Huy Nguyen - Toan Ly - Toan Nham

Proj2-Networks-CS4065

This is a project 2 for Computer Networks class - Fall 2024

Project Overview: This project implements a Bulletin Board System using a client-server architecture with sockets. It supports:

• A single public message board where users can join, post, and retrieve messages.
• Multiple private message groups where users can join specific groups, post, and interact with users within those groups.
• Both the client and server are written in Python.

Compilation and Running Instructions

Prerequisites: Ensure Python (version 3.6 or later) is installed.

Steps to Run

1. Start the Server:

   • Navigate to the directory containing the server.py file.
   • Run "python server.py" in the terminal

2. Start the client:

   • Navigate to the directory containing client.py file.
   • Run "python client.py" in the different terminal

Usability Instructions

Part 1:

• %connect localhost 8080: Connect to the server.
• %join: Join the public message board.
• %post : Post a message to the public message board.
• %users: Retrieve a list of users in the public message board.
• %message <message_id>: Retrieve the content of a specific message by ID.
• %leave: Leave the public message board.
• %exit: Disconnect from the server and exit the client.

Part 2:

• %groups: Retrieve a list of all available groups.
• %groupjoin <group_name>: Join a specific group or multiple groups (separated by a comma). E.g: %groupjoin g1,g2,g3
• %grouppost <group_name> : Post a message to a private group's message board.
• %groupusers <group_name>: Retrieve a list of users in the specified group.
• %groupleave <group_name>: Leave a specific group.
• %groupmessage <group_name> <message_id>: Retrieve the content of a specific message in a private group.

Issues Encountered and Solutions

1. Bug: Users from one group could retrieve messages from other groups (#21)

   • Problem: A user in one group was able to access messages posted in other groups. -> Solution: Updated the message retrieval logic to filter messages based on the user’s current group(s). Make sure that group-specific message boards were accessed only by authorized users.

2. Bug: Users from one group could post messages to another group

   • Problem: Users were inadvertently able to post messages to groups they were not a part of. -> Solution: Added a validation layer in the server to check a user’s group membership before allowing message posts. Unauthorized attempts are rejected, and the user is notified that they're not members of that specific group.

3. Bug: Users in one group could view members of other groups

   • Problem: Users were able to see the usernames of members in groups they were not part of. -> Solution: Enhanced the %groupusers functionality to restrict the visibility of users to only those in the requesting user’s groups. Added a check for group membership during user list retrieval.

4. Bug: After a user left a group, other members couldn’t continue sending messages

   • Problem: Leaving a group disrupted the server's ability to manage messages for the group. -> Solution: Fixed the group leave functionality to properly update group membership records. Make sure that group message boards remained active for remaining members and broadcasted a notification about the user’s exit to all other group members.