From 53d76b666420239ff7f03dcb89ed2eb4b3139c44 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sun, 26 Aug 2018 09:49:11 +0700
Subject: [PATCH] only use duplicate stream data error internally in the
 streamFrameSorter

---
 receive_stream.go           |  2 +-
 stream_frame_sorter.go      | 15 ++++++++++-----
 stream_frame_sorter_test.go | 14 +++++++-------
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/receive_stream.go b/receive_stream.go
index fd7a56bb..3a96c395 100644
--- a/receive_stream.go
+++ b/receive_stream.go
@@ -209,7 +209,7 @@ func (s *receiveStream) handleStreamFrame(frame *wire.StreamFrame) error {
 
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
-	if err := s.frameQueue.Push(frame.Data, frame.Offset, frame.FinBit); err != nil && err != errDuplicateStreamData {
+	if err := s.frameQueue.Push(frame.Data, frame.Offset, frame.FinBit); err != nil {
 		return err
 	}
 	s.signalRead()
diff --git a/stream_frame_sorter.go b/stream_frame_sorter.go
index 48812a6b..355b665d 100644
--- a/stream_frame_sorter.go
+++ b/stream_frame_sorter.go
@@ -14,10 +14,7 @@ type streamFrameSorter struct {
 	gaps        *utils.ByteIntervalList
 }
 
-var (
-	errTooManyGapsInReceivedStreamData = errors.New("Too many gaps in received StreamFrame data")
-	errDuplicateStreamData             = errors.New("Duplicate Stream Data")
-)
+var errDuplicateStreamData = errors.New("Duplicate Stream Data")
 
 func newStreamFrameSorter() *streamFrameSorter {
 	s := streamFrameSorter{
@@ -30,6 +27,14 @@ func newStreamFrameSorter() *streamFrameSorter {
 }
 
 func (s *streamFrameSorter) Push(data []byte, offset protocol.ByteCount, fin bool) error {
+	err := s.push(data, offset, fin)
+	if err == errDuplicateStreamData {
+		return nil
+	}
+	return err
+}
+
+func (s *streamFrameSorter) push(data []byte, offset protocol.ByteCount, fin bool) error {
 	if fin {
 		s.finalOffset = offset + protocol.ByteCount(len(data))
 	}
@@ -129,7 +134,7 @@ func (s *streamFrameSorter) Push(data []byte, offset protocol.ByteCount, fin boo
 	}
 
 	if s.gaps.Len() > protocol.MaxStreamFrameSorterGaps {
-		return errTooManyGapsInReceivedStreamData
+		return errors.New("Too many gaps in received data")
 	}
 
 	if wasCut {
diff --git a/stream_frame_sorter_test.go b/stream_frame_sorter_test.go
index 7221ee74..e0379cfb 100644
--- a/stream_frame_sorter_test.go
+++ b/stream_frame_sorter_test.go
@@ -375,21 +375,21 @@ var _ = Describe("STREAM frame sorter", func() {
 				})
 
 				It("does not modify data when receiving a duplicate", func() {
-					err := s.Push([]byte("fffff"), 0, false)
+					err := s.push([]byte("fffff"), 0, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[0]).ToNot(Equal([]byte("fffff")))
 				})
 
 				It("detects a duplicate frame that is smaller than the original, starting at the beginning", func() {
 					// 10 to 12
-					err := s.Push([]byte("12"), 10, false)
+					err := s.push([]byte("12"), 10, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[10]).To(HaveLen(5))
 				})
 
 				It("detects a duplicate frame that is smaller than the original, somewhere in the middle", func() {
 					// 1 to 4
-					err := s.Push([]byte("123"), 1, false)
+					err := s.push([]byte("123"), 1, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[0]).To(HaveLen(5))
 					Expect(s.queue).ToNot(HaveKey(protocol.ByteCount(1)))
@@ -397,7 +397,7 @@ var _ = Describe("STREAM frame sorter", func() {
 
 				It("detects a duplicate frame that is smaller than the original, somewhere in the middle in the last block", func() {
 					// 11 to 14
-					err := s.Push([]byte("123"), 11, false)
+					err := s.push([]byte("123"), 11, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[10]).To(HaveLen(5))
 					Expect(s.queue).ToNot(HaveKey(protocol.ByteCount(11)))
@@ -405,7 +405,7 @@ var _ = Describe("STREAM frame sorter", func() {
 
 				It("detects a duplicate frame that is smaller than the original, with aligned end in the last block", func() {
 					// 11 to 15
-					err := s.Push([]byte("1234"), 1, false)
+					err := s.push([]byte("1234"), 1, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[10]).To(HaveLen(5))
 					Expect(s.queue).ToNot(HaveKey(protocol.ByteCount(11)))
@@ -413,7 +413,7 @@ var _ = Describe("STREAM frame sorter", func() {
 
 				It("detects a duplicate frame that is smaller than the original, with aligned end", func() {
 					// 3 to 5
-					err := s.Push([]byte("12"), 3, false)
+					err := s.push([]byte("12"), 3, false)
 					Expect(err).To(MatchError(errDuplicateStreamData))
 					Expect(s.queue[0]).To(HaveLen(5))
 					Expect(s.queue).ToNot(HaveKey(protocol.ByteCount(3)))
@@ -427,7 +427,7 @@ var _ = Describe("STREAM frame sorter", func() {
 					}
 					Expect(s.gaps.Len()).To(Equal(protocol.MaxStreamFrameSorterGaps))
 					err := s.Push([]byte("foobar"), protocol.ByteCount(protocol.MaxStreamFrameSorterGaps*7)+100, false)
-					Expect(err).To(MatchError(errTooManyGapsInReceivedStreamData))
+					Expect(err).To(MatchError("Too many gaps in received data"))
 				})
 			})
 		})