refactored _send in socket class

added authentifcation with default being a token
attach any passed client name to server side client socket
master
David Kebler 2019-08-23 15:48:39 -07:00
parent 375790bfc4
commit 3299e9125e
4 changed files with 300 additions and 185 deletions

View File

@ -5,29 +5,51 @@ import btc from 'better-try-catch'
const client= new Consumer({path:true, name:'example-consumer', initTimeout:30 })
// This is your client handler object waiting on a message to do something
const process = async (packet) => {
console.log('packet being processed at socket')
async function processor (packet) {
// console.log('packet being processed at socket', packet)
if (packet.cmd) {
if (this[packet.cmd]) return await this[packet.cmd](packet)
else return {error: 'command has no processing function', packet: packet }
} return {error: 'no command in packet', packet: packet }
else {
console.log('no processing function for command', packet.cmd)
return {error: 'command has no processing function', packet: packet }
}
}
console.log('no command in packet', packet)
return {error: 'no command in packet', packet: packet }
}
client.pushed = async (packet) => {
client.registerPacketProcessor(processor)
client.reply = (packet) => {
return new Promise(resolve => {
console.log('pushed packet/n',packet)
console.log('generic reply command from server\n',packet.data)
resolve()
})
}
client.registerPacketProcessor(process)
client.onconnect = (packet) => {
return new Promise(resolve => {
console.log('on connect server sent command processed here\n',packet.data)
resolve()
})
}
client.pushed = (packet) => {
return new Promise(resolve => {
console.log('pushed packet\n',packet.status)
resolve()
})
}
client.on('connection', event => {
console.log('============ connection update ============')
console.log(event.id)
console.log(event.msg)
console.log(`${event.ready ? 'Consumer is connected' : 'Consumer is disconnected'}`)
console.log(`Consumer is ${event.connected ? 'connected' : 'disconnected'}`)
console.log(`Authenticated? ${event.authenticated || false}`)
console.log('======================================')
})
@ -39,11 +61,11 @@ client.on('connection', event => {
if (err) {
console.log('error', err)
} else {
console.log('ready now?',client.ready)
console.log('connect reponse',res)
console.log(res)
let packet = {name: 'client', cmd:'doit', data:'sent by client'}
console.log('sending packet ', packet)
console.log('=========\n',await client.send(packet))
console.log('=============sending a test packet=========\n', packet)
console.log('can also await relay of any send too for processing in sync manner\n',await client.send(packet))
console.log('===============')
}
})().catch(err => {

View File

@ -14,18 +14,11 @@ class Test extends Socket {
super(opts)
}
async _packetProcess(packet) {
console.log('packet being processed at socket')
if (packet.cmd) return await this[packet.cmd](packet.data,packet.name)
return {error: 'no command in packet', packet: packet }
}
async doit(data,name) {
async doit(packet) {
return new Promise(resolve => {
let res = {}
console.log('data sent to doit = ', data)
console.log('command doit sent with data = ', packet.data)
res.status ='success'
res.name = name
res.cmd = 'reply'
res.data = 'this would be response data from socket doit function'
resolve(res)
@ -34,7 +27,6 @@ class Test extends Socket {
}
// const options = {
// tls: TLS,
// key: await fs.readFile(TLS_KEY_PATH),
@ -45,13 +37,26 @@ class Test extends Socket {
// // ca: [ fs.readFileSync('client-cert.pem') ]
// }
let options = {path:true, conPacket:{onconnect:'this is a packet sent to consumer as soon as it connects'}}
// let test = new Test()
let options = {path:true, tokens:['test'], conPacket:{cmd:'onconnect', data:'this is a packet data sent consumer after handshake/authentification'}}
let test = new Test(options)
;
async function processor (packet) {
// console.log('packet being processed at socket', packet)
if (packet.cmd) {
if (this[packet.cmd]) return await this[packet.cmd](packet)
else {
console.log('no processing function for command', packet.cmd)
return {error: 'command has no processing function', packet: packet }
}
}
console.log('no command in packet', packet)
return {error: 'no command in packet', packet: packet }
}
test.registerPacketProcessor(processor)
;
(async () => {
// TODO dynamic import
// if(TLS_KEY_PATH && TLS_CRT_PATH && TLS) {
@ -63,10 +68,20 @@ let test = new Test(options)
await test.create()
let count = 0
setInterval( () => {
count++
test.push({cmd:'pushed', count:count, status:'some pushed data'})
},3000)
// const push = setInterval( () => {
// count++
// test.push({cmd:'pushed', count:count, status:`some pushed data ${count}`})
// if (count >3) {
// clearInterval(push)
// test.push({cmd:'pushed',status:'now will simulate server going offline by stopping to send pingfor 10 seconds'})
// test.disablePing()
// setTimeout( () => {
// test.enablePing()
// },10000)
//
// }
// },3000)
// setTimeout( () => {
// console.log('closing server')

View File

@ -49,9 +49,10 @@ class SocketConsumer extends Socket {
// default is keepAlive true, must set to false to explicitly disable
// if keepAlive is true then consumer will also be reconnecting consumer
this.initTimeout = opts.initTimeout * 1000 || 60000
this.retryWait = opts.retryWait * 1000 || 3000
this.retryWait = opts.retryWait * 1000 || 5000
this.keepAlive = 'keepAlive' in opts ? opts.keepAlive : true
this._ready = false
this._connected = false
this._authenticated = false
this.stream = new JsonStream()
// bind to class for other class functions
this.connect = this.connect.bind(this)
@ -60,10 +61,10 @@ class SocketConsumer extends Socket {
this._conAttempt = 1
this._aborted = false
this._reconnect = false
// this._write = this._write.bind(this)
// this._packetProcess = this._packetProcess.bind(this)
}
get ready() { return this._ready}
get connected() { return this._connected}
async connect() {
return new Promise((resolve, reject) => {
@ -74,33 +75,46 @@ class SocketConsumer extends Socket {
log.debug('first connnect attempt for', this.opts.name)
this.emit('connection',{msg:'attempting initial connection', id:this.id, opts:this.opts, ready:false})
let initTimeout = setTimeout(() => {
this.emit('connection',{msg:'initial connection timed out', id:this.id, timeout:this.initTimeout, wait:this.retryWait, opts:this.opts, ready:false})
this.removeAllListeners()
log.fatal({method:'connect', line:69, opts: this.opts, msg:`unable to initially connect to ${this.opts.name} in ${this.initTimeout/1000} secs no more attempts!`})
this.stream.removeAllListeners()
this.destroy()
reject({ opts: this.opts, msg: `unable to connect initially to socket server in ${this.initTimeout/1000} secs, giving up no more attempts`})
let initTimeout = {}
if (this.initTimeout > 499) {
initTimeout = setTimeout(() => {
this.emit('connection',{msg:'initial connection timed out', id:this.id, timeout:this.initTimeout, wait:this.retryWait, opts:this.opts, ready:false})
this.removeAllListeners()
log.fatal({method:'connect', line:69, opts: this.opts, msg:`unable to initially connect to ${this.opts.name} in ${this.initTimeout/1000} secs no more attempts!`})
this.stream.removeAllListeners()
this.destroy()
reject({ opts: this.opts, msg: `unable to connect initially to socket server in ${this.initTimeout/1000} secs, giving up no more attempts`})
}
, this.initTimeout)
}
, this.initTimeout)
const initialHandshake = async (packet) => {
if (packet._handshake) {
log.debug({method:'connect', line:87, msg:'handshake received ready for communication'})
this.stream.removeAllListeners('message')
this.removeListener('error',initialErrorHandler)
clearTimeout(initTimeout)
this._listen() // setup for active connection
this._ready = true
this.emit('connection',{msg:'initial connection succesfull', id:this.id, opts:this.opts, ready:true})
resolve('initial connection successful')
this._connected = true
let authPacket = this._authenticate()
authPacket._authenticate = true
authPacket.clientName = this.id
let res = (await this._authenticateSend(authPacket)) || {}
console.log('auth response', res)
// if ((await this.send(authPacket)).authenticated) authenticated()
if (!res.authenticated) reject('unable to authenticate')
else {
this._authenticated = res.authenticated
this.removeListener('error',initialErrorHandler)
this._listen() // setup for active connection
log.info({method:'connect', line:87, msg:'initial connect/authentication complete ready for communication'})
this.emit('connection',{msg:'authentication succesfull', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected})
resolve('initial connection successful')
}
}
}
const initialConnectHandler = async () => {
this.on('data', this.stream.onData)
this.stream.on('message', initialHandshake.bind(this))
this.stream.once('message', initialHandshake.bind(this))
log.debug({method:'connect', line:113, msg:'connected waiting for socket ready handshake'})
}
@ -120,7 +134,10 @@ class SocketConsumer extends Socket {
async send(ipacket) {
return new Promise(async resolve => {
if (!this._ready) resolve({ error: 'socket consumer not connected, aborting send' })
if (!this._connected) {
resolve({ error: 'socket consumer not connected, aborting send' })
return
}
let packet = Object.assign({}, ipacket) // need to avoid mutuation for different consumers using same packet instance
setTimeout(() => {resolve({ error: 'no response from socket in 10sec' })}, 10000)
packet._header = {
@ -136,7 +153,9 @@ class SocketConsumer extends Socket {
if (err)
resolve({error: 'unable to serialize packet for sending',packet: packet})
await this.__write(res)
console.log(packet._header)
this.once(packet._header.id, async function(reply) {
console.log('returning response', reply)
let res = await this._packetProcess(reply)
if (!res) { // if packetProcess was not promise
res = reply
@ -154,6 +173,26 @@ class SocketConsumer extends Socket {
}
// PRIVATE METHODS
_authenticate () {
return { token:'test'}
}
async _authenticateSend (authPacket) {
return new Promise(async resolve => {
setTimeout(() => {resolve({ error: 'no response from socket in 10sec' })}, 10000)
let [err, res] = await btc(this.stream.serialize)(authPacket)
if (err)
resolve({error: 'unable to serialize packet for sending',packet: authPacket})
this.stream.on('message',(res) => {
this.stream.removeAllListeners('message')
resolve(res)
})
await this.__write(res)
})
}
// set up incoming message listening and error/reonnect handling
async _listen() {
@ -161,43 +200,46 @@ class SocketConsumer extends Socket {
const reconnectHandler = () => {
this.stream.once('message', handshake.bind(this))
log.debug({method:'connect', line:113, msg:'connected waiting for socket ready handshake'})
this.emit('connection',{msg:'attemping reconnect', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected})
}
const handshake = async (packet) => {
if (packet._handshake) {
log.debug({method:'connect', line:87, msg:'handshake received ready for communication'})
this.stream.on('message', messageProcess.bind(this))
if (this.keepAlive) { // only attempt reconnect if keepAlive is set which it is by default
this.on('ping',pingHandler)
this.setKeepAlive(this.keepAlive,3000) // keep connection alive unless disabled
this._connected = true
let authPacket = this._authenticate()
authPacket._authenticate = true
authPacket.clientName = this.id
let res = (await this._authenticateSend(authPacket)) || {}
if (!res.authenticated) {
this.emit('connection',{msg:'authentification failed', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected, res:res})
}
else {
this._authenticated = res.authenticated
log.info({method:'connect', line:87, msg:'initial connect/authentication complete ready for communication'})
this.emit('connection',{msg:'authentication successful', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected})
if (this.keepAlive) { // only attempt reconnect if keepAlive is set which it is by default
this.on('ping',pingHandler)
this.setKeepAlive(this.keepAlive,3000) // keep connection alive unless disabled
}
this.stream.on('message', messageHandler.bind(this)) // reset default message handler
this.emit('connection',{msg:'reconnected', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected})
}
this._ready = true
this.emit('connection','reconnected')
}
}
const errorHandler = async (err) => {
log.debug({msg:'connection error emitted ', error:err})
this._ready = false
if (err.code !== 'EISCONN') {
this.emit('connection', err)
log.debug({ method:'connect', line:130, error: err.code, msg:`connect error ${err.code}, attempting reconnect after ${this.retryWait/1000} secs`})
await pause(this.retryWait)
this.stream.removeAllListeners('message') // remove regular message handler in prep for reconnect
this.removeAllListeners('connect')
this.once('connect',reconnectHandler)
super.connect(this.opts)
}
else {
this._ready = true
this.emit('connection','reconnected')
log.error({method:'connect', line:69, msg:'reconnected to socket, ready to go again'})
}
}
async function messageProcess(packet) {
log.debug('incoming packet from socket sever',packet)
this.emit(packet._header.id, packet)
this._connected = false
this._authenticated = false
this.emit('connection',{msg:'connection(socket) error', id:this.id, opts:this.opts, authenticated:this._authenticated, connected:this._connected})
log.debug({ method:'connect', line:130, error: err.code, msg:`connect error ${err.code}, attempting reconnect after ${this.retryWait/1000} secs`})
await pause(this.retryWait)
this.stream.removeAllListeners('message') // remove regular message handler in prep for reconnect
this.removeAllListeners('connect')
this.removeAllListeners('ping')
this.once('connect',reconnectHandler)
super.connect(this.opts)
}
const pushHandler = async (packet) => {
@ -212,7 +254,7 @@ class SocketConsumer extends Socket {
const pingHandler = async (packet) => {
clearTimeout(pingTimeout)
log.info({method:'connect', line:191, msg:'received ping, restting timeout'})
log.debug({method:'connect', line:191, msg:'received ping, restting timeout'})
this._pingTimeout= packet.pingInterval + 1000
monitorPing.call(this)
}
@ -222,14 +264,20 @@ class SocketConsumer extends Socket {
pingTimeout = setTimeout( () => {
log.error({method:'connect', line:142, msg:'socket (server) not availabe'})
this.removeAllListeners('ping')
this._ready = false
this._connected = false
this.emit('error', { code: 'PING-FAILED' })
},this._pingTimeout)
}
// general handler
function messageHandler(packet) {
log.debug('incoming packet from socket sever',packet)
this.emit(packet._header.id, packet)
}
// Start Message Listening and Error/Reconnect Handling
log.debug('listening for incoming packets from socket')
this.stream.on('message', messageProcess.bind(this))
this.stream.on('message', messageHandler.bind(this))
this.setKeepAlive(this.keepAlive,3000) // keep connection alive unless disabled
this.on('pushed', pushHandler )
this.on('error', errorHandler)
@ -262,30 +310,3 @@ class SocketConsumer extends Socket {
} // end class
export default SocketConsumer
// _removeListeners(events) {
// if (!events) this.removeAllListeners()
// else {
// if (typeof events === 'string') this.removeAllListeners(events)
// else events.map(event => this.removeAllListeners(event))
// }
// }
// Helper Functions
// wait until a passed ready function returns true
// function isReady(ready, wait = 100, timeout = 2000) {
// let time = 0
// return new Promise((resolve, reject) => {
// (function waitReady() {
// if (time > timeout)
// return reject(
// `timeout waiting for socket ready handshake - ${timeout}ms`
// )
// if (ready()) return resolve('ready')
// log.debug({function:'isReady', line:261, msg:`waiting ${wait}ms for handshake`})
// time += wait
// setTimeout(waitReady, wait)
// })()
// })
// }

View File

@ -57,15 +57,19 @@ export default function socketClass(Server) {
if (path.dirname(opts.path) === '.') // relative path sent
opts.path = path.join(DEFAULT_PIPE_DIR, opts.path)
}
this.allowAnonymous = process.env.UCI_ANON || opts.allowAnonymous || false
this.tokens = opts.tokens || []
this.keepAlive = 'keepAlive' in opts ? opts.keepAlive : true
this.pingInterval = opts.pingInterval === false ? opts.pingInterval : (opts.pingInterval * 1000 || 5000)
this.clientTracking = opts.clientTracking || true
// this.clientTracking = opts.clientTracking || true
this.clients = [] // track consumers (i.e. clients)
this.nextClientID = 0 // incrementer for simple client ID
this.nextClientID = 0 // incrementer for default initial client ID
this.opts = opts // for use to recover from selected errors
//self bindings
this._listen = this._listen.bind(this)
this.create = this.create.bind(this)
this.authenticateClient = this.authenticateClient.bind(this)
this._authenticate = this._authenticate.bind(this)
this.close = promisify(this.close).bind(this)
log = logger({
file: 'src/socket.js',
@ -119,11 +123,7 @@ export default function socketClass(Server) {
let [err, res] = await btc(this._listen)(this.opts)
if (err) reject(err)
if (this.pingInterval) {
this._ping = setInterval( async () =>{
if (this.clients.length > 0) this.push({pingInterval:this.pingInterval},'ping')
},this.pingInterval)
}
this.enablePing()
resolve(res)
}) // end creeate promise
} // end create
@ -138,6 +138,18 @@ export default function socketClass(Server) {
this._packetProcess = func
}
enablePing () {
if (this.pingInterval > 499) {
this._ping = setInterval( async () =>{
if (this.clients.length > 0) this.push({pingInterval:this.pingInterval},'ping')
},this.pingInterval)
}
}
disablePing() {
clearInterval(this._ping)
}
/**
* push - pushes a supplied UCI object packet to all connected clients
*
@ -147,18 +159,12 @@ export default function socketClass(Server) {
*/
async push(packet={},id) {
packet._header = {id: id || 'pushed'}
if (this.clients.length >0) {
if (this.clients.length > 0) {
log.debug({method:'push', line:142, id:packet._header.id, opts: this.opts, packet: packet, msg:'pushing a packet to all connected consumers'})
this.clients.forEach(async client => {
if (client.writable) {
let [err, ser] = await btc(client.stream.serialize)(packet)
if (err)
ser = await client.stream.serialize({
error: 'was not able to serialze the res packet',
err: err,
_header: { id: packet._header.id }
})
await this._send.bind(client)(ser)
let [err] = await btc(this._send)(client,packet)
if (err) log.error({msg:err, error:err})
}
})
} else {
@ -166,68 +172,113 @@ export default function socketClass(Server) {
}
}
removeClient (id) {
let index = this.clients.findIndex(client => {return client.id === id })
let client = this.clients[index]
client.removeAllListeners()
client.stream.removeAllListeners()
this.clients.splice(index,1)
log.warn({msg:'client removed from tracking',id:id, curClientCount:this.clients.length})
}
async authenticateClient(client) {
// let server = this
return new Promise(async function(resolve, reject) {
// when consumer gets the handshake they must follow with authentication
client.stream.on('message', authenticate.bind(this,client))
let [err] = await btc(this._send)(client,{_handshake: true, id:client.id})
if (err) {
log.error({msg:'error in handshake send', error:err})
reject(err)
}
async function authenticate (client,packet) {
log.info({msg:`authentication packet from client ${client.id}`, packet:packet})
client.stream.removeAllListeners('message')
if (!packet._authenticate) reject('first client packet was not authentication')
else {
let [err, res] = await btc(this._authenticate)(packet)
client.authenticated = this.allowAnonymous ? 'anonymous' : (err || res)
client.name = packet.clientName
packet.authenticated = client.authenticated
await this._send(client,packet) // send either way
if (err && !this.allowAnonymous) reject(client.authenticated)
else resolve(client.authenticated)
}
}
}.bind(this))
}
// private methods
// default authenticator
async _authenticate (packet) {
if (this.tokens.indexOf(packet.token) === -1) return Promise.reject(false)
return true
}
async _listen(opts) {
return super.listen(opts, async (err, res) => {
if (err) return Promise.reject(err)
// this gets called for each client connection and is unique to each
this.on('connection', async socket => {
const send = this._send.bind(socket)
const stream = new JSONStream()
socket.stream = stream // need this to track clients
if (this.clientTracking) {
this.nextClientID +=1
socket.id = this.nextClientID
this.clients.push(socket)
}
// TODO add 'close' listener to socket to remove from this.clients
log.debug({method:'_listen', line:167, msg:'new consumer connecting'})
log.debug(await send(await stream.serialize({ _handshake: true })))
if (this.opts.conPacket) {
this.opts.conPacket._header = { id: 'pushed' }
log.debug({method:'_listen', line:171, conPacket: this.opts.conPacket, msg:'pushing a preset command to just connected consumer'})
send(await stream.serialize(this.opts.conPacket)) // send a packet command on to consumer on connection
}
socket.id = ++this.nextClientID // server assigned ID
socket.authenticated = false
this.clients.push(socket) // add client to list
const stream = new JSONStream()
socket.stream = stream
socket.setKeepAlive(this.keepAlive,3000)
// add error and close listeners on connection
// add listeners
const clientCloseHandler = (id) => {
log.warn({msg:'client connection closed during listen,',id:id})
this.removeClient(id)
}
socket.on('close', clientCloseHandler.bind(this,socket.id) )
socket.on('error', (err) => {
log.error({msg:'client connection error during listen',error:err})
// TODO do more handling than just logging
})
const clientCloseHandler = (id, msg) => {
console.log('client that closed', id, msg,
)
this.clients.splice(this.clients.findIndex(client => {return client.id === id }),1)
console.log('number of active clients',this.clients.length)
log.warn({msg:'client connection closed during listen',id:this.id, error:msg})
}
console.log('binding on this client', socket.id)
socket.on('close', clientCloseHandler.bind(this,socket.id) )
socket.on('data', stream.onData) // send data to
stream.on('error', (err) => {
log.error({msg:'client-socket stream error during listen',error:err})
// TODO do more handling than just logging
})
socket.on('data', stream.onData)
// TODO need to start error listener for stream so errors can be processed
let [err] = await btc(this.authenticateClient)(socket)
if (!this.allowAnonymous) {
if (err) {
socket.end()// abort new connection socket, cleanup, remove listeners
this.removeClient(socket.id)
return
}
}
// all's set main message processor
stream.on('message', messageProcess.bind(this, socket))
if (this.opts.conPacket) {
this.opts.conPacket._header = { id: 'pushed' }
log.debug({method:'_listen', line:171, conPacket: this.opts.conPacket, msg:'pushing a preset command to just connected consumer'})
this._send(socket,this.opts.conPacket) // send a packet command on to consumer on connection
}
// that's it. Connection is active
async function messageProcess(client, packet) {
log.debug({method:'_listen', line:179, packet: packet, msg:'incoming packet on socket side'})
let res = {}
if (this.clientTracking && packet.clientID) {
client.ID = packet.clientID
res.cmd = 'ackID'
} else {
res = (await this._packetProcess(clone(packet))) || {}
if (Object.keys(res).length === 0)
res = {
error:
log.info({method:'_listen', line:179, packet: packet, client:client.name, msg:'incoming packet on socket side'})
let res = (await this._packetProcess(clone(packet))) || {}
if (Object.keys(res).length === 0)
res = {
error:
'socket packet command function likely did not return a promise',
packet: packet
}
}
packet: packet
}
if (packet) {
res._header = clone(packet._header, false) || {} //make sure return packet has header with id in case it was removed in processing
delete packet._header // remove before adding to response header as request
@ -236,44 +287,50 @@ export default function socketClass(Server) {
res._header.responder = { name: this.name, instanceID: this.id }
res._header.socket = this.address()
if (!res.cmd) res.cmd = 'reply' // by default return command is 'reply'
let [err, ser] = await btc(stream.serialize)(res)
if (err)
ser = await stream.serialize({
error: 'was not able to serialze the res packet',
err: err,
_header: { id: res._header.id }
})
await send(ser)
} // end process message
let [err] = await btc(this._send)(client,res)
if (err) log.error({msg:err, error:err})
} // end message process
}) // end connecttion handler
log.info({method:'_listen', line:255, opts: this.opt, msg:'socket created and listening'})
log.info({method:'_listen', line:255, opts: this.opt, msg:'socket server created and listening'})
return res
}) // end super listen callback
} // end listen
// call when socket server is going down
async _destroy() {
log.debug({method:'_destroy', line:217, msg:'closing down socket'})
log.fatal({method:'_destroy', line:217, msg:'closing down socket server'})
// this.push()
clearInterval(this._ping)
await this.close()
this.clients.forEach(client => {
client.removeAllListeners()
client.stream.removeAllListeners()
})
log.debug({method:'_destroy', line:219, msg:'all connections closed....exiting'})
process.exit()
}
// default packet process, just a simple echo
// default packet process, just a simple echo, override with registerPacketProcessor
async _packetProcess(packet) {
return new Promise(resolve => {
resolve(packet)
})
}
// consumer send, must have a consumer socket bound to use
async _send(packet) {
// timeout already set if sockect can't be drained in 10 secs
return new Promise(resolve => {
async _send(client, packet) {
log.debug({msg:`sending to client:${client.id}`, packet:packet})
return new Promise(async (resolve, reject) => {
let [err,ser] = await btc(client.stream.serialize)(packet)
if (err) reject('unable to serialze the packet')
const cb = () => resolve('packet written to socket stream')
if (!this.write(packet)) {
this.once('drain', cb)
if (!client.write(ser)) {
client.once('drain', cb)
} else {
process.nextTick(cb)
}