10 "github.com/anacrolix/log"
12 "github.com/anacrolix/torrent/tracker"
13 "github.com/gorilla/websocket"
14 "github.com/pion/datachannel"
15 "github.com/pion/webrtc/v3"
18 type TrackerClientStats struct {
20 ConvertedInboundConns int64
21 ConvertedOutboundConns int64
24 // Client represents the webtorrent client
25 type TrackerClient struct {
27 GetAnnounceRequest func(_ tracker.AnnounceEvent, infoHash [20]byte) (tracker.AnnounceRequest, error)
29 OnConn onDataChannelOpen
34 outboundOffers map[string]outboundOffer // OfferID to outboundOffer
35 wsConn *websocket.Conn
37 stats TrackerClientStats
38 pingTicker *time.Ticker
41 func (me *TrackerClient) Stats() TrackerClientStats {
47 func (me *TrackerClient) peerIdBinary() string {
48 return binaryToJsonString(me.PeerId[:])
51 // outboundOffer represents an outstanding offer.
52 type outboundOffer struct {
53 originalOffer webrtc.SessionDescription
54 peerConnection *wrappedPeerConnection
55 dataChannel *webrtc.DataChannel
59 type DataChannelContext struct {
60 Local, Remote webrtc.SessionDescription
66 type onDataChannelOpen func(_ datachannel.ReadWriteCloser, dcc DataChannelContext)
68 func (tc *TrackerClient) doWebsocket() error {
69 metrics.Add("websocket dials", 1)
73 c, _, err := websocket.DefaultDialer.Dial(tc.Url, nil)
75 return fmt.Errorf("dialing tracker: %w", err)
78 tc.Logger.WithDefaultLevel(log.Info).Printf("connected")
84 closeChan := make(chan struct{})
88 case <-tc.pingTicker.C:
90 err := c.WriteMessage(websocket.PingMessage, []byte{})
101 err = tc.trackerReadLoop(tc.wsConn)
109 // Finishes initialization and spawns the run routine, calling onStop when it completes with the
110 // result. We don't let the caller just spawn the runner directly, since then we can race against
111 // .Close to finish initialization.
112 func (tc *TrackerClient) Start(onStop func(error)) {
113 tc.pingTicker = time.NewTicker(60 * time.Second)
120 func (tc *TrackerClient) run() error {
124 err := tc.doWebsocket()
131 tc.Logger.WithDefaultLevel(level).Printf("websocket instance ended: %v", err)
132 time.Sleep(time.Minute)
139 func (tc *TrackerClient) Close() error {
142 if tc.wsConn != nil {
145 tc.closeUnusedOffers()
152 func (tc *TrackerClient) announceOffers() {
153 // tc.Announce grabs a lock on tc.outboundOffers. It also handles the case where outboundOffers
154 // is nil. Take ownership of outboundOffers here.
156 offers := tc.outboundOffers
157 tc.outboundOffers = nil
164 // Iterate over our locally-owned offers, close any existing "invalid" ones from before the
165 // socket reconnected, reannounce the infohash, adding it back into the tc.outboundOffers.
166 tc.Logger.WithDefaultLevel(log.Info).Printf("reannouncing %d infohashes after restart", len(offers))
167 for _, offer := range offers {
168 // TODO: Capture the errors? Are we even in a position to do anything with them?
169 offer.peerConnection.Close()
170 // Use goroutine here to allow read loop to start and ensure the buffer drains.
171 go tc.Announce(tracker.Started, offer.infoHash)
175 func (tc *TrackerClient) closeUnusedOffers() {
176 for _, offer := range tc.outboundOffers {
177 offer.peerConnection.Close()
179 tc.outboundOffers = nil
182 func (tc *TrackerClient) Announce(event tracker.AnnounceEvent, infoHash [20]byte) error {
183 metrics.Add("outbound announces", 1)
184 var randOfferId [20]byte
185 _, err := rand.Read(randOfferId[:])
187 return fmt.Errorf("generating offer_id bytes: %w", err)
189 offerIDBinary := binaryToJsonString(randOfferId[:])
191 pc, dc, offer, err := newOffer()
193 return fmt.Errorf("creating offer: %w", err)
196 request, err := tc.GetAnnounceRequest(event, infoHash)
199 return fmt.Errorf("getting announce parameters: %w", err)
202 req := AnnounceRequest{
203 Numwant: 1, // If higher we need to create equal amount of offers.
204 Uploaded: request.Uploaded,
205 Downloaded: request.Downloaded,
207 Event: request.Event.String(),
209 InfoHash: binaryToJsonString(infoHash[:]),
210 PeerID: tc.peerIdBinary(),
212 OfferID: offerIDBinary,
217 data, err := json.Marshal(req)
220 return fmt.Errorf("marshalling request: %w", err)
225 err = tc.writeMessage(data)
228 return fmt.Errorf("write AnnounceRequest: %w", err)
230 if tc.outboundOffers == nil {
231 tc.outboundOffers = make(map[string]outboundOffer)
233 tc.outboundOffers[offerIDBinary] = outboundOffer{
236 originalOffer: offer,
242 func (tc *TrackerClient) writeMessage(data []byte) error {
243 for tc.wsConn == nil {
245 return fmt.Errorf("%T closed", tc)
249 return tc.wsConn.WriteMessage(websocket.TextMessage, data)
252 func (tc *TrackerClient) trackerReadLoop(tracker *websocket.Conn) error {
254 _, message, err := tracker.ReadMessage()
256 return fmt.Errorf("read message error: %w", err)
258 // tc.Logger.WithDefaultLevel(log.Debug).Printf("received message from tracker: %q", message)
260 var ar AnnounceResponse
261 if err := json.Unmarshal(message, &ar); err != nil {
262 tc.Logger.WithDefaultLevel(log.Warning).Printf("error unmarshalling announce response: %v", err)
266 case ar.Offer != nil:
267 ih, err := jsonStringToInfoHash(ar.InfoHash)
269 tc.Logger.WithDefaultLevel(log.Warning).Printf("error decoding info_hash in offer: %v", err)
272 tc.handleOffer(*ar.Offer, ar.OfferID, ih, ar.PeerID)
273 case ar.Answer != nil:
274 tc.handleAnswer(ar.OfferID, *ar.Answer)
279 func (tc *TrackerClient) handleOffer(
280 offer webrtc.SessionDescription,
285 peerConnection, answer, err := newAnsweringPeerConnection(offer)
287 return fmt.Errorf("write AnnounceResponse: %w", err)
289 response := AnnounceResponse{
291 InfoHash: binaryToJsonString(infoHash[:]),
292 PeerID: tc.peerIdBinary(),
297 data, err := json.Marshal(response)
299 peerConnection.Close()
300 return fmt.Errorf("marshalling response: %w", err)
304 if err := tc.writeMessage(data); err != nil {
305 peerConnection.Close()
306 return fmt.Errorf("writing response: %w", err)
308 timer := time.AfterFunc(30*time.Second, func() {
309 metrics.Add("answering peer connections timed out", 1)
310 peerConnection.Close()
312 peerConnection.OnDataChannel(func(d *webrtc.DataChannel) {
313 setDataChannelOnOpen(d, peerConnection, func(dc datachannel.ReadWriteCloser) {
315 metrics.Add("answering peer connection conversions", 1)
317 tc.stats.ConvertedInboundConns++
319 tc.OnConn(dc, DataChannelContext{
331 func (tc *TrackerClient) handleAnswer(offerId string, answer webrtc.SessionDescription) {
334 offer, ok := tc.outboundOffers[offerId]
336 tc.Logger.WithDefaultLevel(log.Warning).Printf("could not find offer for id %+q", offerId)
339 // tc.Logger.WithDefaultLevel(log.Debug).Printf("offer %q got answer %v", offerId, answer)
340 metrics.Add("outbound offers answered", 1)
341 err := offer.setAnswer(answer, func(dc datachannel.ReadWriteCloser) {
342 metrics.Add("outbound offers answered with datachannel", 1)
344 tc.stats.ConvertedOutboundConns++
346 tc.OnConn(dc, DataChannelContext{
347 Local: offer.originalOffer,
351 InfoHash: offer.infoHash,
355 tc.Logger.WithDefaultLevel(log.Warning).Printf("error using outbound offer answer: %v", err)
358 delete(tc.outboundOffers, offerId)
359 go tc.Announce(tracker.None, offer.infoHash)