feat: client-client communication (#1)

client_client.py

@@ -0,0 +1,157 @@
+"""
+Client - Client communication overview:
+    - Server provides clients with an IP:port list (all available clients).
+    - Each client starts a TCP listener that other clients may connect to (listener runs in a separate thread, though also outputs to console).
+    - When a client wants to message another client, a TCP connection is opened, data is sent and the connection is closed. 
+"""
+
+import socket
+import threading
+import sys
+from typing import Dict, List
+
+
+def tcp_listener(port: int):
+    s = socket.socket()
+    # host = socket.gethostname()
+    host = '0.0.0.0'
+    s.bind((host, port))
+    s.listen(5)
+    print('TCP listener started on port', port)
+
+    while True:
+        conn, address = s.accept()
+        data = conn.recv(1024)
+        if not data:
+            break
+        data = data.decode('utf8')
+        try:
+            data_split = data.split()
+            name = data_split[0]
+            message = " ".join(data_split[1:])
+            print(f'{name} says: {message}')
+        except IndexError:
+            print(f'{address} sends an empty message.')
+        conn.sendall(bytes('OK', encoding='utf8'))
+
+
+def do_list(clients: List):
+    print("Available clients:")
+
+    for client in clients:
+        print(f'address: {client["ip"]}:{client["port"]}, nickname: {client["name"]}')
+
+
+def do_connect(address: Dict, username: str) -> bool:
+    """
+    address = {
+        'ip': "IPv4_ADDR"
+        'port: 1234
+    }
+    """
+    msg = input('Please provide your message: ')
+    try:
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.connect((address['ip'], address['port']))
+
+        s.sendall(bytes(f'{username} {msg}', encoding='utf8'))
+        resp = s.recv(1024)
+
+        s.close()
+    except socket.error as e:
+        print('[ERR]', e)
+        return False
+
+    if resp.decode('utf8') == 'OK':
+        return True
+    else:
+        return False
+
+
+def handle_actions(clients: List, username: str):
+    actions = ['list', 'msg', 'exit',]
+
+    input_split = input().split()
+    action = input_split[0]
+
+    if action not in actions:
+        print('[ERR] Incorrect command')
+        return
+
+    if action == 'list':
+        do_list(clients)
+
+    if action == 'msg':
+        try:
+            client_address = input_split[1]
+            client = {}
+            # check if client_address is an IP:port string or client name
+            cli_filtered = list(filter(lambda c: c['name'] == client_address, clients))
+
+            if len(cli_filtered): # client name found -> assign client
+                client = cli_filtered[0]
+            else:
+                # split input to separate IP / port
+                client['ip'] = client_address.split(':')[0]
+                client['port'] = int(client_address.split(':')[1])
+
+            success = do_connect(client, username)
+            if success:
+                print(f'Message to {client_address} delievered.')
+            else:
+                print(f'Error sending data to {client_address}')
+        except (IndexError, ValueError):
+            print('[ERR] incorrect address / name')
+            return
+
+    if action == 'exit':
+        print('Exiting...')
+        sys.exit(1)
+
+
+# this should be replaced with a dynamic list provided by the server
+client_list = [
+    {
+        'ip': '127.0.0.1',
+        'port': 1234,
+        'name': 'client1',
+    },
+    {
+        'ip': '127.0.0.1',
+        'port': 6969,
+        'name': 'client2',
+    },
+    {
+        'ip': '127.0.0.1',
+        'port': 8888,
+        'name': 'client3',
+    },
+]
+
+usage_str = """
+Commands:
+    list - display available clients
+    msg CLIENT_NAME/CLIENT_ADDRESS - connect to one of the clients specified in <list>
+    wait - allow other clients to connect to you 
+    exit - close chat client
+"""
+
+if __name__ == '__main__':
+    listener_port = 5000
+
+    while True:
+        try:
+            listener_port = int(input('TCP Listener port number (must be an integer): '))
+            break
+        except ValueError:
+            print('[ERR] Incorrect port number.')
+
+    username = input('Your Username: ')
+
+    threading.Thread(target=tcp_listener, args=(listener_port,)).start()
+
+
+    print(usage_str)
+
+    while True:
+        handle_actions(client_list, username)