Implement handshake.New()

handshake/handshake.go

@@ -12,6 +12,15 @@ type Handshake struct {
 	PeerID   [20]byte
 }
 
+// New creates a new handshake with the standard pstr
+func New(infoHash, peerID [20]byte) *Handshake {
+	return &Handshake{
+		Pstr:     "BitTorrent protocol",
+		InfoHash: infoHash,
+		PeerID:   peerID,
+	}
+}
+
 // Serialize serializes the handshake to a buffer
 func (h *Handshake) Serialize() []byte {
 	pstrlen := len(h.Pstr)

handshake/handshake_test.go

@@ -7,6 +7,18 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestNew(t *testing.T) {
+	infoHash := [20]byte{134, 212, 200, 0, 36, 164, 105, 190, 76, 80, 188, 90, 16, 44, 247, 23, 128, 49, 0, 116}
+	peerID := [20]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
+	h := New(infoHash, peerID)
+	expected := &Handshake{
+		Pstr:     "BitTorrent protocol",
+		InfoHash: [20]byte{134, 212, 200, 0, 36, 164, 105, 190, 76, 80, 188, 90, 16, 44, 247, 23, 128, 49, 0, 116},
+		PeerID:   [20]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20},
+	}
+	assert.Equal(t, expected, h)
+}
+
 func TestSerialize(t *testing.T) {
 	tests := map[string]struct {
 		input  *Handshake

p2p/p2p.go

@@ -100,11 +100,7 @@ func (p *Peer) connect(peerID [20]byte, infoHash [20]byte) (net.Conn, error) {
 }
 
 func (d *Downloader) handshake(conn net.Conn) (*handshake.Handshake, error) {
-	req := handshake.Handshake{
-		Pstr:     "BitTorrent protocol",
-		InfoHash: d.InfoHash,
-		PeerID:   d.PeerID,
-	}
+	req := handshake.New(d.InfoHash, d.PeerID)
 	_, err := conn.Write(req.Serialize())
 	if err != nil {
 		return nil, err