sources.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "fmt"
   6         "net/http"
   7
   8         "github.com/anacrolix/log"
   9         "github.com/anacrolix/torrent/bencode"
  10         "github.com/anacrolix/torrent/metainfo"
  11 )
  12
  13 // Add HTTP endpoints that serve the metainfo. They will be used if the torrent info isn't obtained
  14 // yet. The Client HTTP client is used.
  15 func (t *Torrent) UseSources(sources []string) {
  16         select {
  17         case <-t.Closed():
  18                 return
  19         case <-t.GotInfo():
  20                 return
  21         default:
  22         }
  23         for _, s := range sources {
  24                 _, loaded := t.activeSources.LoadOrStore(s, struct{}{})
  25                 if loaded {
  26                         continue
  27                 }
  28                 s := s
  29                 go func() {
  30                         err := t.useActiveTorrentSource(s)
  31                         _, loaded := t.activeSources.LoadAndDelete(s)
  32                         if !loaded {
  33                                 panic(s)
  34                         }
  35                         level := log.Debug
  36                         if err != nil {
  37                                 level = log.Warning
  38                         }
  39                         t.logger.Levelf(level, "used torrent source %q [err=%v]", s, err)
  40                 }()
  41         }
  42 }
  43
  44 func (t *Torrent) useActiveTorrentSource(source string) error {
  45         ctx, cancel := context.WithCancel(context.Background())
  46         defer cancel()
  47         go func() {
  48                 select {
  49                 case <-t.GotInfo():
  50                 case <-t.Closed():
  51                 case <-ctx.Done():
  52                 }
  53                 cancel()
  54         }()
  55         mi, err := getTorrentSource(ctx, source, t.cl.httpClient)
  56         if err != nil {
  57                 return err
  58         }
  59         return t.MergeSpec(TorrentSpecFromMetaInfo(&mi))
  60 }
  61
  62 func getTorrentSource(ctx context.Context, source string, hc *http.Client) (mi metainfo.MetaInfo, err error) {
  63         var req *http.Request
  64         if req, err = http.NewRequestWithContext(ctx, http.MethodGet, source, nil); err != nil {
  65                 return
  66         }
  67         var resp *http.Response
  68         if resp, err = hc.Do(req); err != nil {
  69                 return
  70         }
  71         defer resp.Body.Close()
  72         if resp.StatusCode != http.StatusOK {
  73                 err = fmt.Errorf("unexpected response status code: %v", resp.StatusCode)
  74                 return
  75         }
  76         err = bencode.NewDecoder(resp.Body).Decode(&mi)
  77         return
  78 }