From 7604f7927d6fb942c28ab69d1b2cfa7054068ee7 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Fri, 29 Jul 2016 18:00:05 +0700
Subject: [PATCH] send a StopWaiting with every ACK in QUIC 34

fixes #185
---
 ackhandler/interfaces.go                |  3 +++
 ackhandler/sent_packet_handler.go       | 10 ++++++++++
 ackhandler/sent_packet_handler_test.go  | 11 +++++++++++
 ackhandlerlegacy/interfaces.go          |  2 ++
 ackhandlerlegacy/sent_packet_handler.go |  4 ++++
 session.go                              |  4 ++++
 session_test.go                         |  9 ++++++---
 7 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/ackhandler/interfaces.go b/ackhandler/interfaces.go
index 1999b4c4..414c4787 100644
--- a/ackhandler/interfaces.go
+++ b/ackhandler/interfaces.go
@@ -13,6 +13,8 @@ type SentPacketHandler interface {
 	SentPacket(packet *ackhandlerlegacy.Packet) error
 	ReceivedAck(ackFrame *frames.AckFrame, withPacketNumber protocol.PacketNumber) error
 
+	GetStopWaitingFrame() *frames.StopWaitingFrame
+
 	ProbablyHasPacketForRetransmission() bool
 	DequeuePacketForRetransmission() (packet *ackhandlerlegacy.Packet)
 
@@ -35,6 +37,7 @@ type ReceivedPacketHandler interface {
 }
 
 // StopWaitingManager manages StopWaitings for sent packets
+// TODO: remove once we drop support for QUIC 33
 type StopWaitingManager interface {
 	RegisterPacketForRetransmission(packet *ackhandlerlegacy.Packet)
 	GetStopWaitingFrame() *frames.StopWaitingFrame
diff --git a/ackhandler/sent_packet_handler.go b/ackhandler/sent_packet_handler.go
index 0c248a05..935313e6 100644
--- a/ackhandler/sent_packet_handler.go
+++ b/ackhandler/sent_packet_handler.go
@@ -272,6 +272,16 @@ func (h *sentPacketHandler) GetLargestAcked() protocol.PacketNumber {
 	return h.LargestAcked
 }
 
+func (h *sentPacketHandler) GetStopWaitingFrame() *frames.StopWaitingFrame {
+	if h.LargestAcked == 0 {
+		return nil
+	}
+
+	return &frames.StopWaitingFrame{
+		LeastUnacked: h.LargestAcked + 1,
+	}
+}
+
 func (h *sentPacketHandler) CongestionAllowsSending() bool {
 	return h.BytesInFlight() <= h.congestion.GetCongestionWindow()
 }
diff --git a/ackhandler/sent_packet_handler_test.go b/ackhandler/sent_packet_handler_test.go
index ea661516..e9492461 100644
--- a/ackhandler/sent_packet_handler_test.go
+++ b/ackhandler/sent_packet_handler_test.go
@@ -350,6 +350,17 @@ var _ = Describe("SentPacketHandler", func() {
 			})
 		})
 
+		Context("StopWaitings", func() {
+			It("does not get a StopWaiting if no ACKs haven't been received yet", func() {
+				Expect(handler.GetStopWaitingFrame()).To(BeNil())
+			})
+
+			It("gets a StopWaitingFrame", func() {
+				handler.LargestAcked = 1336
+				Expect(handler.GetStopWaitingFrame()).To(Equal(&frames.StopWaitingFrame{LeastUnacked: 1337}))
+			})
+		})
+
 		Context("calculating RTT", func() {
 			It("calculates the RTT", func() {
 				now := time.Now()
diff --git a/ackhandlerlegacy/interfaces.go b/ackhandlerlegacy/interfaces.go
index 45d5be5b..0c7253a2 100644
--- a/ackhandlerlegacy/interfaces.go
+++ b/ackhandlerlegacy/interfaces.go
@@ -12,6 +12,8 @@ type SentPacketHandler interface {
 	SentPacket(packet *Packet) error
 	ReceivedAck(ackFrame *frames.AckFrame, withPacketNumber protocol.PacketNumber) error
 
+	GetStopWaitingFrame() *frames.StopWaitingFrame
+
 	ProbablyHasPacketForRetransmission() bool
 	DequeuePacketForRetransmission() (packet *Packet)
 
diff --git a/ackhandlerlegacy/sent_packet_handler.go b/ackhandlerlegacy/sent_packet_handler.go
index 8cdde14c..d609ec85 100644
--- a/ackhandlerlegacy/sent_packet_handler.go
+++ b/ackhandlerlegacy/sent_packet_handler.go
@@ -312,6 +312,10 @@ func (h *sentPacketHandler) GetLargestAcked() protocol.PacketNumber {
 	return h.LargestObserved
 }
 
+func (h *sentPacketHandler) GetStopWaitingFrame() *frames.StopWaitingFrame {
+	panic("Legacy AckHandler should use StopWaitingManager")
+}
+
 func (h *sentPacketHandler) CongestionAllowsSending() bool {
 	return h.BytesInFlight() <= h.congestion.GetCongestionWindow()
 }
diff --git a/session.go b/session.go
index 63b42e8f..4c52cce2 100644
--- a/session.go
+++ b/session.go
@@ -513,6 +513,10 @@ func (s *Session) sendPacket() error {
 		var stopWaitingFrame *frames.StopWaitingFrame
 		if s.version <= protocol.Version33 {
 			stopWaitingFrame = s.stopWaitingManager.GetStopWaitingFrame()
+		} else {
+			if ack != nil {
+				stopWaitingFrame = s.sentPacketHandler.GetStopWaitingFrame()
+			}
 		}
 		packet, err := s.packer.PackPacket(stopWaitingFrame, controlFrames, s.sentPacketHandler.GetLargestAcked(), maySendOnlyAck)
 		if err != nil {
diff --git a/session_test.go b/session_test.go
index 42ba531d..c06f99ee 100644
--- a/session_test.go
+++ b/session_test.go
@@ -56,9 +56,12 @@ func (h *mockSentPacketHandler) ReceivedAck(ackFrame *frames.AckFrame, withPacke
 }
 func (h *mockSentPacketHandler) BytesInFlight() protocol.ByteCount      { return 0 }
 func (h *mockSentPacketHandler) GetLargestAcked() protocol.PacketNumber { return 1 }
-func (h *mockSentPacketHandler) CongestionAllowsSending() bool          { return true }
-func (h *mockSentPacketHandler) CheckForError() error                   { return nil }
-func (h *mockSentPacketHandler) TimeOfFirstRTO() time.Time              { panic("not implemented") }
+func (h *mockSentPacketHandler) GetStopWaitingFrame() *frames.StopWaitingFrame {
+	panic("not implemented")
+}
+func (h *mockSentPacketHandler) CongestionAllowsSending() bool { return true }
+func (h *mockSentPacketHandler) CheckForError() error          { return nil }
+func (h *mockSentPacketHandler) TimeOfFirstRTO() time.Time     { panic("not implemented") }
 
 func (h *mockSentPacketHandler) ProbablyHasPacketForRetransmission() bool {
 	return len(h.retransmissionQueue) > 0