Python socket throwing the following error ConnectionResetError: [Errno 54] Connection reset by peer

I have been trying to create a messaging service in python using sockets. I have written the code to host two connections and allow one to send messages to the other using username and host_addr.

But every time I try to connect the second client and send a message from the first getting the following error.

ConnectionResetError: [Errno 54] Connection reset by peer

Server.py

import socket
import _thread as thread
HOST = "127.0.0.1" # Standard loopback interface address (localhost)
PORT = 1237 # Port to listen on (non-privileged ports are > 1023)
user_mapping = {}
def on_new_client(conn, addr): data = conn.recv(1024) data = data.decode() print(data) print(user_mapping) if data[:8] == "username": user_mapping[data[9:]] = (addr, data[9:]) elif data[0] == "@": for i in user_mapping.values(): if i[0] == addr: from_user = i[1] else: str = "user not found" conn.sendto(str.encode(), addr) str = "%s:%s" % (from_user, data[data.find(":") + 1:]) conn.sendto(str.encode(), user_mapping[data[1:data.find(":")](0)]) else: pass
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(10)
while True: conn, addr = s.accept() thread.start_new_thread(on_new_client,(conn,addr))
s.close()

Client.py

import socket
HOST = "127.0.0.1" # The server's hostname or IP address
PORT = 1237 # The port used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
username = input("Enter user name")
str = "username: %s" % username
s.send(str.encode())
while True: message = input(username+">") s.send(message.encode()) data = s.recv(1024) print(data)

Was hoping some would could answer why this is happening and guide me to any good links where there is Information on creating a messaging service in python.

1 Answer

Client is sending 2 messages and then receiving one. But server just listen once and then send one or two packages.

Chronologically:

1. Client sends a package, and server reads it.
2. Then both client and server try to send a package. Both packages that won't meet a listening peer.
3. Then client try to receive a package, but server won't send (he already sent it before) or it may send but its too late because communication is already broken.

Concepts you may implement always:

1. If one talk, another one may listen.
2. If a package is mean to be sent, it shall be sent anyway. Dont let a 'if' statment that send package when at 'else' that does not (or viceversa).

==== EDIT ====

About solution:

You need to work with paralel loops. Take a look at this code

He uses two threads on client, one for keep listening for new server updates (messages for other people) and another one to wait input from user.