server.py

# network imports
import socket
# system imports
import threading
# protocol imports
import json
from pprint import pprint

# socket imports
from network import read, write



# constant variables
CMD_EXIT = "exit"
CMD_SYSINFO = "sysinfo"
CMD_CLOSE = "close"



# Server is for creating a listener which can accept clients.
class Server:
    # constructor
    def __init__(self, address):
        # opening a socket
        self.__sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        # for keeping the connections
        self.__sockets = []

        self.__start(address)

    # start method will bind and start our server
    def __start(self, address): 
        self.__sock.bind(address)
        self.__sock.listen(0)

        print(f"Server start listening on {address[0]}:{address[1]} ...")
    
    # handle method handles clients
    def handle(self):
        while True:
            connection, address = self.__sock.accept()

            print(f"=> {address[0]} connected on port {address[1]}")

            self.__sockets.append(connection)
    
    # get info reads user data from sockets
    def __get_info(self, index):
        sock = self.__sockets[index]
        write(sock, CMD_SYSINFO.encode('utf-8'))
        info = json.loads(read(sock).decode('utf-8'))
        pprint(info)
    
    # close socket closes a client connection
    def __close_socket(self, index):
        sock = self.__sockets.pop(index)

        write(sock, CMD_CLOSE.encode('utf-8'))

        sock.close()

        print('Closed:')
        print(sock)
        print()
    
    # print sockets generates sockets information for user
    def __print_sockets(self):
        sockets = [f"{s.getpeername()[0]}:{s.getpeername()[1]}" for s in self.__sockets]
        if len(sockets) < 1:
            print('Empty')

            return
        
        print()
        print("Enter [sysinfo/close] [index] to get peer system information or close connection:")
        for i, p in enumerate(sockets):
            print(f"\t[{i + 1}] {p}")
        
        print()
    
    # process the commands to server
    def process(self, command, index):
        if command == CMD_SYSINFO:
            self.__get_info(index)
        elif command == CMD_CLOSE:
            self.__close_socket(index)
        else:
            self.__print_sockets()
    
    # close server method shutdowns the server socket
    def close_server(self):
        [s.close() for s in self.__sockets]

        self.__sock.close()

        exit(0)



# start server
if __name__ == "__main__":
    # creating a server instance
    server = Server(("0.0.0.0", 5000))

    # start accepting clients
    conn_thread = threading.Thread(target=server.handle, daemon=True)
    conn_thread.start()
    
    # getting inputs
    while True:
        command = input().split()

        if command[0] == CMD_EXIT:  # with exit command, terminate
            server.close_server()

            exit(0)

        if len(command) < 2:
            command.append(0)

        server.process(command[0], int(command[1])-1)