this rule.
+  nsCOMPtr<nsIXULRuntime> runtime =
+    do_GetService("@mozilla.org/xre/runtime;1", &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoCString updateChannel;
+  rv = runtime->GetDefaultUpdateChannel(updateChannel);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // If we are running in Firefox ESR, determine whether the formula of ESR
+  // version has changed.  Once changed, we must update the formula in this
+  // function.
+  if (updateChannel.Equals("esr")) {
+    MOZ_ASSERT(((firefoxVersion % 7) == 3),
+      "Please udpate ESR version formula in nsRFPService.cpp");
+  }
+
+  uint32_t spoofedVersion = firefoxVersion - ((firefoxVersion - 3) % 7);
+  userAgent.Assign(nsPrintfCString(
+    "Mozilla/5.0 (%s; rv:%d.0) Gecko/%s Firefox/%d.0",
+    SPOOFED_OSCPU, spoofedVersion, LEGACY_BUILD_ID, spoofedVersion));
+
+  return rv;
+}
+
 nsresult
 nsRFPService::Init()
 {
diff --git toolkit/components/resistfingerprinting/nsRFPService.h toolkit/components/resistfingerprinting/nsRFPService.h
index cf1f688bb992..bad80383883b 100644
--- toolkit/components/resistfingerprinting/nsRFPService.h
+++ toolkit/components/resistfingerprinting/nsRFPService.h
@@ -49,6 +49,9 @@ public:
   static uint32_t GetSpoofedDroppedFrames(double aTime, uint32_t aWidth, uint32_t aHeight);
   static uint32_t GetSpoofedPresentedFrames(double aTime, uint32_t aWidth, uint32_t aHeight);
 
+  // This method generates the spoofed value of User Agent.
+  static nsresult GetSpoofedUserAgent(nsACString &userAgent);
+
 private:
   nsresult Init();