Python socket problem-ConnectionRefusedError: [WinError 10061]

Question

I wanted to create a server-client chatbox room in python, where multiple clients could send messages in the chat box.

This is the server code

import threading
import socket

#setting up the local host and the local port
host = '127.0.0.1'
port = 9879

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((host, port)) #hosting the server to the host
server.listen() #server listen to incoming connection

#list for client and their nicknames
clients = []
nicknames = []

#broadcast method to send message to all the clients connected to the server
def broadcast(message):
    for client in clients:
        client.send(message)

def handle (client):
    while True:
        try:
            message = client.recv(1024)
            broadcast(message)
        except: #if the connection is lost, discard the client
            index = clients.index(client)
            clients.remove(client)
            client.close()
            nickname = nicknames[index]
            broadcast(f'{nickname} already left the chat!'.encode('ascii'))
            nicknames.remove(nickname)
            break

#function to receive connection
def receive():
    while True:
        client, address = server.accept()
        print(f"Conncected with {str(address)}")
        client.send('NICKNAME'.encode('ascii'))
        nickname = client.recv(1024).decode('ascii')
        nicknames.append(nickname)
        clients.append(client)
        
        print(f'The nickname of the client is {nickname}')
        broadcast(f'{nickname} joined the chat!'.encode('ascii'))
        client.send('Connected to the server!'.encode('ascii'))
        
        #making thread for every client
        thread = threading.Thread(target = handle, args = (client,))
        thread.start()
print("Server is waiting for client...")

and this is the client code

import socket
import threading 

#nickname prompt
nickname = input("Input your nickname: ")
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#binding the client to the port
client.connect(('127.0.0.1', 9879))

def receive():
    while True:
        try:
            message = client.recv(1024).decode('ascii')
            if message == 'NICKNAME':
                client.send(nickname.encode('ascii'))
            else:
                print(message)
        except:
            print("An error occurred!")
            client.close()
            break

def write():
    while True:
        message = f'{nickname}: {input("")}'
        client.send(message.encode('ascii'))

#making the thread
receive_thread = threading.Thread(target = receive)
receive_thread.start()

write_thread = threading.Thread(target = write)
write_thread.start()

However, whenever i inputted the nickname in the command prompt there was an error

Traceback (most recent call last):
  File "C:\Users\march\Documents\Programming\Pyhton\client.py", line 8, in <module>
    client.connect(('127.0.0.1', 9879))
ConnectionRefusedError: [WinError 10061] No connection could be made because the target machine actively refused it

I wonder what's the problem because the port for both server and client are the same and the port is available.

Answer 1

On your server code you're missing a call to the receive function that runs the while loop and puts the server on accept for connections.

The code becomes

import threading
import socket

#setting up the local host and the local port
host = '127.0.0.1'
port = 9879

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((host, port)) #hosting the server to the host
server.listen() #server listen to incoming connection

#list for client and their nicknames
clients = []
nicknames = []

#broadcast method to send message to all the clients connected to the server
def broadcast(message):
    for client in clients:
        client.send(message)

def handle (client):
    while True:
        try:
            message = client.recv(1024)
            broadcast(message)
        except: #if the connection is lost, discard the client
            index = clients.index(client)
            clients.remove(client)
            client.close()
            nickname = nicknames[index]
            broadcast(f'{nickname} already left the chat!'.encode('ascii'))
            nicknames.remove(nickname)
            break

#function to receive connection
def receive():
    while True:
        client, address = server.accept()
        print(f"Conncected with {str(address)}")
        client.send('NICKNAME'.encode('ascii'))
        nickname = client.recv(1024).decode('ascii')
        nicknames.append(nickname)
        clients.append(client)
        
        print(f'The nickname of the client is {nickname}')
        broadcast(f'{nickname} joined the chat!'.encode('ascii'))
        client.send('Connected to the server!'.encode('ascii'))
        
        #making thread for every client
        thread = threading.Thread(target = handle, args = (client,))
        thread.start()
print("Server is waiting for client...")

receive() # runs the function that accepts for incoming connections

---

The client code should run the write() function on the main thread and not on another one, because it requires input from the stdin. You can change your code as follows in order to run the receiving routine on another thread and your "writing" function on the main one.

import socket
import threading 

#nickname prompt
nickname = input("Input your nickname: ")
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#binding the client to the port
client.connect(('127.0.0.1', 9879))

def receive():
    while True:
        try:
            message = client.recv(1024).decode('ascii')
            if message == 'NICKNAME':
                client.send(nickname.encode('ascii'))
            else:
                print(message)
        except:
            print("An error occurred!")
            client.close()
            break

def write():
    while True:
        message = f'{nickname}: {input("")}'
        client.send(message.encode('ascii'))

#making the thread
receive_thread = threading.Thread(target = receive)
receive_thread.start()

# on the main thread
write()

The cause of the Connection refused error was due to the fact that the server code immediately exited since the receive function was never actually called.