Refactor p2p

torrentfile/torrentfile.go

@@ -0,0 +1,122 @@
+package torrentfile
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/sha1"
+	"fmt"
+	"io"
+
+	"github.com/jackpal/bencode-go"
+	"github.com/veggiedefender/torrent-client/p2p"
+)
+
+// Port to listen on
+const Port uint16 = 6881
+
+// TorrentFile encodes the metadata from a .torrent file
+type TorrentFile struct {
+	Announce    string
+	InfoHash    [20]byte
+	PieceHashes [][20]byte
+	PieceLength int
+	Length      int
+	Name        string
+}
+
+type bencodeInfo struct {
+	Pieces      string `bencode:"pieces"`
+	PieceLength int    `bencode:"piece length"`
+	Length      int    `bencode:"length"`
+	Name        string `bencode:"name"`
+}
+
+type bencodeTorrent struct {
+	Announce string      `bencode:"announce"`
+	Info     bencodeInfo `bencode:"info"`
+}
+
+// Download downloads a torrent
+func (t *TorrentFile) Download() ([]byte, error) {
+	var peerID [20]byte
+	_, err := rand.Read(peerID[:])
+	if err != nil {
+		return nil, err
+	}
+
+	peers, err := t.getPeers(peerID, Port)
+	// peers = append(peers, p2p.Peer{IP: net.IP{127, 0, 0, 1}, Port: 51413})
+	// peers := []p2p.Peer{{IP: net.IP{127, 0, 0, 1}, Port: 51413}}
+	torrent := p2p.Torrent{
+		Peers:       peers,
+		PeerID:      peerID,
+		InfoHash:    t.InfoHash,
+		PieceHashes: t.PieceHashes,
+		Length:      t.Length,
+	}
+	buf, err := torrent.Download()
+	if err != nil {
+		return nil, err
+	}
+	return buf, nil
+}
+
+// Open parses a torrent file
+func Open(r io.Reader) (*TorrentFile, error) {
+	bto := bencodeTorrent{}
+	err := bencode.Unmarshal(r, &bto)
+	if err != nil {
+		return nil, err
+	}
+	t, err := bto.toTorrent()
+	if err != nil {
+		return nil, err
+	}
+	return t, nil
+}
+
+func (i *bencodeInfo) hash() ([20]byte, error) {
+	var buf bytes.Buffer
+	err := bencode.Marshal(&buf, *i)
+	if err != nil {
+		return [20]byte{}, err
+	}
+	h := sha1.Sum(buf.Bytes())
+	return h, nil
+}
+
+func (i *bencodeInfo) splitPieceHashes() ([][20]byte, error) {
+	hashLen := 20 // Length of SHA-1 hash
+	buf := []byte(i.Pieces)
+	if len(buf)%hashLen != 0 {
+		err := fmt.Errorf("Received malformed pieces of length %d", len(buf))
+		return nil, err
+	}
+	numHashes := len(buf) / hashLen
+	hashes := make([][20]byte, numHashes)
+
+	for i := 0; i < numHashes; i++ {
+		copy(hashes[i][:], buf[i*hashLen:(i+1)*hashLen])
+	}
+	return hashes, nil
+}
+
+func (bto *bencodeTorrent) toTorrent() (*TorrentFile, error) {
+	infoHash, err := bto.Info.hash()
+	if err != nil {
+		return nil, err
+	}
+	pieceHashes, err := bto.Info.splitPieceHashes()
+	if err != nil {
+		return nil, err
+	}
+	t := TorrentFile{
+		Announce:    bto.Announce,
+		InfoHash:    infoHash,
+		PieceHashes: pieceHashes,
+		PieceLength: bto.Info.PieceLength,
+		Length:      bto.Info.Length,
+		Name:        bto.Info.Name,
+	}
+	return &t, nil
+}