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) bool {
  49         active, ok := ws.activeRequests[r]
  50         if ok {
  51                 active.Cancel()
  52         }
  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.actualRequestState.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 }
 102
 103 func (ws *webseedPeer) onClose() {
 104         ws.peer.logger.Print("closing")
 105         for _, r := range ws.activeRequests {
 106                 r.Cancel()
 107         }
 108         ws.requesterCond.Broadcast()
 109 }
 110
 111 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 112         result := <-webseedRequest.Result
 113         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 114         // sure if we can divine which errors indicate cancellation on our end without hitting the
 115         // network though.
 116         ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 117         ws.peer.t.cl.lock()
 118         defer ws.peer.t.cl.unlock()
 119         if result.Err != nil {
 120                 if !errors.Is(result.Err, context.Canceled) {
 121                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 122                 }
 123                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 124                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 125                 const closeOnAllErrors = false
 126                 if closeOnAllErrors ||
 127                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 128                         func() bool {
 129                                 var err webseed.ErrBadResponse
 130                                 if !errors.As(result.Err, &err) {
 131                                         return false
 132                                 }
 133                                 return err.Response.StatusCode == http.StatusNotFound
 134                         }() {
 135                         ws.peer.close()
 136                 } else {
 137                         ws.peer.remoteRejectedRequest(r)
 138                 }
 139         } else {
 140                 err := ws.peer.receiveChunk(&pp.Message{
 141                         Type:  pp.Piece,
 142                         Index: r.Index,
 143                         Begin: r.Begin,
 144                         Piece: result.Bytes,
 145                 })
 146                 if err != nil {
 147                         panic(err)
 148                 }
 149         }
 150 }
 151
 152 func (me *webseedPeer) onNextRequestStateChanged() {
 153         me.peer.applyNextRequestState()
 154 }