socket example socket server with select (snippet)

Python socket example 'socket server with select'

Modules used in program:

import socket, select

python socket server with select

Python socket example: socket server with select

#!/usr/bin/python
# Socket server in python using select function
# credits: http://www.binarytides.com/python-socket-server-code-example/

import socket, select

if __name__ == "__main__":

    CONNECTION_LIST = []    # list of socket clients
    RECV_BUFFER = 4096 # Advisable to keep it as an exponent of 2
    PORT = 5000

    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    # this has no effect, why ?
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_socket.bind(("0.0.0.0", PORT))
    server_socket.listen(10)

    # Add server socket to the list of readable connections
    CONNECTION_LIST.append(server_socket)

    print("Chat server started on port " + str(PORT))

    while 1:
        # Get the list sockets which are ready to be read through select
        read_sockets,write_sockets,error_sockets = select.select(CONNECTION_LIST,[],[])

        for sock in read_sockets:

            #New connection
            if sock == server_socket:
                # Handle the case in which there is a new connection recieved through server_socket
                sockfd, addr = server_socket.accept()
                CONNECTION_LIST.append(sockfd)
                print("Client (%s, %s) connected" % addr)

            #Some incoming message from a client
            else:
                # Data recieved from client, process it
                try:
                    #In Windows, sometimes when a TCP program closes abruptly,
                    # a "Connection reset by peer" exception will be thrown
                    data = sock.recv(RECV_BUFFER)
                    # echo back the client message
                    if data:
                        sock.send('OK ... ' + data)

                # client disconnected, so remove from socket list
                except:
                    broadcast_data(sock, "Client (%s, %s) is offline" % addr)
                    print("Client (%s, %s) is offline" % addr)
                    sock.close()
                    CONNECTION_LIST.remove(sock)
                    continue

    server_socket.close()

Python links

Learn Python: https://pythonbasics.org/
Python Tutorial: https://pythonprogramminglanguage.com