12 // Magnet link components.
14 InfoHash Hash // Expected in this implementation
15 Trackers []string // "tr" values
16 DisplayName string // "dn" value, if not empty
17 Params url.Values // All other values, such as "x.pe", "as", "xs" etc.
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 for _, tr := range m.Trackers {
32 if m.DisplayName != "" {
33 vs.Add("dn", m.DisplayName)
36 // Transmission and Deluge both expect "urn:btih:" to be unescaped. Deluge wants it to be at the
37 // start of the magnet link. The InfoHash field is expected to be BitTorrent in this
41 RawQuery: "xt=" + xtPrefix + m.InfoHash.HexString(),
44 u.RawQuery += "&" + vs.Encode()
49 // ParseMagnetUri parses Magnet-formatted URIs into a Magnet instance
50 func ParseMagnetUri(uri string) (m Magnet, err error) {
51 u, err := url.Parse(uri)
53 err = fmt.Errorf("error parsing uri: %w", err)
56 if u.Scheme != "magnet" {
57 err = fmt.Errorf("unexpected scheme %q", u.Scheme)
62 m.InfoHash, err = parseInfohash(q.Get("xt"))
64 err = fmt.Errorf("error parsing infohash %q: %w", xt, err)
68 m.DisplayName = q.Get("dn")
79 func parseInfohash(xt string) (ih Hash, err error) {
80 if !strings.HasPrefix(xt, xtPrefix) {
81 err = errors.New("bad xt parameter prefix")
84 encoded := xt[len(xtPrefix):]
85 decode := func() func(dst, src []byte) (int, error) {
90 return base32.StdEncoding.Decode
95 err = fmt.Errorf("unhandled xt parameter encoding (encoded length %d)", len(encoded))
98 n, err := decode(ih[:], []byte(encoded))
100 err = fmt.Errorf("error decoding xt: %w", err)
109 func dropFirst(vs url.Values, key string) {