From 9869f8f5a9220d71d56e9dce7dc1c9ddc8dbb884 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 26 Mar 2015 17:20:31 +1100
Subject: [PATCH] Almost completed http tracker support

---
 tracker/http/httptracker.go | 112 ++++++++++++++++++++++++++++++++++++
 tracker/tracker.go          |   5 ++
 2 files changed, 117 insertions(+)
 create mode 100644 tracker/http/httptracker.go

diff --git a/tracker/http/httptracker.go b/tracker/http/httptracker.go
new file mode 100644
index 00000000..432d00cf
--- /dev/null
+++ b/tracker/http/httptracker.go
@@ -0,0 +1,112 @@
+package http
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+
+	"github.com/anacrolix/torrent/util"
+
+	"github.com/anacrolix/libtorgo/bencode"
+
+	"github.com/anacrolix/torrent/tracker"
+)
+
+func init() {
+	tracker.RegisterClientScheme("http", NewClient)
+}
+
+type client struct {
+	url url.URL
+}
+
+func NewClient(url *url.URL) tracker.Client {
+	return &client{
+		url: *url,
+	}
+}
+
+type response struct {
+	FailureReason string      `bencode:"failure reason"`
+	Interval      int32       `bencode:"interval"`
+	TrackerId     string      `bencode:"tracker id"`
+	Complete      int32       `bencode:"complete"`
+	Incomplete    int32       `bencode:"incomplete"`
+	Peers         interface{} `bencode:"peers"`
+}
+
+func (r *response) UnmarshalPeers() (ret []tracker.Peer, err error) {
+	s, ok := r.Peers.(string)
+	if !ok {
+		err = fmt.Errorf("unsupported peers value type: %T", r.Peers)
+		return
+	}
+	cp := make(util.CompactPeers, 0, len(s)/6)
+	err = cp.UnmarshalBinary([]byte(s))
+	if err != nil {
+		return
+	}
+	ret = make([]tracker.Peer, 0, len(cp))
+	for _, p := range cp {
+		ret = append(ret, tracker.Peer{net.IP(p.IP[:]), int(p.Port)})
+	}
+	return
+}
+
+func (me *client) Announce(ar *tracker.AnnounceRequest) (ret tracker.AnnounceResponse, err error) {
+	q := make(url.Values)
+	q.Set("info_hash", string(ar.InfoHash[:]))
+	q.Set("peer_id", string(ar.PeerId[:]))
+	q.Set("port", fmt.Sprintf("%d", ar.Port))
+	q.Set("uploaded", strconv.FormatInt(ar.Uploaded, 10))
+	q.Set("downloaded", strconv.FormatInt(ar.Downloaded, 10))
+	q.Set("left", strconv.FormatInt(ar.Left, 10))
+	if ar.Event != tracker.None {
+		q.Set("event", ar.Event.String())
+	}
+	// http://stackoverflow.com/questions/17418004/why-does-tracker-server-not-understand-my-request-bittorrent-protocol
+	q.Set("compact", "1")
+	var reqURL url.URL = me.url
+	reqURL.RawQuery = q.Encode()
+	resp, err := http.Get(reqURL.String())
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+	buf := bytes.Buffer{}
+	io.Copy(&buf, resp.Body)
+	log.Printf("%q", buf.Bytes())
+	var trackerResponse response
+	err = bencode.NewDecoder(&buf).Decode(&trackerResponse)
+	if err != nil {
+		return
+	}
+	if trackerResponse.FailureReason != "" {
+		err = errors.New(trackerResponse.FailureReason)
+		return
+	}
+	ret.Interval = trackerResponse.Interval
+	ret.Leechers = trackerResponse.Incomplete
+	ret.Seeders = trackerResponse.Complete
+	ret.Peers, err = trackerResponse.UnmarshalPeers()
+	return
+}
+
+func (me *client) Connect() error {
+	// HTTP trackers do not require a connecting handshake.
+	return nil
+}
+
+func (me *client) String() string {
+	return me.URL()
+}
+
+func (me *client) URL() string {
+	return me.url.String()
+}
diff --git a/tracker/tracker.go b/tracker/tracker.go
index 888228ec..98a77a18 100644
--- a/tracker/tracker.go
+++ b/tracker/tracker.go
@@ -28,6 +28,11 @@ type AnnounceResponse struct {
 
 type AnnounceEvent int32
 
+func (me AnnounceEvent) String() string {
+	// See BEP 3, "event".
+	return []string{"empty", "completed", "started", "stopped"}[me]
+}
+
 type Peer struct {
 	IP   net.IP
 	Port int
-- 
2.48.1