tracker/http/server/server.go

   1 package httpTrackerServer
   2
   3 import (
   4         "fmt"
   5         "net"
   6         "net/http"
   7         "net/netip"
   8         "net/url"
   9         "strconv"
  10
  11         "github.com/anacrolix/dht/v2/krpc"
  12         "github.com/anacrolix/generics"
  13         "github.com/anacrolix/log"
  14
  15         "github.com/anacrolix/torrent/bencode"
  16         "github.com/anacrolix/torrent/tracker"
  17         httpTracker "github.com/anacrolix/torrent/tracker/http"
  18 )
  19
  20 type Handler struct {
  21         Announce *tracker.AnnounceHandler
  22         // Called to derive an announcer's IP if non-nil. If not specified, the Request.RemoteAddr is
  23         // used. Necessary for instances running behind reverse proxies for example.
  24         RequestHost func(r *http.Request) (netip.Addr, error)
  25 }
  26
  27 func unmarshalQueryKeyToArray(w http.ResponseWriter, key string, query url.Values) (ret [20]byte, ok bool) {
  28         str := query.Get(key)
  29         if len(str) != len(ret) {
  30                 http.Error(w, fmt.Sprintf("%v has wrong length", key), http.StatusBadRequest)
  31                 return
  32         }
  33         copy(ret[:], str)
  34         ok = true
  35         return
  36 }
  37
  38 // Returns false if there was an error and it was served.
  39 func (me Handler) requestHostAddr(r *http.Request) (_ netip.Addr, err error) {
  40         if me.RequestHost != nil {
  41                 return me.RequestHost(r)
  42         }
  43         host, _, err := net.SplitHostPort(r.RemoteAddr)
  44         if err != nil {
  45                 return
  46         }
  47         return netip.ParseAddr(host)
  48 }
  49
  50 var requestHeadersLogger = log.Default.WithNames("request", "headers")
  51
  52 func (me Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  53         vs := r.URL.Query()
  54         var event tracker.AnnounceEvent
  55         err := event.UnmarshalText([]byte(vs.Get("event")))
  56         if err != nil {
  57                 http.Error(w, err.Error(), http.StatusBadRequest)
  58                 return
  59         }
  60         infoHash, ok := unmarshalQueryKeyToArray(w, "info_hash", vs)
  61         if !ok {
  62                 return
  63         }
  64         peerId, ok := unmarshalQueryKeyToArray(w, "peer_id", vs)
  65         if !ok {
  66                 return
  67         }
  68         requestHeadersLogger.Levelf(log.Debug, "request RemoteAddr=%q, header=%q", r.RemoteAddr, r.Header)
  69         addr, err := me.requestHostAddr(r)
  70         if err != nil {
  71                 log.Printf("error getting requester IP: %v", err)
  72                 http.Error(w, "error determining your IP", http.StatusBadGateway)
  73                 return
  74         }
  75         portU64, err := strconv.ParseUint(vs.Get("port"), 0, 16)
  76         addrPort := netip.AddrPortFrom(addr, uint16(portU64))
  77         res := me.Announce.Serve(r.Context(), tracker.AnnounceRequest{
  78                 InfoHash: infoHash,
  79                 PeerId:   peerId,
  80                 Event:    event,
  81                 Port:     addrPort.Port(),
  82                 NumWant:  -1,
  83         }, addrPort, tracker.GetPeersOpts{MaxCount: generics.Some[uint](200)})
  84         err = res.Err
  85         if err != nil {
  86                 log.Printf("error serving announce: %v", err)
  87                 http.Error(w, "error handling announce", http.StatusInternalServerError)
  88                 return
  89         }
  90         var resp httpTracker.HttpResponse
  91         resp.Interval = res.Interval.UnwrapOr(5 * 60)
  92         resp.Peers.Compact = true
  93         for _, peer := range res.Peers {
  94                 if peer.Addr().Is4() {
  95                         resp.Peers.List = append(resp.Peers.List, tracker.Peer{
  96                                 IP:   peer.Addr().AsSlice(),
  97                                 Port: int(peer.Port()),
  98                         })
  99                 } else if peer.Addr().Is6() {
 100                         resp.Peers6 = append(resp.Peers6, krpc.NodeAddr{
 101                                 IP:   peer.Addr().AsSlice(),
 102                                 Port: int(peer.Port()),
 103                         })
 104                 }
 105         }
 106         err = bencode.NewEncoder(w).Encode(resp)
 107         if err != nil {
 108                 log.Printf("error encoding and writing response body: %v", err)
 109         }
 110 }