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) {
  52         active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]
  53         if ok {
  54                 active.Cancel()
  55         }
  56         if !ws.peer.deleteRequest(r) {
  57                 panic("cancelled webseed request should exist")
  58         }
  59         if ws.peer.isLowOnRequests() {
  60                 ws.peer.updateRequests("webseedPeer._cancel")
  61         }
  62 }
  63
  64 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  65         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  66 }
  67
  68 func (ws *webseedPeer) _request(r Request) bool {
  69         ws.requesterCond.Signal()
  70         return true
  71 }
  72
  73 func (ws *webseedPeer) doRequest(r Request) error {
  74         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  75         ws.activeRequests[r] = webseedRequest
  76         err := func() error {
  77                 ws.requesterCond.L.Unlock()
  78                 defer ws.requesterCond.L.Lock()
  79                 return ws.requestResultHandler(r, webseedRequest)
  80         }()
  81         delete(ws.activeRequests, r)
  82         return err
  83 }
  84
  85 func (ws *webseedPeer) requester(i int) {
  86         ws.requesterCond.L.Lock()
  87         defer ws.requesterCond.L.Unlock()
  88 start:
  89         for !ws.peer.closed.IsSet() {
  90                 restart := false
  91                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  92                         r := ws.peer.t.requestIndexToRequest(x)
  93                         if _, ok := ws.activeRequests[r]; ok {
  94                                 return true
  95                         }
  96                         err := ws.doRequest(r)
  97                         ws.requesterCond.L.Unlock()
  98                         if err != nil && !errors.Is(err, context.Canceled) {
  99                                 log.Printf("requester %v: error doing webseed request %v: %v", i, r, err)
 100                         }
 101                         restart = true
 102                         if errors.Is(err, webseed.ErrTooFast) {
 103                                 time.Sleep(time.Duration(rand.Int63n(int64(10 * time.Second))))
 104                         }
 105                         ws.requesterCond.L.Lock()
 106                         return false
 107                 })
 108                 if restart {
 109                         goto start
 110                 }
 111                 ws.requesterCond.Wait()
 112         }
 113 }
 114
 115 func (ws *webseedPeer) connectionFlags() string {
 116         return "WS"
 117 }
 118
 119 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 120 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 121 func (ws *webseedPeer) drop() {}
 122
 123 func (ws *webseedPeer) handleUpdateRequests() {
 124         // Because this is synchronous, webseed peers seem to get first dibs on newly prioritized
 125         // pieces.
 126         go func() {
 127                 ws.peer.t.cl.lock()
 128                 defer ws.peer.t.cl.unlock()
 129                 ws.peer.maybeUpdateActualRequestState()
 130         }()
 131 }
 132
 133 func (ws *webseedPeer) onClose() {
 134         ws.peer.logger.WithLevel(log.Debug).Print("closing")
 135         ws.peer.deleteAllRequests()
 136         for _, r := range ws.activeRequests {
 137                 r.Cancel()
 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                 ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 174                 return err
 175         }
 176         err = ws.peer.receiveChunk(&pp.Message{
 177                 Type:  pp.Piece,
 178                 Index: r.Index,
 179                 Begin: r.Begin,
 180                 Piece: result.Bytes,
 181         })
 182         if err != nil {
 183                 panic(err)
 184         }
 185         return err
 186 }
 187
 188 func (me *webseedPeer) isLowOnRequests() bool {
 189         return me.peer.actualRequestState.Requests.GetCardinality() < uint64(me.maxRequests)
 190 }
 191
 192 func (me *webseedPeer) peerPieces() *roaring.Bitmap {
 193         return &me.client.Pieces
 194 }
 195
 196 func (cn *webseedPeer) peerHasAllPieces() (all, known bool) {
 197         if !cn.peer.t.haveInfo() {
 198                 return true, false
 199         }
 200         return cn.client.Pieces.GetCardinality() == uint64(cn.peer.t.numPieces()), true
 201 }