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) connStatusString() string {
  28         return me.client.Url
  29 }
  30
  31 func (ws *webseedPeer) String() string {
  32         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  33 }
  34
  35 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  36         ws.client.FileIndex = segments.NewIndex(common.LengthIterFromUpvertedFiles(info.UpvertedFiles()))
  37         ws.client.Info = info
  38 }
  39
  40 func (ws *webseedPeer) writeInterested(interested bool) bool {
  41         return true
  42 }
  43
  44 func (ws *webseedPeer) _cancel(r RequestIndex) bool {
  45         active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]
  46         if ok {
  47                 active.Cancel()
  48                 if !ws.peer.deleteRequest(r) {
  49                         panic("cancelled webseed request should exist")
  50                 }
  51                 if ws.peer.actualRequestState.Requests.IsEmpty() {
  52                         ws.peer.updateRequests("webseedPeer._cancel")
  53                 }
  54         }
  55         return true
  56 }
  57
  58 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  59         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  60 }
  61
  62 func (ws *webseedPeer) _request(r Request) bool {
  63         ws.requesterCond.Signal()
  64         return true
  65 }
  66
  67 func (ws *webseedPeer) doRequest(r Request) {
  68         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  69         ws.activeRequests[r] = webseedRequest
  70         func() {
  71                 ws.requesterCond.L.Unlock()
  72                 defer ws.requesterCond.L.Lock()
  73                 ws.requestResultHandler(r, webseedRequest)
  74         }()
  75         delete(ws.activeRequests, r)
  76 }
  77
  78 func (ws *webseedPeer) requester() {
  79         ws.requesterCond.L.Lock()
  80         defer ws.requesterCond.L.Unlock()
  81 start:
  82         for !ws.peer.closed.IsSet() {
  83                 restart := false
  84                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  85                         r := ws.peer.t.requestIndexToRequest(x)
  86                         if _, ok := ws.activeRequests[r]; ok {
  87                                 return true
  88                         }
  89                         ws.doRequest(r)
  90                         restart = true
  91                         return false
  92                 })
  93                 if restart {
  94                         goto start
  95                 }
  96                 ws.requesterCond.Wait()
  97         }
  98 }
  99
 100 func (ws *webseedPeer) connectionFlags() string {
 101         return "WS"
 102 }
 103
 104 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 105 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 106 func (ws *webseedPeer) drop() {}
 107
 108 func (ws *webseedPeer) updateRequests(reason string) {
 109 }
 110
 111 func (ws *webseedPeer) onClose() {
 112         ws.peer.logger.Print("closing")
 113         for _, r := range ws.activeRequests {
 114                 r.Cancel()
 115         }
 116         ws.requesterCond.Broadcast()
 117 }
 118
 119 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 120         result := <-webseedRequest.Result
 121         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 122         // sure if we can divine which errors indicate cancellation on our end without hitting the
 123         // network though.
 124         ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 125         ws.peer.t.cl.lock()
 126         defer ws.peer.t.cl.unlock()
 127         if result.Err != nil {
 128                 if !errors.Is(result.Err, context.Canceled) {
 129                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 130                 }
 131                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 132                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 133                 const closeOnAllErrors = false
 134                 if closeOnAllErrors ||
 135                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 136                         func() bool {
 137                                 var err webseed.ErrBadResponse
 138                                 if !errors.As(result.Err, &err) {
 139                                         return false
 140                                 }
 141                                 return err.Response.StatusCode == http.StatusNotFound
 142                         }() {
 143                         ws.peer.close()
 144                 } else {
 145                         ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 146                 }
 147         } else {
 148                 err := ws.peer.receiveChunk(&pp.Message{
 149                         Type:  pp.Piece,
 150                         Index: r.Index,
 151                         Begin: r.Begin,
 152                         Piece: result.Bytes,
 153                 })
 154                 if err != nil {
 155                         panic(err)
 156                 }
 157         }
 158 }