client.py

import multiprocessing
import socket
import threading
import re

class Client(multiprocessing.Process):

    registered_server = None
    host = socket.gethostname()
    client_address = socket.gethostbyname(host)

    def __init__(self):
        self.run()

    def run(self):
        print("Client: Up and running")
        action = input("Client: Enter type of action ('r' to register): ")
        if (action == "r"):
            group = input("Client: Which group dou you want to join? ")
            self.register("register", group)

            send_thread = threading.Thread(target=self.send_message)
            receive_thread = threading.Thread(target=self.receive_messages)
            receive_new_server_thread = threading.Thread(target=self.receive_new_server)

            send_thread.start()
            receive_thread.start()
            receive_new_server_thread.start()

            # waiting for thread to stop = prevent the programm from shutdown before thread is stopped
            send_thread.join()
            receive_thread.join()

        else: 
            message = input("Client: Enter message:")
            print(message)

    def register(self, message_type, message_group):
        PORT = 49153

        MSG = bytes(message_type + '_' + message_group, 'utf-8')

        broadcast_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        broadcast_socket.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

        broadcast_socket.sendto(MSG, ('<broadcast>', PORT))
        
        data, server = broadcast_socket.recvfrom(1024)
        
        print('Client: Received message from server: ', data.decode('utf-8'))

        # search for server ip_address in message from server
        ip_pattern = r'\b(?:\d{1,3}\.){3}\d{1,3}\b'
        matches = re.findall(ip_pattern, data.decode('utf-8'))

        # 2nd ip address in message from server is server address
        self.registered_server_address = matches[1]
        
        #self.registered_server = server
        print("Client: My server: ", self.registered_server_address)

        broadcast_socket.close()

    def send_message(self):
        PORT = 50001

        while True:
            message = input()
            if message.lower() == 'exit':
                break
            
            client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            client_socket.connect((self.registered_server_address, PORT))
            client_socket.sendall(bytes(message, 'utf-8'))
            client_socket.close() 

    def receive_messages(self):
        PORT = 51000

        client_receive_message_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        client_receive_message_socket.bind((self.client_address, PORT))
        client_receive_message_socket.listen()

        print("Client: Listening for groupchat messages")

        while True:
            connection, addr = client_receive_message_socket.accept()
            message = connection.recv(1024)
            #print(f"GC message: {message.decode('utf-8')}")
            print(message.decode('utf-8'))

    def receive_new_server(self):
        PORT = 52000

        client_receive_message_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        client_receive_message_socket.bind((self.client_address, PORT))
        client_receive_message_socket.listen()

        print("Client: Listening for server address update messages")

        while True:
            connection, addr = client_receive_message_socket.accept()
            message = connection.recv(1024)
            print(f"Client: New server: {message.decode('utf-8')}")
            self.registered_server_address = message.decode('utf-8')