19 func (i *Integer) Read(r io.Reader) error {
20 return binary.Read(r, binary.BigEndian, i)
23 // It's perfectly fine to cast these to an int.
24 func (i Integer) Int() int {
29 Protocol = "\x13BitTorrent protocol"
33 Choke MessageType = iota
49 AllowedFast = 0x11 // 17
53 HandshakeExtendedID = 0
55 RequestMetadataExtensionMsgType = 0
56 DataMetadataExtensionMsgType = 1
57 RejectMetadataExtensionMsgType = 2
63 Index, Begin, Length Integer
67 ExtendedPayload []byte
71 func (msg Message) MarshalBinary() (data []byte, err error) {
72 buf := &bytes.Buffer{}
74 err = buf.WriteByte(byte(msg.Type))
79 case Choke, Unchoke, Interested, NotInterested, HaveAll, HaveNone:
81 err = binary.Write(buf, binary.BigEndian, msg.Index)
82 case Request, Cancel, Reject:
83 for _, i := range []Integer{msg.Index, msg.Begin, msg.Length} {
84 err = binary.Write(buf, binary.BigEndian, i)
90 _, err = buf.Write(marshalBitfield(msg.Bitfield))
92 for _, i := range []Integer{msg.Index, msg.Begin} {
93 err = binary.Write(buf, binary.BigEndian, i)
98 n, err := buf.Write(msg.Piece)
102 if n != len(msg.Piece) {
106 err = buf.WriteByte(msg.ExtendedID)
110 _, err = buf.Write(msg.ExtendedPayload)
112 err = binary.Write(buf, binary.BigEndian, msg.Port)
114 err = fmt.Errorf("unknown message type: %v", msg.Type)
117 data = make([]byte, 4+buf.Len())
118 binary.BigEndian.PutUint32(data, uint32(buf.Len()))
119 if buf.Len() != copy(data[4:], buf.Bytes()) {
125 type Decoder struct {
128 MaxLength Integer // TODO: Should this include the length header or not?
131 func readByte(r io.Reader) (b byte, err error) {
133 n, err := r.Read(arr[:])
145 // io.EOF is returned if the source terminates cleanly on a message boundary.
146 func (d *Decoder) Decode(msg *Message) (err error) {
148 err = binary.Read(d.R, binary.BigEndian, &length)
151 err = fmt.Errorf("error reading message length: %s", err)
155 if length > d.MaxLength {
156 return errors.New("message too long")
162 msg.Keepalive = false
163 r := &io.LimitedReader{d.R, int64(length)}
164 // Check that all of r was utilized.
170 err = fmt.Errorf("%d bytes unused in message type %d", r.N, msg.Type)
173 msg.Keepalive = false
174 c, err := readByte(r)
178 msg.Type = MessageType(c)
180 case Choke, Unchoke, Interested, NotInterested, HaveAll, HaveNone:
183 err = msg.Index.Read(r)
184 case Request, Cancel, Reject:
185 for _, data := range []*Integer{&msg.Index, &msg.Begin, &msg.Length} {
192 b := make([]byte, length-1)
193 _, err = io.ReadFull(r, b)
194 msg.Bitfield = unmarshalBitfield(b)
196 for _, pi := range []*Integer{&msg.Index, &msg.Begin} {
205 //msg.Piece, err = ioutil.ReadAll(r)
206 b := d.Pool.Get().([]byte)
207 n, err := io.ReadFull(r, b)
209 if err != io.ErrUnexpectedEOF || n != int(length-9) {
216 msg.ExtendedID, err = readByte(r)
220 msg.ExtendedPayload, err = ioutil.ReadAll(r)
222 err = binary.Read(r, binary.BigEndian, &msg.Port)
224 err = fmt.Errorf("unknown message type %#v", c)
231 func (b Bytes) MarshalBinary() ([]byte, error) {
235 func unmarshalBitfield(b []byte) (bf []bool) {
236 for _, c := range b {
237 for i := 7; i >= 0; i-- {
238 bf = append(bf, (c>>uint(i))&1 == 1)
244 func marshalBitfield(bf []bool) (b []byte) {
245 b = make([]byte, (len(bf)+7)/8)
246 for i, have := range bf {
251 c |= 1 << uint(7-i%8)