Ggtcf

I'm trying to understand networking on python using the socket module, but I think the problem is that I don't really understand how a server or client actually functions.

What I am trying to do:

• Send a dictionary from the client to the server by turning it to a string first using JSON


• Make the server send back a message to the client to confirm they are connected

Server program

import socket
import json

HOST = '192.168.X.X'
PORT = 50034


with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
 s.bind((HOST, PORT))
 s.listen(1)
 conn, addr = s.accept()

 with conn:
 while True:
 data = conn.recv(1024)
 new_data = data.decode()
 new_data = json.loads(data)
 print(new_data["Name"],"has connected from",addr)
 message = ("Hello %s welcome to the chat server" % new_data["Name"]).encode()
 s.sendall(message)
 if not data:
 conn.sendall(data)

Client program

import socket
import json

HOST = '192.168.X.X'
PORT = 50034

my_dict = "Name":"Bob"
jsn = json.dumps(my_dict)
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
 s.connect((HOST,PORT))
 s.sendall((jsn).encode())
 data = s.recv(1024)
 print(data)

But I am getting the error:

OSError: [Errno 57] Socket is not connected

Why?

In your server code, you need to change ...

s.sendall(message)

... to ...

conn.sendall(message)

This is because when you do ...

conn, addr = s.accept()

... conn is a new socket instance for that connection. So that's the object you should use for sending and receiving data on that connection. Before you call accept() to accept a connection, you don't have a socket that's actually connected to anything.