70 lines
1.5 KiB
Go
70 lines
1.5 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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)
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// SubscribePacket is an internal representation of the fields of the
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// Subscribe MQTT packet
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type SubscribePacket struct {
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FixedHeader
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MessageID uint16
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Topics []string
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Qoss []byte
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}
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func (s *SubscribePacket) String() string {
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return fmt.Sprintf("%s MessageID: %d topics: %s", s.FixedHeader, s.MessageID, s.Topics)
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}
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func (s *SubscribePacket) Write(w io.Writer) error {
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var body bytes.Buffer
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var err error
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body.Write(encodeUint16(s.MessageID))
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for i, topic := range s.Topics {
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body.Write(encodeString(topic))
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body.WriteByte(s.Qoss[i])
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}
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s.FixedHeader.RemainingLength = body.Len()
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packet := s.FixedHeader.pack()
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packet.Write(body.Bytes())
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_, err = packet.WriteTo(w)
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return err
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}
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// Unpack decodes the details of a ControlPacket after the fixed
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// header has been read
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func (s *SubscribePacket) Unpack(b io.Reader) error {
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var err error
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s.MessageID, err = decodeUint16(b)
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if err != nil {
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return err
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}
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payloadLength := s.FixedHeader.RemainingLength - 2
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for payloadLength > 0 {
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topic, err := decodeString(b)
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if err != nil {
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return err
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}
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s.Topics = append(s.Topics, topic)
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qos, err := decodeByte(b)
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if err != nil {
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return err
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}
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s.Qoss = append(s.Qoss, qos)
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payloadLength -= 2 + len(topic) + 1 // 2 bytes of string length, plus string, plus 1 byte for Qos
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}
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return nil
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}
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// Details returns a Details struct containing the Qos and
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// MessageID of this ControlPacket
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func (s *SubscribePacket) Details() Details {
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return Details{Qos: 1, MessageID: s.MessageID}
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}
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