Python, How to Send data over TCP

Question

I need to create a simple server that listens for TCP connections. If it receives text on<EOF> or off<EOF> then it sends (echo) back success. The receiving part is working, but now i need it to send back success.

Code:

# import threading
import SocketServer

class TCPHandler(SocketServer.BaseRequestHandler): 

   def handle(self):
      self.msg = self.request.recv(1024).strip()
      if self.msg == "on<EOF>":
         print "Turning On..."
         #ECHO "SUCCESS<EOF>"        <----- I need the server to echo back "success"
      if self.msg == "off<EOF>":
         print "Turning Off..."
         #ECHO "SUCCESS<EOF>"        <----- I need the server to echo back "success"


      if __name__ == "__main__": 
         host, port = '192.168.1.100', 1100

  # Create server, bind to local host and port 
  server = SocketServer.TCPServer((host,port),TCPHandler)

  print "server is starting on ", host, port

  # start server
  server.serve_forever()

Answer 1

If you need an endless/ continuous server connection you can use the following server code.

Server Code

    import socket  # Import socket module
    
    port = 50000  # Reserve a port for your service every new transfer wants a new port or you must wait.
    s = socket.socket()  # Create a socket object
    host = ""  # Get local machine name
    s.bind(('localhost', port))  # Bind to the port
    s.listen(5)  # Now wait for client connection.
    
    print('Server listening....')
    
    x = 0
    
    while True:
        conn, address = s.accept()  # Establish connection with client.
    
        while True:
            try:
                print('Got connection from', address)
                data = conn.recv(1024)
                print('Server received', data)
    
                st = 'Thank you for connecting'
                byt = st.encode()
                conn.send(byt)
    
                x += 1
    
            except Exception as e:
                print(e)
                break
    
    conn.close()

Client Code

    import socket  # Import socket module
    import os
    import re
    
   
    s = socket.socket()  # Create a socket object
    port = 50000  # Reserve a port for your service every new transfer wants a new port or you must wait.
    
    s.connect(('localhost', port))
    x = 0
    
    st = str(x)
    byt = st.encode()
    s.send(byt)
    
   # send message for hundred times
    while x<100:
        st = str(x)
        byt = st.encode()
        s.send(byt)
    
        print(x)
    
        while True:
            data = s.recv(1024)
            if data:
                print(data)
                x += 1
                break
    
            else:
                print('no data received')
    
    
    
    print('closing')
    s.close()
    
    

Answer 2

A better approach from the python 3 docs would be:

Server

import socketserver

class MyTCPHandler(socketserver.BaseRequestHandler):
    """
    The request handler 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()

Client

import socket
import sys

HOST, PORT = "localhost", 9999
data = " ".join(sys.argv[1:])

# Create a socket (SOCK_STREAM means a TCP socket)
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    # Connect to server and send data
    sock.connect((HOST, PORT))
    sock.sendall(bytes(data + "\n", "utf-8"))

    # Receive data from the server and shut down
    received = str(sock.recv(1024), "utf-8")

print("Sent:     {}".format(data))
print("Received: {}".format(received))

Hope it helps. Arturo

Answer 3

Well i did it a day before following a very good tutorial, cant find the link but here is the code

client.py

import socket

host = socket.gethostname()
port = 12345                   # The same port as used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
s.sendall(b'Hello, world')
data = s.recv(1024)
s.close()
print('Received', repr(data))

For server

echo_server.py

import socket

host = ''        # Symbolic name meaning all available interfaces
port = 12345     # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))

print host , port
s.listen(1)
conn, addr = s.accept()
print('Connected by', addr)
while True:

    try:
        data = conn.recv(1024)

        if not data: break

        print "Client Says: "+data
        conn.sendall("Server Says:hi")

    except socket.error:
        print "Error Occured."
        break

conn.close()