135 lines
2.9 KiB
Go
135 lines
2.9 KiB
Go
package packet
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import (
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"bytes"
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"compress/zlib"
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"fmt"
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"io"
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)
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// Packet define a net data package
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type Packet struct {
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ID int32
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Data []byte
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}
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//Marshal generate Packet with the ID and Fields
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func Marshal(id int32, fields ...FieldEncoder) (pk Packet) {
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pk.ID = id
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for _, v := range fields {
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pk.Data = append(pk.Data, v.Encode()...)
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}
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return
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}
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//Scan decode the packet and fill data into fields
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func (p Packet) Scan(fields ...FieldDecoder) error {
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r := bytes.NewReader(p.Data)
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for _, v := range fields {
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err := v.Decode(r)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Pack 打包一个数据包
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func (p *Packet) Pack(threshold int) (pack []byte) {
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d := append(VarInt(p.ID).Encode(), p.Data...)
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if threshold > 0 { //是否启用了压缩
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if len(d) > threshold { //是否需要压缩
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Len := len(d)
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VarLen := VarInt(Len).Encode()
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d = compress(d)
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pack = append(pack, VarInt(len(VarLen)+len(d)).Encode()...)
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pack = append(pack, VarLen...)
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pack = append(pack, d...)
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} else {
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pack = append(pack, VarInt(int32(len(d)+1)).Encode()...)
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pack = append(pack, 0x00)
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pack = append(pack, d...)
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}
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} else {
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pack = append(pack, VarInt(int32(len(d))).Encode()...) //len
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pack = append(pack, d...)
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}
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return
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}
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// UnPack in-place decompression a packet
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func (p *Packet) UnPack(r DecodeReader, threshold int) error {
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var length VarInt
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if err := length.Decode(r); err != nil {
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return err
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}
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if length < 1 {
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return fmt.Errorf("packet length too short")
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}
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buf := bytes.NewBuffer(p.Data[:0])
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if _, err := io.CopyN(buf, r, int64(length)); err != nil {
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return fmt.Errorf("read content of packet fail: %w", err)
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}
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//解压数据
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if threshold > 0 {
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if err := unCompress(buf); err != nil {
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return err
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}
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}
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var packetID VarInt
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if err := packetID.Decode(buf); err != nil {
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return fmt.Errorf("read packet id fail: %v", err)
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}
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p.ID = int32(packetID)
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p.Data = buf.Bytes()
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return nil
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}
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// unCompress 读取一个压缩的包
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func unCompress(data *bytes.Buffer) error {
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reader := bytes.NewReader(data.Bytes())
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var sizeUncompressed VarInt
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if err := sizeUncompressed.Decode(reader); err != nil {
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return err
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}
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var uncompressedData []byte
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if sizeUncompressed != 0 { // != 0 means compressed, let's decompress
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uncompressedData = make([]byte, sizeUncompressed)
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r, err := zlib.NewReader(reader)
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if err != nil {
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return fmt.Errorf("decompress fail: %v", err)
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}
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defer r.Close()
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_, err = io.ReadFull(r, uncompressedData)
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if err != nil {
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return fmt.Errorf("decompress fail: %v", err)
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}
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} else {
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uncompressedData = data.Bytes()[1:]
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}
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*data = *bytes.NewBuffer(uncompressedData)
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return nil
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}
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// compress 压缩数据
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func compress(data []byte) []byte {
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var b bytes.Buffer
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w := zlib.NewWriter(&b)
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if _, err := w.Write(data); err != nil {
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panic(err)
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}
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if err := w.Close(); err != nil {
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panic(err)
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}
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return b.Bytes()
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}
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