TCP Console

tcp-console is a simple TCP-based interface designed for applications that need an external control channel. It provides a way to send commands to a running application to alter its behavior or fetch operational data. This project addresses these requirements by supporting both strongly-typed commands (structured data) and plain text commands for flexibility.

The console server listens for TCP connections on localhost (127.0.0.1) and handles incoming data by parsing commands and processing them. A response is optionally sent back to the client based on the command type.

Features

• Command Injection: Allows external control of an application via TCP.
• Supports Typed and Text Commands: Accepts strongly-typed commands and plain text commands for quick use cases.
• Async Networking: Uses tokio for handling multiple simultaneous connections efficiently.
• Examples Provided: The examples directory contains a demonstration of both plain text and structured command handling. One of the command handlers is showcased to report data to the remote connection.

Configuration Example

The examples directory contains an example with the following configuration. You may change these options at your convenience.

use tcp_console as console;
use tcp_console::Subscription;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let port = 3838;

    let console = console::Builder::new()
        .port(port)
        .welcome("Welcome to TCP console!")
        .subscribe(Services::Logger, Logger)?
        .subscribe(Services::Exec, Exec)?
        .subscribe(
            Services::Status,
            Status {
                connections: 11,
                health: "Operational".to_string(),
            },
        )?
        .accept_only_localhost()
        .build()?;

    console.spawn().await?;
    console.stop();

    Ok(())
}

In this example, Logger, Exec, and Status are types that implement the Subscription trait, allowing them to handle specific commands sent to the console.

Additionally, the example launches a separate task that sends three strongly-typed messages to the console. Two of these messages can be processed by existing subscribers, while the third will be reported as unprocessable.

To connect using a third-party client such as netcat, run the following command:
nc localhost 3838

Upon connection, the console will greet you with "Welcome to TCP console!". You can then send any text messages. However, the only text message recognized by Status (see impl Subscription for Status) is status. If this message is received, the status of a mock system will be reported back to netcat.