bug 1463356 do not count "not started" TRR resolves as failures r=mcmanus

... when comparing against the native resolver. DNS_TRR_COMPARE is meant
to compare how the actually performed name resolves fare against each
other.

MozReview-Commit-ID: 98NoUGPpHr6

--HG--
extra : rebase_source : 4042c81da3e5478de26feb7f83c98ee5eb298156

netwerk/dns/TRR.cpp

@@ -122,7 +122,7 @@ TRR::Run()
 {
   MOZ_ASSERT(NS_IsMainThread());
   if ((gTRRService == nullptr) || NS_FAILED(SendHTTPRequest())) {
-    FailData();
+    FailData(NS_ERROR_FAILURE);
     // The dtor will now be run
   }
   return NS_OK;
@@ -850,7 +850,7 @@ TRR::ReturnData()
 }
 
 nsresult
-TRR::FailData()
+TRR::FailData(nsresult error)
 {
   if (!mHostResolver) {
     return NS_ERROR_FAILURE;
@@ -859,7 +859,7 @@ TRR::FailData()
   // this comes from TRR
   AddrInfo *ai = new AddrInfo(mHost, mType);
 
-  (void)mHostResolver->CompleteLookup(mRec, NS_ERROR_FAILURE, ai, mPB);
+  (void)mHostResolver->CompleteLookup(mRec, error, ai, mPB);
   mHostResolver = nullptr;
   mRec = nullptr;
   return NS_OK;
@@ -933,7 +933,7 @@ TRR::OnStopRequest(nsIRequest *aRequest,
       // try and parse missing content-types, but otherwise require udpwireformat
       LOG(("TRR:OnStopRequest %p %s %d should fail due to content type %s\n",
            this, mHost.get(), mType, contentType.get()));
-      FailData();
+      FailData(NS_ERROR_UNEXPECTED);
       return NS_OK;
     }
 
@@ -952,7 +952,7 @@ TRR::OnStopRequest(nsIRequest *aRequest,
 
   LOG(("TRR:OnStopRequest %p status %x mFailed %d\n",
        this, (int)aStatusCode, mFailed));
-  FailData();
+  FailData(NS_ERROR_UNKNOWN_HOST);
   return NS_OK;
 }
 

netwerk/dns/TRR.h

@@ -147,7 +147,14 @@ private:
   nsresult GetQname(nsAutoCString &aQname, unsigned int &aIndex);
   nsresult DohDecode(nsCString &aHost);
   nsresult ReturnData();
-  nsresult FailData();
+
+  // FailData() must be called to signal that the asynch TRR resolve is
+  // completed. For failed name resolves ("no such host"), the 'error' it
+  // passses on in its argument must be NS_ERROR_UNKNOWN_HOST. Other errors
+  // (if host was blacklisted, there as a bad content-type received, etc)
+  // other error codes must be used. This distinction is important for the
+  // subsequent logic to separate the error reasons.
+  nsresult FailData(nsresult error);
   nsresult DohDecodeQuery(const nsCString &query,
                           nsCString &host, enum TrrType &type);
   nsresult ReceivePush(nsIHttpChannel *pushed, nsHostRecord *pushedRec);

netwerk/dns/nsHostResolver.cpp

@@ -184,6 +184,7 @@ nsHostRecord::nsHostRecord(const nsHostKey& key)
     , addr(nullptr)
     , negative(false)
     , mResolverMode(MODE_NATIVEONLY)
+    , mFirstTRRresult(NS_OK)
     , mResolving(0)
     , mTRRSuccess(0)
     , mNativeSuccess(0)
@@ -1519,6 +1520,7 @@ nsHostResolver::CompleteLookup(nsHostRecord* rec, nsresult status, AddrInfo* aNe
             rec->mTRRSuccess++;
         }
         if (TRROutstanding()) {
+            rec->mFirstTRRresult = status;
             if (NS_FAILED(status)) {
                 return LOOKUP_OK; // wait for outstanding
             }
@@ -1558,6 +1560,16 @@ nsHostResolver::CompleteLookup(nsHostRecord* rec, nsresult status, AddrInfo* aNe
                 rec->mFirstTRR = nullptr;
             }
 
+            if (NS_FAILED(rec->mFirstTRRresult) &&
+                NS_FAILED(status) &&
+                (rec->mFirstTRRresult != NS_ERROR_UNKNOWN_HOST) &&
+                (status != NS_ERROR_UNKNOWN_HOST)) {
+                // the errors are not failed resolves, that means
+                // something else failed, consider this as *TRR not used*
+                // for actually trying to resolve the host
+                rec->mTRRUsed = false;
+            }
+
             if (!rec->mTRRSuccess) {
                 // no TRR success
                 newRRSet = nullptr;
@@ -1570,6 +1582,7 @@ nsHostResolver::CompleteLookup(nsHostRecord* rec, nsresult status, AddrInfo* aNe
                 MOZ_ASSERT(rec->mResolving);
                 return LOOKUP_OK;
             }
+
             // continue
         }
 

netwerk/dns/nsHostResolver.h

@@ -174,6 +174,7 @@ private:
     explicit nsHostRecord(const nsHostKey& key);
     mozilla::LinkedList<RefPtr<nsResolveHostCallback>> mCallbacks;
     nsAutoPtr<mozilla::net::AddrInfo> mFirstTRR; // partial TRR storage
+    nsresult mFirstTRRresult;
 
     uint16_t  mResolving;  // counter of outstanding resolving calls
     uint8_t   mTRRSuccess; // number of successful TRR responses