package quic import ( "bytes" "errors" "fmt" "net" "time" "github.com/lucas-clemente/quic-go/internal/ackhandler" "github.com/lucas-clemente/quic-go/internal/handshake" "github.com/lucas-clemente/quic-go/internal/protocol" "github.com/lucas-clemente/quic-go/internal/qerr" "github.com/lucas-clemente/quic-go/internal/utils" "github.com/lucas-clemente/quic-go/internal/wire" ) type packer interface { PackCoalescedPacket() (*coalescedPacket, error) PackPacket() (*packedPacket, error) MaybePackProbePacket(protocol.EncryptionLevel) (*packedPacket, error) MaybePackAckPacket(handshakeConfirmed bool) (*packedPacket, error) PackConnectionClose(*qerr.QuicError) (*coalescedPacket, error) SetMaxPacketSize(protocol.ByteCount) PackMTUProbePacket(ping ackhandler.Frame, size protocol.ByteCount) (*packedPacket, error) HandleTransportParameters(*wire.TransportParameters) SetToken([]byte) } type sealer interface { handshake.LongHeaderSealer } type payload struct { frames []ackhandler.Frame ack *wire.AckFrame length protocol.ByteCount } type packedPacket struct { buffer *packetBuffer *packetContents } type packetContents struct { header *wire.ExtendedHeader ack *wire.AckFrame frames []ackhandler.Frame length protocol.ByteCount isMTUProbePacket bool } type coalescedPacket struct { buffer *packetBuffer packets []*packetContents } func (p *packetContents) EncryptionLevel() protocol.EncryptionLevel { if !p.header.IsLongHeader { return protocol.Encryption1RTT } //nolint:exhaustive // Will never be called for Retry packets (and they don't have encrypted data). switch p.header.Type { case protocol.PacketTypeInitial: return protocol.EncryptionInitial case protocol.PacketTypeHandshake: return protocol.EncryptionHandshake case protocol.PacketType0RTT: return protocol.Encryption0RTT default: panic("can't determine encryption level") } } func (p *packetContents) IsAckEliciting() bool { return ackhandler.HasAckElicitingFrames(p.frames) } func (p *packetContents) ToAckHandlerPacket(now time.Time, q *retransmissionQueue) *ackhandler.Packet { largestAcked := protocol.InvalidPacketNumber if p.ack != nil { largestAcked = p.ack.LargestAcked() } encLevel := p.EncryptionLevel() for i := range p.frames { if p.frames[i].OnLost != nil { continue } switch encLevel { case protocol.EncryptionInitial: p.frames[i].OnLost = q.AddInitial case protocol.EncryptionHandshake: p.frames[i].OnLost = q.AddHandshake case protocol.Encryption0RTT, protocol.Encryption1RTT: p.frames[i].OnLost = q.AddAppData } } return &ackhandler.Packet{ PacketNumber: p.header.PacketNumber, LargestAcked: largestAcked, Frames: p.frames, Length: p.length, EncryptionLevel: encLevel, SendTime: now, IsPathMTUProbePacket: p.isMTUProbePacket, } } func getMaxPacketSize(addr net.Addr) protocol.ByteCount { maxSize := protocol.ByteCount(protocol.MinInitialPacketSize) // If this is not a UDP address, we don't know anything about the MTU. // Use the minimum size of an Initial packet as the max packet size. if udpAddr, ok := addr.(*net.UDPAddr); ok { if utils.IsIPv4(udpAddr.IP) { maxSize = protocol.InitialPacketSizeIPv4 } else { maxSize = protocol.InitialPacketSizeIPv6 } } return maxSize } type packetNumberManager interface { PeekPacketNumber(protocol.EncryptionLevel) (protocol.PacketNumber, protocol.PacketNumberLen) PopPacketNumber(protocol.EncryptionLevel) protocol.PacketNumber } type sealingManager interface { GetInitialSealer() (handshake.LongHeaderSealer, error) GetHandshakeSealer() (handshake.LongHeaderSealer, error) Get0RTTSealer() (handshake.LongHeaderSealer, error) Get1RTTSealer() (handshake.ShortHeaderSealer, error) } type frameSource interface { HasData() bool AppendStreamFrames([]ackhandler.Frame, protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) AppendControlFrames([]ackhandler.Frame, protocol.ByteCount) ([]ackhandler.Frame, protocol.ByteCount) } type ackFrameSource interface { GetAckFrame(encLevel protocol.EncryptionLevel, onlyIfQueued bool) *wire.AckFrame } type packetPacker struct { srcConnID protocol.ConnectionID getDestConnID func() protocol.ConnectionID perspective protocol.Perspective version protocol.VersionNumber cryptoSetup sealingManager initialStream cryptoStream handshakeStream cryptoStream token []byte pnManager packetNumberManager framer frameSource acks ackFrameSource datagramQueue *datagramQueue retransmissionQueue *retransmissionQueue maxPacketSize protocol.ByteCount numNonAckElicitingAcks int } var _ packer = &packetPacker{} func newPacketPacker( srcConnID protocol.ConnectionID, getDestConnID func() protocol.ConnectionID, initialStream cryptoStream, handshakeStream cryptoStream, packetNumberManager packetNumberManager, retransmissionQueue *retransmissionQueue, remoteAddr net.Addr, // only used for determining the max packet size cryptoSetup sealingManager, framer frameSource, acks ackFrameSource, datagramQueue *datagramQueue, perspective protocol.Perspective, version protocol.VersionNumber, ) *packetPacker { return &packetPacker{ cryptoSetup: cryptoSetup, getDestConnID: getDestConnID, srcConnID: srcConnID, initialStream: initialStream, handshakeStream: handshakeStream, retransmissionQueue: retransmissionQueue, datagramQueue: datagramQueue, perspective: perspective, version: version, framer: framer, acks: acks, pnManager: packetNumberManager, maxPacketSize: getMaxPacketSize(remoteAddr), } } // PackConnectionClose packs a packet that ONLY contains a ConnectionCloseFrame func (p *packetPacker) PackConnectionClose(quicErr *qerr.QuicError) (*coalescedPacket, error) { var reason string // don't send details of crypto errors if !quicErr.IsCryptoError() { reason = quicErr.ErrorMessage } var sealers [4]sealer var hdrs [4]*wire.ExtendedHeader var payloads [4]*payload var size protocol.ByteCount var numPackets uint8 encLevels := [4]protocol.EncryptionLevel{protocol.EncryptionInitial, protocol.EncryptionHandshake, protocol.Encryption0RTT, protocol.Encryption1RTT} for i, encLevel := range encLevels { if p.perspective == protocol.PerspectiveServer && encLevel == protocol.Encryption0RTT { continue } quicErrToSend := quicErr reasonPhrase := reason if encLevel == protocol.EncryptionInitial || encLevel == protocol.EncryptionHandshake { // don't send application errors in Initial or Handshake packets if quicErr.IsApplicationError() { quicErrToSend = qerr.NewError(qerr.ApplicationError, "") reasonPhrase = "" } } ccf := &wire.ConnectionCloseFrame{ IsApplicationError: quicErrToSend.IsApplicationError(), ErrorCode: quicErrToSend.ErrorCode, FrameType: quicErrToSend.FrameType, ReasonPhrase: reasonPhrase, } payload := &payload{ frames: []ackhandler.Frame{{Frame: ccf}}, length: ccf.Length(p.version), } var sealer sealer var err error var keyPhase protocol.KeyPhaseBit // only set for 1-RTT switch encLevel { case protocol.EncryptionInitial: sealer, err = p.cryptoSetup.GetInitialSealer() case protocol.EncryptionHandshake: sealer, err = p.cryptoSetup.GetHandshakeSealer() case protocol.Encryption0RTT: sealer, err = p.cryptoSetup.Get0RTTSealer() case protocol.Encryption1RTT: var s handshake.ShortHeaderSealer s, err = p.cryptoSetup.Get1RTTSealer() if err == nil { keyPhase = s.KeyPhase() } sealer = s } if err == handshake.ErrKeysNotYetAvailable || err == handshake.ErrKeysDropped { continue } if err != nil { return nil, err } sealers[i] = sealer var hdr *wire.ExtendedHeader if encLevel == protocol.Encryption1RTT { hdr = p.getShortHeader(keyPhase) } else { hdr = p.getLongHeader(encLevel) } hdrs[i] = hdr payloads[i] = payload size += p.packetLength(hdr, payload) + protocol.ByteCount(sealer.Overhead()) numPackets++ } contents := make([]*packetContents, 0, numPackets) buffer := getPacketBuffer() for i, encLevel := range encLevels { if sealers[i] == nil { continue } var paddingLen protocol.ByteCount if encLevel == protocol.EncryptionInitial { paddingLen = p.initialPaddingLen(payloads[i].frames, size) } c, err := p.appendPacket(buffer, hdrs[i], payloads[i], paddingLen, encLevel, sealers[i], false) if err != nil { return nil, err } contents = append(contents, c) } return &coalescedPacket{buffer: buffer, packets: contents}, nil } // packetLength calculates the length of the serialized packet. // It takes into account that packets that have a tiny payload need to be padded, // such that len(payload) + packet number len >= 4 + AEAD overhead func (p *packetPacker) packetLength(hdr *wire.ExtendedHeader, payload *payload) protocol.ByteCount { var paddingLen protocol.ByteCount pnLen := protocol.ByteCount(hdr.PacketNumberLen) if payload.length < 4-pnLen { paddingLen = 4 - pnLen - payload.length } return hdr.GetLength(p.version) + payload.length + paddingLen } func (p *packetPacker) MaybePackAckPacket(handshakeConfirmed bool) (*packedPacket, error) { var encLevel protocol.EncryptionLevel var ack *wire.AckFrame if !handshakeConfirmed { ack = p.acks.GetAckFrame(protocol.EncryptionInitial, true) if ack != nil { encLevel = protocol.EncryptionInitial } else { ack = p.acks.GetAckFrame(protocol.EncryptionHandshake, true) if ack != nil { encLevel = protocol.EncryptionHandshake } } } if ack == nil { ack = p.acks.GetAckFrame(protocol.Encryption1RTT, true) if ack == nil { return nil, nil } encLevel = protocol.Encryption1RTT } payload := &payload{ ack: ack, length: ack.Length(p.version), } sealer, hdr, err := p.getSealerAndHeader(encLevel) if err != nil { return nil, err } return p.writeSinglePacket(hdr, payload, encLevel, sealer) } // size is the expected size of the packet, if no padding was applied. func (p *packetPacker) initialPaddingLen(frames []ackhandler.Frame, size protocol.ByteCount) protocol.ByteCount { // For the server, only ack-eliciting Initial packets need to be padded. if p.perspective == protocol.PerspectiveServer && !ackhandler.HasAckElicitingFrames(frames) { return 0 } if size >= p.maxPacketSize { return 0 } return p.maxPacketSize - size } // PackCoalescedPacket packs a new packet. // It packs an Initial / Handshake if there is data to send in these packet number spaces. // It should only be called before the handshake is confirmed. func (p *packetPacker) PackCoalescedPacket() (*coalescedPacket, error) { maxPacketSize := p.maxPacketSize if p.perspective == protocol.PerspectiveClient { maxPacketSize = protocol.MinInitialPacketSize } var initialHdr, handshakeHdr, appDataHdr *wire.ExtendedHeader var initialPayload, handshakePayload, appDataPayload *payload var numPackets int // Try packing an Initial packet. initialSealer, err := p.cryptoSetup.GetInitialSealer() if err != nil && err != handshake.ErrKeysDropped { return nil, err } var size protocol.ByteCount if initialSealer != nil { initialHdr, initialPayload = p.maybeGetCryptoPacket(maxPacketSize-protocol.ByteCount(initialSealer.Overhead()), size, protocol.EncryptionInitial) if initialPayload != nil { size += p.packetLength(initialHdr, initialPayload) + protocol.ByteCount(initialSealer.Overhead()) numPackets++ } } // Add a Handshake packet. var handshakeSealer sealer if size < maxPacketSize-protocol.MinCoalescedPacketSize { var err error handshakeSealer, err = p.cryptoSetup.GetHandshakeSealer() if err != nil && err != handshake.ErrKeysDropped && err != handshake.ErrKeysNotYetAvailable { return nil, err } if handshakeSealer != nil { handshakeHdr, handshakePayload = p.maybeGetCryptoPacket(maxPacketSize-size-protocol.ByteCount(handshakeSealer.Overhead()), size, protocol.EncryptionHandshake) if handshakePayload != nil { s := p.packetLength(handshakeHdr, handshakePayload) + protocol.ByteCount(handshakeSealer.Overhead()) size += s numPackets++ } } } // Add a 0-RTT / 1-RTT packet. var appDataSealer sealer appDataEncLevel := protocol.Encryption1RTT if size < maxPacketSize-protocol.MinCoalescedPacketSize { var err error appDataSealer, appDataHdr, appDataPayload = p.maybeGetAppDataPacket(maxPacketSize-size, size) if err != nil { return nil, err } if appDataHdr != nil { if appDataHdr.IsLongHeader { appDataEncLevel = protocol.Encryption0RTT } if appDataPayload != nil { size += p.packetLength(appDataHdr, appDataPayload) + protocol.ByteCount(appDataSealer.Overhead()) numPackets++ } } } if numPackets == 0 { return nil, nil } buffer := getPacketBuffer() packet := &coalescedPacket{ buffer: buffer, packets: make([]*packetContents, 0, numPackets), } if initialPayload != nil { padding := p.initialPaddingLen(initialPayload.frames, size) cont, err := p.appendPacket(buffer, initialHdr, initialPayload, padding, protocol.EncryptionInitial, initialSealer, false) if err != nil { return nil, err } packet.packets = append(packet.packets, cont) } if handshakePayload != nil { cont, err := p.appendPacket(buffer, handshakeHdr, handshakePayload, 0, protocol.EncryptionHandshake, handshakeSealer, false) if err != nil { return nil, err } packet.packets = append(packet.packets, cont) } if appDataPayload != nil { cont, err := p.appendPacket(buffer, appDataHdr, appDataPayload, 0, appDataEncLevel, appDataSealer, false) if err != nil { return nil, err } packet.packets = append(packet.packets, cont) } return packet, nil } // PackPacket packs a packet in the application data packet number space. // It should be called after the handshake is confirmed. func (p *packetPacker) PackPacket() (*packedPacket, error) { sealer, hdr, payload := p.maybeGetAppDataPacket(p.maxPacketSize, 0) if payload == nil { return nil, nil } buffer := getPacketBuffer() encLevel := protocol.Encryption1RTT if hdr.IsLongHeader { encLevel = protocol.Encryption0RTT } cont, err := p.appendPacket(buffer, hdr, payload, 0, encLevel, sealer, false) if err != nil { return nil, err } return &packedPacket{ buffer: buffer, packetContents: cont, }, nil } 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. switch encLevel { case protocol.EncryptionInitial: s = p.initialStream hasRetransmission = p.retransmissionQueue.HasInitialData() case protocol.EncryptionHandshake: s = p.handshakeStream hasRetransmission = p.retransmissionQueue.HasHandshakeData() } hasData := s.HasData() var ack *wire.AckFrame if encLevel == protocol.EncryptionInitial || currentSize == 0 { ack = p.acks.GetAckFrame(encLevel, !hasRetransmission && !hasData) } if !hasData && !hasRetransmission && ack == nil { // nothing to send return nil, nil } var payload payload if ack != nil { payload.ack = ack payload.length = ack.Length(p.version) maxPacketSize -= payload.length } hdr := p.getLongHeader(encLevel) 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(maxPacketSize) case protocol.EncryptionHandshake: 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 maxPacketSize -= frameLen } } else if s.HasData() { cf := s.PopCryptoFrame(maxPacketSize) payload.frames = []ackhandler.Frame{{Frame: cf}} payload.length += cf.Length(p.version) } return hdr, &payload } func (p *packetPacker) maybeGetAppDataPacket(maxPacketSize, currentSize protocol.ByteCount) (sealer, *wire.ExtendedHeader, *payload) { var sealer sealer var encLevel protocol.EncryptionLevel var hdr *wire.ExtendedHeader oneRTTSealer, err := p.cryptoSetup.Get1RTTSealer() if err == nil { encLevel = protocol.Encryption1RTT sealer = oneRTTSealer hdr = p.getShortHeader(oneRTTSealer.KeyPhase()) } else { // 1-RTT sealer not yet available if p.perspective != protocol.PerspectiveClient { return nil, nil, nil } sealer, err = p.cryptoSetup.Get0RTTSealer() if sealer == nil || err != nil { return nil, nil, nil } encLevel = protocol.Encryption0RTT hdr = p.getLongHeader(protocol.Encryption0RTT) } maxPayloadSize := maxPacketSize - hdr.GetLength(p.version) - protocol.ByteCount(sealer.Overhead()) payload := p.maybeGetAppDataPacketWithEncLevel(maxPayloadSize, encLevel == protocol.Encryption1RTT && currentSize == 0) return sealer, hdr, payload } 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 { if payload.ack == nil { return nil } // the packet only contains an ACK if p.numNonAckElicitingAcks >= protocol.MaxNonAckElicitingAcks { ping := &wire.PingFrame{} // don't retransmit the PING frame when it is lost payload.frames = append(payload.frames, ackhandler.Frame{Frame: ping, OnLost: func(wire.Frame) {}}) payload.length += ping.Length(p.version) p.numNonAckElicitingAcks = 0 } else { p.numNonAckElicitingAcks++ } } else { p.numNonAckElicitingAcks = 0 } return payload } func (p *packetPacker) composeNextPacket(maxFrameSize protocol.ByteCount, ackAllowed bool) *payload { payload := &payload{frames: make([]ackhandler.Frame, 0, 1)} var hasDatagram bool if p.datagramQueue != nil { if datagram := p.datagramQueue.Get(); datagram != nil { payload.frames = append(payload.frames, ackhandler.Frame{ Frame: datagram, // set it to a no-op. Then we won't set the default callback, which would retransmit the frame. OnLost: func(wire.Frame) {}, }) payload.length += datagram.Length(p.version) hasDatagram = true } } var ack *wire.AckFrame hasData := p.framer.HasData() hasRetransmission := p.retransmissionQueue.HasAppData() // TODO: make sure ACKs are sent when a lot of DATAGRAMs are queued if !hasDatagram && ackAllowed { ack = p.acks.GetAckFrame(protocol.Encryption1RTT, !hasRetransmission && !hasData) if ack != nil { payload.ack = ack payload.length += ack.Length(p.version) } } if ack == nil && !hasData && !hasRetransmission { return payload } if hasRetransmission { for { remainingLen := maxFrameSize - payload.length if remainingLen < protocol.MinStreamFrameSize { break } f := p.retransmissionQueue.GetAppDataFrame(remainingLen) if f == nil { break } payload.frames = append(payload.frames, ackhandler.Frame{Frame: f}) payload.length += f.Length(p.version) } } if hasData { var lengthAdded protocol.ByteCount payload.frames, lengthAdded = p.framer.AppendControlFrames(payload.frames, maxFrameSize-payload.length) payload.length += lengthAdded payload.frames, lengthAdded = p.framer.AppendStreamFrames(payload.frames, maxFrameSize-payload.length) payload.length += lengthAdded } return payload } func (p *packetPacker) MaybePackProbePacket(encLevel protocol.EncryptionLevel) (*packedPacket, error) { var hdr *wire.ExtendedHeader var payload *payload var sealer sealer //nolint:exhaustive // Probe packets are never sent for 0-RTT. switch encLevel { case protocol.EncryptionInitial: var err error sealer, err = p.cryptoSetup.GetInitialSealer() if err != nil { return nil, err } hdr, payload = p.maybeGetCryptoPacket(p.maxPacketSize-protocol.ByteCount(sealer.Overhead()), 0, protocol.EncryptionInitial) case protocol.EncryptionHandshake: var err error sealer, err = p.cryptoSetup.GetHandshakeSealer() if err != nil { return nil, err } hdr, payload = p.maybeGetCryptoPacket(p.maxPacketSize-protocol.ByteCount(sealer.Overhead()), 0, protocol.EncryptionHandshake) case protocol.Encryption1RTT: oneRTTSealer, err := p.cryptoSetup.Get1RTTSealer() if err != nil { return nil, err } sealer = oneRTTSealer 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 payload == nil { return nil, nil } size := p.packetLength(hdr, payload) + protocol.ByteCount(sealer.Overhead()) var padding protocol.ByteCount if encLevel == protocol.EncryptionInitial { padding = p.initialPaddingLen(payload.frames, size) } buffer := getPacketBuffer() cont, err := p.appendPacket(buffer, hdr, payload, padding, encLevel, sealer, false) if err != nil { return nil, err } return &packedPacket{ buffer: buffer, packetContents: cont, }, nil } func (p *packetPacker) PackMTUProbePacket(ping ackhandler.Frame, size protocol.ByteCount) (*packedPacket, error) { payload := &payload{ frames: []ackhandler.Frame{ping}, length: ping.Length(p.version), } buffer := getPacketBuffer() sealer, err := p.cryptoSetup.Get1RTTSealer() if err != nil { return nil, err } hdr := p.getShortHeader(sealer.KeyPhase()) padding := size - p.packetLength(hdr, payload) - protocol.ByteCount(sealer.Overhead()) contents, err := p.appendPacket(buffer, hdr, payload, padding, protocol.Encryption1RTT, sealer, true) if err != nil { return nil, err } contents.isMTUProbePacket = true return &packedPacket{ buffer: buffer, packetContents: contents, }, nil } func (p *packetPacker) getSealerAndHeader(encLevel protocol.EncryptionLevel) (sealer, *wire.ExtendedHeader, error) { switch encLevel { case protocol.EncryptionInitial: sealer, err := p.cryptoSetup.GetInitialSealer() if err != nil { return nil, nil, err } hdr := p.getLongHeader(protocol.EncryptionInitial) return sealer, hdr, nil case protocol.Encryption0RTT: sealer, err := p.cryptoSetup.Get0RTTSealer() if err != nil { return nil, nil, err } hdr := p.getLongHeader(protocol.Encryption0RTT) return sealer, hdr, nil case protocol.EncryptionHandshake: sealer, err := p.cryptoSetup.GetHandshakeSealer() if err != nil { return nil, nil, err } hdr := p.getLongHeader(protocol.EncryptionHandshake) return sealer, hdr, nil case protocol.Encryption1RTT: sealer, err := p.cryptoSetup.Get1RTTSealer() if err != nil { return nil, nil, err } hdr := p.getShortHeader(sealer.KeyPhase()) return sealer, hdr, nil default: return nil, nil, fmt.Errorf("unexpected encryption level: %s", encLevel) } } func (p *packetPacker) getShortHeader(kp protocol.KeyPhaseBit) *wire.ExtendedHeader { pn, pnLen := p.pnManager.PeekPacketNumber(protocol.Encryption1RTT) hdr := &wire.ExtendedHeader{} hdr.PacketNumber = pn hdr.PacketNumberLen = pnLen hdr.DestConnectionID = p.getDestConnID() hdr.KeyPhase = kp return hdr } func (p *packetPacker) getLongHeader(encLevel protocol.EncryptionLevel) *wire.ExtendedHeader { pn, pnLen := p.pnManager.PeekPacketNumber(encLevel) hdr := &wire.ExtendedHeader{ PacketNumber: pn, PacketNumberLen: pnLen, } hdr.IsLongHeader = true hdr.Version = p.version hdr.SrcConnectionID = p.srcConnID hdr.DestConnectionID = p.getDestConnID() //nolint:exhaustive // 1-RTT packets are not long header packets. switch encLevel { case protocol.EncryptionInitial: hdr.Type = protocol.PacketTypeInitial hdr.Token = p.token case protocol.EncryptionHandshake: hdr.Type = protocol.PacketTypeHandshake case protocol.Encryption0RTT: hdr.Type = protocol.PacketType0RTT } return hdr } // writeSinglePacket packs a single packet. func (p *packetPacker) writeSinglePacket( hdr *wire.ExtendedHeader, payload *payload, encLevel protocol.EncryptionLevel, sealer sealer, ) (*packedPacket, error) { buffer := getPacketBuffer() var paddingLen protocol.ByteCount if encLevel == protocol.EncryptionInitial { paddingLen = p.initialPaddingLen(payload.frames, hdr.GetLength(p.version)+payload.length+protocol.ByteCount(sealer.Overhead())) } contents, err := p.appendPacket(buffer, hdr, payload, paddingLen, encLevel, sealer, false) if err != nil { return nil, err } return &packedPacket{ buffer: buffer, packetContents: contents, }, nil } func (p *packetPacker) appendPacket(buffer *packetBuffer, header *wire.ExtendedHeader, payload *payload, padding protocol.ByteCount, encLevel protocol.EncryptionLevel, sealer sealer, isMTUProbePacket bool) (*packetContents, error) { var paddingLen protocol.ByteCount pnLen := protocol.ByteCount(header.PacketNumberLen) if payload.length < 4-pnLen { paddingLen = 4 - pnLen - payload.length } paddingLen += padding if header.IsLongHeader { header.Length = pnLen + protocol.ByteCount(sealer.Overhead()) + payload.length + paddingLen } hdrOffset := buffer.Len() buf := bytes.NewBuffer(buffer.Data) if err := header.Write(buf, p.version); err != nil { return nil, err } payloadOffset := buf.Len() if payload.ack != nil { if err := payload.ack.Write(buf, p.version); err != nil { return nil, err } } if paddingLen > 0 { buf.Write(make([]byte, paddingLen)) } for _, frame := range payload.frames { if err := frame.Write(buf, p.version); err != nil { return nil, err } } if payloadSize := protocol.ByteCount(buf.Len()-payloadOffset) - paddingLen; payloadSize != payload.length { return nil, fmt.Errorf("PacketPacker BUG: payload size inconsistent (expected %d, got %d bytes)", payload.length, payloadSize) } if !isMTUProbePacket { if size := protocol.ByteCount(buf.Len() + sealer.Overhead()); size > p.maxPacketSize { return nil, fmt.Errorf("PacketPacker BUG: packet too large (%d bytes, allowed %d bytes)", size, p.maxPacketSize) } } raw := buffer.Data // encrypt the packet raw = raw[:buf.Len()] _ = sealer.Seal(raw[payloadOffset:payloadOffset], raw[payloadOffset:], header.PacketNumber, raw[hdrOffset:payloadOffset]) raw = raw[0 : buf.Len()+sealer.Overhead()] // apply header protection pnOffset := payloadOffset - int(header.PacketNumberLen) sealer.EncryptHeader(raw[pnOffset+4:pnOffset+4+16], &raw[hdrOffset], raw[pnOffset:payloadOffset]) buffer.Data = raw num := p.pnManager.PopPacketNumber(encLevel) if num != header.PacketNumber { return nil, errors.New("packetPacker BUG: Peeked and Popped packet numbers do not match") } return &packetContents{ header: header, ack: payload.ack, frames: payload.frames, length: buffer.Len() - hdrOffset, }, nil } func (p *packetPacker) SetToken(token []byte) { p.token = token } // When a higher MTU is discovered, use it. func (p *packetPacker) SetMaxPacketSize(s protocol.ByteCount) { p.maxPacketSize = s } // If the peer sets a max_packet_size that's smaller than the size we're currently using, // we need to reduce the size of packets we send. func (p *packetPacker) HandleTransportParameters(params *wire.TransportParameters) { if params.MaxUDPPayloadSize != 0 { p.maxPacketSize = utils.MinByteCount(p.maxPacketSize, params.MaxUDPPayloadSize) } }