tracker/http/http.go

   1 package http
   2
   3 import (
   4         "bytes"
   5         "context"
   6         "expvar"
   7         "fmt"
   8         "io"
   9         "math"
  10         "net"
  11         "net/http"
  12         "net/url"
  13         "strconv"
  14
  15         "github.com/anacrolix/missinggo/httptoo"
  16         "github.com/anacrolix/torrent/bencode"
  17         "github.com/anacrolix/torrent/tracker/shared"
  18         "github.com/anacrolix/torrent/tracker/udp"
  19 )
  20
  21 var vars = expvar.NewMap("tracker/http")
  22
  23 func setAnnounceParams(_url *url.URL, ar *AnnounceRequest, opts AnnounceOpt) {
  24         q := _url.Query()
  25
  26         q.Set("key", strconv.FormatInt(int64(ar.Key), 10))
  27         q.Set("info_hash", string(ar.InfoHash[:]))
  28         q.Set("peer_id", string(ar.PeerId[:]))
  29         // AFAICT, port is mandatory, and there's no implied port key.
  30         q.Set("port", fmt.Sprintf("%d", ar.Port))
  31         q.Set("uploaded", strconv.FormatInt(ar.Uploaded, 10))
  32         q.Set("downloaded", strconv.FormatInt(ar.Downloaded, 10))
  33
  34         // The AWS S3 tracker returns "400 Bad Request: left(-1) was not in the valid range 0 -
  35         // 9223372036854775807" if left is out of range, or "500 Internal Server Error: Internal Server
  36         // Error" if omitted entirely.
  37         left := ar.Left
  38         if left < 0 {
  39                 left = math.MaxInt64
  40         }
  41         q.Set("left", strconv.FormatInt(left, 10))
  42
  43         if ar.Event != shared.None {
  44                 q.Set("event", ar.Event.String())
  45         }
  46         // http://stackoverflow.com/questions/17418004/why-does-tracker-server-not-understand-my-request-bittorrent-protocol
  47         q.Set("compact", "1")
  48         // According to https://wiki.vuze.com/w/Message_Stream_Encryption. TODO:
  49         // Take EncryptionPolicy or something like it as a parameter.
  50         q.Set("supportcrypto", "1")
  51         doIp := func(versionKey string, ip net.IP) {
  52                 if ip == nil {
  53                         return
  54                 }
  55                 ipString := ip.String()
  56                 q.Set(versionKey, ipString)
  57                 // Let's try listing them. BEP 3 mentions having an "ip" param, and BEP 7 says we can list
  58                 // addresses for other address-families, although it's not encouraged.
  59                 q.Add("ip", ipString)
  60         }
  61         doIp("ipv4", opts.ClientIp4)
  62         doIp("ipv6", opts.ClientIp6)
  63         _url.RawQuery = q.Encode()
  64 }
  65
  66 type AnnounceOpt struct {
  67         UserAgent  string
  68         HostHeader string
  69         ClientIp4  net.IP
  70         ClientIp6  net.IP
  71 }
  72
  73 type AnnounceRequest = udp.AnnounceRequest
  74
  75 func (cl Client) Announce(ctx context.Context, ar AnnounceRequest, opt AnnounceOpt) (ret AnnounceResponse, err error) {
  76         _url := httptoo.CopyURL(cl.url_)
  77         setAnnounceParams(_url, &ar, opt)
  78         req, err := http.NewRequestWithContext(ctx, http.MethodGet, _url.String(), nil)
  79         req.Header.Set("User-Agent", opt.UserAgent)
  80         req.Host = opt.HostHeader
  81         resp, err := cl.hc.Do(req)
  82         if err != nil {
  83                 return
  84         }
  85         defer resp.Body.Close()
  86         var buf bytes.Buffer
  87         io.Copy(&buf, resp.Body)
  88         if resp.StatusCode != 200 {
  89                 err = fmt.Errorf("response from tracker: %s: %s", resp.Status, buf.String())
  90                 return
  91         }
  92         var trackerResponse HttpResponse
  93         err = bencode.Unmarshal(buf.Bytes(), &trackerResponse)
  94         if _, ok := err.(bencode.ErrUnusedTrailingBytes); ok {
  95                 err = nil
  96         } else if err != nil {
  97                 err = fmt.Errorf("error decoding %q: %s", buf.Bytes(), err)
  98                 return
  99         }
 100         if trackerResponse.FailureReason != "" {
 101                 err = fmt.Errorf("tracker gave failure reason: %q", trackerResponse.FailureReason)
 102                 return
 103         }
 104         vars.Add("successful http announces", 1)
 105         ret.Interval = trackerResponse.Interval
 106         ret.Leechers = trackerResponse.Incomplete
 107         ret.Seeders = trackerResponse.Complete
 108         if len(trackerResponse.Peers) != 0 {
 109                 vars.Add("http responses with nonempty peers key", 1)
 110         }
 111         ret.Peers = trackerResponse.Peers
 112         if len(trackerResponse.Peers6) != 0 {
 113                 vars.Add("http responses with nonempty peers6 key", 1)
 114         }
 115         for _, na := range trackerResponse.Peers6 {
 116                 ret.Peers = append(ret.Peers, Peer{
 117                         IP:   na.IP,
 118                         Port: na.Port,
 119                 })
 120         }
 121         return
 122 }
 123
 124 type AnnounceResponse struct {
 125         Interval int32 // Minimum seconds the local peer should wait before next announce.
 126         Leechers int32
 127         Seeders  int32
 128         Peers    []Peer
 129 }