From e470d71c3a4ef716f114a07edbb4975f3183b685 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 29 Oct 2018 13:34:32 +0700
Subject: [PATCH] add ACK frames to crypto packets

---
 packet_packer.go      |  7 ++++++-
 packet_packer_test.go | 26 +++++++++++++++++++++++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/packet_packer.go b/packet_packer.go
index afde1d91e..f7e75ad58 100644
--- a/packet_packer.go
+++ b/packet_packer.go
@@ -343,8 +343,13 @@ func (p *packetPacker) maybePackCryptoPacket() (*packedPacket, error) {
 		return nil, err
 	}
 	var length protocol.ByteCount
+	frames := make([]wire.Frame, 0, 2)
+	if ack := p.acks.GetAckFrame(); ack != nil {
+		frames = append(frames, ack)
+		length += ack.Length(p.version)
+	}
 	cf := s.PopCryptoFrame(p.maxPacketSize - hdrLen - protocol.ByteCount(sealer.Overhead()) - length)
-	frames := []wire.Frame{cf}
+	frames = append(frames, cf)
 	raw, err := p.writeAndSealPacket(hdr, frames, sealer)
 	if err != nil {
 		return nil, err
diff --git a/packet_packer_test.go b/packet_packer_test.go
index b70a77a5a..5a707b3eb 100644
--- a/packet_packer_test.go
+++ b/packet_packer_test.go
@@ -664,6 +664,7 @@ var _ = Describe("Packet packer", func() {
 				Offset: 0x1337,
 				Data:   []byte("foobar"),
 			}
+			ackFramer.EXPECT().GetAckFrame()
 			initialStream.EXPECT().HasData().Return(true)
 			initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
 			sealingManager.EXPECT().GetSealerWithEncryptionLevel(protocol.EncryptionInitial).Return(sealer, nil)
@@ -676,6 +677,7 @@ var _ = Describe("Packet packer", func() {
 			var f *wire.CryptoFrame
 			packer.version = versionIETFFrames
 			sealingManager.EXPECT().GetSealerWithEncryptionLevel(protocol.EncryptionHandshake).Return(sealer, nil)
+			ackFramer.EXPECT().GetAckFrame()
 			initialStream.EXPECT().HasData()
 			handshakeStream.EXPECT().HasData().Return(true)
 			handshakeStream.EXPECT().PopCryptoFrame(gomock.Any()).DoAndReturn(func(size protocol.ByteCount) *wire.CryptoFrame {
@@ -694,10 +696,9 @@ var _ = Describe("Packet packer", func() {
 		})
 
 		It("pads Initial packets to the required minimum packet size", func() {
-			f := &wire.CryptoFrame{
-				Data: []byte("foobar"),
-			}
+			f := &wire.CryptoFrame{Data: []byte("foobar")}
 			sealingManager.EXPECT().GetSealerWithEncryptionLevel(protocol.EncryptionInitial).Return(sealer, nil)
+			ackFramer.EXPECT().GetAckFrame()
 			initialStream.EXPECT().HasData().Return(true)
 			initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
 			packer.version = protocol.VersionTLS
@@ -714,6 +715,7 @@ var _ = Describe("Packet packer", func() {
 
 		It("sets the correct payload length for an Initial packet", func() {
 			sealingManager.EXPECT().GetSealerWithEncryptionLevel(protocol.EncryptionInitial).Return(sealer, nil)
+			ackFramer.EXPECT().GetAckFrame()
 			initialStream.EXPECT().HasData().Return(true)
 			initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(&wire.CryptoFrame{
 				Data: []byte("foobar"),
@@ -725,6 +727,24 @@ var _ = Describe("Packet packer", func() {
 			checkPayloadLen(packet.raw)
 		})
 
+		It("adds an ACK frame", func() {
+			f := &wire.CryptoFrame{Data: []byte("foobar")}
+			ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 42, Largest: 1337}}}
+			sealingManager.EXPECT().GetSealerWithEncryptionLevel(protocol.EncryptionInitial).Return(sealer, nil)
+			ackFramer.EXPECT().GetAckFrame().Return(ack)
+			initialStream.EXPECT().HasData().Return(true)
+			initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
+			packer.version = protocol.VersionTLS
+			packer.hasSentPacket = false
+			packer.perspective = protocol.PerspectiveClient
+			packet, err := packer.PackPacket()
+			Expect(err).ToNot(HaveOccurred())
+			Expect(packet.header.Token).To(Equal(token))
+			Expect(packet.raw).To(HaveLen(protocol.MinInitialPacketSize))
+			Expect(packet.frames).To(HaveLen(2))
+			Expect(packet.frames[0]).To(Equal(ack))
+		})
+
 		Context("retransmitions", func() {
 			sf := &wire.StreamFrame{Data: []byte("foobar")}