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/*
* Copyright (c) 2021 IBM Corp and others.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v2.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* https://www.eclipse.org/legal/epl-2.0/
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Allan Stockdill-Mander
*/
package packets
import (
"bytes"
"fmt"
"io"
)
// SubscribePacket is an internal representation of the fields of the
// Subscribe MQTT packet
type SubscribePacket struct {
FixedHeader
MessageID uint16
Topics []string
Qoss []byte
}
func (s *SubscribePacket) String() string {
return fmt.Sprintf("%s MessageID: %d topics: %s", s.FixedHeader, s.MessageID, s.Topics)
}
func (s *SubscribePacket) Write(w io.Writer) error {
var body bytes.Buffer
var err error
body.Write(encodeUint16(s.MessageID))
for i, topic := range s.Topics {
body.Write(encodeString(topic))
body.WriteByte(s.Qoss[i])
}
s.FixedHeader.RemainingLength = body.Len()
packet := s.FixedHeader.pack()
packet.Write(body.Bytes())
_, err = packet.WriteTo(w)
return err
}
// Unpack decodes the details of a ControlPacket after the fixed
// header has been read
func (s *SubscribePacket) Unpack(b io.Reader) error {
var err error
s.MessageID, err = decodeUint16(b)
if err != nil {
return err
}
payloadLength := s.FixedHeader.RemainingLength - 2
for payloadLength > 0 {
topic, err := decodeString(b)
if err != nil {
return err
}
s.Topics = append(s.Topics, topic)
qos, err := decodeByte(b)
if err != nil {
return err
}
s.Qoss = append(s.Qoss, qos)
payloadLength -= 2 + len(topic) + 1 // 2 bytes of string length, plus string, plus 1 byte for Qos
}
return nil
}
// Details returns a Details struct containing the Qos and
// MessageID of this ControlPacket
func (s *SubscribePacket) Details() Details {
return Details{Qos: 1, MessageID: s.MessageID}
}
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