m3u8.js

// ==UserScript==
// @name        Intercept m3u8 streams
// @description Intercept XHR/fetch requests involving m3u8 stream identifiers
// @namespace   Violentmonkey Scripts
// @match       *://*/*
// @version     0.1
// @author      Noah Betzen
// @grant       none
// ==/UserScript==

const STORAGE_KEY = `seenm3u8streams`;

(function() {
    `use strict`;

    const seenString = localStorage.getItem(STORAGE_KEY);
    const seen = seenString ? JSON.parse(seenString) : {};
    const count = Object.keys(seen).length;

    if (count > 0) {
        console.log(`Seen m3u8 streams: ${count}`, seen);
    }

    const originalFetch = fetch;
    const originalXMLHttpRequest = window.XMLHttpRequest;

    window.fetch = async function(...args) {
        const response = await originalFetch.apply(this, args);

        if (JSON.stringify(args).includes(`m3u8`)) {
            // This is async but we don`t await it on purpose so that the response returns quickly
            processFetch(response.clone(), seen);
        }

        return response;
    };

    window.XMLHttpRequest = function(...args) {
        const xhr = new originalXMLHttpRequest(...args);

        xhr.addEventListener(`readystatechange`, function() {
            if (xhr.readyState === 4 && xhr.status === 200) {
                const lines = xhr.responseText.split(`\n`);
                lines.forEach((line, index) => {
                    if (line.includes(`m3u8`)) {
                        processXHR(line, seen);
                    }
                });
            }
        });

        return xhr;
    };
})();


async function processFetch(resp, seen) {
    const responseData = await resp.json();

    console.log(`Fetch m3u8 discovered`, responseData)

    // TODO: Finish fetch implementation (only need XHR currently)
    return responseData;
}

async function processXHR(line, seen) {
    // Key url is stripped of query/hash params
    const url = new URL(line);
    const keyUrl = url.origin + url.pathname;

    if (!seen[keyUrl]) {
        console.log(`Unseen URL: ${keyUrl}`)

        // TODO: No easy way to download the thing, use CLI tool on collected URLs

        seen[keyUrl] = line;
        localStorage.setItem(STORAGE_KEY, JSON.stringify(seen));
    }
}