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JOYnr JavaScript libjoynr-js
'use strict'
var protocol = require('./constants')
var Buffer = require('safe-buffer').Buffer
var empty = Buffer.allocUnsafe(0)
var zeroBuf = Buffer.from([0])
var numbers = require('./numbers')
var nextTick = require('process-nextick-args').nextTick
var numCache = numbers.cache
var generateNumber = numbers.generateNumber
var generateCache = numbers.generateCache
var writeNumber = writeNumberCached
var toGenerate = true
function generate (packet, stream) {
if (stream.cork) {
stream.cork()
nextTick(uncork, stream)
}
if (toGenerate) {
toGenerate = false
generateCache()
}
switch (packet.cmd) {
case 'connect':
return connect(packet, stream)
case 'connack':
return connack(packet, stream)
case 'publish':
return publish(packet, stream)
case 'puback':
case 'pubrec':
case 'pubrel':
case 'pubcomp':
case 'unsuback':
return confirmation(packet, stream)
case 'subscribe':
return subscribe(packet, stream)
case 'suback':
return suback(packet, stream)
case 'unsubscribe':
return unsubscribe(packet, stream)
case 'pingreq':
case 'pingresp':
case 'disconnect':
return emptyPacket(packet, stream)
default:
stream.emit('error', new Error('Unknown command'))
return false
}
}
/**
* Controls numbers cache.
* Set to "false" to allocate buffers on-the-flight instead of pre-generated cache
*/
Object.defineProperty(generate, 'cacheNumbers', {
get: function () {
return writeNumber === writeNumberCached
},
set: function (value) {
if (value) {
if (!numCache || Object.keys(numCache).length === 0) toGenerate = true
writeNumber = writeNumberCached
} else {
toGenerate = false
writeNumber = writeNumberGenerated
}
}
})
function uncork (stream) {
stream.uncork()
}
function connect (opts, stream) {
var settings = opts || {}
var protocolId = settings.protocolId || 'MQTT'
var protocolVersion = settings.protocolVersion || 4
var will = settings.will
var clean = settings.clean
var keepalive = settings.keepalive || 0
var clientId = settings.clientId || ''
var username = settings.username
var password = settings.password
if (clean === undefined) clean = true
var length = 0
// Must be a string and non-falsy
if (!protocolId ||
(typeof protocolId !== 'string' && !Buffer.isBuffer(protocolId))) {
stream.emit('error', new Error('Invalid protocolId'))
return false
} else length += protocolId.length + 2
// Must be 3 or 4
if (protocolVersion !== 3 && protocolVersion !== 4) {
stream.emit('error', new Error('Invalid protocol version'))
return false
} else length += 1
// ClientId might be omitted in 3.1.1, but only if cleanSession is set to 1
if ((typeof clientId === 'string' || Buffer.isBuffer(clientId)) &&
(clientId || protocolVersion === 4) && (clientId || clean)) {
length += clientId.length + 2
} else {
if (protocolVersion < 4) {
stream.emit('error', new Error('clientId must be supplied before 3.1.1'))
return false
}
if ((clean * 1) === 0) {
stream.emit('error', new Error('clientId must be given if cleanSession set to 0'))
return false
}
}
// Must be a two byte number
if (typeof keepalive !== 'number' ||
keepalive < 0 ||
keepalive > 65535 ||
keepalive % 1 !== 0) {
stream.emit('error', new Error('Invalid keepalive'))
return false
} else length += 2
// Connect flags
length += 1
// If will exists...
if (will) {
// It must be an object
if (typeof will !== 'object') {
stream.emit('error', new Error('Invalid will'))
return false
}
// It must have topic typeof string
if (!will.topic || typeof will.topic !== 'string') {
stream.emit('error', new Error('Invalid will topic'))
return false
} else {
length += Buffer.byteLength(will.topic) + 2
}
// Payload
if (will.payload && will.payload) {
if (will.payload.length >= 0) {
if (typeof will.payload === 'string') {
length += Buffer.byteLength(will.payload) + 2
} else {
length += will.payload.length + 2
}
} else {
stream.emit('error', new Error('Invalid will payload'))
return false
}
} else {
length += 2
}
}
// Username
var providedUsername = false
if (username != null) {
if (isStringOrBuffer(username)) {
providedUsername = true
length += Buffer.byteLength(username) + 2
} else {
stream.emit('error', new Error('Invalid username'))
return false
}
}
// Password
if (password != null) {
if (!providedUsername) {
stream.emit('error', new Error('Username is required to use password'))
return false
}
if (isStringOrBuffer(password)) {
length += byteLength(password) + 2
} else {
stream.emit('error', new Error('Invalid password'))
return false
}
}
// Generate header
stream.write(protocol.CONNECT_HEADER)
// Generate length
writeLength(stream, length)
// Generate protocol ID
writeStringOrBuffer(stream, protocolId)
stream.write(
protocolVersion === 4 ? protocol.VERSION4 : protocol.VERSION3
)
// Connect flags
var flags = 0
flags |= (username != null) ? protocol.USERNAME_MASK : 0
flags |= (password != null) ? protocol.PASSWORD_MASK : 0
flags |= (will && will.retain) ? protocol.WILL_RETAIN_MASK : 0
flags |= (will && will.qos) ? will.qos << protocol.WILL_QOS_SHIFT : 0
flags |= will ? protocol.WILL_FLAG_MASK : 0
flags |= clean ? protocol.CLEAN_SESSION_MASK : 0
stream.write(Buffer.from([flags]))
// Keepalive
writeNumber(stream, keepalive)
// Client ID
writeStringOrBuffer(stream, clientId)
// Will
if (will) {
writeString(stream, will.topic)
writeStringOrBuffer(stream, will.payload)
}
// Username and password
if (username != null) {
writeStringOrBuffer(stream, username)
}
if (password != null) {
writeStringOrBuffer(stream, password)
}
// This is a small packet that happens only once on a stream
// We assume the stream is always free to receive more data after this
return true
}
function connack (opts, stream) {
var settings = opts || {}
var rc = settings.returnCode
// Check return code
if (typeof rc !== 'number') {
stream.emit('error', new Error('Invalid return code'))
return false
}
stream.write(protocol.CONNACK_HEADER)
writeLength(stream, 2)
stream.write(opts.sessionPresent ? protocol.SESSIONPRESENT_HEADER : zeroBuf)
return stream.write(Buffer.from([rc]))
}
function publish (opts, stream) {
var settings = opts || {}
var qos = settings.qos || 0
var retain = settings.retain ? protocol.RETAIN_MASK : 0
var topic = settings.topic
var payload = settings.payload || empty
var id = settings.messageId
var length = 0
// Topic must be a non-empty string or Buffer
if (typeof topic === 'string') length += Buffer.byteLength(topic) + 2
else if (Buffer.isBuffer(topic)) length += topic.length + 2
else {
stream.emit('error', new Error('Invalid topic'))
return false
}
// Get the payload length
if (!Buffer.isBuffer(payload)) length += Buffer.byteLength(payload)
else length += payload.length
// Message ID must a number if qos > 0
if (qos && typeof id !== 'number') {
stream.emit('error', new Error('Invalid messageId'))
return false
} else if (qos) length += 2
// Header
stream.write(protocol.PUBLISH_HEADER[qos][opts.dup ? 1 : 0][retain ? 1 : 0])
// Remaining length
writeLength(stream, length)
// Topic
writeNumber(stream, byteLength(topic))
stream.write(topic)
// Message ID
if (qos > 0) writeNumber(stream, id)
// Payload
return stream.write(payload)
}
/* Puback, pubrec, pubrel and pubcomp */
function confirmation (opts, stream) {
var settings = opts || {}
var type = settings.cmd || 'puback'
var id = settings.messageId
var dup = (settings.dup && type === 'pubrel') ? protocol.DUP_MASK : 0
var qos = 0
if (type === 'pubrel') qos = 1
// Check message ID
if (typeof id !== 'number') {
stream.emit('error', new Error('Invalid messageId'))
return false
}
// Header
stream.write(protocol.ACKS[type][qos][dup][0])
// Length
writeLength(stream, 2)
// Message ID
return writeNumber(stream, id)
}
function subscribe (opts, stream) {
var settings = opts || {}
var dup = settings.dup ? protocol.DUP_MASK : 0
var id = settings.messageId
var subs = settings.subscriptions
var length = 0
// Check message ID
if (typeof id !== 'number') {
stream.emit('error', new Error('Invalid messageId'))
return false
} else length += 2
// Check subscriptions
if (typeof subs === 'object' && subs.length) {
for (var i = 0; i < subs.length; i += 1) {
var itopic = subs[i].topic
var iqos = subs[i].qos
if (typeof itopic !== 'string') {
stream.emit('error', new Error('Invalid subscriptions - invalid topic'))
return false
}
if (typeof iqos !== 'number') {
stream.emit('error', new Error('Invalid subscriptions - invalid qos'))
return false
}
length += Buffer.byteLength(itopic) + 2 + 1
}
} else {
stream.emit('error', new Error('Invalid subscriptions'))
return false
}
// Generate header
stream.write(protocol.SUBSCRIBE_HEADER[1][dup ? 1 : 0][0])
// Generate length
writeLength(stream, length)
// Generate message ID
writeNumber(stream, id)
var result = true
// Generate subs
for (var j = 0; j < subs.length; j++) {
var sub = subs[j]
var jtopic = sub.topic
var jqos = sub.qos
// Write topic string
writeString(stream, jtopic)
// Write qos
result = stream.write(protocol.QOS[jqos])
}
return result
}
function suback (opts, stream) {
var settings = opts || {}
var id = settings.messageId
var granted = settings.granted
var length = 0
// Check message ID
if (typeof id !== 'number') {
stream.emit('error', new Error('Invalid messageId'))
return false
} else length += 2
// Check granted qos vector
if (typeof granted === 'object' && granted.length) {
for (var i = 0; i < granted.length; i += 1) {
if (typeof granted[i] !== 'number') {
stream.emit('error', new Error('Invalid qos vector'))
return false
}
length += 1
}
} else {
stream.emit('error', new Error('Invalid qos vector'))
return false
}
// header
stream.write(protocol.SUBACK_HEADER)
// Length
writeLength(stream, length)
// Message ID
writeNumber(stream, id)
return stream.write(Buffer.from(granted))
}
function unsubscribe (opts, stream) {
var settings = opts || {}
var id = settings.messageId
var dup = settings.dup ? protocol.DUP_MASK : 0
var unsubs = settings.unsubscriptions
var length = 0
// Check message ID
if (typeof id !== 'number') {
stream.emit('error', new Error('Invalid messageId'))
return false
} else {
length += 2
}
// Check unsubs
if (typeof unsubs === 'object' && unsubs.length) {
for (var i = 0; i < unsubs.length; i += 1) {
if (typeof unsubs[i] !== 'string') {
stream.emit('error', new Error('Invalid unsubscriptions'))
return false
}
length += Buffer.byteLength(unsubs[i]) + 2
}
} else {
stream.emit('error', new Error('Invalid unsubscriptions'))
return false
}
// Header
stream.write(protocol.UNSUBSCRIBE_HEADER[1][dup ? 1 : 0][0])
// Length
writeLength(stream, length)
// Message ID
writeNumber(stream, id)
// Unsubs
var result = true
for (var j = 0; j < unsubs.length; j++) {
result = writeString(stream, unsubs[j])
}
return result
}
function emptyPacket (opts, stream) {
return stream.write(protocol.EMPTY[opts.cmd])
}
/**
* calcLengthLength - calculate the length of the remaining
* length field
*
* @api private
*/
function calcLengthLength (length) {
if (length >= 0 && length < 128) return 1
else if (length >= 128 && length < 16384) return 2
else if (length >= 16384 && length < 2097152) return 3
else if (length >= 2097152 && length < 268435456) return 4
else return 0
}
function genBufLength (length) {
var digit = 0
var pos = 0
var buffer = Buffer.allocUnsafe(calcLengthLength(length))
do {
digit = length % 128 | 0
length = length / 128 | 0
if (length > 0) digit = digit | 0x80
buffer.writeUInt8(digit, pos++)
} while (length > 0)
return buffer
}
/**
* writeLength - write an MQTT style length field to the buffer
*
* @param buffer - destination
* @param pos - offset
* @param length - length (>0)
* @returns number of bytes written
*
* @api private
*/
var lengthCache = {}
function writeLength (stream, length) {
var buffer = lengthCache[length]
if (!buffer) {
buffer = genBufLength(length)
if (length < 16384) lengthCache[length] = buffer
}
stream.write(buffer)
}
/**
* writeString - write a utf8 string to the buffer
*
* @param buffer - destination
* @param pos - offset
* @param string - string to write
* @return number of bytes written
*
* @api private
*/
function writeString (stream, string) {
var strlen = Buffer.byteLength(string)
writeNumber(stream, strlen)
stream.write(string, 'utf8')
}
/**
* writeNumber - write a two byte number to the buffer
*
* @param buffer - destination
* @param pos - offset
* @param number - number to write
* @return number of bytes written
*
* @api private
*/
function writeNumberCached (stream, number) {
return stream.write(numCache[number])
}
function writeNumberGenerated (stream, number) {
return stream.write(generateNumber(number))
}
/**
* writeStringOrBuffer - write a String or Buffer with the its length prefix
*
* @param buffer - destination
* @param pos - offset
* @param toWrite - String or Buffer
* @return number of bytes written
*/
function writeStringOrBuffer (stream, toWrite) {
if (typeof toWrite === 'string') {
writeString(stream, toWrite)
} else if (toWrite) {
writeNumber(stream, toWrite.length)
stream.write(toWrite)
} else writeNumber(stream, 0)
}
function byteLength (bufOrString) {
if (!bufOrString) return 0
else if (bufOrString instanceof Buffer) return bufOrString.length
else return Buffer.byteLength(bufOrString)
}
function isStringOrBuffer (field) {
return typeof field === 'string' || field instanceof Buffer
}
module.exports = generate
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