sources.go

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