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/anacrolix/torrent/common"
  12         "github.com/anacrolix/torrent/metainfo"
  13         pp "github.com/anacrolix/torrent/peer_protocol"
  14         "github.com/anacrolix/torrent/segments"
  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 }
  24
  25 var _ peerImpl = (*webseedPeer)(nil)
  26
  27 func (me *webseedPeer) writeBufferFull() bool {
  28         return false
  29 }
  30
  31 func (me *webseedPeer) connStatusString() string {
  32         return me.client.Url
  33 }
  34
  35 func (ws *webseedPeer) String() string {
  36         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  37 }
  38
  39 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  40         ws.client.FileIndex = segments.NewIndex(common.LengthIterFromUpvertedFiles(info.UpvertedFiles()))
  41         ws.client.Info = info
  42 }
  43
  44 func (ws *webseedPeer) _postCancel(r Request) {
  45         ws.cancel(r)
  46 }
  47
  48 func (ws *webseedPeer) writeInterested(interested bool) bool {
  49         return true
  50 }
  51
  52 func (ws *webseedPeer) cancel(r Request) bool {
  53         active, ok := ws.activeRequests[r]
  54         if !ok {
  55                 return false
  56         }
  57         active.Cancel()
  58         return true
  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) {
  71         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  72         ws.activeRequests[r] = webseedRequest
  73         func() {
  74                 ws.requesterCond.L.Unlock()
  75                 defer ws.requesterCond.L.Lock()
  76                 ws.requestResultHandler(r, webseedRequest)
  77         }()
  78         delete(ws.activeRequests, r)
  79 }
  80
  81 func (ws *webseedPeer) requester() {
  82         ws.requesterCond.L.Lock()
  83         defer ws.requesterCond.L.Unlock()
  84 start:
  85         for !ws.peer.closed.IsSet() {
  86                 for r := range ws.peer.requests {
  87                         if _, ok := ws.activeRequests[r]; ok {
  88                                 continue
  89                         }
  90                         ws.doRequest(r)
  91                         goto start
  92                 }
  93                 ws.requesterCond.Wait()
  94         }
  95 }
  96
  97 func (ws *webseedPeer) connectionFlags() string {
  98         return "WS"
  99 }
 100
 101 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 102 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 103 func (ws *webseedPeer) drop() {}
 104
 105 func (ws *webseedPeer) updateRequests() {
 106 }
 107
 108 func (ws *webseedPeer) onClose() {
 109         ws.peer.logger.Print("closing")
 110         for _, r := range ws.activeRequests {
 111                 r.Cancel()
 112         }
 113         ws.requesterCond.Broadcast()
 114 }
 115
 116 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 117         result := <-webseedRequest.Result
 118         ws.peer.t.cl.lock()
 119         defer ws.peer.t.cl.unlock()
 120         if result.Err != nil {
 121                 if !errors.Is(result.Err, context.Canceled) {
 122                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 123                 }
 124                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 125                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 126                 const closeOnAllErrors = false
 127                 if closeOnAllErrors ||
 128                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 129                         func() bool {
 130                                 var err webseed.ErrBadResponse
 131                                 if !errors.As(result.Err, &err) {
 132                                         return false
 133                                 }
 134                                 return err.Response.StatusCode == http.StatusNotFound
 135                         }() {
 136                         ws.peer.close()
 137                 } else {
 138                         ws.peer.remoteRejectedRequest(r)
 139                 }
 140         } else {
 141                 err := ws.peer.receiveChunk(&pp.Message{
 142                         Type:  pp.Piece,
 143                         Index: r.Index,
 144                         Begin: r.Begin,
 145                         Piece: result.Bytes,
 146                 })
 147                 if err != nil {
 148                         panic(err)
 149                 }
 150         }
 151 }