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 RequestIndex) bool {
  49         active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]
  50         if ok {
  51                 active.Cancel()
  52                 if !ws.peer.deleteRequest(r) {
  53                         panic("cancelled webseed request should exist")
  54                 }
  55                 if ws.peer.actualRequestState.Requests.GetCardinality() == 0 {
  56                         ws.peer.updateRequests("webseedPeer._cancel")
  57                 }
  58         }
  59         return true
  60 }
  61
  62 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  63         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  64 }
  65
  66 func (ws *webseedPeer) _request(r Request) bool {
  67         ws.requesterCond.Signal()
  68         return true
  69 }
  70
  71 func (ws *webseedPeer) doRequest(r Request) {
  72         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  73         ws.activeRequests[r] = webseedRequest
  74         func() {
  75                 ws.requesterCond.L.Unlock()
  76                 defer ws.requesterCond.L.Lock()
  77                 ws.requestResultHandler(r, webseedRequest)
  78         }()
  79         delete(ws.activeRequests, r)
  80 }
  81
  82 func (ws *webseedPeer) requester() {
  83         ws.requesterCond.L.Lock()
  84         defer ws.requesterCond.L.Unlock()
  85 start:
  86         for !ws.peer.closed.IsSet() {
  87                 restart := false
  88                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  89                         r := ws.peer.t.requestIndexToRequest(x)
  90                         if _, ok := ws.activeRequests[r]; ok {
  91                                 return true
  92                         }
  93                         ws.doRequest(r)
  94                         restart = true
  95                         return false
  96                 })
  97                 if restart {
  98                         goto start
  99                 }
 100                 ws.requesterCond.Wait()
 101         }
 102 }
 103
 104 func (ws *webseedPeer) connectionFlags() string {
 105         return "WS"
 106 }
 107
 108 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 109 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 110 func (ws *webseedPeer) drop() {}
 111
 112 func (ws *webseedPeer) updateRequests(reason string) {
 113 }
 114
 115 func (ws *webseedPeer) onClose() {
 116         ws.peer.logger.Print("closing")
 117         for _, r := range ws.activeRequests {
 118                 r.Cancel()
 119         }
 120         ws.requesterCond.Broadcast()
 121 }
 122
 123 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 124         result := <-webseedRequest.Result
 125         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 126         // sure if we can divine which errors indicate cancellation on our end without hitting the
 127         // network though.
 128         ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 129         ws.peer.t.cl.lock()
 130         defer ws.peer.t.cl.unlock()
 131         if result.Err != nil {
 132                 if !errors.Is(result.Err, context.Canceled) {
 133                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 134                 }
 135                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 136                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 137                 const closeOnAllErrors = false
 138                 if closeOnAllErrors ||
 139                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 140                         func() bool {
 141                                 var err webseed.ErrBadResponse
 142                                 if !errors.As(result.Err, &err) {
 143                                         return false
 144                                 }
 145                                 return err.Response.StatusCode == http.StatusNotFound
 146                         }() {
 147                         ws.peer.close()
 148                 } else {
 149                         ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 150                 }
 151         } else {
 152                 err := ws.peer.receiveChunk(&pp.Message{
 153                         Type:  pp.Piece,
 154                         Index: r.Index,
 155                         Begin: r.Begin,
 156                         Piece: result.Bytes,
 157                 })
 158                 if err != nil {
 159                         panic(err)
 160                 }
 161         }
 162 }
 163
 164 func (me *webseedPeer) onNextRequestStateChanged() {
 165         me.peer.applyNextRequestState()
 166 }