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         "strings"
  15
  16         "github.com/anacrolix/missinggo/httptoo"
  17         "github.com/anacrolix/torrent/bencode"
  18         "github.com/anacrolix/torrent/tracker/shared"
  19         "github.com/anacrolix/torrent/tracker/udp"
  20         "github.com/anacrolix/torrent/version"
  21 )
  22
  23 var vars = expvar.NewMap("tracker/http")
  24
  25 func setAnnounceParams(_url *url.URL, ar *AnnounceRequest, opts AnnounceOpt) {
  26         q := url.Values{}
  27
  28         q.Set("key", strconv.FormatInt(int64(ar.Key), 10))
  29         q.Set("info_hash", string(ar.InfoHash[:]))
  30         q.Set("peer_id", string(ar.PeerId[:]))
  31         // AFAICT, port is mandatory, and there's no implied port key.
  32         q.Set("port", fmt.Sprintf("%d", ar.Port))
  33         q.Set("uploaded", strconv.FormatInt(ar.Uploaded, 10))
  34         q.Set("downloaded", strconv.FormatInt(ar.Downloaded, 10))
  35
  36         // The AWS S3 tracker returns "400 Bad Request: left(-1) was not in the valid range 0 -
  37         // 9223372036854775807" if left is out of range, or "500 Internal Server Error: Internal Server
  38         // Error" if omitted entirely.
  39         left := ar.Left
  40         if left < 0 {
  41                 left = math.MaxInt64
  42         }
  43         q.Set("left", strconv.FormatInt(left, 10))
  44
  45         if ar.Event != shared.None {
  46                 q.Set("event", ar.Event.String())
  47         }
  48         // http://stackoverflow.com/questions/17418004/why-does-tracker-server-not-understand-my-request-bittorrent-protocol
  49         q.Set("compact", "1")
  50         // According to https://wiki.vuze.com/w/Message_Stream_Encryption. TODO:
  51         // Take EncryptionPolicy or something like it as a parameter.
  52         q.Set("supportcrypto", "1")
  53         doIp := func(versionKey string, ip net.IP) {
  54                 if ip == nil {
  55                         return
  56                 }
  57                 ipString := ip.String()
  58                 q.Set(versionKey, ipString)
  59                 // Let's try listing them. BEP 3 mentions having an "ip" param, and BEP 7 says we can list
  60                 // addresses for other address-families, although it's not encouraged.
  61                 q.Add("ip", ipString)
  62         }
  63         doIp("ipv4", opts.ClientIp4)
  64         doIp("ipv6", opts.ClientIp6)
  65         // We're operating purely on query-escaped strings, where + would have already been encoded to
  66         // %2B, and + has no other special meaning. See https://github.com/anacrolix/torrent/issues/534.
  67         qstr := strings.ReplaceAll(q.Encode(), "+", "%20")
  68
  69         // Some private trackers require the original query param to be in the first position.
  70         if _url.RawQuery != "" {
  71                 _url.RawQuery += "&" + qstr
  72         } else {
  73                 _url.RawQuery = qstr
  74         }
  75 }
  76
  77 type AnnounceOpt struct {
  78         UserAgent  string
  79         HostHeader string
  80         ClientIp4  net.IP
  81         ClientIp6  net.IP
  82 }
  83
  84 type AnnounceRequest = udp.AnnounceRequest
  85
  86 func (cl Client) Announce(ctx context.Context, ar AnnounceRequest, opt AnnounceOpt) (ret AnnounceResponse, err error) {
  87         _url := httptoo.CopyURL(cl.url_)
  88         setAnnounceParams(_url, &ar, opt)
  89         req, err := http.NewRequestWithContext(ctx, http.MethodGet, _url.String(), nil)
  90         userAgent := opt.UserAgent
  91         if userAgent == "" {
  92                 userAgent = version.DefaultHttpUserAgent
  93         }
  94         if userAgent != "" {
  95                 req.Header.Set("User-Agent", userAgent)
  96         }
  97         req.Host = opt.HostHeader
  98         resp, err := cl.hc.Do(req)
  99         if err != nil {
 100                 return
 101         }
 102         defer resp.Body.Close()
 103         var buf bytes.Buffer
 104         io.Copy(&buf, resp.Body)
 105         if resp.StatusCode != 200 {
 106                 err = fmt.Errorf("response from tracker: %s: %q", resp.Status, buf.Bytes())
 107                 return
 108         }
 109         var trackerResponse HttpResponse
 110         err = bencode.Unmarshal(buf.Bytes(), &trackerResponse)
 111         if _, ok := err.(bencode.ErrUnusedTrailingBytes); ok {
 112                 err = nil
 113         } else if err != nil {
 114                 err = fmt.Errorf("error decoding %q: %s", buf.Bytes(), err)
 115                 return
 116         }
 117         if trackerResponse.FailureReason != "" {
 118                 err = fmt.Errorf("tracker gave failure reason: %q", trackerResponse.FailureReason)
 119                 return
 120         }
 121         vars.Add("successful http announces", 1)
 122         ret.Interval = trackerResponse.Interval
 123         ret.Leechers = trackerResponse.Incomplete
 124         ret.Seeders = trackerResponse.Complete
 125         if len(trackerResponse.Peers) != 0 {
 126                 vars.Add("http responses with nonempty peers key", 1)
 127         }
 128         ret.Peers = trackerResponse.Peers
 129         if len(trackerResponse.Peers6) != 0 {
 130                 vars.Add("http responses with nonempty peers6 key", 1)
 131         }
 132         for _, na := range trackerResponse.Peers6 {
 133                 ret.Peers = append(ret.Peers, Peer{
 134                         IP:   na.IP,
 135                         Port: na.Port,
 136                 })
 137         }
 138         return
 139 }
 140
 141 type AnnounceResponse struct {
 142         Interval int32 // Minimum seconds the local peer should wait before next announce.
 143         Leechers int32
 144         Seeders  int32
 145         Peers    []Peer
 146 }