单个peer的文件下载实现

down/bt/metainfo/metainfo.go

@@ -22,7 +22,9 @@ type MetaInfo struct {
 	UrlList []string `json:"url-list"`
 	Info    *Info    `json:"info"`
 
-	ExtraInfo `json:"-"`
+	infoHash    [20]byte     `json:"-"`
+	totalSize   uint64       `json:"-"`
+	fileDetails []FileDetail `json:"-"`
 }
 
 type Info struct {
@@ -34,13 +36,15 @@ type Info struct {
 }
 
 type File struct {
-	Length uint64 `json:"length"`
-	Path   string `json:"path"`
+	Length uint64   `json:"length"`
+	Path   []string `json:"path"`
 }
 
-type ExtraInfo struct {
-	InfoHash  [20]byte
-	TotalSize uint64
+type FileDetail struct {
+	Length uint64
+	Path   []string
+	Begin  int64
+	End    int64
 }
 
 func ParseFromFile(path string) (*MetaInfo, error) {
@@ -63,7 +67,7 @@ func ParseFromFile(path string) (*MetaInfo, error) {
 		// encode info hash
 		info := btDecode["info"].(map[string]interface{})
 		infoBtEncode := bencode.Encode(info)
-		metaInfo.InfoHash = sha1.Sum(infoBtEncode[:])
+		metaInfo.infoHash = sha1.Sum(infoBtEncode[:])
 		// Split pieces hash
 		pieces := info["pieces"].(string)
 		if pieces != "" {
@@ -75,33 +79,56 @@ func ParseFromFile(path string) (*MetaInfo, error) {
 			}
 		}
 	}
-	metaInfo.TotalSize = getTotalSize(&metaInfo)
+	calcFileSize(&metaInfo)
 	return &metaInfo, nil
 }
 
 // 获取某个分片的大小
 func (metaInfo *MetaInfo) GetPieceSize(index int) uint64 {
 	// 是否为最后一个分片
 	if index == len(metaInfo.Info.Pieces)-1 {
-		size := metaInfo.TotalSize % metaInfo.Info.PieceLength
+		size := metaInfo.totalSize % metaInfo.Info.PieceLength
 		if size > 0 {
 			return size
 		}
 	}
 	return metaInfo.Info.PieceLength
 }
 
-func getTotalSize(metaInfo *MetaInfo) uint64 {
+// 获取所有文件的大小
+func (metaInfo *MetaInfo) GetTotalSize() uint64 {
+	return metaInfo.totalSize
+}
+
+// 获取info hash
+func (metaInfo *MetaInfo) GetInfoHash() [20]byte {
+	return metaInfo.infoHash
+}
+
+// 获取所有文件的开始偏移字节
+func (metaInfo *MetaInfo) GetFileDetails() []FileDetail {
+	return metaInfo.fileDetails
+}
+
+// 计算所有文件的大小
+func calcFileSize(metaInfo *MetaInfo) {
 	if metaInfo.Info != nil {
-		if len(metaInfo.Info.Files) > 0 {
+		fileCount := len(metaInfo.Info.Files)
+		if fileCount > 0 {
+			metaInfo.fileDetails = make([]FileDetail, fileCount)
 			var length uint64
-			for _, f := range metaInfo.Info.Files {
+			for i, f := range metaInfo.Info.Files {
+				metaInfo.fileDetails[i] = FileDetail{
+					Length: f.Length,
+					Path:   f.Path,
+					Begin:  int64(length),
+					End:    int64(length + f.Length),
+				}
 				length += f.Length
 			}
-			return length
+			metaInfo.totalSize = length
 		} else {
-			return metaInfo.Info.Length
+			metaInfo.totalSize = metaInfo.Info.Length
 		}
 	}
-	return 0
 }

down/bt/metainfo/metainfo_test.go

@@ -10,5 +10,6 @@ func TestParseFromFile(t *testing.T) {
 	if err != nil {
 		panic(err)
 	}
-	fmt.Println(metaInfo)
+	fmt.Printf("%+v\n", metaInfo)
+	fmt.Printf("%+v\n", metaInfo.Info.Files)
 }

down/bt/peer/message/message.go

@@ -29,14 +29,14 @@ type Message struct {
 	ID     ID
 }
 
-func (msg Message) Encode() []byte {
+func (msg *Message) Encode() []byte {
 	buf := make([]byte, 5)
 	binary.BigEndian.PutUint32(buf, msg.Length)
 	buf[4] = byte(msg.ID)
 	return buf
 }
 
-func (msg Message) Decode(buf []byte) {
+func (msg *Message) Decode(buf []byte) {
 	msg.Length = binary.BigEndian.Uint32(buf)
 	msg.ID = ID(buf[4])
 }

down/bt/peer/message/msg_bitfield.go

@@ -2,13 +2,13 @@ package message
 
 // bitfield: <len=0001+X><id=5><bitfield>
 type Bitfield struct {
-	Message
+	*Message
 	payload []byte
 }
 
 func NewBitfield(payload []byte) *Bitfield {
 	return &Bitfield{
-		Message: Message{
+		Message: &Message{
 			Length: uint32(len(payload) + 1),
 			ID:     IdBitfield,
 		},
@@ -21,8 +21,9 @@ func (b *Bitfield) Encode() []byte {
 }
 
 func (b *Bitfield) Decode(buf []byte) Serialize {
+	b.Message = &Message{}
 	b.Message.Decode(buf)
-	copy(b.payload, buf[5:])
+	b.payload = buf[5:]
 	return b
 }
 

down/bt/peer/message/msg_piece.go

@@ -1,23 +1,41 @@
 package message
 
-import "io"
+import "encoding/binary"
 
 // piece: <len=0009+X><id=7><index><begin><block>
 type Piece struct {
-	Message
+	*Message
 	Index uint32
 	Begin uint32
-	Block io.Reader
+	Block []byte
 }
 
-func newPiece(index uint32, begin uint32, reader io.Reader, length uint32) *Piece {
+func NewPiece(index uint32, begin uint32, block []byte) *Piece {
 	return &Piece{
-		Message: Message{
-			Length: 9 + length,
+		Message: &Message{
+			Length: 9 + uint32(len(block)),
 			ID:     IdPiece,
 		},
 		Index: index,
 		Begin: begin,
-		Block: io.LimitReader(reader, int64(length)),
+		// Block: io.LimitReader(reader, int64(length)),
+		Block: block,
 	}
 }
+
+func (p *Piece) Encode() []byte {
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint32(buf[:4], p.Index)
+	binary.BigEndian.PutUint32(buf[4:8], p.Begin)
+	buf = append(buf, p.Block...)
+	return append(p.Message.Encode(), buf...)
+}
+
+func (p *Piece) Decode(buf []byte) Serialize {
+	p.Message = &Message{}
+	p.Message.Decode(buf)
+	p.Index = binary.BigEndian.Uint32(buf[5:9])
+	p.Begin = binary.BigEndian.Uint32(buf[9:13])
+	p.Block = buf[13:]
+	return p
+}

down/bt/peer/message/msg_request.go

@@ -26,9 +26,9 @@ func NewRequest(index uint32, begin uint32, length uint32) *Request {
 
 func (r *Request) Encode() []byte {
 	buf := make([]byte, 12)
-	binary.BigEndian.PutUint32(buf[:4], r.Index)
+	binary.BigEndian.PutUint32(buf[0:4], r.Index)
 	binary.BigEndian.PutUint32(buf[4:8], r.Begin)
-	binary.BigEndian.PutUint32(buf[8:], r.Length)
+	binary.BigEndian.PutUint32(buf[8:12], r.Length)
 	return append(r.Message.Encode(), buf...)
 }