feat(tracker): request peers

pkg/torrentfile/torrentfile.go

@@ -1,8 +1,13 @@
 package torrentfile
 
 import (
+	"net/http"
 	"net/url"
 	"strconv"
+	"time"
+
+	"github.com/brianlusina/tclient/pkg/peers"
+	"github.com/jackpal/bencode-go"
 )
 
 // Port to listen on
@@ -18,6 +23,11 @@ type TorrentFile struct {
 	Name        string
 }
 
+type bencodeTrackerResp struct {
+	Interval int    `bencode:"interval"`
+	Peers    string `bencode:"peers"`
+}
+
 func (t *TorrentFile) buildTrackerUrl(peerId [20]byte, port uint16) (string, error) {
 	base, err := url.Parse(t.Announce)
 
@@ -38,3 +48,26 @@ func (t *TorrentFile) buildTrackerUrl(peerId [20]byte, port uint16) (string, err
 	base.RawQuery = params.Encode()
 	return base.String(), nil
 }
+
+func (t *TorrentFile) requestPeers(peerID [20]byte, port uint16) ([]peers.Peer, error) {
+	url, err := t.buildTrackerUrl(peerID, port)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &http.Client{Timeout: 15 * time.Second}
+	resp, err := c.Get(url)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	trackerResp := bencodeTrackerResp{}
+	err = bencode.Unmarshal(resp.Body, &trackerResp)
+	if err != nil {
+		return nil, err
+	}
+
+	return peers.Unmarshal([]byte(trackerResp.Peers))
+}

pkg/torrentfile/torrentfile_test.go

@@ -1,39 +1,18 @@
 package torrentfile
 
 import (
-	"encoding/json"
 	"flag"
-	"io/ioutil"
+	"net"
+	"net/http"
+	"net/http/httptest"
 	"testing"
 
+	"github.com/brianlusina/tclient/pkg/peers"
 	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 var update = flag.Bool("update", false, "update .golden.json files")
 
-func TestOpen(t *testing.T) {
-	torrent, err := Open("testdata/archlinux-2019.12.01-x86_64.iso.torrent")
-	require.Nil(t, err)
-
-	goldenPath := "testdata/archlinux-2019.12.01-x86_64.iso.torrent.golden.json"
-
-	if *update {
-		serialized, err := json.MarshalIndent(torrent, "", "  ")
-		require.Nil(t, err)
-		ioutil.WriteFile(goldenPath, serialized, 0644)
-	}
-
-	expected := TorrentFile{}
-	golden, err := ioutil.ReadFile(goldenPath)
-	require.Nil(t, err)
-
-	err = json.Unmarshal(golden, &expected)
-	require.Nil(t, err)
-
-	assert.Equal(t, expected, torrent)
-}
-
 func TestBuildTrackerUrl(t *testing.T) {
 	to := TorrentFile{
 		Announce: "http://bttracker.debian.org:6969/announce",
@@ -54,3 +33,38 @@ func TestBuildTrackerUrl(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, url, expected)
 }
+
+func TestRequestPeers(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		response := []byte(
+			"d" +
+				"8:interval" + "i900e" +
+				"5:peers" + "12:" +
+				string([]byte{
+					192, 0, 2, 123, 0x1A, 0xE1, // 0x1AE1 = 6881
+					127, 0, 0, 1, 0x1A, 0xE9, // 0x1AE9 = 6889
+				}) + "e")
+		w.Write(response)
+	}))
+	defer ts.Close()
+	tf := TorrentFile{
+		Announce: ts.URL,
+		InfoHash: [20]byte{216, 247, 57, 206, 195, 40, 149, 108, 204, 91, 191, 31, 134, 217, 253, 207, 219, 168, 206, 182},
+		PieceHashes: [][20]byte{
+			{49, 50, 51, 52, 53, 54, 55, 56, 57, 48, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106},
+			{97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 49, 50, 51, 52, 53, 54, 55, 56, 57, 48},
+		},
+		PieceLength: 262144,
+		Length:      351272960,
+		Name:        "debian-10.2.0-amd64-netinst.iso",
+	}
+	peerID := [20]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
+	const port uint16 = 6882
+	expected := []peers.Peer{
+		{IP: net.IP{192, 0, 2, 123}, Port: 6881},
+		{IP: net.IP{127, 0, 0, 1}, Port: 6889},
+	}
+	p, err := tf.requestPeers(peerID, port)
+	assert.Nil(t, err)
+	assert.Equal(t, expected, p)
+}

pkg/torrentfile/utils_test.go

@@ -0,0 +1,32 @@
+package torrentfile
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestOpen(t *testing.T) {
+	torrent, err := Open("testdata/archlinux-2019.12.01-x86_64.iso.torrent")
+	require.Nil(t, err)
+
+	goldenPath := "testdata/archlinux-2019.12.01-x86_64.iso.torrent.golden.json"
+
+	if *update {
+		serialized, err := json.MarshalIndent(torrent, "", "  ")
+		require.Nil(t, err)
+		ioutil.WriteFile(goldenPath, serialized, 0644)
+	}
+
+	expected := TorrentFile{}
+	golden, err := ioutil.ReadFile(goldenPath)
+	require.Nil(t, err)
+
+	err = json.Unmarshal(golden, &expected)
+	require.Nil(t, err)
+
+	assert.Equal(t, expected, torrent)
+}