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split the packet packer into two structs, for gQUIC and for IETF QUIC
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@marten-seemann
marten-seemann committed Oct 9, 2018
1 parent 225106b commit 5df98dc
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Showing 5 changed files with 1,436 additions and 431 deletions.
105 changes: 14 additions & 91 deletions packet_packer.go
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Expand Up @@ -70,14 +70,6 @@ type frameSource interface {
AppendControlFrames([]wire.Frame, protocol.ByteCount) ([]wire.Frame, protocol.ByteCount)
}

// sentAndReceivedPacketManager is only needed until STOP_WAITING is removed
type sentAndReceivedPacketManager struct {
ackhandler.SentPacketHandler
ackhandler.ReceivedPacketHandler
}

var _ ackFrameSource = &sentAndReceivedPacketManager{}

type ackFrameSource interface {
GetAckFrame() *wire.AckFrame
GetStopWaitingFrame(bool) *wire.StopWaitingFrame
Expand All @@ -91,16 +83,14 @@ type packetPacker struct {
version protocol.VersionNumber
cryptoSetup sealingManager

token []byte
divNonce []byte
token []byte

packetNumberGenerator *packetNumberGenerator
getPacketNumberLen func(protocol.PacketNumber) protocol.PacketNumberLen
cryptoStream cryptoStream
framer frameSource
acks ackFrameSource

omitConnectionID bool
maxPacketSize protocol.ByteCount
hasSentPacket bool // has the packetPacker already sent a packet
numNonRetransmittableAcks int
Expand All @@ -115,7 +105,6 @@ func newPacketPacker(
getPacketNumberLen func(protocol.PacketNumber) protocol.PacketNumberLen,
remoteAddr net.Addr, // only used for determining the max packet size
token []byte,
divNonce []byte,
cryptoStream cryptoStream,
cryptoSetup sealingManager,
framer frameSource,
Expand All @@ -126,7 +115,6 @@ func newPacketPacker(
return &packetPacker{
cryptoStream: cryptoStream,
cryptoSetup: cryptoSetup,
divNonce: divNonce,
token: token,
destConnID: destConnID,
srcConnID: srcConnID,
Expand Down Expand Up @@ -162,14 +150,6 @@ func (p *packetPacker) MaybePackAckPacket() (*packedPacket, error) {
encLevel, sealer := p.cryptoSetup.GetSealer()
header := p.getHeader(encLevel)
frames := []wire.Frame{ack}
// add a STOP_WAITING frame, when using gQUIC
if p.version.UsesStopWaitingFrames() {
if swf := p.acks.GetStopWaitingFrame(false); swf != nil {
swf.PacketNumber = header.PacketNumber
swf.PacketNumberLen = header.PacketNumberLen
frames = append(frames, swf)
}
}
raw, err := p.writeAndSealPacket(header, frames, sealer)
return &packedPacket{
header: header,
Expand Down Expand Up @@ -201,11 +181,6 @@ func (p *packetPacker) PackRetransmission(packet *ackhandler.Packet) ([]*packedP

var packets []*packedPacket
encLevel, sealer := p.cryptoSetup.GetSealer()
var swf *wire.StopWaitingFrame
// for gQUIC: add a STOP_WAITING for *every* retransmission
if p.version.UsesStopWaitingFrames() {
swf = p.acks.GetStopWaitingFrame(true)
}
for len(controlFrames) > 0 || len(streamFrames) > 0 {
var frames []wire.Frame
var length protocol.ByteCount
Expand All @@ -217,17 +192,6 @@ func (p *packetPacker) PackRetransmission(packet *ackhandler.Packet) ([]*packedP
}
maxSize := p.maxPacketSize - protocol.ByteCount(sealer.Overhead()) - headerLength

if p.version.UsesStopWaitingFrames() {
// create a new STOP_WAIITNG Frame, since we might need to send more than one packet as a retransmission
stopWaitingFrame := &wire.StopWaitingFrame{
LeastUnacked: swf.LeastUnacked,
PacketNumber: header.PacketNumber,
PacketNumberLen: header.PacketNumberLen,
}
length += stopWaitingFrame.Length(p.version)
frames = append(frames, stopWaitingFrame)
}

for len(controlFrames) > 0 {
frame := controlFrames[0]
frameLen := frame.Length(p.version)
Expand Down Expand Up @@ -286,20 +250,11 @@ func (p *packetPacker) packHandshakeRetransmission(packet *ackhandler.Packet) (*
}
header := p.getHeader(packet.EncryptionLevel)
header.Type = packet.PacketType
var frames []wire.Frame
if p.version.UsesStopWaitingFrames() { // for gQUIC: pack a STOP_WAITING first
swf := p.acks.GetStopWaitingFrame(true)
swf.PacketNumber = header.PacketNumber
swf.PacketNumberLen = header.PacketNumberLen
frames = append([]wire.Frame{swf}, packet.Frames...)
} else {
frames = packet.Frames
}
raw, err := p.writeAndSealPacket(header, frames, sealer)
raw, err := p.writeAndSealPacket(header, packet.Frames, sealer)
return &packedPacket{
header: header,
raw: raw,
frames: frames,
frames: packet.Frames,
encryptionLevel: packet.EncryptionLevel,
}, err
}
Expand Down Expand Up @@ -328,7 +283,7 @@ func (p *packetPacker) PackPacket() (*packedPacket, error) {
}

maxSize := p.maxPacketSize - protocol.ByteCount(sealer.Overhead()) - headerLength
frames, err := p.composeNextPacket(header, maxSize, p.canSendData(encLevel))
frames, err := p.composeNextPacket(maxSize, p.canSendData(encLevel))
if err != nil {
return nil, err
}
Expand All @@ -337,7 +292,7 @@ func (p *packetPacker) PackPacket() (*packedPacket, error) {
if len(frames) == 0 {
return nil, nil
}
// check if this packet only contains an ACK (and maybe a STOP_WAITING)
// check if this packet only contains an ACK
if !ackhandler.HasRetransmittableFrames(frames) {
if p.numNonRetransmittableAcks >= protocol.MaxNonRetransmittableAcks {
frames = append(frames, &wire.PingFrame{})
Expand Down Expand Up @@ -388,27 +343,16 @@ func (p *packetPacker) maybePackCryptoPacket() (*packedPacket, error) {
}

func (p *packetPacker) composeNextPacket(
header *wire.Header, // only needed to fill in the STOP_WAITING frame
maxFrameSize protocol.ByteCount,
canSendStreamFrames bool,
) ([]wire.Frame, error) {
var length protocol.ByteCount
var frames []wire.Frame

// STOP_WAITING and ACK will always fit
// ACKs need to go first, so that the sentPacketHandler will recognize them
if ack := p.acks.GetAckFrame(); ack != nil {
frames = append(frames, ack)
length += ack.Length(p.version)
// add a STOP_WAITING, for gQUIC
if p.version.UsesStopWaitingFrames() {
if swf := p.acks.GetStopWaitingFrame(false); swf != nil {
swf.PacketNumber = header.PacketNumber
swf.PacketNumberLen = header.PacketNumberLen
frames = append(frames, swf)
length += swf.Length(p.version)
}
}
}

var lengthAdded protocol.ByteCount
Expand All @@ -420,15 +364,10 @@ func (p *packetPacker) composeNextPacket(
}

// temporarily increase the maxFrameSize by the (minimum) length of the DataLen field
// this leads to a properly sized packet in all cases, since we do all the packet length calculations with StreamFrames that have the DataLen set
// this leads to a properly sized packet in all cases, since we do all the packet length calculations with STREAM frames that have the DataLen set
// however, for the last STREAM frame in the packet, we can omit the DataLen, thus yielding a packet of exactly the correct size
// for gQUIC STREAM frames, DataLen is always 2 bytes
// for IETF draft style STREAM frames, the length is encoded to either 1 or 2 bytes
if p.version.UsesIETFFrameFormat() {
maxFrameSize++
} else {
maxFrameSize += 2
}
// the length is encoded to either 1 or 2 bytes
maxFrameSize++

frames = p.framer.AppendStreamFrames(frames, maxFrameSize-length)
if len(frames) > 0 {
Expand All @@ -445,17 +384,15 @@ func (p *packetPacker) getHeader(encLevel protocol.EncryptionLevel) *wire.Header
packetNumberLen := p.getPacketNumberLen(pnum)

header := &wire.Header{
PacketNumber: pnum,
PacketNumberLen: packetNumberLen,
Version: p.version,
PacketNumber: pnum,
PacketNumberLen: packetNumberLen,
Version: p.version,
DestConnectionID: p.destConnID,
}

if p.version.UsesIETFHeaderFormat() && encLevel != protocol.EncryptionForwardSecure {
if encLevel != protocol.EncryptionForwardSecure {
header.IsLongHeader = true
header.SrcConnectionID = p.srcConnID
if !p.version.UsesVarintPacketNumbers() {
header.PacketNumberLen = protocol.PacketNumberLen4
}
// Set the payload len to maximum size.
// Since it is encoded as a varint, this guarantees us that the header will end up at most as big as GetLength() returns.
header.PayloadLen = p.maxPacketSize
Expand All @@ -467,18 +404,6 @@ func (p *packetPacker) getHeader(encLevel protocol.EncryptionLevel) *wire.Header
}
}

if !p.omitConnectionID || encLevel != protocol.EncryptionForwardSecure {
header.DestConnectionID = p.destConnID
}
if !p.version.UsesTLS() {
if p.perspective == protocol.PerspectiveServer && encLevel == protocol.EncryptionSecure {
header.Type = protocol.PacketType0RTT
header.DiversificationNonce = p.divNonce
}
if p.perspective == protocol.PerspectiveClient && encLevel != protocol.EncryptionForwardSecure {
header.VersionFlag = true
}
}
return header
}

Expand Down Expand Up @@ -521,8 +446,7 @@ func (p *packetPacker) writeAndSealPacket(
return nil, err
}
}
// if this is an IETF QUIC Initial packet, we need to pad it to fulfill the minimum size requirement
// in gQUIC, padding is handled in the CHLO
// if this is an Initial packet, we need to pad it to fulfill the minimum size requirement
if header.Type == protocol.PacketTypeInitial {
paddingLen := protocol.MinInitialPacketSize - sealer.Overhead() - buffer.Len()
if paddingLen > 0 {
Expand Down Expand Up @@ -558,7 +482,6 @@ func (p *packetPacker) ChangeDestConnectionID(connID protocol.ConnectionID) {
}

func (p *packetPacker) HandleTransportParameters(params *handshake.TransportParameters) {
p.omitConnectionID = params.OmitConnectionID
if params.MaxPacketSize != 0 {
p.maxPacketSize = utils.MinByteCount(p.maxPacketSize, params.MaxPacketSize)
}
Expand Down

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