package quic

import (
	"bytes"
	"errors"
	"math/rand"
	"net"
	"time"

	"github.com/lucas-clemente/quic-go/internal/ackhandler"

	"github.com/golang/mock/gomock"
	"github.com/lucas-clemente/quic-go/internal/handshake"
	"github.com/lucas-clemente/quic-go/internal/mocks"
	mockackhandler "github.com/lucas-clemente/quic-go/internal/mocks/ackhandler"
	"github.com/lucas-clemente/quic-go/internal/protocol"
	"github.com/lucas-clemente/quic-go/internal/wire"
	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
)

var _ = Describe("Packet packer", func() {
	const maxPacketSize protocol.ByteCount = 1357
	const version = protocol.VersionTLS

	var (
		packer              *packetPacker
		retransmissionQueue *retransmissionQueue
		framer              *MockFrameSource
		ackFramer           *MockAckFrameSource
		initialStream       *MockCryptoStream
		handshakeStream     *MockCryptoStream
		sealingManager      *MockSealingManager
		pnManager           *mockackhandler.MockSentPacketHandler
	)

	checkLength := func(data []byte) {
		hdr, _, _, err := wire.ParsePacket(data, 0)
		Expect(err).ToNot(HaveOccurred())
		r := bytes.NewReader(data)
		extHdr, err := hdr.ParseExtended(r, version)
		Expect(err).ToNot(HaveOccurred())
		ExpectWithOffset(1, extHdr.Length).To(BeEquivalentTo(r.Len() + int(extHdr.PacketNumberLen)))
	}

	appendFrames := func(fs, frames []ackhandler.Frame) ([]ackhandler.Frame, protocol.ByteCount) {
		var length protocol.ByteCount
		for _, f := range frames {
			length += f.Frame.Length(packer.version)
		}
		return append(fs, frames...), length
	}

	expectAppendStreamFrames := func(frames ...ackhandler.Frame) {
		framer.EXPECT().AppendStreamFrames(gomock.Any(), gomock.Any()).DoAndReturn(func(fs []ackhandler.Frame, _ protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
			return appendFrames(fs, frames)
		})
	}

	expectAppendControlFrames := func(frames ...ackhandler.Frame) {
		framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).DoAndReturn(func(fs []ackhandler.Frame, _ protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
			return appendFrames(fs, frames)
		})
	}

	BeforeEach(func() {
		rand.Seed(GinkgoRandomSeed())
		retransmissionQueue = newRetransmissionQueue(version)
		mockSender := NewMockStreamSender(mockCtrl)
		mockSender.EXPECT().onHasStreamData(gomock.Any()).AnyTimes()
		initialStream = NewMockCryptoStream(mockCtrl)
		handshakeStream = NewMockCryptoStream(mockCtrl)
		framer = NewMockFrameSource(mockCtrl)
		ackFramer = NewMockAckFrameSource(mockCtrl)
		sealingManager = NewMockSealingManager(mockCtrl)
		pnManager = mockackhandler.NewMockSentPacketHandler(mockCtrl)

		packer = newPacketPacker(
			protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8},
			func() protocol.ConnectionID { return protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8} },
			initialStream,
			handshakeStream,
			pnManager,
			retransmissionQueue,
			&net.TCPAddr{},
			sealingManager,
			framer,
			ackFramer,
			protocol.PerspectiveServer,
			version,
		)
		packer.version = version
		packer.maxPacketSize = maxPacketSize
	})

	Context("determining the maximum packet size", func() {
		It("uses the minimum initial size, if it can't determine if the remote address is IPv4 or IPv6", func() {
			Expect(getMaxPacketSize(&net.TCPAddr{})).To(BeEquivalentTo(protocol.MinInitialPacketSize))
		})

		It("uses the maximum IPv4 packet size, if the remote address is IPv4", func() {
			addr := &net.UDPAddr{IP: net.IPv4(11, 12, 13, 14), Port: 1337}
			Expect(getMaxPacketSize(addr)).To(BeEquivalentTo(protocol.MaxPacketSizeIPv4))
		})

		It("uses the maximum IPv6 packet size, if the remote address is IPv6", func() {
			ip := net.ParseIP("2001:0db8:85a3:0000:0000:8a2e:0370:7334")
			addr := &net.UDPAddr{IP: ip, Port: 1337}
			Expect(getMaxPacketSize(addr)).To(BeEquivalentTo(protocol.MaxPacketSizeIPv6))
		})
	})

	Context("generating a packet header", func() {
		It("uses the Long Header format", func() {
			pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
			h := packer.getLongHeader(protocol.EncryptionHandshake)
			Expect(h.IsLongHeader).To(BeTrue())
			Expect(h.PacketNumber).To(Equal(protocol.PacketNumber(0x42)))
			// long headers always use 4 byte packet numbers, no matter what the packet number generator says
			Expect(h.PacketNumberLen).To(Equal(protocol.PacketNumberLen4))
			Expect(h.Version).To(Equal(packer.version))
		})

		It("sets source and destination connection ID", func() {
			pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
			srcConnID := protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8}
			destConnID := protocol.ConnectionID{8, 7, 6, 5, 4, 3, 2, 1}
			packer.srcConnID = srcConnID
			packer.getDestConnID = func() protocol.ConnectionID { return destConnID }
			h := packer.getLongHeader(protocol.EncryptionHandshake)
			Expect(h.SrcConnectionID).To(Equal(srcConnID))
			Expect(h.DestConnectionID).To(Equal(destConnID))
		})

		It("gets a short header", func() {
			pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x1337), protocol.PacketNumberLen4)
			h := packer.getShortHeader(protocol.KeyPhaseOne)
			Expect(h.IsLongHeader).To(BeFalse())
			Expect(h.PacketNumber).To(Equal(protocol.PacketNumber(0x1337)))
			Expect(h.PacketNumberLen).To(Equal(protocol.PacketNumberLen4))
			Expect(h.KeyPhase).To(Equal(protocol.KeyPhaseOne))
		})
	})

	Context("encrypting packets", func() {
		It("encrypts a packet", func() {
			initialStream.EXPECT().HasData()
			handshakeStream.EXPECT().HasData()
			pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x1337), protocol.PacketNumberLen2)
			pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x1337))
			sealer := mocks.NewMockShortHeaderSealer(mockCtrl)
			sealer.EXPECT().Overhead().Return(4).AnyTimes()
			var hdrRaw []byte
			gomock.InOrder(
				sealer.EXPECT().KeyPhase().Return(protocol.KeyPhaseOne),
				sealer.EXPECT().Seal(gomock.Any(), gomock.Any(), protocol.PacketNumber(0x1337), gomock.Any()).DoAndReturn(func(_, src []byte, _ protocol.PacketNumber, aad []byte) []byte {
					hdrRaw = append([]byte{}, aad...)
					return append(src, []byte{0xde, 0xca, 0xfb, 0xad}...)
				}),
				sealer.EXPECT().EncryptHeader(gomock.Any(), gomock.Any(), gomock.Any()).Do(func(sample []byte, firstByte *byte, pnBytes []byte) {
					Expect(firstByte).To(Equal(&hdrRaw[0]))
					Expect(pnBytes).To(Equal(hdrRaw[len(hdrRaw)-2:]))
					*firstByte ^= 0xff // invert the first byte
					// invert the packet number bytes
					for i := range pnBytes {
						pnBytes[i] ^= 0xff
					}
				}),
			)
			sealingManager.EXPECT().GetInitialSealer().Return(nil, nil)
			sealingManager.EXPECT().GetHandshakeSealer().Return(nil, nil)
			sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
			ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
			ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake)
			ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
			expectAppendControlFrames()
			f := &wire.StreamFrame{Data: []byte{0xde, 0xca, 0xfb, 0xad}}
			expectAppendStreamFrames(ackhandler.Frame{Frame: f})
			p, err := packer.PackPacket()
			Expect(err).ToNot(HaveOccurred())
			Expect(p).ToNot(BeNil())
			Expect(p.frames).To(Equal([]ackhandler.Frame{{Frame: f}}))
			hdrRawEncrypted := append([]byte{}, hdrRaw...)
			hdrRawEncrypted[0] ^= 0xff
			hdrRawEncrypted[len(hdrRaw)-2] ^= 0xff
			hdrRawEncrypted[len(hdrRaw)-1] ^= 0xff
			Expect(p.raw[0:len(hdrRaw)]).To(Equal(hdrRawEncrypted))
			Expect(p.raw[len(p.raw)-4:]).To(Equal([]byte{0xde, 0xca, 0xfb, 0xad}))
		})
	})

	Context("packing packets", func() {
		var sealer *mocks.MockShortHeaderSealer

		BeforeEach(func() {
			sealer = mocks.NewMockShortHeaderSealer(mockCtrl)
			sealer.EXPECT().KeyPhase().Return(protocol.KeyPhaseOne).AnyTimes()
			sealer.EXPECT().Overhead().Return(7).AnyTimes()
			sealer.EXPECT().EncryptHeader(gomock.Any(), gomock.Any(), gomock.Any()).AnyTimes()
			sealer.EXPECT().Seal(gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any()).DoAndReturn(func(dst, src []byte, pn protocol.PacketNumber, associatedData []byte) []byte {
				return append(src, bytes.Repeat([]byte{0}, sealer.Overhead())...)
			}).AnyTimes()
		})

		Context("packing ACK packets", func() {
			It("doesn't pack a packet if there's no ACK to send", func() {
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				p, err := packer.MaybePackAckPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p).To(BeNil())
			})

			It("packs Handshake ACK-only packets", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetHandshakeSealer().Return(sealer, nil)
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 10}}}
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake).Return(ack)
				p, err := packer.MaybePackAckPacket()
				Expect(err).NotTo(HaveOccurred())
				Expect(p).ToNot(BeNil())
				Expect(p.EncryptionLevel()).To(Equal(protocol.EncryptionHandshake))
				Expect(p.ack).To(Equal(ack))
			})

			It("packs 1-RTT ACK-only packets", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 10}}}
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(ack)
				p, err := packer.MaybePackAckPacket()
				Expect(err).NotTo(HaveOccurred())
				Expect(p).ToNot(BeNil())
				Expect(p.EncryptionLevel()).To(Equal(protocol.Encryption1RTT))
				Expect(p.ack).To(Equal(ack))
			})
		})

		Context("packing normal packets", func() {
			BeforeEach(func() {
				sealingManager.EXPECT().GetInitialSealer().Return(nil, nil).AnyTimes()
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, nil).AnyTimes()
				initialStream.EXPECT().HasData().AnyTimes()
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial).AnyTimes()
				handshakeStream.EXPECT().HasData().AnyTimes()
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake).AnyTimes()
			})

			It("returns nil when no packet is queued", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				// don't expect any calls to PopPacketNumber
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				framer.EXPECT().AppendControlFrames(nil, gomock.Any())
				framer.EXPECT().AppendStreamFrames(nil, gomock.Any())
				p, err := packer.PackPacket()
				Expect(p).To(BeNil())
				Expect(err).ToNot(HaveOccurred())
			})

			It("packs single packets", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames()
				f := &wire.StreamFrame{
					StreamID: 5,
					Data:     []byte{0xde, 0xca, 0xfb, 0xad},
				}
				expectAppendStreamFrames(ackhandler.Frame{Frame: f})
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p).ToNot(BeNil())
				b := &bytes.Buffer{}
				f.Write(b, packer.version)
				Expect(p.frames).To(Equal([]ackhandler.Frame{{Frame: f}}))
				Expect(p.raw).To(ContainSubstring(b.String()))
			})

			It("stores the encryption level a packet was sealed with", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames()
				expectAppendStreamFrames(ackhandler.Frame{Frame: &wire.StreamFrame{
					StreamID: 5,
					Data:     []byte("foobar"),
				}})
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p.EncryptionLevel()).To(Equal(protocol.Encryption1RTT))
			})

			It("packs a single ACK", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Largest: 42, Smallest: 1}}}
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(ack)
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				expectAppendControlFrames()
				expectAppendStreamFrames()
				p, err := packer.PackPacket()
				Expect(err).NotTo(HaveOccurred())
				Expect(p).ToNot(BeNil())
				Expect(p.ack).To(Equal(ack))
			})

			It("packs a CONNECTION_CLOSE", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				// expect no framer.PopStreamFrames
				ccf := wire.ConnectionCloseFrame{
					ErrorCode:    0x1337,
					ReasonPhrase: "foobar",
				}
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				p, err := packer.PackConnectionClose(&ccf)
				Expect(err).ToNot(HaveOccurred())
				Expect(p.frames).To(HaveLen(1))
				Expect(p.frames[0].Frame).To(Equal(&ccf))
			})

			It("packs control frames", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				frames := []ackhandler.Frame{
					{Frame: &wire.ResetStreamFrame{}},
					{Frame: &wire.MaxDataFrame{}},
				}
				expectAppendControlFrames(frames...)
				expectAppendStreamFrames()
				p, err := packer.PackPacket()
				Expect(p).ToNot(BeNil())
				Expect(err).ToNot(HaveOccurred())
				Expect(p.frames).To(Equal(frames))
				Expect(p.raw).NotTo(BeEmpty())
			})

			It("accounts for the space consumed by control frames", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				var maxSize protocol.ByteCount
				gomock.InOrder(
					framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).DoAndReturn(func(fs []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						maxSize = maxLen
						return fs, 444
					}),
					framer.EXPECT().AppendStreamFrames(gomock.Any(), gomock.Any()).Do(func(fs []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						Expect(maxLen).To(Equal(maxSize - 444))
						return fs, 0
					}),
				)
				_, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
			})

			It("pads if payload length + packet number length is smaller than 4", func() {
				f := &wire.StreamFrame{
					StreamID: 0x10, // small stream ID, such that only a single byte is consumed
					FinBit:   true,
				}
				Expect(f.Length(packer.version)).To(BeEquivalentTo(2))
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen1)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames()
				expectAppendStreamFrames(ackhandler.Frame{Frame: f})
				packet, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				// cut off the tag that the mock sealer added
				packet.raw = packet.raw[:len(packet.raw)-sealer.Overhead()]
				hdr, _, _, err := wire.ParsePacket(packet.raw, len(packer.getDestConnID()))
				Expect(err).ToNot(HaveOccurred())
				r := bytes.NewReader(packet.raw)
				extHdr, err := hdr.ParseExtended(r, packer.version)
				Expect(err).ToNot(HaveOccurred())
				Expect(extHdr.PacketNumberLen).To(Equal(protocol.PacketNumberLen1))
				Expect(r.Len()).To(Equal(4 - 1 /* packet number length */))
				// the first byte of the payload should be a PADDING frame...
				firstPayloadByte, err := r.ReadByte()
				Expect(err).ToNot(HaveOccurred())
				Expect(firstPayloadByte).To(Equal(byte(0)))
				// ... followed by the STREAM frame
				frameParser := wire.NewFrameParser(packer.version)
				frame, err := frameParser.ParseNext(r, protocol.Encryption1RTT)
				Expect(err).ToNot(HaveOccurred())
				Expect(frame).To(BeAssignableToTypeOf(&wire.StreamFrame{}))
				sf := frame.(*wire.StreamFrame)
				Expect(sf.StreamID).To(Equal(f.StreamID))
				Expect(sf.FinBit).To(Equal(f.FinBit))
				Expect(sf.Data).To(BeEmpty())
				Expect(r.Len()).To(BeZero())
			})

			It("packs multiple small STREAM frames into single packet", func() {
				f1 := &wire.StreamFrame{
					StreamID:       5,
					Data:           []byte("frame 1"),
					DataLenPresent: true,
				}
				f2 := &wire.StreamFrame{
					StreamID:       5,
					Data:           []byte("frame 2"),
					DataLenPresent: true,
				}
				f3 := &wire.StreamFrame{
					StreamID:       3,
					Data:           []byte("frame 3"),
					DataLenPresent: true,
				}
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames()
				expectAppendStreamFrames(ackhandler.Frame{Frame: f1}, ackhandler.Frame{Frame: f2}, ackhandler.Frame{Frame: f3})
				p, err := packer.PackPacket()
				Expect(p).ToNot(BeNil())
				Expect(err).ToNot(HaveOccurred())
				Expect(p.frames).To(HaveLen(3))
				Expect(p.frames[0].Frame.(*wire.StreamFrame).Data).To(Equal([]byte("frame 1")))
				Expect(p.frames[1].Frame.(*wire.StreamFrame).Data).To(Equal([]byte("frame 2")))
				Expect(p.frames[2].Frame.(*wire.StreamFrame).Data).To(Equal([]byte("frame 3")))
			})

			Context("making ACK packets ack-eliciting", func() {
				sendMaxNumNonAckElicitingAcks := func() {
					for i := 0; i < protocol.MaxNonAckElicitingAcks; i++ {
						pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
						pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
						sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
						ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(&wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 1}}})
						expectAppendControlFrames()
						expectAppendStreamFrames()
						p, err := packer.PackPacket()
						Expect(p).ToNot(BeNil())
						Expect(err).ToNot(HaveOccurred())
						Expect(p.ack).ToNot(BeNil())
						Expect(p.frames).To(BeEmpty())
					}
				}

				It("adds a PING frame when it's supposed to send a ack-eliciting packet", func() {
					sendMaxNumNonAckElicitingAcks()
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
					pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(&wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 1}}})
					expectAppendControlFrames()
					expectAppendStreamFrames()
					p, err := packer.PackPacket()
					Expect(p).ToNot(BeNil())
					Expect(err).ToNot(HaveOccurred())
					Expect(p.frames).To(ContainElement(ackhandler.Frame{Frame: &wire.PingFrame{}}))
					// make sure the next packet doesn't contain another PING
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
					pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(&wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 1}}})
					expectAppendControlFrames()
					expectAppendStreamFrames()
					p, err = packer.PackPacket()
					Expect(p).ToNot(BeNil())
					Expect(err).ToNot(HaveOccurred())
					Expect(p.ack).ToNot(BeNil())
					Expect(p.frames).To(BeEmpty())
				})

				It("waits until there's something to send before adding a PING frame", func() {
					sendMaxNumNonAckElicitingAcks()
					// nothing to send
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
					expectAppendControlFrames()
					expectAppendStreamFrames()
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
					p, err := packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
					Expect(p).To(BeNil())
					// now add some frame to send
					expectAppendControlFrames()
					expectAppendStreamFrames()
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
					pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
					ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 1, Largest: 1}}}
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Return(ack)
					p, err = packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
					Expect(p.ack).To(Equal(ack))
					Expect(p.frames).To(Equal([]ackhandler.Frame{{Frame: &wire.PingFrame{}}}))
				})

				It("doesn't send a PING if it already sent another ack-eliciting frame", func() {
					sendMaxNumNonAckElicitingAcks()
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
					pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
					expectAppendStreamFrames()
					expectAppendControlFrames(ackhandler.Frame{Frame: &wire.MaxDataFrame{}})
					p, err := packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
					Expect(p).ToNot(BeNil())
					Expect(p.frames).ToNot(ContainElement(&wire.PingFrame{}))
				})
			})

			Context("max packet size", func() {
				It("sets the maximum packet size", func() {
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2).Times(2)
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil).Times(2)
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Times(2)
					var initialMaxPacketSize protocol.ByteCount
					framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).Do(func(_ []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						initialMaxPacketSize = maxLen
						return nil, 0
					})
					expectAppendStreamFrames()
					_, err := packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
					// now reduce the maxPacketSize
					packer.HandleTransportParameters(&handshake.TransportParameters{
						MaxPacketSize: maxPacketSize - 10,
					})
					framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).Do(func(_ []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						Expect(maxLen).To(Equal(initialMaxPacketSize - 10))
						return nil, 0
					})
					expectAppendStreamFrames()
					_, err = packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
				})

				It("doesn't increase the max packet size", func() {
					pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2).Times(2)
					sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil).Times(2)
					ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT).Times(2)
					var initialMaxPacketSize protocol.ByteCount
					framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).Do(func(_ []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						initialMaxPacketSize = maxLen
						return nil, 0
					})
					expectAppendStreamFrames()
					_, err := packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
					// now try to increase the maxPacketSize
					packer.HandleTransportParameters(&handshake.TransportParameters{
						MaxPacketSize: maxPacketSize + 10,
					})
					framer.EXPECT().AppendControlFrames(gomock.Any(), gomock.Any()).Do(func(_ []ackhandler.Frame, maxLen protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) {
						Expect(maxLen).To(Equal(initialMaxPacketSize))
						return nil, 0
					})
					expectAppendStreamFrames()
					_, err = packer.PackPacket()
					Expect(err).ToNot(HaveOccurred())
				})
			})
		})

		Context("packing crypto packets", func() {
			It("sets the length", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				f := &wire.CryptoFrame{
					Offset: 0x1337,
					Data:   []byte("foobar"),
				}
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				initialStream.EXPECT().HasData().Return(true)
				initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				checkLength(p.raw)
			})

			It("packs a maximum size crypto packet", func() {
				var f *wire.CryptoFrame
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetInitialSealer().Return(nil, errors.New("no sealer"))
				sealingManager.EXPECT().GetHandshakeSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake)
				initialStream.EXPECT().HasData()
				handshakeStream.EXPECT().HasData().Return(true)
				handshakeStream.EXPECT().PopCryptoFrame(gomock.Any()).DoAndReturn(func(size protocol.ByteCount) *wire.CryptoFrame {
					f = &wire.CryptoFrame{Offset: 0x1337}
					f.Data = bytes.Repeat([]byte{'f'}, int(size-f.Length(packer.version)-1))
					Expect(f.Length(packer.version)).To(Equal(size))
					return f
				})
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p.frames).To(HaveLen(1))
				Expect(p.raw).To(HaveLen(int(packer.maxPacketSize)))
				Expect(p.header.IsLongHeader).To(BeTrue())
				checkLength(p.raw)
			})

			It("adds retransmissions", func() {
				f := &wire.CryptoFrame{Data: []byte("Initial")}
				retransmissionQueue.AddInitial(f)
				retransmissionQueue.AddHandshake(&wire.CryptoFrame{Data: []byte("Handshake")})
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				initialStream.EXPECT().HasData()
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p.EncryptionLevel()).To(Equal(protocol.EncryptionInitial))
				Expect(p.frames).To(Equal([]ackhandler.Frame{{Frame: f}}))
				Expect(p.header.IsLongHeader).To(BeTrue())
				checkLength(p.raw)
			})

			It("sends an Initial packet containing only an ACK", func() {
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 10, Largest: 20}}}
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial).Return(ack)
				initialStream.EXPECT().HasData()
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p.ack).To(Equal(ack))
			})

			It("sends a Handshake packet containing only an ACK", func() {
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 10, Largest: 20}}}
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake).Return(ack)
				initialStream.EXPECT().HasData()
				handshakeStream.EXPECT().HasData()
				sealingManager.EXPECT().GetInitialSealer().Return(nil, errors.New("no sealer"))
				sealingManager.EXPECT().GetHandshakeSealer().Return(sealer, nil)
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionHandshake).Return(protocol.PacketNumber(0x42))
				p, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(p.ack).To(Equal(ack))
			})

			It("pads Initial packets to the required minimum packet size", func() {
				token := []byte("initial token")
				packer.SetToken(token)
				f := &wire.CryptoFrame{Data: []byte("foobar")}
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				initialStream.EXPECT().HasData().Return(true)
				initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
				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(1))
				cf := packet.frames[0].Frame.(*wire.CryptoFrame)
				Expect(cf.Data).To(Equal([]byte("foobar")))
			})

			It("sets the correct length for an Initial packet", func() {
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				initialStream.EXPECT().HasData().Return(true)
				initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(&wire.CryptoFrame{
					Data: []byte("foobar"),
				})
				packer.perspective = protocol.PerspectiveClient
				packet, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				checkLength(packet.raw)
			})

			It("adds an ACK frame", func() {
				f := &wire.CryptoFrame{Data: []byte("foobar")}
				ack := &wire.AckFrame{AckRanges: []wire.AckRange{{Smallest: 42, Largest: 1337}}}
				pnManager.EXPECT().PeekPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.EncryptionInitial).Return(protocol.PacketNumber(0x42))
				sealingManager.EXPECT().GetInitialSealer().Return(sealer, nil)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, errors.New("no sealer"))
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial).Return(ack)
				initialStream.EXPECT().HasData().Return(true)
				initialStream.EXPECT().PopCryptoFrame(gomock.Any()).Return(f)
				packer.version = protocol.VersionTLS
				packer.perspective = protocol.PerspectiveClient
				packet, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(packet.raw).To(HaveLen(protocol.MinInitialPacketSize))
				Expect(packet.ack).To(Equal(ack))
				Expect(packet.frames).To(HaveLen(1))
			})

			It("stops packing crypto packets when the keys are dropped", func() {
				sealingManager.EXPECT().GetInitialSealer().Return(nil, handshake.ErrKeysDropped)
				sealingManager.EXPECT().GetHandshakeSealer().Return(nil, handshake.ErrKeysDropped)
				initialStream.EXPECT().HasData()
				handshakeStream.EXPECT().HasData()
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionInitial)
				ackFramer.EXPECT().GetAckFrame(protocol.EncryptionHandshake)
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x42))
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames(ackhandler.Frame{Frame: &wire.PingFrame{}})
				expectAppendStreamFrames()
				packet, err := packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(packet).ToNot(BeNil())

				// now the packer should have realized that the handshake is confirmed
				sealingManager.EXPECT().Get1RTTSealer().Return(sealer, nil)
				pnManager.EXPECT().PeekPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x43), protocol.PacketNumberLen2)
				pnManager.EXPECT().PopPacketNumber(protocol.Encryption1RTT).Return(protocol.PacketNumber(0x43))
				ackFramer.EXPECT().GetAckFrame(protocol.Encryption1RTT)
				expectAppendControlFrames(ackhandler.Frame{Frame: &wire.PingFrame{}})
				expectAppendStreamFrames()
				packet, err = packer.PackPacket()
				Expect(err).ToNot(HaveOccurred())
				Expect(packet).ToNot(BeNil())
			})
		})
	})
})

var _ = Describe("Converting to AckHandler packets", func() {
	It("convert a packet", func() {
		packet := &packedPacket{
			header: &wire.ExtendedHeader{Header: wire.Header{}},
			frames: []ackhandler.Frame{{Frame: &wire.MaxDataFrame{}}, {Frame: &wire.PingFrame{}}},
			ack:    &wire.AckFrame{AckRanges: []wire.AckRange{{Largest: 100, Smallest: 80}}},
			raw:    []byte("foobar"),
		}
		p := packet.ToAckHandlerPacket(nil)
		Expect(p.Length).To(Equal(protocol.ByteCount(6)))
		Expect(p.Frames).To(Equal(packet.frames))
		Expect(p.LargestAcked).To(Equal(protocol.PacketNumber(100)))
		Expect(p.SendTime).To(BeTemporally("~", time.Now(), 50*time.Millisecond))
	})

	It("sets the LargestAcked to invalid, if the packet doesn't have an ACK frame", func() {
		packet := &packedPacket{
			header: &wire.ExtendedHeader{Header: wire.Header{}},
			frames: []ackhandler.Frame{{Frame: &wire.MaxDataFrame{}}, {Frame: &wire.PingFrame{}}},
			raw:    []byte("foobar"),
		}
		p := packet.ToAckHandlerPacket(nil)
		Expect(p.LargestAcked).To(Equal(protocol.InvalidPacketNumber))
	})

	It("doesn't overwrite the OnLost callback, if it is set", func() {
		var pingLost bool
		packet := &packedPacket{
			header: &wire.ExtendedHeader{Header: wire.Header{Type: protocol.PacketTypeHandshake}},
			frames: []ackhandler.Frame{
				{Frame: &wire.MaxDataFrame{}},
				{Frame: &wire.PingFrame{}, OnLost: func(wire.Frame) { pingLost = true }},
			},
			raw: []byte("foobar"),
		}
		p := packet.ToAckHandlerPacket(newRetransmissionQueue(protocol.VersionTLS))
		Expect(p.Frames).To(HaveLen(2))
		Expect(p.Frames[0].OnLost).ToNot(BeNil())
		p.Frames[1].OnLost(nil)
		Expect(pingLost).To(BeTrue())
	})
})