Bug 1409570 - Ensure a pushed stream knows we've reached EOS. r=mcmanus

Previously, if a pushed stream was ended with a padding-only DATA frame
with the FIN bit set, and that stream didn't have a Content-Length,
there would be no way of knowing that the stream was finished. Now we
force-mark the push as complete if we hit a padding-only DATA frame with
the FIN bit set.

MozReview-Commit-ID: 7tk8x2FNgSj

--HG--
extra : rebase_source : b95f635b4bb0b4743cf81e888a455365ef561c22

netwerk/protocol/http/Http2Push.h

@@ -68,6 +68,7 @@ public:
 
   // overload of Http2Stream
   virtual bool HasSink() override { return !!mConsumerStream; }
+  virtual void SetPushComplete() override { mPushCompleted = true; }
 
   nsCString &GetRequestString() { return mRequestString; }
 

netwerk/protocol/http/Http2Session.cpp

@@ -3284,8 +3284,9 @@ Http2Session::WriteSegmentsAgain(nsAHttpSegmentWriter *writer,
     char trash[4096];
     uint32_t discardCount = std::min(mInputFrameDataSize - mInputFrameDataRead,
                                      4096U);
-    LOG3(("Http2Session::WriteSegments %p trying to discard %d bytes of data",
-          this, discardCount));
+    LOG3(("Http2Session::WriteSegments %p trying to discard %d bytes of %s",
+          this, discardCount,
+          mDownstreamState == DISCARDING_DATA_FRAME ? "data" : "padding"));
 
     if (!discardCount && mDownstreamState == DISCARDING_DATA_FRAME) {
       // Only do this short-cirtuit if we're not discarding a pure padding
@@ -3317,9 +3318,15 @@ Http2Session::WriteSegmentsAgain(nsAHttpSegmentWriter *writer,
         streamToCleanup = mInputFrameDataStream;
       }
 
+      bool discardedPadding = (mDownstreamState == DISCARDING_DATA_FRAME_PADDING);
       ResetDownstreamState();
 
       if (streamToCleanup) {
+        if (discardedPadding && !(streamToCleanup->StreamID() & 1)) {
+          // Pushed streams are special on padding-only final data frames.
+          // See bug 1409570 comments 6-8 for details.
+          streamToCleanup->SetPushComplete();
+        }
         CleanupStream(streamToCleanup, NS_OK, CANCEL_ERROR);
       }
     }

netwerk/protocol/http/Http2Stream.h

@@ -153,6 +153,9 @@ public:
   // once it is matched to a pull stream.
   virtual bool HasSink() { return true; }
 
+  // This is a no-op on pull streams. Pushed streams override this.
+  virtual void SetPushComplete() { };
+
   virtual ~Http2Stream();
 
   Http2Session *Session() { return mSession; }