account for the size of the header when packing 1-RTT probe packets

Author: marten-seemann

packet_packer.go

@@ -467,7 +467,7 @@ func (p *packetPacker) PackPacket() (*packedPacket, error) {
 	}, nil
 }
 
-func (p *packetPacker) maybeGetCryptoPacket(maxSize, currentSize protocol.ByteCount, encLevel protocol.EncryptionLevel) (*wire.ExtendedHeader, *payload) {
+func (p *packetPacker) maybeGetCryptoPacket(maxPacketSize, currentSize protocol.ByteCount, encLevel protocol.EncryptionLevel) (*wire.ExtendedHeader, *payload) {
 	var s cryptoStream
 	var hasRetransmission bool
 	//nolint:exhaustive // Initial and Handshake are the only two encryption levels here.
@@ -494,30 +494,30 @@ func (p *packetPacker) maybeGetCryptoPacket(maxSize, currentSize protocol.ByteCo
 	if ack != nil {
 		payload.ack = ack
 		payload.length = ack.Length(p.version)
-		maxSize -= payload.length
+		maxPacketSize -= payload.length
 	}
 	hdr := p.getLongHeader(encLevel)
-	maxSize -= hdr.GetLength(p.version)
+	maxPacketSize -= hdr.GetLength(p.version)
 	if hasRetransmission {
 		for {
 			var f wire.Frame
 			//nolint:exhaustive // 0-RTT packets can't contain any retransmission.s
 			switch encLevel {
 			case protocol.EncryptionInitial:
-				f = p.retransmissionQueue.GetInitialFrame(maxSize)
+				f = p.retransmissionQueue.GetInitialFrame(maxPacketSize)
 			case protocol.EncryptionHandshake:
-				f = p.retransmissionQueue.GetHandshakeFrame(maxSize)
+				f = p.retransmissionQueue.GetHandshakeFrame(maxPacketSize)
 			}
 			if f == nil {
 				break
 			}
 			payload.frames = append(payload.frames, ackhandler.Frame{Frame: f})
 			frameLen := f.Length(p.version)
 			payload.length += frameLen
-			maxSize -= frameLen
+			maxPacketSize -= frameLen
 		}
 	} else if s.HasData() {
-		cf := s.PopCryptoFrame(maxSize)
+		cf := s.PopCryptoFrame(maxPacketSize)
 		payload.frames = []ackhandler.Frame{{Frame: cf}}
 		payload.length += cf.Length(p.version)
 	}
@@ -547,18 +547,19 @@ func (p *packetPacker) maybeGetAppDataPacket(maxPacketSize, currentSize protocol
 	}
 
 	maxPayloadSize := maxPacketSize - hdr.GetLength(p.version) - protocol.ByteCount(sealer.Overhead())
-	payload := p.maybeGetAppDataPacketWithEncLevel(maxPayloadSize, currentSize, encLevel)
+	payload := p.maybeGetAppDataPacketWithEncLevel(maxPayloadSize, encLevel == protocol.Encryption1RTT && currentSize == 0)
 	return sealer, hdr, payload
 }
 
-func (p *packetPacker) maybeGetAppDataPacketWithEncLevel(maxPayloadSize, currentSize protocol.ByteCount, encLevel protocol.EncryptionLevel) *payload {
-	payload := p.composeNextPacket(maxPayloadSize, encLevel == protocol.Encryption1RTT && currentSize == 0)
+func (p *packetPacker) maybeGetAppDataPacketWithEncLevel(maxPayloadSize protocol.ByteCount, ackAllowed bool) *payload {
+	payload := p.composeNextPacket(maxPayloadSize, ackAllowed)
 
 	// check if we have anything to send
-	if len(payload.frames) == 0 && payload.ack == nil {
-		return nil
-	}
-	if len(payload.frames) == 0 { // the packet only contains an ACK
+	if len(payload.frames) == 0 {
+		if payload.ack == nil {
+			return nil
+		}
+		// the packet only contains an ACK
 		if p.numNonAckElicitingAcks >= protocol.MaxNonAckElicitingAcks {
 			ping := &wire.PingFrame{}
 			payload.frames = append(payload.frames, ackhandler.Frame{Frame: ping})
@@ -642,14 +643,12 @@ func (p *packetPacker) MaybePackProbePacket(encLevel protocol.EncryptionLevel) (
 			return nil, err
 		}
 		sealer = oneRTTSealer
-		payload = p.maybeGetAppDataPacketWithEncLevel(p.maxPacketSize-protocol.ByteCount(sealer.Overhead()), 0, protocol.Encryption1RTT)
-		if payload != nil {
-			hdr = p.getShortHeader(oneRTTSealer.KeyPhase())
-		}
+		hdr = p.getShortHeader(oneRTTSealer.KeyPhase())
+		payload = p.maybeGetAppDataPacketWithEncLevel(p.maxPacketSize-protocol.ByteCount(sealer.Overhead())-hdr.GetLength(p.version), true)
 	default:
 		panic("unknown encryption level")
 	}
-	if hdr == nil {
+	if payload == nil {
 		return nil, nil
 	}
 	size := p.packetLength(hdr, payload) + protocol.ByteCount(sealer.Overhead())

packet_packer_test.go

@@ -1322,6 +1322,25 @@ var _ = Describe("Packet packer", func() {
 				parsePacket(packet.buffer.Data)
 			})
 
+			It("packs a full size  Handshake probe packet", func() {
+				f := &wire.CryptoFrame{Data: make([]byte, 2000)}
+				retransmissionQueue.AddHandshake(f)
+				sealingManager.EXPECT().GetHandshakeSealer().Return(getSealer(), nil)
+				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake, false)
+				handshakeStream.EXPECT().HasData()
+				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
+				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42))
+
+				packet, err := packer.MaybePackProbePacket(protocol.EncryptionHandshake)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(packet).ToNot(BeNil())
+				Expect(packet.EncryptionLevel()).To(Equal(protocol.EncryptionHandshake))
+				Expect(packet.frames).To(HaveLen(1))
+				Expect(packet.frames[0].Frame).To(BeAssignableToTypeOf(&wire.CryptoFrame{}))
+				Expect(packet.length).To(Equal(maxPacketSize))
+				parsePacket(packet.buffer.Data)
+			})
+
 			It("packs a 1-RTT probe packet", func() {
 				f := &wire.StreamFrame{Data: []byte("1-RTT")}
 				retransmissionQueue.AddInitial(f)
@@ -1341,8 +1360,33 @@ var _ = Describe("Packet packer", func() {
 				Expect(packet.frames[0].Frame).To(Equal(f))
 			})
 
+			It("packs a full size 1-RTT probe packet", func() {
+				f := &wire.StreamFrame{Data: make([]byte, 2000)}
+				retransmissionQueue.AddInitial(f)
+				sealingManager.EXPECT().Get1RTTSealer().Return(getSealer(), nil)
+				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT, false)
+				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
+				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
+				framer.EXPECT().HasData().Return(true)
+				expectAppendControlFrames()
+				framer.EXPECT().AppendStreamFrames(gomock.Any(), gomock.Any()).DoAndReturn(func(fs []ackhandler.Frame, maxSize protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
+					sf, split := f.MaybeSplitOffFrame(maxSize, packer.version)
+					Expect(split).To(BeTrue())
+					return append(fs, ackhandler.Frame{Frame: sf}), sf.Length(packer.version)
+				})
+
+				packet, err := packer.MaybePackProbePacket(protocol.Encryption1RTT)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(packet).ToNot(BeNil())
+				Expect(packet.EncryptionLevel()).To(Equal(protocol.Encryption1RTT))
+				Expect(packet.frames).To(HaveLen(1))
+				Expect(packet.frames[0].Frame).To(BeAssignableToTypeOf(&wire.StreamFrame{}))
+				Expect(packet.length).To(Equal(maxPacketSize))
+			})
+
 			It("returns nil if there's no probe data to send", func() {
 				sealingManager.EXPECT().Get1RTTSealer().Return(getSealer(), nil)
+				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
 				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT, true)
 				framer.EXPECT().HasData()