12 // Magnet link components.
20 const xtPrefix = "urn:btih:"
22 func (m Magnet) String() string {
24 vs := make(url.Values, len(m.Params)+len(m.Trackers)+2)
25 for k, v := range m.Params {
26 vs[k] = append([]string(nil), v...)
29 vs.Add("xt", xtPrefix+m.InfoHash.HexString())
30 for _, tr := range m.Trackers {
33 if m.DisplayName != "" {
34 vs.Add("dn", m.DisplayName)
39 RawQuery: vs.Encode(),
43 // ParseMagnetURI parses Magnet-formatted URIs into a Magnet instance
44 func ParseMagnetURI(uri string) (m Magnet, err error) {
45 u, err := url.Parse(uri)
47 err = fmt.Errorf("error parsing uri: %w", err)
50 if u.Scheme != "magnet" {
51 err = fmt.Errorf("unexpected scheme %q", u.Scheme)
56 m.InfoHash, err = parseInfohash(q.Get("xt"))
58 err = fmt.Errorf("error parsing infohash %q: %w", xt, err)
62 m.DisplayName = q.Get("dn")
73 func parseInfohash(xt string) (ih Hash, err error) {
74 if !strings.HasPrefix(xt, xtPrefix) {
75 err = errors.New("bad xt parameter prefix")
78 encoded := xt[len(xtPrefix):]
79 decode := func() func(dst, src []byte) (int, error) {
84 return base32.StdEncoding.Decode
89 err = fmt.Errorf("unhandled xt parameter encoding (encoded length %d)", len(encoded))
92 n, err := decode(ih[:], []byte(encoded))
94 err = fmt.Errorf("error decoding xt: %w", err)
103 func dropFirst(vs url.Values, key string) {