webseed-peer.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "errors"
   6         "fmt"
   7         "net/http"
   8         "strings"
   9         "sync"
  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 }
  40
  41 func (ws *webseedPeer) writeInterested(interested bool) bool {
  42         return true
  43 }
  44
  45 func (ws *webseedPeer) _cancel(r RequestIndex) bool {
  46         active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]
  47         if ok {
  48                 active.Cancel()
  49                 if !ws.peer.deleteRequest(r) {
  50                         panic("cancelled webseed request should exist")
  51                 }
  52                 if ws.peer.isLowOnRequests() {
  53                         ws.peer.updateRequests("webseedPeer._cancel")
  54                 }
  55         }
  56         return true
  57 }
  58
  59 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  60         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  61 }
  62
  63 func (ws *webseedPeer) _request(r Request) bool {
  64         ws.requesterCond.Signal()
  65         return true
  66 }
  67
  68 func (ws *webseedPeer) doRequest(r Request) {
  69         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  70         ws.activeRequests[r] = webseedRequest
  71         func() {
  72                 ws.requesterCond.L.Unlock()
  73                 defer ws.requesterCond.L.Lock()
  74                 ws.requestResultHandler(r, webseedRequest)
  75         }()
  76         delete(ws.activeRequests, r)
  77 }
  78
  79 func (ws *webseedPeer) requester() {
  80         ws.requesterCond.L.Lock()
  81         defer ws.requesterCond.L.Unlock()
  82 start:
  83         for !ws.peer.closed.IsSet() {
  84                 restart := false
  85                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  86                         r := ws.peer.t.requestIndexToRequest(x)
  87                         if _, ok := ws.activeRequests[r]; ok {
  88                                 return true
  89                         }
  90                         ws.doRequest(r)
  91                         restart = true
  92                         return false
  93                 })
  94                 if restart {
  95                         goto start
  96                 }
  97                 ws.requesterCond.Wait()
  98         }
  99 }
 100
 101 func (ws *webseedPeer) connectionFlags() string {
 102         return "WS"
 103 }
 104
 105 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 106 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 107 func (ws *webseedPeer) drop() {}
 108
 109 func (ws *webseedPeer) handleUpdateRequests() {
 110         ws.peer.maybeUpdateActualRequestState()
 111 }
 112
 113 func (ws *webseedPeer) onClose() {
 114         ws.peer.logger.WithLevel(log.Debug).Print("closing")
 115         for _, r := range ws.activeRequests {
 116                 r.Cancel()
 117         }
 118         ws.requesterCond.Broadcast()
 119 }
 120
 121 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 122         result := <-webseedRequest.Result
 123         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 124         // sure if we can divine which errors indicate cancellation on our end without hitting the
 125         // network though.
 126         ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 127         ws.peer.readBytes(int64(len(result.Bytes)))
 128         ws.peer.t.cl.lock()
 129         defer ws.peer.t.cl.unlock()
 130         if result.Err != nil {
 131                 if !errors.Is(result.Err, context.Canceled) {
 132                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 133                 }
 134                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 135                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 136                 const closeOnAllErrors = false
 137                 if closeOnAllErrors ||
 138                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 139                         func() bool {
 140                                 var err webseed.ErrBadResponse
 141                                 if !errors.As(result.Err, &err) {
 142                                         return false
 143                                 }
 144                                 return err.Response.StatusCode == http.StatusNotFound
 145                         }() {
 146                         ws.peer.close()
 147                 } else {
 148                         ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 149                 }
 150         } else {
 151                 err := ws.peer.receiveChunk(&pp.Message{
 152                         Type:  pp.Piece,
 153                         Index: r.Index,
 154                         Begin: r.Begin,
 155                         Piece: result.Bytes,
 156                 })
 157                 if err != nil {
 158                         panic(err)
 159                 }
 160         }
 161 }
 162
 163 func (me *webseedPeer) isLowOnRequests() bool {
 164         return me.peer.actualRequestState.Requests.GetCardinality() < uint64(me.maxRequests)
 165 }
 166
 167 func (me *webseedPeer) peerPieces() *roaring.Bitmap {
 168         return &me.client.Pieces
 169 }
 170
 171 func (cn *webseedPeer) peerHasAllPieces() (all, known bool) {
 172         if !cn.peer.t.haveInfo() {
 173                 return true, false
 174         }
 175         return cn.client.Pieces.GetCardinality() == uint64(cn.peer.t.numPieces()), true
 176 }