From d76d86a7e1be55cc02a681af45fa5a1a6e35c310 Mon Sep 17 00:00:00 2001
From: Lucas Clemente <lucas@clemente.io>
Date: Thu, 1 Sep 2016 20:09:41 +0200
Subject: [PATCH] fix detection of only-ack packets

ref #315
---
 packet_packer.go      | 4 ++--
 packet_packer_test.go | 6 +++---
 session.go            | 4 ++++
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/packet_packer.go b/packet_packer.go
index 9c18aa63..5d96737b 100644
--- a/packet_packer.go
+++ b/packet_packer.go
@@ -113,11 +113,11 @@ func (p *packetPacker) packPacket(stopWaitingFrame *frames.StopWaitingFrame, con
 	// Don't send out packets that only contain an ACK (plus optional STOP_WAITING), if requested
 	if !maySendOnlyAck {
 		if len(payloadFrames) == 1 {
-			if _, ok := payloadFrames[0].(*frames.AckFrameLegacy); ok {
+			if _, ok := payloadFrames[0].(*frames.AckFrame); ok {
 				return nil, nil
 			}
 		} else if len(payloadFrames) == 2 && stopWaitingFrame != nil {
-			if _, ok := payloadFrames[1].(*frames.AckFrameLegacy); ok {
+			if _, ok := payloadFrames[1].(*frames.AckFrame); ok {
 				return nil, nil
 			}
 		}
diff --git a/packet_packer_test.go b/packet_packer_test.go
index 06b4d96c..28d71d70 100644
--- a/packet_packer_test.go
+++ b/packet_packer_test.go
@@ -464,19 +464,19 @@ var _ = Describe("Packet packer", func() {
 	})
 
 	It("returns nil if we only have a single STOP_WAITING and an ACK", func() {
-		p, err := packer.PackPacket(&frames.StopWaitingFrame{}, []frames.Frame{&frames.AckFrameLegacy{}}, 0, false)
+		p, err := packer.PackPacket(&frames.StopWaitingFrame{}, []frames.Frame{&frames.AckFrame{}}, 0, false)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(p).To(BeNil())
 	})
 
 	It("returns nil if we only have a single ACK", func() {
-		p, err := packer.PackPacket(nil, []frames.Frame{&frames.AckFrameLegacy{}}, 0, false)
+		p, err := packer.PackPacket(nil, []frames.Frame{&frames.AckFrame{}}, 0, false)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(p).To(BeNil())
 	})
 
 	It("does not return nil if we only have a single ACK but request it to be sent", func() {
-		p, err := packer.PackPacket(nil, []frames.Frame{&frames.AckFrameLegacy{}}, 0, true)
+		p, err := packer.PackPacket(nil, []frames.Frame{&frames.AckFrame{}}, 0, true)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(p).ToNot(BeNil())
 	})
diff --git a/session.go b/session.go
index f8c0448b..f113dd0b 100644
--- a/session.go
+++ b/session.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"runtime"
 	"sync/atomic"
 	"time"
 
@@ -490,6 +491,9 @@ func (s *Session) sendPacket() error {
 
 		// Check whether we are allowed to send a packet containing only an ACK
 		maySendOnlyAck := time.Now().Sub(s.delayedAckOriginTime) > protocol.AckSendDelay
+		if runtime.GOOS == "windows" {
+			maySendOnlyAck = true
+		}
 
 		hasRetransmission := s.streamFramer.HasFramesForRetransmission()