rgb-background.js

const express = require("express");
const execSync = require("child_process").execSync;
const fs = require("fs");
const app = express();
const port = 6969;

function padIP(ip) {
    let inflate = [];
    ip.split(":").forEach((x) => (x != "" ? inflate.push("0".repeat(4 - x.length) + x) : inflate.push("")));
    let zeroes = 0;
    inflate.forEach((x) => (zeroes += x.length));
    let final = "";
    inflate.forEach((x) => (x == "" ? (final += "0".repeat(32 - zeroes)) : (final += x)));

    return final.match(/.{1,4}/g).join(":");
}

app.get("/", (req, res) => {
    let userIP = padIP(req.connection.remoteAddress);

    // let connections = fs.readFileSync("/proc/net/sockstat6", {encoding:'utf8', flag:'r'}).split("\n");
    let connections = execSync("conntrack -L").toString().split("\n");

    connections = connections.map((l) => l.split(/\s+/g));
    connections = connections.filter((conn) => {
        if (conn[4] == undefined) {
            return false;
        }
        if (conn[4].includes(".")) {
            return false;
        }
        return padIP(conn[4].split("src=")[1] || "0:0:0:0:0:0:0:0") == userIP && conn[6] == `sport=${req.connection._peername.port}`;
    });

    let color;

    if (connections.length > 0) {
        color =
            "#" +
            padIP(connections[0][5].split("dst=")[1])
                .split(":")
                .slice(-3)
                .map((i) => i.slice(-2))
                .join("");
    } else {
        res.send("An error has occured, I am very sorry\n");
        return;
    }

    res.send(`Setting to color ${color}\n`);

    fs.writeFileSync("/var/www/rgb-background/currentColour.txt", color);
});

app.listen(port, () => {
    console.log(`Example app listening at http://localhost:${port}`);
});