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) writeInterested(interested bool) bool {
  45         return true
  46 }
  47
  48 func (ws *webseedPeer) _cancel(r Request) {
  49         active, ok := ws.activeRequests[r]
  50         if ok {
  51                 active.Cancel()
  52         }
  53 }
  54
  55 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  56         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  57 }
  58
  59 func (ws *webseedPeer) _request(r Request) {
  60         ws.requesterCond.Signal()
  61 }
  62
  63 func (ws *webseedPeer) doRequest(r Request) {
  64         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  65         ws.activeRequests[r] = webseedRequest
  66         func() {
  67                 ws.requesterCond.L.Unlock()
  68                 defer ws.requesterCond.L.Lock()
  69                 ws.requestResultHandler(r, webseedRequest)
  70         }()
  71         delete(ws.activeRequests, r)
  72 }
  73
  74 func (ws *webseedPeer) requester() {
  75         ws.requesterCond.L.Lock()
  76         defer ws.requesterCond.L.Unlock()
  77 start:
  78         for !ws.peer.closed.IsSet() {
  79                 for r := range ws.peer.requests {
  80                         if _, ok := ws.activeRequests[r]; ok {
  81                                 continue
  82                         }
  83                         ws.doRequest(r)
  84                         goto start
  85                 }
  86                 ws.requesterCond.Wait()
  87         }
  88 }
  89
  90 func (ws *webseedPeer) connectionFlags() string {
  91         return "WS"
  92 }
  93
  94 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
  95 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
  96 func (ws *webseedPeer) drop() {}
  97
  98 func (ws *webseedPeer) updateRequests() {
  99 }
 100
 101 func (ws *webseedPeer) onClose() {
 102         ws.peer.logger.Print("closing")
 103         for _, r := range ws.activeRequests {
 104                 r.Cancel()
 105         }
 106         ws.requesterCond.Broadcast()
 107 }
 108
 109 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 110         result := <-webseedRequest.Result
 111         ws.peer.t.cl.lock()
 112         defer ws.peer.t.cl.unlock()
 113         if result.Err != nil {
 114                 if !errors.Is(result.Err, context.Canceled) {
 115                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 116                 }
 117                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 118                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 119                 const closeOnAllErrors = false
 120                 if closeOnAllErrors ||
 121                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 122                         func() bool {
 123                                 var err webseed.ErrBadResponse
 124                                 if !errors.As(result.Err, &err) {
 125                                         return false
 126                                 }
 127                                 return err.Response.StatusCode == http.StatusNotFound
 128                         }() {
 129                         ws.peer.close()
 130                 } else {
 131                         ws.peer.remoteRejectedRequest(r)
 132                 }
 133         } else {
 134                 err := ws.peer.receiveChunk(&pp.Message{
 135                         Type:  pp.Piece,
 136                         Index: r.Index,
 137                         Begin: r.Begin,
 138                         Piece: result.Bytes,
 139                 })
 140                 if err != nil {
 141                         panic(err)
 142                 }
 143         }
 144 }