Python Chat Application (Client & Server)

A simple TCP chat application in Python using socket and threading, supporting multiple clients, message broadcasting, and automatic reconnection.

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Features

• Multi-client support: Multiple users can connect to the server simultaneously.
• Broadcasting: Messages are sent to all connected clients except the sender.
• Username handshake: Clients provide a username upon connecting.
• Connection management: Detects client disconnections and cleans up.
• Automatic client reconnection: Clients keep trying to reconnect if the server is unavailable.
• Error handling: Graceful handling of exceptions and lost connections.

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Server (server_socket.py)

How it works

1. Socket setup: Creates a TCP socket bound to HOST and PORT.
2. Accepting connections: Continuously accepts new clients and asks for their username.
3. Message handling: Each client runs in a separate thread. Messages are received and broadcast to other clients.
4. Disconnection handling: If a client disconnects or an error occurs, it removes the client and informs others.

Usage

python server_socket.py

You will see output like:

✅ Server running on 127.0.0.1:8081
[+] Alice connected from ('127.0.0.1', 12345)
[MSG] Alice: Hello everyone
[-] Alice disconnected

Client (client_socket.py)

How it works

1. Username prompt: Asks the user for a username at the start.
2. Connection loop: Tries to connect to the server. If unavailable, retries every 5 seconds.
3. Message receiving: Continuously listens for messages from the server. Automatically handles server disconnections.
4. Message sending: User inputs messages, which are sent to the server and broadcast to others.

Usage

python client_socket.py

You will see output like:

Enter your username: Alice
✔ Connected to server
Bob: Hello!
Alice: Hi Bob!

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Key Funtions

Server

• broadcast(messge, _client): Sends a message to all clients except _client.
• handle_messages(client): Receives messages from a client, detects disconnections, and broadcast messages.
• receive_connections(): Continuosly accepts new client connections and stars a handler thread for each.

Client

• connect_to_server(): Tries to connect to the server with retries.
• receive_message(): Continuosly listen for server messages. Handles server disconnections.
• write_messages(): Sends user input to the server if connected.

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Notes

• All messages are encoded/decoded in UTF-8 for network transmission.
• Disconnections are handled gracefully both on the server and client sides.
• Threads are used to allow simultaneous sending and receiving of messages.