node.js uncompleted chat socket test

client.js

var net = require('net');

var client = net.connect(5891, function() {
	console.log('Connected to server');
});

client.on('data', function(data) {
	var command = JSON.parse(new Buffer(data).toString());

	switch(command.name) {
		case 'SHOW OPTIONS':
			console.log('Please select options:');
			console.log('1. Say');
			console.log('2. List messages');
			console.log('3. List users');
			console.log('4. Logout');

			ask("Your options: ", /[1-4]/, function(options) {
				client.write('OPTIONS ' + options);
			});
			break;

		case 'LIST USERS':
			var user_list = command.value;

			for(var i in user_list) {
				console.log('- %s', user_list[i].ip);
			}
			break;

		case 'LOGOUT':
			console.log('Bye!');
			process.exit(1);
			break;
	}
});

function ask(question, format, callback) {
	var stdin = process.stdin, stdout = process.stdout;

	stdin.resume();
	stdout.write(question);

	stdin.once('data', function(data) {
		data = data.toString().trim();

		if (format.test(data)) {
			callback(data);
		} else {
			stdout.write("It should match: "+ format +"\n");
			ask(question, format, callback);
		}
	});
}

server.js

var net = require('net');
var users = [];

var server = net.createServer({ allowHalfOpen: true }, function(socket) {
	socket.setEncoding("utf8");

	socket.on('connect', function() {
		console.log('[Connected] ' + socket.remoteAddress);

		socket.write(command('SHOW OPTIONS'), function() {
			users[socket] = socket.remoteAddress;
		});
	});

	socket.on('data', function(data) {
		var data_parts = data.split(' ');
		var command = data_parts[0];
		var value = data_parts[1];

		switch(command) {
			case 'OPTIONS':
				if (value < 1 && value > 4) {
					socket.write(command('SHOW OPTIONS'));
				}else{
					runOptions(socket, value);
				}
				break;
		}
	});

	socket.on('end', function() {
		users[socket] = null;

		console.log('[Disconnect] ' + socket.remoteAddress);
	});
}).listen(5891, function() {
	console.log('Server started at ' + server.address().address + ':' + server.address().port);
});

function command(name, value) {
	return JSON.stringify({
		name: name,
		value: value
	});
}

function runOptions(socket, options) {
	if (options == 3) {
		var user_list = [];
		for(var i in users) {
			user_list.push({
				ip: users[i],
				owner: i == socket
			});
		}
		console.log(user_list);
		socket.write(command('LIST USERS', user_list), function() {
			socket.write(command('SHOW OPTIONS'));
		});
	}else if (options == 4) {
		socket.write(command('LOGOUT'));
	}
}