118 lines
3.5 KiB
Go
118 lines
3.5 KiB
Go
package dpack
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"github.com/aceld/zinx/zlog"
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"github.com/aceld/zinx/zpack"
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"time"
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"github.com/aceld/zinx/zconf"
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"github.com/aceld/zinx/ziface"
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)
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// +---------------+---------------+--------------------+----------------+-------------------
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// | 开始标志 | type | 秒时间戳 | 长度 | 消息体
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// | 0xffff(2byte) | uint8(1byte) | uint32(4byte) | uint16(2byte) | bytes(N byte)
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// +---------------+---------------+--------------------+----------------+-------------------
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var defaultHeaderLen uint32 = 9
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type DataPack struct{}
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// NewDataPack initializes a packing and unpacking instance
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// (封包拆包实例初始化方法)
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func NewDataPack() ziface.IDataPack {
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return &DataPack{}
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}
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// GetHeadLen returns the length of the message header
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// (获取包头长度方法)
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func (dp *DataPack) GetHeadLen() uint32 {
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//ID uint32(4 bytes) + DataLen uint32(4 bytes)
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return defaultHeaderLen
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}
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// Pack packs the message (compresses the data)
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// (封包方法,压缩数据)
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func (dp *DataPack) Pack(msg ziface.IMessage) ([]byte, error) {
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zlog.Ins().InfoF("my pack: %v", msg)
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// Create a buffer to store the bytes
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// (创建一个存放bytes字节的缓冲)
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dataBuff := bytes.NewBuffer([]byte{})
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// Write the oxffff
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if err := binary.Write(dataBuff, binary.BigEndian, uint16(0xffff)); err != nil {
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return nil, err
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}
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//Write the type
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if err := binary.Write(dataBuff, binary.BigEndian, uint8(msg.GetMsgID())); err != nil {
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return nil, err
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}
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//Write the timestamp
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if err := binary.Write(dataBuff, binary.BigEndian, uint32(time.Now().Unix())); err != nil {
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return nil, err
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}
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//Write the length
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if err := binary.Write(dataBuff, binary.BigEndian, uint16(msg.GetDataLen())); err != nil {
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return nil, err
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}
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// Write the data
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if err := binary.Write(dataBuff, binary.BigEndian, msg.GetData()); err != nil {
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return nil, err
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}
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return dataBuff.Bytes(), nil
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}
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// Unpack unpacks the message (decompresses the data)
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// (拆包方法,解压数据)
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func (dp *DataPack) Unpack(binaryData []byte) (ziface.IMessage, error) {
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// Create an ioReader for the input binary data
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dataBuff := bytes.NewReader(binaryData)
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// Only unpack the header information to obtain the data length and message ID
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// (只解压head的信息，得到dataLen和msgID)
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msg := &zpack.Message{}
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// Read the startSign
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var startSign uint16
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if err := binary.Read(dataBuff, binary.BigEndian, &startSign); err != nil {
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return nil, err
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}
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// Read the msgID
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var msgType uint
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if err := binary.Read(dataBuff, binary.BigEndian, &msgType); err != nil {
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return nil, err
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}
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msg.ID = uint32(msgType)
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// read timeStamp
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var timeStamp uint32
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if err := binary.Read(dataBuff, binary.BigEndian, &timeStamp); err != nil {
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return nil, err
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}
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// Read the data length
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var length uint16
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if err := binary.Read(dataBuff, binary.BigEndian, &length); err != nil {
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return nil, err
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}
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msg.DataLen = uint32(length)
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// Check whether the data length exceeds the maximum allowed packet size
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// (判断dataLen的长度是否超出我们允许的最大包长度)
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if zconf.GlobalObject.MaxPacketSize > 0 && msg.GetDataLen() > zconf.GlobalObject.MaxPacketSize {
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return nil, errors.New("too large msg data received")
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}
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// Only the header data needs to be unpacked, and then another data read is performed from the connection based on the header length
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// (这里只需要把head的数据拆包出来就可以了，然后再通过head的长度，再从conn读取一次数据)
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return msg, nil
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}
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