webseed-peer.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "errors"
   6         "fmt"
   7         "strings"
   8         "sync"
   9
  10         "github.com/anacrolix/torrent/common"
  11         "github.com/anacrolix/torrent/metainfo"
  12         pp "github.com/anacrolix/torrent/peer_protocol"
  13         "github.com/anacrolix/torrent/segments"
  14         "github.com/anacrolix/torrent/webseed"
  15 )
  16
  17 type webseedPeer struct {
  18         client         webseed.Client
  19         activeRequests map[Request]webseed.Request
  20         requesterCond  sync.Cond
  21         peer           Peer
  22 }
  23
  24 var _ peerImpl = (*webseedPeer)(nil)
  25
  26 func (me *webseedPeer) connStatusString() string {
  27         return me.client.Url
  28 }
  29
  30 func (ws *webseedPeer) String() string {
  31         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  32 }
  33
  34 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  35         ws.client.FileIndex = segments.NewIndex(common.LengthIterFromUpvertedFiles(info.UpvertedFiles()))
  36         ws.client.Info = info
  37 }
  38
  39 func (ws *webseedPeer) _postCancel(r Request) {
  40         ws.cancel(r)
  41 }
  42
  43 func (ws *webseedPeer) writeInterested(interested bool) bool {
  44         return true
  45 }
  46
  47 func (ws *webseedPeer) cancel(r Request) bool {
  48         active, ok := ws.activeRequests[r]
  49         if !ok {
  50                 return false
  51         }
  52         active.Cancel()
  53         return true
  54 }
  55
  56 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  57         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  58 }
  59
  60 func (ws *webseedPeer) request(r Request) bool {
  61         ws.requesterCond.Signal()
  62         return true
  63 }
  64
  65 func (ws *webseedPeer) doRequest(r Request) {
  66         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  67         ws.activeRequests[r] = webseedRequest
  68         func() {
  69                 ws.requesterCond.L.Unlock()
  70                 defer ws.requesterCond.L.Lock()
  71                 ws.requestResultHandler(r, webseedRequest)
  72         }()
  73         delete(ws.activeRequests, r)
  74 }
  75
  76 func (ws *webseedPeer) requester() {
  77         ws.requesterCond.L.Lock()
  78         defer ws.requesterCond.L.Unlock()
  79 start:
  80         for !ws.peer.closed.IsSet() {
  81                 for r := range ws.peer.requests {
  82                         if _, ok := ws.activeRequests[r]; ok {
  83                                 continue
  84                         }
  85                         ws.doRequest(r)
  86                         goto start
  87                 }
  88                 ws.requesterCond.Wait()
  89         }
  90 }
  91
  92 func (ws *webseedPeer) connectionFlags() string {
  93         return "WS"
  94 }
  95
  96 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
  97 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
  98 func (ws *webseedPeer) drop() {}
  99
 100 func (ws *webseedPeer) updateRequests() {
 101         ws.peer.doRequestState()
 102 }
 103
 104 func (ws *webseedPeer) onClose() {
 105         ws.peer.logger.Print("closing")
 106         for _, r := range ws.activeRequests {
 107                 r.Cancel()
 108         }
 109         ws.requesterCond.Broadcast()
 110 }
 111
 112 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 113         result := <-webseedRequest.Result
 114         ws.peer.t.cl.lock()
 115         defer ws.peer.t.cl.unlock()
 116         if result.Err != nil {
 117                 if !errors.Is(result.Err, context.Canceled) {
 118                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 119                 }
 120                 // Always close for now. We need to filter out temporary errors, but this is a nightmare in
 121                 // Go. Currently a bad webseed URL can starve out the good ones due to the chunk selection
 122                 // algorithm.
 123                 const closeOnAllErrors = false
 124                 if closeOnAllErrors || strings.Contains(result.Err.Error(), "unsupported protocol scheme") {
 125                         ws.peer.close()
 126                 } else {
 127                         ws.peer.remoteRejectedRequest(r)
 128                 }
 129         } else {
 130                 err := ws.peer.receiveChunk(&pp.Message{
 131                         Type:  pp.Piece,
 132                         Index: r.Index,
 133                         Begin: r.Begin,
 134                         Piece: result.Bytes,
 135                 })
 136                 if err != nil {
 137                         panic(err)
 138                 }
 139         }
 140 }