88 lines
2.0 KiB
Go
88 lines
2.0 KiB
Go
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package packets
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import (
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"bytes"
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"fmt"
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"io"
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"github.com/winc-link/hummingbird/internal/pkg/codes"
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)
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// Suback represents the MQTT Suback packet.
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type Suback struct {
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Version Version
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FixHeader *FixHeader
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PacketID PacketID
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Payload []codes.Code
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Properties *Properties
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}
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func (p *Suback) String() string {
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return fmt.Sprintf("Suback,Version: %v, Pid: %v, Payload: %v, Properties: %s", p.Version, p.PacketID, p.Payload, p.Properties)
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}
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// NewSubackPacket returns a Suback instance by the given FixHeader and io.Reader.
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func NewSubackPacket(fh *FixHeader, version Version, r io.Reader) (*Suback, error) {
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p := &Suback{FixHeader: fh, Version: version}
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//判断 标志位 flags 是否合法[MQTT-3.8.1-1]
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if fh.Flags != FlagReserved {
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return nil, codes.ErrMalformed
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}
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err := p.Unpack(r)
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return p, err
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}
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// Pack encodes the packet struct into bytes and writes it into io.Writer.
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func (p *Suback) Pack(w io.Writer) error {
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p.FixHeader = &FixHeader{PacketType: SUBACK, Flags: FlagReserved}
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bufw := &bytes.Buffer{}
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writeUint16(bufw, p.PacketID)
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if p.Version == Version5 {
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p.Properties.Pack(bufw, SUBACK)
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}
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bufw.Write(p.Payload)
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p.FixHeader.RemainLength = bufw.Len()
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err := p.FixHeader.Pack(w)
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if err != nil {
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return err
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}
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_, err = bufw.WriteTo(w)
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return err
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}
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// Unpack read the packet bytes from io.Reader and decodes it into the packet struct.
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func (p *Suback) Unpack(r io.Reader) error {
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restBuffer := make([]byte, p.FixHeader.RemainLength)
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_, err := io.ReadFull(r, restBuffer)
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if err != nil {
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return codes.ErrMalformed
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}
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bufr := bytes.NewBuffer(restBuffer)
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p.PacketID, err = readUint16(bufr)
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if err != nil {
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return codes.ErrMalformed
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}
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if p.Version == Version5 {
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p.Properties = &Properties{}
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err = p.Properties.Unpack(bufr, SUBACK)
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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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for {
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b, err := bufr.ReadByte()
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if err != nil {
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return codes.ErrMalformed
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}
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if !ValidateCode(SUBACK, b) {
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return codes.ErrProtocol
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}
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p.Payload = append(p.Payload, b)
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if bufr.Len() == 0 {
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return nil
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}
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}
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}
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