discordapp_url_bruteforce.js

/**
 * @param {String} HTML representing a single element
 * @return {Element}
 */
function htmlToElement(html) {
    var template = document.createElement('template');
    html = html.trim();
    template.innerHTML = html;
    return template.content.firstChild;
}

/**
 * @param {String} full url to the image
 * @param {String} proxy
 * @param {Number} timeout Network timeout in ms
 * @return {String} | false
 */
async function tryURL(url, proxy, timeout) {
    try {
        const controller = new AbortController();
        const timeoutId = setTimeout(() => controller.abort(), timeout);
        const response = await fetch(proxy + url, {
            signal: controller.signal
        });
        
        if (!response.ok) {
            return false;
        }
        
        if (response.status >= 400) {
            return false;
        }
        
        return url;
    } catch (error) {
        return false;
    }
}

/**
 * DOM elements must be ready before calling this function
 * @param {BigInt} a
 * @param {BigInt} b
 * @param {Number} timeout Network timeout in ms
 */
async function processPair(a, b, proxy, timeout) {
    const images = document.querySelector('#images');
    const counter = document.querySelector('#counter-ok');
    const counterFail = document.querySelector('#counter-fail');
    const lastA = document.querySelector('#last-a');
    const lastB = document.querySelector('#last-b');

    const url = `https://cdn.discordapp.com/attachments/${a}/${b}/unknown.png`;
    let response = await tryURL(url, proxy, timeout);

    if (response) {
        let value = BigInt(counter.dataset.value) + BigInt('1');
        counter.innerHTML = value;
        counter.setAttribute('data-value', value);
        images.appendChild(htmlToElement(`<img src="${response}" />`));
    } else {
        let value = BigInt(counterFail.dataset.value) + BigInt('1');
        counterFail.innerHTML = value;
        counterFail.setAttribute('data-value', value);
    }
    
    lastA.innerHTML = a;
    lastB.innerHTML = b;
}

function prepareDomNodes() {
    document.body.innerHTML = '';
    document.body.className = '';
    document.body.appendChild(htmlToElement(`
        <style>
            html, body { color: hsl(1, 0%, 15%); background: hsl(1, 0%, 90%); }
            #counter { font-weight: bold; }
            #counter-ok { color: hsl(115, 65%, 45%); }
            #counter-fail { color: hsl(1, 65%, 45%); }
            img { max-width: 100vmax; max-height: 100vmax; }
        </style>
    `));
    document.body.appendChild(htmlToElement(`
        <div id="box">
            <section id="counter">
                <div id="last-values">
                    <p>a: <span id="last-a"></span></p>
                    <p>b: <span id="last-b"></span></p>
                </div>
                <div id="counter-ok" data-value="0">...</div>
                <div id="counter-fail" data-value="0">...</div>
            </section>
            <div id="images"></div>
        </div>
    `));
}

/**
 * @param {BigInt} a
 * @param {BigInt} aMax
 * @param {BigInt} b
 * @param {BigInt} bMax
 * @param {String} proxy CORS proxy url
 * @param {Number} timeout Network timeout in ms
 */
async function processAll(a, aMax, b, bMax, proxy, timeout) {
    for (let newA = a; newA <= aMax; newA = newA + 1n) {
        for (let newB = b; newB <= bMax; newB = newB + 1n) {
            await processPair(newA, newB, proxy, timeout);
        }
    }
}

/**
 * And freeze your browser!
 * last a/b will be out of order too
 *
 * @param {BigInt} a
 * @param {BigInt} aMax
 * @param {BigInt} b
 * @param {BigInt} bMax
 * @param {String} proxy CORS proxy url
 * @param {Number} timeout Network timeout in ms
 */
function processAllAtIncredibleHihgSpeed(a, aMax, b, bMax, proxy, timeout) {
    for (let newA = a; newA <= aMax; newA = newA + 1n) {
        for (let newB = b; newB <= bMax; newB = newB + 1n) {
            processPair(newA, newB, proxy, timeout);
        }
    }
}

/** main entry **/
const proxy = "https://cors.bridged.cc/";
const timeout = 3000; // how long to wait for each request (in ms)

// "a" and "b" are part of the URL
// https://cdn.discordapp.com/attachments/494986892228689931/889331310705909760/unknown.png

const a = BigInt("494986892228689931");
const b = BigInt("889331310705909760");

// how far go from a and b
const aMax = a + 100n;
const bMax = b + 100n;

const gottaGoFast = false; // set to true if you hate your computer

/** main entry end **/

prepareDomNodes();

if (gottaGoFast) {
    processAllAtIncredibleHihgSpeed(a, aMax, b, bMax, proxy, timeout);
} else {
    processAll(a, aMax, b, bMax, proxy, timeout);
}