TCP/IP Sockets - modified

The following pair of scripts is a modified version of a previous post which shows how to set up a TCP connection in Python. The scripts are to be run in two terminal windows on the same machine.

Run the server script and the server will start waiting for client connection using port 5000. Then, you can start a client script in another terminal window to connnect to the server. Once the client connects to the server, you can send the following messages to the server on the client side:

1. h - get the help menu from the server.
2. c - close the client connection without closing the server.
3. x - close both the client and the server.
4. Ctrl-C - quit the client abnormally.
5. other - send text to the server and get an echo.

Source Code

---

Server Side

# TCP server example
import socket, time

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind(("", 5000))
server_socket.listen(1) # listen to at most 1 client
server_socket.settimeout(5) # timeout for server socket = 5 sec.

mEndServer = False
while not mEndServer:
    print "Waiting for call..."
    try:
        client_socket, address = server_socket.accept()
    except socket.timeout:
        if mEndServer:
            break
        continue
    print "I got a connection from ", address
    
    # handle a client connection
    while True:
        mdata = client_socket.recv(512)
        if mdata=='':
            # client is quit abnormally
            print 'Client is quit.'
            break            
        elif mdata=='c':
            # close client without
            # ending server
            print "Client is closed\n"
            break
        elif mdata=='x':
            # ending server
            print "Server is closed\n"
            mEndServer = True
            break
        elif mdata=='h':
            # help
            print 'Client calls for help'
            mMsg = '\nc - close client connection\n'
            mMsg += 'h - print help message\n'
            mMsg += 'x - turn off server\n'
            client_socket.send(mMsg)
        elif mdata!='':
            print "RECEIVED from client:" , mdata
            mMsg = "Your data is %s\n" % mdata
            client_socket.send(mMsg)
    client_socket.close()
server_socket.close()

Client Side

# TCP client example
import socket

client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect(("localhost", 5000))

while True:
    data = raw_input("Message sent to server:")
    client_socket.send(data)
    if data == 'x':
        # tell server to close
        break
    if data == 'c':
        # close client only
        break
    if data == '':
        # close client only
        break
    print "Waiting for server to feed back..."
    data = client_socket.recv(512)
    print "RECEIVED from server:" , data

client_socket.close()

If you want to connect to the server with a different machine on the network, you should change localhost in the client script to the IP of the server (say 192.168.0.80).

Output

---

Server Side

Waiting for call...
I got a connection from  ('127.0.0.1', 48448)
RECEIVED from client: hello
RECEIVED from client: how are you?
RECEIVED from client: can you see me?
Client calls for help
Client is closed

Waiting for call...
I got a connection from  ('127.0.0.1', 48450)
Server is closed

Client Side

Message sent to server:hello
Waiting for server to feed back...
RECEIVED from server: Your data is hello

Message sent to server:how are you?
Waiting for server to feed back...
RECEIVED from server: Your data is how are you?

Message sent to server:can you see me?
Waiting for server to feed back...
RECEIVED from server: Your data is can you see me?

Message sent to server:h
Waiting for server to feed back...
RECEIVED from server: 
c - close client connection
h - print help message
x - turn off server

Message sent to server:c 

# python c.py
Message sent to server:x