Multithreaded Python TCP Robot Server 🤖

Repository Overview 📄

This repository contains a multithreaded TCP server implementation designed to control remote robots, allowing them to authenticate, navigate to a target coordinate, and retrieve a secret message. The project is implemented in Python and adheres to the specifications provided by the university Computer Networks course.

Repository Structure 📂

• main.py: The main server program implementing the multithreaded TCP server.
• README.md: This README file providing an overview and usage instructions.
• tester-arm: The tester executable for ARM architecture to validate the server implementation against predefined tests.

Course Description and Task Overview 📚

The Computer Networks course includes practical and theoretical tasks focusing on network communication protocols. The specific task is to create a multithreaded server for TCP/IP communication that can handle multiple clients (robots) simultaneously. Each robot starts at a random coordinate and must navigate to the origin [0,0] to pick up a secret message.

Detailed Specification 🔍

Communication Protocol 🔐

Communication between the server and robots is conducted via a pure textual protocol with commands ending in a special sequence "\a\b".

Server Messages 📩

• SERVER_MOVE: Command to move one position forward.
• SERVER_TURN_LEFT: Command to turn left.
• SERVER_TURN_RIGHT: Command to turn right.
• SERVER_PICK_UP: Command to pick up the message.
• SERVER_LOGOUT: Command to terminate the connection after a successful message discovery.
• SERVER_KEY_REQUEST: Command to request Key ID for authentication.
• SERVER_OK: Positive acknowledgment.
• SERVER_LOGIN_FAILED: Authentication failed.
• SERVER_SYNTAX_ERROR: Incorrect message syntax.
• SERVER_LOGIC_ERROR: Message sent in an incorrect situation.
• SERVER_KEY_OUT_OF_RANGE_ERROR: Key ID out of the expected range.

Client Messages 📨

• CLIENT_USERNAME: Message with the username.
• CLIENT_KEY_ID: Message with the Key ID.
• CLIENT_CONFIRMATION: Message with the confirmation code.
• CLIENT_OK: Confirmation of performed movement, including robot coordinates.
• CLIENT_RECHARGING: Robot starts recharging.
• CLIENT_FULL_POWER: Robot has recharged and resumes operations.
• CLIENT_MESSAGE: Text of the discovered secret message.

Authentication Process 🔒

1. Client sends username.
2. Server requests Key ID.
3. Client sends Key ID.
4. Server sends a confirmation code calculated using the username and server key.
5. Client sends its confirmation code.
6. Server verifies the confirmation code and responds with SERVER_OK or SERVER_LOGIN_FAILED.

Robot Navigation 📡

The server guides the robot to the origin [0,0] using a series of SERVER_MOVE, SERVER_TURN_LEFT, and SERVER_TURN_RIGHT commands. The robot responds with its current coordinates after each move.

Secret Message Discovery 🎁

Once at [0,0], the server sends SERVER_PICK_UP to retrieve the secret message from the robot. The server then sends SERVER_LOGOUT to terminate the connection.

Recharging Process 🔋

Robots notify the server when they start recharging (CLIENT_RECHARGING) and resume operations with CLIENT_FULL_POWER.

Special Situations and Error Handling ⛔️

• Timeouts: Connections are terminated if messages are not received within specified intervals.
• Syntax Errors: The server responds with SERVER_SYNTAX_ERROR for incorrect message formats.
• Logic Errors: Errors during the recharging process result in SERVER_LOGIC_ERROR.

Technologies and Concepts Used 🛠️

• Python:
  • Multithreading with the Thread class from the threading module.
  • Socket programming using the socket module.
  • Exception handling for robust error detection and response.
• TCP/IP Communication:
  • Implementing a custom communication protocol over TCP.
  • Managing concurrent client connections using threads.

Launching the Server and Client 🚀

Running the Server

1. Ensure Python is installed on your system.
2. Navigate to the project directory.
3. Run the server using the following command:

python3 main.py

Running the Tester

1. Ensure the tester executable is available in the project directory.
2. Launch the tester in a compatible environment (e.g., VirtualBox with Tiny Core Linux).
3. Run the tester with the appropriate parameters:

   tester <port number> <server address> [test number(s)]

   • Example:

     tester 4321 127.0.0.1 2 3 8 | less

Conclusion 📝

This repository provides a comprehensive implementation of a multithreaded TCP server for robot control, following the detailed specifications provided by the Computer Networks course. The project demonstrates practical applications of network programming, multithreading, and custom protocol implementation in Python.