I have two backends. Backend A and Backend B.
Backend B sends and receives info using a socket server running at port 4243.
Then, with Backend A, I need to catch that info and save it. But I have to also have a socket server on Backend A running at port 4243.
The problem is that, when I run Backend A after running Backend B I receive the error "EADDRINUSE", because I'm using the same host:port on both apps.
If, for Backend A I use Python, the problem dissapear because I have a configuration for sockets that's called SO_REUSEADDR.
Here we have some examples:
https://www.programcreek.com/python/example/410/socket.SO_REUSEADDR
https://subscription.packtpub.com/book/networking-and-servers/9781849513463/1/ch01lvl1sec18/reusing-socket-addresses
But, I want to use JavaScript for coding my Backend A, so I was using the net package for coding the sockets, and I can't get it to work, because of the "EADDRINUSE" error.
The NodeJS documentation says that "All sockets in Node set SO_REUSEADDR already", but it doesn't seem to work for me...
This is my code so far:
// Step 0: Create the netServer and the netClient
console.log(`[DEBUG] Server will listen to: ${HOST}:${PORT}`);
console.log(`[DEBUG] Server will register with: ${AGENT_ID}`);
const netServer = net.createServer((c) => {
console.log('[netServer] Client connected');
c.on('message', (msg) => {
console.log('[netServer] Received `message`, MSG:', msg.toString());
});
c.on('*', (event, msg) => {
console.log('[netServer] Received `*`, EVENT:', event);
console.log('[netServer] Received `*`, MSG:', msg);
});
}).listen({
host: HOST, // 'localhost',
port: PORT, // 4243,
family: 4, // ipv4, same as socket.AF_INET for python
});
// Code copied from nodejs documentation page (doesn't make any difference)
netServer.on('error', function (e) {
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
netServer.close();
netServer.listen(PORT, HOST);
}, 1000);
}
});
const netClient = net.createConnection(PORT, HOST, () => {
console.log('[netClient] Connected');
});
// Step 1: Register to instance B of DTN with agent ID 'bundlesink'
netClient.write(serializeMessage({
messageType: AAPMessageTypes.REGISTER,
eid: AGENT_ID,
}));
With this code, I get the following output in the terminal:
But, with the Python code, the socket connects successfully:
I don't know what to do :(
I hope I get some help here.
Edit 1
By the way, the lsof command, throws me this output for the JavaScript backend:
And this other output for the Python backend:
Edit 2
It really seems to be a problem with JavaScript. I also found this snippet:
var net = require('net');
function startServer(port, host, callback) {
var server = net.createServer();
server.listen(port, host, function() {
callback(undefined, server);
});
server.on('error', function(error) {
console.error('Ah damn!', error);
callback(error);
});
}
startServer(4000, '0.0.0.0', function(error, wildcardServer) {
if (error) return;
startServer(4000, '127.0.0.1', function(error, localhostServer) {
if (error) return;
console.log('Started both servers!');
});
});
From this post:
https://medium.com/#eplawless/node-js-is-a-liar-sometimes-8a28196d56b6
As the author says:
Well, that prints “Started both servers!” which is exactly what we don’t want.
But for me, instead of printing that, I get an error:
Ah damn! Error: listen EADDRINUSE: address already in use 127.0.0.1:4000
at Server.setupListenHandle [as _listen2] (node:net:1319:16)
at listenInCluster (node:net:1367:12)
at doListen (node:net:1505:7)
at processTicksAndRejections (node:internal/process/task_queues:84:21) {
code: 'EADDRINUSE',
errno: -98,
syscall: 'listen',
address: '127.0.0.1',
port: 4000
}
I really cannot make it to run and print "Started both servers!".
Because that's what I want my code to do.
Edit 3
This is the Python server socket: https://gitlab.com/d3tn/ud3tn/-/blob/master/tools/aap/aap_receive.py
This is the important part:
addr = (args.tcp[0], int(args.tcp[1])) # args.tcp[0] = "localhost", args.tcp[1] = "4243"
with AAPTCPClient(address=addr) as aap_client:
aap_client.register(args.agentid) # args.agentid = "bundlesink"
run_aap_recv(aap_client, args.count, args.verify_pl)
It creates an AAPTCPClient, and the only thing that AAPTCPClient does, is the following:
def __init__(self, socket, address):
self.socket = socket
self.address = address
self.node_eid = None
self.agent_id = None
def register(self, agent_id=None):
"""Attempt to register the specified agent identifier.
Args:
agent_id: The agent identifier to be registered. If None,
uuid.uuid4() is called to generate one.
"""
self.agent_id = agent_id or str(uuid.uuid4())
logger.info(f"Sending REGISTER message for '{agent_id}'...")
msg_ack = self.send(
AAPMessage(AAPMessageType.REGISTER, self.agent_id)
)
assert msg_ack.msg_type == AAPMessageType.ACK
logger.info("ACK message received!")
def send(self, aap_msg):
"""Serialize and send the provided `AAPMessage` to the AAP endpoint.
Args:
aap_msg: The `AAPMessage` to be sent.
"""
self.socket.send(aap_msg.serialize())
return self.receive()
def receive(self):
"""Receive and return the next `AAPMessage`."""
buf = bytearray()
msg = None
while msg is None:
data = self.socket.recv(1)
if not data:
logger.info("Disconnected")
return None
buf += data
try:
msg = AAPMessage.parse(buf)
except InsufficientAAPDataError:
continue
return msg
I don't see any bind, and I don't understand why the python code can call "socket.recv", but in my JavaScript code I can't do "netServer.listen". I think it should be the same.
There are things to clarify.
1.) The client uses the bind syscall where the kernel selects the source port automatically.
It does so by checking sys local_portrange sysctl settings.
1.) If you want to bind the client to a static source port, be sure to select a TCP port outside the local_portrange range !
2.) You cannot subscribe to event "*", instead you've to subscribe to the event "data" to receive messages.
For best practice you should also subscribe to the "error" event in case of errors !
These links will get you started right away:
How do SO_REUSEADDR and SO_REUSEPORT differ?
https://idea.popcount.org/2014-04-03-bind-before-connect/
So, for all beginners, who want to dig deeper into networking using node.js…
A working server example:
// Step 0: Create the netServer and the netClient
//
var HOST = 'localhost';
var PORT = 4243;
var AGENT_ID = 'SO_REUSEADDR DEMO';
var net = require('net');
console.log(`[DEBUG] Server will listen to: ${HOST}:${PORT}`);
console.log(`[DEBUG] Server will register with: ${AGENT_ID}`);
const netServer = net.createServer((c) => {
console.log('[netServer] Client connected');
c.on('data', (msg) => {
console.log('[netServer] Received `message`, MSG:', msg.toString());
});
c.on('end', () => {
console.log('client disconnected');
});
c.on('error', function (e) {
console.log('Error: ' + e.code);
});
c.write('hello\r\n');
c.pipe(c);
}).listen({
host: HOST,
port: PORT,
family: 4, // ipv4, same as socket.AF_INET for python
});
// Code copied from nodejs documentation page (doesn't make any difference)
netServer.on('error', function (e) {
console.log('Error: ' + e.code);
if (e.code == 'EADDRINUSE') {
console.log('Address in use, retrying...');
setTimeout(function () {
netServer.close();
netServer.listen(HOST, PORT);
}, 1000);
}
if ( e.code = 'ECONNRESET' ){
console.log('Connection reset by peer...');
setTimeout(function () {
netServer.close();
netServer.listen(HOST, PORT);
}, 1000);
}
});
The Client:
/* Or use this example tcp client written in node.js. (Originated with
example code from
http://www.hacksparrow.com/tcp-socket-programming-in-node-js.html.) */
var net = require('net');
var HOST = 'localhost';
var PORT = 4243;
var client = new net.Socket();
client.setTimeout(3000);
client.connect(PORT, HOST, function() {
console.log("Connected to " + client.address().address + " Source Port: " + client.address().port + " Family: " + client.address().family);
client.write('Hello, server! Love, Client.');
});
client.on('data', function(data) {
console.log('Received: ' + data);
client.end();
});
client.on('error', function(e) {
console.log('Error: ' + e.code);
});
client.on('timeout', () => {
console.log('socket timeout');
client.end();
});
client.on('close', function() {
console.log('Connection closed');
});
Best Hannes
Steffen Ullrich was completely right.
In my JavaScript code, I was trying to create a server to listen to the port 4243.
But you don't need to have a server in order to listen to some port, you can listen with a client too! (At least that's what I understood)
You can create a client connection as following:
const netClient = net.createConnection(PORT, HOST, () => {
console.log('[netClient] Connected');
});
netClient.on('data', (data) => {
console.log('[netClient] Received data:', data.toString('utf8'));
});
And with "client.on", then you can receive messages as well, as if it were a server.
I hope this is useful to someone else.
I have socket.io set up and working and now I need to send updates to the users via the same sockets, the updates I get from a different server (the other server makes a GET http request to my nodejs server and I need to take the data from that http request and emit it to a certain user via sockets)
Here's my code, emitting sockets from inside the socket process works fine but from inside the API call doen't work.
var express = require("express");
var app = express();
var http = require("http").createServer(app);
var io = require("socket.io")(http);
app.set('socketIo', io);
io.on("connection", (socket) => {
console.log("User connected: ", socket.id);
io.to(socket.id).emit("new_message", {id: "999", msg: "You are connected, your Id is " + socket.id});
})
app.get("/send/:id/:message", (request, result) => {
const ioEmitter = request.app.get("socketIo");
ioEmitter.to(request.params.id).emit({ id: "999", msg: request.params.message });
result.send("Sending message to socket Id: " + request.params.id)
console.log("Sending message to socket Id: " + request.params.id);
})
const port = 3001;
http.listen(port, () => {
console.log("Listening to port " + port);
});
I am trying to deploy my node.js application to digital ocean. Locally my app works fine when I do:
node server.js
I cloned my repository from gitlab with ssh access and tried doing the same thing, but all the page does is being stuck on the loading stage and eventually it says that my ip address took too long to respond.
ERR_CONNECTION_TIMED_OUT
Eventually I am planning on using something to make it run permanently but I will post a separate post for that.
I normally user my ip address:port number to try view my application.
this is my server.js file:
const express = require('express') ,app = express(), path = require('path'),
socket = require('socket.io'), emailModule = require('./email.js'),
formValidationModule = require('./formValidation.js'), vimeoModule = require('./vimeo.js'),
port = process.env.PORT || 3000;
let
server = app.listen(port,function(){
console.log('listening to requests...');
}),
io = socket(server);
app.get('/', function(req, res) {
res.sendFile(path.join(__dirname + '/index.html'));
});
io.on('connection', (socket)=>{
console.log('made a connection!');
socket.on('getShortFilmsInfo', ()=>{
vimeoModule.videos.short_films.forEach((y)=>{
vimeoModule.getVideoThumbnail(y).then((data)=>{
socket.emit('shortFilmsInfo', data);
});
})
});
socket.on('getCommercials',()=>{
vimeoModule.videos.commercials.forEach((x)=>{
vimeoModule.getVideoThumbnail(x).then((data)=>{
socket.emit('commercialInfo', data);
})
});
});
socket.on('email', (data)=>{
if(formValidationModule.checkEmptyContact(data.client, data.email, data.name,
data.title, data.message)){
socket.emit('invalidData');
}
else {
/**
* * Here you need to set your email options which includes the clients email, destination email,
* subject and the text (the email content).
*/
emailModule.setMailOptions(data.email,/*'Info#project-gorilla.co.uk'*/'salay777#hotmail.co.uk'
, data.client + ' ' + '(' +
data.name + ')' + ' ' + data.title, data.message).then((mailOpts)=>{
emailModule.send(mailOpts);
});
console.log('email has been sent!');
}
});
});
Port on which you are running node application in digital ocean is blocked from outside access. Configure digital ocean to route any request on port 80 or 443 ( default port for http and https ) to your internal nodejs application.
With the out of date docs on sails' sockets implementation i'm struggling to get the basic 'connect' message. Here's my node.js server side code:
sails.sockets.on('connection', function(socket){
sails.log.info('socket connected');
//create room and broadcast a welcome message
socket.emit('user joined', {'message': 'Welcome to ' + roomName});
socket.join(roomName);
socket.broadcast.to(roomName).emit('user joined', {'message': 'Welcome to ' + roomName});
});
and my client side:
var sock = io.connect('http://localhost:8888');
sock.on('connection', function(socket){
console.log('conected to server');
});
sock.on('user joined', function (json) {
console.log('socket: ' + json);
});
I do get the OK message from sails itself on start up but can't seem to get a connection of my own:
sails.io.js:200 `io.socket` connected successfully.
(for help, see: http://sailsjs.org/#!documentation/reference/BrowserSDK/BrowserSDK.html)
I tried using socket.io v1 and got the same weird situation. any ideas? thanks!
On server config/sockets.js
module.exports.sockets = {
onConnect: function(session, socket) {
sails.log.verbose('>>> socket user connected');
sails.sockets.blast('eventName', dataToBlast);
},
};
Documentation http://sailsjs.org/#/documentation/anatomy/myApp/config/sockets.js.html
On client
io.socket.on('eventName', function(dataToBlast) {
// process dataToBlast
});
Documentation http://sailsjs.org/#/documentation/reference/websockets/sails.io.js/io.socket.on.html
Be aware that socket needs to be subscribed to eventName. To subscribe you need to make controller SubscribeController.js and make request to it's action via socket.
var SubscribeController = {
sub: function(req, res) {
ModelName.subscribe(
req.socket,
[] /*records to subscribe to or empty array to subscribe to all */,
['eventName'] /* array of strings eventNames */
);
},
};
For debugging client you can connect to firehose which will give your client all messages from sails server
io.socket.get('/firehose');
io.socket.on('firehose', function newMessageFromSails(message) {
typeof console !== 'undefined' &&
console.log('New message published from Sails ::\n', message);
});
My nodejs server is unable to detect when a new browser connects ('connection' event) and I dont know why. I narrowed down a problem working on it for a few days and suspect that is has to due with the addition of the pubnub socket connection implemented on the browser.
The following is my server.js
var http = require('http')
, connect = require('connect')
, io = require('socket.io')
, fs = require('fs')
, uuid = require('node-uuid')
, _ = require('lodash');
// pubnub!!! (how to initialize it for use on server)
var pubnub = require('pubnub').init({
channel: "my_channel",
publish_key: "pub-key",
subscribe_key: "sub-c-key",
uuid: "Server",
origin : 'pubsub.pubnub.com'
});
pubnub.subscribe({
channel: 'my_channel',
callback: function(message) {
console.log("Message received: ", message);
},
message: 'Server ready',
presence: function(data) {
console.log("Presense: ", data);
},
connect: publish
});
// various socket.on() events omitted
var app = connect().use(connect.static(__dirname)).use(connect.directory(__dirname));
var server = http.createServer(app);
server.listen(8888);
io = io.listen(server);
io.sockets.on('connection', handleNewPeer);
Upon arriving on the html page, the doConnect(isBroadcaster) function is ran from script tag
The doConnect function (In peer.js):
var doConnect = function(isBroadcaster) {
console.log("doConnect");
// broadcaster or normal peer
var user;
if (isBroadcaster)
user = "Broadcaster";
else
user = "Viewer";
(function() {
var pubnub_setup = {
channel: "my_channel",
publish_key: "pub-c-key",
subscribe_key: "sub-c-key",
user: user
};
// Note removed the var
socket = io.connect( 'http://pubsub.pubnub.com', pubnub_setup);
// various socket.on() omitted
})();
Here is what how it was before with just socketIO & it was working:
var doConnect = function(isBroadcaster) {
socket = io.connect();
// various socket.on() omitted
}
My p2p video website is implemented with WebRTC running on a Nodejs + SocketIO server.
I have been trying to incorporate pubnub into it & thought it would be easy since pubnub supports SocketIO (or at least client side?). Really did not think it would be this difficult to set up server side.
Any input at all on this? I think it's something simple that I just cannot put my finger on
Socket.IO on the Server using Node.JS
Socket.IO with PubNub does not provide a Node.JS Socket.IO backend option. However you can use the PubNub SDK directly for on-connect events.
NPM Package
npm install pubnub
After you install the PubNub NPM you can use the node.js server backend:
Node.js Backend Code
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// PubNub!!! (how to initialize it for use on server)
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
var pubnub = require('pubnub').init({
publish_key : "pub-key",
subscribe_key : "sub-c-key",
uuid : "Server-ID"
});
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// On user Connect
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
function on_user_connect(data) {
console.log( "User Connected: ", data.uuid );
}
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// On user Leave
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
function on_user_leave(data) {
console.log( "User Left: ", data.uuid );
}
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
// Open Socket Connection for User Join Events
// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
pubnub.subscribe({
channel : 'my_channel',
connect : connected
message : function(message) {
console.log("Message received: ", message);
},
presence : function(data) {
if (data.action == "leave") on_user_leave(data);
if (data.action == "timeout") on_user_leave(data);
if (data.action == "join") on_user_connect(data);
}
});
function connected() {
console.log('connected!');
}
What version of socket.io are you using?
This might not fix it. I am using version 1.+ Have you tried:
io.on('connection', function(socket){
console.log('user connected');
});