iot_server/internal/pkg/packets/pubrel.go

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2023-08-28 06:49:44 +00:00
package packets
import (
"bytes"
"fmt"
"io"
"github.com/winc-link/hummingbird/internal/pkg/codes"
)
// Pubrel represents the MQTT Pubrel packet
type Pubrel struct {
FixHeader *FixHeader
PacketID PacketID
// V5
Code codes.Code
Properties *Properties
}
func (p *Pubrel) String() string {
return fmt.Sprintf("Pubrel, Code: %v, Pid: %v, Properties: %s", p.Code, p.PacketID, p.Properties)
}
// NewPubrelPacket returns a Pubrel instance by the given FixHeader and io.Reader.
func NewPubrelPacket(fh *FixHeader, r io.Reader) (*Pubrel, error) {
p := &Pubrel{FixHeader: fh}
err := p.Unpack(r)
if err != nil {
return nil, err
}
return p, nil
}
// NewPubcomp returns the Pubcomp struct related to the Pubrel struct in QoS 2.
func (p *Pubrel) NewPubcomp() *Pubcomp {
pub := &Pubcomp{FixHeader: &FixHeader{PacketType: PUBCOMP, Flags: FlagReserved, RemainLength: 2}}
pub.PacketID = p.PacketID
return pub
}
// Pack encodes the packet struct into bytes and writes it into io.Writer.
func (p *Pubrel) Pack(w io.Writer) error {
p.FixHeader = &FixHeader{PacketType: PUBREL, Flags: FlagPubrel}
bufw := &bytes.Buffer{}
writeUint16(bufw, p.PacketID)
if p.Code != codes.Success || p.Properties != nil {
bufw.WriteByte(p.Code)
p.Properties.Pack(bufw, PUBREL)
}
p.FixHeader.RemainLength = bufw.Len()
err := p.FixHeader.Pack(w)
if err != nil {
return err
}
_, err = bufw.WriteTo(w)
return err
}
// Unpack read the packet bytes from io.Reader and decodes it into the packet struct.
func (p *Pubrel) Unpack(r io.Reader) error {
restBuffer := make([]byte, p.FixHeader.RemainLength)
_, err := io.ReadFull(r, restBuffer)
if err != nil {
return codes.ErrMalformed
}
bufr := bytes.NewBuffer(restBuffer)
p.PacketID, err = readUint16(bufr)
if err != nil {
return err
}
if p.FixHeader.RemainLength == 2 {
p.Code = codes.Success
return nil
}
p.Properties = &Properties{}
if p.Code, err = bufr.ReadByte(); err != nil {
return err
}
if !ValidateCode(PUBREL, p.Code) {
return codes.ErrProtocol
}
return p.Properties.Unpack(bufr, PUBREL)
}