mqtt-packet
===========
Encode and Decode MQTT 3.1.1, 5.0 packets the node way.
[](https://github.com/feross/standard)
* Installation
* Examples
* Packets
* API
* Contributing
* License & copyright
This library is tested with node v6, v8, v10, v12 and v14. The last version to support
older versions of node was mqtt-packet@4.1.2.
Installation
------------
```bash
npm install mqtt-packet --save
```
Examples
--------
### Generating
```js
const mqtt = require('mqtt-packet');
const object = {
cmd: 'publish',
retain: false,
qos: 0,
dup: false,
length: 10,
topic: 'test',
payload: 'test' // Can also be a Buffer
};
const opts = { protocolVersion: 4 }; // default is 4. Usually, opts is a connect packet
console.log(mqtt.generate(object))
// Prints:
//
//
//
// Which is the same as:
//
// Buffer.from([
// 48, 10, // Header (publish)
// 0, 4, // Topic length
// 116, 101, 115, 116, // Topic (test)
// 116, 101, 115, 116 // Payload (test)
// ])
```
### Parsing
```js
const mqtt = require('mqtt-packet');
const opts = { protocolVersion: 4 }; // default is 4. Usually, opts is a connect packet
const parser = mqtt.parser(opts);
// Synchronously emits all the parsed packets
parser.on('packet', packet => {
console.log(packet)
// Prints:
//
// {
// cmd: 'publish',
// retain: false,
// qos: 0,
// dup: false,
// length: 10,
// topic: 'test',
// payload:
// }
})
parser.parse(Buffer.from([
48, 10, // Header (publish)
0, 4, // Topic length
116, 101, 115, 116, // Topic (test)
116, 101, 115, 116 // Payload (test)
]))
// Returns the number of bytes left in the parser
```
API
---
* mqtt#generate()
* mqtt#writeToStream()
* mqtt#parser()
### mqtt.generate(object, [opts])
Generates a `Buffer` containing an MQTT packet.
The object must be one of the ones specified by the [packets](#packets)
section. Throws an `Error` if a packet cannot be generated.
### mqtt.writeToStream(object, stream, [opts])
Writes the mqtt packet defined by `object` to the given stream.
The object must be one of the ones specified by the [packets](#packets)
section. Emits an `Error` on the stream if a packet cannot be generated.
On node >= 0.12, this function automatically calls `cork()` on your stream,
and then it calls `uncork()` on the next tick.
By default cache for number buffers is enabled.
It creates a list of buffers for faster write. To disable cache set `mqtt.writeToStream.cacheNumbers = false`.
Should be set before any `writeToStream` calls.
### mqtt.parser([opts])
Returns a new `Parser` object. `Parser` inherits from `EventEmitter` and
will emit:
* `packet`, when a new packet is parsed, according to
[packets](#packets)
* `error`, if an error happens
#### Parser.parse(buffer)
Parses a given `Buffer` and emits synchronously all the MQTT packets that
are included. Returns the number of bytes left to parse.
If an error happens, an `error` event will be emitted, but no `packet` events
will be emitted after that. Calling `parse()` again clears the error and
previous buffer, as if you created a new `Parser`.
Packets
-------
This section describes the format of all packets emitted by the `Parser`
and that you can input to `generate`.
### Connect
```js
{
cmd: 'connect',
protocolId: 'MQTT', // Or 'MQIsdp' in MQTT 3.1 and 5.0
protocolVersion: 4, // Or 3 in MQTT 3.1, or 5 in MQTT 5.0
clean: true, // Can also be false
clientId: 'my-device',
keepalive: 0, // Seconds which can be any positive number, with 0 as the default setting
username: 'matteo',
password: Buffer.from('collina'), // Passwords are buffers
will: {
topic: 'mydevice/status',
payload: Buffer.from('dead'), // Payloads are buffers
properties: { // MQTT 5.0
willDelayInterval: 1234,
payloadFormatIndicator: false,
messageExpiryInterval: 4321,
contentType: 'test',
responseTopic: 'topic',
correlationData: Buffer.from([1, 2, 3, 4]),
userProperties: {
'test': 'test'
}
}
},
properties: { // MQTT 5.0 properties
sessionExpiryInterval: 1234,
receiveMaximum: 432,
maximumPacketSize: 100,
topicAliasMaximum: 456,
requestResponseInformation: true,
requestProblemInformation: true,
userProperties: {
'test': 'test'
},
authenticationMethod: 'test',
authenticationData: Buffer.from([1, 2, 3, 4])
}
}
```
If `protocolVersion` is 3, `clientId` is mandatory and `generate` will throw if
missing.
If `password` or `will.payload` are passed as strings, they will
automatically be converted into a `Buffer`.
### Connack
```js
{
cmd: 'connack',
returnCode: 0, // Or whatever else you see fit MQTT < 5.0
sessionPresent: false, // Can also be true.
reasonCode: 0, // reason code MQTT 5.0
properties: { // MQTT 5.0 properties
sessionExpiryInterval: 1234,
receiveMaximum: 432,
maximumQoS: 2,
retainAvailable: true,
maximumPacketSize: 100,
assignedClientIdentifier: 'test',
topicAliasMaximum: 456,
reasonString: 'test',
userProperties: {
'test': 'test'
},
wildcardSubscriptionAvailable: true,
subscriptionIdentifiersAvailable: true,
sharedSubscriptionAvailable: false,
serverKeepAlive: 1234,
responseInformation: 'test',
serverReference: 'test',
authenticationMethod: 'test',
authenticationData: Buffer.from([1, 2, 3, 4])
}
}
```
The only mandatory argument is `returnCode`, as `generate` will throw if
missing.
### Subscribe
```js
{
cmd: 'subscribe',
messageId: 42,
properties: { // MQTT 5.0 properties
subscriptionIdentifier: 145,
userProperties: {
test: 'test'
}
}
subscriptions: [{
topic: 'test',
qos: 0,
nl: false, // no Local MQTT 5.0 flag
rap: true, // Retain as Published MQTT 5.0 flag
rh: 1 // Retain Handling MQTT 5.0
}]
}
```
All properties are mandatory.
### Suback
```js
{
cmd: 'suback',
messageId: 42,
properties: { // MQTT 5.0 properties
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
granted: [0, 1, 2, 128]
}
```
All the granted qos __must__ be < 256, as they are encoded as UInt8.
All properties are mandatory.
### Unsubscribe
```js
{
cmd: 'unsubscribe',
messageId: 42,
properties: { // MQTT 5.0 properties
userProperties: {
'test': 'test'
}
}
unsubscriptions: [
'test',
'a/topic'
]
}
```
All properties are mandatory.
### Unsuback
```js
{
cmd: 'unsuback',
messageId: 42,
properties: { // MQTT 5.0 properties
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
All properties are mandatory.
### Publish
```js
{
cmd: 'publish',
messageId: 42,
qos: 2,
dup: false,
topic: 'test',
payload: Buffer.from('test'),
retain: false,
properties: { // optional properties MQTT 5.0
payloadFormatIndicator: true,
messageExpiryInterval: 4321,
topicAlias: 100,
responseTopic: 'topic',
correlationData: Buffer.from([1, 2, 3, 4]),
userProperties: {
'test': 'test'
},
subscriptionIdentifier: 120, // can be an Array in message from broker, if message included in few another subscriptions
contentType: 'test'
}
}
```
Only the `topic` property is mandatory.
Both `topic` and `payload` can be `Buffer` objects instead of strings.
`messageId` is mandatory for `qos > 0`.
### Puback
```js
{
cmd: 'puback',
messageId: 42,
reasonCode: 16, // only for MQTT 5.0
properties: { // MQTT 5.0 properties
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
The only mandatory property is `messageId`, as `generate` will throw if
missing.
### Pubrec
```js
{
cmd: 'pubrec',
messageId: 42,
reasonCode: 16, // only for MQTT 5.0
properties: { // properties MQTT 5.0
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
The only mandatory property is `messageId`, as `generate` will throw if
missing.
### Pubrel
```js
{
cmd: 'pubrel',
messageId: 42,
reasonCode: 16, // only for MQTT 5.0
properties: { // properties MQTT 5.0
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
The only mandatory property is `messageId`, as `generate` will throw if
missing.
### Pubcomp
```js
{
cmd: 'pubcomp',
messageId: 42,
reasonCode: 16, // only for MQTT 5.0
properties: { // properties MQTT 5.0
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
The only mandatory property is `messageId`, as `generate` will throw if
missing.
### Pingreq
```js
{
cmd: 'pingreq'
}
```
### Pingresp
```js
{
cmd: 'pingresp'
}
```
### Disconnect
```js
{
cmd: 'disconnect',
reasonCode: 0, // MQTT 5.0 code
properties: { // properties MQTT 5.0
sessionExpiryInterval: 145,
reasonString: 'test',
userProperties: {
'test': 'test'
},
serverReference: 'test'
}
}
```
### Auth
```js
{
cmd: 'auth',
reasonCode: 0, // MQTT 5.0 code
properties: { // properties MQTT 5.0
authenticationMethod: 'test',
authenticationData: Buffer.from([0, 1, 2, 3]),
reasonString: 'test',
userProperties: {
'test': 'test'
}
}
}
```
Contributing
------------
mqtt-packet is an **OPEN Open Source Project**. This means that:
> Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.
See the [CONTRIBUTING.md](https://github.com/mqttjs/mqtt-packet/blob/master/CONTRIBUTING.md) file for more details.
### Contributors
mqtt-packet is only possible due to the excellent work of the following contributors:
License
-------
MIT