webseed-peer.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "errors"
   6         "fmt"
   7         "math/rand"
   8         "sync"
   9         "time"
  10
  11         "github.com/RoaringBitmap/roaring"
  12         "github.com/anacrolix/log"
  13         "github.com/anacrolix/torrent/metainfo"
  14         pp "github.com/anacrolix/torrent/peer_protocol"
  15         "github.com/anacrolix/torrent/webseed"
  16 )
  17
  18 type webseedPeer struct {
  19         client         webseed.Client
  20         activeRequests map[Request]webseed.Request
  21         requesterCond  sync.Cond
  22         peer           Peer
  23         // Number of requester routines.
  24         maxRequests int
  25 }
  26
  27 var _ peerImpl = (*webseedPeer)(nil)
  28
  29 func (me *webseedPeer) connStatusString() string {
  30         return me.client.Url
  31 }
  32
  33 func (ws *webseedPeer) String() string {
  34         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  35 }
  36
  37 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  38         ws.client.SetInfo(info)
  39         // There should be probably be a callback in Client instead, so it can remove pieces at its whim
  40         // too.
  41         ws.client.Pieces.Iterate(func(x uint32) bool {
  42                 ws.peer.t.incPieceAvailability(pieceIndex(x))
  43                 return true
  44         })
  45 }
  46
  47 func (ws *webseedPeer) writeInterested(interested bool) bool {
  48         return true
  49 }
  50
  51 func (ws *webseedPeer) _cancel(r RequestIndex) bool {
  52         if active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]; ok {
  53                 active.Cancel()
  54                 // The requester is running and will handle the result.
  55                 return true
  56         }
  57         // There should be no requester handling this, so no further events will occur.
  58         return false
  59 }
  60
  61 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  62         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  63 }
  64
  65 func (ws *webseedPeer) _request(r Request) bool {
  66         ws.requesterCond.Signal()
  67         return true
  68 }
  69
  70 func (ws *webseedPeer) doRequest(r Request) error {
  71         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  72         ws.activeRequests[r] = webseedRequest
  73         err := func() error {
  74                 ws.requesterCond.L.Unlock()
  75                 defer ws.requesterCond.L.Lock()
  76                 return ws.requestResultHandler(r, webseedRequest)
  77         }()
  78         delete(ws.activeRequests, r)
  79         return err
  80 }
  81
  82 func (ws *webseedPeer) requester(i int) {
  83         ws.requesterCond.L.Lock()
  84         defer ws.requesterCond.L.Unlock()
  85 start:
  86         for !ws.peer.closed.IsSet() {
  87                 restart := false
  88                 ws.peer.requestState.Requests.Iterate(func(x uint32) bool {
  89                         r := ws.peer.t.requestIndexToRequest(x)
  90                         if _, ok := ws.activeRequests[r]; ok {
  91                                 return true
  92                         }
  93                         err := ws.doRequest(r)
  94                         ws.requesterCond.L.Unlock()
  95                         if err != nil && !errors.Is(err, context.Canceled) {
  96                                 log.Printf("requester %v: error doing webseed request %v: %v", i, r, err)
  97                         }
  98                         restart = true
  99                         if errors.Is(err, webseed.ErrTooFast) {
 100                                 time.Sleep(time.Duration(rand.Int63n(int64(10 * time.Second))))
 101                         }
 102                         ws.requesterCond.L.Lock()
 103                         return false
 104                 })
 105                 if restart {
 106                         goto start
 107                 }
 108                 ws.requesterCond.Wait()
 109         }
 110 }
 111
 112 func (ws *webseedPeer) connectionFlags() string {
 113         return "WS"
 114 }
 115
 116 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 117 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 118 func (ws *webseedPeer) drop() {}
 119
 120 func (ws *webseedPeer) handleUpdateRequests() {
 121         // Because this is synchronous, webseed peers seem to get first dibs on newly prioritized
 122         // pieces.
 123         go func() {
 124                 ws.peer.t.cl.lock()
 125                 defer ws.peer.t.cl.unlock()
 126                 ws.peer.maybeUpdateActualRequestState()
 127         }()
 128 }
 129
 130 func (ws *webseedPeer) onClose() {
 131         ws.peer.logger.Levelf(log.Debug, "closing")
 132         // Just deleting them means we would have to manually cancel active requests.
 133         ws.peer.cancelAllRequests()
 134         ws.peer.t.iterPeers(func(p *Peer) {
 135                 if p.isLowOnRequests() {
 136                         p.updateRequests("webseedPeer.onClose")
 137                 }
 138         })
 139         ws.requesterCond.Broadcast()
 140 }
 141
 142 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) error {
 143         result := <-webseedRequest.Result
 144         close(webseedRequest.Result) // one-shot
 145         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 146         // sure if we can divine which errors indicate cancellation on our end without hitting the
 147         // network though.
 148         if len(result.Bytes) != 0 || result.Err == nil {
 149                 // Increment ChunksRead and friends
 150                 ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 151         }
 152         ws.peer.readBytes(int64(len(result.Bytes)))
 153         ws.peer.t.cl.lock()
 154         defer ws.peer.t.cl.unlock()
 155         if ws.peer.t.closed.IsSet() {
 156                 return nil
 157         }
 158         err := result.Err
 159         if err != nil {
 160                 switch {
 161                 case errors.Is(err, context.Canceled):
 162                 case errors.Is(err, webseed.ErrTooFast):
 163                 case ws.peer.closed.IsSet():
 164                 default:
 165                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 166                         // // Here lies my attempt to extract something concrete from Go's error system. RIP.
 167                         // cfg := spew.NewDefaultConfig()
 168                         // cfg.DisableMethods = true
 169                         // cfg.Dump(result.Err)
 170                         log.Printf("closing %v", ws)
 171                         ws.peer.close()
 172                 }
 173                 if !ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r)) {
 174                         panic("invalid reject")
 175                 }
 176                 return err
 177         }
 178         err = ws.peer.receiveChunk(&pp.Message{
 179                 Type:  pp.Piece,
 180                 Index: r.Index,
 181                 Begin: r.Begin,
 182                 Piece: result.Bytes,
 183         })
 184         if err != nil {
 185                 panic(err)
 186         }
 187         return err
 188 }
 189
 190 func (me *webseedPeer) peerPieces() *roaring.Bitmap {
 191         return &me.client.Pieces
 192 }
 193
 194 func (cn *webseedPeer) peerHasAllPieces() (all, known bool) {
 195         if !cn.peer.t.haveInfo() {
 196                 return true, false
 197         }
 198         return cn.client.Pieces.GetCardinality() == uint64(cn.peer.t.numPieces()), true
 199 }