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publish.go
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publish.go
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// Copyright 2014, Shuhei Tanuma. All rights reserved.
// Use of this source code is governed by a MIT license
// that can be found in the LICENSE file.
package mqtt
import (
"bytes"
"encoding/binary"
"encoding/json"
"fmt"
"io"
)
type PublishMessage struct {
FixedHeader `json:"header"`
TopicName string `json:"topic_name"`
PacketIdentifier uint16 `json:"identifier"`
Payload []byte `json:"payload"`
Opaque interface{} `json:"-"`
}
func (self *PublishMessage) decode(reader io.Reader) error {
var length uint16
remaining := self.FixedHeader.RemainingLength
binary.Read(reader, binary.BigEndian, &length)
remaining -= 2
if remaining < 1 {
return fmt.Errorf("something wrong. (probably crouppted data?)")
}
buffer := make([]byte, remaining)
offset := 0
for offset < remaining {
if offset > remaining {
panic("something went to wrong(offset overs remianing length)")
}
i, err := reader.Read(buffer[offset:])
offset += i
if err != nil && offset < remaining {
// if we read whole size of message, ignore error at this time.
return err
}
}
if int(length) > len(buffer) {
return fmt.Errorf("publish length: %d, buffer: %d", length, len(buffer))
}
self.TopicName = string(buffer[0:length])
payload_offset := length
if self.FixedHeader.QosLevel > 0 {
binary.Read(bytes.NewReader(buffer[length:]), binary.BigEndian, &self.PacketIdentifier)
payload_offset += 2
}
self.Payload = buffer[payload_offset:]
return nil
}
func (self *PublishMessage) WriteTo(w io.Writer) (int64, error) {
var size uint16 = uint16(len(self.TopicName))
total := 2 + int(size)
if self.QosLevel > 0 {
total += 2
}
total += len(self.Payload)
header_len, e := self.FixedHeader.writeTo(total, w)
if e != nil {
return 0, e
}
total += int(size)
e = binary.Write(w, binary.BigEndian, size)
if e != nil {
return 0, e
}
w.Write([]byte(self.TopicName))
if self.QosLevel > 0 {
e = binary.Write(w, binary.BigEndian, self.PacketIdentifier)
}
if e != nil {
return 0, e
}
_, e = w.Write(self.Payload)
if e != nil {
return 0, e
}
return int64(int(total) + int(header_len)), nil
}
func (self *PublishMessage) String() string {
b, _ := json.Marshal(self)
return string(b)
}