client undefined

app.js

var mosca = require('mosca');
var mqtt = require('mqtt');
var client = mqtt.createClient(1883, "localhost", {username: "user", password: "pass"});

var moscaSettings = {
    port: 1883,
}

var server = new mosca.Server(moscaSettings);
server.on('ready', setup);

server.on('clientConnected', function (client) {
    console.log(client);
});

server.on('published', function (packet, client) {
	console.log(client);
});

client.on('connect', function () {
    client.subscribe('stuff');
});

function setup() {
	server.authenticate = authenticate;
}

var authenticate = function (client, username, password, callback) {
	var connectiona = {test: "test"};
	client.connectiona = connectiona;
	client.user = username;
	authorized = true;
  callback(null, authorized);
}