From 5fc2e1203811b66f2e8c1124bae29e120f5c2aeb Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Thu, 11 Oct 2018 14:45:45 +0100
Subject: [PATCH] make the outgoing streams map work with stream 0

Stream 0 is now a valid stream ID used for application data, so the
streams map must be able to (block on) opening this stream.
---
 streams_map_outgoing_bidi.go         |  6 ++++--
 streams_map_outgoing_generic.go      |  6 ++++--
 streams_map_outgoing_generic_test.go | 17 +++++++++++++++++
 streams_map_outgoing_uni.go          |  6 ++++--
 4 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/streams_map_outgoing_bidi.go b/streams_map_outgoing_bidi.go
index ea9f47e6..ce3cd8c1 100644
--- a/streams_map_outgoing_bidi.go
+++ b/streams_map_outgoing_bidi.go
@@ -21,6 +21,7 @@ type outgoingBidiStreamsMap struct {
 
 	nextStream     protocol.StreamID // stream ID of the stream returned by OpenStream(Sync)
 	maxStream      protocol.StreamID // the maximum stream ID we're allowed to open
+	maxStreamSet   bool              // was maxStream set. If not, it's not possible to any stream (also works for stream 0)
 	highestBlocked protocol.StreamID // the highest stream ID that we queued a STREAM_ID_BLOCKED frame for
 
 	newStream            func(protocol.StreamID) streamI
@@ -71,7 +72,7 @@ func (m *outgoingBidiStreamsMap) openStreamImpl() (streamI, error) {
 	if m.closeErr != nil {
 		return nil, m.closeErr
 	}
-	if m.nextStream > m.maxStream {
+	if !m.maxStreamSet || m.nextStream > m.maxStream {
 		if m.maxStream == 0 || m.highestBlocked < m.maxStream {
 			m.queueStreamIDBlocked(&wire.StreamIDBlockedFrame{StreamID: m.maxStream})
 			m.highestBlocked = m.maxStream
@@ -108,8 +109,9 @@ func (m *outgoingBidiStreamsMap) DeleteStream(id protocol.StreamID) error {
 
 func (m *outgoingBidiStreamsMap) SetMaxStream(id protocol.StreamID) {
 	m.mutex.Lock()
-	if id > m.maxStream {
+	if !m.maxStreamSet || id > m.maxStream {
 		m.maxStream = id
+		m.maxStreamSet = true
 		m.cond.Broadcast()
 	}
 	m.mutex.Unlock()
diff --git a/streams_map_outgoing_generic.go b/streams_map_outgoing_generic.go
index f4b3eb61..5df1d685 100644
--- a/streams_map_outgoing_generic.go
+++ b/streams_map_outgoing_generic.go
@@ -19,6 +19,7 @@ type outgoingItemsMap struct {
 
 	nextStream     protocol.StreamID // stream ID of the stream returned by OpenStream(Sync)
 	maxStream      protocol.StreamID // the maximum stream ID we're allowed to open
+	maxStreamSet   bool              // was maxStream set. If not, it's not possible to any stream (also works for stream 0)
 	highestBlocked protocol.StreamID // the highest stream ID that we queued a STREAM_ID_BLOCKED frame for
 
 	newStream            func(protocol.StreamID) item
@@ -69,7 +70,7 @@ func (m *outgoingItemsMap) openStreamImpl() (item, error) {
 	if m.closeErr != nil {
 		return nil, m.closeErr
 	}
-	if m.nextStream > m.maxStream {
+	if !m.maxStreamSet || m.nextStream > m.maxStream {
 		if m.maxStream == 0 || m.highestBlocked < m.maxStream {
 			m.queueStreamIDBlocked(&wire.StreamIDBlockedFrame{StreamID: m.maxStream})
 			m.highestBlocked = m.maxStream
@@ -106,8 +107,9 @@ func (m *outgoingItemsMap) DeleteStream(id protocol.StreamID) error {
 
 func (m *outgoingItemsMap) SetMaxStream(id protocol.StreamID) {
 	m.mutex.Lock()
-	if id > m.maxStream {
+	if !m.maxStreamSet || id > m.maxStream {
 		m.maxStream = id
+		m.maxStreamSet = true
 		m.cond.Broadcast()
 	}
 	m.mutex.Unlock()
diff --git a/streams_map_outgoing_generic_test.go b/streams_map_outgoing_generic_test.go
index c8426899..231f8cfe 100644
--- a/streams_map_outgoing_generic_test.go
+++ b/streams_map_outgoing_generic_test.go
@@ -122,6 +122,23 @@ var _ = Describe("Streams Map (outgoing)", func() {
 			Eventually(done).Should(BeClosed())
 		})
 
+		It("works with stream 0", func() {
+			m = newOutgoingItemsMap(0, newItem, mockSender.queueControlFrame)
+			mockSender.EXPECT().queueControlFrame(&wire.StreamIDBlockedFrame{StreamID: 0})
+			done := make(chan struct{})
+			go func() {
+				defer GinkgoRecover()
+				str, err := m.OpenStreamSync()
+				Expect(err).ToNot(HaveOccurred())
+				Expect(str.(*mockGenericStream).id).To(BeZero())
+				close(done)
+			}()
+
+			Consistently(done).ShouldNot(BeClosed())
+			m.SetMaxStream(0)
+			Eventually(done).Should(BeClosed())
+		})
+
 		It("stops opening synchronously when it is closed", func() {
 			mockSender.EXPECT().queueControlFrame(gomock.Any())
 			testErr := errors.New("test error")
diff --git a/streams_map_outgoing_uni.go b/streams_map_outgoing_uni.go
index 6ad0348c..34243887 100644
--- a/streams_map_outgoing_uni.go
+++ b/streams_map_outgoing_uni.go
@@ -21,6 +21,7 @@ type outgoingUniStreamsMap struct {
 
 	nextStream     protocol.StreamID // stream ID of the stream returned by OpenStream(Sync)
 	maxStream      protocol.StreamID // the maximum stream ID we're allowed to open
+	maxStreamSet   bool              // was maxStream set. If not, it's not possible to any stream (also works for stream 0)
 	highestBlocked protocol.StreamID // the highest stream ID that we queued a STREAM_ID_BLOCKED frame for
 
 	newStream            func(protocol.StreamID) sendStreamI
@@ -71,7 +72,7 @@ func (m *outgoingUniStreamsMap) openStreamImpl() (sendStreamI, error) {
 	if m.closeErr != nil {
 		return nil, m.closeErr
 	}
-	if m.nextStream > m.maxStream {
+	if !m.maxStreamSet || m.nextStream > m.maxStream {
 		if m.maxStream == 0 || m.highestBlocked < m.maxStream {
 			m.queueStreamIDBlocked(&wire.StreamIDBlockedFrame{StreamID: m.maxStream})
 			m.highestBlocked = m.maxStream
@@ -108,8 +109,9 @@ func (m *outgoingUniStreamsMap) DeleteStream(id protocol.StreamID) error {
 
 func (m *outgoingUniStreamsMap) SetMaxStream(id protocol.StreamID) {
 	m.mutex.Lock()
-	if id > m.maxStream {
+	if !m.maxStreamSet || id > m.maxStream {
 		m.maxStream = id
+		m.maxStreamSet = true
 		m.cond.Broadcast()
 	}
 	m.mutex.Unlock()