diff --git a/downloader/torrent_info.go b/downloader/torrent.go
similarity index 82%
rename from downloader/torrent_info.go
rename to downloader/torrent.go
index d641975..1dda197 100644
--- a/downloader/torrent_info.go
+++ b/downloader/torrent.go
@@ -26,7 +26,7 @@ import (
 	"strconv"
 
 	"github.com/xgfone/bt/metainfo"
-	"github.com/xgfone/bt/peerprotocol"
+	pp "github.com/xgfone/bt/peerprotocol"
 )
 
 const peerBlockSize = 16384 // 16KiB.
@@ -90,8 +90,8 @@ type TorrentDownloader struct {
 	responses chan TorrentResponse
 
 	ondht func(string, uint16)
-	ebits peerprotocol.ExtensionBits
-	ehmsg peerprotocol.ExtendedHandshakeMsg
+	ebits pp.ExtensionBits
+	ehmsg pp.ExtendedHandshakeMsg
 }
 
 // NewTorrentDownloader returns a new TorrentDownloader.
@@ -107,8 +107,8 @@ func NewTorrentDownloader(c ...TorrentDownloaderConfig) *TorrentDownloader {
 		requests:  make(chan request, conf.WorkerNum),
 		responses: make(chan TorrentResponse, 1024),
 
-		ehmsg: peerprotocol.ExtendedHandshakeMsg{
-			M: map[string]uint8{peerprotocol.ExtendedMessageNameMetadata: 1},
+		ehmsg: pp.ExtendedHandshakeMsg{
+			M: map[string]uint8{pp.ExtendedMessageNameMetadata: 1},
 		},
 	}
 
@@ -116,7 +116,7 @@ func NewTorrentDownloader(c ...TorrentDownloaderConfig) *TorrentDownloader {
 		go d.worker()
 	}
 
-	d.ebits.Set(peerprotocol.ExtensionBitExtended)
+	d.ebits.Set(pp.ExtensionBitExtended)
 	return d
 }
 
@@ -151,9 +151,9 @@ func (d *TorrentDownloader) Close() {
 func (d *TorrentDownloader) OnDHTNode(cb func(host string, port uint16)) {
 	d.ondht = cb
 	if cb == nil {
-		d.ebits.Unset(peerprotocol.ExtensionBitDHT)
+		d.ebits.Unset(pp.ExtensionBitDHT)
 	} else {
-		d.ebits.Set(peerprotocol.ExtensionBitDHT)
+		d.ebits.Set(pp.ExtensionBitDHT)
 	}
 }
 
@@ -174,18 +174,19 @@ func (d *TorrentDownloader) worker() {
 func (d *TorrentDownloader) download(host string, port uint16,
 	peerID, infohash metainfo.Hash) (err error) {
 	addr := net.JoinHostPort(host, strconv.FormatUint(uint64(port), 10))
-	conn, err := peerprotocol.NewPeerConnByDial(d.conf.ID, addr)
+	conn, err := pp.NewPeerConnByDial(addr, d.conf.ID, infohash)
 	if err != nil {
 		return fmt.Errorf("fail to dial to '%s': %s", addr, err)
 	}
 	defer conn.Close()
 
-	conn.ExtensionBits = d.ebits
-	rmsg, err := conn.Handshake(infohash)
-	if err != nil || rmsg.InfoHash != infohash || !rmsg.IsSupportExtended() {
+	conn.ExtBits = d.ebits
+	if err = conn.Handshake(); err != nil {
 		return
-	} else if !peerID.IsZero() && peerID != rmsg.PeerID {
-		return fmt.Errorf("inconsistent peer id '%s'", rmsg.PeerID.HexString())
+	} else if !conn.PeerExtBits.IsSupportExtended() {
+		return fmt.Errorf("the remote peer '%s' does not support Extended", addr)
+	} else if !peerID.IsZero() && peerID != conn.PeerID {
+		return fmt.Errorf("inconsistent peer id '%s'", conn.PeerID.HexString())
 	}
 
 	if err = conn.SendExtHandshakeMsg(d.ehmsg); err != nil {
@@ -196,7 +197,7 @@ func (d *TorrentDownloader) download(host string, port uint16,
 	var piecesNum int
 	var metadataSize int
 	var utmetadataID uint8
-	var msg peerprotocol.Message
+	var msg pp.Message
 
 	for {
 		if msg, err = conn.ReadMsg(); err != nil {
@@ -214,8 +215,8 @@ func (d *TorrentDownloader) download(host string, port uint16,
 		}
 
 		switch msg.Type {
-		case peerprotocol.Extended:
-		case peerprotocol.Port:
+		case pp.Extended:
+		case pp.Port:
 			if d.ondht != nil {
 				d.ondht(host, msg.Port)
 			}
@@ -225,17 +226,17 @@ func (d *TorrentDownloader) download(host string, port uint16,
 		}
 
 		switch msg.ExtendedID {
-		case peerprotocol.ExtendedIDHandshake:
+		case pp.ExtendedIDHandshake:
 			if utmetadataID > 0 {
 				return fmt.Errorf("rehandshake from the peer '%s'", conn.RemoteAddr().String())
 			}
 
-			var ehmsg peerprotocol.ExtendedHandshakeMsg
+			var ehmsg pp.ExtendedHandshakeMsg
 			if err = ehmsg.Decode(msg.ExtendedPayload); err != nil {
 				return
 			}
 
-			utmetadataID = ehmsg.M[peerprotocol.ExtendedMessageNameMetadata]
+			utmetadataID = ehmsg.M[pp.ExtendedMessageNameMetadata]
 			if utmetadataID == 0 {
 				return errors.New(`the peer does not support "ut_metadata"`)
 			}
@@ -253,12 +254,12 @@ func (d *TorrentDownloader) download(host string, port uint16,
 				return
 			}
 
-			var utmsg peerprotocol.UtMetadataExtendedMsg
+			var utmsg pp.UtMetadataExtendedMsg
 			if err = utmsg.DecodeFromPayload(msg.ExtendedPayload); err != nil {
 				return
 			}
 
-			if utmsg.MsgType != peerprotocol.UtMetadataExtendedMsgTypeData {
+			if utmsg.MsgType != pp.UtMetadataExtendedMsgTypeData {
 				continue
 			}
 
@@ -283,7 +284,7 @@ func (d *TorrentDownloader) download(host string, port uint16,
 					d.responses <- TorrentResponse{
 						Host:      host,
 						Port:      port,
-						PeerID:    rmsg.PeerID,
+						PeerID:    conn.PeerID,
 						InfoHash:  infohash,
 						InfoBytes: metadataInfo,
 					}
@@ -294,18 +295,18 @@ func (d *TorrentDownloader) download(host string, port uint16,
 	}
 }
 
-func (d *TorrentDownloader) requestPieces(conn *peerprotocol.PeerConn, utMetadataID uint8, piecesNum int) {
+func (d *TorrentDownloader) requestPieces(conn *pp.PeerConn, utMetadataID uint8, piecesNum int) {
 	for i := 0; i < piecesNum; i++ {
-		payload, err := peerprotocol.UtMetadataExtendedMsg{
-			MsgType: peerprotocol.UtMetadataExtendedMsgTypeRequest,
+		payload, err := pp.UtMetadataExtendedMsg{
+			MsgType: pp.UtMetadataExtendedMsgTypeRequest,
 			Piece:   i,
 		}.EncodeToBytes()
 		if err != nil {
 			panic(err)
 		}
 
-		msg := peerprotocol.Message{
-			Type:            peerprotocol.Extended,
+		msg := pp.Message{
+			Type:            pp.Extended,
 			ExtendedID:      utMetadataID,
 			ExtendedPayload: payload,
 		}