sources.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "errors"
   6         "fmt"
   7         "net/http"
   8
   9         "github.com/anacrolix/log"
  10
  11         "github.com/anacrolix/torrent/bencode"
  12         "github.com/anacrolix/torrent/metainfo"
  13 )
  14
  15 // Add HTTP endpoints that serve the metainfo. They will be used if the torrent info isn't obtained
  16 // yet. The Client HTTP client is used.
  17 func (t *Torrent) UseSources(sources []string) {
  18         select {
  19         case <-t.Closed():
  20                 return
  21         case <-t.GotInfo():
  22                 return
  23         default:
  24         }
  25         for _, s := range sources {
  26                 _, loaded := t.activeSources.LoadOrStore(s, struct{}{})
  27                 if loaded {
  28                         continue
  29                 }
  30                 s := s
  31                 go func() {
  32                         err := t.useActiveTorrentSource(s)
  33                         _, loaded := t.activeSources.LoadAndDelete(s)
  34                         if !loaded {
  35                                 panic(s)
  36                         }
  37                         level := log.Debug
  38                         if err != nil && !errors.Is(err, context.Canceled) {
  39                                 level = log.Warning
  40                         }
  41                         t.logger.Levelf(level, "used torrent source %q [err=%v]", s, err)
  42                 }()
  43         }
  44 }
  45
  46 func (t *Torrent) useActiveTorrentSource(source string) error {
  47         ctx, cancel := context.WithCancel(context.Background())
  48         defer cancel()
  49         go func() {
  50                 select {
  51                 case <-t.GotInfo():
  52                 case <-t.Closed():
  53                 case <-ctx.Done():
  54                 }
  55                 cancel()
  56         }()
  57         mi, err := getTorrentSource(ctx, source, t.cl.httpClient)
  58         if err != nil {
  59                 return err
  60         }
  61         return t.MergeSpec(TorrentSpecFromMetaInfo(&mi))
  62 }
  63
  64 func getTorrentSource(ctx context.Context, source string, hc *http.Client) (mi metainfo.MetaInfo, err error) {
  65         var req *http.Request
  66         if req, err = http.NewRequestWithContext(ctx, http.MethodGet, source, nil); err != nil {
  67                 return
  68         }
  69         var resp *http.Response
  70         if resp, err = hc.Do(req); err != nil {
  71                 return
  72         }
  73         defer resp.Body.Close()
  74         if resp.StatusCode != http.StatusOK {
  75                 err = fmt.Errorf("unexpected response status code: %v", resp.StatusCode)
  76                 return
  77         }
  78         err = bencode.NewDecoder(resp.Body).Decode(&mi)
  79         return
  80 }