useTorrentSources: fix http request resource leak (#562)

diff --git a/client.go b/client.go
index 710fe9376e1d1adbda5065efe4c9cb838a4414b2..7d0b1f3c1ec7f944e58898a38e5bd0cb99331284 100644 (file)
--- a/client.go
+++ b/client.go
@@ -1214,24 +1214,22 @@ func (t *Torrent) MergeSpec(spec *TorrentSpec) error {
 }
 
 func useTorrentSources(sources []string, t *Torrent) {
-       for _, s := range sources {
-               go func(s string) {
-                       err := useTorrentSource(s, t)
-                       if err != nil {
+       // TODO: bind context to the lifetime of *Torrent so that it's cancelled if the torrent closes
+       ctx := context.Background()
+       for i := 0; i < len(sources); i += 1 {
+               s := sources[i]
+               go func() {
+                       if err := useTorrentSource(ctx, s, t); err != nil {
                                t.logger.WithDefaultLevel(log.Warning).Printf("using torrent source %q: %v", s, err)
                        } else {
                                t.logger.Printf("successfully used source %q", s)
                        }
-               }(s)
+               }()
        }
 }
 
-func useTorrentSource(source string, t *Torrent) error {
-       req, err := http.NewRequest(http.MethodGet, source, nil)
-       if err != nil {
-               panic(err)
-       }
-       ctx, cancel := context.WithCancel(context.Background())
+func useTorrentSource(ctx context.Context, source string, t *Torrent) (err error) {
+       ctx, cancel := context.WithCancel(ctx)
        defer cancel()
        go func() {
                select {
@@ -1241,21 +1239,27 @@ func useTorrentSource(source string, t *Torrent) error {
                }
                cancel()
        }()
-       req = req.WithContext(ctx)
-       resp, err := http.DefaultClient.Do(req)
-       if err != nil {
-               return err
+       var req *http.Request
+       if req, err = http.NewRequestWithContext(ctx, http.MethodGet, source, nil); err != nil {
+               panic(err)
+       }
+       var resp *http.Response
+       if resp, err = http.DefaultClient.Do(req); err != nil {
+               return
        }
-       mi, err := metainfo.Load(resp.Body)
+       var mi metainfo.MetaInfo
+       err = bencode.NewDecoder(resp.Body).Decode(&mi)
+       resp.Body.Close()
        if err != nil {
                if ctx.Err() != nil {
                        return nil
                }
-               return err
+               return
        }
-       return t.MergeSpec(TorrentSpecFromMetaInfo(mi))
+       return t.MergeSpec(TorrentSpecFromMetaInfo(&mi))
 }
 
+
 func (cl *Client) dropTorrent(infoHash metainfo.Hash) (err error) {
        t, ok := cl.torrents[infoHash]
        if !ok {