ShellWe

Shell We chat? Using this application, a user can chat with other users in the chat room.

Building the Application

To build the ChatClient or ChatServer application, you can use the provided CMakeLists.txt file. The following steps will guide you through building the application.

Prerequisites

• cmake
• make
• gcc
• ncurses
• clang-tidy
• libcriterion-dev
• pthread
• git

Steps

git clone https://github.com/olincollege/ShellWe.git
cd ShellWe
mkdir build && cd build
cmake ..
make
# To test the server and utility functions
cd test
./test_server
./test_util

# To run the server locally
cd ../src/server
./ChatServer

# To run the client locally
cd ../client
./ChatClient 0.0.0.0

Context

Our chat application provides an interface for users to chat with each other using TCP/IP socket connections to the server. This program is an extremely simplified version of Internet Relay Chat (IRC) where we only have a single combined chat and service server. While a normal user will not be interacting with the server directly, a server administrator will be accessing ShellWe through remote ssh connection to the cloud hosting service, Google Cloud Platform, or the provided console.

Containers

The chat system consists of two main parts: a server application and a client application, both written in C. The server will interact with all the connected clients and the clients will be able to communicate with each other through the relaying chat server.

Components

Server Application

The server application is hosted on a virtual machine available on Google Cloud Compute Engine service. Network and firewall settings were configured such that the virtual machine's ip address was accessible publicly for the TCP/IP connections from chat application. We acknowledge that this is not the safest choice, but for the sake of demonstration, we chose to go with the naive configuration.

For the server container, we have two main components that run asynchronously.

• Main Server Thread: This component continuously listens for incoming TCP connections on a predefined port. Once a connection is established, it spawns a new thread (Worker Thread) to handle the connection.
• Worker Thread: Each connection has a dedicated worker thread. This thread is responsible for reading messages from the client, processing them if needed. It will relay the message to all the other connected clients.

To ensure proper management of connected clients, we used a mutex to protect an array that contains all the connected socket file descriptor numbers.

Client Application

To provide an enhanced user experience, we used ncurses library for our text user interface. Once a user enters required information for configuration, an input and output handlers are created and handles all network I/O tasks with the server connected through TCP/IP socket.