Unreliable Chat Client

Overview

This project implements an unreliable chat client that connects to a server of which the code is also created to send and receive messages. The client uses error-checking algorithms such as checksum and sequencing to ensure message integrity. It also supports various protocol commands to manipulate connections, including setting burst values, delay, and bit flips.

Features

• Checksum for Error Checking: Adds and verifies checksums to detect message corruption.
• Sequencing: Ensures that messages are received in the correct order.
• Protocol Commands: Supports commands for manipulating connections, including setting drop rate, flip rate, burst value, and delay.
• User Management: Allows users to log in with a unique username, checks for username availability, and lists online users.

Requirements

• Python 3.x
• socket library (standard library)
• threading library (standard library)
• math library (standard library)
• time library (standard library)
• re library (standard library)
• queue library (standard library)
• binascii library (standard library)

Usage

1. Running the Server:

   • Adjust the IP Address and port to your needs.
   • Ensure the port is free in order to run the server.

2. Running the Client:

   • Ensure the server is running and accessible.
   • Ensure the client uses the correct server address and port.
   • Run the client script: python3 chat_client.py.

3. Logging In:

   • Enter a unique username when prompted.
   • If the username is in use or contains disallowed characters, you will be prompted to enter a different username.

4. Sending Messages:

   • To send a message to a user: @username message
   • To see who is online: !who (Currently the implementation for adjusting the server values to manually create network circumstances is not finished yet)
   • To reset the server values: !reset
   • To get the value of a setting: !get SETTING_NAME
   • To set the value of a setting: !set SETTING_NAME value

5. Quitting:

   • To quit the client: !quit

Error Handling

• Checksum Errors: If a message fails checksum verification, an error message is sent back to the sender.
• Unknown Commands: If an unknown command is received, an appropriate error message is displayed.

Commands

• !quit: Quit the chat client.
• !who: List all online users.
• !reset: Reset server settings.
• !get [SETTING]: Get the value of a server setting.
• !set [SETTING] [VALUE]: Set the value of a server setting. Valid settings include DROP, FLIP, BURST, DELAY, BURST-LEN, and DELAY-LEN.

Protocol

• HELLO-FROM username: Login request.
• HELLO username: Login acknowledgment.
• IN-USE: Username already in use.
• BUSY: Server is full.
• SEND username message: Send a message to a user.
• DELIVERY username message: Deliver a message to the client.
• ERROR: Indicate an error in message delivery.
• ACK: Acknowledge receipt of a message.
• LIST: Request list of online users.
• LIST-OK user1,user2,...: List of online users.
• SET parameter value: Set server parameter.
• SET-OK: Acknowledge setting change.
• GET parameter: Get server parameter value.
• VALUE parameter value: Return server parameter value.

Implementation Details

• Checksum: Calculated by dividing the message into 4 parts, summing the binary values, and flipping the bits of the result.
• Sequencing: Uses sequence numbers to ensure messages are processed in the correct order.
• Multithreading: Uses separate threads for sending and receiving messages to handle concurrency.
• Error Handling: Checks for message integrity using checksums and sequence numbers, and handles various protocol errors.

License

This project is licensed under the Apache 2.0 License.