Detect (non-blocking) key press while accepting client connections - python-3.x

Question

I am fairly new at programming in python. I am trying to code some form of simulation using sockets. I am able connect multiple clients to the server successfully. However I would like the server to accept client connections while waiting for some input (say enter key or a string input from the console/terminal). If the user presses the enter key or enters that string, then the server should stop accepting client connections and send the list of connected clients to all clients. I know how to code the rest of the part but I dont know where to detect this key press while accepting connections. This is what I have so far. I have tried looking for similar approaches taken, but I have not found something that fits my needs.
Server File:
import socket, sys, traceback, json, pygame, curses, time
from threading import Thread
clientList = {}
def initialize():
serverConnect()
def serverConnect():
local_hostname = socket.gethostname()
host = socket.gethostbyname(local_hostname)
port = 6666
sockfd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sockfd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
try:
sockfd.bind((host, port))
except:
print("Bind failed. Error : " + str(sys.exc_info()))
sys.exit()
sockfd.listen(3)
cid = 0
# infinite loop - do not reset for every requests
while True:
print("Awaiting client connection...")
clientSocket, address = sockfd.accept()
cid += 1
add_client_to_list(cid, address)
ip = str(address[0])
port = str(address[1])
print("Connected with " + ip + ":" + port)
try:
Thread(target=client_thread, args=(clientSocket, ip, port, cid, address)).start()
except:
print("Thread did not start.")
traceback.print_exc()
sockfd.close()
def client_thread(clientSocket, ip, port, cid, address, BUFSIZE = 5120):
clientAddress = address
clientID = cid
print("Sending client ID " + str(clientID) + " to " + ip + ":" + port)
clientSocket.sendall(str(clientID).encode("utf-8"))
threadActive = True
while threadActive:
recdData = receive_input(clientSocket, BUFSIZE)
if "--QUIT--" in recdData:
print("Client is requesting to quit")
clientSocket.close()
print("Connection " + ip + ":" + port + " closed")
threadActive = False
else:
print("\nReceived: {}".format(recdData) + " from %d" %clientID)
clientSocket.sendall("-".encode("utf8"))
def receive_input(clientSocket, BUFSIZE):
recdData = clientSocket.recv(BUFSIZE)
recdDataSize = sys.getsizeof(recdData)
if recdDataSize > BUFSIZE:
print("The input size is greater than expected {}".format(recdDataSize))
decodedData = recdData.decode("utf8").rstrip() # decode and strip end of line
result = process_input(decodedData)
return result
def process_input(input_str):
return str(input_str).upper()
def add_client_to_list(client_ID, client_address):
clientList[client_ID] = client_address
print(clientList)
def send_client_list(clientSocket, clientList):
jsonList = json.dumps(clientList)
clientSocket.sendall(str(jsonList).encode("utf-8"))
def keyPress(stdscr):
"""checking for keypress"""
stdscr.nodelay(True) # do not wait for input when calling getch
return stdscr.getch()
if __name__ == "__main__":
initialize()
Client File:
import socket
import sys
import json
def initialize():
sockfd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = socket.gethostname()
port = 6666
try:
sockfd.connect((host, port))
except:
print("Connection error")
sys.exit()
# Receiving server assigned client ID
try:
myID = sockfd.recv(1024).decode("utf-8")
print("Received ID: " + myID + " from server.")
except:
print("Could not receive my ID from server")
sys.exit()
print("Enter 'quit' to exit and 'list' to receive client List")
message = input(" -> ")
while True:
if message == "list":
print("Receiving clientList from server...")
try:
jsonList = sockfd.recv(8192).decode("utf-8")
clientList = json.loads(jsonList)
print("Received list: %s" % clientList)
except:
print("Could not receive list from server")
sys.exit()
elif message != 'quit':
sockfd.sendall(message.encode("utf8"))
if sockfd.recv(5120).decode("utf8") == "-":
pass
message = input(" -> ")
else:
sockfd.send(b'--quit--')
break;
if __name__ == "__main__":
initialize()
This is what I have found. It is a small script which detects if the user inputs {a} on the console. And if he does, then a message is printed. Else it keeps listening for key presses.
import curses, time
def keyPress(stdscr):
# checking for keypress
stdscr.nodelay(True) # do not wait for input when calling getch
return stdscr.getch()
while True:
if curses.wrapper(keyPress) == 97:
print("You pressed 'a'")
else:
pass
time.sleep(0.1)
It would be great if you could guide me how I can use this concept to detect key press on the server side and stop accepting client connections and call the function to send client list to all clients. Or if you have any other approaches or suggestions.