Python Socket Multiple Clients

Question

So I am working on an iPhone app that requires a socket to handle multiple clients for online gaming. I have tried Twisted, and with much effort, I have failed to get a bunc

Answer 1

This program will open 26 sockets where you would be able to connect a lot of TCP clients to it.

#!usr/bin/python
from thread import *
import socket
import sys

def clientthread(conn):
    buffer=""
    while True:
        data = conn.recv(8192)
        buffer+=data
        print buffer
    #conn.sendall(reply)
    conn.close()

def main():
    try:
        host = '192.168.1.3'
        port = 6666
        tot_socket = 26
        list_sock = []
        for i in range(tot_socket):
            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
            s.bind((host, port+i))
            s.listen(10)
            list_sock.append(s)
            print "[*] Server listening on %s %d" %(host, (port+i))

        while 1:
            for j in range(len(list_sock)):
                conn, addr = list_sock[j].accept()
                print '[*] Connected with ' + addr[0] + ':' + str(addr[1])
                start_new_thread(clientthread ,(conn,))
        s.close()

    except KeyboardInterrupt as msg:
        sys.exit(0)


if __name__ == "__main__":
    main()

Answer 2

#!/usr/bin/python
import sys
import os
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)         
port = 50000

try:
    s.bind((socket.gethostname() , port))
except socket.error as msg:
    print(str(msg))
s.listen(10)
conn, addr = s.accept()  
print 'Got connection from'+addr[0]+':'+str(addr[1]))
while 1:
        msg = s.recv(1024)
        print +addr[0]+, ' >> ', msg
        msg = raw_input('SERVER >>'),host
        s.send(msg)
s.close()

Answer 3

accept can continuously provide new client connections. However, note that it, and other socket calls are usually blocking. Therefore you have a few options at this point:

• Open new threads to handle clients, while the main thread goes back to accepting new clients
• As above but with processes, instead of threads
• Use asynchronous socket frameworks like Twisted, or a plethora of others

Answer 4

Based on your question:

My question is, using the code below, how would you be able to have multiple clients connected? I've tried lists, but I just can't figure out the format for that. How can this be accomplished where multiple clients are connected at once and I am able to send a message to a specific client?

Using the code you gave, you can do this:

#!/usr/bin/python           # This is server.py file                                                                                                                                                                           

import socket               # Import socket module
import thread

def on_new_client(clientsocket,addr):
    while True:
        msg = clientsocket.recv(1024)
        #do some checks and if msg == someWeirdSignal: break:
        print addr, ' >> ', msg
        msg = raw_input('SERVER >> ')
        #Maybe some code to compute the last digit of PI, play game or anything else can go here and when you are done.
        clientsocket.send(msg)
    clientsocket.close()

s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 50000                # Reserve a port for your service.

print 'Server started!'
print 'Waiting for clients...'

s.bind((host, port))        # Bind to the port
s.listen(5)                 # Now wait for client connection.

print 'Got connection from', addr
while True:
   c, addr = s.accept()     # Establish connection with client.
   thread.start_new_thread(on_new_client,(c,addr))
   #Note it's (addr,) not (addr) because second parameter is a tuple
   #Edit: (c,addr)
   #that's how you pass arguments to functions when creating new threads using thread module.
s.close()

As Eli Bendersky mentioned, you can use processes instead of threads, you can also check python threading module or other async sockets framework. Note: checks are left for you to implement how you want and this is just a basic framework.

Answer 5

Here is the example from the SocketServer documentation which would make an excellent starting point

import SocketServer

class MyTCPHandler(SocketServer.BaseRequestHandler):
    """
    The RequestHandler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the
    client.
    """

    def handle(self):
        # self.request is the TCP socket connected to the client
        self.data = self.request.recv(1024).strip()
        print "{} wrote:".format(self.client_address[0])
        print self.data
        # just send back the same data, but upper-cased
        self.request.sendall(self.data.upper())

if __name__ == "__main__":
    HOST, PORT = "localhost", 9999

    # Create the server, binding to localhost on port 9999
    server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)

    # Activate the server; this will keep running until you
    # interrupt the program with Ctrl-C
    server.serve_forever()

Try it from a terminal like this

$ telnet localhost 9999
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Hello
HELLOConnection closed by foreign host.
$ telnet localhost 9999
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Sausage
SAUSAGEConnection closed by foreign host.

You'll probably need to use A Forking or Threading Mixin too