Bug 1535697 - Part 1: Avoid calling AntiTrackingCommon::IsFirstPartyStorageAccessGrantedFor() more than once per channel; r=michal

Differential Revision: https://phabricator.services.mozilla.com/D28371

--HG--
extra : moz-landing-system : lando

netwerk/protocol/http/nsHttpChannel.cpp

@@ -334,6 +334,8 @@ nsHttpChannel::nsHttpChannel()
       mAuthConnectionRestartable(0),
       mChannelClassifierCancellationPending(0),
       mAsyncResumePending(0),
+      mHasBeenIsolatedChecked(0),
+      mIsIsolated(0),
       mPushedStream(nullptr),
       mLocalBlocklist(false),
       mOnTailUnblock(nullptr),
@@ -625,9 +627,7 @@ nsresult nsHttpChannel::ContinueOnBeforeConnect(bool aShouldUpgrade,
     mCaps |= NS_HTTP_DISABLE_TRR;
   }
 
-  bool isIsolated = mPrivateBrowsing ||
-                    !AntiTrackingCommon::IsFirstPartyStorageAccessGrantedFor(
-                        this, mURI, nullptr);
+  bool isIsolated = mPrivateBrowsing || IsIsolated();
 
   // Finalize ConnectionInfo flags before SpeculativeConnect
   mConnectionInfo->SetAnonymous((mLoadFlags & LOAD_ANONYMOUS) != 0);
@@ -3895,6 +3895,16 @@ nsresult nsHttpChannel::OpenCacheEntry(bool isHttps) {
   return OpenCacheEntryInternal(isHttps, mApplicationCache, true);
 }
 
+bool nsHttpChannel::IsIsolated() {
+  if (mHasBeenIsolatedChecked) {
+    return mIsIsolated;
+  }
+  mIsIsolated = !AntiTrackingCommon::IsFirstPartyStorageAccessGrantedFor(
+      this, mURI, nullptr);
+  mHasBeenIsolatedChecked = true;
+  return mIsIsolated;
+}
+
 nsresult nsHttpChannel::OpenCacheEntryInternal(
     bool isHttps, nsIApplicationCache *applicationCache,
     bool allowApplicationCache) {
@@ -4014,9 +4024,7 @@ nsresult nsHttpChannel::OpenCacheEntryInternal(
     extension.Append("TRR");
   }
 
-  if (IsThirdPartyTrackingResource() &&
-      !AntiTrackingCommon::IsFirstPartyStorageAccessGrantedFor(this, mURI,
-                                                               nullptr)) {
+  if (IsThirdPartyTrackingResource() && IsIsolated()) {
     nsCOMPtr<nsIURI> topWindowURI;
     rv = GetTopWindowURI(getter_AddRefs(topWindowURI));
     bool isDocument = false;

netwerk/protocol/http/nsHttpChannel.h

@@ -546,6 +546,8 @@ class nsHttpChannel final : public HttpBaseChannel,
   void SetOriginHeader();
   void SetDoNotTrack();
 
+  bool IsIsolated();
+
   already_AddRefed<nsChannelClassifier> GetOrCreateChannelClassifier();
 
   // Start an internal redirect to a new InterceptedHttpChannel which will
@@ -718,6 +720,14 @@ class nsHttpChannel final : public HttpBaseChannel,
   // Used to suspend any newly created pumps in mCallOnResume handler.
   uint32_t mAsyncResumePending : 1;
 
+  // True only when we have checked whether this channel has been isolated for
+  // anti-tracking purposes.
+  uint32_t mHasBeenIsolatedChecked : 1;
+  // True only when we have determined this channel should be isolated for
+  // anti-tracking purposes.  Can never ben true unless mHasBeenIsolatedChecked
+  // is true.
+  uint32_t mIsIsolated : 1;
+
   nsTArray<nsContinueRedirectionFunc> mRedirectFuncStack;
 
   // Needed for accurate DNS timing