chat_server.py

#!/usr/bin/env python
#
# usage - in one window type
# chat_server.py --name=server --port=8080 or whatever
# in another window
# chat_server.py --name-client1 --port=8080 or whatever your server was
# thanks to faruq

import select
import socket
import sys
import signal
import cPickle
import struct
import argparse

SERVER_HOST = 'localhost'
CHAT_SERVER_NAME = 'server'

def send(channel, *args):
    buffer = cPickle.dumps(args)
    value = socket.htonl(len(buffer))
    size = struct.pack("L", value)
    channel.send(size)
    channel.send(buffer)

def receive(channel):
    size = struct.calcsize("L")
    size = channel.recv(size)
    try:
        size = socket.ntohl(struct.unpack("L", size) [0])
    except struct.error, e:
        return ''
    buf = ""
    while len(buf) < size:
        buf = channel.recv(size -len(buf))
        return cPickle.loads(buf)[0]


class ChatServer(object):
    """ An example chat server using select"""
    def __init__(self, port, backlog=5):
        self.clients = 0
        self.clientmap = {}
        self.outputs = []  # list output sockets
        self.server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        # Enable reusing socket address
        self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.server.listen(backlog)
        # Catch keyboard interrupts
        signal.signal(signal.SIGINT, self.sighandler)

    def sighandler(self, signum, frame):
        """ Clean up clients outputs"""
        # Close the server
        print 'Shutting down server...'
        # Close existing client sockets
        for output in self.outputs:
            output.close()
        self.server.close()

    def get_client_name(self, client):
        """ Return the name of the client"""
        info = self.clientmap[client]
        host, name = info[0][0], info[1]
        return '@'.join((name, host))

    def run(self):
        inputs = [self.server, sys.stdin]
        self.outputs = []
        running = True
        while running:
            try:
                readable, writeable, exceptional = \
                select.select(inputs, self.outputs, [])
            except select.error, e:
                    break
            for sock in readable:
                if sock == self.server:
                    # handle the server socket
                    client, address = self.server.accept()
                    print "Chat server: got connection %d from %s" %\
                    (client.fileno(), address)
                    # Read the login name
                    cname = receive(client).split('NAME: ')[1]
                    # Compute the clients name and send back
                    self.clients += 1
                    send(client, 'CLIENT: ' + str(address[0]))
                    inputs.append(client)
                    self.clientmap[client] = (address, cname)
                    # Send joining information to other clients
                    msg = "\n(Connected: New client (%d) from %s)" %\
                    (self.clients, self.get_client_name(client))
                    for output in self.outputs:
                        send(output, msg)
                    self.outputs.append(client)
                elif sock == sys.stdin:
                    # handle standard input
                    junk = sys.stdin.readline()
                    running = False
                else:
                    # Handle all other sockets
                    try:
                        data = receive(sock)
                        if data:
                            # Send as new client's message...
                            msg = '\n#[' + self.get_client_name(sock)\
                            + ']>>' + data
                            # Send data to all except ourself
                            for output in self.outputs:
                                if output != sock:
                                    send(output, msg)

                            else:
                                print "Chat server: %d hung up" % \
                                sock.fileno()
                                self.clients -= 1
                                sock.close()
                                inputs.remove(sock)
                                self.outputs.remove(sock)
                                # Sending client leaving info to others
                                msg = "\n(Now hung up: Client from %s)" %\
                                self.get_client_name(sock)
                                for output in self.outputs:
                                    send(output, msg)
                    except socket.error, e:
                        # Remove
                        inputs.remove(sock)
                        self.outputs.remove(sock)
            self.server.close()


class ChatClient(object):
    """ A command line chat client using select """

    def __init__(self, name, port, host=SERVER_HOST):
        self.name = name
        self.connected = False
        self.host = host
        self.port = port
        # Initial prompt
        self.prompt='[' + '@'.join((name, socket.gethostname().split('.') [0])) + ']> '
        # Connect to server at port
        try:
            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            self.sock.connect((host, self.port))
            print "Now connected to chat server@ port %d" % self.port
            self.connected = True
            # Send my name ...
            send(self.sock, 'NAME: ' + self.name)
            data = receive(self.sock)
            # Contains client address, set it
            addr = data.split('CLIENT: ') [1]
            self.prompt = '[' + '@'.join((self.name, addr)) + ']> '
        except socket.error, e:
            print "Failed to connect to chat server @ port %d" % self.port
            sys.exit(1)

    def run(self):
        """ Chat client main loop """
        while self.connected:
            try:
                sys.stdout.write(self.prompt)
                sys.stdout.flush()
                # Wait for input from stdin and socket
                readable, writeable, exceptional = select.select([0, self.sock], [], [])
                for sock in readable:
                    if sock == 0:
                        data = sys.stdin.readline().strip()
                        if data: send(self.sock, data)
                    elif sock == self.sock:
                        data = receive(self.sock)
                        if not data:
                            print 'Client shutting down.'
                            self.connected = False
                            break
                        else:
                            sys.stdout.write(data + '\n')
                            sys.stdout.flush()

            except KeyboardInterrupt:
                print " Client interrupted. """
                self.sock.close()
                break

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Socket Server with Select')
    parser.add_argument('--name', action="store", dest="name", required=True)
    parser.add_argument('--port', action="store", dest="port", type=int, required=True)
    given_args = parser.parse_args()
    port = given_args.port
    name = given_args.name
    if name == CHAT_SERVER_NAME:
        server = ChatServer(port)
        server.run()
    else:
        client = ChatClient(name=name, port=port)
        client.run()
""" so when i run this program on desktop computer i get the error
that it Failed to connect on port xxxxx as was coded into the chat
client part of the program, this might be due to the locked-down nature
of that computer. I will rerun this on my dev laptop latter, but i think
its working finally  """