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         // First field for stats alignment.
  20         peer           Peer
  21         client         webseed.Client
  22         activeRequests map[Request]webseed.Request
  23         requesterCond  sync.Cond
  24         // Number of requester routines.
  25         maxRequests int
  26 }
  27
  28 var _ peerImpl = (*webseedPeer)(nil)
  29
  30 func (me *webseedPeer) connStatusString() string {
  31         return me.client.Url
  32 }
  33
  34 func (ws *webseedPeer) String() string {
  35         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  36 }
  37
  38 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  39         ws.client.SetInfo(info)
  40         // There should be probably be a callback in Client instead, so it can remove pieces at its whim
  41         // too.
  42         ws.client.Pieces.Iterate(func(x uint32) bool {
  43                 ws.peer.t.incPieceAvailability(pieceIndex(x))
  44                 return true
  45         })
  46 }
  47
  48 func (ws *webseedPeer) writeInterested(interested bool) bool {
  49         return true
  50 }
  51
  52 func (ws *webseedPeer) _cancel(r RequestIndex) bool {
  53         if active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]; ok {
  54                 active.Cancel()
  55                 // The requester is running and will handle the result.
  56                 return true
  57         }
  58         // There should be no requester handling this, so no further events will occur.
  59         return false
  60 }
  61
  62 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  63         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  64 }
  65
  66 func (ws *webseedPeer) _request(r Request) bool {
  67         ws.requesterCond.Signal()
  68         return true
  69 }
  70
  71 func (ws *webseedPeer) doRequest(r Request) error {
  72         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  73         ws.activeRequests[r] = webseedRequest
  74         err := func() error {
  75                 ws.requesterCond.L.Unlock()
  76                 defer ws.requesterCond.L.Lock()
  77                 return ws.requestResultHandler(r, webseedRequest)
  78         }()
  79         delete(ws.activeRequests, r)
  80         return err
  81 }
  82
  83 func (ws *webseedPeer) requester(i int) {
  84         ws.requesterCond.L.Lock()
  85         defer ws.requesterCond.L.Unlock()
  86 start:
  87         for !ws.peer.closed.IsSet() {
  88                 restart := false
  89                 ws.peer.requestState.Requests.Iterate(func(x uint32) bool {
  90                         r := ws.peer.t.requestIndexToRequest(x)
  91                         if _, ok := ws.activeRequests[r]; ok {
  92                                 return true
  93                         }
  94                         err := ws.doRequest(r)
  95                         ws.requesterCond.L.Unlock()
  96                         if err != nil && !errors.Is(err, context.Canceled) {
  97                                 log.Printf("requester %v: error doing webseed request %v: %v", i, r, err)
  98                         }
  99                         restart = true
 100                         if errors.Is(err, webseed.ErrTooFast) {
 101                                 time.Sleep(time.Duration(rand.Int63n(int64(10 * time.Second))))
 102                         }
 103                         ws.requesterCond.L.Lock()
 104                         return false
 105                 })
 106                 if restart {
 107                         goto start
 108                 }
 109                 ws.requesterCond.Wait()
 110         }
 111 }
 112
 113 func (ws *webseedPeer) connectionFlags() string {
 114         return "WS"
 115 }
 116
 117 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 118 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 119 func (ws *webseedPeer) drop() {}
 120
 121 func (ws *webseedPeer) handleUpdateRequests() {
 122         // Because this is synchronous, webseed peers seem to get first dibs on newly prioritized
 123         // pieces.
 124         go func() {
 125                 ws.peer.t.cl.lock()
 126                 defer ws.peer.t.cl.unlock()
 127                 ws.peer.maybeUpdateActualRequestState()
 128         }()
 129 }
 130
 131 func (ws *webseedPeer) onClose() {
 132         ws.peer.logger.Levelf(log.Debug, "closing")
 133         // Just deleting them means we would have to manually cancel active requests.
 134         ws.peer.cancelAllRequests()
 135         ws.peer.t.iterPeers(func(p *Peer) {
 136                 if p.isLowOnRequests() {
 137                         p.updateRequests("webseedPeer.onClose")
 138                 }
 139         })
 140         ws.requesterCond.Broadcast()
 141 }
 142
 143 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) error {
 144         result := <-webseedRequest.Result
 145         close(webseedRequest.Result) // one-shot
 146         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 147         // sure if we can divine which errors indicate cancellation on our end without hitting the
 148         // network though.
 149         if len(result.Bytes) != 0 || result.Err == nil {
 150                 // Increment ChunksRead and friends
 151                 ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 152         }
 153         ws.peer.readBytes(int64(len(result.Bytes)))
 154         ws.peer.t.cl.lock()
 155         defer ws.peer.t.cl.unlock()
 156         if ws.peer.t.closed.IsSet() {
 157                 return nil
 158         }
 159         err := result.Err
 160         if err != nil {
 161                 switch {
 162                 case errors.Is(err, context.Canceled):
 163                 case errors.Is(err, webseed.ErrTooFast):
 164                 case ws.peer.closed.IsSet():
 165                 default:
 166                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 167                         // // Here lies my attempt to extract something concrete from Go's error system. RIP.
 168                         // cfg := spew.NewDefaultConfig()
 169                         // cfg.DisableMethods = true
 170                         // cfg.Dump(result.Err)
 171                         log.Printf("closing %v", ws)
 172                         ws.peer.close()
 173                 }
 174                 if !ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r)) {
 175                         panic("invalid reject")
 176                 }
 177                 return err
 178         }
 179         err = ws.peer.receiveChunk(&pp.Message{
 180                 Type:  pp.Piece,
 181                 Index: r.Index,
 182                 Begin: r.Begin,
 183                 Piece: result.Bytes,
 184         })
 185         if err != nil {
 186                 panic(err)
 187         }
 188         return err
 189 }
 190
 191 func (me *webseedPeer) peerPieces() *roaring.Bitmap {
 192         return &me.client.Pieces
 193 }
 194
 195 func (cn *webseedPeer) peerHasAllPieces() (all, known bool) {
 196         if !cn.peer.t.haveInfo() {
 197                 return true, false
 198         }
 199         return cn.client.Pieces.GetCardinality() == uint64(cn.peer.t.numPieces()), true
 200 }