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) _postCancel(r Request) {
  41         ws.cancel(r)
  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                 return false
  52         }
  53         active.Cancel()
  54         return true
  55 }
  56
  57 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  58         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  59 }
  60
  61 func (ws *webseedPeer) request(r Request) bool {
  62         ws.requesterCond.Signal()
  63         return true
  64 }
  65
  66 func (ws *webseedPeer) doRequest(r Request) {
  67         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  68         ws.activeRequests[r] = webseedRequest
  69         func() {
  70                 ws.requesterCond.L.Unlock()
  71                 defer ws.requesterCond.L.Lock()
  72                 ws.requestResultHandler(r, webseedRequest)
  73         }()
  74         delete(ws.activeRequests, r)
  75 }
  76
  77 func (ws *webseedPeer) requester() {
  78         ws.requesterCond.L.Lock()
  79         defer ws.requesterCond.L.Unlock()
  80 start:
  81         for !ws.peer.closed.IsSet() {
  82                 for r := range ws.peer.requests {
  83                         if _, ok := ws.activeRequests[r]; ok {
  84                                 continue
  85                         }
  86                         ws.doRequest(r)
  87                         goto start
  88                 }
  89                 ws.requesterCond.Wait()
  90         }
  91 }
  92
  93 func (ws *webseedPeer) connectionFlags() string {
  94         return "WS"
  95 }
  96
  97 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
  98 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
  99 func (ws *webseedPeer) drop() {}
 100
 101 func (ws *webseedPeer) updateRequests() {
 102         ws.peer.doRequestState()
 103 }
 104
 105 func (ws *webseedPeer) onClose() {
 106         ws.peer.logger.Print("closing")
 107         for _, r := range ws.activeRequests {
 108                 r.Cancel()
 109         }
 110         ws.requesterCond.Broadcast()
 111 }
 112
 113 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 114         result := <-webseedRequest.Result
 115         ws.peer.t.cl.lock()
 116         defer ws.peer.t.cl.unlock()
 117         if result.Err != nil {
 118                 if !errors.Is(result.Err, context.Canceled) {
 119                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 120                 }
 121                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 122                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 123                 const closeOnAllErrors = false
 124                 if closeOnAllErrors ||
 125                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 126                         func() bool {
 127                                 var err webseed.ErrBadResponse
 128                                 if !errors.As(result.Err, &err) {
 129                                         return false
 130                                 }
 131                                 return err.Response.StatusCode == http.StatusNotFound
 132                         }() {
 133                         ws.peer.close()
 134                 } else {
 135                         ws.peer.remoteRejectedRequest(r)
 136                 }
 137         } else {
 138                 err := ws.peer.receiveChunk(&pp.Message{
 139                         Type:  pp.Piece,
 140                         Index: r.Index,
 141                         Begin: r.Begin,
 142                         Piece: result.Bytes,
 143                 })
 144                 if err != nil {
 145                         panic(err)
 146                 }
 147         }
 148 }