python tcp server sending data to multiple clients

Question

i am having trouble trying to send data to all clients connected on my python tcp chat server. i know how to get the message/data to send right back to the person who sent it but it just won't send back if i have multiple clients. this is my server so far:

host = '127.0.0.1'
port = 4446
backlog = 5
size = 1024

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind( (host, port) )
s.listen(backlog)
clients = [s]

while 1:
  inputReady, outputReady, exceptReady = select.select(clients, [], [])
  for x in inputReady: 

    if x == s: 
        csock, addr = s.accept() 
        clients.append(csock) 

    else:  
        data = x.recv(size) 
        if data: 
            for i in clients: #problem i believe is in here but i
                i.send(data)  #dont know how to fix it
        else: 
            x.close() 
            clients.remove(x) 
s.close()

i am using node.js for the client side and its very simple so far and i dont think its the problem:

var net = require('net');
var readline = require('readline');

var host = process.argv[2];
var port = process.argv[3];
var username = process.argv[4];
var client = new net.Socket();

client.connect(port, host, function(){
    var type = "connect";
    var sender = username;
    var msg = "has connected";
    var s = type + ':' + sender + ':' + msg;
    var length = s.length;
    client.write(length + " " + s);
});

client.on('data', function(data){
    console.log(data.toString('UTF-8'));
});

There's a bug in your sending code that you didn't notice. You forgot to check the return value of send. Read the documentation for that method to learn why this is necessary. You're also using blocking sockets which means your server can only process data as fast as the slowest client can process it. You may want to take a look at twistedmatrix.com for an easier approach to network programming in Python (it's like Node.js for Python!) — Jean-Paul Calderone
– Jean-Paul Calderone, Commented Feb 11, 2014 at 13:17

epx · Accepted Answer · 2014-02-11 01:51:09Z

2

The problem is that you are sending on all sockets, including the server socket (s). Ignoring other potential problems, you can do a quick fix by doing this:

       for i in clients:
          if i is not s:
            i.send(data)

answered Feb 11, 2014 at 1:51

epx

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