How to close a socket connection in python?

Question

I have socket server and socket client two side programs:

The server:

#!/usr/bin/env python3
#-*- coding:utf-8 -*-
# Author:sele


import socket

HOST = '127.0.0.1'
PORT = 65432

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((HOST, PORT))
    s.listen()
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)

        if addr and addr[0] != '127.0.0.44':
            conn.sendall(b'ip error')  # there I want to cut off the socket connection.

        else:

            while True:
                data = conn.recv(1024)
                if not data:
                    break

                conn.sendall(data)

the client:

#!/usr/bin/env python3
#-*- coding:utf-8 -*-
# Author:lele

import socket

HOST = '127.0.0.1'
PORT = 65432

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.connect((HOST, PORT))
    s.sendall(b'Hello, world')
    data = s.recv(1024)

print('Received', repr(data))

you see, in my server code: if addr and addr[0] != '127.0.0.44': there I want to close the connection, how to do with it?

whether just add the conn.close() code in that place?

because I tried use conn.close(), then the server seems stop running now:

sele-MacBook-Pro:test01 ldl$ ./tests02-server.py 
Connected by ('127.0.0.1', 53321)
sele-MacBook-Pro:test01 ldl$

Jeremy Friesner · Accepted Answer · 2019-04-13 04:36:44Z

5

Calling conn.close() is indeed the correct way to close the connection.

because I tried use conn.close(), then the server seems stop running now:

Right, because that's what you programmed the server to do. In particular, the client closing the connection causes conn.recv(1024) to return None, which causes your if-test to succeed and then break breaks the server out of its while-loop, and from there the server exits, because there are no further loops for it to execute.

        while True:
            data = conn.recv(1024)
            if not data:
                break

If you want the server to keep running (and accept another socket connection) afterwards, you need to put another while True: loop around the code that starts at the s.accept() line, i.e.:

while True:
   conn, addr = s.accept()
   with conn:
       print('Connected by', addr)
       [...]

edited Apr 13, 2019 at 4:36

answered Apr 13, 2019 at 4:20

Jeremy Friesner

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