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package packets
import (
"bytes"
"fmt"
"github.com/pborman/uuid"
"io"
)
//PublishPacket is an internal representation of the fields of the
//Publish MQTT packet
type PublishPacket struct {
FixedHeader
TopicName string
MessageID uint16
Payload []byte
uuid uuid.UUID
}
func (p *PublishPacket) String() string {
str := fmt.Sprintf("%s\n", p.FixedHeader)
str += fmt.Sprintf("topicName: %s MessageID: %d\n", p.TopicName, p.MessageID)
str += fmt.Sprintf("payload: %s\n", string(p.Payload))
return str
}
func (p *PublishPacket) Write(w io.Writer) error {
var body bytes.Buffer
var err error
body.Write(encodeString(p.TopicName))
if p.Qos > 0 {
body.Write(encodeUint16(p.MessageID))
}
p.FixedHeader.RemainingLength = body.Len() + len(p.Payload)
packet := p.FixedHeader.pack()
packet.Write(body.Bytes())
packet.Write(p.Payload)
_, err = w.Write(packet.Bytes())
return err
}
//Unpack decodes the details of a ControlPacket after the fixed
//header has been read
func (p *PublishPacket) Unpack(b io.Reader) {
var payloadLength = p.FixedHeader.RemainingLength
p.TopicName = decodeString(b)
if p.Qos > 0 {
p.MessageID = decodeUint16(b)
payloadLength -= len(p.TopicName) + 4
} else {
payloadLength -= len(p.TopicName) + 2
}
p.Payload = make([]byte, payloadLength)
b.Read(p.Payload)
}
//Copy creates a new PublishPacket with the same topic and payload
//but an empty fixed header, useful for when you want to deliver
//a message with different properties such as Qos but the same
//content
func (p *PublishPacket) Copy() *PublishPacket {
newP := NewControlPacket(Publish).(*PublishPacket)
newP.TopicName = p.TopicName
newP.Payload = p.Payload
return newP
}
//Details returns a Details struct containing the Qos and
//MessageID of this ControlPacket
func (p *PublishPacket) Details() Details {
return Details{Qos: p.Qos, MessageID: p.MessageID}
}
//UUID returns the unique ID assigned to the ControlPacket when
//it was originally received. Note: this is not related to the
//MessageID field for MQTT packets
func (p *PublishPacket) UUID() uuid.UUID {
return p.uuid
}
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