diff --git a/p2p/p2p.go b/p2p/p2p.go index 8d0d461..12f0cbf 100644 --- a/p2p/p2p.go +++ b/p2p/p2p.go @@ -1,8 +1,15 @@ package p2p import ( + "crypto/sha1" + "encoding/binary" + "encoding/hex" + "fmt" + "math" "net" "strconv" + + "github.com/veggiedefender/torrent-client/message" ) // Peer encodes connection information for a peer @@ -13,17 +20,75 @@ type Peer struct { // Downloader holds data required to download a torrent from a list of peers type Downloader struct { - Peers []Peer - InfoHash [20]byte - Length int + Peers []Peer + PeerID [20]byte + InfoHash [20]byte + PieceHashes [][20]byte + Length int } // Download downloads a torrent func (d *Downloader) Download() error { + conn, err := d.Peers[0].connect(d.PeerID, d.InfoHash) + defer conn.Close() + if err != nil { + return err + } + _, err = d.handshake(conn) + if err != nil { + return err + } + + choked := false + pieceSize := d.Length / len(d.PieceHashes) + buf := make([]byte, pieceSize) + i := 0 + for i < pieceSize { + msg, err := message.ReadMessage(conn) + if err != nil { + return err + } + + switch msg.ID { + case message.MsgChoke: + choked = true + case message.MsgUnchoke: + choked = false + case message.MsgPiece: + begin := binary.BigEndian.Uint32(msg.Payload[4:8]) + copy(buf[begin:], msg.Payload[8:]) + i += (len(msg.Payload) - 8) + } + + if !choked { + index := 0 // Piece number + begin := i // Offset + remain := pieceSize - i + length := int(math.Min(float64(16384), float64(pieceSize))) + length = int(math.Min(float64(remain), float64(length))) + payload := make([]byte, 12) + binary.BigEndian.PutUint32(payload[0:4], uint32(index)) + binary.BigEndian.PutUint32(payload[4:8], uint32(begin)) + binary.BigEndian.PutUint32(payload[8:12], uint32(length)) + request := message.Message{ + ID: message.MsgRequest, + Payload: payload, + } + _, err := conn.Write(request.Serialize()) + if err != nil { + return err + } + } + } + + s := sha1.Sum(buf) + fmt.Println(hex.EncodeToString(s[:])) + fmt.Println(hex.EncodeToString(d.PieceHashes[0][:])) + return nil } -func connect(p *Peer, peerID [20]byte, infoHash [20]byte) (net.Conn, error) { +func (p *Peer) connect(peerID [20]byte, infoHash [20]byte) (net.Conn, error) { hostPort := net.JoinHostPort(p.IP.String(), strconv.Itoa(int(p.Port))) conn, err := net.Dial("tcp", hostPort) if err != nil { @@ -31,3 +96,21 @@ func connect(p *Peer, peerID [20]byte, infoHash [20]byte) (net.Conn, error) { } return conn, nil } + +func (d *Downloader) handshake(conn net.Conn) (*message.Handshake, error) { + req := message.Handshake{ + Pstr: "BitTorrent protocol", + InfoHash: d.InfoHash, + PeerID: d.PeerID, + } + _, err := conn.Write(req.Serialize()) + if err != nil { + return nil, err + } + + res, err := message.ReadHandshake(conn) + if err != nil { + return nil, err + } + return res, nil +} diff --git a/torrent/torrent.go b/torrent/torrent.go index 10a4cae..44a642b 100644 --- a/torrent/torrent.go +++ b/torrent/torrent.go @@ -49,9 +49,11 @@ func (t *Torrent) Download() error { // fmt.Println(peers) peers := []p2p.Peer{{IP: net.IP{127, 0, 0, 1}, Port: 51413}} downloader := p2p.Downloader{ - Peers: peers, - InfoHash: t.InfoHash, - Length: t.Length, + Peers: peers, + PeerID: peerID, + InfoHash: t.InfoHash, + PieceHashes: t.PieceHashes, + Length: t.Length, } err = downloader.Download() return err