socket-based simple python chat program

Question

I am writing a simple socket-based chat program that allows the server to send and receive message to the client. The client can send message to server but when I try sending a message from the server, it crashes saying that 'file' objects has attribute 'recv'.

Server.py

import socket
import os
import select
import sys

def prompt():
    sys.stdout.write('<You> ')
    sys.stdout.flush()

try:
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except:
    print 'Failed to create socket'
    sys.exit()

PORT = 9050
HOST = '127.0.0.1'
RECV_BUFFER = 4096

server_socket.bind((HOST, PORT))
server_socket.listen(10)

input = [server_socket, sys.stdin]

print 'Chat Program'
prompt()

while 1:

    inputready, outputready, exceptready = select.select(input,[],[])

    for sock in inputready:

        if sock == server_socket:
            client, address = server_socket.accept()
            input.append(client)
            #data = sock.recv(RECV_BUFFER)
            #if data:
                #sys.stdout.write(data)
        else:
            data = sock.recv(RECV_BUFFER)
            if data:
                sys.stdout.write(data)
            else:
                msg = sys.stdin.readline()
                server_socket.send('\r<Server>: ' + msg)
                prompt()



server_socket.close()

Client.py

import socket
import os
import select
import sys

def prompt():
   sys.stdout.write('<You> ')
   sys.stdout.flush()

HOST = '127.0.0.1'
PORT = 9050
try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
    print 'Failed to create socket'
    sys.exit()

s.connect((HOST, PORT))

print 'Connected to remote host. Start sending messages'
prompt()

while 1:

    socket_list = [sys.stdin, s]

    read_sockets, write_sockets, error_sockets = select.select(socket_list, [], [])

    for sock in read_sockets:
        if sock == s:
            data = sock.recv(4096)
            if not data:
                print '\nDisconnected from chat server'
                sys.exit()
            else:
                sys.stdout.write(data)
                prompt()
        else:
            msg = sys.stdin.readline()
            s.send('\r<Client>: ' + msg)
            prompt()

Answer 1

Well, in your server you are doing (abbreviated)

input = [server_socket, sys.stdin]
inputready, outputready, exceptready = select.select(input,[],[])
for sock in inputready:
    if sock == server_socket:
        ...
    else:
        data = sock.recv(RECV_BUFFER)

So when something comes in on sys.stdin, its not server_socket so it goes to the else and tries to recv, but its not a socket. stdin should be using read not recv. Structure like the one below makes the most sense to me.

if sock == server_socket:
    ...
elif sock == sys.stdin:
    data = sock.readline()
    for s in input:
        if s not in (server_socket, sys.stdin):
            s.send(data)
else:
    ...