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peer.go
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peer.go
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package moqtransport
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"log"
"time"
"github.com/danielpfeifer02/priority-moqtransport/varint"
"golang.org/x/exp/slices"
)
var (
errUnexpectedMessage = errors.New("got unexpected message")
errInvalidTrackNamespace = errors.New("got invalid tracknamespace")
errClosed = errors.New("connection was closed")
errUnsupportedVersion = errors.New("unsupported version")
errMissingRoleParameter = errors.New("missing role parameter")
errGoAway = errors.New("received go away from peer")
)
// TODO: Streams must be wrapped properly for quic and webtransport The
// interfaces need to add CancelRead and CancelWrite for STOP_SENDING and
// RESET_STREAM purposes. The interface should allow implementations for quic
// and webtransport.
type stream interface {
readStream
sendStream
}
type readStream interface {
io.Reader
}
type sendStream interface {
io.WriteCloser
}
type connection interface {
OpenStream() (stream, error)
OpenStreamSync(context.Context) (stream, error)
OpenUniStream() (sendStream, error)
OpenUniStreamSync(context.Context) (sendStream, error)
AcceptStream(context.Context) (stream, error)
AcceptUniStream(context.Context) (readStream, error)
ReceiveMessage(context.Context) ([]byte, error)
CloseWithError(uint64, string) error
}
type SubscriptionHandler func(string, *SendTrack) (uint64, time.Duration, error)
type AnnouncementHandler func(string) error
type Peer struct {
conn connection
inMsgCh chan message
ctrlMessageCh chan message
ctrlStream stream
role role
receiveTracks map[uint64]*ReceiveTrack
sendTracks map[string]*SendTrack
subscribeHandler SubscriptionHandler
announcementHandler AnnouncementHandler
closeCh chan struct{}
}
func newServerPeer(ctx context.Context, conn connection) (*Peer, error) {
s, err := conn.AcceptStream(ctx)
if err != nil {
return nil, err
}
m, err := readNext(varint.NewReader(s), serverRole)
if err != nil {
return nil, err
}
msg, ok := m.(*clientSetupMessage)
if !ok {
return nil, errUnexpectedMessage
}
// TODO: Algorithm to select best matching version
if !slices.Contains(msg.supportedVersions, DRAFT_IETF_MOQ_TRANSPORT_00) {
return nil, errUnsupportedVersion
}
_, ok = msg.setupParameters[roleParameterKey]
if !ok {
return nil, errMissingRoleParameter
}
// TODO: save role parameter
ssm := serverSetupMessage{
selectedVersion: DRAFT_IETF_MOQ_TRANSPORT_00,
setupParameters: map[parameterKey]parameter{},
}
buf := ssm.append(make([]byte, 0, 1500))
_, err = s.Write(buf)
if err != nil {
return nil, err
}
p := &Peer{
conn: conn,
inMsgCh: make(chan message),
ctrlMessageCh: make(chan message),
ctrlStream: s,
role: serverRole,
receiveTracks: map[uint64]*ReceiveTrack{},
sendTracks: map[string]*SendTrack{},
subscribeHandler: nil,
announcementHandler: nil,
closeCh: make(chan struct{}),
}
return p, nil
}
func (p *Peer) run(ctx context.Context, enableDatagrams bool) error {
errCh := make(chan error)
ctx, cancel := context.WithCancel(ctx)
defer cancel()
fs := []func(context.Context) error{
p.controlStreamLoop,
p.acceptUnidirectionalStreams,
p.acceptBidirectionalStreams,
}
if enableDatagrams {
fs = append(fs, p.acceptDatagrams)
}
for _, f := range fs {
go func(ctx context.Context, f func(context.Context) error, ch chan<- error) {
if err := f(ctx); err != nil {
ch <- err
}
}(ctx, f, errCh)
}
select {
case <-ctx.Done():
return nil
case err := <-errCh:
return err
}
}
func newClientPeer(ctx context.Context, conn connection, enableDatagrams bool) (*Peer, error) {
s, err := conn.OpenStreamSync(ctx)
if err != nil {
return nil, err
}
csm := clientSetupMessage{
supportedVersions: []version{version(DRAFT_IETF_MOQ_TRANSPORT_00)},
setupParameters: map[parameterKey]parameter{
roleParameterKey: ingestionDeliveryRole,
},
}
buf := csm.append(make([]byte, 0, 1500))
_, err = s.Write(buf)
if err != nil {
return nil, err
}
p := &Peer{
conn: conn,
inMsgCh: make(chan message),
ctrlMessageCh: make(chan message),
ctrlStream: s,
role: clientRole,
receiveTracks: map[uint64]*ReceiveTrack{},
sendTracks: map[string]*SendTrack{},
subscribeHandler: nil,
announcementHandler: nil,
closeCh: make(chan struct{}),
}
m, err := readNext(varint.NewReader(s), clientRole)
if err != nil {
return nil, err
}
ssm, ok := m.(*serverSetupMessage)
if !ok {
return nil, errUnexpectedMessage
}
if !slices.Contains(csm.supportedVersions, ssm.selectedVersion) {
return nil, errUnsupportedVersion
}
// TODO: Handle error and propagate it to the user?
go p.run(ctx, enableDatagrams)
return p, nil
}
func (p *Peer) readMessages(r messageReader, stream io.Reader) error {
for {
msg, err := readNext(r, p.role)
if err != nil {
return err
}
object, ok := msg.(*objectMessage)
if !ok {
return errUnexpectedMessage
}
p.handleObjectMessage(object)
}
}
type messageKey struct {
mt messageType
id string
}
type keyer interface {
key() messageKey
}
type keyedMessage interface {
message
keyer
}
type responseHandler interface {
handle(message)
}
type keyedResponseHandler interface {
keyedMessage
responseHandler
}
func (p *Peer) controlStreamLoop(ctx context.Context) error {
inCh := make(chan message)
errCh := make(chan error)
transactions := make(map[messageKey]keyedMessage)
go func(s stream, ch chan<- message, errCh chan<- error) {
for {
msg, err := readNext(varint.NewReader(s), p.role)
if err != nil {
errCh <- err
return
}
ch <- msg
}
}(p.ctrlStream, inCh, errCh)
for {
select {
case m := <-inCh:
log.Printf("handling %v\n", m)
switch v := m.(type) {
case *subscribeRequestMessage:
go func() {
p.ctrlMessageCh <- p.handleSubscribeRequest(v)
}()
case *announceMessage:
go func() {
p.ctrlMessageCh <- p.handleAnnounceMessage(v)
}()
case *goAwayMessage:
return errGoAway
case keyedMessage:
t, ok := transactions[v.key()]
if !ok {
// TODO: Error: This an error, because all keyed messages
// that occur without responding to a transaction started by
// us should be handled by the case above. I.e., if we get
// an Ok or Error for Announce or subscribe, that should
// only happen when we also stored an associated transaction
// earlier.
return errors.New("unexpected unkeyed message")
}
rh, ok := t.(responseHandler)
if !ok {
return errors.New("unexpected message without responseHandler")
}
rh.handle(v)
default:
return errUnexpectedMessage
}
case m := <-p.ctrlMessageCh:
if krh, ok := m.(keyedResponseHandler); ok {
transactions[krh.key()] = krh
}
buf := make([]byte, 0, 1500)
buf = m.append(buf)
_, err := p.ctrlStream.Write(buf)
if err != nil {
return err
}
case err := <-errCh:
return err
}
}
}
func (p *Peer) acceptBidirectionalStreams(ctx context.Context) error {
for {
s, err := p.conn.AcceptStream(ctx)
if err != nil {
return err
}
go func() {
if err := p.readMessages(varint.NewReader(s), s); err != nil {
panic(err)
}
}()
}
}
func (p *Peer) acceptUnidirectionalStreams(ctx context.Context) error {
for {
stream, err := p.conn.AcceptUniStream(ctx)
if err != nil {
return err
}
go func() {
if err := p.readMessages(varint.NewReader(stream), stream); err != nil {
panic(err)
}
}()
}
}
func (p *Peer) acceptDatagrams(ctx context.Context) error {
for {
dgram, err := p.conn.ReceiveMessage(ctx)
if err != nil {
return err
}
r := bytes.NewReader(dgram)
go func() {
if err := p.readMessages(r, nil); err != nil {
panic(err)
}
}()
}
}
func (p *Peer) handleObjectMessage(msg *objectMessage) error {
t, ok := p.receiveTracks[msg.trackID]
if !ok {
// handle unknown track?
panic("TODO 1 (unknown track)")
}
t.push(msg)
return nil
}
func (p *Peer) handleSubscribeRequest(msg *subscribeRequestMessage) message {
if p.subscribeHandler == nil {
// TODONOW: does that fix it? is subscription handler set by go routine?s
time.Sleep(10 * time.Millisecond)
if p.subscribeHandler == nil {
panic("TODO 2 (no subscribe handler)")
}
}
t := newSendTrack(p.conn)
p.sendTracks[msg.fullTrackName] = t
id, expires, err := p.subscribeHandler(msg.fullTrackName, t)
if err != nil {
log.Println(err)
return &subscribeErrorMessage{
fullTrackName: msg.fullTrackName,
errorCode: GenericErrorCode,
reasonPhrase: "failed to handle subscription",
}
}
fmt.Println("Subscription id is", id)
t.id = id
return &subscribeOkMessage{
fullTrackName: msg.fullTrackName,
trackID: id,
expires: expires,
}
}
func (p *Peer) handleAnnounceMessage(msg *announceMessage) message {
if p.announcementHandler == nil {
panic("TODO 3 (no announcement handler)")
}
if err := p.announcementHandler(msg.trackNamespace); err != nil {
return &announceErrorMessage{
trackNamespace: msg.trackNamespace,
errorCode: 0,
reasonPhrase: "failed to handle announcement",
}
}
return &announceOkMessage{
trackNamespace: msg.trackNamespace,
}
}
type ctrlMessage struct {
keyedMessage
responseCh chan message
}
func (m *ctrlMessage) handle(msg message) {
m.responseCh <- msg
}
func (p *Peer) Announce(namespace string) error {
if len(namespace) == 0 {
return errInvalidTrackNamespace
}
am := &announceMessage{
trackNamespace: namespace,
trackRequestParameters: map[parameterKey]parameter{},
}
responseCh := make(chan message)
select {
case p.ctrlMessageCh <- &ctrlMessage{
keyedMessage: am,
responseCh: responseCh,
}:
case <-p.closeCh:
return errClosed
}
var resp message
select {
case resp = <-responseCh:
case <-time.After(time.Second): // TODO: Make timeout configurable?
panic("TODO: timeout error 1 (no response after announce message sent)")
case <-p.closeCh:
return errClosed
}
switch v := resp.(type) {
case *announceOkMessage:
if v.trackNamespace != am.trackNamespace {
panic("TODO 4 (trackNamespace mismatch for announceOkMessage)")
}
case *announceErrorMessage:
return errors.New(v.reasonPhrase) // TODO: Wrap error string?
default:
return errUnexpectedMessage
}
return nil
}
func (p *Peer) Subscribe(trackname string) (*ReceiveTrack, error) {
sm := &subscribeRequestMessage{
fullTrackName: trackname,
trackRequestParameters: map[parameterKey]parameter{},
}
responseCh := make(chan message)
select {
case p.ctrlMessageCh <- &ctrlMessage{
keyedMessage: sm,
responseCh: responseCh,
}:
case <-p.closeCh:
return nil, errClosed
case <-time.After(time.Second):
panic("TODO: timeout error 2 (no response when sending subscribe message)")
}
var resp message
select {
case resp = <-responseCh:
case <-time.After(time.Second): // TODO: Make timeout configurable?
panic("TODO: timeout error 3 (no response after subscribe message sent)")
case <-p.closeCh:
return nil, errClosed
}
switch v := resp.(type) {
case *subscribeOkMessage:
if v.fullTrackName != sm.fullTrackName {
panic("TODO 5 (trackname mismatch for subscribeOkMessage)")
}
t := newReceiveTrack()
p.receiveTracks[v.trackID] = t
return t, nil
case *subscribeErrorMessage:
return nil, errors.New(v.reasonPhrase)
}
return nil, errUnexpectedMessage
}
func (p *Peer) OnAnnouncement(callback AnnouncementHandler) {
p.announcementHandler = callback
}
func (p *Peer) OnSubscription(callback SubscriptionHandler) {
p.subscribeHandler = callback
}
func (p *Peer) GetConnection() connection {
return p.conn
}