cloudflared-mirror/quic/datagramv2.go

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package quic
import (
"context"
"fmt"
"github.com/lucas-clemente/quic-go"
"github.com/pkg/errors"
"github.com/rs/zerolog"
"github.com/cloudflare/cloudflared/packet"
)
type DatagramV2Type byte
const (
DatagramTypeUDP DatagramV2Type = iota
DatagramTypeIP
)
const (
typeIDLen = 1
// Same as sessionDemuxChan capacity
packetChanCapacity = 128
)
func SuffixType(b []byte, datagramType DatagramV2Type) ([]byte, error) {
if len(b)+typeIDLen > MaxDatagramFrameSize {
return nil, fmt.Errorf("datagram size %d exceeds max frame size %d", len(b), MaxDatagramFrameSize)
}
b = append(b, byte(datagramType))
return b, nil
}
// Maximum application payload to send to / receive from QUIC datagram frame
func (dm *DatagramMuxerV2) mtu() int {
return maxDatagramPayloadSize
}
type DatagramMuxerV2 struct {
session quic.Connection
logger *zerolog.Logger
sessionDemuxChan chan<- *packet.Session
packetDemuxChan chan packet.RawPacket
}
func NewDatagramMuxerV2(
quicSession quic.Connection,
log *zerolog.Logger,
sessionDemuxChan chan<- *packet.Session,
) *DatagramMuxerV2 {
logger := log.With().Uint8("datagramVersion", 2).Logger()
return &DatagramMuxerV2{
session: quicSession,
logger: &logger,
sessionDemuxChan: sessionDemuxChan,
packetDemuxChan: make(chan packet.RawPacket, packetChanCapacity),
}
}
// SendToSession suffix the session ID and datagram version to the payload so the other end of the QUIC connection can
// demultiplex the payload from multiple datagram sessions
func (dm *DatagramMuxerV2) SendToSession(session *packet.Session) error {
if len(session.Payload) > dm.mtu() {
packetTooBigDropped.Inc()
return fmt.Errorf("origin UDP payload has %d bytes, which exceeds transport MTU %d", len(session.Payload), dm.mtu())
}
msgWithID, err := SuffixSessionID(session.ID, session.Payload)
if err != nil {
return errors.Wrap(err, "Failed to suffix session ID to datagram, it will be dropped")
}
msgWithIDAndType, err := SuffixType(msgWithID, DatagramTypeUDP)
if err != nil {
return errors.Wrap(err, "Failed to suffix datagram type, it will be dropped")
}
if err := dm.session.SendMessage(msgWithIDAndType); err != nil {
return errors.Wrap(err, "Failed to send datagram back to edge")
}
return nil
}
// SendPacket suffix the datagram type to the packet. The other end of the QUIC connection can demultiplex by parsing
// the payload as IP and look at the source and destination.
func (dm *DatagramMuxerV2) SendPacket(pk packet.RawPacket) error {
payloadWithVersion, err := SuffixType(pk.Data, DatagramTypeIP)
if err != nil {
return errors.Wrap(err, "Failed to suffix datagram type, it will be dropped")
}
if err := dm.session.SendMessage(payloadWithVersion); err != nil {
return errors.Wrap(err, "Failed to send datagram back to edge")
}
return nil
}
// Demux reads datagrams from the QUIC connection and demuxes depending on whether it's a session or packet
func (dm *DatagramMuxerV2) ServeReceive(ctx context.Context) error {
for {
msg, err := dm.session.ReceiveMessage()
if err != nil {
return err
}
if err := dm.demux(ctx, msg); err != nil {
dm.logger.Error().Err(err).Msg("Failed to demux datagram")
if err == context.Canceled {
return err
}
}
}
}
func (dm *DatagramMuxerV2) ReceivePacket(ctx context.Context) (packet.RawPacket, error) {
select {
case <-ctx.Done():
return packet.RawPacket{}, ctx.Err()
case pk := <-dm.packetDemuxChan:
return pk, nil
}
}
func (dm *DatagramMuxerV2) demux(ctx context.Context, msgWithType []byte) error {
if len(msgWithType) < typeIDLen {
return fmt.Errorf("QUIC datagram should have at least %d byte", typeIDLen)
}
msgType := DatagramV2Type(msgWithType[len(msgWithType)-typeIDLen])
msg := msgWithType[0 : len(msgWithType)-typeIDLen]
switch msgType {
case DatagramTypeUDP:
return dm.handleSession(ctx, msg)
case DatagramTypeIP:
return dm.handlePacket(ctx, msg)
default:
return fmt.Errorf("Unexpected datagram type %d", msgType)
}
}
func (dm *DatagramMuxerV2) handleSession(ctx context.Context, session []byte) error {
sessionID, payload, err := extractSessionID(session)
if err != nil {
return err
}
sessionDatagram := packet.Session{
ID: sessionID,
Payload: payload,
}
select {
case dm.sessionDemuxChan <- &sessionDatagram:
return nil
case <-ctx.Done():
return ctx.Err()
}
}
func (dm *DatagramMuxerV2) handlePacket(ctx context.Context, pk []byte) error {
select {
case <-ctx.Done():
return ctx.Err()
case dm.packetDemuxChan <- packet.RawPacket{
Data: pk,
}:
return nil
}
}