systemquery/src/lib/transport/Connection.mjs

"use strict";

import net from 'net';
import { EventEmitter, once } from 'events';

import l from 'log';
import nexline from 'nexline';

import settings from '../../settings.mjs';
import rekey from './rekey.mjs';
import { write_safe } from '../io/StreamHelpers.mjs';
import { encrypt_bytes, decrypt_bytes } from '../crypto/secretbox.mjs';

/**
 * Represents a connection to a single endpoint.
 */
class Connection extends EventEmitter {
	constructor(secret_join) {
		super();
		
		this.session_key = Buffer.from(secret_join, "base64");
	}
	
	/**
	 * Connects to a peer and initialises a secure TCP connection thereto.
	 * @param	{string}		address	The address to connect to.
	 * @param	{string}		port	The TCP port to connect to.
	 * @return	{net.Socket}	A socket setup for secure communication.
	 */
	async connect(address, port) {
		this.address = address; this.port = port;
		this.socket = new new.Socket();
		this.socket.connect({
			address, port
		});
		await once(this.socket, "connect");
		this.socket.setKeepAlive(true);
		
		this.session_key = await rekey(this.socket, this.session_key);
		
		this.reader = nexline({
			input: this.socket
		});
		
		this.read_task = read_loop();
	}
	
	destroy() {
		this.socket.destroy();
		this.emit("destroy");
	}
	
	async read_loop() {
		try {
			for await (let line of this.reader)  {
				handle_message(line);
			}
		}
		catch(error) {
			l.warn(`Warning: Killing connection to ${this.address}:${this.port} after error: ${settings.cli.verbose ? error : error.message}`);
		}
		finally {
			this.destroy();
		}
	}
	
	handle_message(text) {
		let message = JSON.parse(text);
		
	}
	
	async send(message) {
		// TODO: Implement a binary frame-based protocol here instead? It would be 33% more bandwidth efficient.
		// Perhaps <length> <data>? If messages are too long, we'll have to do something about that though....
		let payload = JSON.stringify(message);
		payload = encrypt_bytes(this.session_key, payload);
		
		await write_safe(this.socket, payload);
	}
}

export default Connection;