This is a small project that utilizes CSharp and the .NET library (7.0). This program allows you to establish multiple web sockets at once (client -> server and server -> client both supported). This is intended to run on Linux-based operating systems that support .NET 7.0 (e.g. using the dotnet package). It is possible this works with Windows, but I haven't tried testing it. This project should also work with .NET 8.0, but I haven't tested that as well.

This program operates as a very simple one-on-one chat room. When connected, the client and server can exchange basic UTF-8 text messages with each other.

I made this project to learn more about web sockets in CSharp/.NET along with how to manage multiple web sockets receiving/sending data concurrently via asynchronous methods.

Demo

Here's a GIF video demonstrating the functionality of the program. We don't use SSL in our demonstration and establish the client and server both locally using 127.0.0.1 (localhost).

Building & Installing

Prerequisites

.NET 7.0

The .NET 7.0 library is required to run this project. You can install this library manually or through a package manager if your Linux distro supports it.

On Ubuntu/Debian-based systems, you may install Dotnet using the below command(s).

# Typically this is only required for Debian.
wget https://packages.microsoft.com/config/debian/12/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb
sudo apt update

# Install .NET 7.0.
sudo apt install -y dotnet-sdk-7.0

Building & Running

If you want to build and run the project. You can use the following command.

dotnet run

If you want to only build the project, you can use the following command.

dotnet build

Make sure you're in the same directory as the csharp-websockets.csproj file when performing the above commands.

Command Line

The following command line arguments are supported.

• -z --cfg => The path to the config file. By default, it looks for ./conf.json.
• --nolisten => Prevents the listen server from activating.
• --host => Overrides the host address to listen on.
• --port => Overrides the port to listen on.
• --ssl => Overrides the listen SSL option.
• -l --list => Lists all values of config and exits.

Configuration

A config file on the file system is read and parsed via the JSON syntax. The default path it checks for is ./conf.json. However, it can be changed via the config path command line option listed above.

Here are the config options. Please keep in mind you will need to remove the comments (//) if copying below. I recommend taking a look at the conf.ex.json file if you want to copy the configuration without any errors.

{
    // Whether to activate the listen server.
    "listen": true,

    // The host to listen on.
    "listenHost": "127.0.0.1",

    // The port to listen on.
    "listenPort": 2222,

    // Whether to listen with SSL.
    "listenSsl": false,

    // An array of startup client connections.
    "startupConnections": [
        {
            // The startup connection host.
            "host": "127.0.0.1",
            
            // The startup connection port.
            "port": 2223,

            // Whether to use SSL with the startup connection.
            "ssl": false
        }
    ]
}

Usage

When starting up the program, you will be prompted with the following commands you can use.

• ls - List all server connections. The number at the beginning represents the index which should be used with other commands.
• lc - List all client connections. The number at the beginning represents the index which should be used with other commands.
• new <ip> <port> <ssl> - Establish a new client connection to <ip>:<port>. <ssl> is optional and to disable SSL, use no.
• cc <idx> - Send/receive messages for client connection at index <idx>.
• cs <idx> - Send/receive messages for listen server at index <idx>.
• rc <idx> - Remove client at index <idx>.
• rs <idx> - Remove server at index <idx>.
• h - Print top/help menu.
• q - Exit program.

When connected to a chat session via the cc and cs commands, you can send the message \q to detach the current chat session and return to the main menu.

Notes

• This project is still a work in progress. I have not yet tested SSL.
• Only one connection to the listen server is supported at the moment. New connections will override the previous connection. However, I may add support for multiple connections in the future when I have more time.
• There are some code that can definitely be improved on/organized better.

Credits

• Christian Deacon