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/log"
  12         "github.com/anacrolix/torrent/common"
  13         "github.com/anacrolix/torrent/metainfo"
  14         pp "github.com/anacrolix/torrent/peer_protocol"
  15         "github.com/anacrolix/torrent/segments"
  16         "github.com/anacrolix/torrent/webseed"
  17 )
  18
  19 type webseedPeer struct {
  20         client         webseed.Client
  21         activeRequests map[Request]webseed.Request
  22         requesterCond  sync.Cond
  23         peer           Peer
  24 }
  25
  26 var _ peerImpl = (*webseedPeer)(nil)
  27
  28 func (me *webseedPeer) connStatusString() string {
  29         return me.client.Url
  30 }
  31
  32 func (ws *webseedPeer) String() string {
  33         return fmt.Sprintf("webseed peer for %q", ws.client.Url)
  34 }
  35
  36 func (ws *webseedPeer) onGotInfo(info *metainfo.Info) {
  37         ws.client.FileIndex = segments.NewIndex(common.LengthIterFromUpvertedFiles(info.UpvertedFiles()))
  38         ws.client.Info = info
  39 }
  40
  41 func (ws *webseedPeer) writeInterested(interested bool) bool {
  42         return true
  43 }
  44
  45 func (ws *webseedPeer) _cancel(r RequestIndex) bool {
  46         active, ok := ws.activeRequests[ws.peer.t.requestIndexToRequest(r)]
  47         if ok {
  48                 active.Cancel()
  49                 if !ws.peer.deleteRequest(r) {
  50                         panic("cancelled webseed request should exist")
  51                 }
  52                 if ws.peer.actualRequestState.Requests.IsEmpty() {
  53                         ws.peer.updateRequests("webseedPeer._cancel")
  54                 }
  55         }
  56         return true
  57 }
  58
  59 func (ws *webseedPeer) intoSpec(r Request) webseed.RequestSpec {
  60         return webseed.RequestSpec{ws.peer.t.requestOffset(r), int64(r.Length)}
  61 }
  62
  63 func (ws *webseedPeer) _request(r Request) bool {
  64         ws.requesterCond.Signal()
  65         return true
  66 }
  67
  68 func (ws *webseedPeer) doRequest(r Request) {
  69         webseedRequest := ws.client.NewRequest(ws.intoSpec(r))
  70         ws.activeRequests[r] = webseedRequest
  71         func() {
  72                 ws.requesterCond.L.Unlock()
  73                 defer ws.requesterCond.L.Lock()
  74                 ws.requestResultHandler(r, webseedRequest)
  75         }()
  76         delete(ws.activeRequests, r)
  77 }
  78
  79 func (ws *webseedPeer) requester() {
  80         ws.requesterCond.L.Lock()
  81         defer ws.requesterCond.L.Unlock()
  82 start:
  83         for !ws.peer.closed.IsSet() {
  84                 restart := false
  85                 ws.peer.actualRequestState.Requests.Iterate(func(x uint32) bool {
  86                         r := ws.peer.t.requestIndexToRequest(x)
  87                         if _, ok := ws.activeRequests[r]; ok {
  88                                 return true
  89                         }
  90                         ws.doRequest(r)
  91                         restart = true
  92                         return false
  93                 })
  94                 if restart {
  95                         goto start
  96                 }
  97                 ws.requesterCond.Wait()
  98         }
  99 }
 100
 101 func (ws *webseedPeer) connectionFlags() string {
 102         return "WS"
 103 }
 104
 105 // TODO: This is called when banning peers. Perhaps we want to be able to ban webseeds too. We could
 106 // return bool if this is even possible, and if it isn't, skip to the next drop candidate.
 107 func (ws *webseedPeer) drop() {}
 108
 109 func (ws *webseedPeer) handleUpdateRequests() {
 110         ws.peer.maybeUpdateActualRequestState()
 111 }
 112
 113 func (ws *webseedPeer) onClose() {
 114         ws.peer.logger.WithLevel(log.Debug).Print("closing")
 115         for _, r := range ws.activeRequests {
 116                 r.Cancel()
 117         }
 118         ws.requesterCond.Broadcast()
 119 }
 120
 121 func (ws *webseedPeer) requestResultHandler(r Request, webseedRequest webseed.Request) {
 122         result := <-webseedRequest.Result
 123         // We do this here rather than inside receiveChunk, since we want to count errors too. I'm not
 124         // sure if we can divine which errors indicate cancellation on our end without hitting the
 125         // network though.
 126         ws.peer.doChunkReadStats(int64(len(result.Bytes)))
 127         ws.peer.t.cl.lock()
 128         defer ws.peer.t.cl.unlock()
 129         if result.Err != nil {
 130                 if !errors.Is(result.Err, context.Canceled) {
 131                         ws.peer.logger.Printf("Request %v rejected: %v", r, result.Err)
 132                 }
 133                 // We need to filter out temporary errors, but this is a nightmare in Go. Currently a bad
 134                 // webseed URL can starve out the good ones due to the chunk selection algorithm.
 135                 const closeOnAllErrors = false
 136                 if closeOnAllErrors ||
 137                         strings.Contains(result.Err.Error(), "unsupported protocol scheme") ||
 138                         func() bool {
 139                                 var err webseed.ErrBadResponse
 140                                 if !errors.As(result.Err, &err) {
 141                                         return false
 142                                 }
 143                                 return err.Response.StatusCode == http.StatusNotFound
 144                         }() {
 145                         ws.peer.close()
 146                 } else {
 147                         ws.peer.remoteRejectedRequest(ws.peer.t.requestIndexFromRequest(r))
 148                 }
 149         } else {
 150                 err := ws.peer.receiveChunk(&pp.Message{
 151                         Type:  pp.Piece,
 152                         Index: r.Index,
 153                         Begin: r.Begin,
 154                         Piece: result.Bytes,
 155                 })
 156                 if err != nil {
 157                         panic(err)
 158                 }
 159         }
 160 }