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Commit df8e811

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Create Chat Room With Python Socket
Create Chat Room With Python Socket
1 parent eac29b8 commit df8e811

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2 files changed

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2 files changed

+224
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lines changed

‎client.py‎

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import sys
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import socket
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import select
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import errno
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HEADER_LENGTH = 10
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IP = "192.168.204.1"
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PORT = 5052
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my_username = input("Username: ")
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# Create a socket
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# socket.AF_INET - address family, IPv4, some otehr possible are AF_INET6, AF_BLUETOOTH, AF_UNIX
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# socket.SOCK_STREAM - TCP, conection-based, socket.SOCK_DGRAM - UDP, connectionless, datagrams, socket.SOCK_RAW - raw IP packets
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client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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# Connect to a given ip and port
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client_socket.connect((IP, PORT))
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# Set connection to non-blocking state, so .recv() call won;t block, just return some exception we'll handle
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client_socket.setblocking(False)
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# Prepare username and header and send them
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# We need to encode username to bytes, then count number of bytes and prepare header of fixed size, that we encode to bytes as well
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username = my_username.encode('utf-8')
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username_header = f"{len(username):<{HEADER_LENGTH}}".encode('utf-8')
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client_socket.send(username_header + username)
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while True:
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# Wait for user to input a message
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message = input(f'{my_username} > ')
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# If message is not empty - send it
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if message:
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# Encode message to bytes, prepare header and convert to bytes, like for username above, then send
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message = message.encode('utf-8')
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message_header = f"{len(message):<{HEADER_LENGTH}}".encode('utf-8')
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client_socket.send(message_header + message)
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try:
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# Now we want to loop over received messages (there might be more than one) and print them
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while True:
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# Receive our "header" containing username length, it's size is defined and constant
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username_header = client_socket.recv(HEADER_LENGTH)
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# If we received no data, server gracefully closed a connection, for example using socket.close() or socket.shutdown(socket.SHUT_RDWR)
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if not len(username_header):
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print('Connection closed by the server')
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sys.exit()
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# Convert header to int value
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username_length = int(username_header.decode('utf-8').strip())
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# Receive and decode username
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username = client_socket.recv(username_length).decode('utf-8')
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# Now do the same for message (as we received username, we received whole message, there's no need to check if it has any length)
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message_header = client_socket.recv(HEADER_LENGTH)
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message_length = int(message_header.decode('utf-8').strip())
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message = client_socket.recv(message_length).decode('utf-8')
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# Print message
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print(f'{username} > {message}')
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except IOError as e:
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# This is normal on non blocking connections - when there are no incoming data error is going to be raised
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# Some operating systems will indicate that using AGAIN, and some using WOULDBLOCK error code
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# We are going to check for both - if one of them - that's expected, means no incoming data, continue as normal
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# If we got different error code - something happened
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if e.errno != errno.EAGAIN and e.errno != errno.EWOULDBLOCK:
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print('Reading error: {}'.format(str(e)))
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sys.exit()
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# We just did not receive anything
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continue
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except Exception as e:
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# Any other exception - something happened, exit
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print('Reading error: '.format(str(e)))
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sys.exit()

‎server.py‎

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import socket
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import select
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HEADER_LENGTH = 10
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IP = "192.168.204.1"
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PORT = 5052
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# Create a socket
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# socket.AF_INET - address family, IPv4, some otehr possible are AF_INET6, AF_BLUETOOTH, AF_UNIX
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# socket.SOCK_STREAM - TCP, conection-based, socket.SOCK_DGRAM - UDP, connectionless, datagrams, socket.SOCK_RAW - raw IP packets
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server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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# SO_ - socket option
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# SOL_ - socket option level
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# Sets REUSEADDR (as a socket option) to 1 on socket
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server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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# Bind, so server informs operating system that it's going to use given IP and port
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# For a server using 0.0.0.0 means to listen on all available interfaces, useful to connect locally to 127.0.0.1 and remotely to LAN interface IP
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server_socket.bind((IP, PORT))
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# This makes server listen to new connections
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server_socket.listen()
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# List of sockets for select.select()
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sockets_list = [server_socket]
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# List of connected clients - socket as a key, user header and name as data
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clients = {}
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print(f'Listening for connections on {IP}:{PORT}...')
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# Handles message receiving
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def receive_message(client_socket):
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try:
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# Receive our "header" containing message length, it's size is defined and constant
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message_header = client_socket.recv(HEADER_LENGTH)
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# If we received no data, client gracefully closed a connection, for example using socket.close() or socket.shutdown(socket.SHUT_RDWR)
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if not len(message_header):
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return False
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# Convert header to int value
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message_length = int(message_header.decode('utf-8').strip())
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# Return an object of message header and message data
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return {'header': message_header, 'data': client_socket.recv(message_length)}
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except:
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# If we are here, client closed connection violently, for example by pressing ctrl+c on his script
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# or just lost his connection
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# socket.close() also invokes socket.shutdown(socket.SHUT_RDWR) what sends information about closing the socket (shutdown read/write)
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# and that's also a cause when we receive an empty message
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return False
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while True:
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# Calls Unix select() system call or Windows select() WinSock call with three parameters:
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# - rlist - sockets to be monitored for incoming data
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# - wlist - sockets for data to be send to (checks if for example buffers are not full and socket is ready to send some data)
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# - xlist - sockets to be monitored for exceptions (we want to monitor all sockets for errors, so we can use rlist)
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# Returns lists:
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# - reading - sockets we received some data on (that way we don't have to check sockets manually)
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# - writing - sockets ready for data to be send thru them
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# - errors - sockets with some exceptions
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# This is a blocking call, code execution will "wait" here and "get" notified in case any action should be taken
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read_sockets, _, exception_sockets = select.select(sockets_list, [], sockets_list)
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# Iterate over notified sockets
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for notified_socket in read_sockets:
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# If notified socket is a server socket - new connection, accept it
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if notified_socket == server_socket:
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# Accept new connection
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# That gives us new socket - client socket, connected to this given client only, it's unique for that client
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# The other returned object is ip/port set
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client_socket, client_address = server_socket.accept()
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# Client should send his name right away, receive it
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user = receive_message(client_socket)
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# If False - client disconnected before he sent his name
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if user is False:
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continue
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# Add accepted socket to select.select() list
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sockets_list.append(client_socket)
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# Also save username and username header
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clients[client_socket] = user
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print('Accepted new connection from {}:{}, username: {}'.format(*client_address, user['data'].decode('utf-8')))
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# Else existing socket is sending a message
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else:
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# Receive message
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message = receive_message(notified_socket)
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# If False, client disconnected, cleanup
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if message is False:
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print('Closed connection from: {}'.format(clients[notified_socket]['data'].decode('utf-8')))
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# Remove from list for socket.socket()
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sockets_list.remove(notified_socket)
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# Remove from our list of users
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del clients[notified_socket]
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continue
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# Get user by notified socket, so we will know who sent the message
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user = clients[notified_socket]
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print(f'Received message from {user["data"].decode("utf-8")}: {message["data"].decode("utf-8")}')
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# Iterate over connected clients and broadcast message
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for client_socket in clients:
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# But don't sent it to sender
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if client_socket != notified_socket:
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# Send user and message (both with their headers)
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# We are reusing here message header sent by sender, and saved username header send by user when he connected
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client_socket.send(user['header'] + user['data'] + message['header'] + message['data'])
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# It's not really necessary to have this, but will handle some socket exceptions just in case
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for notified_socket in exception_sockets:
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# Remove from list for socket.socket()
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sockets_list.remove(notified_socket)
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# Remove from our list of users
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del clients[notified_socket]

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