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         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         return true
  63 }
  64
  65 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  66         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  67 }
  68
  69 func (ws *webseedPeer) _request(r Request) bool {
  70         ws.requesterCond.Signal()
  71         return true
  72 }
  73
  74 func (ws *webseedPeer) doRequest(r Request) error {
  75         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  76         ws.activeRequests[r] = webseedRequest
  77         err := func() error {
  78                 ws.requesterCond.L.Unlock()
  79                 defer ws.requesterCond.L.Lock()
  80                 return ws.requestResultHandler(r, webseedRequest)
  81         }()
  82         delete(ws.activeRequests, r)
  83         return err
  84 }
  85
  86 func (ws *webseedPeer) requester(i int) {
  87         ws.requesterCond.L.Lock()
  88         defer ws.requesterCond.L.Unlock()
  89 start:
  90         for !ws.peer.closed.IsSet() {
  91                 restart := false
  92                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  93                         r := ws.peer.t.requestIndexToRequest(x)
  94                         if _, ok := ws.activeRequests[r]; ok {
  95                                 return true
  96                         }
  97                         err := ws.doRequest(r)
  98                         ws.requesterCond.L.Unlock()
  99                         if err != nil {
 100                                 log.Printf("requester %v: error doing webseed request %v: %v", i, r, err)
 101                         }
 102                         restart = true
 103                         if errors.Is(err, webseed.ErrTooFast) {
 104                                 time.Sleep(time.Duration(rand.Int63n(int64(10 * time.Second))))
 105                         }
 106                         ws.requesterCond.L.Lock()
 107                         return false
 108                 })
 109                 if restart {
 110                         goto start
 111                 }
 112                 ws.requesterCond.Wait()
 113         }
 114 }
 115
 116 func (ws *webseedPeer) connectionFlags() string {
 117         return "WS"
 118 }
 119
 120 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 121 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 122 func (ws *webseedPeer) drop() {}
 123
 124 func (ws *webseedPeer) handleUpdateRequests() {
 125         // Because this is synchronous, webseed peers seem to get first dibs on newly prioritized
 126         // pieces.
 127         ws.peer.maybeUpdateActualRequestState()
 128 }
 129
 130 func (ws *webseedPeer) onClose() {
 131         ws.peer.logger.WithLevel(log.Debug).Print("closing")
 132         ws.peer.deleteAllRequests()
 133         for _, r := range ws.activeRequests {
 134                 r.Cancel()
 135         }
 136         ws.requesterCond.Broadcast()
 137 }
 138
 139 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) error {
 140         result := <-webseedRequest.Result
 141         close(webseedRequest.Result) // one-shot
 142         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 143         // sure if we can divine which errors indicate cancellation on our end without hitting the
 144         // network though.
 145         if len(result.Bytes) != 0 || result.Err == nil {
 146                 // Increment ChunksRead and friends
 147                 ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 148         }
 149         ws.peer.readBytes(int64(len(result.Bytes)))
 150         ws.peer.t.cl.lock()
 151         defer ws.peer.t.cl.unlock()
 152         if ws.peer.t.closed.IsSet() {
 153                 return nil
 154         }
 155         err := result.Err
 156         if err != nil {
 157                 switch {
 158                 case errors.Is(err, context.Canceled):
 159                 case errors.Is(err, webseed.ErrTooFast):
 160                 case ws.peer.closed.IsSet():
 161                 default:
 162                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 163                         // // Here lies my attempt to extract something concrete from Go's error system. RIP.
 164                         // cfg := spew.NewDefaultConfig()
 165                         // cfg.DisableMethods = true
 166                         // cfg.Dump(result.Err)
 167                         log.Printf("closing %v", ws)
 168                         ws.peer.close()
 169                 }
 170                 ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 171                 return err
 172         }
 173         err = ws.peer.receiveChunk(&pp.Message{
 174                 Type:  pp.Piece,
 175                 Index: r.Index,
 176                 Begin: r.Begin,
 177                 Piece: result.Bytes,
 178         })
 179         if err != nil {
 180                 panic(err)
 181         }
 182         return err
 183 }
 184
 185 func (me *webseedPeer) isLowOnRequests() bool {
 186         return me.peer.actualRequestState.Requests.GetCardinality() < uint64(me.maxRequests)
 187 }
 188
 189 func (me *webseedPeer) peerPieces() *roaring.Bitmap {
 190         return &me.client.Pieces
 191 }
 192
 193 func (cn *webseedPeer) peerHasAllPieces() (all, known bool) {
 194         if !cn.peer.t.haveInfo() {
 195                 return true, false
 196         }
 197         return cn.client.Pieces.GetCardinality() == uint64(cn.peer.t.numPieces()), true
 198 }